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Transcriber's note:
    This book was published in two volumes, of which this is the first.
    The second volume was released as Project Gutenberg ebook #45395,
    available at http:www.gutenberg.org/ebooks/45395. Italic text has
    been marked with _underscores_. Please see the end of this Project
    for further notes.




  [Illustration]

    Sir Thos. Lawrence pinxt.          W. H. Worthington sculpt.

    H. Davy

    Engraved by permission of the Council of
    the Royal Society from the original painting.

    London, Published by Henry Colburn & Richard Bentley 1831.




    THE LIFE
    OF
    SIR HUMPHRY DAVY,
    BART. LL.D.

    LATE PRESIDENT OF THE ROYAL SOCIETY, FOREIGN ASSOCIATE
    OF THE ROYAL INSTITUTE OF FRANCE,
    &c. &c. &c.

    BY
    JOHN AYRTON PARIS, M.D. CANTAB. F.R.S. &C.

    FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS.

    IN TWO VOLUMES.

    VOL. I.

    LONDON:
    HENRY COLBURN AND RICHARD BENTLEY,
    NEW BURLINGTON STREET.
    MDCCCXXXI.




    LONDON:
    PRINTED BY SAMUEL BENTLEY,
    Dorset-street, Fleet-street.




    TO
    HIS ROYAL HIGHNESS
    PRINCE AUGUSTUS FREDERICK,
    DUKE OF SUSSEX, K.G. D.C.L.
    _&c. &c. &c._
    PRESIDENT OF THE ROYAL SOCIETY;

    THESE MEMOIRS OF A PHILOSOPHER
    WHOSE SPLENDID DISCOVERIES
    ILLUMINED THE AGE IN WHICH HE LIVED,
    ADORNED THE COUNTRY WHICH GAVE HIM BIRTH,
    AND OBTAINED FROM FOREIGN AND HOSTILE NATIONS
    THE HOMAGE OF ADMIRATION AND
    THE MEED OF GRATITUDE,
    ARE,
    BY THE GRACIOUS PERMISSION OF HIS ROYAL HIGHNESS,
    DEDICATED WITH SENTIMENTS OF PROFOUND RESPECT,

    BY

    THE AUTHOR.




PREFACE.


The reflecting portion of mankind has ever felt desirous of
becoming acquainted with the origin, progress, habits, and
peculiarities of those whom the powers of genius may have raised
above the plane of intellectual equality; but neither the nature of
the information, nor the extent of the detail that may be necessary
to satisfy so laudable a curiosity, can ever be estimated by any
common standard, since it is not in our nature to contemplate an
object of admiration, but with reference to our own predilections
and sympathies; and hence every reader will form a scale for
himself, according to the degree of interest he may feel for the
particular character under review. The Poetical enthusiast, who
could not sufficiently express his gratitude on being told that
Milton wore shoe-buckles, would very probably not have given
'four farthings,' as Gray says, to know that the shoes of Davy
were tanned by catechu; and yet if the relative value of this
information were fairly estimated, it must be admitted that the
former is a matter of barren curiosity, the latter, a fact of some
practical utility. In a word, we very naturally connect the man
with his works, and we care not to extend our acquaintance with the
one, but in proportion as we have derived pleasure from the other.

In like manner, very different estimates will be formed of the
degree of praise due to a distinguished philosopher, because the
few who are deeply imbued with a knowledge of the science he may
have adorned and enlightened must not only appreciate the value
of his labours, but understand the difficulties which opposed
the accomplishment of them, before they can arrive at a sound
decision upon the question: and here again the judgment of the
most scientific may be unfortunately warped; it may be corrupted
by secret passions or sinister influences; be distorted by the
prejudices of education and habit, or unduly biassed by invincible
prepossessions.

No man ever soared, like an eagle, to the pinnacle of fame,
without exciting the envy and perhaps the hatred of those who
could only crawl up half-way; while, on the other hand, where
no rivalry can exist, the splendour of such an ascent will
captivate the bystander, and by exciting intemperate triumph and
unqualified admiration, change without diminishing the sources of
erroneous judgment, and substitute adulation for calumny. Under
such circumstances, an allusion even to the common frailties of
genius becomes offensive; the biographer is called upon for the
delineation of a perfect man; but the world is satisfied with
nothing short of 'a faultless monster;' and yet, while they would
impose upon him the same restraint as Queen Elizabeth laid upon
her artist--to execute a portrait without a single shadow, they
little imagine how completely they obscure the features of their
idol, by the haze of incense in which they continually envelope
it. These are evils against which a future historian will not have
to contend; for time tries the characters of men, as the furnace
assays the quality of metals, by disengaging the impurities,
dissipating the superficial irridescence, and leaving the sterling
gold bright and pure.

Nor can the extent of our obligations to a philosopher be
appreciated until time shall have shown the various important
purposes to which his discoveries may administer. The names of
Mayow and Hales might have been lost in the stream of discovery,
had not the results of Priestley and Lavoisier shown the value
and importance of their statical experiments on the chemical
relations of air to other substances. The discoveries of Dr. Black
on the subject of _latent_ heat could never have obtained that
celebrity they now enjoy, had not Mr. Watt availed himself of their
application for the improvement of the steam-engine; and the views
of Sir H. Davy respecting the true nature of chlorine become daily
more important from the discovery of new elements of an analogous
nature. In future ages, the metals of the alkalies and earths may
admit of applications, and open new avenues of knowledge, of which
at present we can form no idea; but it is obvious that, in the
page of history, his name will gather fame in proportion as such
discoveries unfold themselves.

It must be admitted, that such considerations may furnish
an argument against the propriety of writing the life of a
contemporaneous philosopher; and yet I will never admit, with Mr.
Babbage, that "the volume of his biography should be sealed, until
the warm feelings of surviving kindred and admiring friends shall
be cold as the grave, from which remembrance vainly recalls his
cherished form, invested with all the life and energy of recent
existence."

Is it not possible that the errors of partiality, which have
so frequently been charged upon the writer on these occasions,
may often be ascribed, with greater truth and justice, to the
prejudices of the reader--that, after all, the distortion might
not have existed in the portrait itself, but in the optics of the
observer? Such an opinion, however, even were it true, carries
along with it no consolation to the biographer; for I know of no
method by which the picture can be adapted to the focus of every
eye.

If, however, contemporaneous biography has its difficulties and
impediments, so has it also its advantages. Dr. Johnson has
remarked, in his Life of Addison, that "History may be formed from
permanent monuments and records; but Lives can only be written
from personal knowledge, which is growing every day less, and in a
short time is lost for ever. The delicate features of the mind, the
nice discriminations of character, and the minute peculiarities of
conduct, are soon obliterated."

I did not enter upon this arduous and delicate task, without
a distinct conception of the various difficulties which would
necessarily oppose its accomplishment. I well knew that
the biographer of Davy must hold himself prepared for the
dissatisfaction of one party at the commendations he might bestow,
and for the displeasure of the other at the penury of his praise,
or the asperity of his criticism.

After great labour and much anxiety, I have at length completed the
work; and in giving it to the world, I shall apply to myself the
words of Swift--"I have the ambition to wish, at least, that both
parties may think me in the right; but if that is not to be hoped
for, my next wish should be, that both might think me in the wrong,
which I would understand as an ample justification of myself, and
a sure ground to believe that I have proceeded, at least, with
impartiality, and perhaps even with truth."

It is certainly due to myself, and perhaps to the world, to
state the circumstances by which I was induced to undertake a
work requiring for its completion a freedom from anxiety, and an
extent of research, scarcely compatible with the occupations of
a laborious profession; and which, I may add, has been wholly
composed during night, in hours stolen from sleep. Very shortly
after the death of Sir Humphry Davy, an account of his life,
written by no friendly hand, nor 'honest chronicler,' was submitted
for my judgment by a Journalist who had intended to insert it in
his paper. At my request, it was committed to the flames; but
not until I had promised to supply the loss by another memoir.
The sketches by which I redeemed this pledge were published in a
weekly journal--THE SPECTATOR; and they have since been copied into
various other works, sometimes with, but frequently without any
acknowledgment. They constitute the greater part of the Life which
was printed in the Annual Obituary for 1829; and they form the
introduction to an edition of his "Last Days," lately published in
America.

I was soon recognised as the writer of these Sketches; and the
leading publishers of the day urged me to undertake a more extended
work. To these solicitations I returned a direct refusal: I even
declined entering upon any conversation on the occasion; feeling
that the wishes of Lady Davy, at that time on the Continent, ought
in the very first instance to be consulted on the subject. Had not
the common courtesy of society required such a mark of attention,
the wish expressed by Sir Humphry in his Will would have rendered
it an imperative duty. On her arrival in London, in consequence
of a letter she had addressed to Mr. Murray, I requested an
interview with her Ladyship, from whom I received not only an
unqualified permission to become the biographer of her illustrious
husband, but also the several documents which are published with
acknowledgement in these memoirs. I still felt that Dr. Davy might
desire to accomplish the task of recording the scientific services
of his distinguished brother; and, had that been the case, I should
most undoubtedly have retired without the least hesitation or
reluctance; but I was assured by those who were best calculated to
form an opinion upon this point,--for he was himself absent from
England,--that motives of delicacy which it was easy to appreciate,
would at once lead him to decline an undertaking embarrassed with
so many personal considerations. The task, however, of collating
the various works of Sir H. Davy, and of enriching them by notes
derived from his own knowledge of the circumstances under which
they were written, I do hope will be accomplished by one who is so
well calculated to heighten the interest, and to increase the value
of labours of such infinite importance to science, and to the best
interests of mankind.

The engraving which adorns the volume is from a painting by Sir
Thomas Lawrence, presented to the Royal Society by Lady Davy; and
I beg the Council of that learned body to accept my thanks for the
permission they so readily granted for its being engraved. It is
one of the happiest efforts of the distinguished Artist, and is
the only portrait I have seen in which his features are happily
animated with the expression of the poet, and whose eye is bent to
pursue the flights of his imagination through unexplored regions.

I must also embrace this opportunity of publicly expressing my
thanks to the Managers of the Royal Institution, who, in the most
handsome manner, immediately complied with my request to inspect
their Journals, and to make such extracts from them, as I might
consider necessary for the completion of my memoirs.

To Mr. Davies Gilbert, I am under obligations which it is difficult
for me to acknowledge in adequate terms, not only for the value of
the materials with which he has furnished me, but for the kindness
and urbanity with which they were communicated, and for the ready
and powerful assistance which I have so constantly received from
him during the progress of the work.

To the other enlightened individuals from whom I have received
support, I have acknowledged my obligations in the body of the
work; and should I have inadvertently passed over any service
without a becoming notice, I trust the extent of the labour and
the circumstances under which it has been performed, will plead my
apology.

    Dover Street, January 1, 1831.




CONTENTS.


    CHAPTER I.

    Birth and family of Sir H. Davy.--Davy placed at a preparatory
    school.--His peculiarities when a boy.--Anecdotes.--He is admitted
    into the grammar-school at Penzance.--Finishes his education
    under Dr. Cardew at Truro.--Death of his father.--He is apprenticed
    by his mother to Mr. John Bingham Borlase, a surgeon
    and apothecary.--He enters upon the study of Chemistry, and devotes
    more time to Philosophy than to Physic.--The influence of
    early impressions illustrated.--His poetical talent.--Specimens of
    his versification.--An Epic Poem composed by him at the age of
    twelve years.--His first original experiment in chemistry.--He
    conceives a new theory of heat and light.--His ingenious experiment
    to demonstrate its truth.--He becomes known to Mr. Davies
    Gilbert, the founder of his future fortunes.--Mr. Gregory Watt
    arrives at Penzance, and lodges in the house of Mrs. Davy.--The
    visit of Dr. Beddoes and Professor Hailstone to Cornwall.--The
    correspondence between Dr. Beddoes and Mr. Davies Gilbert, relative
    to the Pneumatic Institution at Bristol, and the proposed appointment
    of Davy.--His final departure from his native town          Page 1

    CHAPTER II.

    Cursory thoughts on the advantages of Biography.--Plan and
    objects of the Pneumatic Institution.--Davy contracts friendships
    during his residence at Bristol.--His first visit to London.--His
    Letters to Mr. Davies Gilbert.--The publication of the West Country
    Contributions, by Dr. Beddoes.--Davy's Essays on Heat, Light,
    and Respiration.--His interesting experiments on bonnet canes.--He
    commences an enquiry into the nature of nitrous oxyd.--He
    publishes his chemical researches.--A critical examination of the
    work.--Testimony of Tobin, Clayfield, Southey, and others, respecting
    the powers of nitrous oxyd.--Davy breathes carburetted
    hydrogen gas, and nearly perishes from its effects.--His new Galvanic
    experiments communicated in a Letter to Mr. Gilbert             56

    CHAPTER III.

    Count Rumford negotiates with Mr. Underwood on the subject of Davy's
    appointment to the Royal Institution.--Terms of his engagement
    communicated in a letter to Mr. Gilbert.--Davy arrives, and takes
    possession of his apartments.--He receives various
    mortifications.--He is elected a member of the Tepidarian
    Society.--Is appointed Lecturer instead of assistant.--He makes a
    tour in Cornwall with Mr. Underwood.--Anecdotes.--His Poem on
    Spinosism.--His letter to Mr. Gilbert, communicating a galvanic
    discovery.--He commences his first grand course of lectures.--His
    brilliant success.--A letter from Mr. Purkis.--Davy's style
    criticised.--His extraordinary method of experimenting.--Davy and
    Wollaston compared as experimentalists.--The style of Davy as a
    lecturer and a writer contrasted                               114

    CHAPTER IV.

    Davy makes a tour with Mr. Purkis through Wales.--Beautiful
    phenomenon observed from the summit of Arran Benllyn.--Letter
    to Mr. Gilbert.--Journal of the Institution.--Davy's papers on
    Eudiometry, and other subjects.--His first communication to the
    Royal Society, on a new galvanic pile.--He is proposed as a Fellow,
    and elected into the Society.--His paper on astringent vegetable
    substances, and on their operation in tanning leather.--His
    letter to Mr. Poole.--He is appointed Chemical Lecturer to the
    Board of Agriculture.--He forms friendships with the Duke of
    Bedford, Mr. Coke, and many other celebrated agriculturists.--Attends
    the sheep-shearing at Holkham and Woburn.--Composes
    a Prologue to "The Honey-Moon"                                 150

    CHAPTER V.

    Sir Thomas Bernard allots Davy a piece of ground for Agricultural
    Experiments.--History of the Origin of the Royal Institution.--Its
    early labours.--Davy's Letters to Mr. Gilbert and to Mr.
    Poole.--Death of Mr. Gregory Watt.--Davy's Passion for Fishing,
    with Anecdotes.--He makes a Tour in Ireland: his Letters on
    the subject.--His Paper on the Analysis of the Wavellite.--His
    Memoirs on a new method of analysing Minerals which contain a
    fixed Alkali.--Reflections on the discovery of Galvanic
    Electricity                                                    188

    CHAPTER VI.

    The History of Galvanism divided into six grand Epochs.--Davy
    extends the experiment of Nicholson and Carlisle.--His Pile of one
    metal and two fluids.--Dr. Wollaston advocates the doctrine of
    oxidation being the primary cause of Voltaic Phenomena.--Davy's
    modification of that theory.--His Bakerian Lecture of 1806.--He
    discovers the sources of the acid and alkaline matter eliminated
    from water by Voltaic action.--On the nature of Electrical
    decomposition and transfer.--On the relations between the Electrical
    energies of bodies, and their Chemical affinities.--General
    developement of the Electro-chemical Laws.--Illustrations,
    Applications, and Conclusions                                  216

    CHAPTER VII.

    The unfair rivalry of Philosophers.--Bonaparte the Patron of
    Science--He liberates Dolomieu.--He founds a Prize for the
    encouragement of Electric researches.--His letter to the Minister of
    the Interior.--Proceedings of the Institute.--The Prize is conferred
    on Davy.--The Bakerian Lecture of 1807.--The Decomposition of
    the Fixed Alkalies--Potassium--Sodium.--The Questions to which
    the discovery gave rise.--Interesting Extracts from the Manuscript
    notes of the Laboratory.--Potash decomposed by a chemical
    process.--Letters to Children, and Pepys.--The true nature
    of Potash discovered.--Whether Ammonia contains oxygen.--Davy's
    severe Illness.--He recovers and resumes his labours.--His
    Fishing Costume.--He decomposes the Earths.--Important views
    to which the discovery has led                                 253

    CHAPTER VIII.

    Davy's Bakerian Lecture of 1808.--Results obtained from the
    mutual action of Potassium and Ammonia upon each other.--His
    belief that he had decomposed Nitrogen.--He discovers Telluretted
    Hydrogen.--Whether Sulphur, Phosphorus, and Carbon may not
    contain Hydrogen.--He decomposes Boracic acid.--Boron.--His
    fallacies with regard to the composition of Muriatic acid.--A
    splendid Voltaic battery is constructed at the Institution by
    subscription.--Davy ascertains the true nature of the Muriatic and
    Oxymuriatic Acids.--Important chemical analogies to which the
    discovery gave origin.--Euchlorine.--Chlorides.--He delivers
    Lectures before the Dublin Society.--He receives the Honorary Degree
    of LL.D. from the Provost and Fellows of Trinity College.--He
    undertakes to ventilate the House of Lords.--The Regent confers upon
    him the honour of Knighthood.--He delivers his farewell
    Lecture.--Engages in a Gunpowder manufactory.--His marriage    307

    CHAPTER IX.

    Davy's "Elements of Chemical Philosophy" examined.--His
    Memoir on some combinations of Phosphorus and Sulphur, &c.--He
    discovers Hydro-phosphoric gas.--Important Illustrations of
    the Theory of Definite Proportionals.--Bodies precipitated from
    water are Hydrats.--His letter to Sir Joseph Banks on a new
    detonating compound.--He is injured in the eye by its explosion.--His
    second letter on the subject.--His paper on the Substances
    produced in different Chemical processes on Fluor Spar.--His
    work on Agricultural Chemistry                                 358




    Octr. 19{th}

   When Potash was introduced into a tube having a platina wire
   attached to it so & fixed into the tube so as to be a conductor
   ie. so as to contain just water enough though solid--& inserted
   over mercury, when the Platina was made neg--No gas was formed
   & the mercury became oxydated--& a small quantity of the
   athalyer was produced around the plat: wire as was evident from
   its gassy alteration by the action of water

   --When the mercury was made the neg: gas was developed in great
   quantities from the pos: wire, & some from the neg mercury & this
   gas proved to be pure? _oxygene_ Capil Expr.--

   proving the decompr of _Potash_

London, Published by Henry Colburn & Richard Bentley 1831

  [Illustration]




    THE LIFE
    OF
    SIR HUMPHRY DAVY,
    BART. &c. &c.




CHAPTER I.

   Birth and family of Sir H. Davy.--Davy placed at a preparatory
   school.--His peculiarities when a boy.--Anecdotes.--He is
   admitted into the grammar-school at Penzance.--Finishes his
   education under Dr. Cardew at Truro.--Death of his father.--He
   is apprenticed by his mother to Mr. John Bingham Borlase, a
   surgeon and apothecary.--He enters upon the study of Chemistry,
   and devotes more time to Philosophy than to Physic.--The
   influence of early impressions illustrated.--His poetical
   talent.--Specimens of his versification.--An Epic Poem composed
   by him at the age of twelve years.--His first original
   experiment in chemistry.--He conceives a new theory of heat and
   light.--His ingenious experiment to demonstrate its truth.--He
   becomes known to Mr. Davies Gilbert, the founder of his future
   fortunes.--Mr. Gregory Watt arrives at Penzance, and lodges in
   the house of Mrs. Davy.--The visit of Dr. Beddoes and Professor
   Hailstone to Cornwall.--The correspondence between Dr. Beddoes
   and Mr. Davies Gilbert, relative to the Pneumatic Institution
   at Bristol, and the proposed appointment of Davy.--His final
   departure from his native town.


Humphry Davy was born at Penzance, in Cornwall, on the 17th of
December 1778.[1] His ancestors had long possessed a small estate
at Varfell, in the parish of Ludgvan, in the Mount's Bay, on which
they resided: this appears from tablets in the church, one of
which bears a date as far back as 1635. We are, however, unable to
ascend higher in the pedigree than to his paternal grandfather, who
seems to have been a builder of considerable repute in the west of
Cornwall, and is said to have planned and erected the mansion of
_Trelissick_, near Truro, at present the property and residence of
Thomas Daniel, Esq.

  [1] I have been favoured by the Rev. C. Val. Le Grice, of
  Trereiffe, with the following extract from the Parish Register,
  kept at Madron:--"Humphry Davy, son of Robert Davy, baptized at
  Penzance, January 22, 1779." The house in which he was born has
  been pulled down and lately rebuilt.

His son, the parent of the illustrious subject of our history,
was sent to London, and apprenticed to a carver in wood, but, on
the death of his father, who, although originally a younger son,
had latterly become the representative of the family, he found
himself in the possession of a patrimony amply competent for the
supply of his limited desires, and therefore pursued his art rather
as an object of amusement than one of necessity: in the town and
neighbourhood of Penzance, however, there remain many specimens of
his skill; and I have myself seen several chimney-pieces curiously
embellished by his chisel.[2]

  [2] Soon after the days of Gibbons, the art of ornamental carving
  in wood began to decay, and it may now be considered as nearly
  lost. Its decline may be attributed to two causes. In the first
  place, to the change of taste in fitting up the interior of our
  mansions; and in the next, to the introduction of composition for
  the enrichment of picture-frames and other objects of ornament.
  "Robert Davy," says a correspondent, "has been considered in this
  neighbourhood as the LAST OF THE CARVERS, and from his small
  size, was generally called _The little Carver_."

I am not able to discover that he was remarkable for any
peculiarity of intellect; he passed through life without bustle,
and quitted it with the usual regrets of friends and relatives. The
habits, however, generally imputed to him were certainly not such
as would have induced us to anticipate a high degree of steadiness
in the son.

His wife, whose maiden name was Grace Millett, was remarkable for
the placidity of her temper, and for the amiable and benevolent
tendency of her disposition: she had been adopted and brought up,
together with her two sisters, under circumstances of affecting
interest, by Mr. John Tonkin, an eminent surgeon and apothecary in
Penzance; a person of very considerable natural endowments, and
whose Socratic sayings are, to this day, proverbial with many of
the older inhabitants.

To withhold a narrative of the circumstances that led Mr. Tonkin
to the adoption of these orphan children, would be a species
of historical fraud and literary injustice, by which the world
would not only lose one of those bright examples of pure and
disinterested benevolence, which cheer the heart and ornament
our nature, but the medical profession would be deprived of an
additional claim to that public veneration and regard, to which the
kind sympathy of its professors has so universally entitled it.

The parents of these children, having been attacked by a fatal
fever, expired within a few hours of each other: the dying
agonies of the surviving mother were sharpened by her reflecting
on the forlorn condition in which her children would be left;
for, although the Milletts were originally aristocratic
and wealthy, the property had undergone so many subdivisions,
as to have left but a very slender provision for the member of the
family to whom she had united herself.

The affecting appeal which Mrs. Millett is said to have addressed
to her sympathising friend, and medical attendant, was not made
in vain: on her decease, Mr. Tonkin immediately removed the
three children to his own house, and they continued under the
guardianship of their kind benefactor, until each, in succession,
found a home by marriage.

The eldest sister, Jane, was married to Henry Sampson, a
respectable watchmaker at Penzance; the youngest, Elizabeth, to
her cousin, Leonard Millett of Marazion; neither of whom had any
family. The second sister, Grace, was married to Robert Davy, from
which union sprang five children, two boys and three girls, the
eldest being Humphry, the subject of our memoir, and the second
son, John, now Dr. Davy, a Surgeon to the Forces, and a gentleman
distinguished by several papers in the Philosophical Transactions.

Humphry Davy was nursed by his mother, and passed his infancy
with his parents;[3] but his childhood, after they had removed
from Penzance to reside on their estate at Varfell, was spent
partly with them and partly with Mr. John Tonkin, who extended his
disinterested kindness from the mother to all her children, but
more especially to Humphry, who is said, when a child, to have
exhibited powers of mind superior to his years. I have spared no
pains in collecting materials for the illustration of the earlier
periods of his history; as, to estimate the magnitude of an object,
we must measure the base with accuracy, in order to comprehend the
elevation of its summit.

  [3] For these materials I acknowledge myself indebted to Dr.
  Penneck of Penzance, and to Mrs. Millett, Sir H. Davy's sister.
  The facts were communicated in letters to Lady Davy, by whom they
  were kindly placed at my disposal.

He was first placed at a preparatory seminary kept by a Mr.
Bushell, who was so struck with the progress he made, that he urged
his father to remove him to a superior school.

It is a fact worthy, perhaps, of being recorded, that he would
at the age of about five years turn over the pages of a book as
rapidly as if he were merely engaged in counting the number of
leaves, or in hunting after pictures; and yet, on being questioned,
he could generally give a very satisfactory account of the
contents. I have been informed by Lady Davy that the same faculty
was retained by him through life, and that she has often been
astonished, beyond the power of expression, at the rapidity with
which he read a work, and the accuracy with which he remembered it.
Mr. Children has also communicated to me an anecdote, which may
be related in illustration of the same quality. Shortly after Dr.
Murray had published his system of chemistry, Davy accompanied Mr.
Children in an excursion to Tonbridge, and the new work was placed
in the carriage. During the occasional intervals in which their
conversation was suspended, Davy was seen turning over the leaves
of the book, but his companion did not believe it possible that he
could have made himself acquainted with any part of its contents,
until at the close of the journey he surprised him with a critical
opinion of its merits.

The book that engaged his earliest attention was "The Pilgrim's
Progress," a production well calculated, from the exuberance of its
invention, and the rich colouring of its fancy, for seizing upon
the ardent imagination of youth. This pleasing work, it will be
remembered, was the early and especial favourite of Dr. Franklin,
who never alluded to it but with feelings of the most lively
delight.

Shortly afterwards, he commenced reading history, particularly that
of England; and at the age of eight years he would, as if impressed
with the powers of oratory, collect together a number of boys in
a circle, and mounting a cart or carriage that might be standing
before the inn near Mr. Tonkin's house, harangue them on different
subjects, and offer such comments as his own ideas might suggest.

He was, moreover, at this age, a great lover of the marvellous,
and amused himself and his schoolfellows by composing stories of
romance and tales of chivalry, with all the fluency of an Italian
improvisatore; and joyfully would he have issued forth, armed
_cap-à-pié_, in search of adventures, and to free the world of
dragons and giants.

In this early fondness for fiction, and in the habit of exercising
his ingenuity in creating imagery for the gratification of his
fancy, Davy and Sir Walter Scott greatly resembled each other.
The Author of Waverley, in his general preface to the late
edition of his novels, has given us the following account of this
talent. "I must refer to a very early period of my life, were I
to point out my first achievement as a tale-teller; but I believe
most of my old schoolfellows can still bear witness that I had
a distinguished character for that talent, at a time when the
applause of my companions was my recompense for the disgraces and
punishments which the future romance-writer incurred for being idle
himself, and keeping others idle, during hours that should have
been employed on our tasks." Had not Davy's talents been diverted
into other channels, who can say that we might not have received
from his inventive pen a series of romantic tales, as beautifully
illustrative of the early history of his native country as are the
Waverley Novels of that of Scotland? for Cornwall is by no means
deficient in elfin sprites and busy "_piskeys_;" the invocation is
alone required to summon them from their dark recesses and mystic
abodes.

Davy was also in the frequent habit of writing verses and ballads;
of making fireworks, and of preparing a particular detonating
composition, to which he gave the name of "Thunder-powder," and
which he would explode on a stone to the great wonder and delight
of his young playfellows.

Another of his favourite amusements may also be recorded in this
place; for, however trifling in itself the incident may appear,
to the biographer it is full of interest, as tending to show the
early existence of that passion for experiment, which afterwards
rose so nobly in its aims and objects, as the mind expanded with
the advancement of his years. It consisted in scooping out the
inside of a turnip, placing a lighted candle in the cavity, and
then exhibiting it as a lamp; by the aid of which he would melt
fragments of tin, obtained from the metallic blocks which commonly
lie about the streets of a coinage town, and demand from his
companions a certain number of pins for the privilege of witnessing
the operation.

At an early age, but I am unable to ascertain the exact period, he
was placed at the Grammar-School in Penzance, under the Rev. J. C.
Coryton; and whilst his father resided at Varfell, he lived with
Mr. Tonkin, except during the holidays, which he always spent with
his parents.

He was extremely fond of fishing; and I have been lately informed
by one of his earliest companions, that when very young he greatly
excelled in that art. "I have known him," says my correspondent,
"catch grey-mullet at Penzance Pier, when none of us could succeed.
The mullet is a very difficult fish to hook, on account of the
diminutive size of its mouth; but Davy adopted a plan of his own
contrivance. Observing that they always swam in shoals, he attached
a succession of pilchards to a string, reaching from the surface to
the bottom of the sea, and while his prey were swimming around the
bait, he would by a sudden movement of the string entangle several
of them on the hooks, and thus dexterously capture them."

As soon as he became old enough to carry a gun, a portion of his
leisure hours was passed in the recreation of shooting; a pursuit
which also enabled him to form a collection of the rare birds which
occasionally frequented the neighbourhood, and which he is said to
have stuffed with more than ordinary skill.

When at home, he frequently amused himself with reading and
sketching, and sometimes with caricaturing any thing which struck
his fancy; on some occasions he would shut himself up in his room,
arrange the chairs, and lecture to them by the hour together.

I have been informed by one of his schoolfellows, a gentleman
now highly distinguished for his literary attainments, that, in
addition to the amusements already noticed, he was very fond
of playing at "Tournament," fabricating shields and visors of
pasteboard, and lances of wood, to which he gave the appearance
of steel by means of black-lead. Thus equipped, the juvenile
combatants, like Ascanius and the Trojan youths of classic
recollection, would tilt at each other, and perform a variety of
warlike evolutions.

By this anecdote we are forcibly reminded of the early taste of
Sir William Jones, who, when a boy at Harrow School, invented a
political play, in which William Bennet, Bishop of Cloyne, and the
celebrated Dr. Parr, were his principal associates. They divided
the fields in the neighbourhood of Harrow, according to a map
of Greece, into states and kingdoms; each fixed upon one as his
dominion, and assumed an ancient name. Some of their schoolfellows
consented to be styled Barbarians, who were to invade their
territories and attack their hillocks, which they denominated
fortresses.[4]

  [4] Life of Sir William Jones, by Lord Teignmouth.

On one occasion, Davy got up a Pantomime; and I have very
unexpectedly obtained a fly-leaf, torn out of a Schrevelius'
Lexicon, on which the _Dramatis Personæ_, as well as the names
of the young actors, were registered, as originally cast. This
document appears so interesting, that I have thought it right to
place it on record.

    _Father_         Cunnack.
    _Harlequin_      Davy.
    _Clown_          ....[5]
    _Columbine_      Hichens.
    _Cupid_          Veale.
    _Fortuna_        Scobell.
    _Ben_            Billy Giddy.
    _Nurse_          Robyns.
    _Maccaroni_      Dennis.

  [5] Here, as Mrs. Ratcliffe would say, the Legend is so effaced
  by damp and time, as to be wholly illegible.

The performers, who, I believe, with one exception, are all living,
will perhaps find some amusement in examining how far their future
characters were shadowed forth on this occasion. At all events, I
feel confident that they will receive no small gratification at
having their recollections thus carried back to the joyous scenes
of boyhood, connected as they always are, and must ever be, with
the most delightful associations of our lives.

From Penzance school he went to Truro, in the year 1793, and
finished his education under the Rev. Dr. Cardew, a gentleman who
is distinguished by the number of eminent scholars with which he
has graced his country.

That he was quick and industrious in his school exercises, may
be inferred from an anecdote related by his sister, that "on
being removed to Truro, Dr. Cardew found him very deficient in
the qualifications for the Class of his age, but on observing
the quickness of his talents, and his aptitude for learning, he
did not place him in a lower form, telling him that by industry
and attention he trusted he might be entitled to keep the place
assigned to him; which," his sister says, "he did, to the entire
satisfaction of his master."

It is very natural that an anecdote so gratifying to the family
should have been deeply imprinted on their memory; but we must not
be surprised on finding that it did not make a similar impression
upon Dr. Cardew. From a letter lately addressed by that gentleman
to Mr. Davies Gilbert, the following is an extract:--"With respect
to our illustrious countryman, Sir H. Davy, I fear I can claim but
little merit from the share I had in his education. He was not long
with me; and while he remained I could not discern the faculties
by which he was afterwards so much distinguished; I discovered,
indeed, his taste for poetry, which I did not omit to encourage."
Dr. Cardew adds, "While engaged in teaching the classics, I was
anxious to discharge faithfully the duties of my profession to the
best of my ability; but I was certainly fortunate in having so many
good materials to work upon, and thus having only '_fungi vice
cotis_,' though '_exsors ipse secandi_.'"--To the truth of this
latter part of the Doctor's quotation, will his scholars willingly
subscribe? It may be fairly doubted how far Dr. Cardew was able
to descend into the shadowy regions of Maro, without the "_donum
fatalis virgæ_."

Mrs. Millett thinks that the deficiency just alluded to may be
attributed to Mr. Coryton, rather than to the inattention of her
brother; the former having, from his neglect as a master, given
very general dissatisfaction. From what I can learn, at this
distant period, of the character of Mr. Coryton, it appears at all
events, that the "_exsors ipse secandi_" could not have been justly
applied to him; and that, owing to an unfortunate aptness in the
name to a doggrel verse, poor Davy had frequently to smart under
his tyranny.

    "Now, Master Dàvy,
    Now, Sir, I hàve 'e,
    No one shall sàve 'e,
    Good Master Dàvy;"

when the master, suiting the action to the rhythm, inflicted upon
the hand of the unlucky scholar the verberations of that type and
instrument of pedagoguish authority--the flat ruler. Here we have
another example of the seduction of sound, argued by our great
jurist Mr. Bentham,[6] to have determined the maxims of that law,
which has been pronounced by its sages the perfection of reason.

  [6] "Were the enquiry diligently made," he says, "it would be
  found that the Goddess of Harmony has exercised more influence,
  however latent, over the dispensations of Themis, than her
  most diligent historiographers, or even her most passionate
  panegyrists, seem to be aware of. Every one knows how, by the
  ministry of Orpheus, it was she who first collected the sons
  of men beneath the shadow of the sceptre: yet in the midst of
  continual experience, men seem yet to learn with what successful
  diligence she laboured to guide it in its course."

From a letter, however, written by Davy a few years afterwards,
respecting the education of a member of his family, he would appear
to have entertained an opinion not very unlike that of John Locke;
for, although he testifies the highest respect for Dr. Cardew, he
seems to consider the comparative idleness of his earlier school
career, by allowing him to follow the bent of his own mind, to have
favoured the developement of his peculiar genius. "After all," he
says, "the way in which we are taught Latin and Greek, does not
much influence the important structure of our minds. I consider
it fortunate that I was left much to myself as a child, and put
upon no particular plan of study, and that I enjoyed much idleness
at Mr. Coryton's school. I perhaps owe to these circumstances the
little talents I have, and their peculiar application:--what I am I
have made myself--I say this without vanity, and in pure simplicity
of heart."

His temper during youth is represented as mild and amiable. He
never suppressed his feelings, but every action was marked by
ingenuousness and candour, qualities which endeared him to his
youthful associates, and gained him the love of all who knew him.
"Nor can I find," says his sister, "beloved as he must have been by
my mother, that she showed him any particular preference;--all her
children appeared to be alike her care, and all alike shared her
affection."

In 1794, Mr. Davy died. We cannot but regret that he did not live
long enough to witness his son's eminence; for life, as Johnson
says, has few better things to give than a talented son; but from
his widow, who has but lately descended to the tomb, full of years
and respectability, this boon was not withheld, she witnessed his
whole career of usefulness and honour, and happily closed her eyes
before her maternal fears could have been awakened by those signs
of premature decay, which for some time had excited in his friends,
and in the friends of science, an alarm which the recent deplorable
event has too fatally justified.

In the year following the decease of her husband, Mrs. Davy, who
had again taken up her residence in Penzance, apprenticed her
son,[7] by the advice of her long-valued friend, Mr. Tonkin, to Mr.
John Bingham Borlase, at that time a surgeon and apothecary, but
who afterwards obtained a diploma, and became an eminent physician
at Penzance. Davy, however, for the most part, continued to pursue
his own plans of study; for although his friend Mr. Tonkin, without
doubt, intended him for a general practitioner in his native town,
yet he himself always looked forward to graduation at Edinburgh, as
a preliminary measure to his practising in the higher walk of his
profession.

  [7] The original indenture, now in the possession of Mr. R.
  Edmonds, solicitor, of Penzance, is dated February 10th, 1795.

His mind had, for some time, been engrossed with philosophical
pursuits; but until after he had been placed with Mr. Borlase, it
does not appear that he indicated any decided turn for chemistry,
the study of which he then commenced with all the ardour of his
temperament; and his eldest sister, who acted as his assistant,
well remembers the ravages committed on her dress by corrosive
substances.

It has been said that his mind was first directed to chemistry by
a desire to discover various mixtures as pigments: a suggestion
to which, I confess, I am not disposed to pay much attention;
for although he might have sought by new combinations to impart
a novel and vivid richness of colouring to his drawings, it was
the character of his mind to pursue with ardour every subject of
novelty, and to get at results by his own native powers, rather
than by the recorded experience of others.

I must here relate an anecdote, in illustration of this statement,
which has been lately communicated to me by the Reverend Dr.
Batten, the principal of the East India College at Hayleybury.
This gentleman was one of the earliest of Davy's schoolfellows,
but as he advanced in age, different views, and a different plan
of education, carried him to a distant part of the kingdom; the
discipline and duties of a cloistered school necessarily estranged
him from his native town; and it was not until after his admission
at Cambridge, and the arrival of the long vacation, which afforded
a temporary oblivion of academic cares, that Mr. Batten returned
to Cornwall, to revisit the scenes, and to renew the friendships
of his boyish days. Davy, who was at that period an apprentice to
Mr. Borlase, received him with transport and affection; but he
was no longer the boy that his friend had left him; he had become
more serious and contemplative, fond of solitary rambles, and
averse to enter into society, or to join the festive parties of the
inhabitants. In fact, his mind was now in the act of being moulded
by the spirit of Nature; and, without the constraint of study, he
was insensibly inhaling knowledge with the wild breezes of his
native hills.

In the course of conversation, Mr. Batten spoke of his academic
studies; and in alluding to the principles of Mechanics, to which
he had lately paid much attention, he expressed himself more
particularly pleased with that part which treats of "the Collision
of Bodies." What was his surprise, on finding Davy as well, if not
better acquainted with its several propositions! It was true that
he had never systematically studied the subject--had never perhaps
seen any standard work upon it, but he had instituted experiments
with elastic and inelastic balls, and had worked out the results by
the unassisted energies of his own mind. It is clear that, had this
branch of science not existed, Davy would have created it.

During this period of his apprenticeship, he twice a week attended
a French school in Penzance, kept by a M. Dugast, a priest from La
Vendée; and it was remarked that, although he acquired a knowledge
of the grammatical construction of the language with greater
facility than any of the other scholars, he could not succeed
in obtaining the pronunciation; and, in fact, notwithstanding
his extensive intercourse with foreigners, and his residence in
France, he never, even in after life, could pronounce French with
correctness or speak it with fluency.

While with Mr. Borlase, it was his constant custom to walk in the
evening to Marazion, to drink tea with an aunt to whom he was
greatly attached. Upon such occasions, his usual companion was a
hammer, with which he procured specimens from the rocks on the
beach. In short, it would appear that, at this period, he paid much
more attention to Philosophy than to Physic; that he thought more
of the bowels of the earth, than of the stomachs of his patients;
and that, when he should have been bleeding the sick, he was
opening veins in the granite. Instead of preparing medicines in the
surgery, he was experimenting in Mr. Tonkin's garret, which had
now become the scene of his chemical operations; and, upon more
than one occasion, it is said that he produced an explosion, which
put the Doctor, and all his glass bottles, in jeopardy. "This boy
Humphry is incorrigible!"--"Was there ever so idle a dog!"--"He
will blow us all into the air!" Such were the constant exclamations
of Mr. Tonkin; and then, in a jocose strain, he would speak of him
as the "Philosopher," and sometimes call him "Sir Humphry," as if
prophetic of his future renown.[8]

  [8] Davy appears to have been more fortunate than his prototype
  Scheele; for on one occasion, as the latter was employed in
  making pyrophorus, a fellow apprentice, without his knowledge,
  put some fulminating powder into the mixture; the consequence was
  a violent explosion; the whole family was thrown into confusion,
  and the young chemist was severely chastised.

His sister has remarked that, as he advanced in life, he always
preferred the society of persons older than himself; and one of his
contemporaries informs me that he never heard him allude to any
subject of science, although he remembers that while one of his
pockets was filled with fishing-tackle, the other was as commonly
loaded with specimens of rocks. With those, however, who were
superior to him in years, he delighted to enter into discussion.
At Penzance, there still resides a member of the Society of
Friends, whose ingenuity entitles him to greater rewards than a
provincial town can afford, with whom Davy, as a boy, was in the
constant habit of discussing questions of practical mechanics. "I
tell thee what, Humphry," exclaimed the Quaker upon one of these
occasions--"thou art the most quibbling hand at a dispute I ever
met with in my life."

For the surgical department of the profession, he always
entertained a decided distaste, although the following extract
from a letter of my correspondent Mr. Le Grice will show that,
for once at least, he had the merit of mending a broken head.
"The first time I ever saw Davy was on the Battery rocks; we were
alone bathing, and he pointed out to me a good place for diving;
at the same time he talked about the tides, and Sir Isaac Newton,
in a manner that greatly amazed me. I perhaps should not have so
distinctly remembered him, but on the following day, by not exactly
marking the spot he had pointed out, I was nearly killed by diving
on a rock, and he came as Mr. Borlase's assistant to dress the
wound."

It was his great delight to ramble along the sea-shore, and often,
like the orator of Athens, would he on such occasions declaim
against the howling of the wind and waves, with a view to overcome
a defect in his voice, which, although only slightly perceptible
in his maturer age, was in the days of his boyhood exceedingly
discordant. I may be allowed to observe, that the peculiar
intonation he employed in his public addresses, and which rendered
him obnoxious to the charge of affectation, was to be referred
to a laborious effort to conceal this natural infirmity. It was
also clear that he was deficient in that quality which is commonly
called "a good ear," and with which the modulation of the voice is
generally acknowledged to have an obvious connexion. Those who knew
him intimately will readily bear testimony to this fact. Whenever
he was deeply absorbed in a chemical research, it was his habit to
hum some tune, if such it could be called, for it was impossible
for any one to discover the air he intended to sing: indeed, Davy's
music became a subject of raillery amongst his friends; and Mr.
Children informs me, that, during an excursion, they attempted to
teach him the air of 'God save the King,' but their efforts were
unavailing.

It may be a question how far the following fact, with which I
have just been made acquainted, admits of explanation upon this
principle. On entering a volunteer infantry corps, commanded by
a Captain Oxnam, Davy could never emerge from the awkward squad;
no pains could make him keep the step; and those who were so
unfortunate as to stand before him in the ranks, ought to have been
heroes invulnerable in the heel. This incapacity, as may be readily
supposed, occasioned him considerable annoyance, and he engaged a
serjeant to give him private lessons, but it was all to no purpose.
In the platoon exercise he was not more expert; and he whose
electric battery was destined to triumph over the animosity of
nations, could never be taught to shoulder a musket in his native
town.

That Davy, in his youth, possessed courage and decision, may be
inferred from the circumstance of his having, upon receiving a
bite from a dog supposed to be rabid, taken his pocket-knife, and
without the least hesitation cut out the part on the spot, and then
retired into the surgery and cauterized the wound; an operation
which confined him to Mr. Tonkin's house for three weeks. The
gentleman from whom I received an account of this adventure, the
accuracy of which has been since confirmed by Davy's sister, also
told me, that he had frequently heard him declare his disbelief
in the existence of pain whenever the energies of the mind were
directed to counteract it; but he added, "I very shortly afterwards
had an opportunity of witnessing a practical refutation of this
doctrine in his own person; for upon being bitten by a conger eel,
my young friend Humphry roared out most lustily."

The anecdote of Davy's excising the bitten part with so much
promptitude and coolness, derives its interest from the age and
inexperience of the operator. In the course of his practice, every
physician must have met with similar cases of stern decision; but
I will venture to say that they have never occurred except in
instances of persons of acknowledged courage. Not many days since,
a veteran officer, distinguished for the intrepidity with which he
rescued the person of George the Third from the fury of a desperate
mob, in St. James's Park, informed me that he had formerly been
bitten at Vienna by a dog afterwards ascertained to have been
rabid; he immediately entered a blacksmith's shop, and by threats
compelled the person at the forge to heat an iron red-hot, and burn
his leg to the bone. The blacksmith, after first stipulating that
he should strap his eccentric customer to the anvil, reluctantly
complied; and my friend showed me a scar which sufficiently
testified the complete manner in which the son of Vulcan had
performed his engagement:--But to return from this digression.

At this time of day, no one can surely believe with Pope, that a
"Ruling Passion" is an innate and irresistible affection antecedent
to reason and observation: on the contrary, ample experience has
led us to the conclusion, that

            ----"men's judgments are
    A parcel of their fortunes, and things outward
    Do draw the inward quality after them."

The prevailing bias of great minds may thus be often traced to
some accidental, and apparently trivial, impression in early life;
and the acute biographer, in the course of his observations, will
continually discover traits of character that are readily referable
to such a source, even as in the magical colouring of Rembrandt's
works, the practised eye will recognize the _chiaro-oscuro_ of his
father's mill, in which the artist passed his hours of childhood.

In like manner, that marked aversion to arbitrary power, which
ever distinguished the actions and writings of Dr. Franklin, has
by himself been referred to the sense of injustice early imprinted
upon his mind by the severe and tyrannical conduct of his elder
brother; while, at the same time, he tells us that he was indebted
for his habit through life, of forming just estimates of the value
of things, to his having, at the age of seven years, "paid too much
for his whistle."

But circumstances, however disposed and happily combined, although
they may direct, can never create genius; it is possible that
Cowley might never have been enamoured of the Muses, nor Sir Joshua
Reynolds have courted the Graces, but for the casual circumstances
recorded by the biographer; and Ferguson might not have turned his
attention to mechanical inventions, had not an accident befallen
the roof of his father's cottage; and even Priestley, the founder
of a new and beautiful department in science, might very probably
never have been led to think of pneumatic chemistry, had he not
lived in the vicinity of a great brewery: still, however, such men
could not have shone dimly, if true genius be correctly defined
by Dr. Johnson as "a mind of large general powers accidentally
determined to some particular direction."[9]--So with Davy; his
mind was as vigorous as it was original, and no less logical and
precise than it was daring and comprehensive; nothing was too
mighty for its grasp, nothing too minute for its observation; like
the trunk of the elephant, it could tear up the oak of the forest,
or gently pluck the acorn from its branch.

  [9] M. de Bourrienne, in his "Private Memoirs of Napoleon
  Buonaparte," appears to have justly appreciated the influence
  of circumstances upon the destinies of great men. In speaking
  of Buonaparte at the Military College of Brienne, he says, "If
  the monks, to whom the superintendence of the establishment was
  confided, had engaged more able mathematical professors, or if
  we had had any excitement to the study of Chemistry, or Natural
  Philosophy, I am convinced that Buonaparte would have pursued
  those sciences with all the genius and spirit of investigation,
  which he displayed in a career more brilliant, it is true, but
  far less useful to mankind."

That circumstances in early life should have directed such energies
to a science, which requires for its advancement all the aids of
novel and bold, and yet patient and accurate research, is one of
those fortunate events which every unprejudiced mind will view with
triumph.

It is surely not difficult to understand how it happened that a
mind endowed with the genius and sensibilities of Davy, should have
been directed to the study of Chemistry and Mineralogy, when we
consider the nature and scenery of the country in which accident
had placed him. Many of his friends and associates must have been
connected with mining speculations: "Shafts," "Cross Courses," and
"Lodes," were words familiarised to his ears; and his native love
of enquiry could not have long suffered them to remain strangers
to his understanding. Nor could he have wandered along the rocky
coast, or have reposed for a moment to contemplate its wild
scenery, without being invited to geological enquiry by the genius
of the place; for were we to personify the science, where could we
find a more appropriate spot for her "local habitation?" "How often
when a boy," said Davy to me, on my showing him a drawing of the
wild rock scenery of Botallack Mine, "have I wandered about those
rocks in search of new minerals, and, when fatigued, sat down upon
the turf, and exercised my fancy in anticipations of scientific
renown!"

Such scenery, also, in one who possessed a quick sensibility
to the sublime forms of Nature, was well calculated to kindle
that enthusiasm which is so essential to poetical genius; and we
accordingly learn, that he became enamoured of the Muses at a very
early age, and evinced his passion by several poetical productions.
I am assured by Dr. Batten that, at the age of twelve years, he
had finished an epic poem, which he entitled the "Tydidiad," from
its celebrating the adventures of Diomede on his return from the
Trojan war. It is much to be regretted that not even a fragment of
this poem should have been preserved; but Dr. Batten well remembers
that it was characterised by great freedom of invention, vigour of
description, and wildness of execution.

At the age of seventeen he became desperately enamoured of a
young French lady, at that time resident at Penzance, to whom
he addressed numerous sonnets; but these, like the passion that
produced them, have long since been extinct.

Several of his minor productions were printed in a work entitled
the "Annual Anthology," published in three volumes at Bristol,
in 1799; two of which were edited by Southey, and one by James
Tobin;--a work of some curiosity, independent of its merits, as the
first attempt in this country to establish an "Annual," a species
of literary composition which has lately been made very popular and
amusing.

These volumes have now become extremely scarce, for which, and
other reasons, I have thought it right to place Davy's productions
on record in these memoirs; for although they are marked by the
common faults of youthful poets, they still bear the stamp of lofty
genius. There is, besides, a vein of philosophical contemplation
running through their composition, which may be considered as
indicating the future character and pursuit of their author; an
ardent aspiration after fame seems, even at this early period, to
have been felt in all its force, and is expressed in many striking
and beautiful passages.

There is still a higher motive by which I am induced to introduce
these specimens into my memoir, that of showing the bias of his
genius at this early period, with a view to compare it with that
which displayed itself in the "last days of the philosopher." We
shall find that the bright and rosy hues of fancy which gilded the
morning of his life, and were subdued or chased away by the more
resplendent light of maturer age, again glowed forth in the evening
of his days, and illumined the setting, as they had the dawning of
his genius.

His first production bears the date of 1795, and is entitled


THE SONS OF GENIUS.

    Bright bursting through the awful veil of night
      The lunar beams upon the Ocean play,
    The watery billows shine with trembling light,
      Where the swift breezes skim along the sea.

    The glimmering stars in yon ethereal plain
      Grow pale, and fade before the lucid beams,
    Save where fair Venus, shining o'er the main
      Conspicuous, still with fainter radiance gleams.

    Clear is the azure firmament above,
      Save where the white cloud floats upon the breeze,
    All tranquil is the bosom of the grove,
      Save where the Zephyr warbles through the trees.

    Now the poor shepherd wandering to his home
      Surveys the darkening scene with fearful eye,
    On every green sees little elfins roam,
      And haggard sprites along the moonbeams fly.

    While Superstition rules the vulgar soul,
      Forbids the energies of man to rise,
    Raised far above her low, her mean controul,
      Aspiring Genius seeks her native skies.

    She loves the silent solitary hours,
      She loves the stillness of the starry night,
    When o'er the brightening view Selene pours
      The soft effulgence of her pensive light.

    'Tis then disturb'd not by the glare of day;
      To mild tranquillity alone resign'd,
    Reason extends her animating sway
      O'er the calm empire of the peaceful mind.

    Before her lucid, all-enlightening ray,
      The pallid spectres of the Night retire,
    She drives the gloomy terrors far away,
      And fills the bosom with celestial fire.

    Inspired by her, the Sons of Genius rise
      Above all earthly thoughts, all vulgar care;
    Wealth, power, and grandeur they alike despise,
      Enraptured by the good, the great, the fair.

    A thousand varying joys to them belong--
      The charms of Nature and her changeful scenes;
    Their's is the music of the vernal song,
      And their's the colours of the vernal plains.

    Their's is the purple-tinged evening ray,
      With all the radiance of the morning sky;
    Their's is the splendour of the risen day,
      Enshrined in glory by the sun's bright eye.

    For them the Zephyr fans the odorous gale,
      For them the warbling streamlet softly flows,
    For them the Dryads shade the verdant vale,
      To them sweet Philomel attunes her woes.

    To them no wakeful moonbeam shines in vain
      On the dark bosom of the trackless wood,
    Sheds its mild radiance o'er the desert plain,
      Or softly glides along the chrystal flood.

    Yet not alone delight the soft and fair,
      Alike the grander scenes of Nature move;
    Yet not alone her beauties claim their care,
      The great, sublime, and terrible, they love.

    The Sons of Nature, they alike delight
      In the rough precipice's broken steep,
    In the black terrors of the stormy night,
      And in the thunders of the threatening deep.

    When the red lightnings through the ether fly,
      And the white foaming billows lash the shores;
    When to the rattling thunders of the sky
      The angry Demon of the waters roars;

    And when, untouch'd by Nature's living fires,
      No native rapture fills the drowsy soul;
    Then former ages, with their tuneful lyres,
      Can bid the fury of the passions fall.

    By the blue taper's melancholy light,
      Whilst all around the midnight torrents pour,
    And awful glooms beset the face of Night,
      They wear the silent solitary hour.

    Ah, then, how sweet to pass the night away
      In silent converse with the Grecian page!
    Whilst Homer tunes his ever-living lay,
      Or reason listens to th' Athenian sage;

    To scan the laws of Nature, to explore
      The tranquil reign of mild Philosophy;
    Or on Newtonian wings sublime to soar
      Through the bright regions of the starry sky.

    Ah! who can paint what raptures fill the soul
      When Attic Freedom rises to the war,
    Bids the loud thunders of the battle roll,
      And drives the tyrant trembling from her shore!

    From these pursuits the Sons of Genius scan
      The end of their creation; hence they know
    The fair, sublime, immortal hopes of man,
      From whence alone undying pleasures glow.

    By Science calm'd, over the peaceful soul,
      Bright with eternal Wisdom's lucid ray,
    Peace, meek of eye, extends her soft controul,
      And drives the fury Passions far away.

    Virtue, the daughter of the skies supreme,
      Directs their life, informs their glowing lays--
    A steady friend; her animating beam
      Sheds its soft lustre o'er their latter days.

    When life's warm fountains feel the frost of time;
      When the cold dews of darkness close their eyes,
    She shows the parting soul, upraised sublime,
      The brighter glories of her kindred skies.

    Thus the pale Moon, whose pure celestial light
      Has chased the gloomy clouds of Heaven away,
    Rests her white cheek, with silver radiance bright,
      On the soft bosom of the Western sea.

    Lost in the glowing wave, her radiance dies;
      Yet, while she sinks, she points her ling'ring ray
    To the bright azure of the orient skies--
      To the fair dawning of the glorious day.

    Like the tumultuous billows of the sea
      Succeed the generations of mankind;
    Some in oblivious silence pass away,
      And leave no vestige of their lives behind.

    Others, like those proud waves which beat the shore,
      A loud and momentary murmur raise;
    But soon their transient glories are no more,--
      No future ages echo with their praise.

    Like yon proud rocks amidst the sea of time,
      Superior, scorning all the billows' rage,
    The living Sons of Genius stand sublime,
      Th' immortal children of another age.

    For those exist whose pure ethereal minds,
      Imbibing portions of celestial day,
    Scorn all terrestrial cares, all mean designs,
      As bright-eyed eagles scorn the lunar ray.

    Their's is the glory of a lasting name,
      The meed of Genius and her living fires,
    Their's is the laurel of eternal fame,
      And their's the sweetness of the Muse's lyres.

    D.--1795.


THE SONG OF PLEASURE.

        The genial influence of the day
        Had chased the lingering cold away;
        Borne upon the Zephyr's wing,
        Sweetly smiled the radiant Spring:
        Her mild re-animating breath
        Wakes Nature from her wintry death;
        Attended by the laughing Hours,
        She rises clad in flowers,
        And lightly as she trips along,
        The vernal warblers raise the song.

        Rich in a thousand radiant dyes,
        Around her steps the flow'rets rise,
        The Zephyr sports, the sunbeams sleep
        On the blue bosom of the deep.
        And now, within my throbbing breast
        I feel the influence of the Spring,
        To ecstasy I tune my string,
        And garlanded with odorous flowers,
        I hasted to the shady grove,
        I hasted to the roseate bowers
        Where Pleasure dwells with Love.

        There Youth, and Love, and Beauty, bound
        The glowing rose my harp around;
        Then to the daughter of Desire,
        To bright-eyed Pleasure gave the lyre:
            She tuned the string,
      And smiling softer than the rosy sea,
    When the young Morning blushes on her breast,
      She raised the raptured lay,
            I heard her sing,
    The song lull'd every care and every thought to rest.

        Sons of Nature, hither haste,
        The blessings of existence taste;
        Listen to my friendly lay,
        And your cares shall fly away,
        Quick as fly the wintry snows
        When the vernal Zephyr blows.
        Let others, courting war's alarms,
        Seek the bloody field of arms;
        Let others, with undaunted soul,
        Bid Bellona's thunders roll;
        From the lightnings of their eye
        Let the trembling squadrons fly;
        Sons of Nature, you shall prove
        A softer fight, the fight of love.
        While you in soft repose are laid
        Underneath the myrtle shade,
        Amid the murky glooms of Death,
        The sons of battle pant for breath.

        Let the philosophic sage,
        His silver tresses white with age,
        Amid the chilling midnight damp,
        Waste the solitary lamp,
        To scan the laws of Nature o'er,
        The paths of Science to explore;
        Curb'd beneath his harsh controul
        The blissful Passions fly the soul.
        You, the gentler sons of joy,
        Softer studies shall employ!
        He to curb the Passions tries,
        You shall bid them all arise;
        His wants he wishes to destroy,
        You shall all your wants enjoy.
        Let the laurel, Virtue's meed,
        Crown his age-besilver'd head,
        The verdant laurel ever grows
        Amid the sullen Winter's snows:
        Let the rose, the flower of bliss,
        The soft unwrinkled temples kiss;
        Fann'd by the Zephyr's balmy wing,
        The odorous rose adorns the Spring.

        Let the Patriot die, to raise
        A lasting monument of praise.
        Ah, fool, to tear the glowing rose
        From the mirth-encircled brows,
        That around his dusky tomb
        The ever-verdant bay may bloom!
        Let Ambition's sons alone
        Bow around the tottering throne,
        Fly at Glory's splendid rays,
        And, moth-like, die amidst a blaze;
        You shall bow, and bow alone,
        Before delicious Beauty's throne.
        Lo! Theora treads the green,
        All breathing grace and harmony she moves,
        Fair as the mother of the Loves.
        In graceful ringlets floats her golden hair;
        From the bright azure of her eye
        Expression's liquid lightnings fly.
        Her cheek is fair,
        Fair as the lily, when, at dawning day,
        Tinged with the morning's bright and purple ray,
        Yonder scented groves among
        She will listen to your song.

        In yonder bower where roses bloom,
        Where the myrtle breathes perfume,
        You shall at your ease recline,
        And sip the soul-enlivening wine;
        There the lyre, with melting lay,
        Shall bid the soul dissolve away.
        Soft as the Morning sheds her purple light
        Through the dark azure of the Night,
        So soft the God of slumber sheds
        His roseate dews around your heads.

        Such the blessings I bestow!
        Haste, my sons, these blessings know!
        Behold the flow'rets of the Spring,
        They wanton in the Zephyr's wing,
        They drink the matin ether blue,
        They sip the fragrant evening dew.
        Man is but a short-lived flower,
        His bloom but for a changeful hour!
        Pass a little time away,
        The rosy cheek is turn'd to clay:
        No living joys, no transports burn
        In the dark sepulchral urn,
        No _Laurels_ crown the fleshless brows,
        They fade together with the _Rose_.

    D.--1796.


ODE TO SAINT MICHAEL'S MOUNT, IN CORNWALL.

    The sober eve with purple bright
    Sheds o'er the hills her tranquil light
      In many a lingering ray;
    The radiance trembles on the deep,
    Where rises rough thy rugged steep,
      Old Michael, from the sea.

    Around thy base, in azure pride,
    Flows the silver-crested tide,
      In gently winding waves;
    The Zephyr creeps thy cliffs around,--
    Thy cliffs, with whispering ivy crown'd,
      And murmurs in thy caves.

    Majestic steep! Ah, yet I love,
    With many a lingering step, to rove
      Thy ivied rocks among;
    Thy ivied, wave-beat rocks recall
    The former pleasures of my soul,
      When life was gay and young.

    Enthusiasm, Nature's child,
    Here sung to me her wood-songs wild,
      All warm with native fire;
    I felt her soul-awakening flame,
    It bade my bosom burn for fame,--
      It bade me strike the lyre.

    Soft as the Morning sheds her light
    Through the dark azure of the Night
      Along the tranquil sea;
    So soft the bright-eyed Fancy shed
    Her rapturing dreams around my head,
      And drove my cares away.

    When the white Moon with glory crown'd,
    The azure of the sky around,
      Her silver radiance shed;
    When shone the waves with trembling light,
    And slept the lustre palely bright
      Upon thy tower-clad head;

    Then BEAUTY bade my pleasure flow,--
    Then BEAUTY bade my bosom glow,
      With mild and gentle fire!
    Then Mirth, and Cheerfulness, and Love,
    Around my soul were wont to move,
      And thrill'd upon my lyre.

    But when the Demon of the deep
    Howl'd around thy rocky steep,
      And bade the tempests rise,--
    Bade the white foaming billows roar,
    And murmuring dash the rocky shore,
      And mingle with the skies;

    Ah, then my soul was raised on high,
    And felt the glow of ecstasy,
      With _great_ emotions fill'd;
    Thus Joy and Terror reign'd by turns,
    And now with LOVE the bosom burns,
      And now by FEAR is chill'd.

    Thus to the sweetest dreams resign'd,
    The fairy FANCY ruled my mind,
      And shone upon my youth;
    But now, to awful Reason given,
    I leave her dear ideal heaven
      To hear the voice of TRUTH.

    She claims my best, my loftiest song,
    She leads a brighter maid along--
      DIVINE PHILOSOPHY,
    Who bids the mounting soul assume
    Immortal Wisdom's eagle plume,
      And penetrating eye,

    Above Delusion's dusky maze,
    Above deceitful Fancy's ways,
      With roses clad to rise;
    To view a gleam of purest light
    Bursting through Nature's misty night,--
      The radiance of the skies.

    D.--1796.


THE TEMPEST.

    The Tempest has darken'd the face of the skies,
      The winds whistle wildly across the waste plain,
    The Fiends of the whirlwind terrific arise,
      And mingle the clouds with the white-foaming main.

    All dark is the night, and all gloomy the shore,
      Save when the red lightnings the ether divide,
    Then follows the thunder with loud-sounding roar,
      And echoes in concert the billowy tide.

    But though now all is murky and shaded with gloom,
      Hope, the soother, soft whispers the tempests shall cease;
    Then Nature again in her beauty shall bloom,
      And enamour'd embrace the fair sweet-smiling Peace;

    For the bright-blushing morning, all rosy with light,
      Shall convey on her wings the Creator of day;
    He shall drive all the tempests and terrors of night,
      And Nature enliven'd, again shall be gay.

    Then the warblers of Spring shall attune the soft lay,
      And again the bright flow'ret shall blush in the vale;
    On the breast of the Ocean the Zephyr shall play,
      And the sunbeam shall sleep on the hill and the dale.

    If the tempests of Nature so soon sink to rest--
      If her once-faded beauties so soon glow again,
    Shall Man be for ever by tempests oppress'd,
      By the tempests of passion, of sorrow, and pain?

    Ah, no! for his passions and sorrow shall cease
      When the troublesome fever of life shall be o'er;
    In the night of the grave he shall slumber in peace,
      And passion and sorrow shall vex him no more.

    And shall not this night and its long dismal gloom,
      Like the night of the tempest, again pass away?
    Yes! the dust of the earth in bright beauty shall bloom,
      And rise to the morning of heavenly day!

    D.--1796.


EXTRACT FROM AN UNFINISHED POEM ON MOUNT'S BAY.

    Mild blows the Zephyr o'er the Ocean dark,
    The Zephyr wafting the grey twilight clouds
    Across the waves, to drink the solar rays
    And blush with purple.
                          By the orient gleam
    Whitening the foam of the blue wave that breaks
    Around his granite feet, but dimly seen,
    Majestic Michael rises. He whose brow
    Is crown'd with castles, and whose rocky sides
    Are clad with dusky ivy: he whose base,
    Beat by the storm of ages, stands unmoved
    Amidst the wreck of things, the change of time.
    That base encircled by the azure waves,
    Was once with verdure clad: the tow'ring oaks
    There waved their branches green,--the sacred oaks
    Whose awful shades among, the Druids stray'd
    To cut the hallow'd miseltoe, and hold
    High converse with their Gods.
                                  On yon rough crag,
    Where the wild Tamarisk whistles to the sea blast,
    The Druid's harp was heard, swept by the breeze
    To softest music, or to grander tones
    Awaken'd by the awful master's hand.
    Those tones shall sound no more! the rushing waves,
    Raised from the vast Atlantic, have o'erwhelm'd
    The sacred groves. And deep the Druids lie
    In the dark mist-clad sea of former time.
    Ages had pass'd away, the stony altar
    Was white with moss, when on its rugged base
    Dire Superstition raised the gothic fane,
    And monks and priests existed.
                                  On the sea
    The sunbeams tremble; and the purple light
    Illumes the dark Bolerium,[10] seat of storms.
    High are his granite rocks. His frowning brow
    Hangs o'er the smiling Ocean. In his caves
    Th' Atlantic breezes murmur. In his caves,
    Where sleep the haggard Spirits of the storm,
    Wild dreary are the _schistine_[11] rocks around
    Encircled by the wave, where to the breeze
    The haggard Cormorant shrieks. And far beyond
    Are seen the cloud-like Islands, grey in mists.[12]

    Thy awful height, Bolerium, is not loved
    By busy Man, and no one wanders there
    Save he who follows Nature,--he who seeks
    Amidst thy crags and storm-beat rocks to find
    The marks of changes teaching the great laws
    That raised the globe from chaos; or he whose soul
    Is warm with fire poetic,--he who feels
    When Nature smiles in beauty, or sublime
    Rises in majesty,--he who can stand
    Unawed upon thy summit, clad in tempests,
    And view with raptured mind the roaring deep
    Rise o'er thy foam-clad base, while the black cloud
    Bursts with the fire of Heaven--
                                    He whose heart
    Is warm with love and mercy,--he whose eye
    Drops the bright tear when anxious Fancy paints
    Upon his mind the image of the Maid,
    The blue-eyed Maid who died beneath thy surge.
    Where yon dark cliff[13] o'ershadows the blue main,
    THEORA died amidst the stormy waves,
    And on its feet the sea-dews wash'd her corpse,
    And the wild breath of storms shook her black locks.
    Young was THEORA; bluer was her eye
    Than the bright azure of the moonlight night;
    Fair was her cheek as is the ocean cloud
    Red with the morning ray.
                              Amidst the groves,
    And greens, and nodding rocks that overhang
    The grey Killarney, pass'd her morning days
    Bright with the beams of joy.
                                  To solitude,
    To Nature, and to God, she gave her youth;
    Hence were her passions tuned to harmony.
    Her azure eye oft glisten'd with the tear
    Of sensibility, and her soft cheek
    Glow'd with the blush of rapture. Hence, she loved
    To wander 'midst the green-wood, silver'd o'er
    By the bright moonbeam. Hence, she loved the rocks
    Crown'd with the nodding ivy, and the lake
    Fair with the purple morning, and the sea
    Expansive mingling with the arched sky.
    Kindled by Genius, in her bosom glow'd
    The sacred fire of Freedom. Hence, she scorn'd
    The narrow laws of custom that control
    Her feeble sex. Great in her energies,
    She roam'd the fields of Nature, scann'd the laws
    That move the ruling atoms, changing still,
    Still rising into life. Her eagle eye,
    Piercing the blue immensity of space,
    Held converse with the lucid sons of Heaven,
    The day-stars of creation, or pursued
    The dusky planets rolling round the Sun,
    And drinking in his radiance light and life.
    Such was the Maiden! Such was she who fled
    Her native shores.
                      Dark in the midnight cloud,
    When the wild blast upon its pinions bore
    The dying shrieks of Erin's injured sons,[14]
    She 'scaped the murderer's arm.
                                    The British bark
    Bore her across the ocean. From the West
    The whirlwind rose, the fire-fraught clouds of Heaven
    Were mingled with the wave. The shatter'd bark
    Sunk at thy feet, Bolerium, and the white surge
    Closed on green Erin's daughter.

  [10] The Land's End in Cornwall.

  [11] The granite of Cornwall is generally found incumbent on
  primitive _schistus_. This is the case in many of the cliffs at
  the Land's End. The upper stratum is composed of granite, the
  lower with the surrounding rocks of _schistus_. D.

  [12] The Islands of Scilly.

  [13] A rock near the Land's End, called the 'Irish Lady.'

  [14] The Irish Lady was shipwrecked at the Land's End, about the
  time of the massacre of the Irish Protestants by the Catholics,
  in the reign of Charles the First.

That the Genius who presided over the destinies of Davy should
have torn him from these flowery regions of Fancy, and condemned
him to labour in the dusky caverns of the mineral kingdom, has
furnished a fruitful theme of lamentation to the band of Poets,
and to those who prefer the amusements to the profits of life, and
who cherish the hallucinations of the imagination rather than the
truths of science. If, however, we regret that Davy's Muse, like
Proserpine, should have been thus violently seized, and carried off
to the lower regions, as she was weaving her native wild flowers
into a garland, we may console ourselves in knowing that, like the
daughter of Ceres, she also obtained the privilege of occasionally
revisiting her native bowers; for it will appear in the course of
these memoirs, that in the intervals of more abstruse studies, Davy
not unfrequently amused himself with poetical composition. But, in
sober truth, is it possible that any reasonable being can regret
the course in which he has been impelled? A great poetic Genius has
said, "If Davy had not been the first Chemist, he would have been
the first Poet of his age." Upon this question I do not feel myself
a competent judge: but where is the modern Esau who would exchange
his Bakerian Lecture for a poem, though it should equal in design
and execution the PARADISE LOST?

As far as can be ascertained, one of the first original experiments
in Chemistry performed by him at Penzance, was for the purpose of
discovering the quality of the air contained in the bladders of
sea-weed, in order to obtain results in support of a favourite
theory of light; and to ascertain whether, as land vegetables are
the renovators of the atmosphere of land-animals, sea-vegetables
might not be the preservers of the equilibrium of the atmosphere of
the ocean. From these experiments he concluded, that the different
orders of the marine _Cryptogamia_ were capable of decomposing
water, when assisted by the attraction of light for oxygen.

His instruments, however, were of the rudest description,
manufactured by himself out of the motley materials which chance
threw in his way; the pots and pans of the kitchen, and even the
more sacred vessels and professional instruments of the surgery,
were without the least hesitation or remorse put in requisition.

While upon this subject, I will relate an anecdote which was
communicated to me by my late venerable friend Mr. Thomas
Giddy.[15] A French vessel having been wrecked off the Land's
End, the surgeon escaped, and found his way to Penzance; accident
brought him acquainted with Humphry Davy, who showed him many
civilities, and in return received, as a present from the surgeon,
a case of instruments which had been saved from the ship. The
contents were eagerly turned out and examined by the young chemist,
not, however, with any professional view as to their utility,
but in order to ascertain how far they might be convertible to
experimental purposes. The old-fashioned and clumsy glyster
apparatus was viewed with exultation, and seized in triumph!--What
reverses may not be suddenly effected by a simple accident! so
says the moralist. Reader, behold an illustration:--in the brief
space of an hour, did this long-neglected and unobtrusive machine,
emerging from its obscurity and insignificance, figure away in all
the pomp and glory of a complicated piece of pneumatic apparatus:
nor did its fortunes end here; it was destined for greater things;
and we shall hereafter learn that it actually performed the duties
of an air-pump, in an original experiment on the nature and sources
of heat. The most humble means may certainly accomplish the highest
ends: the filament of a spider's web has been used to measure the
motions of the stars; and a kite, made with two cross sticks and
a silk handkerchief, enabled the chemical Prometheus to rob the
thunder-cloud of its lightnings; but that a worn-out instrument,
such as has been just described, should have furnished him who was
born to revolutionize the science of the age, with the only means
of enquiry at that time within his reach, affords, it must be
admitted, a very whimsical illustration of our maxim.

  [15] I cannot allude to this name, without paying a tribute of
  respect to the memory of one who, for more than half a century,
  practised the profession of a surgeon in Penzance with as much
  credit to himself, as advantage to his neighbourhood.

Nor can we pass over these circumstances, without observing how
materially they must have influenced the subsequent success of
Davy as an experimentalist. Had he, at the commencement of his
career, been furnished with all those appliances which he enjoyed
at a later period, it is more than probable that he might never
have acquired that wonderful tact of manipulation, that ability of
suggesting expedients, and of contriving apparatus so as to meet
and surmount the difficulties which must ever beset the philosopher
in the unbeaten tracks of Science. In this art, he certainly
stands unrivalled, and, like his prototype Scheele,[16] or that
pioneer of pneumatic experimentalists, Dr. Priestley,[17] he was
unquestionably indebted for his address to the circumstances above
related. There never, perhaps, was a more striking exemplification
of the adage, that "necessity is the parent of invention."

  [16] Bergman, Professor of Upsal, was informed of a young man who
  resided in the house of an apothecary, and who was reproached
  for neglecting the duties of his profession, while he devoted
  the whole of his time to Chemistry. Bergman's curiosity was
  excited; he paid him a visit, and was astonished at the knowledge
  he displayed, and at the profound researches in which he was
  engaged, notwithstanding the poverty under which he laboured, and
  the restraint under which his situation placed him. He encouraged
  his ardour, and made him his friend. This young man was the
  celebrated _Scheele_.

  [17] No man ever entered upon an undertaking with less apparent
  means of success, than did Priestley upon that of Chemistry.
  He neither possessed apparatus, nor the money to procure it.
  These circumstances, which at first sight seem so adverse, were
  in reality those which contributed to his ultimate success.
  The branch of Chemistry he selected was new; an apparatus had
  to be invented before any important step could be taken; and
  as simplicity is essential in every research, he was likely to
  contrive the best whose circumstances obliged him to attend to
  economy.

It would however appear that, imperfect as must have been his
apparatus, and limited as were his resources, his ambition very
early led him to the investigation of the most abstruse and
recondite phenomena. He was not more than seventeen when he formed
a strong opinion adverse to the general belief in the existence of
_caloric_, or the materiality of heat.

As I shall hereafter have occasion to draw a parallel between the
intellectual qualities of Davy, and those of the celebrated Dr.
Black, the father of modern chemistry, it may not be irrelevant to
state, in this place, that the subject of heat was also amongst
the first that attracted the attention of this latter philosopher;
indeed, he tells us himself, that he "can scarcely remember the
time, when he had not some idea of the disagreement of facts with
the commonly received doctrines upon this subject." The tendency
of his mind, however, was in direct opposition to that of Davy's,
for he insisted upon the materiality of heat, and was the first
to conceive the bold idea of its being capable, like any other
substance, of entering into chemical combination with various
bodies, and of thus losing its characteristic qualities.

Black's theory could not be more opposed to that of Davy than
was his conduct upon the occasion; for, although an experiment
suggested itself to his mind, by which, as he thought, he could
at once establish the truth of his favourite doctrine, he delayed
performing it, because there did not happen to be an ice-house
in the town in which he lived. With Davy, on the other hand, the
conception and execution of an experiment were nearly simultaneous:
no sooner, therefore, had he formed his opinion, than his eager
spirit urged him to put it to the test.

Having procured a piece of clock-work, so contrived as to be
set to work in an exhausted receiver, he added two horizontal
plates of brass; the upper one, carrying a small metallic cup
to be filled with ice, revolved in contact with the lower one.
The whole machine, resting on a plate of ice, was covered by a
glass receiver, and the air was exhausted by the very syringe,
ingeniously modified for the purpose, with which the reader has
already been made acquainted: for, as yet, he had no air-pump, and,
what is still more worthy of notice, had never even seen one! The
machine was now set in motion, when the ice in the small cup was
soon observed to melt; whence he inferred that this effect could
alone proceed from vibratory motion, since the whole apparatus was
insulated from all accession of material heat, by the frozen mass
below, and by the vacuum around it.

The experiment was afterwards repeated with greater care, and by
means of a more refined apparatus: it was modified in different
ways; and the results were ultimately published in an Essay, to be
hereafter noticed, "On Heat, Light, and the Combinations of Light,"
which appeared in a provincial collection of tracts, edited by Dr.
Beddoes, at Bristol.

Mr. Davies Gilbert, in describing the above experiment in his late
address to the Royal Society, very justly observed that it does
not at all decide the important matter in dispute, with respect to
an ethereal or transcendental fluid; but that few young men remote
from the society of persons conversant with science, will present
themselves, who are capable of devising any thing so ingenious.

Dr. Henry, in a paper published in the "Memoirs of the Manchester
Society," on entering into a review of this and similar
experiments, very truly states, that the mode of insulation is not
only imperfect, but that, according to Count Rumford, caloric will
even pass through a Torricellian vacuum.

The most prominent circumstance in the history of this period of
Davy's life, is his introduction to Mr. Davies Giddy, now Mr.
Gilbert, the late distinguished and popular President of the
Royal Society. The manner in which this happened is as curious as
its result was important; and it furnishes another very striking
illustration of the power of simple accident in directing our
destinies. Mr. Gilbert's attention was attracted to the future
philosopher, as he was carelessly swinging over the hatch, or half
gate, of Mr. Borlase's house, by the humorous contortions into
which he threw his features. Davy, it may be remarked, when a boy,
possessed a countenance which, even in its natural state, was very
far from comely, while his round shoulders, inharmonious voice, and
insignificant manner, were calculated to produce any thing rather
than a favourable impression: in riper years, he was what might be
called "good-looking," although, as a wit of the day observed, his
aspect was certainly of the "Bucolic" character. The change which
his person underwent, after his promotion to the Royal Institution,
was so rapid, that, in the days of Herodotus, it would have been
attributed to nothing less than the miraculous interposition of
the Priestesses of Helen. A person, who happened to be walking
with Mr. Gilbert upon the occasion alluded to, observed that
the extraordinary-looking boy in question was young Davy, the
Carver's son, who, he added, was said to be fond of making chemical
experiments. "Chemical experiments!" exclaimed Mr. Gilbert, with
much surprise: "if that be the case, I must have some conversation
with him." Mr. Gilbert, as we all know, possesses a strong
perception of character, and he therefore soon discovered ample
evidence of the boy's singular genius. After several interviews,
which confirmed him in the opinion he had formed, he offered
young Humphry the use of his library, or any other assistance that
he might require for the pursuit of his studies; and at the same
time gave him an invitation to his house at Tredrea, of which he
frequently availed himself.

During one of his visits, Mr. Gilbert accompanied him to Hayle
Copper-House, and introduced him to Dr. Edwards, a gentleman
afterwards known to the medical profession as the chemical
lecturer in the school of St. Bartholomew's Hospital; at the time,
however, alluded to, he resided at Copper-House with his father,
and possessed a well-appointed laboratory. The tumultuous delight
which Davy expressed on seeing, for the first time, a quantity
of chemical apparatus, hitherto only known to him through the
medium of engravings, is described by Mr. Gilbert as surpassing
all description. The air-pump more especially fixed his attention,
and he worked its piston, exhausted the receiver, and opened its
valves, with the simplicity and joy of a child engaged in the
examination of a new and favourite toy.

It is a curious circumstance, that the phenomena resulting from the
contact of iron and copper, in the investigation of which Davy was
destined to perform so prominent a part, were very early noticed
by Mr. Edwards in this place; who found that the flood-gates in
the Port of Hayle decayed with a rapidity wholly inexplicable,
but upon the supposition of some _chemical_ action between the
metals which had not yet been clearly explained. How little did Mr.
Edwards imagine that the fact, which had so powerfully excited his
curiosity, would become to the youth before him, a future source of
rich and honourable discovery!

During the following year, an event occurred which contributed,
in no small degree, to the advancement of Davy's prospects. Mr.
Gregory Watt, who had long been in a declining state of health,
was recommended by his physicians to reside for some time in the
West of England, and he accordingly proceeded at once to Penzance,
and took up his abode, as a lodger and boarder, in the house of
Mrs. Davy. It may be supposed that two kindred spirits would not
be long in contracting an acquaintance with each other; in fact,
an intimacy of the warmest nature did ultimately grow up between
them, and continue to the very moment of Mr. Watt's premature
dissolution: the origin and progress of their friendship, however,
are too curious to be passed over without some notice.

Mr. Gregory Watt possessed a warm and affectionate heart; but
there was a solemn, aristocratic coldness in his manner, which
repulsed every approach to familiarity. Davy, it has been already
stated, did not at that time possess any of those qualifications,
in person or manner, which are calculated to produce favourable
prepossessions. It may, therefore, be readily imagined how Mr.
Watt must have felt, on finding the son of his landlady familiarly
addressing him on subjects of metaphysics and poetry. By one of
those strange perversions which have so frequently led great men
to conceal the peculiarity of their talents, and to rest their
claims to notice and respect upon qualifications which they
possessed only in an inferior degree, Davy sought to ingratiate
himself with Mr. Watt by metaphysical discussions; but, instead
of the admiration, he excited the disgust of his hearer. It was
by mere accident that an allusion was first made to chemistry,
when Davy flippantly observed, that he would undertake to demolish
the French theory in half an hour. He had touched the chord: the
interest of Mr. Watt was excited,--he conversed with Davy upon his
chemical pursuits,--he was at once astonished and delighted at his
sagacity,--the barrier of ice was removed, and they became attached
friends.

Mr. Wedgwood, and his brother Thomas, also spent a winter at
Penzance; and I have reason to believe that their friendship was of
substantial benefit to Davy.

Before I attend the progress of our philosopher to the next
scene of life, or proceed to detail the circumstances connected
with his departure from Penzance, I must relate the following
anecdote.--Until the formation of the Geological Society of
London occasioned the introduction of more extended and sounder
views into the science, geologists were divided into two great
rival sects,--into Neptunists and Plutonists: the one affirming
that the globe was exclusively indebted for its present form and
arrangement to the agency of water; the other, admitting to a
certain extent the operation of water, but maintaining the utter
impossibility of explaining the consolidation of the strata without
the intervention of fire. Every geologist felt bound to side with
the one or the other of these contending parties, for neutrality
was held as disgraceful as though the law of Solon had been in
active operation. I shall not easily forget the din and fury of
this elemental war, as it raged in Edinburgh when I was a student
in that University; even the mineral dealers, who, like the
artisans of a neutral city, sold arms and ammunition to both sides,
still defended their own opinions with party fury. It was amusing
to observe the triumph and dismay which, by turns, animated and
depressed each side, as the discovery of a new fact, or a fresh
specimen, appeared to give a preponderance to the doctrine of fire
or water. The fact of so large a portion of the strata being found
in the state of a carbonate was advanced by the Neptunists as an
unanswerable argument against igneous agency: the dismay therefore
which this sect received upon the discovery of Sir James Hall,
that under the combined forces of heat and compression, carbonate
of lime might be fused, was only equalled by the excessive joy
excited in the contending party. We may form some notion of the
high importance attached to this discovery, when we learn that its
author applied to the Government for a flag of truce to convey
illustrative specimens to the Continental philosophers.

It so happened, that the Professors of Oxford and Cambridge ranged
themselves under opposite banners: Dr. Beddoes was a violent and
uncompromising Plutonist, while Professor Hailstone was as decided
a Neptunist. The rocks of Cornwall, and their granitic veins, had
been appealed to, as affording evidence upon the subject; and the
two Professors, who, although adverse in opinion, were united
in friendship, determined to proceed together to the field of
dispute, each hoping that he might thus convince the other of
his error, and cure him of his heresy. The belligerents arrived
at Penzance, and in company with their mutual friend, Mr. Davies
Gilbert, examined the coast, and procured specimens with pretty
much the same spirit of selection as a schoolboy consults his
Gradus, not for an epithet of any meaning, but for one which best
suits his measure; and having made drawings, disputed obvious
appearances, rendered that which was clear to the senses, confused
to the understanding, and what was already confused, ten times
more obscure, they returned, the opinion of each, as might easily
have been anticipated, having been strengthened by the ordeal:
the one protesting that the very aspect of the shivered slate was
sufficient to prove that the globe must have been roasted to rags;
the other, with equal plausibility, declaring that there was not a
tittle of evidence to show that the watery solvent had ever even
simmered. Such, in fact, must ever be the case, when philosophers
examine the same subject under such different impressions, and in
such opposite points of view; like the two knights who could not
agree respecting the colour of the shield, only because each saw a
different side of it.

Rocks, it is said, have flinty hearts, and certain it is that, upon
this occasion, Cornwall did not afford that assistance against the
Neptunists, which the Oxford Professor had sought with so much zeal
and confidence; but if deferred revenge had, as we are told is
generally the case, been put out at compound interest, and Beddoes
had exacted its dues with more than judaical rigour, it must be
allowed that Cornwall, by placing Davy at his disposal, would have
fully cancelled all demands.

    Plutonian Beddoes, erst, in spiteful ire,
    To see a _Hailstone_ mock his central fire,
    A mighty spirit raised, by whose device
    We now burn HAILSTONES, and set fire to Ice.

Before quitting this subject, it is but justice to advert to the
progress which Geology has made since the turbulence of this
contest has subsided; it has grown strong in facts, and is daily
increasing its stores. It has been wisely said by one of the
ancient Poets, that in vehement disputes, not only the persons
engaged, but every one who is at all interested, must suffer; not
only the combatants, but the spectators of the combat,--for it
is difficult to apprehend truth while it is the subject of angry
contest.

To return to the narrative.--Upon Beddoes establishing the
"Pneumatic Institution" at Bristol, he required an assistant who
might superintend the necessary experiments in the laboratory;
and Mr. Gilbert proposed Davy as a person fully competent to fill
the situation. The young candidate had already produced a very
favourable impression upon Dr. Beddoes, by his experiments upon
Heat and Light, which he had some time before transmitted to him
through the hands of his friend Mr. Gregory Watt. This fact may
be collected from a note appended by Dr. Beddoes to Davy's paper
subsequently published in the first volume of the West Country
Contributions, in which the Doctor says, "My first knowledge of
Mr. Davy arose from a letter written in April 1798, containing an
account of his researches on Heat and Light." The rest is told in
the letters which passed on this occasion between Dr. Beddoes and
Mr. Gilbert, and from which I shall make such extracts as may be
necessary to complete the history of a transaction of much interest
and importance.

In a letter dated July 4, 1798, Dr. Beddoes says, "I am glad that
Mr. Davy has impressed you as he has me. I have long wished to
write to you about him, for I think I can open a more fruitful
field of investigation than any body else. Is it not also his
most direct road to fortune? Should he not bring out a favourable
result, he may still exhibit talents for investigation, and entitle
himself to public confidence more effectually than by any other
mode. He must be maintained, but the fund will not furnish a salary
from which a man can lay up any thing. He must also devote his
time for two or three years to the investigation. I wish you would
converse with him upon the subject. No doubt he has received my two
last letters. I am sorry I cannot at this moment specify a yearly
sum, nor can I say with certainty whether all the subscribers will
accede to my plan; most of them will, I doubt not. I have written
to the principal ones, and will lose no time in sounding them all."

In a second letter of the 18th of July, we find the following
observations. "I have received a letter from Mr. Davy since I wrote
to you. He has oftener than once mentioned a _genteel maintenance_,
as a preliminary to his being employed to superintend the
Pneumatic Hospital. I fear the funds will not allow an ample
salary; he must, however, be maintained. I can attach no idea to
the epithet _genteel_, but perhaps all difficulties would vanish
in conversation; at least, I think your conversing with Mr. Davy
will be a more likely way of smoothing difficulties, than our
correspondence. It appears to me, that this appointment will bear
to be considered as a part of Mr. Davy's medical education, and
that it will be a great saving of expense to him. It may also be
the foundation of a lucrative reputation; and certainly nothing
on my part shall be wanting to secure to him the credit he may
deserve. He does not undertake to discover cures for this or that
disease; he may acquire just applause by bringing out clear, though
negative results. During my journeys into the country, I have
picked up a variety of important and curious facts from different
practitioners. This has suggested to me the idea of collecting and
publishing such facts as this part of the country will, from time
to time, afford. If I could procure chemical experiments, that bore
any relation to organised nature, I would insert them. If Mr. Davy
does not dislike this method of publishing his experiments, I would
gladly place them at the head of my first volume, but I wish not
that he should make any sacrifice of judgment or inclination."

It remains only to be stated, that Mr. Gilbert kindly undertook
the negotiation, and completed it to the satisfaction of all the
principal parties. Mrs. Davy yielded to her son's wishes, and
Mr. Borlase very generously surrendered his indenture, with an
endorsement to the following effect,--that he freely gave up the
indenture, on account of the singularly promising talents which Mr.
Davy had displayed.

His old and valued friend Mr. Tonkin, however, not only expressed
his disapprobation of this scheme, but was so vexed and irritated
at having his favourite plan of fixing Davy in his native town as
a Surgeon, thus thwarted, that he actually altered his will, and
revoked the legacy of his house which he had previously bequeathed
him. Mr. Tonkin died on the 24th of December 1801; so that,
although he lived long enough to witness Davy's appointment to the
Royal Institution, he could never have anticipated the elevation to
which his genius and talents ultimately raised him.

On the 2nd of October in the year 1798, Davy quitted Penzance,
before he had attained his twentieth year. Mr. Gilbert well
remembers meeting him upon his journey to Bristol, and breakfasting
with him at Okehampton, on the 4th of October. He was in the
highest spirits, and in that frame of mind in which a man of ardent
imagination identifies every successful occurrence with his own
fortunes; his exhilaration, therefore, was not a little heightened
by the arrival of the mail-coach from London, covered with laurels
and ribbons, and bringing the news, so cheering to every English
heart, of NELSON'S glorious victory of the NILE.




CHAPTER II.

   Cursory thoughts on the advantages of Biography.--Plan
   and objects of the Pneumatic Institution.--Davy contracts
   friendships during his residence at Bristol.--His first visit
   to London.--His Letters to Mr. Davies Gilbert.--The publication
   of the West Country Contributions, by Dr. Beddoes.--Davy's
   Essays on Heat, Light, and Respiration.--His interesting
   experiments on bonnet canes.--He commences an enquiry into
   the nature of nitrous oxyd.--He publishes his chemical
   researches.--A critical examination of the work.--Testimony of
   Tobin, Clayfield, Southey, and others, respecting the powers
   of nitrous oxyd.--Davy breathes carburetted hydrogen gas, and
   nearly perishes from its effects.--His new Galvanic experiments
   communicated in a Letter to Mr. Gilbert.


Having concluded the early history of the subject of these
memoirs, and conducted it to that memorable day on which he left
his native town, and bursting from obscurity, prepared to enter
upon a wider field of usefulness and honour, I shall accompany
him in his progress; and with the honest desire of affording
instruction as well as amusement,--for history is useful only as it
holds up the mirror of Truth,--I shall continue to point out the
various circumstances that may have contributed to his success and
scientific renown; and to offer such occasional reflections as may
be likely to illustrate not only the superficial peculiarities
which constitute the light and shade of character, but those deeper
varieties of mind, upon which the superiority of intellect may be
supposed to depend.

After all, the great end of biography is not to be found, as some
would seem to imagine, in a series of dates, or in a collection
of gossiping anecdotes and table-talk, which, instead of lighting
up and vivifying the features, hang as a cloud of dust upon the
portrait; but it is to be found in an analysis of human genius, and
in the developement of those elements of the mind, to whose varied
combinations, and nicely adjusted proportions, the mental habits,
and intellectual peculiarities of distinguished men may be readily
referred.

It has been stated that an arrangement had been concluded between
Dr. Beddoes and Davy: it is but an act of justice to say, that it
was of a liberal and honourable description; and let me also add in
this place, that no sooner had Davy found himself in a situation
which secured for him the necessaries of life, than he renounced
all claims upon his paternal property, in favour of his mother and
sisters.

By acceding to the proposal of Dr. Beddoes, he never intended to
abandon the profession in which he had embarked; on the contrary,
he persevered in his determination to study and graduate at
Edinburgh, and his patron promised that every opportunity should be
afforded him at Bristol for seeing medical practice: this part of
the arrangement, however, was voluntarily abandoned by him, for he
soon became so absorbed by the labours of the laboratory, as to
leave little leisure for the clinical studies of the hospital.

The Pneumatic Institution was established for the purpose of
investigating the medical powers of factitious airs or gases; and
to Davy was assigned the office of superintending the various
experiments.

It is now generally acknowledged, that the Art of Physic has not
derived any direct advantage from the application of a class of
agents which, undoubtedly, held forth the fairest promise of
benefit; but it is too frequently the case, that in physic, theory
and experience are in open hostilities with each other. The gases
are now never employed in the treatment of disease, except by a
few crafty or ignorant empirics, whose business it is to enrich
themselves by playing on the credulity of mankind: indeed, we may
say of popular remedies in general what M. de Lagrange has so
wittily said of popular prejudices, that they are the cast-off
clothes of philosophers, in which the rabble dress themselves.

The investigation, however, into the nature and composition of
the gases paved the way to some new and important discoveries in
science; so that, to borrow a Baconian metaphor, although our
philosophers failed in obtaining the treasure for which they so
eagerly dug, they at least, by turning up and pulverizing the soil,
rendered it fertile. The ingenuity of the chemist will for ever
remain on record; the phantoms of the physicians have vanished into
air.

Davy was now constantly engaged in the prosecution of new
experiments, in the conception of which, as he himself informs us,
he was greatly aided by the conversation and advice of Dr. Beddoes.
He was also occasionally assisted by Mr. William Clayfield, a
gentleman ardently attached to chemical pursuits, and whose name is
not unknown in the annals of science; indeed, it appears that to
him he was indebted for the invention of a mercurial air-holder,
by which he was enabled to collect and measure the various gases
submitted to examination. He had also the advantages of some
society of a highly intellectual cast: it is sufficient to mention
the names of Edgeworth and James Tobin.

In reply to a letter of enquiry which was lately addressed to her,
Miss Edgeworth observes, that "her father possessed much influence
over Davy's mind;" and that "when he was a very young man at
Clifton, unknown to fame, Mr. Edgeworth early distinguished and
warmly admired his talents, and gave him much counsel, which sunk
deep into his mind."

The present Lord Durham and his brother were also resident in the
house of Dr. Beddoes, not only for their education, but for the
benefit of his professional superintendence. Besides those who
were residing at Clifton, the most distinguished in the circles
of science and literature paid passing visits to Dr. Beddoes;
with many of whom Davy contracted an acquaintance, with some an
intimacy, and with a few a solid and permanent friendship. In
examining the individuals composing this latter class, we find them
differing so widely from each other in character and pursuit, that
we are led to enquire upon what principles of affinity his regards
could possibly have been attracted--the truth is, that there was
more than one avenue to his heart; and the philosopher, the poet,
the physician, the philanthropist, and the sportsman, found each,
upon different terms, a more or less ready access to its recesses.
The chemist who would aspire to his favour, could alone obtain it
by laborious application and novel research; the philanthropist,
by the practicability of his schemes for improving society, and
increasing the sum of its happiness; but the fisherman instantly
caught his affections by a hook and line. To be a fly-fisher
was, in his opinion, to possess the capabilities of intellectual
distinction, although circumstances might not have conspired to
call them into action; whilst a proficiency in this art, when
exhibited by an individual otherwise distinguished, gave him an
additional claim to his attention and regard. The stern courage
of Nelson, tempered as it was with all the kindly feelings of
humanity, was sufficient to excite in the breast of Davy the most
enthusiastic admiration; but the circumstance of his having been
a fly-fisher, and continued the sport, even with his left hand,
threw, in his opinion, a still brighter halo around his character.

No one who knew him can accuse him of inconstancy in his
friendships: amidst the excitements of his station, and the
abstractions incident to his pursuits, he might not always have
shown those little attentions which are received by the world as
the indications of personal regard; but his heart beat not less
warmly on that account: when the flame of affection had been
once kindled, it burnt with a pure and steady light through life.
This will be readily seen in the letters addressed to his several
early friends, more especially to Mr. Poole of Nether Stowey, in
Somersetshire, and to Mr. Clayfield of Bristol, from which I shall
have occasion to present some interesting extracts.

Those who had become acquainted with him in early life, and were
enabled to watch the whole progress of his career from obscurity to
the highest pinnacle of fame, have declared that his extraordinary
talents never at any period excited greater astonishment and
admiration than during his short residence at Bristol. His
simplicity of mind and manner was also at this time truly
delightful. He scarcely knew the names of our best authors, much
less read any of their works; yet upon topics of moral philosophy
and metaphysics he would enter into discussion with acknowledged
scholars, and not only delight them with the native energy of
his mind, but instruct them by the novelty and truth of his
conceptions. Mr. Coleridge lately expressed to me the astonishment
he felt, very shortly after his introduction to him, on hearing him
maintain an argument upon some abstruse subject with a gentleman
equally distinguished for the extent of his erudition, and for the
talent of rendering it available for illustration;--the contrast
was most striking--it was the fresh and native wild flower, opposed
to the elaborate exotic of the _Hortus Siccus_!

During this period he occasionally visited his friend Mr. Gregory
Watt, at Birmingham; at which place his ambition was constantly
excited by intercourse with congenial minds; and his letters to his
mother and relations represent him as rejoicing in the success of
his experiments, and as delighting in his association with kindred
genius; but always casting a longing, lingering thought on the
scenes of his boyhood, he spoke with joyful anticipation of the
period at which he proposed to revisit his mother and family.

That he still continued to regard the practice of physic as the
great end and object of all his pursuits, is evident from one of
these letters, written in 1799, in which he says, "Philosophy,
Chemistry, and Medicine, are my profession."

On the 1st of December 1799 he visited London for the first
time, and remained about a fortnight; the friends with whom he
associated upon this occasion were Coleridge, Southey, Gregory
Watt, Underwood, James and John Tobin, Thomson, and Clayfield; all
of whom vied with each other in their exertions to render his visit
agreeable, conducting him to such persons and places as were deemed
worthy of his notice.

Of all the letters placed at my disposal, those addressed to his
early friend and patron, Mr. Davies Gilbert, are, in my judgment,
the most interesting: it is true, that as specimens of epistolary
style they have but slender pretensions, and are far less pleasing
than those written to Mr. Poole and others, in later life; but let
it be remembered that, as yet, their writer had never enjoyed the
advantages of literary correspondence. For the defects, however,
of style, there is more than sufficient compensation; they speak
from the heart;--they carry with them internal evidence of the
honest simplicity of his mind, and they throw a light upon the
peculiarities of his genius, which without such aid might be less
perfectly understood; above all, they evince an ardour which no
difficulties could repress, and a confidence which no failures
could extinguish. We clearly discern from his first letters, that
he entered upon his career of experiment with an almost chivalrous
feeling, flushed with the consciousness of native strength, and
exulting in the prospect of destined achievements.

I am aware that there are those who still object, with Dr. Sprat,
to the practice of publishing letters which were never intended for
the public eye, and I experience the inconvenience, while I respect
the delicacy, of such an opinion. I confess, on my own part, I have
always considered, with Mr. Mason, that the objections urged by the
learned historian of the Royal Society are wholly untenable. He
talks of "the souls of men thus appearing undressed, or in a habit
too negligent to go abroad in the streets, although they might be
seen by a few in a chamber." But the undress he would condemn,
is the nakedness of Truth--the negligent attire, the simple and
unadorned expression of those natural and significant traits,
whose value incomparably exceeds the premeditated and artificial
exhibitions of mind and manner. "_Nam in ingenio quoque sicut in
agro, quanquam alia diu serantur atque elaborantur, gratiora tamen
quæ sua sponte nascuntur._"[18]

  [18] Dialogus de Oratoribus,--_Tacit._

I cannot but suspect that Dr. Sprat was, upon this occasion, more
anxious to display a metaphor, than to illustrate a truth. I have
often thought a very curious book might be written to show how
greatly, both in physics and in morals, the progress of truth
has been retarded, and the judgment of men warped, by the abuse
of metaphors; the most correct of which can be nothing more than
the image of Truth reflected, as it were, from a mirror, and
consequently liable to all the delusions of our mental optics. The
figure by which Nature was represented as "_abhorring a vacuum_,"
kept us in ignorance of the true theory of the pump for two
thousand years after the discovery of the weight, or gravity, of
the atmosphere;[19] and the unfortunate P. L. Courier positively
owed his conviction to a metaphor in the Judge's charge--"_Un écrìt
plein de poison._"--Well might the defendant exclaim, "_Sauvez-nous
de la Metaphore!_"

  [19] Plutarch, in expressing the opinion of Asclepiades upon this
  subject, represents him as saying, that the external air, _by
  its weight_, opened its way with force into the breast. Seneca
  also was acquainted with the weight and elastic force of the air;
  for he describes the constant effort by which it expands itself
  when it is compressed, and affirms that it has the property of
  condensing itself, and of forcing its way through all obstacles
  that oppose its passage.--Quæst. Nat. lib. v. c. v. and vi.

The first of the letters to which I have alluded appears to have
been written rather more than five weeks after his arrival at
Clifton.


    TO DAVIES GIDDY, ESQ.

    Clifton, November 12, 1798.

    DEAR SIR,

    I have purposely delayed writing until I could communicate to
    you some intelligence of importance concerning the Pneumatic
    Institution. The speedy execution of the plan will, I think,
    interest you, both as a subscriber and a friend to science and
    mankind. The present subscription is, we suppose, nearly adequate
    to the purpose of investigating the medicinal powers of factitious
    airs; it still continues to increase, and we may hope for the
    ability of pursuing the investigation to its full extent. We are
    negotiating for a house in Dowrie Square, the proximity of which to
    Bristol, and its general situation and advantages, render it very
    suitable to the purpose. The funds will, I suppose, enable us to
    provide for eight or ten patients in the hospital, and for as many
    out of it as we can procure.

    We shall try the gases in every possible way. They may be condensed
    by pressure and rarefied by heat. _Quere_,--would not a powerful
    injecting syringe,[20] furnished with two valves, one opening into
    an air-holder and the other into the breathing chamber, answer
    the purpose of compression better than any other apparatus? Can
    you not, from your extensive stores of philosophy, furnish us
    with some hints on this subject? May not the non-respirable gases
    furnish a class of different stimuli? of which the _oxymuriatic
    acid gas_ would stand the highest, if we might judge from its
    effects on the lungs; then, probably, _gaseous oxyd of azote_, and
    _hydro-carbonate_.

    I suppose you have not heard of the discovery of the native
    _sulphate of strontian_ in England. I shall perhaps surprise you by
    stating that we have it in large quantities here. It had long been
    mistaken for _sulphate of barytes_, till our friend Clayfield,
    on endeavouring to procure the _muriate of barytes_ from it by
    decomposition, detected the strontian. We opened a fine vein of it
    about a fortnight ago, at the Old Passage near the mouth of the
    Severn. It was embodied in limestone and gypsum, the outside of
    the vein, a striated mass; the internal parts finely crystallized
    in cubes, of the Sp. Gr. 4·1. Clayfield has been working at it for
    some time. We have persuaded him to publish his analysis in the
    first volume of the Western Physical Collection.

    I have made with him the phosphuret of barytes and of strontian:
    they possess, in common with that of lime, the property of
    producing phosphorized hydrogen gas; the phosphuret of strontian,
    it appears, in a more eminent degree.

    We have likewise attempted to decompose the boracic and muriatic
    acids, by passing phosphorus, in vapour, through muriate, and
    borate of lime, heated red. Phosphate of lime was found in the
    experiment on the boracic acid; but, as no pneumatic apparatus was
    employed, the experiment was uncertain. We shall repeat them next
    week.

    We are printing in Bristol the first volume of the 'West Country
    Collection,' which will, I suppose, be out in the beginning of
    January.

    Mrs. Beddoes hopes that Miss Giddy received her letter, and desires
    me to certify that she wrote almost immediately after the reception
    of her epistle. She is as good, amiable, and elegant as when you
    saw her. Believe me, dear Sir, with affection and respect,

    Truly your's,
    HUMPHRY DAVY.

  [20] Here the reader will recognise the force of early
  associations.


The work announced in the above letter was published in the
commencement of the year 1799, under the title of "Contributions
to Physical and Medical Knowledge, principally from the West of
England; collected by Thomas Beddoes, M.D."

The first two hundred pages, constituting very nearly half the
volume, are the composition of Davy, and consist of essays "On
Heat, Light, and the Combinations of Light." "On Phos-oxygen, or
Oxygen and its Combinations;" and "On the Theory of Respiration."

His first essay commences with an experiment, in order to show that
light is not, as Lavoisier supposed, a modification, or an effect,
of heat, but matter of a peculiar kind, _sui generis_, which, when
moving through space, or in a state of projection, is capable of
becoming the source of a numerous class of our sensations.

A small gunlock was armed with an excellent flint, and, on being
snapped in an exhausted receiver, did not produce any light. The
experiment was repeated in carbonic acid, and with a similar
result. Small particles were in each case separated from the steel,
which, on microscopic examination, evidently appeared to have
undergone fusion. Whence Davy argued, that light cannot be caloric
in a state of projection, or it must have been produced in these
experiments, where heat existed to an extent sufficient to fuse
steel. Nor, that it can be, as some have supposed, a vibration of
the imaginary fluid ether; for, granting the existence of such a
fluid, it must have been present in the receiver. If, then, light
be neither caloric in a state of projection, nor the vibration of
an imaginary ether, it must, he says, be a substance _sui generis_.

With regard to caloric, his opinion that it is not, like light,
material, has been already noticed. In the present essay he
maintains the proposition by the same method of reasoning as that
by which he attempts to establish the materiality of light, and
which mathematicians have termed the "_reductio ad absurdum_."

In his chapter on "Light and its Combinations," he indulges in
speculations of the wildest nature, although it must be confessed
that he has infused an interest into them which might almost be
called dramatic. They are certainly highly characteristic of that
enlightened fancy, which was perpetually on the wing, and whose
flight, when afterwards tempered and directed by judgment, enabled
him to abstract the richest treasures from the recesses of abstract
truth.

Taking it for granted that caloric has no existence as a material
body, or, in other words, that the phenomena of repulsion do not
depend upon the agency of a peculiar fluid, and that, on the
contrary, light is a subtle fluid acting on our organs of vision
_only when in a state of repulsive projection_, he proceeds to
examine the French theory of combustion; the defects of which he
considers to arise from the assumption of the imaginary fluid
_caloric_, and the total neglect of _light_. He conceives that
the light evolved during combustion previously existed in the
oxygen gas, which he therefore proposes for the future to call
PHOS-OXYGEN.[21]

  [21] Brugnatelli considered that oxygen, in certain cases of
  combination, entered into union with different bodies, without
  parting with its _caloric_; and in that state he gave it the
  name of THERM-OXYGEN; so that Davy had a precedent for his
  nomenclatural innovation.

In following up this question, he would seem to consider Light
as the _Anima Mundi_, diffusing through the universe not only
organization, but even animation and perception.

_Phos-oxygen_ he considers as capable of combining with
additional proportions of Light, and of thus becoming '_luminated
Phos-oxygen!_'--from the decomposition of which, and the consequent
liberation of light, he seeks to explain many of the most recondite
phenomena of Nature.

We cannot but admire the eagerness with which he enlists known
facts into his service, and the boldness with which he ranges
the wilds of creation in search of analogies for the support and
illustration of his views. He imagines that the _Phos-oxygen_,
when thus _luminated_, must necessarily have its specific gravity
considerably diminished by the combination, and that it will
therefore occupy the higher regions of the atmosphere; hence, he
says, it is that combustion takes place at the tops of mountains
at a lower temperature than in the plains, and with a greater
liberation of light. The hydrogen which is disengaged from the
surface of the earth, he supposes, will rise until it comes into
contact with this _luminated Phos-oxygen_, when, by its attracting
the oxygen to form water, the light will be set free, and give
origin to the phenomena of fiery meteors at a great altitude.

The phenomenon termed '_Phosphorescence_,' or that luminous
appearance which certain bodies exhibit after exposure to heat, is
attributed by this theory to the light, which may be supposed
to quit such substances as soon as its particles have acquired
repulsive motion by elevation of temperature.

The Electric Fluid is considered as Light in a condensed state,
or, in other words, in that peculiar state in which it is not
supplied with a repulsive motion sufficiently energetic to impart
projection to its particles; for, he observes, that its chemical
action upon bodies is similar to that of Light; and when supplied
with repulsive motion by friction, or by the contact of bodies from
which it is capable of subtracting it, it loses the projectile
form, and becomes perceptible as Light. It is extremely probable,
he adds, that the great quantity of this fluid almost everywhere
diffused over our earth is produced by the condensation of Light,
in consequence of the subtraction of its repulsive motion by black
and dark bodies; while it may again recover the projectile force
by the repulsive motion of the poles, caused by the revolution
of the earth on its axis, and thus appear again in the state of
sensible light; and hence the phenomenon of the _Aurora Borealis_,
or Northern Lights.

In considering the theory of Respiration, he supposes that
_phos-oxygen_ combines with the venous blood without decomposition;
but that, on reaching the brain, the light is liberated in the form
of Electricity, which he believes to be identical with the nervous
fluid. On this supposition, sensations and ideas are nothing more
than motions of the nervous ether; or light exciting the medullary
substance of the nerves and brain into sensitive action!

He thinks it would be worth while to try, by a very sensible
electrometer, whether an insulated muscle, when stimulated into
action, would not give indications of the liberation of electric
fluid, although he suspects that in man the quantity is probably
too small, and too slowly liberated, to be ascertainable. In the
torpedo, and in some other animals, however, it is unquestionably
given out perceptibly during animal action.

When any considerable change takes place in the organic matter
of the body, so as to destroy the powers of life, new chemical
attractions and repulsive motions take place, and the different
principles of which the body is composed enter into new
combinations. In this process, which is called putrefaction, Davy,
in pursuance of this theory, thinks that in land-animals the latent
light of the system enters into new combinations with oxygen and
nitrogen, but that in fish no such combinations occur, and hence
the luminous appearance which accompanies their putrefaction.

Such is the outline of these extraordinary Essays. They stand upon
record, and therefore, as a faithful biographer, I was bound to
notice them; nor are they devoid of interest or instruction: I am
not quite sure that, amidst all the meteors of his fancy, there may
not be a gleam of truth. I allude to his theory of Respiration: it
certainly does not square aôwith the physiological opinions of the
day; nor did that of Newton, when he conjectured that water might
contain an inflammable element; but it was the refraction of a
great truth, at that time below the horizon.

It was a very ancient opinion, that life, being in its own
nature aëriform, is under the necessity of renewing itself by
inspiring the air. Modern chemistry, by teaching us the nature
of the atmosphere, has dispelled many fanciful theories of its
action, but it has not yet explained why respiration, the first
and last act of life,[22] cannot be suspended, even for a minute,
without the extinction of vitality. When we reflect upon this
fact, it is scarcely possible not to believe that the function has
been ordained for some greater purpose than that of removing a
portion of carbon from the circulating blood. Is it unreasonable
to conclude that some principle is thus imparted, which is too
subtle to be long retained in our vessels, and too important to
be dispensed with, even for the shortest period? "I offer this
opinion," as Montaigne says, "not as being good, but as being my
own."

  [22] Breath and life are synonymous. In the Greek, the most
  philosophically constructed language with which we are
  acquainted, this _first_ and _last_ act is expressed by a verb
  composed of alpha and omega--[Greek: aô]. In the Latin, the
  connexion between _spiro_ and _spiritus_, breath and life, is
  evident.

By these observations, I am not to be supposed as wishing, for a
moment, to uphold the wild hypotheses which I have just related; it
must be admitted that the theory of _phos-oxygen_ and _luminated
phos-oxygen_ has scarcely a parallel in extravagance and absurdity;
and I happen to know that, in after life, Davy bitterly regretted
that he had so committed himself; any allusion to the subject became
a source of painful irritation. It is to be remarked, that in every
course of lectures, although Davy did not refer to these theories,
he frequently alluded to the unphilosophic spirit that had given
origin to them; as if he had imposed upon himself this penance
as an atonement for his early follies. The following note
was taken at one of his lectures:--"After what has been said, it
will be useless to enter upon an examination of any of those
theories, which, assuming for their foundation the connexion of life
with respiration, have attempted to prove that oxygen is the
principle of life, and that the wonderful and mysterious
phenomena of perception arise from the action of common gravitating
substances upon each other. Such theories are the dreams of misemployed
genius, which the light of experiment and observation has
never conducted to truth, and are merely a collection of terms
derived from known phenomena, and applied by loose analogies
of language to unknown things."

The reader, however, will be disposed to treat him with all
tenderness when he remembers that the author of these Essays was
barely eighteen years of age. If blame is to fall on any one,
let it fall on Dr. Beddoes, who never should have sanctioned the
publication: had he curbed the ardent and untamed imagination of
the young philosopher, he would have acted the part of a wise
man and of a kind friend. But the truth is, that much as Davy
needed the bridle, Beddoes[23] required it still more; for,
notwithstanding his talents, he was as little fitted for a Mentor
as a weathercock for a compass; and had it not been for the
ascendency which Davy gained over his mind, the ardour of his
temperament would have continually urged him beyond the bounds of
reason.

  [23] The only pun Davy is said to have ever made was upon the
  occasion of Mr. Sadler being appointed by Dr. Beddoes as his
  successor. "I cannot imagine," said he, "why he has engaged
  _Sadler_, unless it is that he may be well _bridled_."

Caught by the loosest analogies, he would arrive at a conclusion
without examining all the conditions of his problem. In the
exercise of his profession, therefore, he was frequently led to
prescribe plans which he felt it necessary to retract the next
hour. His friend Mr. T---- had occasion to consult him upon the
case of his wife: the Doctor prescribed a new remedy; but, in the
course of the day he returned in haste, and begged that, before
Mrs. T---- took the medicine, its effect might be tried on a dog!

The following anecdote, which was lately communicated to me by
Mr. Coleridge, will not only illustrate a trait of character, but
furnish a salutary lesson to the credulous patron of empirics. As
soon as the powers of nitrous oxide were discovered, Dr. Beddoes
at once concluded that it must necessarily be a specific for
paralysis. A patient was selected for the trial, and the management
of it was entrusted to Davy. Previous to the administration of the
gas, he inserted a small pocket thermometer under the tongue of
the patient, as he was accustomed to do upon such occasions, to
ascertain the degree of animal temperature, with a view to future
comparison. The paralytic man, wholly ignorant of the nature of
the process to which he was to submit, but deeply impressed, from
the representations of Dr. Beddoes, with the certainty of its
success, no sooner felt the thermometer between his teeth than
he concluded that the _talisman_ was in full operation, and in
a burst of enthusiasm declared that he already experienced the
effects of its benign influence throughout his whole body:--the
opportunity was too tempting to be lost--Davy cast an intelligent
glance at Mr. Coleridge, and desired the patient to renew his visit
on the following day, when the same ceremony was again performed,
and repeated every succeeding day for a fortnight, the patient
gradually improving during that period, when he was dismissed as
cured, no other application having been used than that of the
thermometer. Dr. Beddoes, from whom the circumstances of the case
had been intentionally concealed, saw in the restoration of the
patient the confirmation of his opinion, and the fulfilment of
his most ardent hope--Nitrous Oxide was a specific remedy for
Paralysis! "It were criminal to retard the general promulgation of
so important a discovery; it were cruel to delay the communication
of the fact until the publication of another volume of his
'_Contributions_;' the periodical magazines were too slow in their
rate of travelling,--a flying pamphlet would be more expeditious;
paragraphs in the newspapers; circulars to the hospitals:"--such
were the reflections and plans which successively agitated the
physician's mind, when his eyes were opened to the unwelcome truth
by Davy's confessing the delusion that had been practised.

A short time after the publication of the first volume of the
"Contributions," Davy addressed to his friend the following
letter:--


    TO DAVIES GIDDY, ESQ.

    Clifton, Feb. 22, 1799.

    DEAR FRIEND,--for I love you too well to call you by a more
    ceremonious name,--I have delayed writing to you from day to day,
    expecting that some of our experiments would produce results worthy
    of communication. Since I received your last very acceptable
    letter, I have been chiefly employed in pursuing the experiments on
    Heat, Light, Respiration, &c. Of these experiments I shall give you
    no account, as you will see them in print. I sent you a copy of my
    Essays last week; if you have not received them, I trust you will
    find them at my mother's, or at Mr. Tonkin's.

    In the same parcel were two small packets, one from Mrs. Beddoes
    for your father, the other for Miss Giddy from Mrs. Willoughby.
    About a fortnight ago I sent a few chemical instruments to Mr.
    Penneck of Penzance; and inclosed with them were specimens of the
    different varieties of sulphate of strontian addressed to you. If
    you have not received them, you will get them by sending to Mr.
    Penneck.

    On looking over a box of minerals last week, which was sent to
    Dr. Beddoes from Cumberland, I found two very fine specimens of
    sulphate of strontian, marked by the collector _Laminated Shorl_. I
    suspect this mineral is not scarce in calcareous countries; it is,
    I dare say, often mistaken for sulphate of barytes.

    I have succeeded in combining strontian with the oxygenated
    muriatic acid. This salt possesses most astonishing properties;[24]
    you will find an account of them in my Essay.

    When you have perused my papers, I shall be very much obliged to
    you for a criticism upon them. When I left Penzance, I was quite an
    infant in speculation,--I knew very little of Light or Heat. I am
    now as much convinced of the non-existence of caloric, as I am of
    the existence of light. Independent of the experiments which appear
    to demonstrate its non-existence directly, and of which you will
    find an account in my Essay, the consideration of certain phenomena
    leads me to suppose that there would be no difficulty in proving
    its non-existence by reasoning. These considerations have occurred
    to me since the publication of the work. I could now render it much
    more perfect; but I hope soon to complete the investigation of the
    combinations of Light, and to produce a much more perfect work on
    the subject. I shall be infinitely obliged to you for any hints
    or observations, as far as the detection of errors of any kind,
    for it is no flattery to say that I pay greater deference to your
    opinion than to that of any other philosopher.

    We intend next week to endeavour to ascertain, by the aid of a
    delicate balance, the quantities of Light liberated in different
    combustive processes. That there is a deficiency of weight, I am
    convinced from many experiments.

    The experiments on Light, &c. have prevented me from attempting
    the decomposition of the undecompounded acids. We have ordered an
    apparatus at the glass-house for this purpose, and I hope next
    week we shall be able to carry on the investigation. Two modes
    of effecting these decompositions have occurred to me:--first,
    to bring phosphorus or sulphur, in the gaseous state, in contact
    with the acid gases in a tube heated intensely; secondly, to send
    sulphur in the gaseous state through muriate of copper or lead,
    heated white. The attraction of sulphur for oxygen, of copper
    for oxygen, and of sulphur for copper, will probably effect the
    decomposition.

    Our laboratory in the Pneumatic Institution is nearly finished, and
    we shall begin the investigations in about a fortnight. We shall
    begin by trying the gases in their simplest mode of application,
    and gradually carry on the more complex processes.

    I hope the gaseous oxide of azote will prove to be a specific
    stimulus for the absorbents.

    I was last week surprised by a letter from Mr. Watt, announcing
    the success of their trial. When I was at Birmingham five weeks
    ago, the family were in very low spirits. I spent nine or ten
    days there, chiefly with Mr. Keir and Mr. Watt: I had a great
    deal of chemical conversation with them. Mr. Keir is one of the
    best-informed men I have ever met with, and extremely agreeable.
    Both he and Mr. Watt are still phlogitians; but Mr. Keir altogether
    disbelieves the doctrine of _calorique_.

    What news have you in Cornwall? Has Mr. John Hawkins returned to
    his native county? he will doubtless be a great acquisition to you.

    Pray do you know whether the Zoophyta and marine worms are
    susceptible of the galvanic stimulus? Experiments on them would
    go far to determine whether the irritable or sensitive fibre is
    primarily affected.

    I know of little general scientific news. In the last volume of the
    _Annales de Chimie_ is a curious paper by Berthollet on sulphurated
    hydrogen: he makes it out to be an acid. I shall most anxiously
    expect a letter from you, and I remain with affection and respect,

    Yours,
    HUMPHRY DAVY.

  [24] The following is the account given in his Essay. "When
  sulphuric acid was poured into a solution of this salt in water,
  a beautiful and unexpected phenomenon took place. The room was
  accidentally darkened at the moment this experiment was made, so
  that we were enabled to perceive a vivid luminous appearance.
  This experiment, independent of its beauty, is extremely pleasing
  as affording an instance of true combustion, that is, the
  production of Light and Heat by the mixture of two incombustible
  bodies." It may be presumed, that this phenomenon arose from the
  developement and decomposition of a portion of Euchlorine, a
  compound which he subsequently discovered in 1811. In the year
  1813, Chevreul announced, as a new discovery, that if strontian
  be heated in contact with muriatic acid gas, the gas is absorbed,
  and the earthy salt becomes red hot.--_See Annals of Philosophy_,
  vol. ii. p. 312.


The letter which follows may be considered as a reply to one
received from Mr. Davies Gilbert, which, it would appear, contained
strictures upon his recently published Essays.


    TO DAVIES GIDDY, ESQ.

    April 10, 1799.

    MY DEAR FRIEND,

    The engagements resulting from the establishment of the Pneumatic
    Institution, and from a course of experiments, to which I have
    been obliged to pay great attention, have prevented me from
    acknowledging to you my obligations for the very great pleasure I
    received from your last excellent letter.

    In experiments on Light and Heat, we have to deal with agents whose
    changes we are unable directly to estimate. The most we can hope
    for is such an arrangement of facts as will account for most of the
    phenomena.

    The supposition of active powers common to all matter, from
    the different modifications of which all the phenomena of its
    changes result, appears to me more reasonable than the assumption
    of certain imaginary fluids alone endowed with active powers,
    and bearing the same relation to common matter, as the vulgar
    philosophy supposes spirit to bear to matter.

    That the particles of bodies must move, or separate from each
    other, when they become expanded, is certain. A repulsive motion of
    the particles is directly the cause of expansion; and when bodies
    are expanded by friction, under circumstances in which there could
    be no heat communicated by bodies in contact, no oxidation and
    no diminution of capacity, I see no difficulty in conceiving the
    repulsive motion generated by the mechanical motion.

    Your excellent and truly philosophic observations will induce me to
    pay greater attention to all my positions. It is only by forming
    theories, and then comparing them with facts, that we can hope to
    discover the true system of nature. I will endeavour very soon to
    give an answer to the remaining part of your excellent letter.

    I have now just room to give you an account of the experiments I
    have lately been engaged in, though they are not much connected
    with light and heat.

    _First._--One of Mr. William Coate's children accidentally
    discovered that two bonnet-canes rubbed together produced a faint
    light. The novelty of this phenomenon induced me to examine it, and
    I found that the canes on collision produced sparks of light, as
    brilliant as those from the flint and steel.

    _Secondly._--On examining the epidermis, I found, when it was taken
    off, that the canes no longer gave light on collision.

    _Thirdly._--The epidermis, subjected to chemical analysis, had all
    the properties of silex.

    _Fourthly._--The similar appearance of the epidermis of reeds,
    corn, and grasses, induced me to suppose that they likewise
    contained silex. By burning them carefully, and analysing their
    ashes, I found that they contained it in rather larger proportions
    than the canes.

    _Fifthly._--The corn and grasses contain sufficient potash to form
    glass with their flint. A very pretty experiment may be made on
    these plants with the blow-pipe. If you take a straw of wheat,
    barley, or hay,[25] and burn it, beginning at the top, and heating
    the ashes with the blue flame, you will obtain a perfect globule of
    hard glass fit for microscopic experiments.

    I made a discovery yesterday which proves how necessary it is
    to repeat experiments. The gaseous oxide of azote is perfectly
    respirable when pure. It is never deleterious but when it contains
    nitrous gas. I have found a mode of obtaining it pure, and I
    breathed to-day, in the presence of Dr. Beddoes and some others,
    sixteen quarts of it for near seven minutes. It appears to support
    life longer than even oxygen gas, and absolutely intoxicated me.
    Pure oxygen gas produced no alteration in my pulse, nor any other
    material effect; whereas this gas raised my pulse upwards of twenty
    strokes, made me dance about the laboratory as a madman, and has
    kept my spirits in a glow ever since. Is not this a proof of the
    truth of my theory of respiration? for this gas contains more light
    in proportion to its oxygen than any other, and I hope will prove a
    most valuable medicine.

    We have upwards of eighty out-patients in the Pneumatic
    Institution, and are going on wonderfully well.

    I shall hope for the favour of a letter from you, and in my answer
    to it will fully inform you of our proceedings. I have just room to
    add that I am

    Yours, with affection and respect,
    HUMPHRY DAVY.

  [25] It is very common, after the burning of a hay-stack, to find
  glass in the ashes. P.


I cannot suffer the experiments with the bonnet-canes to pass,
without endeavouring to infuse into the reader a portion of that
admiration which I feel in relating them. They furnish a beautiful
illustration of that combination of observation, experiment, and
analogy, first recommended by Lord Bacon, and so strictly adopted
by Davy in all his future grand researches.

In alluding to this discovery--that siliceous earth exists
generally in the epidermis of hollow plants--Davy observes in his
agricultural lectures, that "the siliceous epidermis serves as a
support, protects the bark from the action of insects, and seems
to perform a part in the economy of these feeble vegetable tribes,
similar to that performed in the animal kingdom by the shell of the
crustaceous insects."

The circumstance that first led him to the investigation of the
nature of _nitrous oxide_, or the _gaseous oxide of azote_, alluded
to in the foregoing letter, has been thus recorded by himself. "A
short time after I began the study of Chemistry, in March 1798, my
attention was directed to the _dephlogisticated nitrous gas_ of
Priestley (nitrous oxide) by Dr. Mitchell's theory of Contagion, by
which he attempted to prove that _dephlogisticated nitrous gas_!
which he calls _oxide of septon_, was the principle of contagion,
and capable of producing the most terrible effects, when respired
by animals in the minutest quantities, or even when applied to the
skin, or muscular fibre.

"The fallacy of this theory was soon demonstrated by a few coarse
experiments, made on small quantities of this gas procured, in the
first instance, from zinc and diluted nitrous acid. Wounds were
exposed to its action; the bodies of animals were immersed in it
without injury; and I breathed it, mingled in small quantities
with common air, without any remarkable effects. An inability to
procure it in sufficient quantities prevented me, at this time,
from pursuing the experiments to any greater extent. I communicated
an account of them to Dr. Beddoes."

His situation in the "Medical Pneumatic Institution" in 1799,
imposing upon him the duty of investigating the physiological
effects of such aëriform fluids as held out any promise of useful
agency, he resumed the investigation; a considerable period,
however, elapsed, before he succeeded in procuring _nitrous oxide_
in a state of purity; he was therefore obliged to breathe it in
mixture with oxygen gas, or common air; but as no just conclusion
could be deduced from the action of an impure gas, he commenced an
enquiry for the purpose of discovering a process by which it might
be procured in an uncontaminated condition; when, after a most
laborious investigation concerning its composition, properties,
and combinations, enquiries which were necessarily extended to the
different bodies connected with nitrous oxide, such as _nitrous
gas_, _nitrous acid_, and _ammonia_, he was enabled, by a series
of intermediate and comparative experiments, to reconcile apparent
anomalies, and thus, by removing the greater number of those
difficulties which had previously obscured this branch of science,
to present to the chemical world the first satisfactory history of
the COMBINATIONS OF OXYGEN AND NITROGEN.

Thus prepared, he proceeded to examine the action of nitrous oxide
upon living beings, and to compare it with the effects of other
gases upon man; and in this manner he completed its physiological,
as he had already done its chemical history.

These interesting results were published in a distinct volume, in
the year 1800, entitled, "Researches Chemical and Philosophical,
chiefly concerning Nitrous Oxide, and its Respiration. By Humphry
Davy, Superintendent of the Medical Institution."

It may be observed in passing, that the merits of this work could
never have been inferred from the title-page, which its most
sanguine admirers must admit to be as clumsy and unpromising an
invitation as an author ever addressed to his scientific brethren.

Amongst Davy's letters to Mr. Gilbert, I find one written on a
proof sheet of the chapter of contents of the above work, and which
may not be uninteresting in this place.


    TO DAVIES GIDDY, ESQ.

    July 3, 1800.

    That our feelings, as well as our actions, are rendered stronger
    and more vivid by habit, is probable from many facts, and from no
    one more so than that of procrastination. My much respected friend,
    two months after my return,[26] I had formed the resolution of
    writing to you; week after week this resolution was renewed and put
    off to a future day, with the hope that this day, by presenting
    something new, would enable me to make my letter more interesting.
    In vain! the feeling of procrastination, thus increased by
    association, at length became so strong as to prevent me from
    writing at all.[27]

    I have received your letter; it has awakened my duties, and has
    been doubly welcome, as being unexpected and undeserved.

    Since my return to the Pneumatic Institution in December, I have
    been almost incessantly occupied, from January to April, in
    completing a series of experiments on Gases, and their application;
    and from April to the present time, in writing and printing an
    account of them.

    I have written this letter on the table of contents of a work which
    will be published in the course of the month, and of which I shall
    take the earliest opportunity to send you a copy. This table of
    contents will give you a better idea of the nature and extent of
    the investigation, than I could possibly have given in a letter.

    We have been repeating the Galvanic experiments with success.
    Nicholson, by means of a hundred pieces of silver and zinc, has
    procured a visible spark. Cruickshank has revived oxidated metals
    in solution, by means of the nascent hydrogen produced from the
    decomposition of water by the shock; and both he and Carlisle have
    absolutely resolved water into oxygen and hydrogen by means of
    it, making use of silver and platina wires. An immense field of
    investigation seems opened by this discovery: may it be pursued so
    as to acquaint us with some of the laws of life!

    You have, undoubtedly, heard of Herschel's discovery concerning
    the production of heat by invisible rays emitted from the sun. By
    placing one thermometer within the red rays, separated by a prism,
    and another beyond them, he found the temperature of the outside
    thermometer raised more than that of the inside one.

    When I first heard of Mr. Tennant's discovery,[28] I was very much
    struck by an observation which you long ago made to me, on the
    fertility of the Cornish lands, in which there was decomposed,
    _feltspar_ or _serpentine_.

    Mr. Tennant spent a day here some time ago, when I mentioned
    your observation to him, but he could not give any solution of
    the phenomenon. _Quere._--As lime and magnesia are probably both
    subservient to vegetation, only from supplying plants with carbonic
    acid, may not lime, when mingled with magnesia, in the process of
    vegetation, render it partially caustic, and thus enable it to
    destroy them?

    Your observation on the scale of numbers, and the fact relative
    to it, are highly interesting. Reasoning on this subject would
    literally form the logic of generalization, or the application of
    one term to signify many terms, or many ideas, on which science
    ultimately depends. _Quere._--How far have the first attempts
    at generalization arisen from accident, and how far from the
    resemblance between ideas?

    Dr. Beddoes has always ridiculed the "_Tractors_," in common with
    all other reasonable men. He is about to publish a new work on the
    Nitrous Acid.

    J. Wedgwood is returned, very little altered for the better.
    Coleridge is gone to reside in Cumberland; he was here the week
    before last, and spent much time with me, and often spoke of you
    with the greatest interest. Clayfield is at this moment chiefly
    engaged in commercial speculations. He has found a new mode of
    making soda, which there is every reason to believe will turn out
    profitable.

    I hope some time in the autumn to see you, and to enjoy the well
    remembered pleasure of your conversation; in the mean while, I
    remain, with respects to your family,

    Yours with sincere affection,
    HUMPHRY DAVY.

  [26] From his visit to London, as noticed at page 62.

  [27] With respect to the metaphysical speculation contained in
  this paragraph of his letter, had he not written it in haste, we
  might presume he would have given a more exact expression to his
  ideas. By the misapplied term "_Feeling of Procrastination_," he
  doubtless meant to describe that aversion to labour which becomes
  habit by indulgence, and the perception of which, so far from
  increasing in vividness, actually languishes to obtuseness. To
  borrow an expression from Dr. Johnson, Davy, in his metaphysical
  speculations, not unfrequently trod upon the brink of meaning,
  where light and darkness begin to mingle.

  [28] Davy here alludes to the fact of magnesian earth being
  prejudicial to vegetation.


In estimating the early genius of Davy, and his character as a
philosopher, the style and matter of his "RESEARCHES" will afford
us much assistance. The close philosophical reasoning,--the
patient and penetrating industry,--the candid submission to every
intimation of experiment, and the accuracy of manipulation, so
remarkably displayed throughout this work, have been rarely
equalled, and perhaps never surpassed.

There is scarcely to be found a more striking illustration
of chemical genius, than that afforded by his chapter on the
"Absorption of _Nitrous Gas by solutions of green Sulphate of
Iron_."

The address with which he gradually disentangles the subject of
its difficulties, and catches at every opening to truth, affords
a study which may be safely recommended to the attention of every
young experimentalist, as being no less instructive than it is
beautiful.

The phenomena attending the absorption of _nitrous gas_ by
solutions of _sulphate of iron_ had been examined by Vauquelin and
by Berthollet, but the conclusions of these chemical philosophers
were fatally infected by errors, arising from the neglected action
of the atmosphere. Davy, by conducting his experiments over
mercury, proved that, in the absence of air, the absorption was
simply owing to a combination between the gas and the fluid; but
that, on admitting air, the nitrous _gas_ became nitrous _acid_, a
portion of which, together with a part of the water, subsequently
underwent decomposition, and gave origin to _ammonia_, and
ultimately to _nitrate of ammonia_, while the iron passed into the
state of a _peroxide_.

We have also to admire in this work an ardour for investigation,
which even the most imminent personal danger could not repress. He
may truly be said to have sought the bubble reputation in the very
jaws of Death. What shall we say of that spirit which led him to
inspire nitrous gas, at the hazard of filling his lungs with the
vapour of _aqua fortis_! or what, of that intrepid coolness which
enabled him to breathe a deadly gas, and to watch the advances of
its chilling power in the ebbing pulsations at the wrist!

These experiments, however, are far too interesting and important
to be related in any other than the author's own words; but it is
first necessary that his trials with the _nitrous oxide_ should be
considered.

He found that this gas might be most conveniently, as well as most
economically, prepared by the decomposition of a salt known by the
name of _nitrate of ammonia_, by the application of a regulated
heat; but, as the researches by which he arrived at this conclusion
are recorded at length in his work, and as the most important of
them are now embodied in every elementary system of chemistry, it
would not only be tedious but useless, to enter into a detail of
them upon this occasion.

"In April," he says, "I obtained nitrous oxide in a state
of purity, and ascertained many of its chemical properties.
Reflections upon these properties, and upon former trials, made me
resolve to inspire it in its pure form, for I saw no other way in
which its respirability, or powers, could be determined.

"I was aware of the danger of the experiment. It certainly would
never have been made, if the hypothesis of Dr. Mitchell had in
the least influenced my mind. I thought that the effects might,
possibly, be depressing and painful; but there were many reasons
which induced me to believe, that a single inspiration of a gas,
apparently possessing no immediate action on the irritable fibre,
could neither destroy, nor materially injure, the powers of life.

"On April 11th, I made the first inspiration of pure nitrous oxide.
It passed through the bronchiæ without stimulating the glottis, and
produced no uneasy sensations in the lungs.

"The result of this experiment proved that the gas was respirable,
and induced me to believe that a farther trial of its effects might
be made without danger.

"On April 16th, Dr. Kinglake being accidentally present, I breathed
three quarts of nitrous oxide from and into a silk bag, for
more than half a minute, without previously closing my nose, or
exhausting my lungs. The first inspirations occasioned a slight
degree of giddiness, which was succeeded by an uncommon sense of
fulness in the head, accompanied with loss of distinct sensation
and voluntary power,--a feeling analogous to that produced in
the first stage of intoxication; but unattended by pleasurable
sensation. Dr. Kinglake, who felt my pulse, informed me that it was
rendered quicker and fuller.

"This trial did not satisfy me with regard to its powers: comparing
it with the former ones, I was unable to determine whether the
operation was stimulant or depressing.

"I communicated the result to Dr. Beddoes, and on April the 17th,
he was present when the following experiment was made.

"Having previously closed my nostrils, and exhausted my lungs, I
breathed four quarts of the gas from and into a silk bag. The first
feelings were similar to those produced in the last experiment;
but in less than half a minute, the respiration being continued,
they diminished gradually, and were succeeded by a sensation
analogous to gentle pressure on all the muscles, attended by an
highly pleasurable thrilling, particularly in the chest and in the
extremities. The objects around me became dazzling, and my hearing
more acute. Towards the last inspirations, the thrilling increased,
the sense of muscular power became greater, and, at last, an
irresistible propensity to action was indulged in: I recollect but
indistinctly what followed; I know that my motions were various and
violent.

"These effects very soon ceased after the respiration of the
gas. In ten minutes I had recovered my natural state of mind.
The thrilling in the extremities continued longer than the other
sensations.

"This experiment was made in the morning; no languor or exhaustion
was consequent; my feelings throughout the day were as usual, and I
passed the night in undisturbed repose.

"The next morning the recollection of the effects of the gas was
very indistinct; and had not remarks written immediately after the
experiment recalled them to my mind, I should even have questioned
their reality."

Our philosopher very naturally doubted whether some of these strong
emotions might not, after all, be attributed to the enthusiasm
necessarily connected with the perception of agreeable feelings,
when he was prepared to expect painful sensations; but he says,
that subsequent experiments convinced him that the effects were
solely owing to the specific operation of the gas. He found that
he could breathe nine quarts of nitrous oxide for three minutes,
and twelve quarts for rather more than four; but that he could
never breathe it, in any quantity, so long as five minutes.
Whenever its operation was carried to the highest extent, the
pleasurable thrilling, at its height about the middle of the
experiment, gradually diminished, the sense of pressure on the
muscles was lost, impressions ceased to be perceived, vivid ideas
passed rapidly through the mind, and voluntary power was altogether
destroyed, so that the mouthpiece generally dropped from his
unclosed lips. When he breathed from six to seven quarts, muscular
motions were produced to a great extent: sometimes he manifested
his pleasure by stamping, or laughing only; at other times, by
dancing round the room, and vociferating.

During the progress of these experiments, it occurred to him that,
supposing _nitrous oxide_ to be analogous in its operation to
common stimulants, the debility occasioned by intoxication from
fermented liquors ought to be increased after excitement from this
gas, in the same manner as the debility produced by two bottles of
wine is increased by a third. To ascertain whether this was the
case, he drank a bottle of wine, in large draughts, in less than
eight minutes. His usual drink, he tells us, was water; he had
been little accustomed to take spirits or wine, and had never been
intoxicated but once before in the course of his life. Under such
circumstances, we may readily account for the powerful effects
produced by this quantity of wine, and which he describes in the
following manner:--

"Whilst I was drinking, I perceived a sense of fulness in the
head, and throbbing of the arteries, not unlike that produced in
the first stage of nitrous oxide excitement: after I had finished
the bottle, this fulness increased, the objects around me became
dazzling, the power of distinct articulation was lost, and I was
unable to stand steadily. At this moment, the sensations were
rather pleasurable than otherwise; the sense of fulness in the
head, however, soon increased, so as to become painful, and in
less than an hour I sunk into a state of insensibility. In this
situation I must have remained for two hours, or two hours and a
half. I was awakened by head-ache and painful nausea. My bodily and
mental debility were excessive, and the pulse feeble and quick.

"In this state, I breathed for near a minute and a half five quarts
of gas, which was brought to me by the operator for nitrous oxide;
but as it produced no sensations whatever, and apparently rather
increased my debility, I am almost convinced that it was, from some
accident, either common air, or very impure nitrous oxide.

"Immediately after this trial, I respired twelve quarts of oxygen
for nearly four minutes. It produced no alteration in my sensations
at the time, but immediately afterwards I imagined that I was a
little exhilarated.

"The head-ache and debility still, however, continuing with
violence, I examined some nitrous oxide which had been prepared
in the morning, and finding it very pure, I respired seven quarts
of it for two minutes and a half. I was unconscious of head-ache
after the third inspiration; the usual pleasurable thrilling
was produced, voluntary power was destroyed, and vivid ideas
rapidly passed through my mind; I made strides across the room,
and continued for some minutes much exhilarated; but languor and
depression, not very different in degree from those existing
before the experiment, succeeded; they however gradually went off
before bed-time.

"This experiment proved, that debility from intoxication was not
increased by excitement from nitrous oxide. The head-ache and
depression would probably have continued longer, had it not been
administered."

The same work contains an account of many other trials; but
sufficient has been extracted to show the zeal and intrepidity
with which he conducted his researches. To withhold, however, the
testimony which several other scientific persons have given, with
respect to the intoxicating influence of this gas, would be to
deprive the reader of some very amusing descriptions.

First appears Mr. W. Tobin, who tells us that he soon found his
nervous system agitated by the highest sensations of pleasure,
but which were difficult of description. When the bags were
exhausted and taken from him, he suddenly started from his chair,
and vociferating with pleasure, made towards those that were
present, as he wished they should participate in his feelings. He
struck gently at Davy, and a stranger entering the room at the
same moment, he made towards him, and gave him several blows,
but he adds, it was more in the spirit of good-humour, than in
that of anger. He then ran through different rooms in the house,
and at last returned to the laboratory, somewhat more composed,
although his spirits continued much elevated for some hours after
the experiment; he felt, however, no consequent depression,
either in the evening or day following. Upon another occasion,
he states that his sensations were superior to any thing he ever
before experienced; his step was firm, and all his muscular
power increased. His nerves were more alive to every surrounding
impression; he threw himself into several theatrical attitudes,
and traversed the laboratory with a quick step, while his mind was
elevated to a most sublime height: he says that "it is giving but
a faint idea of his feelings to say, that they resembled those
produced by a representation of an heroic scene on the stage, or by
reading a sublime passage in poetry, when circumstances contribute
to awaken the finest sympathies of the soul." The influence,
however, of this inspiring agent appears to have been as transitory
as its effects were vivid; for he afterwards observes, "I have
seldom lately experienced vivid sensations. The pleasure produced
by the gas is slight and tranquil, and I rarely feel sublime
emotions, or increased muscular power."

The first time that Mr. Clayfield breathed the gas, it produced
feelings analogous to those of intoxication. He was for some time
unconscious of existence, but at no period of the experiment
were his sensations agreeable; a momentary nausea followed, but
unconnected with languor or head-ache.

In a subsequent trial, it would appear that he did experience
certain thrillings which were highly pleasurable.

The account given by Dr. Kinglake agrees pretty much with those
already cited. He adds, however, that the inspiration of the gas
had the further effect of reviving rheumatic irritations in the
shoulder and knee-joints, which had not been previously felt for
many months.

Next appears Mr. Southey, the Laureate. The reader will no doubt be
prepared to hear that the nitrous oxide transported him, at least,
to the summit of Parnassus;--by no means: he laughed when the bag
was removed from his mouth, but it may be fairly questioned whether
this might not have been an expression of joy at the terrors he
had escaped; for he freely confesses that he could not distinguish
between the first feelings it occasioned, and an apprehension of
which he was unable to divest himself.

The first time Mr. Coleridge inspired the nitrous oxide, he felt
a highly pleasurable sensation of warmth over his whole frame: he
adds, that the only motion which he felt inclined to make, was
that of laughing at those who were looking at him: a symptom as
equivocal, perhaps, as that exhibited by the Laureate.

A number of other accounts are given, but those already related are
perhaps sufficient to establish the fact, that the gas in question
possesses an intoxicating quality, to which the enthusiasm of
persons submitting to its operation has imparted a character of
extravagance wholly inconsistent with truth.

It will be admitted that there must have been something singularly
ludicrous in the whole exhibition. Imagine a party of grave
philosophers, with bags of silk tied to their mouths, stamping,
roaring, and laughing about the apartment; it is scarcely possible
to conceive a richer subject for the pencil of a Bunbury. We cannot
then be surprised at any terms of ridicule in which a stranger,
witnessing such an operation, might describe it. M. T. Fievée[29]
appears to have considered the practice as a national vice, and
whimsically introduces it amongst the catalogue of follies to which
he considers the English nation to be addicted.

  [29] Lettres sur l'Angleterre, 1802.

Taking leave of these laughing philosophers, we must now proceed to
a much more serious branch of the subject of Pneumatic Medicine.
"Having observed," says Davy, "that no painful effects were
produced by the application of nitrous gas to the bare muscular
fibre, I began to imagine that this gas might also be breathed with
impunity, provided it were possible in any way to free the lungs of
common air before inspiration, so as to prevent the formation of
nitrous acid.

"On this supposition, during a fit of enthusiasm produced by the
respiration of nitrous oxide, I resolved to endeavour to breathe
nitrous gas: one hundred and fourteen cubic inches of it were
accordingly introduced into the large mercurial air-holder; two
small silk bags of the capacity of seven quarts were filled with
nitrous oxide.

"After a forced exhaustion of my lungs, my nose being accurately
closed, I made three inspirations and expirations of nitrous oxide
in one of the bags, in order to free my lungs, as much as possible,
from atmospheric oxygen; then, after a full expiration of the
nitrous oxide, I transferred my lips from the mouthpiece of the bag
to that of the air-holder, and, turning the stop-cock, attempted to
inspire the nitrous gas. In passing through my mouth and fauces,
it tasted astringent and highly disagreeable; it occasioned a sense
of burning in the throat, and produced a spasm of the epiglottis,
so painful as to oblige me to desist immediately from attempts to
inspire it. After removing my lips from the mouthpiece, when I
opened them to inspire common air, _nitrous acid_ was immediately
formed in my mouth, which burnt the tongue and palate, injured the
teeth, and produced an inflammation of the mucous membrane, which
lasted for some hours.

"As, after the respiration of nitrous oxide, a small portion of the
residual atmospheric air always remained in the lungs mingled with
the gas, so is it probable that, in the experiment just related, a
minute portion of nitrous acid was formed; and, if so, I perhaps
owe the preservation of my life to the circumstance; for, supposing
that I had succeeded in taking a full inspiration of nitrous
gas, and even that it had not produced any positive effects, it
is not likely that I should, by breathing nitrous oxide, have
so completely freed my lungs from it, as to have prevented the
formation of nitrous acid, when I again inspired common air. I
never design again to attempt so rash an experiment."

His attempt to breathe carburetted hydrogen gas was scarcely less
terrific and appalling.

"Mr. Watt's observations on the respiration of diluted
_hydro-carbonate_ by man, and the experiments of Dr. Beddoes on the
destruction of animals by the same gas, proved that its effects
were highly deleterious.

"As it destroyed life, apparently by rendering the muscular fibre
inirritable, without producing any previous excitement, I was
anxious to compare its sensible effects with those of nitrous
oxide, which at this time I believed to destroy life by producing
the highest possible excitement.

"In the first experiment, I breathed for nearly a minute three
quarts of _hydro-carbonate_, mingled with nearly two quarts of
atmospheric air.[30] It produced a slight giddiness, pain in
the head, and a momentary loss of voluntary power; my pulse was
rendered much quicker and more feeble. These effects, however, went
off in five minutes, and I had no return of giddiness.

  [30] "I believe it had never been breathed before by any
  individual in a state so little diluted."

"Emboldened by this trial, I introduced into a silk bag four
quarts of gas nearly pure, which was carefully produced from the
decomposition of water by charcoal an hour before, and which had a
very strong and disagreeable smell.

"My friend Mr. James Tobin, junior, being present, after a forced
exhaustion of my lungs, the nose being accurately closed, I made
three inspirations and expirations of the hydro-carbonate. The
first inspiration produced a sort of numbness and loss of feeling
in the chest, and about the pectoral muscles. After the second, I
lost all power of perceiving external things, and had no distinct
sensation, except that of a terrible oppression on the chest.
During the third expiration, this feeling subsided, I seemed
sinking into annihilation, and had just power enough to cast off
the mouthpiece from my unclosed lips.

"A short interval must have passed, during which I respired
common air, before the objects around me were distinguishable.
On recollecting myself, I faintly articulated, '_I do not think
I shall die._' Placing my finger on the wrist, I found my pulse
thread-like, and beating with excessive quickness. In less than a
minute, I was able to walk, and the painful oppression on the chest
directed me to the open air.

"After making a few steps, which carried me to the garden, my
head became giddy, my knees trembled, and I had just sufficient
voluntary power to throw myself on the grass. Here the painful
feelings of the chest increased with such violence as to threaten
suffocation. At this moment I asked for some nitrous oxide. Mr.
Dwyer brought me a mixture of that gas with oxygen, and I breathed
it for a minute, and believed myself recovered.

"In five minutes the painful feelings began gradually to diminish;
in an hour they had nearly disappeared, and I felt only excessive
weakness, and a slight swimming of the head. My voice was very
feeble and indistinct.

"I afterwards walked slowly for half an hour with Mr. Tobin, and on
my return was so much stronger and better as to believe that the
effects of the gas had entirely passed off; though my pulse was
120, and very feeble. I continued without pain for nearly three
quarters of an hour, when the giddiness returned with such violence
as to oblige me to lie on the bed; it was accompanied with nausea,
loss of memory, and deficient sensation.

"In about an hour and a half, the giddiness went off, and was
succeeded by an excruciating pain in the forehead, and between the
eyes, with transient pains in the chest and extremities.

"Towards night these affections gradually diminished; and at ten no
disagreeable feeling, except weakness, remained. I slept sound, and
awoke in the morning very feeble and very hungry. No recurrence of
the symptoms took place, and I had nearly recovered my strength by
the evening.

"I have been minute in the account of this experiment, because
it proves, that _hydro-carbonate_ acts as a sedative; that is,
it produces diminution of vital action, and consequent debility,
without previously exciting. There is every reason to believe that,
had I taken four or five inspirations, instead of three, they would
have destroyed life immediately, without producing any painful
sensation."

The scientific and medical world are alike indebted to Davy for
this daring experiment; and, if the precautions it suggests be
properly attended to, it may become the means of preserving
human life. The experiment is also valuable as affording support
to physiological views, with which its author was probably not
acquainted.

In the first place, it may be necessary to apprize some of my
readers, that the "_hydro-carbonate_" here spoken of, differs
very little from the gas now so generally used to illuminate our
streets and houses. We have just seen how deadly are its qualities,
and that even in a state of extreme dilution it will affect our
sensations. The question then necessarily suggests itself, how
far this gas can be safely introduced into the interior of our
apartments? Did we not possess any direct evidence upon the
subject, the answer would be sufficiently obvious, since it is
impossible so to conduct its combustion, that a portion shall not
escape unburnt. Such is the theory; but what is our experience
upon the subject?--that pains in the head, nausea, and distressing
languor, have been repeatedly experienced in our theatres and
saloons, by persons inhaling the unburnt gas; that the atmosphere
of a room, although spacious and empty, will, if lighted with gas,
convey a sense of oppression to our organs of respiration, as if
we were inhaling an air contaminated with the breath of a hundred
persons.

In the next place, Davy's experiment is important, inasmuch as it
proves that, in cases of asphyxia, or suspended animation, there
exists a period of danger after the respiration has been restored,
and the circulation re-established, at which death may take place,
when we are the least prepared to expect it.

Bichat has shown that, when dark-coloured blood is injected into
the vessels of the brain by means of a syringe connected with the
carotid artery, the functions of the brain become immediately
disturbed, and in a short time entirely cease: the effect is
precisely similar, whether the dark-coloured blood be transmitted
to the brain by the syringe of the experimentalist, or by the heart
itself. Thus in cases of asphyxia, the dark-coloured blood which
has been propelled through the vessels during the suspension or
imperfect performance of respiration, acts like a narcotic poison
upon the brain; and no sooner, therefore, does it extend its malign
influence to that organ, than deleterious effects are produced,
and the animal, after apparent recovery, falls into a state of
stupor, the pupils of the eyes become dilated, the respiration
laborious, the muscles of the body convulsed, and it speedily dies,
_poisoned by its own blood_.

We are much indebted to Mr. Brodie for a series of experiments in
confirmation of these views; and a very interesting case occurred
some time since, in the neighbourhood of Windsor, which is well
calculated for their illustration. A corporal in the Guards, whose
name, if I am not mistaken, was Schofield, was seized with cramp
as he was bathing in the Thames, and remained for several minutes
under water. By judicious assistance, however, he was recovered,
and appeared to those about him to be free from any danger, when he
was attacked by convulsions and expired. Had the respiration been
artificially supported at this period, so as to have maintained the
action of the heart until the black blood had returned from the
brain, the life of the soldier might possibly have been saved.

In the experiment which has given origin to these reflections, Davy
distinctly states, that after having recovered from the _primary_
effects of the carburetted hydrogen gas, and taken a walk with
his friend Mr. Tobin, he was again seized with violent giddiness,
attended with nausea and loss of sensation. The imperfectly
oxygenized or dark-coloured blood had evidently affected the brain,
and his life, at this period, was probably in greater jeopardy than
in any other stage of the experiment.

Nothing daunted by the dangers to which the preceding experiments
had exposed him, Davy did not allow more than a week to elapse
before he attempted to respire _fixed air_, or _carbonic acid gas_;
but it was in vain that he made voluntary efforts to draw it into
the windpipe; for, the moment the epiglottis was raised a little,
such a painful irritation was induced as instantly to close it
spasmodically on the glottis; and thus, in repeated trials, was he
prevented from taking a single particle of carbonic acid into the
lungs. When, however, the gas was diluted with a little more than
double its volume of common air, he was enabled to breathe it for
nearly a minute, when it produced a slight degree of giddiness, and
an inclination to sleep.[31]

  [31] It would thus appear that carbonic acid, in its most
  concentrated form, may kill by exciting a spasmodic action,
  in which the epiglottis is closed, and the entrance of air
  into the lungs altogether prevented. In a diluted form, it may
  destroy by its specific influence upon the blood, which would
  seem to be of a highly sedative character. Death produced by
  such an agent is probably attended with little or no suffering.
  The younger Berthollet destroyed his life by inclosing himself
  in an atmosphere of this description; and on commencing his
  fatal experiment, he registered all the successive feelings he
  experienced, which were such as would have been occasioned by a
  narcotic:--a pause, and then an almost illegible word occurred:
  it is presumed that the pen dropped from his hand,--and he was no
  more.

It may perhaps appear extraordinary to the reader of the
"RESEARCHES," that although they were published not more than
eighteen months after the appearance of his "Essays on Heat and
Light," no allusion is made in them either to his theory or to his
new nomenclature. In relating his experiments upon Respiration,
he employs the conventional language of the schools, and the
word "_phos-oxygen_" does not once occur in the volume. This is
fully explained in a communication made by him to Mr. Nicholson,
and which was printed in his Journal a short time after the
publication of his Essays in the West Country Contributions; in
which he says,--"As facts have occurred to me with regard to
the decomposition of bodies, which I had supposed to contain
light, without any luminous appearance, I beg to be considered
as a _sceptic_ with respect _to my own_ particular theory of
the combinations of light, until I shall have satisfactorily
explained those anomalies by fresh experiments. On account of this
scepticism, and for other reasons, I shall in future use the common
nomenclature; excepting that, as my discoveries concerning the
gaseous oxide would render it highly improper to call a principle,
which in one of its combinations is capable of being absorbed by
venous blood, and of increasing the powers of life, _azote_,--I
shall name it, with Dr. Pearson, Chaptal, and others, NITROGENE;
and the _gaseous oxide of azote_ I shall call NITROUS OXIDE."

The same feeling is expressed at the conclusion of his Third
Research.--"It would be easy to form theories referring the
action of blood impregnated with _nitrous oxide_, to its power of
supplying the nervous and muscular fibre with such proportions of
condensed nitrogen, oxygen, light, or ethereal fluid, as enabled
them more rapidly to pass through those changes which constitute
their life; but we are unacquainted with the composition of dead
organized matter; and new instruments of experiment, and new
modes of research, must be found, before we can ascertain even our
capabilities of discovering the laws of life."

There is one circumstance connected with the views entertained
in this work which must not be passed over without notice. In
several passages he advocates the theory of the atmosphere being
a _chemical compound_ of oxygen and nitrogen; whereas, in later
years, he was amongst the first to insist upon its being simply a
mechanical mixture of these gases.

In consequence of the highly deleterious experiments which have
been already described, and of the constant labours of the
laboratory, and the repeated inhalation of acid and other vapours,
his health began visibly to decline, and he retired into Cornwall,
where he informs us that "the associations of ideas and feelings,
common exercise, a pure atmosphere, luxurious diet, and a moderate
indulgence in wine, in the course of a month, restored him to
health and vigour."

I find an allusion to this visit in a letter from his sister. "He
had," she says, "written to his mother of his intention to visit
her, but before the post had quitted Bristol, he was already on
his way to Penzance, and would have reached it before his letter,
had not his aunt, on whom he called in the neighbouring town of
Marazion, struck with his appearance of ill health, insisted on his
remaining there till the next day, lest his mother should be doubly
alarmed at his unexpected visit and altered looks." Miss Davy adds,
"This one fact will serve, at the same time, to illustrate his
attachment to home, and the impetuosity of his mind, which never
rested till the object he proposed was accomplished."

The following letter is inserted in this place, for the purpose
of fixing the period at which he first ascertained those new
facts in Voltaic electricity, which formed the basis of a future
communication to the Royal Society, and which may be said to
have paved the way to his grand discoveries in that branch of
science;--the dawning of that glorious day, which we shall
presently view in all its splendour and glory.

There is, moreover, something extremely interesting in receiving
from himself a simple and unadorned statement of results, as they
successively presented themselves to his observation--"Truths
plucked as they are growing, and delivered to you before their dew
is brushed off."


    TO DAVIES GIDDY, ESQ.

    Pneumatic Institution, October 20, 1800.

    Be assured, my respected friend, that your last letter, though
    short, was highly gratifying to me. At the moment it was brought
    to me, I was about to depart with King and Danvers on an excursion
    to the banks of the Wye. Our design was to see Tintern Abbey by
    moonlight, and it was perfectly accomplished.

    After viewing for three hours all the varieties of light and
    shade which a bright full moon and a blue sky could exhibit in
    this beautiful ruin, and after wandering for three days among
    the many-coloured woods and rocks surrounding the river between
    Monmouth and Chepstow, we arrived on the fourth day at Bristol,
    having to balance against the pleasure of the tour, the fatigue of
    a stormy voyage down the Wye, across the mouth of the Severn, and
    up the Avon.

    On analysing, after our return, specimens of the air collected from
    Monmouth, from the woods on the banks of the Wye, and from the
    mouth of the Severn, there was no perceptible difference; they were
    all of similar composition to the air in the middle of Bristol;
    that is, they contained about twenty-two per cent. of oxygen.
    The air from the bladders of some sea-weed, apparently just cast
    on shore, at the Old Passage, likewise gave the same results; so
    that, comparing these experiments with those made by Cavendish,
    Berthollet, &c. and by myself on other occasions, at different
    temperatures, in different weather, and with different winds, I
    am almost convinced that the whole of the lower stratum of the
    atmosphere is of uniform composition.

    No test can be more fallacious and imperfect than nitrous gas, on
    account of the different composition of nitrous acid, formed in the
    different manipulations of eudiometrical experiments.

    The eudiometer that I have lately employed gives, in a few minutes,
    the proportions of oxygen without correction.

    In pursuing experiments on galvanism, during the last two months,
    I have met with unexpected and unhoped-for success. Some of the
    new facts on this subject promise to afford instruments capable of
    destroying the mysterious veil which Nature has thrown over the
    operations and properties of ethereal fluids.

    Galvanism I have found, by numerous experiments, to be a _process
    purely chemical_, and to depend wholly on the oxidation of metallic
    surfaces, having different degrees of electric conducting power.

    Zinc is incapable of decomposing _pure_ water; and if the zinc
    plates be kept moist with _pure_ water, the galvanic pile does not
    act; but zinc is capable of oxidating itself when placed in contact
    with water, holding in solution either oxygen, atmospheric air,
    or nitrous or muriatic acid, &c.: and under such circumstances,
    the galvanic phenomena are produced, and their intensity is in
    proportion to the rapidity with which the zinc is oxidated.

    The galvanic pile only acts for a few minutes, when introduced into
    hydrogen, nitrogen, or hydro-carbonate; that is, only as long as
    the water between its plates holds some oxygen in solution: immerse
    it for a few moments in water containing air, and it acts again.

    It acts very vividly in oxygen gas, and less so in the atmosphere.
    When its plates are moistened by marine acid, its action is very
    powerful, but infinitely more so when nitrous acid is employed.
    Five plates with nitrous acid gave sparks equal to those of the
    common pile. From twenty plates the shock was insupportable.

    I had almost forgotten to mention, that charcoal is a good galvanic
    exciter, and decomposes water, like the metals, in the pile; but
    I must stop, without being able to expatiate on the connection
    which is now obvious between galvanism and some of the phenomena
    of organic motion. I never consider the subject without having
    forcibly impressed upon my imagination your observations[32] on the
    science of the ethereal fluids, and I cannot help flattering myself
    that this age will see your predictions verified. I remain with
    sincere respect and affection,

    Yours,
    HUMPHRY DAVY.

  [32] On conversing with Mr. Gilbert on the above passage, I
  understand that it is an allusion to his opinion, that the
  discovery of Galvanic power would ultimately lead to a knowledge
  of the nature of light and heat.


That a work, of the character of the "RESEARCHES," replete with
ingenious novelty, and rich in chemical discovery, proceeding
from the pen of so young a man, should have excited very general
admiration in the philosophic world, is a circumstance that cannot
surprise us; but in a majority of cases, precocious merit enjoys
only an ephemeral popularity; the sensations it excites are too
vivid to be permanent, and the individual sinks into an obscurity
rendered ten times more profound by the brilliancy of the flash
which preceded it; but every event of Davy's life would appear
as if created, and directed for his welfare, by some presiding
genius, whose activity, in throwing opportunities in his way was
rivalled only by the address with which he converted them to his
advantage. Fortune and talent, then, were both equally engaged
in accomplishing the elevation of Davy, and it is probable that
eminent success generally requires a combination of these elements
for its production, and that the maxim of Plautus is therefore as
remote from truth as that of Theophrastus, the one assigning all to
fortune, the other all to talent.

The experiments to which allusions have been frequently made
during the present chapter, favourably as they were received,
might have shared the fate of many other discoveries which did
not admit of an immediate and obvious application to the purposes
of common life; for statistical value is a necessary passport to
popular favour. Fortunately, however, for Davy, before the vivid
impression produced by his new work had lost the glow of novelty,
Count Rumford was anxiously seeking for some rising philosopher,
who might contribute his energies towards the support, and farther
increase, of the chemical fame of the recently established
"INSTITUTION OF GREAT BRITAIN."

It is not surprising that his attention should have been readily
directed to one whose genius had been so lately displayed, and
whose views regarding Caloric[33] were in such exact conformity
with his own opinions.

  [33] Mr. Gilbert no sooner discovered the tendency of Davy's
  opinions respecting the immateriality of Caloric, than he urged
  him to communicate them to Count Rumford, but he considered
  himself pledged to Dr. Beddoes, and his Essays were accordingly
  printed in the West Country Contributions. Count Rumford, it may
  be observed, maintained that Caloric, like _Phlogiston_, was
  merely a creature of the chemist's imagination, and had no real
  existence. He considered heat as nothing more than the motions
  of the constituent particles of bodies amongst themselves,--an
  hypothesis which has no claims to novelty, being perhaps one
  of the most ancient on record.--See his paper on Heat, _Phil.
  Trans._ for 1804.

As the philosophical public must feel a lively interest in every
incident connected with a transaction so important to the interests
of science, as that by which Davy was placed in the chemical chair
of the Institution, I am fortunate in being able, through the
kindness of his two friends, Mr. Thomson and Mr. Underwood, to
present a clear and satisfactory statement of all its circumstances
and details.




CHAPTER III.

   Count Rumford negotiates with Mr. Underwood on the subject of
   Davy's appointment to the Royal Institution.--Terms of his
   engagement communicated in a letter to Mr. Gilbert.--Davy
   arrives, and takes possession of his apartments.--He
   receives various mortifications.--He is elected a member
   of the Tepidarian Society.--Is appointed Lecturer instead
   of assistant.--He makes a tour in Cornwall with Mr.
   Underwood.--Anecdotes.--His Poem on Spinosism.--His letter to
   Mr. Gilbert, communicating a galvanic discovery.--He commences
   his first grand course of lectures.--His brilliant success.--A
   letter from Mr. Purkis.--Davy's style criticised.--His
   extraordinary method of experimenting.--Davy and Wollaston
   compared as experimentalists.--The style of Davy as a lecturer
   and a writer contrasted.


It may be readily supposed that the prominent situation held
by Davy at Bristol, as well as the merited celebrity of his
writings, must have rendered his name familiar to all the leading
philosophers of the day. It were vain, therefore, to enquire
through what channel the echo of his fame first reached the ear of
Count Rumford;[34] it is sufficient to state that Mr. Underwood,
a gentleman ardently attached to science, and devoted to the
interests of the Royal Institution, was amongst the first to urge
the expediency of inviting him to London as a public lecturer. Mr.
Underwood, in a letter lately addressed to me from Paris, says, "In
consequence of several conversations with Count Rumford, on the
subject of Davy's superior talents, and the advantages that would
accrue to the Institution from engaging him as a lecturer, the
Count called upon me on the 5th of January 1801, having received
from the Managers of the Institution full powers to negotiate upon
the subject. On this occasion, however, I thought it advisable
to introduce the Count to Mr. James Thomson, as being the more
eligible person to treat in behalf of Davy, not only on account of
his greater intimacy with him, but because, not being a proprietor,
he was unconnected with the interests of the Institution."

  [34] Amongst other celebrated chemists who had become
  acquainted with Davy at Bristol, and subsequently spoken of
  his extraordinary genius, was Dr. Hope. He informs me that
  Count Rumford had applied to him to find some chemist who would
  undertake the office of lecturer at the Institution; but that he
  failed in discovering such a person as he could, with propriety,
  introduce; some time afterwards, however, he became acquainted
  with Davy, and having soon perceived his talents, recommended
  him without any hesitation to the patronage of the Count. This
  circumstance, combined with several others, no doubt might have
  had its influence in deciding the fate of Davy.

Mr. Thomson, who saw the prospect of honour and emolument thus
opened for his friend, after a satisfactory interview with Count
Rumford, immediately wrote to Davy, with an earnest recommendation
that he should, without loss of time, come to town, and conclude an
arrangement thus auspiciously commenced.

Davy, with his characteristic ardour, answered the letter in person.
He was introduced to the Managers, and the preliminary arrangements were
soon completed; the nature of which is disclosed by himself in the
following letter to Mr. Gilbert.


    Hotwells, March 8, 1801.

    I cannot think of quitting the Pneumatic Institution, without
    giving you intimation of it in a letter; indeed, I believe I should
    have done this some time ago, had not the hurry of business, and
    the fever of emotion produced by the prospect of novel changes in
    futurity, destroyed to a certain extent my powers of consistent
    action.

    You, my dear Sir, have behaved to me with great kindness, and
    the little ability I possess you have very much contributed to
    develope; I should therefore accuse myself of ingratitude, were I
    to neglect to ask your approbation of the measures I have adopted
    with regard to the change of my situation, and the enlargement of
    my views in life.

    In consequence of an invitation from Count Rumford, given to me
    with some proposals relative to the Royal Institution, I visited
    London in the middle of February, where, after several conferences
    with that gentleman, I was invited by the Managers of the Royal
    Institution to become the Director of their laboratory, and their
    Assistant Professor of chemistry; at the same time I was assured
    that, within the space of two or three seasons, I should be made
    sole Professor of Chemistry, still continuing Director of the
    laboratory.

    The immediate emolument offered was sufficient for my wants; and
    the sole and uncontrolled use of the apparatus of the Institution,
    for private experiments, was to be granted me.

    The behaviour of Count Rumford, Sir Joseph Banks, Mr. Cavendish,
    and the other principal managers, was liberal and polite; and they
    promised me any apparatus that I might need for new experiments.

    The time required to be devoted to the services of the Institution
    was but short, being limited chiefly to the winter and spring.
    The emoluments to be attached to the office of sole Professor of
    Chemistry are great; and, above all, the situation is permanent,
    and held very honourable.

    These motives, joined to the approbation of Dr. Beddoes, who
    with great liberality has absolved me from my engagements at the
    Pneumatic Institution, and the strong wishes of most of my friends
    in London and Bristol, determined my conduct.

    Thus I am quickly to be transferred to London, whilst my sphere
    of action is considerably enlarged, and as much power as I could
    reasonably expect, or even wish for at my time of life, secured to
    me without the obligation of labouring at a profession.

    The Royal Institution will, I hope, be of some utility to society.
    It has undoubtedly the capability of becoming a great instrument
    of moral and intellectual improvement. Its funds are very great.
    It has attached to it the feelings of a great number of people
    of fashion and property, and consequently may be the means of
    employing, to useful purposes, money which would otherwise be
    squandered in luxury, and in the production of unnecessary labour.

    Count Rumford professes that it will be kept distinct from party
    politics; I sincerely wish that such may be the case, though I
    fear it.[35] As for myself, I shall become attached to it full of
    hope, with the resolution of employing all my feeble powers towards
    promoting its true interests.

    So much of my paper has been given to pure egotism, that I have but
    little room left to say any thing concerning the state of science,
    and the public mind in town; unfortunately, there is little to say.
    I have heard of no important discoveries. In politics, nothing
    seems capable of exciting permanent interest. The stroke of
    poverty, though severely felt, has been a torpedo, benumbing all
    energy, and not irritating and awakening it, as might have been
    expected.

    Here, at the Pneumatic Institution, the nitrous oxide has evidently
    been of use. Dr. Beddoes is proceeding in the execution of his
    great popular physiological work, which, if it equals the plan he
    holds out, ought to supersede every work of the kind.

    I have been pursuing Galvanism with labour, and some success. I
    have been able to produce galvanic power from simple plates, by
    effecting on them different oxidating and deoxidating processes;
    but on this point I cannot enlarge in the small remaining space of
    paper.

    Your remark concerning _negative_ Galvanism, and deoxidation, is
    curious, and will most probably hold good.

    It will give me much pleasure to see your mathematical Paper[36]
    in the Philosophical Transactions, but it will be, unfortunately,
    to me the pleasure of _blind_ sympathy, though derived from the
    consciousness that you ought to be acting upon, and instructing the
    world at large.

    It will give me sincere pleasure to hear from you, when you are at
    leisure. After the 11th I shall be in town--my direction, Royal
    Institution, Albemarle Street. I am, my dear friend, with respect
    and affection, Yours,

    HUMPHRY DAVY.

  [35] In England, politics so constantly mix themselves up with
  all our institutions, while science unfortunately finds so few
  disciples and patrons in the ranks of aristocracy, that every new
  society is viewed with jealousy and party spirit. Johnson says,
  in his Life of Addison--"It has been suggested that the Royal
  Society was instituted soon after the Restoration, to divert the
  attention of the people from public discontent."--P.

  [36] He alludes to some calculations connected with light, and
  the imponderable fluids.


The first notice of Davy's name, in the Minute Book of the Royal
Institution, occurs in the Report adopted at a Meeting of the
Managers, on Monday the 16th of February 1801.

"Resolved--That Mr. Humphry Davy be engaged in the service of the
Royal Institution, in the capacities of Assistant Lecturer in
Chemistry, Director of the Laboratory, and Assistant Editor of the
Journals of the Institution, and that he be allowed to occupy a
room in the house, and be furnished with coals and candles; and
that he be paid a salary of one hundred guineas per annum."

On the 16th of March 1801, after reporting that "a room had been
prepared and furnished for Davy," the Minute proceeds to state that
"Mr. Davy had arrived at the Institution on Wednesday the 11th of
March, and taken possession of his situation."

It is a curious fact, that the first impression produced on Count
Rumford by Davy's personal appearance, was highly unfavourable to
the young philosopher, and he expressed to Mr. Underwood his great
regret at having been influenced by the ardour with which his suit
had been urged; and he actually would not allow him to lecture in
the Theatre, until he had given a specimen of his abilities in the
smaller lecture-room. His first lecture, however, entirely removed
every prejudice which had been formed; and at its conclusion the
Count emphatically exclaimed--"Let him command any arrangements
which the Institution can afford." He was accordingly, on the very
next day, promoted to the great Theatre.

Davy's uncouth appearance and address subjected him to many other
mortifications on his first arrival in London. There was a smirk
on his countenance, and a pertness in his manner, which, although
arising from the perfect simplicity of his mind, were considered
as indicating an unbecoming confidence. Johnson, the publisher,
as many of my readers will probably remember, was in the custom
of giving weekly dinners to the more distinguished authors and
literary stars of the day. Davy, soon after his appointment,
was invited upon one of these occasions, but the host actually
considered it necessary to explain, by way of apology, to his
company, the motives which had induced him to introduce into their
society a person of such humble pretensions. At this dinner a
circumstance occurred, which must have been very mortifying to
the young philosopher. Fuseli was present, and, as usual, highly
energetic upon various passages of beauty in the poets, when Davy
most unfortunately observed, that there were passages in Milton
which he could never understand. "Very likely, very likely, Sir,"
replied the artist in his broad German accent, "but I am sure that
is not Milton's fault."

On the 7th of April, he was elected a member of a society which
consisted of twenty-five of the most violent republicans of
the day; it was called the "_Tepidarian_ Society," from the
circumstance of nothing but tea being allowed at their meetings,
which were held at Old Slaughter's Coffee House in Saint Martin's
Lane. To the influence of this society, Mr. Underwood states that
Davy was greatly indebted for his early popularity. Fame gathers
her laurels with a slow hand, and the most brilliant talents
require a certain time for producing a due impression upon the
public; the _Tepidarians_ exerted all their personal influence to
obtain an audience before the reputation of the lecturer could have
been sufficiently known to attract one.

Although the acquaintance between Davy and Count Rumford commenced
so inauspiciously, they very soon became friends, and mutually
entertained for each other the highest regard.

Davy's improved manners and naturally simple habits, at this
period, were highly interesting and exemplary: towards his old
friends he conducted himself with the greatest amenity, and
frequently consulted them upon certain points connected with his
new station in society. The following anecdote was communicated
by Mr. Underwood.--"I introduced him," says he, "to my old
friend, the excellent Sir Henry Englefield, who was the first
intimate acquaintance Davy had formed in the higher circles; he
was received by him with all that warmth of manner, and kindness
of feeling, which so eminently distinguished him. Shortly after
this introduction, Sir Harry sent him an invitation to meet
me at dinner. Davy found himself unable to frame an answer to
his satisfaction, and fearing he might betray his ignorance of
etiquette, ran to my house, and greatly alarmed my mother by the
extreme anxiety he displayed, and the manner in which he entreated
her to send me to him the moment I returned. I went and found him
cudgelling his brains to produce this first attempt at fashionable
composition; a dozen answers were on his table, and he was in the
highest degree excited and annoyed."

It would appear that, immediately after his arrival at the Royal
Institution, he entered upon the duties of his station, and
performed them so greatly to the satisfaction of the Managers,
that, at a Meeting held on the first of June, not more than six
weeks afterwards, the following Resolutions were passed.

"Resolved--That Mr. Humphry Davy, Director of the Chemical
Laboratory, and Assistant Lecturer in Chemistry, has, since he has
been employed at the Institution, given satisfactory proofs of his
talents as a Lecturer.

"Resolved--That he be appointed, and in future denominated,
Lecturer in Chemistry at the Royal Institution, instead of
continuing to occupy the place of _Assistant_ Lecturer, which he
has hitherto filled."

From an examination of the Minute Book, it appears that Dr.
Garnett, whose health had long been on the decline, resigned his
professorship on the 15th of June,[37] and that on the 6th of July
in the same year, Dr. Young was engaged as Professor of Natural
Philosophy, Editor of the Journals, and general Superintendent of
the House, at the salary of 300_l._ per annum.

  [37] He delivered his farewell Lecture on the 9th of the same
  month.

With Dr. Garnett he had lived on terms of great intimacy; with his
successor he associated with less ease and freedom.

At a meeting of the Managers, also held in July, several
Resolutions were passed to the following effect.

"Resolved--That a Course of Lectures on the Chemical Principles of
the Art of Tanning be given by Mr. Davy. To commence the second of
November next; and that respectable persons of the trade, who shall
be recommended by Proprietors of the Institution, be admitted to
these lectures gratis.

"Resolved further--That Mr. Davy have permission to absent himself
during the months of July, August, and September, for the purpose
of making himself more particularly acquainted with the practical
part of the business of tanning, in order to prepare himself for
giving the above-mentioned course of lectures."

Davy, it would appear, availed himself of the permission granted
to him by the above resolution of the Managers, and during the
interval visited his native country.

He had arranged with his friend Underwood to make a tour through
Cornwall; but as it was his wish to remain at Bristol for a few
days, on his way to the West, it was agreed between them that they
should meet at Penzance.

Davy, however, became impatient, and wrote the following letter to
his friend, a composition of much wildness, and obnoxious to the
suspicion of Spinosism.


    MY DEAR UNDERWOOD,

    That part of Almighty God which resides in the rocks and woods,
    in the blue and tranquil sea, in the clouds and sunbeams of the
    sky, is calling upon thee with a loud voice: religiously obey its
    commands, and come and worship with me on the ancient altars of
    Cornwall.

    I shall leave Bristol on Thursday next, possibly before, so that
    by this day week I shall probably be at Penzance. Ten days or a
    fortnight after, I shall expect to see you, and to rejoice with you.

    We will admire together the wonders of God,--rocks and the sea,
    dead hills and living hills covered with verdure. Amen.

    Write to me immediately, and say when you will come. Direct H.
    Davy, Penzance. Farewell, Being of energy!

    Your's with unfeigned affection,
    H. DAVY.


Mr. Underwood transmitted to me the above letter with the following
extract from his journal.

"On the 25th I went to Bristol, and on the 30th arrived at Mrs.
Davy's at Penzance. On the 1st of August we set off on a pedestrian
excursion, and proceeded along the edge of the cliffs, round the
Land's End, Cape Cornwall, Saint Just, and Saint Ives, to Redruth,
and thence back to Penzance.

"Two days afterwards we again started, and trudged along the
shore to the Lizard. Kynance Cove had from the commencement of
our intimacy been a daily theme of his conversation. No epithets
were sufficiently forcible to express his admiration at the beauty
of the spot: the enthusiastic delight with which he dwelt upon
the description of the Serpentine rocks, polished by the waves,
and reflecting the brightest tints from their surfaces, seemed
inexhaustible, and when we had arrived at the spot he appeared
absolutely entranced.

"During these excursions his conversation was most romantic and
poetical. His views of Nature, and her sublime operations, were
expressed without reserve, as they rapidly presented themselves
to his imagination: they were the ravings of genius; but even his
nonsense was that of a superior being."

At the village of Mullion, a little incident occurred, which
evinced the existence of that gastronomic propensity which, in
after years, displayed itself in a wider range of operations. The
tourists had, on their road, purchased a fine large bass of a
fisherman, with the intention of desiring the landlady to dress it.
On arriving at the inn, Mr. Underwood retired into a room for the
purpose of making some notes in the journal he regularly kept. Davy
had disappeared. In the course of a few minutes a most tremendous
uproar was heard in the kitchen, and the indignant vociferations
of the hostess, which, even with all the advantages of Cornish
recitative, was not of the most melodious description, became
fearfully audible. Davy, it seems, had volunteered his assistance
in making the sauce and stuffing for the aforesaid bass; and had
he not speedily retreated, his services would have been rewarded,
not according to the scientific practice of appending a string of
letters to his name, but in conformity with the equally ancient
custom of attaching a certain dishonourable addition to the skirts
of his jacket.

I have observed that his letter to Mr. Underwood betrayed a
tincture of _Spinosism_. It may be here remarked, that during the
year 1801 he composed a poem, which he arbitrarily distinguished
by that appellation, singularly opposed to the tenor of the
sentiments. Through the kindness of Mr. Greenough I possess a copy
of it in its original state, for it was subsequently altered, and
published in a collection, edited by Miss Johanna Baillie; and
still more recently, it underwent farther corrections, and was
printed for private circulation in the form in which I shall here
introduce it.


    Lo! o'er the Earth the kindling spirits pour
      The flames of life, that bounteous Nature gives;
    The limpid dew becomes the rosy flower;
      The insensate dust awakes, and moves, and lives.

    All speaks of change: the renovated forms
      Of long forgotten things arise again.
    The light of suns, the breath of angry storms,
      The everlasting motions of the main;

    These are but engines of the Eternal Will,
      The One Intelligence; whose potent sway
    Has ever acted, and is acting still,
      Whilst stars, and worlds, and systems, all obey:

    Without whose power, the whole of mortal things
      Were dull, inert, an unharmonious band;
    Silent as are the harp's untuned strings
      Without the touches of the poet's hand.

    A sacred spark, created by His breath,
      The immortal mind of man his image bears;
    A spirit living midst the forms of death,
      Oppress'd but not subdued by mortal cares--

    A germ, preparing in the winter's frost,
      To rise and bud and blossom in the spring;
    An unfledged eagle by the tempest tost,
      Unconscious of his future strength of wing:--

    The child of trial, to mortality,
      And all its changeful influences given:
    On the green earth decreed to move and die;
      And yet by such a fate prepared for Heaven.--

    Soon as it breathes, to feel the mother's form
      Of orbed beauty, through its organs thrill;
    To press the limbs of life with rapture warm,
      And drink of transport from a living rill:

    To view the skies with morning radiance bright,
      Majestic mingling with the ocean blue,
    Or bounded by green hills, or mountains white;
      Or peopled plains of rich and varied hue:

    The nobler charms astonish'd to behold
      Of living loveliness, to see it move,
    Cast in expression's rich and varied mould,
      Awakening sympathy, compelling love:--

    The heavenly balm of mutual hope to taste,
      Soother of life; affection's bliss to share,
    Sweet as the stream amidst the desert waste,
      As the first blush of arctic daylight fair:--

    To mingle with its kindred, to descry
      The path of power--in public life to shine;
    To gain the voice of popularity;
      The idol of to-day, the man divine:--

    To govern others by an influence strong
      As that high law, which moves the murm'ring main;
    Raising and carrying all its waves along,
      Beneath the full-orb'd moon's meridian reign:--

    To scan how transient is the breath of praise;
      A winter's zephyr trembling on the snow,
    Chill'd as it moves; or as the northern rays,
      First fading in the centre, whence they flow:--

    To live in forests mingled with the whole
      Of natural forms, whose generations rise
    In lovely change, in happy order roll
      On land, in ocean, in the glittering skies:--

    Their harmony to trace--The Eternal Cause
      To know in love, in reverence to adore--
    To bend beneath the inevitable law,
      Sinking in death; its human strength no more:--

    Then, as awakening from a dream of pain,
      With joy its mortal feelings to resign;
    Yet all its living essence to retain,
      The undying energy of strength divine:

    To quit the burdens of its earthly days,
      To give to Nature all her borrow'd powers;
    Ethereal fire to feed the solar rays,
      Ethereal dew to glad the earth in showers.


The following letter was written from London, after his return from
his Cornish excursion.


    TO DAVIES GIDDY, ESQ.

    Royal Institution, Nov. 14, 1801.

    MY DEAR SIR,

    After leaving Cornwall in August, I spent about three weeks in
    Bristol, and at Stowey, so that I did not arrive in London until
    the 20th of September.

    On my arrival I found that Count Rumford had altered his plans of
    absence, and had left London on that very day for the Continent,
    purposing to return in about two months. He is now at Paris, and in
    about a fortnight we expect him here.

    I shall soon have an opportunity of submitting Captain Trevitheck's
    boiler to his observation, and in my next letter I shall give you
    his opinion of it.

    You of course have read an account of Dr. Herschel's experiments on
    the heat-making rays; from some late observations it appears, that
    there are other invisible rays beyond the violet ones, possessed of
    the _chemical_ agency of Light. Sennebier ascertained some time ago
    that the violet rays blackened muriate of silver in three seconds;
    whereas the red rays required, for this effect, twenty minutes.
    Ritter and Dr. Wollaston have found that beyond the violet rays
    there is exerted a strong deoxidating action. Muriate of silver
    placed in the spectrum is not altered beyond the red rays; but it
    is instantly blackened when placed on the outside of the violet
    rays. I purpose to try whether the invisible deoxidating rays will
    produce light, when absorbed by solar phosphorus.

    The most curious galvanic facts lately noticed, are the combustion
    of gold, silver, and platina. Professor Tromsdorf, by connecting
    the ends of a moderately strong battery with gold and silver leaf,
    produced the combustion of them with vivid light. In repeating the
    experiment on a thin slip of platina, I have produced the same
    effect.

    I yesterday ascertained rather an important fact, namely, that
    a galvanic battery may be constructed _without any metallic
    substance_! By means of ten pieces of well-burnt charcoal, nitrous
    acid, and water, arranged alternately in wine-glasses, I produced
    all the effects usually obtained from zinc, silver, and water.

    The Bakerian Lecture by Dr. Young, our Lecturer on Natural
    Philosophy, is now reading before the Royal Society. He attempts to
    revive the doctrine of Huygens and Euler, that light depends upon
    undulations of an ethereal medium. His proofs (i.e. his presumptive
    proofs) are drawn from some strong and curious analogies he has
    discovered between Light and Sound.

    I shall strongly hope, now the Peace has arrived, to see you soon
    in London, as you proposed a tour through the Continent; indeed,
    you should fix your permanent residence in London, where alone you
    can do what you ought--instruct and delight numbers of improved men.

    I am, my friend, yours
    With unfeigned esteem and respect,
    HUMPHRY DAVY.


Although during 1801 Davy had given some desultory Lectures,
his splendid career cannot be said to have commenced until the
following year, when on the 21st of January he delivered his
Introductory Lecture to a crowded and enlightened audience in the
Theatre of the Royal Institution; which was afterwards printed at
the request of a respectable proportion of the Society.

It contains a masterly view of the benefits to be derived from the
various branches of science. He represents the Chemist as the Ruler
of all the elements that surround us, and which he employs either
for the satisfaction of his wants, or the gratification of his
wishes. Not contented with what is to be found on the surface of
the earth, he describes him as penetrating into her bosom, and even
of searching the depths of the ocean, for the purpose of allaying
the restlessness of his desires, or of extending and increasing the
boundaries of his power.

In examining the science of Chemistry, with regard to its great
agency in the improvement of society, he offers the following
almost prophetic remarks. "Unless any great physical changes should
take place upon the globe, the permanency of the Arts and Sciences
is rendered certain, in consequence of the diffusion of knowledge,
by means of the invention of Printing; and by which those words
which are the immutable instruments of thought, are become the
constant and widely diffused nourishment of the mind, and the
preservers of its health and energy.

"Individuals influenced by interested motives or false views, may
check for a time the progress of knowledge;--moral causes may
produce a momentary slumber of the public spirit;--the adoption
of wild and dangerous theories, by ambitious or deluded men, may
throw a temporary opprobrium on literature; but the influence of
true philosophy will never be despised; the germs of improvement
are sown in minds, even where they are not perceived; and sooner or
later, the spring-time of their growth must arrive.

"In reasoning concerning the future hopes of the human species,
we may look forward with confidence to a state of society, in
which the different orders and classes of men will contribute more
effectually to the support of each other than they have hitherto
done. This state, indeed, seems to be approaching fast; for, in
consequence of the multiplication of the means of instruction,
the man of science and the manufacturer are daily becoming more
assimilated to each other. The artist, who formerly affected
to despise scientific principles, because he was incapable of
perceiving the advantages of them, is now so far enlightened as to
favour the adoption of new processes in his art, whenever they are
evidently connected with a diminution of labour; and the increase
of projectors, even to too great an extent, demonstrates the
enthusiasm of the public mind in its search after improvement.

"The arts and sciences, also, are in a high degree cultivated and
patronized by the rich and privileged orders. The guardians of
civilization and of refinement, the most powerful and respected
part of society, are daily growing more attentive to the realities
of life,--and giving up many of their unnecessary enjoyments, in
consequence of the desire to be useful, are becoming the friends
and protectors of the labouring part of the community.

"The unequal division of property and of labour, the differences
of rank and condition amongst mankind, are the sources of power
in civilized life--its moving causes, and even its very soul.
In considering and hoping that the human species is capable of
becoming more enlightened and more happy, we can only expect
that the different parts of the great whole of society should
be intimately united together, by means of knowledge and the
useful arts; that they should act as the children of one great
parent, with one determinate end, so that no power may be rendered
useless--no exertions thrown away.

"In this view, we do not look to distant ages, or amuse ourselves
with brilliant though delusive dreams, concerning the infinite
improveability of man, the annihilation of labour, disease, and
even death, but we reason by analogy from simple facts, we consider
only a state of human progression arising out of its present
condition,--we look for a time that we may reasonably expect--FOR A
BRIGHT DAY, OF WHICH WE ALREADY BEHOLD THE DAWN."

The extraordinary sensation produced amongst the members of the
Institution by this first course of lectures, has been vividly
described by various persons who had the good fortune to be his
auditors; and foreigners have recorded in their travels the
enthusiasm with which the great English chemist had inspired his
countrymen.

The members of the Tepidarian Society, sanguine in the success of
their child,--for so they considered Davy,--purposely appointed
their anniversary festival on the day of his anticipated triumph.
They were not disappointed in their hopes; and their dinner was
marked by every demonstration of hilarity. In the evening, Davy
accompanied by a few friends, attended, for the first time in his
life, a masquerade which was given at Ranelagh.

On the following day, he dined with Sir Harry Englefield. I have a
copy of the invitation, addressed to Mr. Underwood, now before me.


    DEAR UNDERWOOD,

    Davy, covered with glory, dines with me to-day at five. If you
    could meet him, it would give me great pleasure.

    Tilney Street, Friday.

    Yours truly,
    H. C. ENGLEFIELD.


At this dinner, Sir Harry wrote a request to Davy to print his
Lecture, which was signed by every one present, except Mr.
Underwood, who declined, from the apprehension that the signature
of so intimate a friend might give to that which was a spontaneous
homage to talent, the appearance of a previously concerted scheme.

I shall here weave into my narrative some extracts from several
letters, with which Mr. Purkis, one of the earliest friends of
Davy, has lately favoured me.

"On his first appointment at the Royal Institution, I was specially
introduced to him by a common friend, Thomas Poole, Esq. of Nether
Stowey in Somersetshire; and I continued in habits of friendship
with him during a great portion of his life, though somewhat less
intimately during the last few years. I loved him living--I lament
his early death: I shall ever honour his memory.

"The sensation created by his first course of Lectures at the
Institution, and the enthusiastic admiration which they obtained,
is at this period scarcely to be imagined. Men of the first rank
and talent,--the literary and the scientific, the practical and
the theoretical, blue-stockings, and women of fashion, the old
and the young, all crowded--eagerly crowded the lecture-room.
His youth, his simplicity, his natural eloquence, his chemical
knowledge, his happy illustrations and well-conducted experiments,
excited universal attention and unbounded applause. Compliments,
invitations, and presents, were showered upon him in abundance from
all quarters; his society was courted by all, and all appeared
proud of his acquaintance.

"One instance of attention is particularly recalled to my memory.
A talented lady, since well known in the literary world, addressed
him anonymously in a poem of considerable length, replete with
delicate panegyric and genuine feeling. It displayed much
originality, learning, and taste: the language was elegant, the
versification harmonious, the sentiments just, and the imagery
highly poetical. It was accompanied with a handsome ornamental
appendage for the watch, which he was requested to wear when he
delivered his next lecture, as a token of having received the poem,
and pardoned the freedom of the writer. It was long before the
fair authoress was known to him, but they afterwards became well
acquainted with each other."

I should not redeem the pledge given to my readers, nor
fulfill the duties of an impartial biographer, were I to omit
acknowledging that the manners and habits of Davy very shortly
underwent a considerable change. Let those who have vainly
sought to disparage his excellence, enjoy the triumph of knowing
that he was not perfect; but it may be asked in candour, where
is the man of twenty-two years of age, unless the temperature
of his blood were below zero, and his temperament as dull and
passionless as the fabled god of the Brahmins, who could remain
uninfluenced by such an elevation? Look at Davy in the laboratory
at Bristol, pursuing with eager industry various abstract points
of research; mixing only with a few philosophers, sanguine like
himself in the investigation of chemical phenomena, but whose
sphere of observation must have been confined to themselves, and
whose worldly knowledge could scarcely have extended beyond the
precincts of the Institution in which they were engaged. Shift
the scene--behold him in the Theatre of the Royal Institution,
surrounded by an aristocracy of intellect as well as of rank; by
the flowers of genius, the _élite_ of fashion, and the beauty
of England, whose very respirations were suspended in eager
expectation to catch his novel and satisfactory elucidations of
the mysteries of Nature. Could the author of the Rambler have
revisited us, he would certainly have rescinded the passage in
which he says--"All appearance of science is hateful to women; and
he who desires to be well received by them, must qualify himself
by a total rejection of all that is rational and important; must
consider learning as perpetually interdicted, and devote all his
attention to trifle, and all his eloquence to compliment."

It is admitted that his vanity was excited, and his ambition
raised, by such extraordinary demonstrations of devotion; that the
bloom of his simplicity was dulled by the breath of adulation; and
that, losing much of the native frankness which constituted the
great charm of his character, he unfortunately assumed the garb
and airs of a man of fashion; let us not wonder if, under such
circumstances, the inappropriate robe should not always have fallen
in graceful draperies.

At length, so popular did he become, under the auspices of the
Duchess of Gordon and other leaders of high fashion, that even
their _soirées_ were considered incomplete without his presence;
and yet these fascinations, strong as they must have been, never
tempted him from his allegiance to Science: never did the charms
of the saloon allure him from the pursuits of the laboratory, or
distract him from the duties of the lecture-room. The crowds that
repaired to the Institution in the morning were, day after day,
gratified by newly devised and highly illustrative experiments,
conducted with the utmost address, and explained in language at
once perspicuous and eloquent.

He brought down Science from those heights which were before
accessible only to a few, and placed her within the reach of all;
he divested the goddess of all severity of aspect, and represented
her as attired by the Graces.

It is perhaps not possible to convey a better idea of the
fascination of his style, than by the relation of the following
anecdote. A person having observed the constancy with which Mr.
Coleridge attended these lectures, was induced to ask the poet what
attractions he could find in a study so unconnected with his known
pursuits. "I attend Davy's lectures," he replied, "to increase my
stock of metaphors."

But, as Johnson says, in the most general applause some discordant
voices will always be heard; and so was it upon the present
occasion. It was urged by several modern _Zoili_, that the style
was far too florid and imaginative for communicating the plain
lessons of truth; that he described objects of Natural History
by inappropriate imagery, and that violent conceits frequently
usurped the place of philosophical definitions. This was Boeotian
criticism; the Attic spirits selected other points of attack:
they rallied him on the ground of affectation, and whimsically
represented him as swayed by a mawkish sensibility, which
constantly betrayed him into absurdity. There might be some show
of justice in this accusation: The world was not large enough to
satisfy the vulgar ambition of the conqueror, but the minutest
production of nature afforded ample range for the scrutinizing
intelligence of the philosopher; and he would consider a particle
of crystal with so delicate a regard for its minute beauties,
and expatiate with so tender a tone of interest on its fair
proportions, as almost to convey an idea that he bewailed the
condition of necessity which for ever allotted it so slender a
place in the vast scheme of creation.

After the observations which have been offered with regard to
the injurious tendency of metaphors in all matters relating to
science, I may probably be charged with inconsistency in defending
Davy from the attacks thus levelled against his style. We need
not the critic to remind us that the statue of a Lysippus may
be spoiled by gilding; but I would observe that the style which
cannot be tolerated in a philosophical essay, may under peculiar
circumstances be not only admissible, but even expedient, in a
popular lecture. "_Neque ideo minus efficaces sunt orationes nostræ
quia ad aures judicantium cum voluptate perveniunt. Quid enim si
infirmiora horum temporum templa credas, quia non rudi cæmento,
et informibus tegulis exstruuntur; sed marmore nitent et auro
radiantur?_"

Let us consider, for a moment, the class of persons to whom Davy
addressed himself. Were they students prepared to toil with
systematic precision, in order to obtain knowledge as a matter
of necessity?--No--they were composed of the gay and the idle,
who could only be tempted to admit instruction by the prospect of
receiving pleasure,--they were children, who could only be induced
to swallow the salutary draught by the honey around the rim of the
cup.

It has been well observed, that necessity alone can urge the
traveller over barren heaths and snow-topped mountains, while he
treads with rapture along the fertile vales of those happier climes
where every breeze is perfume, and every scene a picture.

If Science can be promoted by increasing the number of its
votaries, and by enlisting into its service those whom wealth
and power may render valuable as examples or patrons, there does
not exist a class of philosophers to which we are more largely
indebted than to popular lecturers, or to those whose eloquence has
clothed with interest, subjects otherwise severe and uninviting.
How many disciples did Mineralogy acquire through the lectures of
Dr. Clarke at Cambridge, who may truly be said to have covered a
desert with verdure, and to have raised from barren rocks flowers
of every hue and fragrance! In the sister university, what an
accession of strength and spirit have the animated discourses of
Dr. Buckland brought to the ranks of Geologists! To judge fairly
of the influence of a popular style, we should acquaint ourselves
with the effects of an opposite method; and if an appeal be made
to experience, I may very safely abide the issue. Dr. Young, whose
profound knowledge of the subjects he taught, no one will venture
to question, lectured in the same theatre, and to an audience
similarly constituted to that which was attracted by Davy, but he
found the number of his attendants diminish daily, and for no other
reason than that he adopted too severe and didactic a style.[38]

  [38] From the following minute it would appear, that Dr. Young's
  connection with the Royal Institution was but of short duration.
  It will be remembered that his appointment took place on July 6,
  1801.

  "Resolved--That Dr. Young be paid the balance of two years'
  complete salary, and that his engagement with the Institution
  terminate from this time--July 4, 1803."

In speaking of Davy's lectures as mere specimens of happy oratory,
we do injustice to the philosopher. Had he merely added the
Corinthian foliage to a temple built by other hands, we might have
commended his taste, and admired his talent of adaptation, and
there our eulogium must have ended; but the edifice itself was
his own; he dug the materials from the quarry, formed them into
a regular pile, and then with his masterly touch added to its
strength beauty, and to its utility grace.

In addition to these morning lectures, we find that he was also
engaged in delivering a course in the evening; of which the
following notice is extracted from one of the scientific journals
of the time. "On the 25th, Mr. Davy commenced a course of lectures
on Galvanic phenomena. Sir Joseph Banks, Count Rumford, and other
distinguished philosophers, were present. The audience were highly
gratified, and testified their satisfaction by general and repeated
applause.

"Mr. Davy, who appears to be very young, acquitted himself
admirably. From the sparkling intelligence of his eye, his animated
manner, and the _tout ensemble_, we have no doubt of his attaining
a very distinguished eminence."

From a Minute entered on the Records of the Institution, it appears
that, at a meeting of Managers held on the 31st of May 1802, it was
moved by Sir Joseph Banks, and seconded by Mr. Sullivan,--

"That Mr. Humphry Davy be for the future styled _Professor of
Chemistry_ to the Royal Institution."

A sufficient proof of the universal feeling of admiration which his
lectures had excited.

The success of his exertions is communicated by him to his early
friend, in the following letter.


    TO DAVIES GIDDY, ESQ.

    DEAR FRIEND,

    Since the commencement of the Session at the Institution, I have
    had but few moments of leisure. The composition of a first course
    of lectures, and the preparation for experiments, have fully
    occupied my time; and the anxieties and hopes connected with a
    new occupation have prevented me from paying sufficient attention
    even to the common duties and affections of life. Under such
    circumstances, I trust you will pardon me for having suffered
    your letters to remain so long unanswered. In human affairs,
    anticipation often constitutes happiness: your correspondence is to
    me a real source of pleasure, and, believe me, I would suffer no
    opportunity to escape of making it more frequent and regular.

    My labours in the Theatre of the Royal Institution have been
    more successful than I could have hoped from the nature of them.
    In lectures, the effect produced upon the mind is generally
    transitory; for the most part, they amuse rather than instruct, and
    stimulate to enquiry rather than give information. My audience has
    often amounted to four and five hundred, and upwards; and amongst
    them some promise to become permanently attached to Chemistry.
    This science is much the fashion of the day.

    Amongst the latest scientific novelties, the two new planets occupy
    the attention of Astronomers, while Natural Philosophers and
    Chemists are still employed upon Galvanism.

    In a paper lately read before the Royal Society, Dr. Herschel
    examines the magnitudes of the bodies discovered by Mr. Piazzi
    and Dr. Olbers. He supposes the apparent diameter of Ceres to
    be about 22´´, and that of Pallas, 17´´ or 13´´, so that their
    real diameters are 163, and 95 or 71 English miles--How small!
    The Doctor thinks that they differ from planets in their general
    character, as to their diminutive size, the great inclination of
    their orbits, the coma surrounding them, and as to the proximity of
    their orbits.--From comets, in their want of their eccentricity,
    and any considerable nebulosity. He proposes to call them
    _Asteroids_.

    I mentioned to you in a former letter the great powers of
    Galvanism in effecting the combustion of metals. I have lately had
    constructed for the laboratory of the Institution, a battery of
    immense size: it consists of four hundred plates of five inches in
    diameter, and forty, of a foot in diameter. By means of it, I have
    been enabled to inflame cotton, sulphur, resin, oil, and ether; it
    fuses platina wire, and makes red hot and burns several inches of
    iron wire of 1-300th of an inch in diameter; it easily causes fluid
    substances, such as oil and water, to boil, decompounds them, and
    converts them into gases. I am now examining the agencies of it
    upon certain substances that have not as yet been decomposed, and
    in my next letter I hope to be able to give you an account of my
    experiments.

    I shall hope soon to hear that the roads of England are the
    haunts of Captain Trevitheck's dragons. You have given them a
    characteristic name.

    I wish any thing would happen to tempt you to visit London. You
    would find a number of persons very glad to see you, with whose
    attentions you could not be displeased. With unfeigned respect,

    Yours sincerely,
    H. DAVY.


It is perhaps not possible to imagine a greater contrast, than
between the elegant manner in which Davy conducted his experiments
in the theatre, and the apparently careless and slovenly style of
his manipulations in the laboratory: but in the one case he was
communicating knowledge; in the other, obtaining it. Mr. Purkis
relates an anecdote very characteristic of this want of refinement
in his working habits. "On one occasion, while reading over to me
an introductory lecture, and wishing to expunge a needless epithet,
instead of taking up the pen, he dipped his forefinger into the
ink-bottle, and thus blotted out the unmeaning expletive."

It was his habit in the laboratory, to carry on several unconnected
experiments at the same time, and he would pass from one to the
other without any obvious design or order: upon these occasions he
was perfectly reckless of his apparatus; breaking and destroying
a part, in order to meet some want of the moment. So rapid were
all his movements, that, while a spectator imagined he was merely
making preparations for an experiment, he was actually obtaining
the results, which were just as accurate as if a much longer time
had been expended. With Davy, rapidity was power.

The rapid performance of intellectual operations was a talent
which displayed itself at every period of his life. We have heard
with what extraordinary rapidity he read at the age of five years;
and we now learn that his chemical enquiries were conducted with
similar facility and quickness.

His early friend Mr. Poole bears his testimony to the existence
of the same quality in the following passage, extracted from a
letter I had lately the favour of receiving from him. "From my
earliest knowledge of my admirable friend, I consider his most
striking characteristic to have been the quickness and truth of
his apprehension. It was a power of reasoning so rapid, when
applied to any subject, that he could hardly be himself conscious
of the process; and it must, I think, have been felt by him, as
it appeared to me, pure intuition. I used to say to him, 'You
understand me before I half understand myself?'

"I recollect on our first acquaintance, he knew but little of the
practice of agriculture. I was at that time a considerable farmer,
and very fond of the occupation. During his visits in those days, I
was at first something like his teacher, but my pupil soon became
my master both in theory and practice."

The chemical manipulations of Wollaston and Davy offered a
singular contrast to each other, and might be considered as highly
characteristic of the temperaments and intellectual qualities of
these remarkable men. Every process of the former was regulated
with the most scrupulous regard to microscopic accuracy, and
performed with the utmost neatness of detail. It has been already
stated with what turbulence and apparent confusion the experiments
of the latter were conducted; and yet each was equally excellent in
his own style; and, as artists, they have not unaptly been compared
to Teniers and Michael Angelo. By long discipline, Wollaston had
acquired such power in commanding and fixing his attention upon
minute objects, that he was able to recognise resemblances, and
to distinguish differences, between precipitates produced by
re-agents, which were invisible to ordinary observers, and which
enabled him to submit to analysis the minutest particle of matter
with success. Davy, on the other hand, obtained his results by
an intellectual process, which may be said to have consisted in
the extreme rapidity with which he seized upon, and applied,
appropriate means at appropriate moments.

Many anecdotes might be related in illustration of the curiously
different structure of the minds of these two ornaments of British
Science. The reader will, in the course of these memoirs, be
furnished with sufficient evidence of the existence of those
qualities which I have assigned to Davy; another biographer will no
doubt ably illustrate those of Dr. Wollaston.

I shall only observe, that to this faculty of minute observation,
which Dr. Wollaston applied with so much advantage, the chemical
world is indebted for the introduction of more simple methods of
experimenting,--for the substitution of a few glass tubes, and
plates of glass, for capacious retorts and receivers, and for the
art of making grains give the results which previously required
pounds. A foreign philosopher once called upon Dr. Wollaston with
letters of introduction, and expressed an anxious desire to see his
laboratory. "Certainly," he replied; and immediately produced a
small tray containing some glass tubes, a blow-pipe, two or three
watch-glasses, a slip of platinum, and a few test bottles.

Wollaston appeared to take great delight in showing by what
small means he could produce great results. Shortly after he had
inspected the grand galvanic battery constructed by Mr. Children,
and had witnessed some of those brilliant phenomena of combustion
which its powers produced, he accidentally met a brother chemist
in the street, and seizing his button, (his constant habit when
speaking on any subject of interest,) he led him into a secluded
corner; when taking from his waistcoat pocket a tailor's thimble,
which contained a galvanic arrangement, and pouring into it the
contents of a small phial, he instantly heated a platinum wire to a
white heat.

There was another peculiarity connected with Wollaston's habit
of minute observation: it enabled him to press into his service,
at the moment, such ordinary and familiar materials as would
never have occurred to less observing chemists. Mr. Brande
relates an anecdote admirably calculated to exemplify this
habit. He had called upon Dr. Wollaston to consult him upon the
subject of a calculus;--it will be remembered that neither
phosphate of lime, constituting the '_bone earth_' species, nor
the ammoniaco-magnesian phosphate, commonly called the '_triple
phosphate_,' is _per se_ fusible; but that when mixed, these
constitute the '_fusible calculus_' which readily melts before
the blow-pipe. Dr. Wollaston, on finding the substance under
examination refractory, took up his paper-folder, and scraping
off a fragment of the ivory, placed it on the specimen, when it
instantly fused.[39]

  [39] I have lately been informed that the idea of constructing
  an instrument like the Camera Lucida, first suggested itself to
  Dr. Wollaston, on his noticing certain phenomena occasioned by a
  crack in the glass before which he was shaving himself.

Having contrasted the manipulations of Davy, as exhibited in the
theatre, with those performed by him in the laboratory, it may,
in this place, be interesting to offer a few remarks upon the
difference of his style as a lecturer and as a writer. Whatever
diversity of opinion may have been entertained as to the former,
I believe there never was but one sentiment with respect to the
latter. There is an ethereal clearness of style, a simplicity of
language, and, above all, a freedom from technical expression,
which render his philosophical memoirs fit studies and models for
all future chemists. Mr. Brande, in a late lecture delivered before
the members of the Royal Institution, very justly alluded to this
latter quality of his writings, and forcibly contrasted it with
the system of Berzelius, of whom it is painful to speak but in
terms of the most profound respect, and yet it is impossible not to
express a deep regret at this distinguished chemist's introduction
of a system of technical expressions, which from its obscurity is
calculated to multiply rather than to correct error, and from its
complications, to require more labour than the science to which it
administers: to apply the quaint metaphor of Locke, "it is no more
suited to improve the understanding, than the move of a jack is to
fill our bellies."

From the readiness with which some continental chemists have
adopted such terms, and from the spirit in which they have defended
them, one might almost be led to suspect that they believed them,
like the words used by the Magi of Persia, to possess a cabalistic
power. Davy foresaw the injury which science must sustain from
such a practice, and endeavoured, both by precept and example, to
discountenance it.

With regard to the introduction of a figurative and ornamental
style into memoirs purely scientific, no one could entertain a more
decided objection; and in his "Last Days," he warns us against the
practice.

"In detailing the results of experiments, and in giving them to the
world, the chemical philosopher should adopt the simplest style
and manner; he will avoid all ornaments, as something injurious
to his subject, and should bear in mind the saying of the first
king of Great Britain, respecting a sermon which was excellent in
doctrine, but overcharged with poetical allusions and figurative
language,--'that the tropes and metaphors of the speaker were like
the brilliant wild flowers in a field of corn, very pretty, but
which did very much hurt the corn.'"




CHAPTER IV.

   Davy makes a tour with Mr. Purkis, through Wales.--Beautiful
   phenomenon observed from the summit of Arran Benllyn.--Letter
   to Mr. Gilbert.--Journal of the Institution.--Davy's papers on
   Eudiometry, and other subjects.--His first communication to the
   Royal Society, on a new galvanic pile.--He is proposed as a
   Fellow, and elected into the Society.--His paper on astringent
   vegetable substances, and on their operation in tanning
   leather.--His letter to Mr. Poole.--He is appointed Chemical
   Lecturer to the Board of Agriculture.--He forms friendships
   with the Duke of Bedford, Mr. Coke, and many other celebrated
   agriculturists.--Attends the sheep-shearing at Holkham and
   Woburn.--Composes a Prologue to the "Honey-Moon."


After the fatigues and anxieties of his first session, Davy sought
relaxation and repose amidst the magnificent scenery of Wales. The
following letter will serve more fully to exhibit the enthusiasm he
experienced in contemplating Nature in her wild and simplest forms.


    TO SAMUEL PURKIS, ESQ.

    Matlock, August 15, 1802.

    MY DEAR FRIEND,

    Had I been alone, and perfectly independent as to my plans, I
    should probably have written to you long ago. I should have begged
    you to hasten your departure, so that we might have rejoiced
    together in Wales, under the influence of that moon which is now
    full in all its glory; for Derbyshire, taken as a whole, has not
    pleased me. A few beautiful valleys, placed at the distance of many
    miles from each other, do not compensate for the almost uniform
    wildness and brown barrenness of the hills and plains; and in the
    watering places, there is little amongst the _living beings_ to
    awaken deep moral feelings, or to call the nobler powers of the
    mind, which act in consequence of sympathy, into existence.

    I have longed for the mountain scenery, and for the free
    inhabitants of North Wales; and even the majestic valleys of the
    Wye and the Derwent have been to me but typical of something more
    perfect in beauty and grandeur.

    Whenever it shall seem fitting to you, I shall be prepared
    for our long contemplated journey, and do not delay your
    departure;--_before_ the 21st would be more agreeable to me than
    _after_ that period; and then we shall be able to view the horns of
    the next moon, where they are most beautiful.

    I have enquired much concerning Dove-dale, since I have been here,
    and, from the most accurate accounts, I am inclined to believe that
    it is inferior, in point of sublime scenery, to _Chee Tor_, near
    Bakewell, and in beauty, to the valley of the _Great Tor_, in which
    I am now writing. On the whole, I think your best plan will be to
    meet me at Matlock, which you must see, and then, in our route to
    Buxton, we can visit the valley of the Wye, and the most noble
    _Chee Tor_.

    Concerning the excursion of Dove-dale, I am undecided, and it
    shall depend upon you to determine with regard to it.

    As one great object in our excursions is to view Nature and man
    in their most simple forms, and to gain a temporary life of new
    impressions, I submit to you whether it will not be best to steer
    clear of _towns_, _cities_, and _civilized society_, in which, for
    the most part, we can see what we have only seen before.

    If we visit Sir Joseph Banks, it certainly should be only _en
    passant_: and to see that most excellent personage, and to be
    obliged to quit him immediately, will be at least painful; for the
    respectful feelings he produces in the mind are always modified by
    affection.

    I have no room to give you the quantity of information that I
    have gained concerning the places and people of Wales; this shall
    serve for our Derbyshire chat. I thank you much for your last kind
    letter, which gave me high pleasure. You possess the true spirit of
    composition, which embodies facts in words.

    I am, &c.
    H. DAVY.


I am informed by Mr. Purkis, that in the latter end of this summer,
he made a pedestrian tour with Davy, through North and South
Wales, and he has transmitted to me the following account of this
excursion.--"We visited every place possessing any remains of
antiquity, any curious productions of nature or art, and every spot
distinguished by romantic and picturesque scenery. Our friend's
diversified talents, with his knowledge of Geology, and Natural
History in general, rendered him a most delightful companion in a
tour of this description. Every mountain we beheld, and every river
we crossed, afforded a fruitful theme for his scientific remarks.
The form and position of the mountain, with the several _strata_
of which it was composed, always procured for me information as
to its character and classification; and every bridge we crossed
invariably occasioned a temporary halt, with some appropriate
observations on the productions of the river, and on the diversion
of angling.

"In one of our morning excursions in North Wales, we ascended the
summit of _Arran Benllyn_, a celebrated mountain, inferior only to
Snowdon and Cader Idris, a few miles from the lake of Bala. Here
we were fortunate in beholding a scene of extraordinary sublimity,
seldom witnessed in this climate. From the top of this mountain
we looked down, about mid-day, on a deep valley eight or ten
miles in length, and as many in breadth, the whole of which, for
a considerable height from the surface of the ground, was filled
with beautiful clouds, while the atmosphere around the summit on
which we stood was perfectly clear, and the sky above us of a deep
blue colour. The clouds in the valley were in irregular, gentle
undulations, dense, compact, and continuous, of that kind which is
denominated by Meteorologists _cirro-cumulus_, and by the vulgar,
_woolpack_ clouds, such as are often seen in the higher regions
on a fine summer's day. The sun shone with great brilliancy, and
illumined their various forms with silver, grey and blue tints of
exquisite beauty. As there was scarcely a breath of air stirring
below the mountain, this aggregation of clouds, probably occasioned
by some electrical agency, remained fixed and stationary, as
if identified with the valley. The higher parts of most of the
surrounding hills were enveloped in mist, above which the tops
of _Snowdon_ and _Cader Idris_ towered distinctly visible, and
appeared like small islands rising out of the sea. This scene
altogether was one of inexpressible magnificence and grandeur,
filling the mind with awe and rapture. We seemed to feel ourselves
like beings of a higher order in a celestial region, looking down
on the lower world with conscious superiority.

"After sitting and ruminating on this sublime spectacle for two or
three hours, we left the summit of the mountain with reluctance,
and, slowly descending, rested at intervals, and often cast a
longing, lingering look behind.

"On reaching our comfortable inn at Bala, while waiting for dinner,
Davy walked about the room, and, as if by inspiration, broke out
in a beautiful impassioned apostrophe on the striking scene we
had so recently witnessed. It was in a kind of unmeasured blank
verse, highly animated and descriptive, at once poetical and
philosophical. At the conclusion of this eloquent effusion, I
endeavoured to recollect and commit it to writing, but I could not
succeed, and Davy was too modest to assist my memory.

"In a tour through North Wales, where the few small inns have
seldom any spare rooms, different parties are often obliged to sit
in the same apartment, and to eat at the same table. Hence we were
occasionally introduced to characters of various descriptions,
some of whom gratified us by their agreeable qualities, while
others disgusted us by their ignorance and impertinence. On one
occasion, after a heavy shower of rain in the middle of August, we
were drying our clothes by the fire in the little Inn at _Tan y
Bwlch_, when the landlord requested us to admit a gentleman, who
was very wet. A young man, of pleasing appearance and manner, was
then introduced, and after some common-place observations, we sat
down to dinner. The stranger was evidently a man of education and
acquirements, and after the cloth had been removed, he began to
discourse very fluently on scientific subjects. He talked of oxygen
and hydrogen, of hornblende, and the _Grawacké_ of Werner, and
geologists, in the most familiar tone of self-complacency.

"Davy's youth, simplicity of manner, and cautious concealment
of superior knowledge, not exciting constraint, our companion
was naturally induced to deliver his opinions with the utmost
freedom and confidence on all subjects. We commenced on poetry and
painting; the sublime and beautiful; then proceeded to mineralogy,
astronomy, &c. and occasionally digressed on topics of mirth and
humour, so that the evening was passed with general satisfaction.

"When Davy had retired to rest, and I was left alone with our
companion, I enquired how he liked my friend, and whether he
considered him a proficient in science, and versed in chemistry
and geology? He answered coolly, that 'he appeared to be rather
a clever young man, with some general scientific knowledge.' He
then asked his name, and when I announced 'Davy, of the Royal
Institution,' the stranger seemed thunderstruck, and exclaimed,
'Good God! was that really Davy? How have I exposed my ignorance
and presumption!' It is scarcely necessary to add, that at the
breakfast table the next morning, he talked on subjects of science
with less volubility than on the preceding evening."

After Davy's return from this expedition, he wrote the following
letter.


    TO DAVIES GIDDY, ESQ.

    Royal Institution, Oct. 26, 1802.

    MY DEAR SIR,

    It is long since I have had the pleasure of hearing from you.
    You probably received a hasty letter that I wrote to you in the
    beginning of the summer. Since that period, I have been idling away
    much of my time in Derbyshire and North Wales.

    Till very lately, I had hopes of being able to spend a few weeks
    of the autumn in Cornwall, but I now find that it will not suit
    with my occupations. Not having it in my power to see you, you may
    believe that I am most anxious to hear from you.

    We hear, at this time, in London of comparatively few scientific
    novelties. The wonders of revolutionized Paris occupy many of our
    scientific men; and the summer and autumn are not the working
    seasons in great cities. The rich and fashionable part of the
    community think it their duty to kill time in the country, and
    even philosophers are more or less influenced by the spirit of the
    times.

    In the last volume of the Manchester Memoirs, _i.e._ the fifth, are
    some papers of Mr. Dalton on the Constitution of the Atmosphere;
    on the expansive powers of Steam; and on the dilatation of Elastic
    Fluids by Heat. As far as I can understand his subjects, the author
    appears to me to have executed them in a very masterly way. I wish
    very much to have your judgment upon his opinions, some of which
    are new and very singular.

    Have you yet seen the theory of my colleague, Dr. Young, on the
    undulations of an Ethereal Medium as the cause of Light? It is not
    likely to be a popular hypothesis, after what has been said by
    Newton concerning it. He would be very much flattered if you could
    offer any observations upon it, whether for or against it. The
    paper is in the last volume of the Transactions.

    I believe I mentioned to you in a former letter that _Terra
    Japonica_, or _Extractum Catechu_, contained a very large
    proportion of the tanning principle. My friend Mr. Purkis, an
    excellent practical tanner, has lately tried some experiments upon
    it in the large way. It answers very well, and I am now wearing
    a pair of shoes, the leather of one of which was tanned with
    oak-bark, and that of the other with _Terra Japonica_; and they
    appear to be equally good. We are in great hopes that the East
    India Company will consent to the importation of this article. One
    pound of it goes at least as far as nine pounds of oak-bark; and it
    could certainly be rendered in England for less than four-pence
    the pound: oak-bark is nearly one penny per pound.

    The _Zoonic acid_, which M. Berthollet supposed to be a peculiar
    acid, has been lately shown by M. Thénard to be only acetous acid,
    holding a peculiar animal matter in solution.

    Gregory Watt is just returned from the Continent, where he has
    passed the last fifteen months. He has been much delighted with his
    excursion, but his health is at present bad. I trust, however, that
    English roast-beef and English customs will speedily restore it.

    We are publishing, at the Royal Institution, a Journal of Science,
    which contains chiefly abridged accounts of what is going on in
    different parts of Europe, with some original papers; and in hopes
    that its diffusion may become more general, we have fixed its price
    at one shilling. As soon as I have an opportunity, I will send you
    the last numbers of it.

    I am beginning to think of my Course of Lectures for the winter. In
    addition to the common course of the Institution, I have to deliver
    a few lectures on Vegetable Substances, and on the connection
    of Chemistry with Vegetable Physiology, before the Board of
    Agriculture. I have begun some experiments on the powers of soils
    to absorb moisture, as connected with their fertility. I have, for
    this purpose, made a small collection of those of the _calcareous_
    and _secondary_ countries, and I wish very much for some specimens
    from the _granitic_ and _schistose_ hills of Cornwall. If you
    could, without much trouble, cause to be procured from your
    estates different pieces of uncultivated soil, of about a pound
    weight each, I should feel much obliged to you. They should be
    accompanied by specimens of the stone or strata on which they lie.

    I am, dear Sir, with affection and respect, yours,

    H. DAVY.


Of the Journals alluded to in the above letter, it would seem that
Davy and Dr. Young were the joint editors. The former appears both
as a reviewer and an original writer, and in each capacity we
recognise the peculiarities of his genius: in the one case, by the
quickness with which he detects error; and in the other, by the
avidity with which he apprehends truth.

It will not be uninteresting to take a short review of his original
communications, especially as the work has become extremely scarce;
indeed, as it was published in numbers, it is very probable that
only a few copies have escaped the common fate of periodicals.

His first paper is entitled, "An Account of a New Eudiometer," and
has for its principal object the recommendation of the solution of
the green muriate, or sulphate of iron, impregnated with _nitrous_
gas; the knowledge of the properties of which, in absorbing oxygen
gas, arose out of those experiments to which an allusion has been
already made.[40]

  [40] See page 88.

This test is prepared by transmitting a current of nitrous
gas through a saturated solution of the salt of iron. As the
absorption of the gas proceeds, the solution acquires the colour
of a deep olive brown; and when the impregnation is completed,
it appears opaque and almost black. The process is apparently
owing to a simple elective attraction; in no case is the gas
decomposed; and under the exhausted receiver it resumes its elastic
form, leaving the fluid with which it was combined, unaltered in
its properties. The test, therefore, can only be regarded as a
convenient modification of that of Priestley, in which the nitrous
gas was presented to the atmospheric air to be examined, without
the intervention of any third body.

The only apparatus required for the application of the test, as
suggested by Davy, is a small graduated tube, having its capacity
divided into one hundred parts, and a vessel for containing the
fluid. The tube, after being filled with the air to be examined, is
introduced into the solution, and shaken in contact with it; when
the air will be rapidly diminished in volume, and the whole of its
oxygen, in a few minutes, condensed into nitrous acid.

By means of this test, Davy informs us that he examined the
atmosphere in different places, without being able to ascertain any
notable difference in the proportions of its component parts.

Twenty-eight years have elapsed since the publication of this
paper; and yet, amidst the rapid progress of discovery, Eudiometry
has not been able even to modify the results it has given us; but
the reader will be pleased to remember, that by these tests it is
only professed to show the relative proportions of oxygen in air;
the salubrity of an atmosphere depends upon many other causes,
especially its condition with regard to moisture, which, in a
variety of ways, exerts an influence upon the structures of the
body.

In this Journal we also find several original communications from
Davy on galvanic phenomena, which will be noticed on a future
occasion. There is likewise a paper of considerable interest,
entitled, "An Account of a method of copying Paintings upon Glass,
and of making Profiles, by the agency of Light upon Nitrate of
Silver, invented by T. Wedgwood, Esq.: with Observations by H.
Davy."

In the first place, he gives an account of the experiments of Mr.
Wedgwood, and then, with his usual sagacity, extends our knowledge
of the subject by his own researches.

Chemists had been long acquainted with the fact, that white paper,
or white leather, moistened with a solution of the _nitrate of
silver_, although it does not undergo any change when kept in
a dark place, will speedily change colour on being exposed to
daylight; and that, after passing through different shades of grey
and brown, it will at length become nearly black. These alterations
in colour take place more speedily in proportion as the light is
more intense. In the direct beams of the sun, two or three minutes
are sufficient,--in the shade, several hours are required, to
produce the full effect; and light transmitted through differently
coloured glass, acts upon it with different degrees of intensity.
It is found, for instance, that red rays, or the common sunbeams
passed through red glass, have very little action upon it; yellow
and green are more efficacious; but blue and violet produce the
most decided and powerful effects. Davy observes that these facts
were analogous to those which were long ago observed by Scheele,
and confirmed by Senebier.

To Mr. Wedgwood, however, belongs the merit of having first applied
them for the ingenious purpose of copying engravings, &c. His first
attempt was to copy the images formed by the _camera obscura_; but
they were found to be too faint to produce, in any moderate time,
the necessary changes upon the _nitrate of silver_. With paintings
on glass he was more successful; for the copying of which, the
solution should be applied on leather, which is more readily acted
upon than paper. When a surface thus prepared is placed behind a
painting on glass, exposed to the solar light, the rays transmitted
through the differently coloured surfaces produce distinct tints of
brown or black, sensibly differing in intensity, according to the
shades of the picture; and where the light is unaltered, the colour
of the _nitrate_ becomes deepest.

Besides this application of the method of copying, there are many
others. It may be rendered subservient for making delineations of
all such objects as are possessed of a texture partly opaque, and
partly transparent; such, for instance, as the woody fibres of
leaves, and the wings of insects; for which purpose, it is only
necessary to cause the direct solar light to pass through them, and
to receive the shadows upon prepared leather.

To Davy we are indebted for an extremely beautiful application
of this principle,--that of copying small objects produced by
means of the solar microscope. For the success, however, of this
experiment, it is necessary that the prepared leather should be
placed at a small distance only from the lens.

The copy of a painting, or the profile of an object, thus obtained,
must of course be preserved in an obscure place; for all the
attempts that have been made to prevent the uncoloured parts
of the copy from being acted upon by light, have hitherto been
unsuccessful. They have been covered with a thin coating of fine
varnish; and they have been submitted to frequent washings; yet,
even after this latter operation, it would seem that a sufficient
quantity of the active matter will still adhere to the white parts
of the surface, and cause them to become dark on exposure to the
rays of the sun. From this circumstance, Davy thinks it probable
that a portion of the metallic oxide abandons its acid, to enter
into union with the animal or vegetable substance, so as to form
with it an insoluble compound.

It will be remembered that Davy had made some early experiments on
the collision of flint and steel _in vacuo_:[41] we find in the
Royal Institution Journal a farther investigation of the subject;
when he admits that, although sparks are not produced under these
circumstances, yet that a faint light becomes visible. In many
instances, he refers the phenomenon to electricity excited by
friction, more especially in the instances of glass, quartz, sugar,
&c. which give out light when rubbed. In other cases, he considers
it probable that a species of phosphorescence may be occasioned
by the heat; and he thinks that there may occasionally take place
an actual ignition of abraded particles, in consequence of their
imperfect conducting power: a supposition which he thinks receives
strong support from an experiment of Mr. Wedgwood, who found that a
piece of window-glass, when brought into contact with a revolving
wheel of grit, became red hot at its point of friction, and gave
off luminous particles that were capable of inflaming gunpowder and
hydrogen gas.

  [41] See page 67.

We shall also find in this volume an account of some observations
which he made upon the motions of small pieces of _acetate of
potash_, during their solution, upon the surface of water. After
the interesting and extraordinary observations of Mr. Brown, every
phenomenon of this kind is calculated to excite attention.

Davy states that the fragments were agitated by very singular
motions during the time of their solution, sometimes revolving for
a second or two, and then moving rapidly backwards and forwards
in various directions. He considers the phenomenon as evidently
connected with the rapid process of solution, since the motions
became weaker as the point of saturation approached. The thinnest
film of oil, or of ether, wholly destroyed the effect. Those pieces
which were most irregular in their forms underwent, by far, the
most rapid motions; from which, he thinks, it would appear, that
the phenomenon was in some measure owing to changes in the centre
of gravity of the particles during their solution. The projectile
motions, however, would seem to depend upon the continual descent
of a current of the saline solution from the agitated particle,
in consequence of which, the surrounding water would press upon
different parts of it with different degrees of force. Besides
which, an increase of temperature, which was found to accompany the
solution of the salt, might in a degree modify the effect.

His first communication to the Royal Society was entitled "An
Account of some Galvanic Combinations, formed by an arrangement
of single metallic plates and fluids, analogous to the Galvanic
Apparatus of M. Volta."

It was read on the 18th of June 1801, and will be examined in a
future part of these memoirs.

The certificate, recommending him as a candidate for the honour
of a seat in the Royal Society, was read for the first time on
the 21st of April 1803; and having been duly suspended in the
meeting-room, during ten sittings of the Society, according to
the statute, he was put to the ballot, and elected on the 17th of
November in the same year.

As every circumstance connected with the progress of Davy will be
hereafter viewed with considerable interest, I shall here introduce
the form of the certificate, and record the names of those Fellows
who sanctioned it by their signatures.


    "HUMPHRY DAVY, ESQ. Professor of Chemistry in the Royal Institution
    of Great Britain, a gentleman of very considerable scientific
    knowledge, and author of a paper in the Philosophical Transactions,
    being desirous of becoming a Fellow of the Royal Society, we
    the undersigned do from our personal knowledge recommend him
    as deserving that honour, and as likely to prove an useful and
    valuable member.

    (Signed) MORTON,
             R. J. SULLIVAN,
             KINNAIRD,
             CHARLES HATCHETT,
             THOMAS YOUNG,
             WEBB SEYMOUR,
             W. G. MATON,
             THOMAS RACKETT,
             JAMES EDWARD SMITH,
             W. G. JORDAN,
             JOHN WALKER,
             RICHARD CHENEVIX,
             ALEXANDER CRICHTON,
             HENRY C. ENGLEFIELD,
             CHARLES WILKINS,
             GIFFIN WILSON,
             GILBERT BLANE,
             EDWARD FORSTER."


On the 7th of July, in the same year, he was elected an Honorary
Member of the Dublin Society, having been proposed from the chair
by the Vice-President, General Vallancey.

It has been stated that, shortly after Davy's arrival at the
Institution, the Managers, being anxious to encourage all
investigations of a practical tendency, directed him to deliver
a series of lectures on the art of tanning. With this view, he
entered into a scientific examination of the subject, in which he
was encouraged by Sir Joseph Banks, the liberal patron and promoter
of all useful knowledge, who supplied him with various materials
for experiment.

The subject had recently attracted considerable attention, both at
home and abroad, but much still remained to be effected; and Davy
succeeded in adding many important facts to the general store.

In the Royal Institution Journal already noticed, we find several
communications from him, under the titles of "Observations on
different methods of obtaining Gallic Acid;"--"On the processes
of Tanning," &c. All the new facts however, discovered in the
course of his experiments, were embodied in a long and elaborate
memoir, which was read before the Royal Society on the 24th of
February 1803, and published in the Philosophical Transactions
for that year. It was entitled "An Account of some Experiments
and Observations on the constituent parts of certain astringent
Vegetables, and on their operation in Tanning. By Humphry Davy,
Professor of Chemistry in the Royal Institution. Communicated by
the Right Honourable Sir Joseph Banks, P. R. S."

Although Seguin and Proust had already examined many of the
properties of that vegetable principle to which the name of
_tannin_ had been given, yet its affinities had been but little
examined; and the manner in which its action upon animal matters
may be modified by combination with other substances, had been
still less considered.

His principal design in this enquiry was to elucidate the practical
part of the art of tanning skins, so as to form leather; but
in pursuing this object, he was necessarily led into chemical
investigations connected with the analysis of the various bodies
containing the tanning principle, and the peculiar properties and
value of each.

The vegetable principles that had been regarded as more usually
present in astringent infusions, are _tannin_, _gallic acid_,
and _extractive matter_. In attempting to ascertain the relative
proportions of _tannin_ contained in different infusions, Davy was
led, after various trials, to prefer the generally received method
of precipitating by means of _gelatine_ procured from isinglass. In
using this test, however, he discovered that several precautions
were necessary;--that the solution should be quite fresh,--that
it should be as much saturated as may be compatible with its
fluidity,--and that the precipitate obtained should be reduced to a
uniform degree of dryness.

It is evident that if the quantity of gelatine in the solution,
employed as the precipitant, be known, it will only be necessary to
ascertain the weight of the precipitate produced by it, in order to
learn the absolute proportion of tannin present in any specimen.

He next directed his attention to the discovery of some method
by which the _gallic acid_ might be separated from _extractive
matter_, in cases where they exist in combination, but the enquiry
was not successful; for, as he observes, it is difficult to render
the _extractive_ insoluble, so as to separate it, without at the
same time decomposing the gallic acid. It is true that æther will
dissolve the latter, without exerting much action upon the former;
but then, he adds, whenever the gallic acid is in large quantities,
this method will fail, "in consequence of that _affinity_ which is
connected with mass." Here then he adopts that celebrated theory of
Berthollet,[42] which he afterwards so vigorously and successfully
attacked.[43]

  [42] Récherches sur les Lois de l'Affinité.--Mém. de l'Institut
  National, Tome III. p. 5.

  [43] The masterly manner in which he combated the successive
  arguments of Berthollet upon this question is admirable. In the
  first place, he attacked the theory upon general principles, and
  then exposed the fallacy of the several experiments adduced in
  its support. "Were the proposition correct, that _in all cases
  of decomposition in which two bodies act upon a third, that
  third is divided between them in proportion to their relative
  affinities, and their quantities of matter_, it is quite evident
  that there could be scarcely any definite proportions: a salt
  crystallizing in a strong alkaline solution would be strongly
  alkaline; in a weak one, less alkaline; and in an acid solution
  it would be acid." With regard to glasses and alloys, adduced
  by M. Berthollet as compounds of indefinite proportions, Davy
  answers--"It is not easy to prove, in such cases, that the
  elements are chemically combined, for the points of fusion of
  alkali, glass, and certain metallic oxides, are so near to each
  other, that transparent mixtures of them may be formed." The
  experiment upon which M. Berthollet laid great stress, viz.
  that a large quantity of potash will separate a small quantity
  of sulphuric acid from sulphate of baryta, Davy invalidates in
  a most complete manner. He says--"This experiment was made in
  contact with the atmosphere, in which carbonic acid is always
  present; and carbonate of potash and sulphate of baryta mutually
  decompose each other."

As general tests of the respective quantities of these two
principles (gallic acid and extractive matter), he employed the
solutions of the salts of alumina and those of the peroxidated
salts of iron. The former of these precipitates _extractive_,
without materially acting upon _gallic acid_, which is thrown down
by the latter: the greatest care, however, must be taken not to add
the iron in excess, as in that case the black precipitate formed
will be redissolved, and an olive-coloured and clear fluid be only
obtained.

He details the results of a number of experiments made upon galls,
and ascertains the relative proportions of their several elements;
and he proves that tannin may exist in such a state of combination
in different substances as to elude the test of gelatine; in which
case, to detect its presence, it is necessary to have recourse to
the action of the diluted acids.

Sir Joseph Banks had concluded, from the sensible properties of
_catechu_,[44] or _terra Japonica_, that it was rich in tannin:
Davy confirmed this opinion by experiment. The leather tanned by
it appeared to possess the same qualities as when tanned in the
usual manner; and although this substance contains a small portion
of extractive matter, yet the increase of weight of the skin was
rather less than when solutions of galls were used.

  [44] Catechu is an extract obtained from the wood of a species
  of the _Mimosa_ that grows in India, by boiling and subsequent
  evaporation. It is of two kinds; one from Bengal, the other from
  Bombay. The former contains rather less, the latter rather more,
  than half its weight of tannin. The remainder in both cases is a
  peculiar extractive matter mixed with mucilage.--P.

In examining different barks, he was not able to procure from them
any free gallic acid, but their infusions gave, on evaporation,
tannin and extractive. The greater number of his experiments were
made on the barks of the oak, the Leicester willow, the Spanish
chestnut, the elm, and the common willow. The largest quantity of
tannin he found to be contained in the interior, or white cortical
layers; and the largest quantity of extractive matter in the
exterior layers; the epidermis, or rough outward bark, did not
contain either the one or the other.

From his general observations he is inclined to suppose that, in
all the astringent vegetables, the tannin is of the same species,
and that all the differences attributed to it depend upon its state
of combination with other principles.

In applying the results of his experiments to the theory of
tanning, he considers the process as simply depending upon the
union of the tannin with the matter of the skin, in such a manner
as to form with it an insoluble compound. Gallic acid, he feels
assured, does not produce any notable effects in the process; but
he thinks that the quality of the leather depends, in some degree,
upon the quantity of extractive matter it may imbibe.

Skin, combined with extractive matter only, would be increased in
weight, become coloured, and be extremely flexible, but it would
not be insoluble in water; and were it combined with tannin alone,
it would be heavier and less supple than when both these principles
enter into the compound.

He examines with great acuteness and precision some of the more
popular opinions entertained by tanners, and brings his science to
bear very satisfactorily upon several of their processes.

The grand secret, on which the profit of the trade mainly depends,
is to give the hides the greatest increase of weight in the least
possible time. To effect this, various schemes have been proposed,
many of which, from the ignorance of the operators, instead of
promoting, have defeated the object. Different _menstrua_ have been
suggested for expediting the process, and amongst them lime-water
and the solutions of pearl-ash; but, as he has clearly shown,
these two substances form compounds with tannin which are not
decomposable by gelatine; whence it follows that their effects must
be pernicious; and there is very little reason to suppose that any
bodies will be found which, at the same time that they increase
the solubility of tannin in water, will not likewise diminish its
attraction for skin.

His experiments having proved that the saturated infusions of
astringent barks contain much less extractive matter, in proportion
to their tannin, than those which are weaker, it follows, that by
quickly tanning the skin, we render the leather less durable. These
observations show that there is some foundation for the vulgar
opinion of workmen, concerning what is technically called the
_feeding_ of leather in the slow method of tanning.

Such is an outline of this interesting paper, in which the author
has displayed the talent so characteristic of his mind--that of
bringing science and art into useful alliance with each other.
It forms, at this day, the guide of the tanner; and those who
previously carried on the process by a routine of operations, of
which they knew not the reasons, are now capable of modifying it,
without the risk of spoiling the result. Many of those expedients
which have been brought forward as novelties in later years, may
be found in this paper; or, at least, have arisen out of the
principles disclosed during his investigations.

It has been stated that, shortly after Davy's successful _début_
as a lecturer, his manners underwent a change, and that, to the
regret of his friends, he lost much of his native simplicity. On
the 5th of February 1802, he had dined with Sir Harry Englefield
at his house at Blackheath; and eighteen years afterwards, the
worthy Baronet alluded to his interesting demeanour upon that
occasion, in terms sufficiently expressive of his feelings--"It was
the last flash of expiring Nature." It was natural that his best
friends, on perceiving this change of manner, should entertain some
apprehensions as to the deeper qualities of his heart. Mr. Purkis
has placed in my hands the following letter addressed to him by Mr.
Coleridge; it will interest the reader by the force and truth with
which its talented writer characterises the perils which beset the
elevated path of the young philosopher at the commencement of his
career.


    TO SAMUEL PURKIS, ESQ.

    Nether Stowey, Feb. 17, 1803.

    MY DEAR PURKIS,

    I received your parcel last night, by post, from Gunville, whither
    (crossly enough) I am going with our friend Poole to-morrow
    morning. I do from my very heart thank you for your prompt and
    friendly exertion, and for your truly interesting letter. I shall
    write to Wedgwood by this post; he is still at Cote, near Bristol;
    but I shall take the _Bang_ back with me to Gunville, as Wedgwood
    will assuredly be there in the course of ten days. Jos. Wedgwood is
    named the Sheriff of the County. When I have heard from Wedgwood,
    or when he has tried this _Nepenthe_, I will write to you. I have
    been here nearly a fortnight; and in better health than usual.
    Tranquillity, warm rooms, and a dear old friend, are specifics for
    my complaints. Poole is indeed a very, very good man. I like even
    his incorrigibility in small faults and deficiencies: it looks
    like a wise determination of Nature to let well alone; and is a
    consequence, a necessary one perhaps, of his immutability in his
    important good qualities. His journal, with his own comments, has
    proved not only entertaining but highly instructive to me.

    I rejoice in Davy's progress. There are three Suns recorded in
    Scripture:--Joshua's, that stood still; Hezekiah's, that went
    backward; and David's, that went forth and hastened on his course,
    like a bridegroom from his chamber. May our friend's prove the
    latter! It is a melancholy thing to see a man, like the Sun in the
    close of the Lapland summer, meridional in his horizon; or like
    wheat in a rainy season, that shoots up well in the stalk, but does
    not _kern_. As I have hoped, and do hope, more proudly of Davy than
    of any other man; and as he has been endeared to me more than any
    other man, by the being a Thing of Hope to me (more, far more than
    myself to my own self in my most genial moments,)--so of course my
    disappointment would be proportionally severe. It were falsehood,
    if I said that I think his present situation most calculated,
    of all others, to foster either his genius, or the clearness
    and incorruptness of his opinions and moral feelings. I see two
    Serpents at the cradle of his genius, Dissipation with a perpetual
    increase of acquaintances, and the constant presence of Inferiors
    and Devotees, with that too great facility of attaining admiration,
    which degrades Ambition into Vanity--but the Hercules will strangle
    both the reptile monsters. I have thought it possible to exert
    talents with perseverance, and to attain true greatness wholly
    pure, even from the impulses of ambition; but on this subject Davy
    and I always differed.

    When you used the word "gigantic," you meant, no doubt, to give
    me a specimen of the irony I must expect from my Philo-Lockian
    critics. I trust, that I shall steer clear of almost all offence.
    My book is not, strictly speaking, metaphysical, but historical.
    It perhaps will merit the title of a History of Metaphysics in
    England from Lord Bacon to Mr. Hume, inclusive. I confine myself
    to facts in every part of the work, excepting that which treats of
    Mr. Hume:--_him_ I have assuredly besprinkled copiously from the
    fountains of Bitterness and Contempt. As to this, and the other
    works which you have mentioned, "have patience, Lord! and I will
    pay thee all!"

    Mr. T. Wedgwood goes to Italy in the first days of May. Whether I
    accompany him is uncertain. He is apprehensive that my health may
    incapacitate me. If I do not go with him, (and I shall be certain,
    one way or the other, in a few weeks,) I shall go by myself, in the
    first week of April, if possible.

    Poole's kindest remembrances I send you on my own hazard; for he
    is busy below, and I must fold up my letter. Whether I remain in
    England or am abroad, I will occasionally write you; and am ever,
    my dear Purkis, with affectionate esteem,

    Your's sincerely,
    S. T. COLERIDGE.


Remember me kindly to Mrs. Purkis and your children. T. Wedgwood's
disease is not painful: it is a complete _tædium vitæ_; nothing
pleases long, and novelty itself begins to cease to act like
novelty. Life and all its forms move, in his diseased moments, like
shadows before him, cold, colourless, and unsubstantial.

From the tone of the following letter, it may be presumed also,
that Mr. Poole, to whom it is addressed, had expressed some anxiety
upon the dangers to which his flattering station exposed him.


    TO THOMAS POOLE, ESQ.

    London, May 1, 1803.

    MY DEAR POOLE,

    Have you no thoughts of coming to London? I have always recollected
    the short periods that you have spent in town, with a kind of mixed
    feeling of pleasure and regret.

    In the bustling activity occasioned in cities by the action and
    re-action of diversified talents, occupations, and passions, our
    existence is, as it were, broken into fragments, and with you I
    have always wished for unbroken intercourse and continuous feeling.

       *       *       *       *       *

    Be not alarmed, my dear friend, as to the effect of worldly society
    on my mind. The age of danger has passed away. There are in the
    intellectual being of all men, permanent elements, certain habits
    and passions that cannot change. I am a lover of Nature, with an
    ungratified imagination. I shall continue to search for untasted
    charms,--for hidden beauties.

    My _real_, my _waking_ existence is amongst the objects of
    scientific research: common amusements and enjoyments are necessary
    to me only as dreams, to interrupt the flow of thoughts too nearly
    analogous to enlighten and to vivify.

    Coleridge has left London for Keswick; during his stay in town, I
    saw him seldomer than usual; when I did see him, it was generally
    in the midst of large companies, where he is the image of power and
    activity. His eloquence is unimpaired; perhaps it is softer and
    stronger. His will is probably less than ever commensurate with
    his ability. Brilliant images of greatness float upon his mind:
    like the images of the morning clouds upon the waters, their forms
    are changed by the motion of the waves, they are agitated by every
    breeze, and modified by every sunbeam. He talked in the course of
    one hour, of beginning three works, and he recited the poem of
    Christobel unfinished, and as I had before heard it. What talent
    does he not waste in forming visions, sublime, but unconnected with
    the real world! I have looked to his efforts, as to the efforts of
    a creating being; but as yet, he has not even laid the foundation
    for the new world of intellectual forms.

    When my Agricultural Lectures are finished, I propose to visit
    Paris, and perhaps Geneva. How I regret that circumstances had not
    enabled us to make the same tour at the same time! I think, at
    all events, I shall see you before the Autumn, on your own lands,
    amidst your own images and creations.

    Your affectionate friend,

    HUMPHRY DAVY.


    TO THE SAME.

    Royal Institution.

    MY DEAR POOLE,

    Often, very often, in the midst of the tumults of the multitude in
    this great city, has my spirit turned in quietness and solitude
    towards you.

    I hope soon to see you in Somersetshire, where we may worship
    Nature, and the spirit that dwells in Nature, in your green fields
    and under your tranquil sky. My communications with you and
    Coleridge and Southey, and other ornaments of the great existing
    Being, have excited feelings which cheer me in the apathy of
    London, and which make me love human nature.

       *       *       *       *       *

    Your account of the young man who murdered his wife, I read with
    deep interest. It is from such narratives of the conduct of common
    persons, that the laws of simple human nature must be deduced.
    Beings acted on by few objects, awakening in them few but deep
    passions, are the beings which Metaphysicians and Moralists ought
    to study; not those who exist in general life, having their
    energies and feelings so attached to multiplied and indefinite
    things--so mixed up and connected with myriads of circumstances, as
    to be imperceptible, unless by a microscopic moral eye.

    I am, &c. &c.

    H. DAVY.


From the former letter, we learn that Davy, at this period,
proposed delivering some lectures on the Chemistry of Agriculture.
From the memorandums of my late friend Mr. Arthur Young, the
celebrated Secretary to the Board of Agriculture, I have succeeded,
through the kindness of his daughter, in procuring the following
extracts; the only source from which I have been able to obtain any
correct information upon this point in his scientific life.--"May
15th, 1803. _Mem._ Two lectures by Mr. Davy have taken place, and
been very well attended; they intend retaining him by a salary of
a hundred pounds a year,--a very good plan."

Amongst the pamphlets at Bradfield Hall is a small quarto of
fourteen pages, entitled, "Outlines of a Course of Lectures on
the Chemistry of Agriculture, to be delivered before the Board
of Agriculture, 1803." It was evidently only printed for private
circulation amongst the members. At the same time, he printed a
small pamphlet, containing an explanation of the terms used in
chemistry, for the instruction of those amongst his audience who
had not particularly directed their attention to the science.

The first lecture was delivered on Tuesday, May the 10th, at twelve
at noon, and five others on the succeeding Tuesdays and Fridays.

In an address to the Board of Agriculture by Sir John Sinclair,
delivered in April 1806, in reviewing the various objects to which
the attention of the Board had been directed, he thus alludes to
the subject:--"In the year 1802, when my Lord Carrington was in the
chair, the Board resolved to direct the attention of a celebrated
lecturer, Mr. Davy, to agricultural subjects; and in the following
year, during the Presidency of Lord Sheffield, he first delivered
to the members of this Institution, a course of lectures on the
CHEMISTRY OF AGRICULTURE. The plan has succeeded to the extent
which might have been expected from the abilities of the gentleman
engaged to carry it into effect. The lectures have hitherto been
exclusively addressed to the Members of the Board; but to such a
degree of perfection have they arrived, that it is well worthy
of consideration, whether they ought not to be given to a larger
audience. If such an idea met with the approbation of the Board,
a hall might be procured for that purpose, or a special course of
lectures read in this room exclusively for strangers."

Davy would appear to have been very early impressed with
the importance of Chemistry, in its various applications to
Agriculture. Allusions are constantly made to it in his letters;
and at the conclusion of his "RESEARCHES," he glances at this
department of the chemistry of vegetation, and observes that,
"although it is immediately connected with the art upon which we
depend for subsistence, it has been but little investigated."

In his introductory lecture of 1802, he speaks more forcibly upon
the subject.

"Agriculture, to which we owe our means of subsistence, is an
art intimately connected with chemical science; for although the
common soil of the earth will produce vegetable food, yet it can
only be made to produce it in the greatest quantity, and of the
best quality, by methods of cultivation dependent upon scientific
principles.

"The knowledge of the composition of soils, of the food of
vegetables, of the modes in which their products must be treated,
so as to become fit for the nourishment of animals, is essential to
the cultivator of land; and his exertions are profitable and useful
to society, in proportion as he is more of a chemical professor.
Since indeed the truth has been understood, and since the
importance of agriculture has been generally felt, the character of
the agriculturist has become more dignified, and more refined;--no
longer a mere machine of labour, he has learned to think, and to
reason. He is aware of his usefulness to his fellow-men, and he is
become, at once, the friend of nature, and the friend of society."

His appointment, as chemical professor to the Board of Agriculture,
was accompanied with the obligation of reading lectures before its
members; which he continued to deliver every successive season for
ten years, modifying and extending their views, from time to time,
in such a manner as the progress of chemical discovery might render
necessary.

These discourses were collated, and published in the year 1813,
at the request of the President and members of the Board, and
they form the only systematic work we, at present, possess on the
subject. Its views, however, are too generally interesting to be
briefly dismissed; I shall therefore enter more fully into their
merits in a more advanced part of these memoirs.

His connexion with the Board necessarily brought him in contact
with the practical agriculturists and capitalists of the day, with
many of whom he formed friendships which lasted through life. With
Mr. Coke of Holkham he became well acquainted, and generally formed
one of the party at his annual sheep-shearing.[45] He was also a
frequent visitor at Woburn, and received from the Duke the means
by which he was enabled to submit to the test of practice various
theories which his science had suggested.

  [45] In the 40th volume of the "Annals of Agriculture," an
  account is given of the Holkham Sheep-shearing for 1803, and in
  the list of the company is the name of "Mr. Professor Davy."--At
  the meeting of 1808, he was also present, and is mentioned as the
  great chemist, whose discoveries will immortalize his name. Mr.
  Coke, in the course of his speech after dinner, alluding to the
  question of long and short dung, said, "It is the opinion of a
  friend of mine, who sits near me, Professor Davy, and upon whose
  judgment, on account of his extensive chemical as well as other
  scientific knowledge, I place the highest reliance, that the
  manure carried immediately on the field, without being disturbed,
  will have a greater effect in exciting rapid vegetation, and in
  encouraging the growth of the turnip plant, than when applied
  in the ordinary manner; for, under such circumstances, it will
  not only be more moist and alkaline, but it will be protected
  from a loss of substance, amounting very nearly to one-third of
  its original bulk." Davy afterwards, in company with the Duke of
  Bedford, Lord William Russell, Lord Thanet, Sir Joseph Banks,
  and other agriculturists, inspected several farms.--In 1812, his
  health was drunk at the Woburn Sheep-shearing by the Duke of
  Bedford; and in the following festival it was proposed by Lord
  Hardwicke.

  In the print of the "Woburn Sheep-shearing," published by
  Garrard, in 1811, No. 75 represents Davy; he is standing, in a
  listening attitude, behind Mr. Coke, who is conversing with Sir
  Joseph Banks, Sir John Sinclair, and Mr. Arthur Young.

In a letter to Mr. Gilbert, dated October 1803, he says: "I have
just quitted the coast of Sussex, where I have spent the last three
weeks with Lord Sheffield, the worthy biographer of Gibbon." In
fact, there was not a nobleman, distinguished for intellectual
superiority, who did not feel a pride in receiving him as a guest;
and he passed his vacations in the society of those exalted persons
who, in possessing rank, fortune, and talents, felt that they only
held such gifts from Providence, in trust for the welfare of their
fellow-countrymen.

We can scarcely picture to ourselves a being upon whom fortune
ever showered more favours than upon Davy, during this golden
period of his career. Independent in an honourable competence, the
product of his genius and industry; resident in the centre of all
scientific information and intelligence; every avenue of knowledge,
and every mode of observation open to his unwearied intellect, he
must have experienced a satisfaction which few philosophers have
ever before felt,--the power of pursuing experimental research to
any extent, and of commanding the immediate possession of all the
means it might require, without the least regard either to cost
or labour. What a contrast does this picture afford to that which
has been too faithfully represented as the more usual fate of the
philosopher and man of letters, and which exhibits little more than
the unavailing struggles of genius against penury! Instead of a
life consumed in fruitless expectation of patronage and reward, we
behold Davy, in the full bloom of reputation, courted by all whom
rank, talent, or station, had rendered conspicuous.

His life flowed on like a pure stream, under a sky of perpetual
sunshine,--not a gust ruffled its surface, not a cloud obscured its
brightness. In the morning, he was the sage interpreter of Nature's
laws; in the evening, he sparkled in the galaxy of fashion; and
not the least extraordinary point in the character of this great
man, was the facility with which he could cast aside the cares of
study, and enter into the trifling amusements of society.--"_Ne
otium quidem otiosum_," was the exclamation of Cicero; and it
will generally apply to the leisure of men actively engaged in
the pursuits of science; but Davy, in closing the door of his
laboratory, opened the temple of pleasure. When not otherwise
engaged, his custom was to play at billiards, frequent the theatre,
or read the last new novel. In ordinary cases, the genius of
evening dissipation is an arrant Penelope; but Davy, on returning
to his morning labours, never found that the thread had been unspun
during the interruption.

The following anecdote is well calculated to illustrate that
versatility of talent of which I have frequently spoken, as
well as the power he possessed of abstracting himself, without
detriment, from the most elaborate investigations. A friend of the
late Mr. Tobin called upon him at the Institution, and found him
deeply engaged in the laboratory; their conversation turned upon
"The Honey Moon," which was to be brought out on the following
evening.[46] No sooner had Davy heard that, although pressing
applications had been made to several of the poets of the day, a
Prologue had not yet been written, than he instantly quitted the
laboratory, and in two hours produced that which was recited on the
occasion by Mr. Bartley, and printed in the first edition of the
comedy. I insert it in this place.

  [46] "The Honey Moon" was produced at Drury Lane, on Thursday,
  the 30th of January, 1805.

    No uniformity in life is found:--
    In ev'ry scene varieties abound;
    And inconsistency still marks the plan
    Of that immortal noble being,--Man.
    As changeful as the April's morning skies,
    His feeling and his sentiments arise;
    And Nature to his wond'rous frame has given
    The mingled elements of Earth and Heaven.
    In diff'rent climes and ages, still we find
    The same events for different ends design'd:
    And the same passion diff'rent minds can move
    To thoughts of sadness or to acts of love.

      Hence Genius draws his novel copious store;
    And hence the new creations we adore:
    And hence the scenic art's undying skill
    Submits our feeling to its potent will;
    From common accidents and common themes
    Awakens rapture and poetic dreams;
    And, in the trodden path of life, pursues
    Some object clothed in Fancy's loveliest hues--
    To strengthen nature, or to chasten art,
    To mend the manners or exalt the heart.

      So thought the man whom you must judge to-night;
    And as he thought, he boldly dared to write.
    Not new the subject of his first-born rhyme;
    But one adorn'd by bards of elder time;--
    Bards with the grandest sentiments inspired--
    Bards that in rapture he has still admired;
    And tried to imitate, with ardour warm,
    And catch the spirit of their pow'rful charm.
    With loftiest zeal and anxious hope, he sought
    To bring to modern times their strength of thought;
    And, in their glowing colours, to display
    The follies and the virtues of the day.

      Whether his talents have his wish belied,
    Your judgment and your candour must decide.
    He, though your loftiest plaudits you should raise--
    He cannot thank you for the meed of praise.
    Rapture he cannot feel, nor fear, nor shame;
    Connected with his love of earthly fame,
    He is no more.--Yet may his memory live
    In all the bloom that early worth can give!
    Should you applaud, 'twould check the flowing tear
    Of those to whom his name and hopes are dear.
    But should you an unfinish'd structure find,
    As in its first and rudest forms design'd,
    As yet not perfect from the glowing mind,
    Then with a gentle voice your censure spread,
    And spare the living--spare the sacred DEAD!

Davy would appear to have frequently amused himself with writing
sonnets, and inclosing them in letters to his several friends: the
following letter will also show that he was ambitious of being
considered a poet.


    TO SAMUEL PURKIS, ESQ.

    MY DEAR PURKIS,

    I inclose the little poem,[47] on which your praise has stamped a
    higher value, I fear, than it deserves.

    If I thought that people in general would think as favourably of my
    poetical productions, I would write more verses, and would write
    them with more care; but I fear you are partial: I am very glad,
    however, that you like the little song; at some future period I
    will send you another.

    With kind remembrances, unalterably your sincere friend,

    H. DAVY.

  [47] The subject was "_Julia's Eyes_."


On examining the laboratory notes made at this period, many of
which, however, are nearly illegible from blots of ink and stains
of acid, it would appear that his researches into the composition
of mineral bodies were most extensive, and that he obtained many
new results, of which he does not seem to have availed himself
in any of his subsequent papers. To borrow a metaphor from his
favourite amusement, he treated such results as small fry, which
he returned to their native element to grow bigger, or to be again
caught by some less aspiring brother of the angle.

Had Davy, at this period of his life, been anxious to obtain
wealth,[48] such was his chemical reputation, and such the value
attached to his judgment, that, by lending his assistance to
manufacturers and projectors, he might easily have realized it; but
his aspirations were of a nobler kind--SCIENTIFIC GLORY was the
grand object for which his heart panted: by stopping to collect the
golden apples, he might have lost the race.

  [48] I am assured by one of his earliest friends, that, at this
  period, he did not appear even to have an idea of the value of
  property. Any thing not immediately necessary to him he gave
  away, and never retained a book after he had read it.




CHAPTER V.

   Sir Thomas Bernard allots Davy a piece of ground for
   Agricultural Experiments.--History of the Origin of the Royal
   Institution.--Its early labours.--Davy's Letters to Mr. Gilbert
   and to Mr. Poole.--Death of Mr. Gregory Watt.--Davy's passion
   for Fishing, with Anecdotes.--He makes a Tour in Ireland: his
   Letters on the subject.--His paper on the Analysis of the
   Wavellite.--His Memoirs on a new method of analysing Minerals
   which contain a fixed Alkali.--Reflections on the discovery of
   Galvanic Electricity.


Very shortly after Davy had arrived in London, he formed an
intimate friendship with Mr. (afterwards Sir Thomas) Bernard;
and no sooner had he directed his attention to the subject of
Philosophical Agriculture, than the worthy Baronet allotted him a
considerable piece of ground near his villa at Roehampton, where,
under his sole direction, numerous experiments were tried, many
of which proved highly successful, and afterwards served for the
illustration of various subjects in his work on AGRICULTURAL
CHEMISTRY.

Although devoted as Davy was to the pursuits of science, he entered
warmly into all political plans for improving the condition of the
people, and advancing the progress of civilization. "No one," says
his friend Mr. Poole, "was less a sectarian, if I may use the word,
in religion, politics, or in science. He regarded with benevolence
the sincere convictions of any class on the subject of belief,
however they might differ from his own. In politics, he was the
ardent friend of rational liberty. He gloried in the institutions
of his country, and was anxious to see them maintained in their
purity by timely and temperate reform." Indeed, in carefully
analysing his mind, and tracing its developement, it appears that
benevolence was one of its leading elements; the form in which
it displayed its energies varying with the varying conditions of
intelligence. In boyish life, his imagination, acting upon his
zeal for the welfare of his species, delighted, as we have seen,
in the ideas of encountering dragons, and quelling the might of
giants; but as fancy paled with the light of advancing years, and
the judgment, presented distincter appearances, the philanthropic
antipathy which had been directed to those chimeras of the nursery,
was transferred to the two great oppressions of society, and in
Superstition he saw the dragons--in Despotism, the giants that
spread mischief and misery through the world.

Some of his early manuscripts are still in existence; and I shall
here introduce a passage from one which has been lately transmitted
to me by a gentleman resident in Penzance. The most trifling
record becomes interesting, when we can trace in it the germ of a
particular opinion, or the first symptom of a quality which may
afterwards have distinguished its possessor.

"Science is as yet in her infancy; but in her infancy she has
done much for man. The discoveries hitherto so beneficial to
mankind have been generally effected by the energies of individual
minds:--what hopes may we not entertain of the rapid progress of
the happiness of man when illumination shall become general--when
the united powers of a number of scientific men shall be employed
in discovery! Every thing seems to announce the rapid advance
of this period of improvement. The time is approaching when
despotism and superstition, those enormous chains that have so
long enfettered mankind, shall be annihilated,--when liberated man
shall display the mental energies for which he was created. At that
period, nations shall know that it is their interest to cultivate
science, and that the benevolent philosophy is never separated from
the happiness of mankind."

In his published writings, we discover evidences of the same
tendency; he suffers no opportunity to escape which can enable him
to enforce his principle, and he extracts from the most common as
well as from the least probable sources, comparisons and analogies
for its illustration. The ingenuity with which this is accomplished
often surprises and delights us; the effect upon the reader is
frequently not unlike that occasioned by the flashes of wit, to
which it surely must be closely allied, if wit be correctly defined
by Johnson "a combination of dissimilar images, or the discovery
of occult resemblances in things apparently unlike." Is not this
opinion strikingly illustrated by the happy turn given to his
observations "upon the process of obtaining nitrous oxide from
nitre,"--when he says, "Thus, if the hopes which these experiments
induce us to indulge do not prove fallacious, a substance which has
heretofore been almost exclusively appropriated to the destruction
of mankind, may become, in the hands of philosophy, the means of
producing health and pleasure!"

Mr. Poole, who watched the whole of his progress from obscurity
to distinction, and enjoyed his friendship for nearly thirty
years, says, "To be useful to science and mankind was, to use his
favourite expression, the pursuit in which he gloried. He was
enthusiastically attached to science, and to men of science; and
his heart yearned to promote their interests."

That Davy, with a mind so constituted, should have formed a
strong and ardent attachment to Sir Thomas Bernard, and that this
friendship should have been reciprocally cultivated, cannot be a
matter of surprise.

I am happy in this opportunity of paying a tribute of respect to
the memory of this most excellent person, with whom I had the
pleasure of being well acquainted. His life was one continued
scheme of active benevolence; and he merits a particular notice in
these memoirs, as being one of the principal founders and patrons
of the Royal Institution. Actuated by that noble and rational
ambition which makes private pursuits subservient to public
good, he directed all the energies of his mind, the influence of
his station, and the resources of his wealth, towards promoting
societies and schemes for encouraging the virtues and industry, and
for ameliorating the condition, of the lower classes.

In the beginning of November 1796, in conjunction with the late
Bishop of Durham, Mr. Wilberforce, and Mr. Elliot, he established
the SOCIETY FOR BETTERING THE CONDITION OF THE POOR. As one of the
primary objects of the original promoters of this society was the
formation of an institution which might teach the application of
science to the advancement of the arts of life, and to the increase
of domestic comforts, a select committee was appointed from its
body, in January 1799, for the purpose of conferring with Count
Rumford on the means of carrying such a scheme into practical
effect. This committee consisted of the Earl of Winchelsea, Mr.
Wilberforce, Mr. Sullivan, the Bishop of Durham, Sir Thomas
Bernard, and some other members of the society; and in a few weeks
they completed the arrangements, circulated printed proposals,
and collected the subscriptions, which gave birth to the ROYAL
INSTITUTION OF GREAT BRITAIN, the future cradle of experimental
science, and the destined scene of Davy's glory.

In addition to the general objects of promoting the arts and
manufactures, and of advancing the taste and science of the
country, its more immediate purpose was the improvement of the
means of industry and domestic comfort among the poor.

That this benevolent design was constantly kept in sight may be
shown by the several resolutions passed at the different meetings
of the Managers, especially at that held in March 1800; when it
was resolved to appoint _fourteen_ different committees, for the
purpose of scientific investigation and improvement; amongst which
were the following:--

"For the investigation into the processes of making bread, and into
the methods of improving it.

"For enquiring into the art of preparing cheap and nutritious soups
for feeding the poor.

"For improving the construction of cottages, and cottage
fire-places, and for improving kitchen fire-places, and kitchen
utensils.

"For ascertaining, by experiment, the effects of the various
processes of cookery upon the food of cattle.

"For improving the construction of lime-kilns, and the composition
of mortar and cements," &c. &c.

So that the foundation and original arrangements of the Royal
Institution were not only calculated to extend the boundaries of
science, but to increase its applications, and to promote and
improve those arts of life on which the subsistence of all, and the
comfort and enjoyment of the great majority of mankind absolutely
depend.

At this early period of its history, the Royal Institution
presented a scene of the most animated bustle and exhilarating
activity. Persons most distinguished in the various departments
of science and art were to be seen zealously and liberally
co-operating for the promotion and diffusion of public happiness,
under the cheering beams of popular favour and exalted patronage.
It was like 'a busy ant-hill in a calm sunshine.'

I shall only add, that Sir Thomas Bernard was the original promoter
of the "School for the Indigent Blind;" of an institution for
the protection and instruction of "Climbing Boys;" of a society
for the relief of "Poor Neighbours in Distress;" of the "Cancer
Institution;" and of the "London Fever Hospital."

The philanthropic Baronet was, moreover, the founder of the
"British Institution," for promoting the Fine Arts in the United
Kingdom; and he was also the originator of the "Alfred Club."

The vast range and practical utility of these exertions were duly
appreciated by his contemporaries, who were ever ready to promote
any scheme which had received the sanction of his patronage. It is
an anecdote worthy of being preserved, that the late Sir Robert
Peel called upon him one morning, and after a general conversation
on the different philanthropic objects they had in view, said on
leaving the room, he had to request that Sir Thomas would dispose
of something for him, in any manner he thought most serviceable,
and laid on the table an enclosure. After he had left the house,
Sir Thomas was greatly surprised, on opening it, to find a
bank-note of a thousand pounds.

The active zeal of Sir T. Bernard, like every other circumstance
which exceeds the ordinary standard of our conduct, or becomes
prominent from the rarity of its occurrence, called forth the wit
as well as the admiration of his contemporaries. One of those
modern travellers who delight in astonishing their auditors by
incredible tales and marvellous anecdotes, happening to be in
company with a noble lord as much distinguished for the playfulness
of his wit as for the profundity of his learning, told the
following improbable story: that, in a sequestered part of Italy,
when pressed by hunger and fatigue, he sought refreshment and
repose in a wild dwelling in the mountains, and was agreeably
surprised at being offered a pie; but, horror of horrors! on
examining its contents he found--a human finger!--"Nothing more
probable, Sir," interrupted his Lordship; "and I well know the
person to whom that finger belonged--to Sir Thomas Bernard, Sir,
for he had a finger in every pie."

The following letters will be read in this place with interest.


    TO DAVIES GIDDY, ESQ.

    MY DEAR SIR,

    I am now on my way to Christchurch, in company with Mr. Bernard,
    who was the founder, and has been the great supporter, of the
    Society for bettering the condition of the Poor.

    In a conversation that has just passed between us, I mentioned the
    state of improvement of the Downs between Helston and Marazion, in
    consequence of grants of small portions of land to miners and other
    tenants for cultivation, many of which have, I believe, been made
    by Lord Dunstanville. Mr. Bernard expressed a desire to know what
    the effect of this plan had been on the condition of the persons
    thus raised into "property-men."

    He is accumulating facts as to the manner in which the poor have
    been most effectually benefited, and to assist his labour would
    be to assist a good and most important cause; perhaps, you will
    have the goodness to give me a statement on this subject, which of
    course shall be used as you may think proper. You may likewise have
    similar facts nearer home, on your own estates.

    I am convinced that the effects of enabling the common labourer
    to acquire property must be striking, and must often have been an
    object of your contemplation.

    In making any statement of these facts, you will probably think
    it right to mention some particular cases, with dates, names,
    and accounts of the quantities of lands, the nature of the
    improvements, &c.

    In the reports of the "Society for bettering the condition of the
    Poor," there is one made on this minute plan of Lord Winchelsea's
    grants of land to cottagers, which conveys very full and useful
    information.

    I trust to your kindness, and believe me

    Your obliged,

    H. DAVY.


The following letter was written by Davy after his return from an
excursion to that beautiful district, the north-west of the county
of Somerset.


    TO THOMAS POOLE, ESQ.

    October, 1804.

    MY DEAR POOLE,

    I RETURNED to town a little while ago, not sorry to see the great
    city of activity and life; not sorry to see it, though I had just
    spent two months in enjoying a scenery beautiful and, to me, new;
    in witnessing much hospitality and unadulterated manners, and in
    gaining much useful information.

    Mr. Bernard is writing a history of the poor. I have lived much
    with him at Roehampton since my return, and he has read to me part
    of his work, which is popularly eloquent, very intelligent, and
    full of striking and important truths; but pray say nothing of
    this, for it is likely that it will appear without his name: the
    facts will be strong, and perhaps to some people offensive.

    I have received a letter from Coleridge within the last three
    weeks: he writes from Malta, in good spirits, and, as usual, from
    the depth of his being. God bless him!--He was intended for a great
    man; I hope and trust he will, at some period, appear as such.

    I am working very hard at this moment, and I hope soon to send
    you some of the fruits of my labours. I am likewise devising some
    plans at our Institute, for the improvement of "this generation of
    vipers;" but, although I am so vain as to announce them, I will not
    be so tedious as to detail them.

    In your answer, which I hope I shall soon receive, pray give me an
    account of the situation of "Poole's Marsh," with regard to the
    _Parrot_,[49] for I have mentioned the soil in a paper to the Board
    of Agriculture, which is now in the press.

    I am, my dear Poole,

    Your truly affectionate friend,

    H. DAVY.


  [49] He alludes to a rich piece of land near the river Parrot; a
  specimen of the soil of which Mr. Poole had sent him for analysis.

In this year, Davy was deprived of one of his earliest and most
attached friends, after a lingering illness, during which his
symptoms, by the alternations which characterise consumption,
had inspired his friends with hope, only to chill them with
despondency;--Gregory Watt terminated his earthly career.[50]

  [50] Gregory Watt was one of those philosophers to whose memory
  justice has not awarded its due. He was a meteor, whose light
  no sooner flashed upon us than it expired. His paper upon
  the gradual refrigeration of Basalt, alone entitled him to a
  distinguished rank amongst experimentalists. It was read before
  the Royal Society in May; and he expired in the following October.

On the first impression which this melancholy event produced upon
his feelings, Davy wrote a letter to his friend Clayfield, from
which the following is an extract.

"I scarcely dare to write upon the subject--I would fain do what
Hamlet does, when, in awe and horror at the ghost of his father,
he attempts to call up the ludicrous feeling, but being unable to
do so, he merely employs the words which are connected with it.--I
would be gay, or I would write gaily, in alluding to the loss
we have both sustained, but I feel that it is impossible. Poor
Watt!--He ought not to have died. I could not persuade myself that
he would die; and until the very moment when I was assured of his
fate, I would not believe he was in any danger.

"His letters to me, only three or four months ago, were full of
spirit, and spoke not of any infirmity of body, but of an increased
strength of mind. Why is this in the order of Nature, that there is
such a difference in the duration and destruction of her works? If
the mere stone decays, it is to produce a soil which is capable of
nourishing the moss and the lichen; when the moss and the lichen
die and decompose, they produce a mould which becomes the bed
of life to grass, and to a more exalted species of vegetables.
Vegetables are the food of animals,--the less perfect animals of
the more perfect; but in man, the faculties and intellect are
perfected,--he rises, exists for a little while in disease and
misery, and then would seem to disappear, without an end, and
without producing any effect.

"We are deceived, my dear Clayfield, if we suppose that the human
being who has formed himself for action, but who has been unable
to act, is lost in the mass of being: there is some arrangement of
things which we can never comprehend, but in which his faculties
will be applied.

"The caterpillar, in being converted into an inert scaly mass, does
not appear to be fitting itself for an inhabitant of air, and can
have no consciousness of the brilliancy of its future being. We are
masters of the earth, but perhaps we are the slaves of some great
and unknown beings. The fly that we crush with our finger, or feed
with our viands, has no knowledge of man, and no consciousness of
his superiority. We suppose that we are acquainted with matter, and
with all its elements, and yet we cannot even guess at the cause
of electricity, or explain the laws of the formation of the stones
which fall from meteors. There may be beings,--thinking beings,
near us, surrounding us, which we do not perceive, which we can
never imagine. We know very little; but, in my opinion, we know
enough to hope for the immortality, the _individual immortality of
the better part of man_.

"I have been led into all this speculation, which you may well
think wild, in reflecting upon the fate of Gregory! my feeling has
given erring wings to my mind. He was a noble fellow, and would
have been a great man.--Oh! there was no reason for his dying--he
ought not to have died.

"Blessings wait on you, my good fellow! Pray remember me to Tobin,
and, if you read this letter to him, protest, the moment he begins
to argue against the immortality of man!

"I came yesterday from the borders of Dorsetshire, where I have
been since Monday, seduced to travel by a friend. I was within
sixty miles of you, and saw divers fair trout-streams: let the fish
beware of me,--I shall be at them on Monday."

I have included this latter sentence in my extract, as being highly
characteristic of the writer. His passion for angling betrayed
itself upon all occasions; and the sport was alike his relief in
toil, and his solace in sorrow. To his conversation, as well as to
his letters, we may aptly apply the words of the Augustan poet:--

    "Desinit in piscem----formosa superne."

Whenever I had the honour of dining at his table, the conversation,
however it might have commenced, invariably ended on fishing; and
when a brother of the angle happened to be present, you had the
pleasure of hearing all his encounters with the finny tribe--how
he had lured them by his treachery, and vanquished them by his
perseverance. He would occasionally strike into a most eloquent and
impassioned strain upon some subject which warmed his fancy; such,
for example, as the beauties of mountain scenery; but before you
could fully enjoy the prospect which his imagination had pictured,
down he carried you into some sparkling stream, or rapid current,
to flounder for the next half hour with a hooked salmon!

I remember witnessing, upon one of these occasions, a very amusing
scene, which may be related as illustrative of some peculiarities
of his temper. I believe all those who have accompanied Davy in
his fishing excursions, will allow that no sportsman was ever
more ambitious to appear skilful and lucky. Nothing irritated him
so much as to find that his companions had caught more fish than
himself; and if, during conversation, a brother fisherman surpassed
him in the relation of his success, he betrayed similar impatience.

There happened to be present, on the occasion to which I allude, a
skilful angler, and an enterprising chemist. The latter commenced
on some subject connected with his favourite science; but Davy,
who, generally speaking, disliked to make it a subject of
conversation, suddenly turned to the angler, and related what he
considered a very surprising instance of his success: his sporting
friend, however, mortified him by the relation of a still more
marvellous anecdote; upon which Davy as quickly returned to the
chemist, who, in turn, again sent him back to the angler:--and thus
did he appear to endure the unhappy fate of the _flying fish_, who
no sooner escapes from an enemy in the regions of air, than he is
pursued by one equally rapacious in the waters.--But to return to
the thread of our history.

In referring to the records of the Institution, it appears that
in January 1805, Davy greatly enriched the cabinets of the
Institution by a present of minerals. The following are the Minutes
of the Committee upon this occasion:

"January 21, 1805.--Mr. Hatchett reported that, in pursuance of the
request of the Managers, he had inspected the minerals presented
to the Royal Institution by Mr. Davy, and that the aggregate value
(including the duplicate specimens) appears to him to exceed one
hundred guineas."

"January 28.--The Managers took into consideration Mr. Hatchett's
report at the last meeting, and resolved that Mr. Davy is entitled
to the thanks of the Managers for having added so valuable a
present to the collection of minerals belonging to the Institution."

On the 4th of February, it was Resolved--"That Mr. Davy be
appointed Director of the Laboratory, at a salary of one hundred
pounds a-year; by which his annual income from the Institution was
raised to four hundred pounds. At this period he delivered a series
of lectures on Geology, or on the chemical history of the earth; to
which we find an allusion in the following letter."


    TO THOMAS POOLE, ESQ.

    February, 1805.

    MY DEAR POOLE,

    I AM very much obliged to you for your last kind letter, and I
    thank you most sincerely for the exertion of your friendship at
    Bath. I thank you with very warm feelings.

    I hope you will soon come to town; that you will stay a long time;
    and that we shall be very much together.

    I paid your subscription to Arthur Young for the Smithfield Club.
    Pray, at all times, command me to do any thing I can for you in
    London:--you cannot teaze me; and though I am a very idle fellow,
    yet I can always work if the stimulus be the desire of serving such
    a friend as yourself.

    I am giving my course of lectures on Geology to very crowded
    audiences. I take a great interest in the subject; and I hope the
    information given will be useful.

    There has been no news lately from Coleridge; the last accounts
    state that he was well in the autumn, and in Sicily. On that poetic
    ground, we may hope and trust that his genius will call forth some
    new creations, and that he may bring back to us some garlands of
    never-dying verse. I have written to urge him strongly to give a
    course of lectures on Poetry at the Royal Institution, where his
    feeling would strongly impress, and his eloquence greatly delight.
    I am, my dear Poole, most affectionately Yours,

    H. DAVY.


On the 20th of May, in this year, Mr. Hatchett reported to the
Managers of the Institution--"that Mr. Davy proposed making a
journey into Wales and Ireland this summer, having in view to
collect specimens for enriching the mineralogical cabinets;" in
consequence of which it was Resolved--"That the sum of one hundred
pounds be entrusted to Mr. Davy to purchase minerals, and to defray
the incidental charges; and that the boy of the Laboratory,
William Reeve,[51] be ordered to attend him on his tour, and that
the steward be directed to defray his expenses."

  [51] There are some circumstances of interest connected with the
  history of this young man. He possessed much chemical talent; but
  during his residence in Ireland he was converted to the Catholic
  religion, and is at this time a Catholic priest in some part of
  the Continent.

From the following letters, it would appear that, having
accomplished his purpose of visiting Ireland, he made a rapid
journey into Cornwall for the sake of seeing his mother and sisters.


    TO DAVIES GIDDY, ESQ.

    Okehampton, September 1805.

    MY DEAR SIR,

    I am accompanying my friend Mr. Bernard in a tour through the West
    of England, and I hope we shall reach Penzance in two or three days.

    Mr. Bernard wishes much for the honour of your acquaintance, and I
    trust you will permit me to have the pleasure of making you known
    to him. Much kindness and long knowledge of him, may have made me
    partial to that gentleman, and may perhaps influence me when I say,
    that there is not a more patriotic, good, and public-spirited man
    in Great Britain.

    I came from Ireland by the western road, about a fortnight ago.
    My expectations were fully satisfied with the appearances of the
    "Giant's Causeway." The arrangements of rocks of the Northern Cape
    of Ireland appear to me to present facts equally irreconcilable
    upon either the Plutonic or Neptunian theory; and I am convinced
    that general fanciful theories will lose ground in proportion as
    minute observations are multiplied.

    The Irish are a noble race, degraded by slavery, and bearing
    the insignia of persecution, extreme savageness, or the lowest
    servility; yet they are ingenious and active, and seem to me to
    possess all the elements of power and usefulness; but amongst the
    lower orders there is a most unfortunate equality, destructive of
    all great and efficient exertion; and amongst the higher classes
    the greatest degree of activity is awakened only by the desire of
    imitating the English, and that not so much in their virtues and
    talents, as in their luxuries and follies.

    I hear from all quarters of the good effects of your late exertions
    in Parliament. May your efforts tend to establish the reign of good
    sense and pure philosophy, in a place where they have been too
    often found to yield to empty sounds!

    Yours, &c. H. DAVY.


    TO THOMAS POOLE, ESQ.

    London, Oct. 9, 1805.

    MY DEAR POOLE,

    I MADE a very rapid journey to Cornwall with Mr. Bernard, merely
    for the sake of showing him the country, and for the purpose of
    spending a week with my mother and sisters.

    We made an effort to come to you at Nether Stowey, but the people
    at Bridgewater would not take us round, through Stowey, to Taunton,
    without four horses; and at all events we could only have spent
    two or three hours with you; and it is difficult to say whether
    the pleasure of meeting, or the regret at parting so soon, would
    have been the greatest. I long very much for the intercourse of
    a week with you. I have very much to say about Ireland. It is
    an island which might be made a new and a great country. It now
    boasts a fertile soil, an ingenious and robust peasantry, and
    a rich aristocracy; but the bane of the nation is the equality
    of poverty amongst the lower orders. All are slaves without the
    probability of becoming free; they are in the state of equality
    which the _Sansculottes_ wished for in France; and until emulation
    and riches, and the love of clothes and neat houses, are introduced
    amongst them, there will be no permanent improvement.

    Changes in political institutions can at first do little towards
    serving them. It must be by altering their habits, by diffusing
    manufactories, by destroying _middle-men_, by dividing farms,[52]
    and by promoting industry by making the pay proportioned to the
    work. But I ought not to attempt to say any thing on the subject
    when my limits are so narrow; I hope soon to converse with you
    about it.

    I found much to interest me in geology in Ireland, and I have
    brought away a great deal of information, and many specimens.

    I shall now be in London till Christmas, with the exception of next
    week, which I am obliged to pass in Bedfordshire. I am, my dear
    Poole,

    Most affectionately your's,

    H. DAVY.

  [52] He means that the _middle-men_ being discontinued, their
  large allotments should be divided into farms of convenient
  extent, the occupiers of which should rent immediately from the
  owners of the soil.


After the Giant's Causeway, the scenery which called forth Davy's
greatest admiration in Ireland was that of Fair-Head. To an
enthusiastic lover of the wild and sublime features of Nature, an
object of greater interest could scarcely be presented than a vast
promontory, the summit of which rises five hundred feet above the
sea, and at whose base lies a waste of rude and gigantic columns,
swept by the hand of Time from the mountain to which they formerly
belonged.

The following fragment, written by Davy at the time, has been
placed in my hands by Mr. Greenough.


        "----But chiefly thee, Fair-Head!
    Unrivall'd in thy form and majesty!
    For on thy loftiest summit I have walk'd
    In the bright sunshine, while beneath thee roll'd
    The clouds in purest splendour, hiding now
    The Ocean and his islands--parting now
    As if reluctantly: whilst full in view
    The blue tide wildly roll'd, skirted with foam,
    And bounded by the green and smiling land,
    The dim pale mountains, and the purple sky.
    Majestic cliff! thou birth of unknown Time,
    Long had the billows beat thee, long the waves
    Rush'd o'er thy hollow'd rocks, ere life adorn'd
    Thy broken surface, ere the yellow moss
    Had tinted thee, or the mild dews of Heaven
    Clothed thee with verdure, or the eagles made
    Thy cave their aëry: so in after time
    Long shalt thou rest unalter'd mid the wreck
    Of all the mightiness of human works;
    For not the lightning nor the whirlwind's force,
    Nor all the waves of ocean, shall prevail
    Against thy giant strength--and thou shalt stand
    Till the Almighty voice which bade thee rise
    Shall bid thee fall."


Amongst Davy's letters to Mr. Gilbert, in the years 1804 and 1805,
I find several upon the subject of the elastic force of steam,
at different temperatures, with reference to Mr. Trevitheck's
improvements in the steam-engine; in one of which he says, "I shall
be extremely happy to hear of the results of your enquiries, and
I hope you will not confine them to your friends, but make them
public. Whenever speculative leads to practical discovery, it ought
to be well remembered, and generally known: one of the most common
arguments against the philosophical exercise of the understanding
is, _Cui bono?_ It is an absurd argument, and every fact against
it ought to be carefully registered. Trevitheck's engine will not
be forgotten; but it ought to be known and remembered that your
reasonings and mathematical enquiries led to the discovery."

On the 28th of February 1805, was read before the Royal Society,
and published in the Transactions of that year, a paper entitled,
"An Account of some analytical Experiments on a mineral production
from Devonshire, consisting principally of Alumina and Water; by
Humphry Davy, &c."

This mineral was first discovered by Dr. Wavel, in small veins
and cavities, in a tender argillaceous slate, near Barnstaple in
Devonshire. At first it was considered as a species of _Zeolite_,
until Mr. Hatchett concluded, from its geological position, that
it did not belong to that family of minerals. Dr. Babington
subsequently suspected from its physical characters, and from some
of its habitudes with acids, that it was a mineral not before
described, and accordingly placed a quantity of it in Davy's hands
for analysis; who, on finding in its composition little more than
clay and water, proposed to change the name of _Wavellite_ for that
of _Hydrargyllite_, as better expressive of its chemical nature. He
however, at the same time, alludes to traces of an acid which he
was unable to identify.

In a letter to Mr. Nicholson, dated Killarney, June 15, 1806, and
which was afterwards published in his Journal, Davy refers to this
fact in the following manner:--


    DEAR SIR,

    I SHALL feel much obliged to you to mention that I have found the
    acid which exists in minute quantities in Wavellite to be the
    _Fluoric acid_, in such a peculiar state of combination as not to
    be rendered sensible by sulphuric acid. I am, &c.

    H. DAVY.


My late friend the Reverend William Gregor, having found the
Wavellite at Stenna Gwynn, in Cornwall, submitted it to experiment,
and the result certainly established the conclusion of the presence
of fluoric acid, though not rendered apparent by the usual tests.
The facts were transmitted to the Royal Society, and published in
a paper entitled, "On a mineral Substance, formerly supposed to be
Zeolite; by the Reverend William Gregor."

The subsequent experiments of Berzelius, however, cleared away the
obscurity in which the subject was still involved. He showed that
this mineral not only contained in its composition a small portion
of the _neutral fluate of alumina_, but he demonstrated the
presence of a _sub-phosphate_ of that earth, to no inconsiderable
an amount. Much has been said of the error committed on this
occasion by Davy, in overlooking thirty-three per cent. of
phosphoric acid; but the _phosphate of alumina_ is a body that
might very easily have escaped notice at a period when mineral
analysis was in a far less advanced state than it is at present.

On the 16th of May 1805, Davy communicated to the Royal Society a
paper "On the method of analyzing Stones containing a fixed Alkali,
by means of the Boracic Acid." This method was founded upon two
important facts: first, on the considerable attraction of boracic
acid for the different simple earths at the heat of ignition;
and, secondly, on the facility with which the compounds so formed
are decomposed by the mineral acids. The processes are extremely
simple, and the method must be considered as having advanced the
art of mineral analysis.

For this and his preceding papers, the President and Council of the
Royal Society adjudged to him their Copley medal.

In 1806, Mr. Poole, having consulted Davy on the subject of a
Mine occurring near Nether Stowy, received from him the following
letter, which is interesting from the political opinions it
displays.


    TO THOMAS POOLE, ESQ.

    MY DEAR POOLE,

    What you have written concerning the indifference of men with
    regard to the interest of the species in future ages, is perfectly
    just and philosophical; but the greatest misfortune is, that men
    do not attend even to their own interest, and to the interest of
    their own age in public matters. They think in moments, instead
    of thinking, as they ought to do, in years; and they are guided
    by expediency rather than by reason. The true political maxim
    is, that the good of the whole community is the good of every
    individual; but how few statesmen have ever been guided by this
    principle! In almost all governments, the plan has been to
    sacrifice one part of the community to other parts:--sometimes,
    the people to the aristocracy; at other times, the aristocracy to
    the people;--sometimes, the Colonies to the Mother-country; and
    at other times, the Mother-country to the Colonies. A generous
    enlightened policy has never existed in Europe since the days
    of Alfred; and what has been called "the balance of power"--the
    support of civilization,--has been produced only by jealousy, envy,
    bitterness, contest, and eternal war, either carried on by pens or
    cannon, destroying men morally and physically! But if I proceed in
    vague political declamation, I shall have no room left for the main
    object of my letter--your Mine. I wish it had been in my power to
    write decidedly on the subject; but your county is a peculiar one:
    such indications would be highly favourable in Cornwall; but in
    a _shell-limestone_ of late formation, there have as yet been no
    instances of great copper mines. I hope, however, that your mine
    will produce a rich store of _facts_.

    Miners from Alston Moor, or from Derbyshire, would understand your
    country better than Cornish miners, for the Cornish shifts are
    wholly different from yours. It would be well for you to have some
    workmen at least from the North, as they are well acquainted with
    _shell-limestone_.

    The Ecton copper mine in Staffordshire is in this rock: it would be
    right for you to get a plan and a history of that mine, which might
    possibly assist your views.

    Had I been rich, I would adventure; but I am just going to embark
    with all the little money I have been able to save for a scientific
    expedition to Norway, Lapland, and Sweden. In all climes, I shall
    be your warm and sincere friend,

    H. DAVY.


On the death of Dr. Edward Whitaker Gray, Secretary of the Royal
Society, Davy was elected into that office, at an extraordinary
meeting of the Society, on the 22nd of January 1807; and at the
same time he was elected a member of the Council.

We are now advancing to that brilliant period in the history of
our philosopher, at which he effected those grand discoveries in
science, which will transmit his name to posterity, associated with
those of Newton, Bacon, Locke, and the great master-spirits of
every age and country:--I speak of his developement of the LAWS OF
VOLTAIC ELECTRICITY.

I approach the subject with that diffidence which the contemplation
of mighty achievements must ever produce in the mind of the
historian, when he compares the extent and magnitude of his subject
with the limited and feeble powers which are to describe them.

As the advantages afforded by the history of any great discovery
consist as much in exhibiting, step by step, the intellectual
operations by which it was accomplished, as in detailing its
nature and applications, or in examining its relations with
previously established truths; so shall I be unable to preserve
a chronological succession in the examination of those several
memoirs which he presented to the Royal Society, without breaking
asunder that fine intellectual thread, by which his mind was
conducted through the intricate paths of nature from known to
unknown phenomena. For this reason, although I announced, according
to the date of its publication, the subject of his first paper
on electricity, I deferred entering upon its examination, until
I might be able to bring into one uninterrupted view the whole
enquiry, in all its branches and bearings.

It is impossible to enter upon the subject of galvanism, or Voltaic
electricity, without recurring to the circumstance which first
betrayed the existence of such an energy in nature, and to the
sanguine expectations which the discovery so naturally excited.

On witnessing the powerful contraction of a muscular fibre by
the mere contact of certain metals, it was rational to conclude,
that the nature and operation of the mysterious power of vital
irritability might, at length, be discovered by a new train of
scientific research. It is a curious fact, that an experiment so
full of promise to the physiologist should have hitherto failed
in affording him any assistance in his investigations; while the
chemist, to whom it did not, at first, appear to offer any one
single point of interest, has derived from it a new and highly
important instrument of research, which has already, under the
guidance of Davy, multiplied discoveries with such rapidity, and
to such an extent, that it is not even possible to anticipate the
limits of its power.

We have here, then, another striking instance of a great effect
produced by means apparently insignificant. Who could have
imagined it possible, that the spasmodic action occasioned in the
limb of a frog, by the accidental contact of a pair of scissors,
should have become the means of changing the whole theory of
chemistry--of discovering substances, whose very existence was
never suspected--of explaining the anomalous associations of
mineral bodies in the veins of the earth--of protecting surfaces
of metal from the corrosive action of the elements--of elucidating
the theories of volcanoes and earthquakes--and, may we not add? of
leading the way to a knowledge of the laws of terrestrial magnetism!

Such an unexpected extension of an apparently useless fact should
dispose us to entertain a kinder regard for the labours of one
another, and teach us to judge with diffidence of the abstract
results of science. A discovery which may appear incapable of
useful application to-day, may be our glory to-morrow,--it may even
change the face of empires, and wield the destiny of nations.

The conic sections of Apollonius Pergæus remained useless for two
thousand years: who could have supposed that, after the lapse of
twenty centuries, they would have formed the basis of astronomy?--a
science giving to navigation safety, guiding the pilot through
unknown seas, and tracing for him in the heavens an unerring path
to his native shores.

Some apology may be necessary for this digression; but, I
confess, the subject has always appeared to me to be capable
of much interesting illustration, and I heartily concur in the
opinion expressed by the accomplished author of "Lettres à
Sophie"--"_L'Histoire des grands effets par les petites causes
ferait un livre bien curieux._"




CHAPTER VI.

   The History of Galvanism divided into six grand Epochs.--Davy
   extends the experiment of Nicholson and Carlisle.--His Pile
   of one metal and two fluids.--Dr. Wollaston advocates the
   doctrine of oxidation being the primary cause of Voltaic
   Phenomena.--Davy's modification of that theory.--His Bakerian
   Lecture of 1806.--He discovers the sources of the Acid and
   Alkaline matter eliminated from water by Voltaic action.--On
   the nature of Electrical decomposition and transfer.--On
   the relations between the Electrical energies of bodies,
   and their Chemical Affinities.--General developement of the
   Electro-chemical Laws.--Illustrations, Applications, and
   Conclusions.


The History of Galvanism may be divided into six grand epochs; each
being distinguished by the discovery of facts variously interesting
from their novelty, and from the extent and importance of their
applications.

It cannot be expected that I should enter into a minute history of
the science; such a labour would require a distinct work for its
accomplishment. I shall therefore follow the plan of the architect,
who, in presenting a finished drawing of a part, sketches a faint
outline of the whole edifice to which it belongs, in order that its
fair proportions may appear in proper breadth and relief.

The FIRST EPOCH may be considered as arising out of the fundamental
fact discovered by Galvani in 1790--that the contact of two
different metals with the nerve of a recently killed frog will
excite distinct muscular contractions.

THE SECOND EPOCH may be dated from the discovery of what might be
termed _Organic_ Galvanism, or the production of its influence,
without the presence of animal organs, by the peculiar action of
metals upon water, as first observed by Dr. Ash.

THE THIRD EPOCH will long be celebrated on account of the discovery
of the accumulation of the Galvanic power, by the invention of the
pile of Volta, made known in the first year of the present century,
and which so distinctly exhibited the analogy between Galvanism and
Electricity, that the energy thus excited is now generally spoken
of as "_Voltaic Electricity_."

THE FOURTH EPOCH may be considered as founded upon the knowledge of
the general connexion between the excitement of Voltaic electricity
and chemical changes.

THE FIFTH EPOCH is exclusively indebted for its origin to Davy--the
establishment of the general law, that Galvanism decomposes all
compound bodies, and that the decomposition takes place in a
certain determinate manner.

THE SIXTH AND LAST EPOCH is founded upon the discovery of the
relations subsisting between electricity and magnetism; giving
origin to a new branch of science, which has been distinguished by
the name of "ELECTRO-MAGNETISM."

Galvani,[53] from the moment of his first discovery, always
referred the effects he produced to an electrical origin; but he
considered that the metals employed merely acted as conductors,
which effected a communication between the different parts of an
animal, naturally, or by some process of nature, in opposite states
of electricity, and that the muscular contractions took place
during the restoration of the equilibrium.

  [53] The simple fact relating to the action of metals on the
  animal organs was certainly not first observed by Galvani, but by
  Sulzer, who has described the sensation of taste produced by the
  contact of lead and silver with the tongue, in his _Théorie des
  Plaisirs_, in 1767.

Until the researches of Dr. Ash,[54] Ritter, Fabroni, and Creve,
had been made known, the Galvanic influence was generally
considered as existing only in the living organs of animals, from
which it might be elicited by certain processes.

  [54] M. Humboldt (_Ueber die gereize Faser_, l. 473, 1797,)
  quotes part of a letter from Dr. Ash, in which it is said that,
  "if two finely polished plates of homogeneous zinc be moistened
  and laid together, little effect follows; but if zinc and silver
  be tried in the same way, the whole surface of the silver
  will be covered with oxidated zinc. Lead and quicksilver act
  as powerfully upon each other, and so do iron and copper." M.
  Humboldt says, that, in repeating this experiment, he saw air
  bubbles ascend, which he supposes to have been hydrogen gas from
  the decomposition of water.

In the Bakerian Lecture[55] read before the Royal Society in
1826, Davy, in giving a retrospective view of the progress of
Electro-chemical Science, very justly remarks, that the true
origin of all that has been done in this department of philosophy
was the accidental discovery of Nicholson and Carlisle, of the
decomposition of water by the pile of Volta, on the 30th of April,
in the year 1800; which was immediately followed by that of the
decomposition of certain metallic solutions, and by the observation
of the separation of alkali on the negative plates of the
apparatus. Mr. Cruickshank, in pursuing these experiments, obtained
many new and important results, such as the _decomposition of the
muriates of magnesia_, _soda_, and _ammonia_; and also observed the
fact, that alkaline matter always appeared at the negative, and
acid matter at the positive pole.[56]

  [55] As this lecture will be frequently mentioned in the progress
  of these Memoirs, in connexion with most important discoveries,
  it may be interesting to the reader to learn something of its
  foundation and design. I have therefore collected the necessary
  information from the Minutes of the Royal Society. Mr. Baker is
  well known in the history of Science, as an accurate observer
  with the microscope, and as the author of several works on the
  subject. By his will, dated July 1763, he bequeathed the sum
  of one hundred pounds, the interest of which he directed "to
  be applied for an Oration or Discourse, to be read or spoken
  yearly by some one of the Fellows of the Royal Society, on such
  parts of Natural History, or Experimental Philosophy, at such
  time, and in such manner, as the President and Council of the
  said Society shall please to order and appoint; on condition,
  nevertheless, that if any one year shall pass after the payment
  of the said hundred pounds, without such oration or discourse
  having been read or spoken at some Meeting of the said Royal
  Society, the said hundred pounds shall then become forfeited, and
  shall be repaid by the said Society to his executors," &c. Baker
  died in November 1774, and in the following year a Fellow was
  nominated to read the lecture. It is a whimsical circumstance,
  that the first lecturer should have been PETER WOULFE, the last
  of the alchemists. The names of the successive lecturers were as
  follow:--Dr. Ingenhouz, Mr. Cavallo, Mr. Vince, Dr. Wollaston,
  Dr. Young, Sir H. Davy, Mr. Brande, Captain Kater, Captain Edward
  Sabine, and Mr. Herschel.

  [56] Nicholson's Journal, vol. iv. p. 190.

No sooner had Davy become acquainted with the curious experiments
of Nicholson and Carlisle, than, as we learn from his letter to
Mr. Gilbert,[57] bearing the date of July 1800, he proceeded to
repeat them. Indeed, it was the early habit of his mind not only to
originate enquiries, but without delay to examine the novel results
of other philosophers; and in numerous instances it would seem,
that he only required to confirm their accuracy before he succeeded
in rendering the application of them subservient to farther
discovery. This was certainly the case with respect to the subject
before us: he was a discoverer as soon as he became an enquirer. It
is admirable to observe with what a quick perception he discovered
the various bearings of a new fact, and with what ingenuity
he appropriated it for the explanation of previously obscure
phenomena. In referring to the "Additional Observations" appended
to his "Chemical Researches," we shall find that the moment he
became acquainted with the experiments of Dr. Ash, he proceeded to
enquire how far the fact, previously noticed by himself, of the
conversion of nitrous _gas_ into nitrous _oxide_, by exposure to
wetted zinc, might depend upon galvanic action.

  [57] See page 85.

In the month of September 1800, he published his first paper on the
subject of Galvanic Electricity, in Nicholson's Journal, which was
followed by six others, in which he so far extended the original
experiment of Nicholson and Carlisle, as to show that oxygen and
hydrogen might be evolved from separate portions of water, though
vegetable and even animal substances intervened; and conceiving
that all decompositions might be _polar_, he electrized different
compounds at the different extremities, and found that sulphur
and metallic bodies appeared at the _negative_ pole, and oxygen
and azote at the _positive_ pole, though the bodies furnishing
them were separated from each other. Here was the dawn of the
Electro-chemical theory.

In a letter to Mr. Gilbert, already printed in these Memoirs,[58]
he announced his opinion that Galvanism is a process principally
chemical; and in a subsequent communication[59] to the same
gentleman, written on the eve of his departure from Bristol to the
Royal Institution, we discover a farther developement of the same
theory, which, although modified by future researches, became, as
we shall hereafter find, materially instrumental in establishing
juster views of the nature of Voltaic action.

  [58] See page 110.

  [59] Page 118.

As soon as it was discovered that galvanic power might be excited
by the contact of metals, without the interposition of animal
organs, it was imagined that the electricity was set in motion
by the contact of bodies possessing different conducting powers,
without any reference to the chemical action which accompanied the
process. This theory was naturally suggested by the fact discovered
by Mr. Bennett several years before--that _electricity is excited
by the mere contact of different metals_: thus, when a plate of
copper and another of zinc, each furnished with an insulating
glass handle, are made to touch by their flat surfaces, the zinc,
after separation, exhibits _positive_, and the copper _negative_
electricity. In this case, it is fair to conclude that a certain
quantity of electricity had moved from the copper to the zinc.

On trying other metals, Volta found that similar phenomena arose;
from which property such bodies have been denominated "_motors_" of
electricity, and the process which takes place _electro-motion_:
terms which have since been sanctioned and adopted by Davy.

It is on this transference of electricity from one surface to
another, by simple contact, that Volta explains the action of
the pile invented by himself, as well as that of all similar
arrangements. The interposed fluids, on this hypothesis, have no
effect as chemical agents, in producing the phenomena; they merely
act as conductors of the electricity.

We have seen how early Davy had observed the intimate connexion
subsisting between the electrical effect, and the chemical changes
going on in the pile, and that he accordingly drew the conclusion
of the dependence of the one upon the other. In fact, the most
powerful Voltaic combinations are those formed by substances that
act chemically upon each other with the greatest energy; while
such as undergo no chemical change exhibit no electrical powers:
thus zinc, copper, and nitric acid form a powerful battery; whilst
silver, gold, and water, which do not act upon each other, produce
no sensible effect in a series of the same number.

Although, in this obscure region of research, we are as yet unable
to discover the nature of the power by which electricity is
accumulated, it was a considerable step towards a true theory to
have ascertained the insufficiency of the proposition that had
been offered in explanation of the phenomena.

An investigation into the chemical activity of the pile led Davy
to the discovery of a new series of facts, to which we find
an allusion in his former letters to Mr. Gilbert, and which
subsequently formed the basis of his first communication read
before the Royal Society on the 18th of June in the same year.

All the combinations analogous to the Voltaic pile had hitherto
consisted of a series containing, at least, _two_ metallic
bodies, (or one metal and charcoal,) and a stratum of fluid. Davy
discovered that an accumulation of galvanic energy, exactly similar
to that in the common pile, might be produced by the arrangement
of _single_ metallic plates with _different_ strata of fluids; so
that, instead of composing a battery with _two_ metals and _one_
fluid, he succeeded in constructing it with _one_ metal and _two_
fluids; provided always that oxidation, or some equivalent chemical
change, should proceed on one of the metallic surfaces only.

In describing these combinations of a single metal with two fluids,
he divides them into three classes, following in the arrangement
the order of time with regard to their discovery.

In the First Class, one side of the metallic plate is oxidated;
in the Second, a sulphuret is formed on one of its surfaces; and
in the Third, both sides are acted upon, the metal becoming a
_sulphuret_ on one of its surfaces, and an _oxide_ on the other.

The apparatus which he employed for these experiments is preserved
in the laboratory of the Royal Institution. It consists of a
trough, containing grooves capable of receiving the edges of the
different plates necessary for the arrangement, one half of which
are composed of horn, the other half of some one metal.

When the apparatus was used, the cells were filled, in the galvanic
order, with the different solutions, according to the class of the
combination, and connected in pairs with each other by slips of
moistened cloth carried over the non-conducting plates.

At the meeting of the Royal Society, following that on which the
above interesting facts were communicated, Dr. Wollaston presented
a memoir of considerable importance, entitled, "Experiments on
the Chemical Production and agency of Electricity;" in which he
strongly advocates the truth of that theory which recognises
metallic oxidation as the _primary_ cause of the Voltaic phenomena.
This paper is also farther important as it proves, by most
ingeniously devised experiments, not only the similarity of the
means by which both common and galvanic electricity are excited,
but also the resemblance existing between their effects; showing,
in fact, that they are both essentially the same, and confirming
the opinion, that all the apparent differences may depend upon
differences in intensity and quantity.

Acting upon this principle, Dr. Wollaston succeeded in producing a
very close imitation of the chemical action of galvanism by common
electricity; such, for example, as the decomposition of water, and
other effects of oxidation and deoxidation.[60] In the prosecution
of this train of research, he displays, in a very striking
manner, that attention to minute arrangement which so remarkably
characterised all his manipulations. I particularly allude to
the expedients by which he reduced the extremity of a gold wire,
in order to apportion the strength of the electric charge to the
quantity of water submitted to its influence.

  [60] M. Bonijol of Geneva has lately succeeded in effecting
  the decomposition of _Potash_ and the _Chloride of Silver_ by
  ordinary electricity. His process consists in placing these
  substances in a very narrow glass tube, and in then passing a
  series of electric sparks from the ordinary machine through
  them. The electricity was conducted into the tube by means of
  two metallic wires fixed into the ends. When a quick succession
  of electric sparks had taken place for about five or ten
  minutes, the tube containing chloride of silver was found to
  contain reduced silver; and when potash had been submitted to
  the electric current, then the Potassium was seen to take fire
  as it was produced. The same philosopher has likewise contrived
  to decompose water by atmospheric electricity. The electricity,
  in this case, is collected from the atmosphere by means of a
  very fine point fixed at the extremity of an insulated rod; the
  latter is connected with the apparatus, in which the water is to
  be decomposed, by a metallic wire, of which the diameter does
  not exceed 1-50th of an inch. In this way the decomposition of
  the water proceeds in a continuous and rapid manner, although
  the atmospheric electricity be not strong. Stormy weather, it is
  said, is quite sufficient for the purpose.--_Bib. Univers._ 1830,
  p. 213. and _Royal Institution Journal_, No. 2.

Although it is now very generally admitted, that the chemical
agency of the fluids upon the metals employed is highly essential
to the maintenance of Voltaic action, there still remains
considerable doubt as to how far we are entitled to regard it as
the first in the order of phenomena.

At a later period of his researches, Davy suggested as a correction,
or rather modification, of the theory of Volta, that the
electro-motion produced by the contact of the metals might
be the primary cause of the chemical changes; and that such
changes were in no other way efficient, than in restoring the
electric equilibrium thus disturbed: it was farther held, that
this equilibrium could not be permanent, that it could in fact be
only momentary; since, in consequence of the imperfect conducting
power of the interposed fluid, the zinc and copper-plates, by their
electro-motive power, would again assume their opposite states
of electricity; and that these alternate changes would occur,
as long as any of the fluid remained undecomposed. In a Voltaic
arrangement, then, there would appear to exist, if the expression
may be allowed, a kind of electrical seesaw; the apposition of
the metals destroying the equilibrium, and the resulting chemical
changes again restoring it. It has, however, been very justly
observed, that the application of electricity, as an instrument
of chemical decomposition, has most fortunately no connexion with
such theories, and that the study of its effects may be carried on
without reference to any hypothetical notions concerning the origin
of the phenomena.

An interval of nearly five years had elapsed between the first
communication which Davy made on this subject, and the Bakerian
lecture which is immediately to be considered. During this period
several new facts had been added by different experimentalists, but
they were scattered, disjointed, and totally unconnected with each
other by any rational analogies.

The constant appearance of acid and alkaline matter in pure water,
when submitted to the influence of the Voltaic pile, gave rise
to the most extravagant speculations and discordant hypotheses.
Various statements were made, both in Italy and England, respecting
the _generation_ of muriatic acid, and that of the fixed alkalies,
under these circumstances. Mr. Sylvester affirmed, that if two
separate portions of water were electrised out of the contact of
substances containing alkaline or acid matter, acid and alkali
would, nevertheless, be produced.

Some philosophers sought to explain the phenomenon from the salts
contained in the fluids of the trough, which they imagined might,
by some unsuspected channel, find their way into the water under
examination. Others believed that they were actually _generated_
by the union of the electric fluid with the water, or with one or
both of its elements; so that, up to the time of Davy's masterly
researches, the subject was involved in the greatest obscurity; and
whether the saline matter was liberated from unknown combinations,
or at once formed by the union of its elements, was a question upon
which the greatest chemists entertained different opinions.

The Bakerian Lecture, read before the Royal Society on the 20th of
November 1806, not only set this question for ever at rest, but
unfolded the mysteries of general Voltaic action; and, as far as
theory goes, may almost be said to have perfected our knowledge of
the chemical agencies of the pile.

This grand display of scientific light burst upon Europe like a
splendid meteor, throwing its radiance into the deepest recesses,
and opening to the view of the philosopher new and unexpected
regions.

I shall endeavour to offer as popular a review of this celebrated
memoir, as the abstruse and complicated nature of its subjects will
allow; and I shall be careful in pointing out the successive stages
of the enquiry; for we are all too much in the habit of exclusively
looking after results; whereas an examination of the steps by which
they were attained is far more important, not only to the fame of
the discoverer, but to ourselves, as the means of instruction.

The subjects investigated in this memoir are arranged under the
following divisions.

1. "On the changes produced in Water by Electricity.

2. "On the agencies of Electricity in the decomposition of various
compound Bodies.

3. "On the transfer of certain constituent Parts of Bodies by the
action of Electricity.

4. "On the passage of Acids, Alkalies, and other Substances,
through various attracting chemical menstrua, by means of
Electricity.

5. "Some general Observations on these Phenomena, and on the mode
of Decomposition and Transition.

6. "On the General Principles of the chemical changes produced by
Electricity.

7. "On the Relations between the Electrical Energies of bodies and
their Chemical Affinities.

8. "On the mode of action of the Pile of Volta, with Experimental
Elucidations.

9. "On some General Illustrations and Applications of the foregoing
facts and principles."

With respect to the first of these divisions, comprehending a
history of the changes produced in water by electricity, it is
worthy of particular notice, that as early as the year 1800,
while residing at Bristol, Davy had discovered that when separate
portions of distilled water, filling two glass tubes connected by
moist bladders, or any moist animal or vegetable substance, were
submitted to the electrical action of the Voltaic pile, by means
of gold wires, a _nitro-muriatic_ solution of gold appeared in the
tube containing the positive wire, and a solution of soda in the
opposite tube; but he soon ascertained that the muriatic acid owed
its appearance to the animal or vegetable matters employed; for
when the same fibres of cotton were used in successive experiments,
and washed after every process in a weak solution of nitric acid,
the water in the apparatus containing them, though acted upon for a
great length of time with a very strong power, produced no effect
upon a solution of nitrate of silver.

In every case in which he had procured much soda, the glass[61] at
the point of contact with the wire seemed considerably eroded; when
by substituting an agate for a glass cup, no fixed saline matter
could be obtained. Its source therefore, in the former case, was
evidently the glass.

  [61] It is perhaps a fact not very generally known, that glass,
  to a certain extent, is decomposable by water: if some of it in
  a powdered state be triturated with distilled water, in a short
  time the turmeric test will indicate a portion of alkali in
  solution.

With respect to Mr. Sylvester's experiment, already noticed, it
was sufficient to say that he conducted his process in a vessel of
_pipe-clay_, which not only contains lime, but may also include in
its composition some of the combinations of a fixed alkali.

On resuming the enquiry, it was Davy's first care to remove
every possible source of impurity: he accordingly procured cups
of agate, which, previously to being filled, were boiled for
several hours in distilled water; and a piece of very white and
transparent _amianthus_, a substance first proposed for this
purpose by Dr. Wollaston, having been similarly purified, was made
to connect the vessels together. Thus was every apparent source of
fallacy removed; but still, after having been exposed to Voltaic
action for forty-eight hours, the water in the positive cup gave
indications of muriatic acid, and that in the negative cup, of
soda! The result was as embarrassing as it was unexpected; but it
was far from convincing him that the bodies thus obtained were
_generated_:--but whence arose the saline matter? Did the agate,
after every precaution, still contain some very minute portion
of saline matter, not easily discoverable by chemical tests? To
determine this question, the experiment was repeated a second,
a third, and a fourth time: the quantities of saline matter
diminished in every successive operation, which sufficiently proved
that the agate must at least have been _one_ of the sources sought
for; but four additional repetitions of the process convinced
the operator that it could not be the only one; that there must
exist some other source from which the alkali proceeded, since
it continued to appear to the last, in quantities sufficiently
distinct, and apparently equal, in every experiment. This was
extremely perplexing: every precaution had been taken--the agate
cups had even been included in glass vessels, out of the reach of
the circulating air--all the acting materials had been repeatedly
washed with distilled water; and no part of them in contact with
the fluid had ever touched the fingers.

The water itself then, however pure it might appear, must have
furnished the alkali. The experiments were repeated in cones of
the purest gold, and the water contained in them was submitted to
Voltaic action for fourteen hours; the result was, that the acid
increased in quantity as the experiment proceeded, and at length
became even sour to the taste. On the contrary, the alkaline
properties of the fluid in the opposite cone shortly obtained a
certain intensity, and remained stationary.

On the application of heat, the alkaline indications became less
vivid, although there always remained, after the operation,
sufficient evidence to prove that a portion at least was fixed,
although probably mixed with ammonia.

The acid, as far as its properties could be examined, agreed with
those of pure nitrous acid, having an excess of nitrous gas.

It was now impossible to doubt that the water held in solution some
substance which was capable of yielding alkaline matter, but which,
from the minuteness of its quantity, had soon been exhausted.

The next step, therefore, was to submit the water to a still more
rigorous examination, which he did by evaporating it in a vessel of
silver; when he had the satisfaction to discover the 1-70th of a
grain of saline matter.

The water, thus purified in a vessel of silver, was again subjected
to Voltaic action in the cones of gold. After two hours, there was
only the slightest possible indication of alkali; and this was not,
as before, _fixed_, but entirely _volatile_.

In every one of these experiments, acid matter had been produced,
and it always presented the character of nitrous acid. Two of the
great sources of foreign matter had been detected and removed, viz.
the vessels, and the water employed; it still however remained to
be explained, how nitrous acid and ammonia could be produced in
cases where pure water and pure vessels had been used. In no part
of this elaborate enquiry is the penetration of Davy more striking,
than in his reasonings upon this problem, and in the beautiful
experiments which his sagacity suggested for its solution.

It occurred to him, that the nascent oxygen and hydrogen of the
water might respectively combine with a portion of the nitrogen
of the common air, which is constantly dissolved in that fluid;
but if this were the case, how did it happen that the production
of nitrous acid was progressive, while that of the alkali was
limited? The experiments of Dr. Priestley, on the absorption of
gases by water, at once suggested themselves to his mind as being
capable of solving this last difficulty; for that distinguished
philosopher had shown, that hydrogen, during its solution in
water, expelled the nitrogen, whereas oxygen and nitrogen were
capable of coexisting in a state of solution in that fluid. It was,
however, necessary to confirm the truth of this explanation by
experiment, and he accordingly introduced the two cones of gold,
containing purified water, under the receiver of an air-pump; the
exhaustion was effected, and the Voltaic pile brought to act upon
the water thus circumstanced; after eighteen hours the result was
examined, when the water in the negative cone produced no effect
upon prepared litmus, but that in the positive vessel did give it a
tinge of red barely perceptible.

Had his series of experiments terminated here, the truth of his
conclusions would have been established by the comparatively
small proportion of acid formed in this latter experiment; but he
determined to repeat it under circumstances, if possible, still
more unexceptionable and conclusive. Having, therefore, arranged
the apparatus as before, he exhausted the receiver, and then filled
it with hydrogen gas from a convenient air-holder; he made even a
second exhaustion, to ensure the highest accuracy, and then again
introduced carefully prepared hydrogen. The Voltaic process was
continued during twenty-four hours, and at the end of that period
it was found that neither the water in the positive nor in the
negative vessels altered the tint of litmus in the slightest degree.

Thus did he succeed in exposing the three great sources of fallacy
which had so long misled chemists, with regard to the generation
of acid and alkaline matter in Voltaic experiments, viz.--The
impurities of the vessels--the foreign matter contained in the
water--and the compounds generated by the combination of the
nitrogen of atmospheric air with the elements evolved from water;
and thus did he establish, by an unbroken chain of incontrovertible
evidence, the important truth, that "water, chemically pure, is
decomposed by electricity into gaseous matter alone--into oxygen
and hydrogen."

Out of the foregoing train of research very naturally sprang the
consideration of the _decomposing agencies of Electricity_. It had
been constantly observed, that, in all electrical changes connected
with the presence of acid and alkaline matter, the former uniformly
collected around the positive, and the latter around the negative
surface of the apparatus.

In one of the earliest experiments, Davy had also noticed that
glass underwent decomposition, and that its alkali always passed to
the negative surface. He was, therefore, led to enquire whether,
through electrical agency, different solid earthy compounds,
insoluble, or soluble with difficulty in water, might not be made
to undergo a similar decomposition. We shall find that the results
of the trials were decisive and satisfactory. For conducting
experiments of this description, he hit upon the happy expedient
of constructing the cups with the materials which he wished to
submit to experiment, and then by introducing water into them, and
forming the necessary connexion by means of asbestus, he completed
the Voltaic circuit. In this manner he submitted to experiment
_sulphate of lime_, _sulphate of strontia_, _fluate of lime_,
_sulphate of baryta_, &c. and with analogous results; the acid
element in each case passing to the positive, and the earthy base
to the negative cup.

As, in the above experiments, the bodies under examination were
presented in considerable masses, and exposed large surfaces to
the electric action, it became necessary to enquire whether minute
portions of acid and alkaline matter could, by the same agency, be
disengaged from solid combinations. This point was very readily
elucidated. A piece of fine grained basalt, which, by a previous
analysis, had been found to contain 3·5 per cent. of soda, nearly
·5 of muriatic acid, and fifteen parts of lime, having been
divided into two properly-shaped pieces, and a cavity, capable
of containing twelve grains of water, been drilled in each, was
submitted, as in former experiments, to the action of the pile. At
the end of ten hours, the result was examined with care, when it
appeared that the positively electrified water had the strong smell
of oxymuriatic acid, and copiously precipitated nitrate of silver;
while that which was negative affected turmeric, and left by
evaporation a residuum which appeared to consist of lime and soda.

A part of a specimen of compact zeolite from the Giants' Causeway,
and vitreous lava from Ætna, were each treated in a similar manner,
and with results equally satisfactory.

Having thus settled the question with regard to the disengagement
of the saline parts of bodies insoluble in water, he proceeded
to extend and multiply his experiments on soluble compounds,
the decomposition of which, as might have been supposed, always
proceeded with greater rapidity, and furnished results more
perfectly distinct. In these processes he employed the agate cups,
with platina wires, connected by amianthus moistened with pure
water; the solutions were introduced into these cups, and the
electrifying power applied in the manner already described. In this
way, _sulphate of potash_, _sulphate of soda_, _nitrate of potash_,
_phosphate of soda_, &c. were respectively examined; and in every
case the acid, after a certain interval, collected in the cup
containing the positive wire, and the alkalies and earths in that
containing the negative wire.

When metallic solutions were employed, metallic crystals or
depositions were formed on the negative wire, and oxide was
likewise deposited around it, while a great excess of acid was
found in the opposite cup.

With respect to the transfer of the constituent Parts of Bodies by
Electric Action, several original experiments were instituted, and
some important conclusions established.

Several facts had been stated, which rendered it probable that
the saline elements evolved in decompositions by electricity,
were capable of being transferred from one electrified surface to
another, according to their usual order of arrangement; but to
demonstrate this clearly, farther researches were required, and
Davy proceeded to supply the necessary evidence. He connected one
of the cups of sulphate of lime before mentioned, with a cup of
agate, by means of asbestus, and filling them with purified water,
connected them with the battery. In about four hours, a strong
solution of lime was found in the agate cup, and sulphuric acid in
the cup of sulphate of lime. By reversing the order of arrangement,
and carrying on the process during a similar period, the sulphuric
acid appeared in the agate cup, and the lime in the opposite
vessel. In both these experiments (the acid in the one case, and
the lime in the other), the elements of the substance must have
passed, in an imperceptible form, along the connecting line of
asbestus into the opposite vessel.

Many trials were made with other saline bodies, and with results
equally satisfactory; the base always passing into the vessel
rendered negative, and the acid into that which was positive.

The time required for these transmissions appeared to be, _cæteris
paribus_, in some proportion to the length of the intermediate
volume of water.

In the farther prosecution of the enquiry, Davy discovered a still
more extraordinary series of facts. In the first place, he found
that the contact of the saline solution with a metallic surface was
not in the least necessary for its decomposition. He introduced
purified water into two glass tubes, and connected with them, by
means of amianthus, a vessel containing a solution of muriate of
potash. In this case, the saline matter was distant from each of
the wires at least two-thirds of an inch; and yet alkaline matter
soon appeared in one tube, and acid matter in the other; and in
sixteen hours moderately strong solutions of potash and muriatic
acid had been formed.

The discovery of this fact became the key to that of others. He
very naturally proceeded to enquire into the progress of the
transfer, and into the course of the acid and alkaline elements;
when, by the use of litmus and turmeric, he arrived at the
following conclusion,--that acids and alkalies, during their
electrical transference, passed through water containing vegetable
colours without effecting in them any change. From which we are led
to the consideration of the fourth division of the subject, viz.
"On the Passage of Acids, Alkalies, and other Substances, through
various attracting Chemical Menstrua, by Electricity."

As soon as it was discovered that a power generated by the Voltaic
pile was capable of destroying elective affinity in the vicinity
of the metallic points, it seemed reasonable to suppose, that
the same power might also destroy it, or at least suspend its
operation, throughout the whole of the circuit. The truth of such
a supposition was at once placed beyond all doubt by the following
very striking experiment.

Three tubes, the first containing a solution of _sulphate of
potash_, the second a weak solution of _ammonia_, and the third,
_pure water_, each being connected with the other in the usual
manner by amianthus, were arranged in relation to the pile, as
follow:--the _sulphate of potash_ was placed in contact with the
negatively electrified point, the _pure water_ with the positively
electrified point, while the solution of _ammonia_ was made the
middle link of the conducting chain; so that no sulphuric acid
could pass to the positive point in the distilled water, without
passing through the ammoniacal solution.

In less than five minutes after the electric current had been
completed, it was found, by means of litmus paper, that acid was
in the act of collecting around the positive point; and in half an
hour the result was sufficiently distinct for accurate examination.

Other experiments were made with a solution of lime, and with weak
solutions of potash and soda, and the results were analogous.
Muriatic acid, from muriate of soda, and nitric acid, from nitrate
of potash, were also transmitted through concentrated alkaline
menstrua, under similar circumstances, and with like effects.

Davy also made several experiments on the transition of alkaline
and acid matter, through different neutro-saline solutions, the
results of which were exactly such as theory would have anticipated.

In conducting, however, these experiments of electrical
transference, there would appear to be one condition essential to
their success, viz. that the solution contained in the intermediate
vessel should not be capable of forming an insoluble compound with
the substance transmitted through it: thus, for example, Davy
found that _strontia_ and _baryta_ passed, like the other alkaline
substances, very readily through muriatic and nitric acids;
and _vice versâ_, that these acids passed with equal facility
through aqueous solutions of the earths in question; but when it
was attempted to pass _sulphuric_ acid through the same earthy
solutions, or to pass the earths through the sulphuric acid, that
then the results were of a very different character: the sulphuric
acid, in its passage through the barytic solution, was arrested in
its progress by the earthy body, and falling down as an insoluble
compound with it, was carried out of the sphere of the electrical
action, by which the power of transfer was destroyed. The same
phenomena occurred whenever he attempted to pass muriatic acid
through a solution of sulphate of silver. We now come to the next
division--viz. "Some general Observations on these Phenomena, and
on the mode of Decomposition and Transition."

Davy considers that it will be a general expression of the facts
relating to the changes and transitions by electricity, to say,
that "hydrogen, the alkaline substances, the metals, and certain
oxides, are attracted by negatively electrified, and repelled by
positively electrified metallic surfaces; and on the contrary, that
oxygen and acid substances are attracted by positively electrified,
and repelled by negatively electrified metallic surfaces."
And moreover, that these "attractive and repulsive forces are
sufficiently energetic to destroy or suspend the usual operation of
elective affinity."

Amidst all these wonderful phenomena, that perhaps which excites
our greatest astonishment is the fact of the transfer of ponderable
matter to a considerable distance, through intervening substances,
and in a form that escapes the cognizance of our senses! Upon
this question, Davy offers the following remarks:--"It is," says
he, "very natural to suppose, that the repellent and attractive
energies are communicated from one particle to another particle of
the same kind, so as to establish a conducting chain in the fluid;
and that the locomotion takes place in consequence: thus, in all
the instances in which I examined alkaline solutions through which
acids had been transmitted, I always found acid in them, as long
as any acid matter remained at the original source. In time, by
the attractive power of the positive surface, the decomposition
and transfer undoubtedly become complete; but this does not affect
the conclusion. In cases of the separation of the constituents of
water, and of solutions of neutral salts forming the whole of the
chain, there may possibly be a succession of decompositions and
recompositions throughout the fluid."

We are next brought to a very important point in the enquiry--viz.
"The consideration of the General Principles of the chemical
changes produced by Electricity."

The experiment of Mr. Bennett, already alluded to, had shown that
many bodies, when brought into contact, and afterwards separated
from each other, exhibited signs of opposite states of electricity:
but it is to the investigations of M. Volta that we are indebted
for the clear developement of the fact; for he has distinctly
proved it in the case of copper and zinc, and other metallic
combinations, and he supposed that it might also take place with
regard to metals and fluids.

In a series of experiments, made in the year 1801, on the
construction of electrical combinations, by means of alternations
of single metallic plates, and different strata of fluids, as
explained upon a former occasion,[62] Davy had observed that, when
acid and alkaline solutions were employed as the elements of these
Voltaic combinations, the alkaline solutions always received
the electricity from, and the acid always transmitted it to the
metal. These principles seem to bear an immediate relation to those
general phenomena of decomposition and transfer, which have been
the subject of the preceding details.

  [62] Page 223.

In the most simple case of electrical action, the alkali which
receives electricity from the metal would necessarily, on being
separated from it, appear _positive_; whilst the acid, under
similar circumstances, would be _negative_; and these bodies having
respectively, with regard to the metal, that which may be called a
positive and a negative electrical energy, in their repellent and
attractive functions, would seem to be governed by the common laws
of electrical attraction and repulsion; the body possessing the
positive energy being repelled by positively electrified surfaces,
and that possessing the negative influence following the contrary
order.

Davy made a number of experiments with the view of elucidating this
idea, and of extending its application; and, in all cases, their
results tended, in a most remarkable manner, to confirm the analogy.

He proceeded, by means of very delicate instruments, to ascertain
the electrical states of single insulated acid and alkaline
solutions, after their contact with metals; but the sources of
errors were so numerous, as to render the results far from being
satisfactory; but in experiments on dry and solid bodies, the
embarrassments arising from evaporation, chemical action, &c. did
not occur. When perfectly dry oxalic, succinic, benzoic, or boracic
acid, either in the form of powder or crystals, were touched upon
an extended surface with a plate of copper, insulated by a glass
handle, the copper was found positive, the acid negative. When
again metallic plates were made to touch dry lime, strontia, or
magnesia, they became negative: in these latter experiments the
effect was exceedingly satisfactory and distinct; a single contact
upon a large surface being sufficient to communicate a considerable
charge.

Numerous other trials were made, and the results confirmed the
principle; and moreover proved, as might have been expected, that
bodies possessing electrical conditions with regard to one and the
same body, possessed them with regard to each other: for instance,
a dry piece of lime became positively electrical by repeated
contact with crystals of oxalic acid.

These results led him to reason more fully upon the "Relations
between the Electrical energies of bodies and their Chemical
affinities."

As the chemical attraction subsisting between two bodies seems
to be destroyed by giving to one of them an electrical condition
opposite to that which it naturally possesses; and since the
substances that combine chemically, as far as can be ascertained,
exhibit opposite states of electricity, the relations between
this energy and chemical affinity would appear to be sufficiently
evident to warrant the conclusion at which Davy arrived, viz. that
"the combinations and decompositions by electricity were referable
to the law of electrical attractions and repulsions;" from which
he advanced to the still more important step--"that chemical and
electrical attractions were produced by the same cause, acting in
one case on particles, in the other on masses."

From these views, he is led to propose the electrical powers,
or the forces required to disunite the elements of bodies, as
a test or measure of the intensity of chemical attraction. An
accurate investigation into this connexion, which may be called the
_Electro-dynamic_ relations of bodies to their combining masses or
proportional numbers, would be the first step towards fixing the
science of Chemistry on the permanent foundation of the Mathematics.

If, then, the power of electrical attraction and repulsion be
identified with chemical affinity, or rather, if both be dependent
upon the same cause, it will follow that two bodies which are
naturally in opposite electrical states, may have these states
sufficiently exalted to give them an attractive power superior to
the cohesive force opposed to their union; when a combination will
take place which will be more or less energetic, as the opposed
forces are more or less equally balanced. Again, when two bodies,
repellent of each other, act upon a third with different degrees
of the same electrical energy, the combination will be determined
by the degree; or, if bodies having different degrees of the same
electrical energy with respect to a third, have likewise different
energies with respect to each other, there may be such a balance of
attracting and repelling forces as to produce a triple compound;
and by the extension of this reasoning, complicated chemical union
may be easily explained.

Whenever bodies brought by artificial means into a high state of
opposite electricities are made to restore the equilibrium, heat
and light are the common consequences. It is perhaps an additional
circumstance in favour of the theory to state, that heat and light
are likewise the results of all intense chemical action. And as
in certain forms of the Voltaic battery, where large quantities
of electricity of low intensity act, heat without light is
produced; so in slow chemical combinations there is an increase of
temperature without any luminous appearance.

The effect of heat in producing combination may be easily explained
according to these ideas; it not only gives more freedom of motion
to the particles, but in a number of cases it seems to exalt the
electrical energies of bodies:--glass, the tourmaline, sulphur, and
some others, afford familiar instances of this latter species of
energy.

In general, when the different energies are strong and in perfect
equilibrium, the combination ought to be quick, the heat and light
intense, and the new compound in a neutral state. This would seem
to be the case in the combination of oxygen and hydrogen, which
form water, a body apparently neutral in electrical energy to most
others; and also in the circumstances of the union of the strong
alkalies and acids. But where one energy is feeble, and the other
strong, all the effects must be less vivid; and the compound,
instead of being neutral, ought to exhibit the excess of the
stronger energy.

The grand principle thus developed may enable us to obtain
new and useful indications of the composition of bodies, by
ascertaining the character of their electrical energies; and we
now find, in most modern works of Chemistry, that bodies are
arranged according to their natural electrical relations; and are
said to be ELECTRO-POSITIVE, or ELECTRO-NEGATIVE, according to
their polarities. The advantage of such an arrangement must be
freely acknowledged, for it has been the means of establishing
analogies[63] of the utmost importance in chemistry, of which I
shall adduce some striking examples in a subsequent part of the
present work, when I shall endeavour to offer a general view of
the revolution which chemical science has undergone during the
investigations of Davy, and contemporary philosophers.

  [63] It will be sufficient for my present purpose to point out
  those existing between _Chlorine_, _Iodine_, and _Bromine_.

After some further enquiries into the theory of the Voltaic
pile,[64] to which an allusion has been already made, the author
offers additional reasons for supposing the decomposition of the
chemical menstrua essential to the continued electro-motion of the
pile; and if the fluid medium could be a substance incapable of
decomposition, there is every reason to believe the equilibrium
would be restored, and the motion of the Electricity cease. Having
shown the effects of _induction_, in increasing the electricity
of the opposite plates, he arrives at the important conclusion,
that in a Voltaic arrangement the _intensity of the Electricity
increases with the number, but the quantity with the size of
the plates_. A theory which was subsequently confirmed by the
experiments of Mr. Children.

  [64] See page 226.

The paper concludes with "some general illustrations and
applications of the foregoing facts and principles," and which
the author thinks will readily suggest themselves to the
philosophical enquirer. They offer, for instance, very easy
methods of separating acid and alkaline matter, where they exist
in combination in mineral substances; and, in like manner, they
suggest the application of electrical powers for effecting the
decomposition of animal and vegetable bodies.

On exposing a piece of muscular fibre to the action of the battery,
he found that potash, soda, ammonia, lime, and oxide of iron, were
evolved on the negative side, and the three mineral, together with
the phosphoric, acids, were given out on the positive side.

A laurel leaf, similarly treated, yielded to the negative vessel
resin, alkali, and lime; while in the positive one there collected
a clear fluid, which had the smell of peach-blossoms, and which,
when neutralized by potash, gave a blue-green precipitate to a
solution of sulphate of iron; so that it must have contained
_Prussic Acid_.

A small plant of mint, in a state of healthy vegetation, on being
made the medium of connection in the battery, yielded potash
and lime to the water negatively electrified, and acid to that
positively electrified. The plant recovered after the process; but
a similar one, that had been electrified during a longer period,
faded and died.

These facts would seem to show, that the electrical powers of
decomposition even act upon vegetable matter in its living
condition; and phenomena are not wanting to show that they operate
also on the system of living animals. When the fingers, after
having been carefully washed with pure water, are brought in
contact with this fluid in the positive part of the circuit, acid
matter is rapidly developed, having the character of a mixture of
muriatic, phosphoric, and sulphuric acids; and if a similar trial
be made in the negative part, fixed alkaline matter is as quickly
developed.[65]

  [65] Reflecting upon this and similar facts, it has occurred
  to me that Voltaic electricity might be applied for removing
  the blue colour in the skin, occasioned by the internal use of
  nitrate of silver. I hope to be able very shortly to submit this
  theory to the test.

Davy thinks that the acid and alkaline taste produced upon the
tongue during galvanic experiments, depends upon the decomposition
of the saline matter contained in the living animal substance, and
perhaps in the saliva; and he farther observes that, as acid and
alkaline substances are thus evidently capable of being separated
from their combinations in living systems by electrical powers,
there is reason to believe that, by converse methods, they might
also be introduced into the animal economy, or made to pass
through the animal organs; and the same thing may be supposed of
metallic oxides; and that these ideas ought to lead to some new
investigations in Medicine and Physiology.

He thinks it by no means improbable, that the electrical
decomposition of the neutral salts, in different cases, may
admit of economical applications; and that well-burnt charcoal
and plumbago, or charcoal and iron, might be made the exciting
powers for such a purpose. Such an arrangement, if erected upon a
scale sufficiently extensive, with the medium of a neutro-saline
solution, would, in his opinion, produce large quantities of acids
and alkalies with very little trouble or expense.

Alterations in chemical equilibrium are constantly taking place in
Nature, and he thinks it probable that the electric influence, in
its faculties of decomposition and transference, may considerably
interfere with the chemical changes occurring in different parts of
our system.

The electrical appearances which precede earthquakes and volcanic
eruptions, and which have been described by the greater number of
the observers of these awful events, admit also of easy explanation
on the principles that have been stated.

Besides the cases of sudden and violent change, he considers there
must be constant and tranquil alterations, of which electricity,
produced in the interior strata of the globe, is the active
cause: thus, where _pyritous_ strata and strata of _coal-blende_
occur,--where the pure metals or the sulphurets are found in
contact with each other, or with any conducting substances,--and
where different strata contain different saline menstrua, he thinks
electricity must be continually manifested; and it is probable that
many mineral formations have been materially influenced, or even
occasioned, by its agencies.

In an experiment which he performed of electrifying a mixed
solution of the muriates of iron, copper, tin, and cobalt,
contained in a positive vessel, all the four oxides passed along
the connecting asbestus into a positive vessel filled with
distilled water, while a yellow metallic crust formed on the wire,
and the oxides arranged themselves in a mixed state around the base
of it.

In another experiment, in which carbonate of copper was diffused
through water in a state of minute division, and a negative wire
was placed in a small perforated cube of zeolite in the water,
green crystals collected round the cube; the particles not being
capable of penetrating it.

By a multiplication of such instances, Davy remarks, that the
electrical power of transference may be easily conceived to apply
to the explanation of some of the principal and most mysterious
facts in geology;[66] and by imagining a scale of feeble powers,
it would be easy to account for the association of the insoluble
metallic and earthy compounds containing acids.

  [66] During the contentions of the Neptunists and Plutonists,
  alluded to in a former part of this work, specimens were produced
  exhibiting the intermixture of mineral bodies, which was
  completely hostile to all theory. These anomalies now receive a
  plausible explanation from the agencies of Voltaic electricity.

"Natural electricity," observes our philosopher, "has hitherto been
little investigated, except in the case of its evident and powerful
concentration in the atmosphere. Its slow and silent operations in
every part of the surface will probably be found more immediately
and importantly connected with the order and economy of nature;
and investigations on this subject can hardly fail to enlighten
our philosophical systems of the earth, and may possibly place new
powers within our reach."

Thus concludes one of the most masterly and powerful productions
of scientific genius. I may perhaps have been considered prolix in
recording the progressive researches by which he arrived at his
results; but let it be remembered, that the great fame of Davy,
as an experimental philosopher, rests upon this single memoir;
and though the secondary results to be hereafter considered, may
be more dazzling to ordinary minds, yet in the judgment of every
scientific observer, they must appear far less glorious than the
discovery of the primitive laws. Let me ask whether Sir Isaac
Newton does not deserve greater fame for his invention of fluxions,
than for the calculations performed by the application of them? I
do not hesitate in comparing these great philosophers, since each
has enlightened us by discoveries alike effected by means invented
by himself. Not only did both unlock the caskets of Nature, but
they had the superior merit of planning and constructing the key.

I challenge those, who have carefully followed me through the
details of the preceding memoir, to show a single instance in
which accident, so mainly contributory to former discoveries in
electricity, had any share in conducting its author to truth.
Step by step did he, with philosophic caution and unwearied
perseverance, unfold all the particular phenomena and details of
his subject; his genius then took flight, and with an eagle's eye
caught the plan of the whole.--A new science has been thus created;
and so important and extensive are its applications, so boundless
and sublime its views, that we may fairly anticipate the fulfilment
of those prophetic words of Dr. Priestley, who, in the preface
to his History of Electricity,[67] exclaims--"Electricity seems
to be giving us an inlet into the internal structure of bodies,
on which all their sensible properties depend. By pursuing this
new light, therefore, the bounds of natural science may possibly
be extended beyond what we can now form any idea of. New worlds
may open to our view, and the glory of the great Sir Isaac Newton
himself, and all his contemporaries, be eclipsed by a new set of
philosophers, in quite a new field of speculation. Could that great
man revisit the earth, and view the experiments of the present race
of electricians, he would be no less amazed than Roger Bacon, or
Sir Francis, would have been at his." In our turn we may ask, what
would be the astonishment--what the delight of Dr. Priestley, could
he now witness the successful results of Voltaic research?--and
what would he say of that mighty genius who has demonstrated the
relations of electrical energy to the general laws of chemical
action?[68] It was his good fortune to have witnessed the discovery
which identified electricity with the lightning of the thunder
cloud: what would he have said of that which identified it with
the magnetism of the earth! Of this at least we may be certain,
that he would have expunged from his history the passage in which
he observes--"Electrical discoveries have been made so much by
accident, that it is more the powers of nature, than of human
genius, that excite our wonders with respect to them."

  [67] The History and Present State of Electricity; by Jos.
  Priestley, LL.D. F.R.S., &c. London, 1795.

  [68] Dr. Priestley augured much from the talents of Davy. After
  the publication of his first paper on Galvanism, he wrote to him
  from America, and expressed the pleasure he felt on finding his
  favourite subject in such able hands. Priestley died in 1804, and
  therefore did not witness Davy's success.




CHAPTER VII.

   The unfair rivalry of Philosophers.--Bonaparte the Patron
   of Science.--He liberates Dolomieu.--He founds a Prize for
   the encouragement of Electric researches.--His letter to the
   Minister of the Interior.--Proceedings of the Institute.--The
   Prize is conferred on Davy.--The Bakerian Lecture of 1807.--The
   Decomposition of the Fixed Alkalies--Potassium--Sodium.--The
   Questions to which the discovery gave rise.--Interesting
   Extracts from the Manuscript Notes of the Laboratory.--Potash
   decomposed by a chemical process.--Letters to Children, and
   Pepys.--The true nature of Potash discovered.--Whether Ammonia
   contains Oxygen.--Davy's severe Illness.--He recovers and
   resumes his labours.--His Fishing Costume.--He decomposes the
   Earths.--Important views to which the discovery has led.


It must be confessed that there has too frequently existed amongst
philosophers a strange and ungenerous disposition to undervalue
the labours of their contemporaries. If a discovery be made, its
truth and importance are first questioned; and should these be
established, then its originality becomes a subject of dispute.

Truth, although she may have been rarely held fast, has been
frequently touched[69] in the dark: it is not extraordinary,
therefore, that evidence may be often strained from the writings of
philosophers in support of prior claims to late discoveries; but
upon a candid review, these loose statements, or obscure hints,
will generally be found wholly destitute of the pretensions which
an unfair spirit of rivalry has too often laboured to support. Many
of such hints, indeed, so far from advancing the progress of truth,
had never even attracted notice, until after the discoveries to
which they have been supposed to relate.

  [69] A most remarkable illustration of this fact occurs in the
  history of Locke, who certainly came as near to an important
  discovery as any philosopher who ever caught a glimpse of a truth
  without seizing it; but his statement did not, in any degree,
  hasten the developement of that new branch of science which was
  reserved for the genius of Dr. Black to investigate, and who a
  century later, by the discovery of fixed air, changed the whole
  face of Chemistry. The passage to which I allude is extracted
  from the Life by Lord King, and is so curious, that I shall give
  it a place in this note. "M. Toinard produced a large bottle of
  Muscat: it was clear when he set it on the table; but when he
  had drawn out the stopper, a multitude of little bubbles arose,
  and swelled the wine above the mouth of the bottle. It comes
  from this, that the air, which was included and disseminated
  in the liquor, had liberty to expand itself, and so to become
  visible, and, being much lighter than the liquor, to mount with
  great quickness.--_Quere_, Whether this be air new generated, or
  whether the springy particles of air in the fruit, out of which
  these fermenting liquors are drawn, have, by the artifice of
  Nature, been pressed close together, and there by other particles
  fastened and held so; and whether fermentation does not loose
  these bands, and give them liberty to expand themselves again?
  Take a bottle of fermenting liquor, and tie a bladder on the
  mouth.--_Quere_, How much new air will it produce; and whether
  this has the quality of common air?"

  Another instance equally illustrative of the manner in which
  important truths will sometimes elude notice, even after Science
  has approached so near as to touch them, is presented in the
  history of the Barometer. Toricelli, the pupil of Galileo, while
  reflecting upon the phenomenon which had so greatly perplexed
  his master, viz. that water could not be raised above thirty-two
  feet in the body of a pump, rightly conjectured that the water,
  under such circumstances, was not _drawn_, but _pushed up_ into
  the barrel, and that it could only be so pushed up by the force
  of the atmosphere. It then occurred to him, that if mercury were
  used instead of water, being heavier, it would not be pushed
  up so high by the weight of the air. So, taking a glass tube
  of about three feet in height, made air-tight at one end, he
  first filled it completely with quicksilver, and then closing it
  with his finger, reversed it in a basin containing that metal;
  when he had the gratification of seeing the liquid in the tube
  descend, as he had anticipated. Here then was the discovery of
  the BAROMETER; but it was reserved for another to find out that
  such an instrument had been actually invented. Pascal first made
  the remark, that the inference of Toricelli, if true, might
  be confirmed by carrying the mercurial tube to a considerable
  elevation; when the atmospheric column being diminished, that of
  the mercury, which was supposed to be its balance, ought likewise
  to be shortened in a corresponding proportion. It followed
  then, that a measure of the weight of the atmosphere, in all
  circumstances, had been obtained, and consequently that of the
  height of any place to which the instrument could be carried. In
  this manner was a discovery completed, which had for ages escaped
  the greatest philosophers who had made the nearest approaches to
  its developement.

Although the importance of Davy's Electro-chemical discoveries
could not for a moment be doubted; their claims to originality,
it would seem, were not admitted without some question. The works
of Ritter and Winterl, amongst many others, were quoted to show
that these philosophers had imagined or anticipated the relation
between electrical powers and chemical affinities; but Davy very
fairly observes, in a paper read before the Royal Society in 1826,
that in the obscurity of the language and metaphysics of both those
gentlemen, it is difficult to say what may not be found. In the
ingenious though wild views of Ritter, there are hints which
may more readily be considered as applying to _Electro-magnetism_
than to _Electro-chemistry_; while Winterl's _Miraculous Andronia_
might, with as much propriety, be considered as a type of all the
chemical substances that have been since discovered, as his view
of the antagonist powers (the acid and base) be regarded as an
anticipation of the _Electro-chemical_ theory.

It would be worse than useless to speak of other works, which refer
the origin of Electro-chemistry to Germany, Sweden, and France,
rather than to Italy and England; and which attribute some of the
views first developed by Davy, to philosophers who have not, nor
ever could have made any claim of the kind, since their experiments
were actually not published until many years after 1806, the date
of the Bakerian Lecture.

With regard to the judgment of posterity upon these points, but
little apprehension can be entertained. I well remember, in a
conversation with Davy, he observed, that "a philosopher might
generally discover how his labours would be appreciated in after
ages, from the opinion entertained of them by contemporary
foreigners, who, being unbiassed by circumstances of personality,
will reduce every object to its just proportions and value."

If we acknowledge the truth of such a standard, and submit the
posthumous fame of Davy to its measure, where is the philosopher,
in our times, whose name is destined to attain a higher eminence
in the history of Science? Let the reader only recall to his
recollection the bitter animosity which France and England
mutually entertained towards each other in the year 1807, and he
will be able to form some idea of the astounding impression which
the Bakerian Lecture must have produced on the Savans of Paris,
when, in despite of national prejudice and national vanity, it
was crowned by the Institute of France with the prize of the
First Consul! Thus did the Voltaic battery, in the hands of the
English chemist, achieve what all the artillery of Britain could
never have produced--A SPONTANEOUS AND WILLING HOMAGE TO BRITISH
SUPERIORITY!--But let not this observation convey the slightest
idea of disrespect, or be supposed to encourage any feeling to the
disparagement of the chemists of France; on the contrary, it is
even a question not readily answered, to which party the triumph
fairly belongs,--to him who won the laurel crown, or to those who
so nobly placed it on his brow? They have set an example to future
ages, which may as materially advance the progress of science,
as the researches which called it forth:--they have shown, to
adopt the language of an eloquent writer, that "the Commonwealth
of Science is of no party, and of no nation; that it is a pure
Republic, and always at peace. Its shades are disturbed neither by
domestic malice nor foreign levy; they resound not with the cries
of faction or of public animosity. Falsehood is the only enemy
their inhabitants denounce; Truth, and her minister Reason, the
only leaders they follow."

I shall avail myself of this opportunity to introduce the Report
drawn up by M. Biot, and made in the name of a Commission
appointed by the Institute to accomplish the intention of
Bonaparte, who, when First Consul, founded prizes for important
discoveries in Electricity or Galvanism.

It is an opinion very generally received, that despotism is hostile
to the progress of Philosophy--that the suspicion natural to
tyranny, and the fear that light should expose its deformity, have,
under such circumstances, inspired a dread of any thing approaching
to freedom of enquiry. The conduct of Napoleon, not only during his
Consulate, but even after he had assumed the Purple, is in direct
opposition to such an opinion. Now that the excitements of national
hostility have subsided, and the asperity of our feelings towards
that extraordinary man has been softened by time and prosperity, we
are enabled to discern the bright and sunny spots in his character.

Not to mention the immense plans which his genius suggested for the
internal improvement of France, the annals of the Institute would
furnish innumerable proofs of the zeal with which he encouraged
Science, and promoted its interests.

His liberation of Dolomieu from the dungeons of Tarentum was an
act not only remarkable for the considerate regard it displayed
for Science, but for the spirit and eagerness with which it was
effected. The French Government had repeatedly made the most urgent
demands for the liberty of one who had reflected so much credit
on his country;--the Danes had also directed the interference of
their Minister, and the King of Spain had added his solicitations
in vain:--no sooner, however, had the astonishing campaign which
terminated by the victory of Marengo, completely established the
French Republic, than Bonaparte, in making peace with Naples,
stipulated for the immediate deliverance of Dolomieu, as the first
article of the treaty.

The following letter from Bonaparte, addressed to the Minister of
the Interior, and by him transmitted to the Institute, expresses
the intentions of the First Consul, in founding prizes for
important discoveries in Electricity or Galvanism.

    "I intend, Citizen Minister, to found a prize, consisting of a
    Medal of three thousand francs, (about one hundred and twenty
    pounds sterling,) for the best experiment which shall be made in
    the course of each year, on the Galvanic fluid.

    "For this purpose, the Memoirs containing the details of the said
    experiments shall be sent before the First of _Fructidor_, to the
    Class of the Mathematical and Physical Sciences, which in the
    complimentary days shall adjudge the prize to the author of that
    experiment which has been most useful to the progress of Science.

    "I also desire to give, by the way of encouragement, the sum of
    sixty thousand francs to the person who, by his experiments and
    discoveries, shall, according to the opinion of the Class, advance
    the knowledge of Electricity and Galvanism as much as Franklin and
    Volta did.[70]

    "Foreigners of all nations are admitted to the competition.

    "I beg you will make known these dispositions to the President of
    the First Class of the National Institute, that it may give to
    these ideas such developement as may appear proper; my particular
    object being to encourage philosophers, and to direct their
    attention to this part of philosophy, which, in my opinion, may
    lead to great discoveries.

    "(Signed)  BONAPARTE."


  [70] "À celui qui, par ses expériences et ses découvertes, _fera
  à faire à l'Electricité et au Galvanisme un pas comparable à
  celui qu'ont fait faire à ces Sciences Franklin et Volta_."

  My French correspondent adds, "Ces soixantes mille francs n'ont
  pas été adjugés, _le pas n'ayant point été fait_."

Upon the presentation of this letter, a Committee was appointed
to consider the means for accomplishing the intentions of the
First Consul; and after expatiating upon the extensive agencies of
Electricity, their Report concludes in the following manner:--

    "To fulfill the intention of the First Consul, and to give to the
    competition all the solemnity which the importance of the object,
    the nature of the Prize, and the character of the Founder require,
    the Commissioners unanimously propose as follows:

    "The Class of the Mathematical and Physical Sciences of the
    National Institute opens the general competition required by the
    First Consul.

    "All the learned of Europe, and the Members and Associates of the
    Institute, are admitted to the competition.

    "The Class does not require that the Memoirs should be immediately
    addressed to it. Every year it will crown the author of the best
    experiments which shall come to its knowledge, and which shall have
    advanced the progress of the science.

    "The present report, containing the letter of the First Consul,
    shall be printed, and serve as a programme.

    "Done at the National Institute, Messidor 11, year 10.

    "(Signed) LAPLACE, HALLE, COULOMB,
    HAUY. BIOT, Reporter."

It was not until twelve months after the publication of his
first Bakerian Lecture, that Davy received the intelligence
that the prize of three thousand francs had been awarded him by
the Institute of France, for his discoveries announced in the
Philosophical Transactions for the year 1807.

Mr. Poole, in a late communication, informs me that he was in
London soon after the letter communicating this gratifying
intelligence had been received from France; and that Davy, upon
showing it to him, observed, "Some people say I ought not to
accept this prize; and there have been foolish paragraphs in the
papers to that effect; but if the two countries or governments
are at war, the men of science are not. That would, indeed, be
a civil war of the worst description: we should rather, through
the instrumentality of men of science, soften the asperities of
national hostility."

After Davy had been elected Secretary to the Royal Society, he
appears to have been confined to town during the autumn of 1807,
when he wrote the following letter.


    TO THOMAS POOLE, ESQ.

    August 28th, 1807.

    MY DEAR POOLE,

    I am obliged to be in the neighbourhood of town during the greater
    part of the summer, for the purpose of correcting the press for
    the Philosophical Transactions.

    I made a rapid journey into Cornwall for the sake of seeing my
    family; and it was not in my power, had I received your letter at
    Lyme, to have accepted your kind invitation.

    If C---- is still with you, will you be kind enough to say to him,
    that I wrote nearly a week ago two letters about lectures, and not
    knowing where he was, I addressed them to him at different places?
    I wish very much he would seriously determine on this point. The
    Managers of the Royal Institution are very anxious to engage him;
    and I think he might be of material service to the public, and
    of benefit to his own mind, to say nothing of the benefit his
    purse might also receive. In the present condition of society,
    his opinions in matters of taste, literature, and metaphysics,
    must have a healthy influence; and unless he soon become an actual
    member of the living world, he must expect to be hereafter brought
    to judgment 'for hiding his light.'

    The times seem to me to be less dangerous, as to the immediate
    state of this country, than they were four years ago. The extension
    of the French Empire has weakened the disposable force of France.
    Bonaparte seems to have abandoned the idea of invasion; and if our
    Government is active, we have little to dread from a maritime war,
    at least for some time. Sooner or later, our Colonial Empire must
    fall in due time, when it has answered its ends.

    The wealth of our island must be diminished, but the strength of
    mind of the people cannot easily pass away; and our literature,
    our science, our arts, and the dignity of our nature, depend little
    upon our external relations. When we had fewer colonies than Genoa,
    we had Bacons and Shakspeares.

    The wealth and prosperity of the country are only the _comeliness_
    of the body--the fulness of the flesh and fat;--but the spirit is
    independent of them; it requires only muscle, bone, and nerve, for
    the true exercise of its functions. We cannot lose our liberty,
    because we cannot cease to _think_; and ten millions of people are
    not easily annihilated.

    I am, my dear Poole, very truly yours,

    H. DAVY.


While the Electro-chemical laws, developed in the last chapter,
are fresh in the recollection of the reader, I shall proceed to
the consideration of his second Bakerian Lecture, which was read
in November 1807; and in which he announces the discovery of the
metallic bases of the fixed alkalies,--a discovery immediately
arising from the application of Voltaic electricity, directed in
accordance with those laws;--thus having, as we have seen in the
first instance, ascended from particular phenomena to general
principles, he now descends from those principles to the discovery
of new phenomena: a method of investigation by which he may be said
to have applied to his inductions the severest tests of truth, and
to have produced a chain of evidence without having a single link
deficient.

Since the account given by Newton of his first discoveries in
Optics, it may be questioned whether so happy and successful an
instance of philosophical induction has ever been afforded as that
by which Davy discovered the composition of the fixed alkalies.
Had it been true, as was most unjustly insinuated at the time,
that the discovery was accidentally effected by the high power of
the apparatus placed at his disposal, his claims to our admiration
would have assumed a very different character: in such a case,
he might be said to have forced open the sanctuary of Nature by
direct violence, instead of having discovered and touched the
secret spring by which its portals were unclosed. The justice of
these remarks will best appear in the examination of his memoir:
the highest eulogy that can be conferred on its author will be a
faithful and plain history of its contents.

It will be remembered that, in his preceding lecture of 1806, he
had described a number of decompositions and chemical changes
produced in substances of known composition, by the powers of
electricity, and that in all such cases there invariably subsisted
an attraction between oxygen and the _positive_ pole, and between
inflammable matter and the _negative_ pole of the pile: thus,
in the decomposition of water, its oxygen was transferred to
the former, and its hydrogen to the latter. Furnished with such
data, Davy proceeded to submit a fixed alkali to the most intense
action of the Voltaic apparatus, well convinced that, should the
electrical energy be adequate to effect its decomposition, the
elements would be transferred, according to this general law, to
their respective poles.

His first attempts were made on solutions of the alkalies; but,
notwithstanding the intensity of the electric action, the
water alone underwent decomposition, and oxygen and hydrogen
were disengaged with the production of much heat, and violent
effervescence. The presence of water thus appearing to prevent the
desired decomposition, potash, in a state of igneous fusion, was
in various ways submitted to experiment; when it was evident that
combustible matter of some kind, burning with a vivid light, was
given off at the negative wire. After numerous trials, during the
progress of which the difficulties which successively arose were
as immediately combated by ingenious manipulation, a small piece
of potash sufficiently moistened, by a short exposure to the air,
to give its surface a conducting power, was placed on an insulated
disc of platina, connected with the negative side of the battery in
a state of intense activity, and a platina wire communicating with
the positive side, was at the same instant brought into contact
within the upper surface of the alkali.--Mark what followed!--A
series of phenomena, each of which the reader will readily
understand as it is announced,--for it will be in strict accordance
with the laws which Davy had previously established:--the potash
began to fuse at both its points of electrization: a violent
effervescence commenced at the upper, or positive surface; while
at the lower, or negative one, instead of any liberation of
elastic matter, which would probably have happened had hydrogen
been an element of the alkaline body, small globules, resembling
quicksilver, appeared, some of which were no sooner formed than
they burnt with explosion and bright flame.--What must have been
the sensations of Davy at this moment!--He had decomposed potash,
and obtained its base in a metallic form.

The gaseous matter developed, during the experiment, at the
positive pole of the apparatus, he very shortly identified as
oxygen. To collect, however, the metallic matter, in a quantity
sufficient for a satisfactory examination, was by no means so easy;
for, like the _Alkahest_ imagined by the Alchemist, it acted more
or less upon every body to which it was exposed; and such was its
attraction for oxygen, that it speedily reverted to the state of
alkali by recombining with it.

After various trials, however, it was found that recently distilled
naphtha presented a medium in which it might be preserved and
examined, since a thin transparent film of this fluid, while it
defended the metal from the action of the atmosphere, did not
oppose any obstacle to the investigation of its physical properties.

Thus provided, he proceeded to enquire into the nature of the
new and singular body, to which he afterwards gave the name of
POTASSIUM, and which may be described as follows.

Its external character is that of a white metal, instantly
tarnishing by exposure to air; at the temperature of 70° Fah.
it exists in small globules, which possess the metallic lustre,
opacity, and general appearance of quicksilver; so that when a
globule of the latter is placed near one of the former, the eye
cannot discover any difference between them: at this temperature,
however, the metal is not perfectly fluid; but when gradually
heated, it becomes more so,--and at 150°, its fluidity is so
perfect that several globules may be easily made to run into
one. By reducing its temperature, it becomes, at 50°, a soft and
malleable solid, which has the lustre of polished silver, and is
soft enough to be moulded like wax. At about the freezing point of
water it becomes hard and brittle, and exhibits, when broken, a
crystallized structure of perfect whiteness, and of high metallic
splendour. It is also a perfect conductor both of electricity and
heat. Thus far, then, it fulfills every condition of a metal;
but an anomaly of a most startling description has now to be
mentioned--the absence of a quality which has been as invariably
associated with the idea of a metal, as that of lustre, viz. great
specific gravity. Whence a question has arisen, whether, after
all, the alkaline base can with propriety be classed under that
denomination? Instead of possessing that ponderosity which we
should have expected in a body otherwise metallic, it is so light
as not only to swim upon the surface of water, but even upon that
of naphtha, by far the lightest liquid in nature. Davy, however,
very justly argues, that low specific gravity does not offer a
sufficient reason for degrading this body from the rank of a metal;
for amongst those which constitute the class, there are remarkable
differences with respect to this quality; that platina is nearly
four times as heavy as tellurium. In the philosophical division
of bodies into classes, the analogy between the greater number of
properties must always be the foundation of arrangement.[71]

  [71] The propriety, and even the necessity, of such a compact
  become daily more apparent, as our knowledge of bodies
  extends. If we were to degrade a substance from its class, in
  consequence of the absence of some one quality which enters
  into its more perfect examples, we should soon find ourselves
  involved in paradoxes.--What idea, for instance, could we form
  of an acid?--Its sourness?--Prussic Acid--Arsenious Acid, are
  not sour.--Its tendency to combine with an alkaline or earthy
  base?--If so, sugar is an acid, for it combines with lime. I
  remember a chemist having been exposed to much ridicule from
  speaking of a _sweet_ acid--Why not?

So inseparable however, by long association, are the ideas of
ponderosity and metallic splendour, that the evidence even of the
senses may fail in disuniting them.[72] This is well illustrated
by the following amusing anecdote. Shortly after the discovery of
potassium, Dr. George Pearson happened to enter the laboratory in
the Royal Institution, and upon being shown the new substance, and
interrogated as to its nature, he, without the least hesitation, on
seeing its lustre, exclaimed, "Why, it is metallic, to be sure,"
and then, balancing it on his finger, he added, in the same tone of
confidence, "_Bless me, how heavy it is!_"

  [72] In the language of Darwin, we should say, that the simple
  ideas of weight and lustre, which form the complex idea of a
  metal, have become so indissoluble, that they can no longer be
  separated by volition. The principle admits of many familiar
  illustrations, and is the source of numerous fallacies. When any
  one voluntarily recollects a Gothic window, which he had seen
  some time before, the whole front of the Cathedral occurs to him
  at the same time: in like manner, the taste of a pine-apple,
  though we eat it blindfold, recalls the colour and shape of it.
  Coleridge has made a good remark upon this subject. He says, "It
  is a great law of the imagination, that a likeness in part tends
  to become a likeness of the whole." It is thus that we trace
  images in the fire, castles in the clouds, and spectres in the
  gloom of twilight.

When thrown upon water, potassium instantly decomposes that fluid,
and an explosion is produced with a vehement flame: an experiment
which is rendered more striking if, for water, ice be substituted;
in this latter case, it instantly bums with a bright rose-coloured
flame, and a deep hole is made in the ice, which will afterwards be
found to contain a solution of potash.

It is scarcely necessary to state, that these phenomena depend
upon the very powerful affinity which the metal possesses for
oxygen, enabling it even to separate it from its most subtle
combinations.[73]

  [73] If we are disposed to enter into a more critical examination
  of the subject, we shall find that, although the above is a
  general expression of the change produced, there are subordinate
  actions of a more complicated nature: the metal, in the first
  place, decomposes a portion of the water, in order to combine
  with its oxygen, and form potash, which in its turn has a
  powerful affinity for water; the heat arising from two causes,
  decomposition and combination, is sufficiently intense to produce
  the inflammation. Water is a bad conductor of heat; the globule
  swims exposed to air; a part of which is dissolved by the heated
  nascent hydrogen; and this gas, being capable of spontaneous
  inflammation, explodes and communicates the effect of combustion
  to any of the bases that may be yet uncombined. The manner in
  which the potassium runs along the surface of water may be
  compared to a drop of water on red-hot iron; in the one case the
  hot potassium, in the other the cold water, is enveloped in an
  atmosphere of steam.

One of the neatest modes of showing the production of alkali,
in the decomposition of water by the basis of potash, consists
in dropping a globule of potassium upon moistened paper tinged
with turmeric. At the moment that it comes into contact with the
water, it burns and moves rapidly upon the paper, as if in search
of moisture, leaving behind it a deep reddish-brown trace of its
progress, and acting upon the test paper precisely as dry caustic
potash.

From these observations, the reader will immediately perceive,
that the decomposition of the fixed alkalies has placed in the
hands of the experimentalist a new instrument of research, scarcely
less energetic, or of less universal application, than the power
from which the discovery emanated. Davy observes upon this point,
that "it will undoubtedly prove a powerful agent for analysis,
and having an affinity for oxygen, stronger than any other known
substance, it may possibly supersede the application of electricity
to some of the undecompounded bodies." So strong indeed is its
affinity for oxygen, that it discovers and decomposes the small
quantities of water contained in alcohol and ether; and in the
latter case, this decomposition is connected with an instructive
result. Potash is insoluble in that fluid: when therefore its base
is thrown into it, oxygen is furnished, hydrogen gas disengaged,
and the alkali, as it is regenerated, renders the ether white and
turbid.

But perhaps the most beautiful illustration of its deoxidizing
power is afforded by its action on carbonic acid gas, or fixed
air: when heated in contact with that gas, it catches fire, and by
uniting with its oxygen, becomes potash, while the liberated carbon
is deposited in the form of charcoal.

As I have already exceeded the limits originally prescribed to
myself, I shall not enter into the history of Davy's experiments
on the other fixed alkali, soda, farther than to state that, when
it was submitted to Voltaic action, a bright metal was obtained,
similar in its general characters to potassium, but possessing
sufficiently distinctive peculiarities as to volatility,
fusibility, oxidability, &c. To this body Davy assigned the name of
SODIUM.[74]

  [74] In his Bakerian Lecture of 1810, he informs us that he
  obtains Sodium by heating common salt, which has been previously
  ignited, with Potassium--an immediate decomposition takes place,
  and two parts of Potassium produce rather more than one of Sodium.

In support of the metallic characters of these alkaline bases,
it may be necessary to state that they combine with each other,
and form alloys; the properties and habitudes of which are very
interesting, and are fully described by their discoverer.

No sooner had these results been made known to the scientific
world, than a question arose, both in this country and abroad, as
to the real nature of the bodies which had been thus obtained from
the fixed alkalies, and which presented an aspect so obviously
metallic. At first, it was conjectured by a few, that they might be
compounds of the alkali with the platina used in the experiments;
but this was at once disproved by Davy having obtained the same
results when pieces of copper, silver, gold, plumbago, or even
charcoal, had been employed for completing the Voltaic circuit.

The effect which this and his subsequent discoveries produced, in
revolutionizing the theory of Chemistry, will form an interesting
subject for discussion in a future part of the present work: I
shall therefore only remark in passing, that the fact of oxygen,
the acknowledged principle of acidity, existing in combination with
a metallic base, and imparting to it the properties of an alkali,
was no sooner announced, than its truth was strenuously denied. It
was an attack upon opinions sanctioned by the general suffrage
of the scientific world;--it was, in fact, storming the very
citadel of their philosophy: no wonder, then, that the agitator
should have been assailed with a full cry for his revolutionary
plans.[75] M. Curadau read a paper before the French Institute,
in which he endeavoured to prove, _first_, that the conversion of
the alkalies into metals was not a deoxidation of those bodies,
but a combination of them with new elements;--_secondly_, that the
affinity of the alkaline metals for oxygen was merely a chemical
illusion, occasioned by some body the presence of which had not
been suspected;--_thirdly_, that carbon was one of the elements
of the alkaline metals, since it could be separated from them at
pleasure, or converted into carbonic acid;--and _fourthly_, that if
the specific gravities of the new substances were less than that of
water, it was because hydrogen was associated with carbon in the
combination.

  [75] Many years afterwards, when Davy was travelling on the
  Continent, a distinguished person about a foreign court, enquired
  who and what he was; never having heard of his scientific
  fame. Upon being told that his discoveries had revolutionized
  Chemistry, the courtier promptly replied--"I hate all
  revolutionists--his presence will not be acceptable here."

It is scarcely necessary to state, that the presence of carbon was
readily traced to sources of impurity. The hypothesis which assumed
the existence of hydrogen as an element, was not so easily refuted.
It was espoused by MM. Gay Lussac, Thénard, and Ritter, on the
Continent, and by Mr. Dalton in England. The former derived their
inference from the action of potassium upon ammonia, by which
they obtained a fusible substance that yielded by heat more
hydrogen than the ammonia contained; the latter contended that
potassium and sodium are proved to be _hydrurets_, by the very
process employed for their production; for, since common potash is
a _hydrat_, and oxygen is produced at one surface, and potassium
at the other, by Voltaic action, he conceived that the former
arose from the decomposition of water, and that the hydrogen
must therefore unite with the potash to form potassium. It is a
curious fact, that Berthollet, in the very sentence in which he
insisted upon the excessive quantity of hydrogen disengaged in
his experiment, as a proof that potassium must be a _hydruret_,
should have stated that the addition of water to the residuum was
necessary for obtaining his result. How could it have happened
that he overlooked so obvious a source of hydrogen? Mr. Dalton, as
well as Ritter, considered the low specific gravity as favouring
the idea of their containing hydrogen; but Davy observes that they
are less volatile than antimony, arsenic, and tellurium, and much
less so than mercury. Besides, sodium absorbs much more oxygen
than potassium, and, on the hypothesis of hydrogenation, must
therefore contain more hydrogen; and yet though soda is said to be
lighter than potash, in the proportion of thirteen to seventeen
nearly, sodium is heavier than potassium, in the proportion of
nine to seven at least. On the theory of Davy, this circumstance
is what ought to have been expected. Potassium has a much stronger
affinity for oxygen than sodium, and must condense it much more;
and the resulting higher specific gravity of the combination is
a necessary consequence. In this manner did Davy entangle his
opponents in their own arguments, and establish, in the most
triumphant manner, the truths of his original views.

Thus then was a discovery effected, and at once rendered
complete, which all the chemists in Europe had vainly attempted
to accomplish. The alkalies had been tortured by every variety of
experiment which ingenuity could suggest, or perseverance perform,
but all in vain; nor was the pursuit abandoned until indefatigable
effort had wrecked the patience and exhausted every resource of the
experimentalist. Such was the disheartening, and almost forlorn
condition of the philosopher when Davy entered the field:--he
created new instruments, new powers, and fresh resources; and
Nature, thus interrogated on a different plan, at once revealed her
long cherished secret.

In his Bakerian Lecture, Davy observes, that "a historical detail
of the progress of the investigation of all the difficulties that
occurred, and of the manner in which they were overcome, and of all
the manipulations employed, would far exceed the limits assigned
to a Lecture." But to the chemist, every circumstance, however
minute, connected with a subject of such commanding importance, is
pregnant with interest; I therefore considered it my duty to search
into the archives of the Institution, in the hope that I should
discover some memoranda which might supply additional information.
In examining the Laboratory Register, I have so far succeeded as to
obtain some rough and imperfect notes, which will, to a certain
degree, assist us in analysing the intellectual operations by which
his mind ultimately arrived at the grand conclusion.

It appears from this register that Davy commenced his enquiries
into the composition of potash on the 16th, and obtained his great
result on the 19th of October 1807.[76] His first experiments,
however, evidently did not suggest the truth: he does not appear
to have suspected the nature of the alkaline base until his last
experiment, when the truth flashed upon him in the full blaze of
discovery. His first note, dated the 16th, leads us to infer that
he acted on a solid piece of potash, under the surface of alcohol,
and several other liquids in which the alkali was not soluble; and
that he obtained gaseous matter, which he called at the moment
'_Alkaligen Gas_,' and which he appears to have examined most
closely, without arriving at any conclusion as to its nature. On
the following day, he, for the first time, would seem to have
developed potassium by electric action on potash under oil of
turpentine, for the note records the fact of "_the_ globules giving
out gas by water, which gas _burnt in contact with air_;" and then
follows a query--"Does _it_" (the matter of the globules) "not form
gaseous compounds with ether, alcohol, and the oils?" Here, then,
he evidently imagined, that the matter of the globules, which he
had never obtained from potash, except when acted upon under oil of
turpentine, had formed gaseous compounds with the ether, alcohol,
and oils in his previous experiments, and given origin to that
which he had termed '_Alkaligen Gas_.'

  [76] On the same day he decomposed Soda with somewhat different
  phenomena.

He then leaves the consideration of this gas, and attacks the
unknown globules, which probably did not present any metallic
appearance under the circumstances in which he saw them, for they
must have been as minute as grains of sand. I rather think that he
commenced his examination by introducing a globule of mercury, and
uniting it with a globule of the unknown substance, for his note
says, "Action of the substance on Mercury,--forms with it a solid
amalgam, which soon loses its _Alkaligen_ in the air." And from
the note which succeeds, he evidently considered this _Alkaligen_
(potassium) volatile, as he says "it soon flies off on exposure to
the air."

October 19.--It is probable that, in consequence of the property
which the unknown substance displayed of amalgamating with mercury,
he devised his experiment of the 19th. He took a small glass tube,
about the size and shape of a thimble, into which he fused a
platinum wire, and passed it through the closed end. He then put a
piece of pure potash into this tube, and fused it into a mass about
the wire, so as entirely to defend it from the mercury afterwards
to be used. When cold, the potash was solid, but containing
moisture enough to give it a conducting power; he then filled the
rest of the tube with mercury, and inverted it over the trough:
the apparatus being thus arranged, eurêka he made the wire and the
mercury alternately positive and negative. And now, conceiving
that I have sufficiently explained his brief notes, the reader
shall receive the result in his own words: for this purpose I have
obtained an engraving of the autograph, which is here annexed;
but as it may not be very readily deciphered, I shall first give
the substance of it in print.--"When potash was introduced into a
tube having a platina wire attached to it--so--and fused into the
tube so as to be a conductor, _i. e._ so as to contain just water
enough, though solid, and inserted over mercury, when the platina
was made negative, no gas was formed, and the mercury became
oxydated, and a small quantity of the _alkaligen_ was produced
round the platina wire, as was evident from its quick inflammation
by the action of water. When the mercury was made the negative,
gas was developed in great quantities from the positive wire,
and none from the negative mercury, and this gas proved to be
pure oxygene--A CAPITAL EXPERIMENT, PROVING THE DECOMPOSITION OF
POTASH." The Reviewer of the Institution Journal well observes that
those who knew Davy will best conceive the enthusiasm with which
this hasty record of his success was dashed off, and will instantly
recognise [Greek: eurêka] in his "CAPITAL EXPERIMENT."

From this same Register, it appears that, in the preceding month,
he was deeply engaged in experiments on '_Antwerp blue_,' which he
found to consist of _Prussiate of Iron_ and _Alumina_, "probably
in the proportion of two-thirds of the former to one-third of the
latter."

On the 6th of October, we learn from the same source, that he
performed a beautiful experiment, that of producing the vegetation
of the carbon of the wick of a candle, by placing it between the
wires of the battery.

On the 12th of the preceding September he addressed a letter to
Mr. Gilbert, which is curious, as it shows that very nearly up to
the time of the decomposition of the alkalies, his mind had been
engaged on very different subjects.


    TO DAVIES GIDDY, ESQ.

    September 12, 1807.

    MY DEAR SIR,

    I inclose Mr. Carne's paper, which, when you have read, and Mr.
    Carne revised, I will thank you to inclose to me, and that as soon
    as possible, for the completion of the volume.

    I have been a good deal engaged, since my return, in experiments on
    distillation, and I have succeeded in effecting what is considered
    of great importance in colonial commerce, namely, the depriving rum
    of its empyreumatic part, and converting it into pure spirit.

    I mention this in confidence, as it is likely to be connected with
    some profitable results; and it may be beneficial in a public point
    of view, by lessening the consumption of malt.

    I have heard of no scientific news; this, indeed, is little the
    season for active exertion.

    With best respects to your father, and to Mr. and Mrs. Guillemard,
    I am, my dear Sir,

    Always very faithfully yours,

    H. DAVY.


Few notes have conveyed information of such importance to the
scientific world, as that which follows, announcing, at the same
time, the decomposition of the fixed alkalies, and the formation of
the Geological Society, of which it would thus appear that Davy was
one of the founders.


    TO WILLIAM HASLEDINE PEPYS, ESQ.

    November 13, 1807.

    DEAR PEPYS,

    If you and Allen had been one person, the Council of the Royal
    Society would have voted to you the Copleian Medal;[77] but it is
    an indivisible thing, and cannot be given to two.

    We are forming a little talking Geological Dinner Club, of which I
    hope you will be a member. I shall propose you to-day. Some things
    have happened in the Chemical Club, which I think render it a less
    desirable meeting than usual, and I do not think you would find any
    gratification in being a member of it. Hatchett never comes, and we
    sometimes meet only two or three. I hope to see you soon.

    I have decomposed and recomposed the fixed alkalies, and discovered
    their bases to be two new inflammable substances very like metals;
    but one of them lighter than ether, and infinitely combustible. So
    that there are two bodies decomposed, and two new elementary bodies
    found.

    Most sincerely yours,

    H. DAVY.

  [77] He alludes to a Paper, entitled "On the Quantity of
  Carbon in Carbonic Acid, and on the Nature of the Diamond; by
  William Allen, Esq. F.R.S. and William Hasledine Pepys, Esq."
  Communicated by Humphry Davy, Sec. R.S. M.R.I.A. Read June 16,
  1807.


In the year 1808, MM. Gay Lussac and Thénard succeeded in
decomposing potash by chemical means; for which purpose it is
only necessary to heat iron turnings to whiteness in a curved
gun-barrel, and then to bring melted potash slowly in contact
with the turnings, air being excluded; when the iron, at that
high temperature, will take the oxygen from the alkali, and the
potassium may be collected in a cool part of the tube. It may
likewise be produced by igniting potash with charcoal, as M.
Curaudau showed in the same year.

In the following letter, Davy gives an account of his repeating
the experiment of MM. Gay Lussac and Thénard; mixing together, as
usual, science and angling.


    TO J. G. CHILDREN, ESQ.

    London, July 1808.

    MY DEAR SIR,

    I have this moment received your kind letter, and I have written
    to Pepys to propose to him to be with you on Sunday or Monday. I
    hope for his answer to-morrow morning, and I will write to you
    immediately.

    I will procure all the fishing tackle you have proposed, and am
    most happy to find you in so determined a spirit for piscatory
    adventure.

    I have had some letters from France; but nothing new, except an
    account of the gun-barrel experiment tolerably minute. I have
    tried it since, and procured potassium, but it was lost from
    some moisture passing into the aperture of the barrel. All that
    is necessary for the process is a gun-barrel bent thus, thus,
    B\______/\_/A.---- B represents the part where the touch-hole is
    closed; here dry potash is introduced; and the middle, which is to
    be strongly ignited, contains the filings; the potash is gradually
    fused and made to run down upon the ignited iron; the potassium
    collects in A.

    If you should be able to procure the apparatus for this experiment,
    I should like to assist in repeating it; and could we procure a
    large quantity of the basis, we may try its effects, on a great
    scale, on the undecompounded acids. I will bring some _dry boracic
    acid_. A copper or platina tube, if you have one, will be proper
    for trying the experiment in. We may likewise try its action upon
    the earths, and upon diamond.

    I have metallized Ammonia,[78] without the application of
    Electricity. When an amalgam of potassium and mercury is brought
    in contact with an ammoniacal salt, the potassium seizes upon the
    oxygen, and the hydrogen and nitrogen unite to the quicksilver.

    I had an opportunity of giving an account, on Friday, to the
    scientific men assembled at Greenwich, of your magnificent
    experiments and apparatus.[79] Sir Joseph Banks, Mr. Cavendish,
    Wollaston, &c. all expressed a strong wish that the results should
    be published. I am most happy you have drawn up the account.

    I regard the days I have passed in your society, as some of the
    pleasantest of my life. I look forward with a warm hope to our next
    meeting. Be pleased to assure your father of my highest respect,
    and of my gratitude for his kindness.

    I am, my dear Sir,

    Very sincerely yours,

    H. DAVY.

  [78] He here alludes to a train of research, which will be
  considered hereafter.

  [79] This observation relates to the magnificent battery
  constructed by Mr. Children, of which he presented an account to
  the Royal Society, in a Paper read in November 1808, entitled,
  "An Account of some Experiments, performed with a view to
  ascertain the most advantageous Method of constructing a Voltaic
  Apparatus, for the purpose of Chemical Research. By John George
  Children, Esq. F.R.S." The great battery described in this Paper
  consisted of twenty pairs of plates, each plate being four feet
  high by two feet wide: the sum of all the surfaces was ninety-two
  thousand one hundred and sixty square inches, and the quantity of
  liquid necessary for charging it, one hundred and twenty gallons.
  At the same time he constructed another battery, which consisted
  of two hundred pairs of plates, each being only two inches
  square. In the one case, then, he commanded extent of surface,
  in the other, extent of number; and by a series of comparative
  experiments, he fully established the theory of Davy (page 246),
  that the _intensity_ of Electricity increases with the _number_,
  and the _quantity_ with the _surface_.


It is impossible to reflect upon the chemical processes by which
potassium may be obtained, without feeling surprised that the
discovery should not have long before been accomplished. It is
evident that the substance must have been repeatedly developed
during the operations of chemistry; alkalies had been frequently
heated to whiteness in contact both with iron and charcoal, and in
some instances the appearance of a highly combustible body, which
could have been no other than potassium, had even been observed
as a result of the process, and yet no suspicion, as to its real
nature, ever crossed the mind of the experimentalist; he satisfied
himself with designating such a product, whenever it occurred, by
the term _Pyrophorus_.[80] I remember the late Mr. William Gregor
informing me that, in the course of his analytical experiments
with potash and different metals, he had repeatedly observed a
combustion on removing the crucible from the furnace, and exposing
its contents, which he could never understand. How admirably do
such anecdotes illustrate the remark made in the commencement of
the present chapter, that truth may be often touched, but is rarely
caught, in the dark!

  [80] The Pyrophorus of Homberg, of which a description is to
  be found in the _Mémoires de l'Academie_, for 1711, was made
  by mixing together any combustible body, as gum, flour, sugar,
  charcoal, &c. and alum, and then, after roasting the mixture till
  it was reduced to a dry powder, exposing it in a matrass to a red
  heat. In this process, the theory of which was first explained by
  Davy, the potash of the alum is converted into potassium, which,
  by its absorption of oxygen from the atmosphere, generates heat,
  and sets fire to the charcoal contained in the powder.

The facility of the combustion of the bases of the alkalies, and
the readiness with which they decomposed water, offered Davy the
ready means for determining the proportions of their constituent
parts: and in comparing all his results, he thinks that it will be
a good approximation to the truth, to consider potash as composed
of about six parts base and one of oxygen; and soda, as consisting
of seven base and two of oxygen.

The discovery of potassium led to that of the true nature of what
had been long familiar to chemists by the name of _pure Potash_,
but which ought to have been called the _hydrat_, for the _pure_
alkali was not known until after the discovery of Davy. The
experiments of MM. Gay Lussac and Thénard have shown this substance
to be a _Protoxide_. It is difficult of fusion; it has a grey
colour and a vitreous fracture, and dissolves in water with much
heat. The _Peroxide_ is procured by the combustion of potassium at
a low temperature; it had been observed by Davy in October 1807,
but at that time he supposed it to be the oxide containing the
smallest proportion of oxygen: it has a yellow colour, and when
thrown into water effervesces, and gives out oxygen gas.[81] When
heated very strongly upon platina, oxygen is also expelled from it,
and there remains the _protoxide_, or pure potash.

  [81] The 'Potassa Fusa' of our Pharmacopoeia generally contains a
  small proportion of the peroxide, and will therefore effervesce
  when thrown into water.

It was a great object with Davy, to show that the product resulting
from the combustion of potassium, was a pure oxide free from
water; for it is evident that had potassium been a _Hydruret_, its
combustion must have produced a _Hydrat_. This he accomplished by a
series of experiments which he performed in the laboratory of Mr.
Children, and which are published in his Bakerian Lecture of 1800.

Having discovered the presence of oxygen in the fixed alkalies, he
was naturally led by analogy to enquire whether ammonia might not
also contain it. It was true that the chemical composition of that
body had been considered as satisfactorily settled, and that the
conversion of it into hydrogen and nitrogen, in the experiments of
Scheele, Priestley, and Berthollet, had left nothing farther to be
accomplished. All new facts, however, are necessarily accompanied
by a new train of analogies; and Davy, in perusing the accounts of
the various experiments to which ammonia had been submitted, tells
us that he saw no reason for considering the presence of oxygen
as impossible; for, supposing hydrogen and nitrogen to exist in
combination with oxygen in low proportion, this latter principle
might easily disappear in the analytical experiments by heat and
electricity, in the form of water deposited upon the vessels
employed, or dissolved in the gases produced.

Under this impression, he commenced a series of experiments by
which, he says, he soon became satisfied of the existence of oxygen
in the volatile alkali. By means of the Voltaic battery, he ignited
perfectly dry charcoal in a small quantity of pure ammoniacal
gas, and he produced carbonate of ammonia; which could not have
happened, had not oxygen been furnished by the volatile alkali
to the carbon. In the next place, by an ingenious arrangement of
apparatus, he submitted ammonia to a high temperature, and effected
its decomposition, when a quantity of water appeared as one of the
products. It will be useless to enter into farther details upon
this occasion, as we shall presently perceive the subject assumed
a different aspect, and led the experimentalist into a new line of
enquiry.

At the conclusion of his Bakerian Lecture of 1807, he speaks of the
probable composition of the earths, and considers it reasonable to
expect that they are compounds of a similar nature to the fixed
alkalies--"peculiar highly combustible metallic bases united to
oxygen;"--but, as yet, this theory was sanctioned only by strong
analogies; it was his good fortune, at a subsequent period, to
support it by conclusive facts.

When the importance and novelty of the results he obtained from the
fixed alkalies, and their influence upon the reigning theories,
are duly considered, it may be easily imagined how intense was
the curiosity to witness the production of the new metals, to
examine their singular qualities, and to question the illustrious
discoverer upon their nature and relations. Suppose it were
publicly announced that one of the greatest Astronomers of the
day had invented a telescope of new and extraordinary powers;
and that by its means a hitherto unsuspected system of heavenly
bodies might be seen, the character and motions of which were
wholly inconsistent with the Newtonian theory of the universe.
The surprise and eager curiosity which such an announcement would
create might possibly be more general, because a knowledge of
Astronomy is more widely diffused than that of Chemistry; but the
sensation would not be more intense than that which the discovery
of potassium produced. The laboratory of the Institution was
crowded with persons of every rank and description; and Davy,
as may be readily supposed, was kept in a continued state of
excitement throughout the day. This circumstance, co-operating with
the effects of the fatigue he had previously undergone, produced a
most severe fit of illness, which for a time caused an awful pause
in his researches, broke the thread of his pursuits, and turned his
reflections into different channels.

He always laboured under the impression that the fever had been
occasioned by contagion, to which he had been exposed in one of
the jails during an experiment for fumigating it. This impression
appears to have continued through life, for in his "Last Days" he
alludes to it in terms of strong conviction.

Other persons referred his illness to the deleterious fumes,
especially those of Baryta, to which his experiments had exposed
him: an opinion recorded in an Epigram,[82] which was circulated
amongst the members of the Institution after his recovery.


    Says Davy to Baryt, "I've a strong inclination
    To try to effect your deoxidation;"
    But Baryt replies--"Have a care of your mirth,
    Lest I should retaliate, and change _you_ to Earth."


  [82] I received the above _jeu d'esprit_ from the late learned
  Orientalist, Mr. Stephen Weston, only four days before his death.
  Since its publication in the first edition of this work, a
  chemical friend sent me the following improved version of it.

    Says Davy to Baryt, "I feel strong temptation
    To effect by my art your deoxidation;
    And the money I've got in my pocket I'll bet all,
    I prove you a true, though disguised lad of metal."
    Says Baryt to Davy, "A truce to your mirth;
    If you turn me to metal, I'll turn you to earth;
    So moisten your clay, don't improve Science daily,
    Nor treat me as you've treated poor Soda and Kali."

Upon conversing, however, with Dr. Babington, who, with Dr.
Frank, attended Davy throughout this illness, he assured me
that there was not the slightest ground for either of these
opinions; that the fever was evidently the effect of fatigue and
an over-excited brain. The reader will not feel much hesitation
in believing this statement, when he is made acquainted with the
habits of Davy at this period. His intellectual exertions were of
the most injurious kind, and yet, unlike the philosophers of old,
he sought not to fortify himself by habits of temperance. Should
any of my readers propose to me the same question respecting
Davy, as Fontenelle tells us was put to an Englishman in Paris,
by a scientific Marquis, with regard to Newton,--whether he ate,
drank, and slept like other people?--I certainly should be bound
to answer in the negative.

Such was his great celebrity at this period of his career, that
persons of the highest rank contended for the honour of his
company at dinner, and he did not possess sufficient resolution
to resist the gratification thus afforded, although it generally
happened that his pursuits in the laboratory were not suspended
until the appointed dinner-hour had passed. On his return in the
evening, he resumed his chemical labours, and commonly continued
them till three or four o'clock in the morning; and yet the
servants of the establishment not unfrequently found that he
had risen before them. The greatest of all his wants was Time,
and the expedients by which he economised it often placed him
in very ridiculous positions, and gave rise to habits of the
most eccentric description: driven to an extremity, he would in
his haste put on fresh linen, without removing that which was
underneath; and, singular as the fact may appear, he has been
known, after the fashion of the grave-digger in Hamlet, to wear
no less than five shirts, and as many pair of stockings, at the
same time. Exclamations of surprise very frequently escaped
from his friends at the rapid manner in which he increased and
declined in corpulence.

At the commencement of his severe illness in November 1807, he
was immediately attended by Dr. Babington and Dr. Frank; and
upon its assuming a more serious aspect, these gentlemen were
assisted by Dr. Baillie. Such was the alarming state of the
patient, that for many weeks his physicians regularly visited him
four times in the day, and issued bulletins for the information
of the numerous enquirers who anxiously crowded the hall of the
Institution. His kind and amiable qualities had secured the
attachment of all the officers and servants of the establishment,
and they eagerly anticipated every want his situation might
require. The housekeeper, Mrs. Greenwood, watched over him with
all the care and solicitude of a parent; and, with the exception
of a single night, never retired to her bed for the period of
eleven weeks. In the latter stage of his illness, he was reduced
to the extreme of weakness, and his mind participated in the
debility of the body. It may not perhaps be thought philosophical
to deduce any inference, as to character, from traits which
are displayed under such circumstances: I have little doubt,
however, but that the mind, like inorganic matter, will, in its
decay, frequently develope important elements, which under other
conditions were not distinguishable. Suppose pride and timidity
to exist as qualities in the same mind, the former might so far
predominate as to enable its possessor to face the cannon's
mouth; but diminish its force by moral or physical agency, the
natural timidity will gain the ascendency, and the hero be
converted into a coward. Such are my reasons for introducing
the following anecdote: I would not give to it a greater value
than it deserves, but it surely demonstrates the existence of
kindly affections. Youthful reminiscences, and circumstances
connected with his family and friends, were the only objects
which, at this period, occupied his thoughts, and afforded him
any pleasure. No Swiss peasant ever sighed more deeply for his
native mountains, than did Davy for the scenes of his early
years. He entreated his nurse to convey to his friends his ardent
wish to obtain some apples from a particular tree which he had
planted when a boy; and, unlike Locke with his cherries, he had
no power of controlling the desire by his reason, but remained
in a state of restlessness and impatience until their arrival:
at the same time, he expressed a wish to obtain several other
objects, especially an ancient tea-pot, endeared to him by early
associations.

The following Minute appears on the Journals of the Institution:--

"December 7, 1807.--Mr. Davy having been confined to his bed for
the last fortnight by a severe illness, the Managers are under
the painful necessity of giving notice, that the Lectures will
not commence until the first week in January next."

The Course was, at the time stated, opened by the Reverend Mr.
(now Dr.) Dibdin; and his introductory lecture was, by order of
the Managers, printed "for the satisfaction of those proprietors
who were not present." It thus commences:--"Before I solicit your
attention to the opening of those Lectures which I shall have
the honour of delivering in the course of the season, permit me
to trespass upon it for a few minutes, by stating the peculiar
circumstances under which this Institution is again opened; and
how it comes to pass that it has fallen to me, rather than to a
more deserving lecturer, to be the first to address you.

"The Managers have requested me to impart to you that
intelligence, which no one who is alive to the best feelings
of human nature can hear without mixed emotions of sorrow and
delight.

"Mr. Davy, whose frequent and powerful addresses from this place,
supported by his ingenious experiments, have been so long and so
well known to you, has for these last five weeks been struggling
between life and death;--the effects of those experiments
recently made in illustration of his splendid discoveries, added
to consequent bodily weakness, brought on a fever so violent
as to threaten the extinction of life. Over him, it might
emphatically be said, in the language of our immortal Milton, that

               ----'Death his dart
    Shook, but delayed to strike.'

Had it pleased Providence to have deprived the world of
any further benefit from his original talents and immense
application, there certainly has been already enough effected
by him to entitle his name to a place amongst the brightest
scientific luminaries of his country. That this may not appear an
unfounded eulogium, I shall proceed, at the particular request of
the Managers, to give you an outline of the splendid discoveries
to which I have just alluded; and I do so with the greater
pleasure, as that outline has been drawn in a very masterly
manner by a gentleman of all others perhaps the best qualified to
do it effectually."

The Lecturer then proceeded to take a general and rapid view of
his labours, which it is unnecessary to introduce in this place,
and concluded as follows:--

"This recital will be sufficient to convince those who have heard
it of the celebrity which the author of such discoveries has a
right to attach to himself; and yet no one, I am confident, has
less inclination to challenge it. To us, and to every enlightened
Englishman, it will be a matter of just congratulation, that
the country which has produced the two BACONS and BOYLE, has in
these latter days shown itself worthy of its former renown by the
labours of CAVENDISH and DAVY. The illness of the latter, severe
as it has been, is now abating, and we may reasonably hope that
the period of convalescence is not very remote."

Fortunately for the cause of Science--fortunately for the
interests of the Institution, the prediction of the learned
Lecturer was shortly verified.

The Institution, indeed, had already suffered from the calamity;
for, in a Report to the Visitors, dated January 25, 1808, it is
stated, that "there has been an excess of expenditure beyond
the receipts. Among the causes of diminished income may be
mentioned the postponement of the lectures, in consequence of
the lamented illness of the excellent Professor of Chemistry;
and among the items of increased expenditure, the extra expense
of the Laboratory, in which have been produced Mr. Davy's recent
discoveries, so honourable to the Royal Institution, and so
beneficial to the interests of science in every part of the
world."

This Report is succeeded by the following Minute:--

"February 22, 1808.--Mr. Davy attended at the request of the
Committee, and informed them that he should be able to commence
his course of Lectures on Electro-chemical science on Saturday
the 12th of March, at two o'clock; and those on Geology on
Wednesday evening, the 16th of that month."

The following letter to Mr. Poole announces the restoration
of his health, and communicates some other circumstances of
interest. Mr. Poole, it would appear, entertained doubts as to
whether Davy received the prize of France for his first or second
Bakerian Lecture, upon which point this letter sets him right.


    TO THOMAS POOLE, ESQ.

    March, 1808.

    MY DEAR POOLE,

    Many thanks for your kind letter. I have seen your friend Mr.
    B---- for a minute, and, to use a geological term, I like his
    _aspect_, and shall endeavour to cultivate his acquaintance.

    I am exceedingly busy; my health is re-established; and I am
    entering again into the career of experiment.

    The prize which you congratulate me upon was given for my paper
    of 1806, and not for my last discoveries, which will probably
    excite more interest.

    C----, after disappointing his audience twice from illness, is
    announced to lecture again this week. He has suffered greatly
    from excessive sensibility--the disease of genius. His mind is as
    a wilderness, in which the cedar and the oak, which might aspire
    to the skies, are stunted in their growth by underwood, thorns,
    briars, and parasitical plants. With the most exalted genius,
    enlarged views, sensitive heart, and enlightened mind, he will
    be the victim of want of order, precision, and regularity. I
    cannot think of him without experiencing the mingled feelings of
    admiration, regard, and pity.

    Why do you not come to London? Many would be happy to see you;
    but no one more so than your very sincere friend, my dear Poole,

    H. DAVY.


It is difficult to convey an adequate idea of the universal
interest which was excited by the lectures on Electro-chemical
Science, to which an allusion has been just made. The Theatre of
the Institution overflowed; and each succeeding lecture increased
the number of candidates for admission.

It is unnecessary, after what has been already stated, to
describe the masterly style in which he demonstrated and
explained those general laws which his genius had developed, or
to enumerate the beautiful and diversified experiments by which
he illustrated their application, in simplifying the more complex
forms of matter.

His evening lectures on Geology were equally attractive; and by a
method as novel as it was beautiful, he exhibited, by the aid of
transparencies, the structure of mountains, the stratification of
rocks, and the arrangements of mineral veins.

The Easter recess afforded him a few days of leisure, which from
the following note he appears to have devoted to his favourite
amusement.


    TO W. H. PEPYS, ESQ.

    April, 1808.

    MY DEAR PEPYS,

    Children has had the kindness to arrange our party, and we are
    to meet him, at all events, on Tuesday at two o'clock, at Foot's
    Cray.

    I have proposed that we should leave town at about five or six
    on Monday evening, sleep at Foot's Cray, and try the fly-fishing
    there.

    Will you arrange with Allen, whom we must initiate in the
    vocation of the Apostles, as he wants nothing else to make him
    perfect as a primitive Christian and a Philosopher?

    I am, my dear Pepys,

    Most affectionately yours,

    H. DAVY.


Hitherto his passion for angling has only been noticed in
connection with his conversation and letters; I shall now present
to the reader a sketch of the philosopher in his fishing costume.
His whole suit consisted of green cloth; the coat having sundry
pockets for holding the necessary tackle: his boots were made of
caoutchouc, and, for the convenience of wading through the water,
reached above the knees. His hat, originally intended for a
coal-heaver, had been purchased from the manufacturer in its raw
state, and dyed green by some pigment of his own composition; it
was, moreover, studded with every variety of artificial fly which
he could require for his diversion. Thus equipped, he thought,
from the colour of his dress, that he was more likely to elude
the observation of the fish. He looked not like an inhabitant
o' the earth, and yet was on't;--nor can I find any object in
the regions of invention with which I could justly compare him,
except perhaps with one of those grotesque personages who, in the
farce of "The Critic," attend Father Thames on the stage, as his
two banks.

I shall take this opportunity of stating, that his shooting
attire was equally whimsical: if, as an angler, he adopted a
dress for concealing his person, as a sportsman in woods and
plantations, it was his object to devise means for exposing it;
for he always entertained a singular dread lest he might be
accidentally shot upon these occasions. When upon a visit to
Mr. Dillwyn of Swansea, he accompanied his friend on a shooting
excursion, in a broad-brimmed hat, the whole of which, with the
exception of the brim, was covered with scarlet cloth.

Notwithstanding, however, the refinements which he displayed in
his dress, and the scrupulous attention with which he observed
all the minute details of the art; if the truth must be told, he
was not more successful than his brother anglers; and here again
the temperament of Wollaston presented a characteristic contrast
to that of Davy. The former evinced the same patience and
reserve--the same cautious observation and unwearied vigilance
in this pursuit, as so eminently distinguished his chemical
labours. The temperament of the latter was far too mercurial:
the fish never seized the fly with sufficient avidity to fulfill
his expectations, or to support that degree of excitement which
was essential to his happiness, and he became either listless or
angry, and consequently careless and unsuccessful.--But it is
time to resume the thread of our chemical history.

It has been already stated, that Davy had no sooner decomposed
the fixed alkalies than he proceeded to effect an analysis of
the earths; but his results were indistinct: they could not,
like the alkalies, be rendered conductors of electricity by
fusion, nor could they be acted upon in solution, in consequence
of the strong affinity possessed by their bases for oxygen. The
pursuit of the enquiry then demanded more refined and complicated
processes, than those which had succeeded with potash and soda.

The only methods which held out any fair prospect of success
were those of operating by electricity upon the earths in some
of their combinations, or of converting them, at the moment
of their decomposition, into metallic alloys, so as to obtain
presumptive evidence of their nature and properties. Such, in
fact, was the line of enquiry in which Davy was deeply engaged,
when he received from Professor Berzelius of Stockholm a letter,
announcing the fact that he had, in conjunction with Dr.
Pontin, succeeded in decomposing baryta and lime, by negatively
electrising mercury in contact with them, and that, by such
means, he had actually obtained amalgams of the earths in
question.

Our philosopher immediately repeated the experiments, and with
perfect success. After which he completed a series of additional
experiments, which fully established the nature of these bodies,
and the analogies he had anticipated. These results formed the
subject of a memoir, which was read before the Royal Society on
the 30th of June 1808, and entitled, "Electro-chemical Researches
on the Decomposition of the Earths: with Observations on the
Metals obtained from them, and on the Amalgam of Ammonia."

He commences this paper by enumerating the several trials he
had made to effect the decomposition of these bodies; such as,
First, by electrifying them by iron wires under the surface of
naphtha, with a view to form alloys with iron and the metallic
bases of the earths. Secondly, by heating potassium in contact
with the alkaline earths, in the hope that this body might detach
the oxygen from them, in the same manner as charcoal decomposes
the common metallic oxides. Thirdly, by submitting various
mixtures of the earths and potash to Voltaic action, with the
idea that the potash and the earths might be deoxidated at the
same time, and entering into combination, form alloys. Fourthly,
by mixing together various earths with the oxides of tin, iron,
lead, silver, and mercury: a mode of manipulation suggested
by the results of his previous experiments on potassium, in
which he found that when a mixture of potash and the oxides of
mercury, tin, or lead, was electrified in the Voltaic circuit,
the decomposition was very rapid, and an amalgam, or an alloy of
potassium, was obtained; the attraction between the common metals
and the potassium apparently accelerating the separation of the
oxygen.

Supposing that a similar kind of action might assist the
decomposition of the alkaline earths, he proceeded to institute a
series of experiments upon that principle; and the results were
more satisfactory than those obtained by the preceding methods
of experimenting--a compound was obtained which acted upon water
with the evolution of hydrogen, producing a solution of the
earth, and leaving free the tin, or lead, with which its base may
be supposed to have been alloyed;--but in all such experiments
the quantity of the metallic basis produced must have been very
minute, and its character very questionable.

In this stage of the enquiry, Davy received the letter from
Professor Berzelius of Stockholm, the contents of which he
embodied in his memoir, accompanied with such observations as his
own information suggested.

"A globule of mercury, electrified by the power of a battery
consisting of five hundred pairs of double plates of six inches
square, weakly charged, was made to act upon a surface of
slightly moistened barytes, fixed upon a plate of platina. The
mercury gradually became less fluid, and after a few minutes was
found covered with a white film of barytes; and when the amalgam
was thrown into water, hydrogen was disengaged, the mercury
remained free, and a solution of barytes was formed.

"The result with lime, as these gentlemen had stated, was
precisely analogous.

"That the same happy methods must succeed with strontites and
magnesia, it was not easy to doubt, and I quickly tried the
experiment. From strontites I obtained a very rapid result; but
from magnesia, in the first trials, no amalgam could be procured.
By continuing the process, however, for a longer time, and
keeping the earth continually moist, at last a combination of the
bases with mercury was obtained, which slowly produced magnesia,
by absorption of oxygen from air, or by the action of water.

"All these amalgams I found might be preserved for a considerable
period under naphtha. In a length of time, however, they became
covered with a white crust under this fluid. When exposed to
air, a very few minutes only were required for the oxygenation
of the bases of the earths. In the water the amalgam of barytes
was most rapidly decomposed; that of strontites, and that of lime
next in order: but the amalgam from magnesia, as might have been
expected from the weak affinity of the earth for water, very
slowly changed: when, however, a little sulphuric acid was added
to the water, the evolution of hydrogen, and the production and
solution of magnesia, were exceedingly rapid, and the mercury
soon remained free."

In order, if possible, to procure the amalgams in quantities
sufficient for distillation, he combined the methods he had
employed in the first instance, with those pursued by Berzelius
and Pontin. "A mixture of the earth with red oxide of mercury was
placed on a plate of platina, a cavity was made in the upper part
of it to receive a globule of mercury, the whole was covered by a
film of naphtha, and the plate was made positive, and the mercury
negative, by a proper communication with the battery of five
hundred."

The amalgams thus procured were afterwards distilled in glass
tubes filled with the vapour of naphtha; by which operation
the mercury rose pure from the amalgam, and it was very easy
to separate a part of it; but the difficulty was to obtain a
complete decomposition, for to effect this, a high temperature
was required, and at a red heat the bases of the earths instantly
acted upon the glass, and became oxidated.

In the best result which Davy obtained in this manner, the
barytic basis appeared as a white metal of the colour of silver,
fixed at all common temperatures, but fluid at a heat below
redness, and volatile at a heat above it. Unlike the alkaline
bases, it would seem to be considerably heavier than water.

In extending these experiments to alumine, silex, zircone, &c.
after a most elaborate investigation, such results were not
obtained as justified the conclusion that they were, like the
other earths, metallic oxides; although, as far as they went,
they added to the probability of such analogy.

It will be remembered that, after the fixed alkalies had been
found to contain oxygen, Davy was very naturally led to enquire
whether ammonia might not also contain the same element, or be
an oxide with a binary base. In the communication from Professor
Berzelius, and Dr. Pontin, already alluded to, a most curious
experiment is related on what they consider the deoxidation
and amalgamation of the compound basis of ammonia; and which
they regard as supporting the idea which Davy had formed of
the presence of oxygen[83] in the volatile alkali. A fact so
startling as the production of a metallic body from ammonia, or
from its elements, immediately excited in Davy's mind the most
ardent desire to pursue the enquiry; and, after repeating the
original experiments of the Swedish chemists with his accustomed
sagacity, he modified his methods of manipulation, in order, if
possible, to obtain this metallic body in its most simple form;
but, although he succeeded in producing the amalgam without
Voltaic aid, by the intervention of potassium, he could not so
distill off the mercury as to leave the basis, or imaginary
_ammonium_, free.

  [83] See page 285.

The history of these researches into the nature of the ammoniacal
element concludes the lecture of which I have endeavoured to
give an outline. The subject of the amalgam is still involved in
mystery: if we suppose with Davy, that a substance, which forms
so perfect an amalgam with mercury, must of necessity be metallic
in its own nature, we cannot but conclude either that hydrogen
and nitrogen are both metals in the aëriform state, at the usual
temperatures of the atmosphere--bodies, for example, of the
same character as zinc and quicksilver would be at the heat of
ignition--or, that these gases are oxides in their common form,
but which become metallized by deoxidation--or, that they are
simple bodies, not metallic in their own nature, but capable of
composing a metal in their deoxygenated, and an alkali in their
oxygenated, state.

Before we venture, however, to entertain any opinions so
extravagant in their nature, and so wholly unsupported by analogy,
it would be well to enquire how far the change, which ammonia
and mercury undergo by Voltaic action, really merits the name of
amalgamation. Several chemists of the present day are inclined to
refer this change of form to a purely mechanical cause, by which
the particles of the metal become separated, and converted, as it
were, into a kind of _froth_ by the operation.[84]

  [84] The late interesting experiments of Mr. Daniell "on the
  action of Mercury on different Metals," which have been recently
  published in the first number of a new series of the Journal
  of the Royal Institution, appear to throw much light upon this
  subject. By agitating a few grains of spongy platinum with
  mercury in water acidified with acetic acid, he obtained an
  amalgam of the consistence of soft butter, which retained its
  consistence for many weeks, and greatly resembled that formed by
  the electrization of mercury in contact with ammonia. When the
  amalgam was laid upon filtering paper, the moisture was gradually
  absorbed and evaporated, and the mercury returned to a fluid
  state. By a more refined experiment, Mr. Daniell ascertained that
  the process was accompanied by the evolution of hydrogen gas;
  whence he very fairly concludes, that, when minutely divided,
  platinum is agitated with mercury, and moisture is present, an
  electrical action takes place, which, when heightened by the
  addition of a diluted acid, or the solution of a neutral salt, is
  sufficiently energetic to decompose water and evolve hydrogen:
  the oxygen at the same time combines with the mercury, and a
  solution is effected by the acetic acid, which its unassisted
  affinity could not have produced. "It also appears," continues
  Mr. Daniell, "that this electrical action communicates an
  adhesive attraction to the particles of the metal, by which
  the particles of liquid and aëriform bodies are entangled and
  retained, a kind of _frothy_ compound formed, and the fluidity
  of the mercury destroyed. The appearance of this amalgam is so
  very like that of the ammoniacal compound formed by exposing a
  solution of ammonia in contact with mercury to the influence of
  the Voltaic pile, or when an amalgam of potassium and mercury is
  placed upon moistened muriate of ammonia, that it is impossible
  not to be struck with the resemblance. Mr. Daniell is therefore
  inclined to believe that the production of the latter may be
  explained upon the same principles as that of the former.
  When the effect is produced by the direct application of the
  electrical current, by means of the battery, it ceases the moment
  the connexion between the poles is broken; and when brought about
  by the agency of the amalgam of potassium, the electrical action
  is doubtless excited by the contact of the two dissimilar metals,
  and the frothy compound lasts no longer than the existence of the
  potassium in the metallic state; whereas in the action between
  mercury and finely divided platinum, the permanence of the metals
  produces a much more lasting effect, and the soft amalgam may
  therefore be preserved for a greater length of time.

Mr. Brande, in a late communication in the Journal of the Royal
Institution,[85] observes: "Shortly after the discovery of a method
of obtaining Morphia in a pure state, I remember that Sir Humphry
Davy suggested the possibility of its affording, when electrised
in contact with mercury, results corresponding with those which
Berzelius had observed in respect to ammonia. He thought that
the nascent elements of the morphia, as liberated by electrical
decomposition, might, under such circumstances, effect a similar
apparent amalgam of the mercury, and he spoke of the subject as
likely to throw some light upon the corresponding ammoniacal
combinations. He made, I believe, a few experiments upon the
subject; but as the results were not such as he had anticipated,
they were not placed on record."

  [85] "On the Electro-chemical Decomposition of the
  Vegeto-Alkaline Salts." In this communication, the Professor
  gives an account of some experiments of his own, with a view
  to ascertain whether the vegetable alkalies, if electrised in
  contact with mercury, would impart any principle to the latter
  metal. In experiments with morphia and cinchonia, in which the
  mercury in contact with the vegetable base was rendered negative,
  not the least change in the fluidity of the metal could be
  perceived. When, however, a similar experiment was made with
  quina, the metal became filmy, and acquired even a tendency to a
  butyraceous appearance, but the phenomenon was found to depend
  upon the presence of a minute portion of lime.

In the progress of our ascent, it is refreshing to pause
occasionally, and to cast a glance at the horizon, which widens
at every increase of our elevation. By the decomposition of the
alkalies and earths, what an immense stride has been made in the
investigation of nature!--In sciences kindred to chemistry, the
knowledge of the composition of these bodies, and the analogies
arising from it, have opened new views, and led to the solution
of many problems. In Geology, for instance, has it not shown that
agents may have operated in the formation of rocks and earths,
which had not previously been known to exist? It is evident that
the metals of the earths cannot remain at the surface of our globe;
but it is probable that they may constitute a part of its interior;
and such an assumption would at once offer a plausible theory in
explanation of the phenomena of volcanoes, the formation of lavas,
and the excitement and effects of subterranean heat, and might even
lead to a general theory in Geology.

The reader, for the present, must be satisfied with these cursory
hints: I shall hereafter show that our illustrious philosopher
followed them up by numerous observations and original experiments
in a volcanic country.

I remember with delight the beautiful illustration of his theory,
as exhibited in an artificial volcano constructed in the theatre
of the Royal Institution.--A mountain had been modelled in clay,
and a quantity of the metallic bases introduced into its interior:
on water being poured upon it, the metals were soon thrown into
violent action--successive explosions followed--red-hot lava was
seen flowing down its sides, from a crater in miniature--mimic
lightnings played around: and in the instant of dramatic illusion,
the tumultuous applause and continued cheering of the audience
might almost have been regarded as the shouts of the alarmed
fugitives of Herculaneum or Pompeii.




CHAPTER VIII.

   Davy's Bakerian Lecture of 1808.--Results obtained from
   the mutual action of Potassium and Ammonia upon each
   other.--His belief that he had decomposed Nitrogen.--He
   discovers Telluretted Hydrogen.--Whether Sulphur, Phosphorus,
   and Carbon, may not contain Hydrogen.--He decomposes
   Boracic acid.--Boron.--His fallacies with regard to the
   composition of Muriatic acid.--A splendid Voltaic Battery
   is constructed at the Institution by subscription.--Davy
   ascertains the true nature of the Muriatic and Oxymuriatic
   Acids.--Important chemical analogies to which the discovery
   gave origin.--Euchlorine.--Chlorides.--He delivers Lectures
   before the Dublin Society.--He receives the Honorary Degree
   of LL.D. from the Provost and Fellows of Trinity College.--He
   undertakes to ventilate the House of Lords.--The Regent confers
   upon him the honour of Knighthood.--He delivers his farewell
   Lecture.--Engages in a Gunpowder manufactory.--His marriage.


The third Bakerian Lecture, which Davy read before the Royal
Society in December 1808, is entitled "An Account of some new
analytical Researches on the Nature of certain Bodies, particularly
the Alkalies, Phosphorus, Sulphur, Carbonaceous matter, and the
Acids hitherto undecompounded; with some general Observations on
Chemical Theory."

The object of this lecture was to communicate the results of
numerous experiments which had been instituted for the purpose of
still farther extending our knowledge of the elements of matter,
by the new powers and methods arising from the application of
electricity to chemical analysis.

Important as were the facts thus obtained, they disappointed
the expectation of those who did not consider, that the more
nearly we approach ultimate analysis,[86] the greater must be
the difficulties, the more numerous the fallacies, and the less
perfect the results, of our processes. In fact, his former
discoveries had spoilt us: their splendour had left our organs
of perception incapable of receiving just impressions from any
minor lights, and we participated with exaggerated feelings, in
the disappointment which he himself expressed at several of his
results. The confidence inspired by his former triumphs may be
compared to that which is felt by an army, when commanded by a
victorious General,--a conviction that, however difficult may be
the enterprise, it must be accomplished by the genius of him who
undertakes it. The moment we discovered that Davy was laying siege
to one of Nature's strongest holds,--that he was attempting to
resolve nitrogen into other elementary forms,--we regarded the
deed as already accomplished, and the repulse which followed most
unreasonably produced a feeling of dissatisfaction. Upon such
occasions, the severity of our disappointment will always be in
proportion to the importance of the object we desire to accomplish;
and it is impossible not to feel that the discovery of the true
nature of nitrogen would lead to new views in chemistry, the extent
of which it is not easy even to imagine.

  [86] The difficulty of seizing upon elementary forms, as well
  as the infinity of combinations of which they are susceptible,
  are supposed by Mr. Sankey to be allegorized in the fable of
  Proteus, [Greek: Prôteios], being derived from [Greek: prôtos],
  signifying the first element. It is not a little singular that
  Mr. Leslie, to whom such a speculation was wholly unknown, should
  have recognised in the same fable a picture of the cautious
  but intrepid advances of the skilful experimenter: he tries
  to press Nature into a corner,--he endeavours to separate the
  different principles of action,--he seeks to concentrate the
  predominant agent, and labours to exclude as much as possible
  every disturbing influence. Notwithstanding the confidence
  with which modern philosophers have claimed the discovery, the
  experimental mode of investigation was undoubtedly known and
  pursued by the ancients, who appear, observes Mr. Leslie, to have
  concealed their notions respecting it under the veil of allegory.
  _Proteus_ signified the mutable and changing forms of material
  objects; and the inquisitive philosopher was counselled by the
  Poets to watch their slippery demon, when slumbering on the shore
  to bind him, and to compel the reluctant captive to reveal his
  secrets.--_Elements of Natural Philosophy._

The principal objects of research which this paper embraces
are,--the elementary matter of ammonia; the nature of phosphorus,
sulphur, charcoal, and the diamond; and the constituents of the
boracic, fluoric, and muriatic acids. Enquiries which are continued
and extended in two successive papers, viz. in one read before the
Society in February 1809, entitled "New Analytical Researches on
the Nature of certain Bodies; being an Appendix to his Bakerian
Lecture of 1808;" and in his fourth Bakerian Lecture of 1809,
"On some new Electro-chemical Researches on various Objects,
particularly the Metallic bodies from the Alkalies and Earths; and
on some Combinations of Hydrogen."

With regard to these admirable papers,--for such they must
undoubtedly be considered,--the biographer must confine his
observations to their general character and results. They are far
too refined to admit of a brief analysis, and too elaborate to
allow a successful abridgement. A just idea of their merit can
alone be derived from a direct reference to the Philosophical
Transactions.

The enquiry commences with experiments on the results produced
by the mutual action of potassium and ammonia on each other. His
object was twofold: to refute the hypothesis which assumed hydrogen
as an element of potassium, and to ascertain the nature of the
matter existing in the amalgam of ammonia, or the supposed metallic
basis of the volatile alkali: a question intimately connected with
the whole of the arrangements of chemistry. As to the former point,
it is unnecessary to enter into farther discussion; and with regard
to the latter, it is quite impossible to convey an adequate idea of
the extent of the enquiry: there does not exist in the annals of
chemistry a more striking example of experimental industry.

In the course of his experiments on potassium and ammonia, he
obtained an olive-coloured body, which he was inclined to regard
as a compound of the metallic base of ammonia (_ammonium_) and
potassium; and on submitting which to various trials, he uniformly
obtained, as the product of its decomposition, a proportion of
nitrogen considerably less than that which, upon calculations
founded on a rigid analysis of the volatile alkali, ought to
have been afforded under such circumstances, while the potassium
employed at the same time became oxidated. This result inspired a
hope that nitrogen might have been actually decomposed during the
process, and that its elements were oxygen and a metallic basis, or
oxygen and hydrogen.

That he was sanguine in that hope, appears from the whole tenor
of his paper; in farther proof of which, I can adduce a letter
which he addressed to Mr. Children during the progress of his
experiments, in which he says, "I hope on Thursday to show you
nitrogen as a complete wreck, torn to pieces in different ways."
His subsequent enquiries, however, although they did not strengthen
the suspicion he had formed respecting the decomposition of that
body, yet indirectly developed facts of considerable importance;
which, with his characteristic quickness of perception, he made
subservient to fresh investigation.

His researches into the phenomena exhibited by tellurium, when
forming a part of the Voltaic circuit, are highly interesting. It
had been stated by Ritter, that, of all the metallic substances he
tried for producing potassium by negative electricity, tellurium
was the only one by which he could not procure it; and he uses this
fact in support of his opinion, that potassium is a _hydruret_.
He says, that when a circuit of electricity is completed in water
by means of two surfaces of tellurium, oxygen is given off at the
positive surface, and instead of hydrogen at the negative surface,
a brown powder is formed and separated, which he regards as a
_hydruret_ of tellurium; and he conceives that the reason why
that metal prevents the metallization of potash is, that it has a
stronger attraction for hydrogen than that possessed by the alkali.

Davy's attention was naturally arrested by such a statement,
and, in pursuing the enquiry, he discovered a series of new
facts:--he found that tellurium and hydrogen were capable of
combining, and of forming a gas, to which he gave the name of
_telluretted hydrogen_,--that, so far from tellurium preventing the
decomposition of potash, it formed an alloy with potassium when
negatively electrified upon the alkali--and, such was the intense
affinity of potassium and tellurium for each other, that the
decomposition of potash might be effected by acting on the oxide
of the latter metal and the alkali, at the same time, by heated
charcoal.

With respect to the next subject of enquiry in these papers,
_viz._ whether sulphur, phosphorus, and carbon, in their ordinary
forms, may not contain hydrogen, it would appear that from an
experiment performed by Mr. Clayfield, and which Davy witnessed
at Bristol in the year 1799, he was very early led to suspect the
existence of hydrogen in sulphur; but it was not until 1807, that
he entered upon the investigation of the subject. From the general
tenor of his experiments he concluded that, in its common state,
it may be regarded as a compound, of small quantities of oxygen
and hydrogen, with a large quantity of a basis which, on account
of its strong attractions for other bodies, has not hitherto been
obtained in its pure form. The same analogies apply to phosphorus
and carbon. His conclusion was mainly derived from the fact,
that hydrogen is produced from sulphur and phosphorus in such
quantities by Voltaic electricity, that he thinks it cannot well be
considered as an accidental ingredient in them: the presence of
oxygen, he contends, may be inferred from the circumstance that,
when potassium is made to act upon these bodies, the sulphurets
and phosphurets so formed evolve by the action of an acid less
hydrogen, in the form of compound inflammable gas, than the same
quantity of potassium in an uncombined state. The question,
however, still remains in considerable doubt; and in his "Elements
of Chemical Philosophy," published four years afterwards, he admits
that no accurate conclusions have been formed on the subject.

In his second Bakerian Lecture of 1807, Davy had given an account
of an experiment in which boracic acid appeared to be decomposed
by Voltaic electricity, a dark-coloured inflammable substance
separating from it on the negative surface. In the memoir now
under consideration, he procured the basis by heating together
boracic acid and potassium, when he ascertained it to be a peculiar
inflammable matter, which, after various experiments upon its
nature, he was inclined to regard as metallic; on which account he
proposed for it the name of _Boracium_. At about the same period,
MM. Gay Lussac and Thénard were engaged in investigating the same
subject in France, and they anticipated him in some of the results.

When Davy, by subsequent experiments, had ascertained that the base
of the boracic acid is more analogous to carbon than to any other
substance, he adopted the term _Boron_, as less exceptionable than
that of _Boracium_.

At this time, he also entered upon the investigation of
fluoric acid, the results of which must be reserved for future
consideration.

His experiments and reasonings upon muriatic acid, at this period
of his career, must be now considered as deriving their greatest
degree of interest from their fallacy; and they deserve an
examination in this work, if it be only to estimate the vigour
he subsequently displayed in disentangling himself from a web of
his own fabrication. The most satisfactory proof of intellectual
strength is to be found in the existence of a power which enables
the mind to conquer its prejudices and to correct its own errors.
How many remarkable instances does the history of science present,
in which the philosopher has treated his facts as Procrustes did
his victims, in order that they might accord with the measure most
convenient for his purpose!

Prejudiced by the general opinion respecting the hitherto
undecompounded nature of muriatic acid, he had long sought to
discover its radical by the agency of Voltaic electricity; but he
uniformly found that when its aqueous solution was thus acted upon,
the water alone underwent decomposition; while the electrization
of the gas afforded no other indication of its nature than the
presence of a much greater quantity of water than theory had
assigned to it. He proceeded, therefore, to examine the acid by
other modes of enquiry: he found, by the action of potassium upon
the gas, that a large volume of hydrogen was evolved, which,
in conjunction with other experiments, satisfied him that this
body, in its common aëriform state, contained at least one-third
of its weight of water; and he adopted various expedients with
the hopes of obtaining the acid free from it. Without pursuing
him through this research, I shall merely state the conclusions
at which he arrived, _viz._ that dry muriatic acid, could it be
obtained, would probably be found to possess the strongest and most
extensive powers of combination of all known substances belonging
to the class of acids; and that its basis, should it ever be
separated in a pure form, will be one of the most powerful agents
in Chemistry. From the fact of water appearing in a separate state,
and oxymuriatic acid being formed whenever a metallic oxide was
heated in muriatic acid gas, he was led to consider the muriatic
acid as a compound of a certain base, (not hitherto obtained in a
separate state,) and not less than one-third part of water; while
he regarded oxymuriatic acid as a compound of the same base (free
from water) with oxygen.

After the numerous experiments in which the original battery
of the Institution had been used, so greatly were its metallic
plates corroded, that it was found to be no longer serviceable;
in consequence of which, as it would appear from a minute, dated
July 11, 1808, "Mr. Davy laid before the Managers of the Royal
Institution the following paper, _viz._

"A new path of discovery having been opened in the agencies of
the electrical battery of Volta, which promises to lead to the
greatest improvements in Chemistry and Natural Philosophy, and the
useful arts connected with them; and since the increase of the
size of the apparatus is absolutely necessary for pursuing it to
its full extent, it is proposed to raise a fund by subscription,
for constructing a powerful battery, worthy of a national
establishment, and capable of promoting the great objects of
science.

"Already, in other countries, public and ample means have been
provided for pursuing these investigations. They have had their
origin in this country; and it would be dishonourable to a nation
so great, so powerful, and so rich, if, from the want of pecuniary
resources, they should be completed abroad.

"An appeal to enlightened individuals on this subject can scarcely
be made in vain. It is proposed that the instrument and apparatus
be erected in the Laboratory of the Royal Institution, where it
shall be employed in the advancement of this new department of
science."

The Minute goes on then to state that--

"The above paper having been laid before the Board of Managers,
they felt it their indispensable duty instantly to communicate
the same to every member of the Royal Institution, lest the
slightest delay might furnish an opportunity to other countries for
accomplishing this great work, which originated in the brilliant
discoveries recently made at the Royal Institution.

"The Managers present agree to subscribe to this undertaking.

"ORDERED, that a book be opened at the Steward's office for the
purpose of entering the names of all those members who may wish to
contribute towards this important National object."

To the great gratification of Davy, and to the honour of the
country, the list of subscribers was soon completed, and one of the
most magnificent batteries ever constructed was speedily in full
operation.

It is thus alluded to in his Elements of Chemical Philosophy:--"The
most powerful combination that exists, in which number of
alternations is combined with extent of surface, is that
constructed by the subscriptions of a few zealous cultivators and
patrons of science, in the Laboratory of the Royal Institution. It
consists of two hundred instruments connected together in regular
order, each composed of ten double plates arranged in cells of
porcelain, and containing in each plate thirty-two square inches;
so that the whole number of double plates is two thousand, and the
whole surface one hundred and twenty-eight thousand square inches."

This battery, when the cells were filled with sixty parts of water
mixed with one part of nitric acid, afforded a series of brilliant
and impressive effects. When pieces of charcoal, about an inch
long, and one-sixth of an inch in diameter, were brought near
each other, (within the thirtieth or fortieth parts of an inch,)
a bright spark was produced, and more than half the volume of the
charcoal became ignited to whiteness, and by withdrawing the points
from each other a constant discharge took place through the heated
air, in a space equal at least to four inches, producing a most
brilliant ascending arch of light, broad and conical in form in
the middle. When any substance was introduced into this arch, it
instantly became ignited; platina melted as readily in it as wax
in the flame of a common candle; quartz, the sapphire, magnesia,
lime, all entered into fusion; fragments of diamond, and points of
charcoal and plumbago rapidly disappeared, and seemed to evaporate
in it, even when the connexion was made in a receiver exhausted by
the air-pump; but there was no evidence of their having previously
undergone fusion.

All the phenomena of chemical decomposition were produced with
intense rapidity by this combination. When the points of charcoal
were brought near each other in non-conducting fluids, such as
oils, ether, and oxymuriatic compounds, brilliant sparks occurred,
and elastic matter was rapidly generated.

Among the numerous experiments performed by the aid of this
battery, he instituted several, in the hope of decomposing
nitrogen; and which are recorded in his Bakerian Lecture of 1809.
He ignited potassium, by intense Voltaic electricity, in this gas;
and the result was, that hydrogen appeared, and some nitrogen was
found deficient. This, on first view, led him to the suspicion that
he had attained his object; but, in subsequent experiments, in
proportion as the potassium was more free from a coating of potash,
which necessarily introduced water, so in proportion was less
hydrogen evolved, and less nitrogen found deficient. The general
tenor of these enquiries, therefore, did not strengthen the opinion
he had formed with respect to the compound nature of nitrogen.

It appears from the following letter, that Davy visited his friend
Mr. Andrew Knight at Downton, in September 1809. It is introduced
in these memoirs principally for the purpose of showing with what
boldness he was accustomed to depart from generally received
opinions, and to project new theories for the explanation of the
most abstruse subjects.


    TO JOHN GEORGE CHILDREN, ESQ.

    September 23, 1809.

    MY DEAR FRIEND,

    I am about to visit Downton, and shall return by the first of
    October. I have neither seen nor heard from Lord Darnley, and I
    conjecture he has not yet returned from Scotland.

    I wish you great sport in pheasant-shooting, but I trust you have
    had still nobler game in your Laboratory.

    I doubt not you have found before this, as I have done, that the
    substance we mistook for _sulphuretted_ hydrogen is _telluretted_
    hydrogen, very soluble in water, combinable with alkalies and
    earths, and a substance affording another proof that hydrogen is
    an oxide. I have met with another analogous compound, that of
    _boracium_ with hydrogen, which possesses very similar properties.

    I find that taking _ammonium_ as the basis of hydrogen, according
    to the ideas which I stated, all the compounds will agree with the
    suppositions that I mentioned to you, _viz._ eight cubic inches
    of hydrogen, two of oxygen, ammonia; four and two, water; four
    and four, nitrogen; four and six, nitrous oxide; four and eight,
    nitrous gas; four and ten, nitric acid. Where the multiples are not
    in geometrical order, the decomposition is most easy, _i.e._ in
    nitrous oxide and nitric acid; more easy in water than in ammonia;
    but most difficult in nitrogen, where there is probably the most
    perfect equilibrium of affinities.

    I have kept charcoal white hot by the Voltaic apparatus, in
    dry oxymuriatic acid gas for an hour, without effecting its
    decomposition. This agrees with what I had before observed with a
    red heat. It is as difficult to decompose as nitrogen, except when
    all its elements can be made to enter into new combinations.

    I find the radiation, _in vacuo_, from ignited platina, is to that
    in air as three to one:--so much for Leslie's hypothesis.

    A little electrical machine acts with a repulsion as two, in a
    vacuum equal to five inches of mercury; as thirty, in common air;
    as thirty, in oxygen; as twenty-nine or thirty, in hydrogen;
    and as forty-five, in carbonic acid. I showed this experiment,
    made with every precaution, to Mr. Cavendish, Dr. Herschell, Dr.
    Wollaston, and Warburton: so much for the theory, that electricity
    is dependent upon oxidation. I do not think our worthy friend Pepys
    will resist any longer.

    Pray let me know what you have been doing. I hope you will not
    suffer these beautiful and satisfactory experiments of the
    capacities of metals to remain still. Write me a letter as
    egotistical as the one I have given you. You are pledged to do good
    and noble things, and you must not disappoint the men of science of
    this country.

    With kindest remembrances to your excellent father, and with hopes
    that we shall soon meet, I am, my dear friend,

    Very faithfully and affectionately yours,

    H. DAVY.


The genius displayed by Mr. Knight in investigating the phenomena
of vegetable nature, and in applying the knowledge thus acquired
to objects of practical improvement, excited in Davy, as might
have been expected, feelings of the highest admiration; and when,
in addition to such claims, he was the acknowledged patron and
hospitable friend of the angler, the reader will readily imagine
the warmth of feeling with which our philosopher cherished his
friendship.

On commencing the present work, I applied to Mr. Knight for any
assistance he might be able to afford me, in aid of so arduous a
labour; and he very kindly returned an answer, from which I extract
the following passage.

"My late lamented friend, Sir Humphry Davy, usually paid me a
visit in the autumn, when he chiefly amused himself with angling
for grayling, a fish which he appeared to take great pleasure in
catching. He seemed to enjoy the repose and comparative solitude of
this place, where he met but few persons, except those of my own
family, for we usually saw but little company. He always assured me
that he passed his visits agreeably, and I had reason to believe he
expressed his real feelings.

"In the familiar conversations of these friendly visits, he always
appeared to me to be a much more extraordinary being than even his
writings, and vast discoveries, would have led me to suppose him;
and, in the extent of intellectual powers, I shall ever think that
he lived and died without an equal."

The reader has already been made acquainted with those experiments
which led Davy to modify the prevailing opinions, with regard to
the constitution of the muriatic and oxymuriatic acids; and on the
false assumption that oxygen existed in the latter gas, to refer
the deposition of water which takes place upon heating a metallic
oxide in the former, to the supposition that muriatic acid contains
a large proportion of water as essential to its composition.
Upon observing, however, that charcoal, if freed from hydrogen
and moisture, even when ignited to whiteness in oxymuriatic, or
muriatic acid gas, by the Voltaic battery, did not effect the least
change in them, he was led to suspect the accuracy of his previous
conclusion; and on retracing his steps, and entering upon a new
path of enquiry, he ultimately succeeded, after one of the most
acute controversies that ever sprang from a chemical question,
in recalling philosophers to the original theory of Scheele, by
establishing the important truth, that oxymuriatic acid is, in the
true logic of chemistry, a simple body, which becomes muriatic acid
by its union with hydrogen.

The new views arising out of such a revolution in chemical opinion
are certainly not the least important of those to which the
discoveries of Davy have given birth. Dr. Johnson has remarked,
that "one of the most hazardous attempts of criticism is to choose
the best amongst many good." I am much mistaken, however, if the
chemists of Europe will not, without hesitation, pronounce his
researches into the nature of oxymuriatic acid, and its relations,
with the exception of those by which he established the chemical
laws of Voltaic action, to be by far the most important of all his
labours; not only as evincing the ascendancy of his genius, and the
steadiness of his perseverance, but as marking a new and splendid
era in chemical science.

It is much more difficult to eradicate an ancient error than to
establish a new truth; and on this occasion, he had not only to
contend against the pampered errors of a domineering system, but
against the equivocal and illusive evidence, or, if I may be
allowed the expression, the apparent neutrality of facts by which
the truth of his theory was to be judged. In consequence of the
constant and often unsuspected interference of water, there is
scarcely a result connected with the chemical history of the bodies
in dispute, that did not admit of being equally well explained upon
the hypothesis that oxymuriatic acid is a compound, as upon that
of its being a simple or undecompounded substance. The question
could never have been determined but by an investigation of the
most refined and subtile nature; so delicately was the evidence
balanced, that nothing but the keenest eye, and the steadiest hand,
could have determined the side on which the beam preponderated.

The illustrious discoverer of oxymuriatic acid considered that body
as muriatic acid freed from hydrogen, or, in the obscure language
of the Stahlian school, as muriatic acid deprived of phlogiston,
whence he assigned to it the name of _dephlogisticated_ muriatic
acid. Upon the establishment of the antiphlogistic theory by
Lavoisier, it became essential to the generalization which
distinguished it, that a body performing the functions of an acid,
and above all, supporting the process of combustion, should be
regarded as containing oxygen in its composition; and facts were
not wanting to sanction such an inference. The substance could
not even be produced from muriatic acid, without the action of
some body known to contain oxygen; while the fact of such a body
becoming deoxidated by the process, seemed to demonstrate, beyond
the possibility of error, that the conversion of the muriatic into
the oxymuriatic acid, was nothing more than a simple transference
of oxygen from the oxide to the acid: an opinion which was
universally adopted, and which for nearly thirty years triumphed
without opposition.

The body of evidence by which Davy overthrew this doctrine, and
established the undecompounded nature of oxymuriatic acid, is to
be found in a succession of papers read before the Royal Society,
_viz._ in that already announced,--in his Bakerian Lecture for
1810,--and in a subsequent memoir read in February 1811.

It will be impossible for me to follow the author through all the
intricacies of the enquiry; but I shall seize upon some of its more
prominent points, and give a general outline of its bearings.

No sooner had his suspicions been excited with regard to the
compound nature of oxymuriatic acid, than it occurred to him that,
if oxygen were really present in that body, he might readily obtain
it from some of its compounds; that, for instance, its combination
with tin would yield an oxide of that metal by ammonia; while
those with phosphorus would furnish, on analysis, either the
phosphor_ous_, or phosphor_ic_ acid. But after experiments in which
the presence of water was most cautiously excluded, the results he
had anticipated were not obtained. In the place of an oxide of tin,
the product, on the application of heat, volatilized in dense and
pungent fumes; and, instead of obtaining an acid of phosphorus, a
body possessing new and unexpected properties resulted. Again,--it
had been stated, in confirmation of the theory that recognised the
presence of oxygen in oxymuriatic acid, that when this latter body
and ammonia were made to act upon each other, water was formed: our
chemist frequently repeated the experiment, and convinced himself
that such was not the fact.

It had been shown by Mr. Cruickshank, and more recently proved by
MM. Gay Lussac and Thénard, that oxymuriatic acid and hydrogen,
when mixed in nearly equal proportions, produce a matter almost
entirely condensable by water, which is common muriatic acid;
and that water is not deposited in the operation. Davy made many
experiments on the subject, and he found, that when these gases
were mingled together in equal volumes over water, introduced into
an exhausted vessel, and fired by the electric spark, muriatic acid
resulted, although, at the same time, there was a certain degree of
condensation, and a slight deposition of vapour; but on repeating
the experiment in a manner still more refined, and by carefully
drying the gases, such condensation became proportionally less.

When, in addition to the above experimental evidence, it is stated
that MM. Gay Lussac and Thénard had proved, by a copious collection
of instances, that in the usual cases where oxygen is eliminated
from oxymuriatic acid, water is always present, and muriatic acid
gas is formed; and as it has been moreover shown that oxymuriatic
is converted into muriatic acid gas by combining with hydrogen, it
is scarcely possible to avoid the conclusion, that the oxygen is
derived from the decomposition of water, and not from that of the
acid.

When mercury is made to act, by means of Voltaic electricity, upon
one volume of muriatic acid gas, all the acid disappears, calomel
is formed, and half a volume of hydrogen is evolved.

By such experiments and arguments, Davy was led to the conclusion
that, as yet, oxymuriatic acid has not been decompounded; that it
is a peculiar body, elementary as far as our knowledge extends, and
analogous, in its tendency of combination with inflammable matter,
to oxygen gas; that, in fact, it may be a _peculiar_ acidifying and
dissolving principle, forming with different substances compounds
analogous to acids containing oxygen, or to oxides, in their
properties and powers of combination, but differing from them in
being, for the most part, decomposable by water. On this idea, he
thinks that muriatic acid may be considered as having hydrogen for
its base, and oxymuriatic acid for its acidifying principle. In
confirmation of such an opinion, it is also important to remark,
that in its electrical relations, oxymuriatic acid maintains its
analogy to oxygen.

The vivid combustion of bodies in oxymuriatic acid gas, Davy
acknowledges, may, at first view, appear a reason why oxygen should
be admitted as one of its elements; but he answers this argument
by stating, that heat and light are merely results of the intense
agency of combination; and that sulphur and metals, alkaline earths
and acids, become alike ignited under such circumstances.

As change of theory with regard to the primitive must necessarily
modify all our views with respect to the nature of secondary
bodies, so must this new view of oxymuriatic acid affect all our
opinions respecting its compounds. Davy accordingly proceeded, in
the first place, to investigate the various bodies which had been
distinguished by the name of _hyper-oxymuriates_, _muriates_, &c.

It also became necessary to alter the nomenclature, since to call
a body which neither contains oxygen nor muriatic acid, by a term
which denotes the presence of both, is contrary to those very
principles which first suggested it. Having consulted some of the
most eminent philosophers, Davy proposed a name founded upon one of
the most obvious and characteristic properties of the oxymuriatic
acid, namely, its colour, and called it CHLORINE.

If then oxymuriatic acid, or chlorine, does not contain any oxygen,
a question immediately arises as to the true nature of those
compounds in which the muriatic acid has been supposed to exist in
combination with a much larger proportion of oxygen than in the
oxymuriatic acid,--in the state in which it has been named by Mr.
Chenevix _hyper-oxygenized_ muriatic acid.

In his Bakerian Lecture of 1810, entitled, "On some of the
Combinations of Oxymuriatic Gas and Oxygen, and on the Chemical
Relations of these Principles," he details a number of experiments
for the illustration of this subject, and arrives at the
conclusion, that the oxygen in the hyper-oxymuriate of potash is
in triple combination with the metal and chlorine. He likewise
confirms his views, with regard to the elementary nature of
this latter body, by a series of new enquiries, and shows that
they are not incompatible with known phenomena:--for instance,
Scheele explained the bleaching powers of oxymuriatic gas, by
supposing that it destroyed colours by combining with _Phlogiston_.
Berthollet[87] considered it as acting by imparting oxygen; Davy
now proves that the pure gas is wholly incapable of altering
vegetable colours, and that its operation in bleaching entirely
depends upon its property of decomposing water, and of thus
liberating its oxygen.[88] The experiment by which he demonstrated
this fact is so simple and satisfactory, that I shall here relate
it. Having filled a glass globe, containing dry powdered muriate of
lime, with oxymuriatic gas, he introduced into another globe, also
containing muriate of lime, some dry paper tinged with litmus,
that had been just heated; by which device the intrusion of
moisture was effectually prevented. After some time, this latter
globe was exhausted, and then connected with that containing the
oxymuriatic gas, and by an appropriate set of stop-cocks, the paper
was exposed to the action of the gas thus dried: no change of
colour in the test paper took place, and after two days, there was
scarcely a perceptible alteration; while some similar paper dried
and introduced into the gas, that had not been exposed to muriate
of lime, was instantly bleached.

  [87] Berthollet first applied oxymuriatic acid for the purpose
  of bleaching, in France; from whence Mr. Watt introduced it into
  England.

  [88] Dr. Thomson has more recently explained the operation,
  by supposing that water is decomposed, and that its hydrogen
  goes to the chlorine, and its oxygen to the water, forming with
  the latter a deutoxide of hydrogen, or the oxygenated water of
  Thénard, which he considers as the true bleaching principle.

As an illustration of the eagerness with which he seized upon
facts, in order to apply them to economical purposes, it may be
stated that, on reflecting upon the theory of bleaching, and on
the changes which its agents undergo, he was led to propose the
use of a liquor produced by the condensation of oxymuriatic gas in
water, containing magnesia diffused through it, as superior to the
oxymuriate of lime commonly employed.[89]

  [89] Experience has not confirmed the value of this suggestion.
  Davy imagined that the vegetable fibre was injured by the
  saline residuum; and having found that muriate of magnesia was
  less corrosive than muriate of lime, he was led to propose
  the substitute above stated. The fact, however, is, that the
  fibre is injured by the chlorine; and as this body has only a
  slight affinity for magnesia, it too quickly abandons it; and
  consequently the oxymuriate of lime is still preferred.

It has been very truly observed, that all knowledge which is gained
tends towards the acquisition of more, just as the iron dug from
the mine facilitates in return the working of the miner. Never
was this truth more forcibly illustrated than by the discovery of
the nature of chlorine. In the progress of that train of enquiry,
which became necessary for the adjustment of our views as they
regarded the combinations of that body, Davy discovered a series of
new compounds, the history of which he communicated in successive
papers to the Royal Society.

In a memoir read in February 1811, entitled, "On a Combination
of Oxymuriatic Gas and Oxygen Gas," he announced the existence
of a _protoxide_ of chlorine, under the name of _Euchlorine_;
and in a communication from Rome in the year 1815, he described
another compound of chlorine and oxygen, containing a still larger
proportion of this latter element, and which has since been made
the subject of a series of experiments by Count Stadion of Vienna.
As it does not exhibit any acid properties, Dr. Henry proposes
to call it a _Peroxide_, in preference to _Deutoxide_; thinking
it probable that intermediate compounds, between this and the
protoxide already mentioned, may be hereafter discovered.

His paper on _euchlorine_ abounds with interest. He found that
by acting on the salts formerly denominated _hyper-oxymuriates_,
by muriatic acid, the gas evolved differed very greatly in its
properties, with the different modes of preparing it. When
much acid was employed with a small quantity of the salt, and
the gas was collected over water, it was not found to differ
from oxymuriatic gas; but when, on the other hand, the gas was
procured by means of a weak acid, and a considerable excess of
the salt, at a low heat, and was collected over mercury, it
possessed properties essentially different. Its colour, under such
circumstances, was of a dense tint of brilliant yellow-green,
whence the name of _euchlorine_.[90] When in a pure form, this gas
is so readily decomposed, that it will sometimes explode during the
time of its transfer from one vessel to another, producing both
heat and light with an expansion of volume,[91] and it may always
be made to explode by a very gentle heat, often even by that of the
hand.

  [90] From [Greek: eu] and [Greek: chlôros].

  [91] The most vivid effects of combustion known are those
  produced by the _condensation_ of oxygen, or chlorine: but
  in this instance, a violent explosion with heat and light is
  produced by their separation, and _expansion_; a perfectly novel
  circumstance in chemical philosophy.

The results of its explosion indicate its composition to be one
atom of chlorine, and one of oxygen. None of the metals that burn
in chlorine act upon this gas at common temperatures; but when the
oxygen is separated, they then inflame in the residual chlorine.
This fact Davy illustrated by a series of experiments, one of
which, from its extreme beauty, I shall here relate. If a glass
vessel, containing copper-leaf, be exhausted, and the euchlorine
afterwards admitted, no action will take place; but throw in a
little nitrous gas, and a rapid decomposition will ensue, and the
metal will burn with its accustomed brilliancy.

The discovery of this interesting gas, and that of the facts
connected with it, not only confirmed the novel views with regard
to the elementary nature of chlorine, but they reconciled the
contradictory accounts of different authors respecting the
properties of that body.

The weak attraction subsisting between the elements of this
compound gas, which by a comparatively low temperature are made
repulsive of each other, confirms also the supposition of Davy,
that oxygen and chlorine belong to the same class of bodies.

The discovery of the _peroxide of chlorine_ was made during an
examination of the action of acids on the _hyper-oxymuriates_ of
Chenevix, undertaken by Davy in consequence of a statement of
M. Gay Lussac, that a peculiar acid, which he called _chloric
acid_, might be procured from the _hyper-oxymuriate of baryta_ by
sulphuric acid. With regard to this acid, which its discoverer
considered as composed of one atom of chlorine and five atoms of
oxygen, Davy entered into a warm controversy, affirming that the
fluid in question owed its acid powers to combined hydrogen; and
that it was analogous to the other hyper-oxymuriates, as being
triple compounds of inflammable bases with chlorine and oxygen, in
which the two former determine the character of the compound: this
opinion, however, he afterwards abandoned, and I have reason to
believe that he regretted ever having advanced it.

Amidst these new views, it became necessary to alter our opinions
with regard to many of those compounds which have been termed
_muriates_, but which, it would appear, contain neither muriatic
acid nor oxygen, but are, strictly speaking, combinations of metals
with chlorine, held in union by a very powerful affinity, since
chlorine is capable of expelling the whole of the oxygen from any
metallic oxide, and of taking its place; even those metals that
are most distinguished by their affinity for oxygen, abandon it
whenever their oxides are heated in chlorine, in which case oxygen
gas is disengaged.

The same metal is also capable of uniting with different
proportions of chlorine, which, so far as has been yet ascertained,
are definite, and in no case exceed two proportions to one of
metal. Hence it was proposed by Davy, in fixing the nomenclature of
these compounds, to designate such as contain the least proportion
of chlorine by the termination _ane_, added to the Latin name
of the metal, as _cuprane_ for that of copper; those containing
the larger proportion of chlorine, by the termination _anea_,
as _cupranea_. The chemical name of our common culinary salt,
in conformity with such a nomenclature, would be _sodane_. This
proposition, however, has not been adopted;[92] the compounds
of metals and chlorine are either called _chlorurets_, or what
is preferable, from their analogy with the similar compounds
of oxygen, _chlorides_, and which are further distinguished as
_protochlorides_, _deutochlorides_, &c.

  [92] A little reflection will convince us that such a
  nomenclature could never have been adopted with propriety. It
  is in direct defiance of the Linnæan precept, that a specific
  name must not be united to the generic as a termination; besides
  which, such terms could never have been preserved in translations
  into other languages.

In connexion with the history of these chlorides, a question
arises of great interest and obscurity, and which has engaged the
attention of some of our most distinguished chemists,--whether
such a body, when dissolved by water, remains as a chloride; or,
by decomposing that fluid, and combining with its elements, is
not immediately converted into a muriate? With respect to several
of these chlorides, no doubt can be entertained as to the fact of
their decomposing water; for instance, the chloride of phosphorus
is thus acted upon, the oxygen of the water forms phosphorous acid
with the phosphorus, while its hydrogen unites with the chlorine
to form muriatic acid; and as those products are such as do not
combine with each other, but exist in a state of mixture in the
water, each may be recognised by its peculiar properties. In like
manner, as Davy has observed, when water is added in certain
quantities to Libavius's liquor (_deutochloride of tin_), a solid
crystalline mass is obtained, from which oxide of tin and muriate
of ammonia can be obtained by ammonia.

In his Elements of Chemical Philosophy, Davy has been, in many
instances, explicit on this point; and his opinions are favourable
to the idea that chlorides become muriates by being dissolved in
water: thus, he states that the perchloride of iron "acts with
violence upon water, and forms a solution of red muriate of iron;"
and he observes that the permuriate "forms a solution of green
muriate of iron by its action upon water."[93] With regard,
however, to the general principle, that chlorides become muriates
by solution, there are difficulties which do not fall within
the province of a biographer to discuss. I shall merely observe
that such a change is, in many cases, so inconsistent with our
preconceived opinions, that very strong evidence is required to
reconcile us to its truth. We are undoubtedly prepared to hear that
much may happen between the cup and the lip,--but that common salt
should be a _chloride of sodium_ on our plates, and a _muriate of
soda_ in our mouths, is certainly a very startling assertion.

  [93] For an admirable paper upon this subject by Mr. R. Phillips,
  in which all the material points of the subject are considered
  with that acumen which distinguishes its author, see Annals of
  Philosophy, vol. i. New Series.

The reception which the chloridic theory met with from the chemical
world might aptly enough be adduced in illustration of that remark
with which I commenced the preceding chapter. At first, its
truth was questioned, and no sooner had this been triumphantly
established, than an attempt was invidiously made to transfer the
glory of the discovery from Davy to the French philosophers. Upon
each of these points, I shall beg to offer a few observations.

First, with regard to the fact of chlorine being as yet an
undecompounded body. The very announcement of a theory so
adverse to the universal faith of Europe, was a signal for open
hostilities; the observations of Dr. Murray may be considered as
expressing the sentiments of most of the leading chemists on the
first publication of the novel views of Davy. "Opinions," says
he, "more unexpected have seldom been announced to chemists, than
those lately advanced by Mr. Davy with regard to the constitution
of the muriatic and oxymuriatic acids; _viz._ that the latter is
not a compound of muriatic acid and oxygen, but a simple substance,
and that the former is a compound of this substance with hydrogen.
The more general principle connected with these opinions, that
oxymuriatic acid is, like oxygen, an acidifying element, forming
with inflammables and metals an extensive series of analogous
compounds, leads still more directly to the subversion of the
established chemical systems, and to an entire revolution in some
of the most important doctrines of the science."

Dr. Murray entered the lists as the avowed partisan of the theory
of Berthollet; Dr. Davy, on the other hand, appeared as the
champion of his brother's doctrine. A severe contest ensued, and
both combatants displayed equal skill and strength. The object
of the former was to demonstrate the presence of water, or its
elements, as a constituent part of muriatic acid; and he proposed
to determine the point by combining the dry gases of muriatic acid
and ammonia; for as these bodies did not contain its elements,
should water appear, he maintained that it must be considered as
pre-existing in the muriatic acid; while, on the contrary, if no
water could be procured, it would be unphilosophical to suppose
it present, but that muriatic acid gas must, in that case, be
considered as a compound of hydrogen and chlorine. In performing
this experiment, Dr. Murray did succeed in obtaining a portion of
water; but the inference from such a fact was questioned on the
other side, upon the assumption of the humidity of the gases. As
all parties, however, seemed to agree, that if every source of
error could be excluded, the combination of these gases would
furnish an _experimentum crucis_, by which the truth or fallacy
of either theory might be established, Davy, when at Edinburgh,
was desirous of repeating the experiment with Dr. Hope, and it was
accordingly made in the College Laboratory. Sir George Mackenzie,
Mr. Playfair, and some other gentlemen, were present. The results
were communicated in Nicholson's Journal by Dr. Davy, and may be
briefly stated as follows:--The alkaline and acid gases were pure,
and both had been previously dried by exposure for sixteen hours
to substances having a strong attraction for water. The apparatus
consisted of a plain retort of about the capacity of twenty-six
cubic inch measures, with a stop-cock; and of a receiver, with a
suitable stop-cock. The latter was filled over mercury with one
of the gases, which from the receiver passed into the exhausted
retort by means of the stop-cocks; the other gas was introduced the
same way into the retort; and thus alternately about ninety cubic
inches of each gas were combined. All the salt having then been
driven into the bulb of the retort by the heat of a spirit lamp,
the neck was cooled and kept cold by moistened cloths, whilst the
bulb was heated by a coke fire, till the muriate began to sublime,
and to make its appearance at the curvature of the vessel when
the fire was withdrawn. The result was then examined, while the
bottom of the retort was still very hot: a dew, just perceptible,
was observed lining the cold neck. The quantity of water was so
extremely small, that the globular particles composing this dew
could scarcely be perceived by the naked eye; now the quantity
of water, according to hypothesis, should equal no less than
eight grains. There is no small difference, it must be confessed,
between that quantity and a dew barely perceptible, and which may
reasonably be referred to a minute quantity of vapour in the gases,
or to a little moisture derived from the mercury, a small quantity
of which entered the retort with the gases. Dr. Hope wished to
ascertain how much water would produce such a dew as was observed.
For this purpose he heated in a retort, of a similar size to that
used in the experiment, a single drop of water, which it may be
said weighs about a grain. The appearance of condensed water, in
this instance, in the neck of the retort, was much greater than in
the preceding: he considered it as being three or four times as
great.[94]

  [94] Sir Humphry Davy, during some experiments on the diamond,
  subsequently ascertained that less than 100th of a grain of water
  is sufficient to produce a sensible dew on a polished surface.

From these results it may be concluded, on Dr. Murray's own ground
of reasoning, that water is not a constituent part of muriatic
acid gas, and that this substance is a compound merely of chlorine
and hydrogen; for it is easy to account for the presence of about
one-third of a grain of water from various sources, while it is
impossible to account for the absence of eight grains upon any
theory except that which supposes the gas to be _anhydrous_.

I shall not pursue the numerous other experiments by which it was
attempted to prove the fallacy of Davy's views; they all turn upon
the same point, and were refuted by the same vigorous methods of
enquiry. The chloridic theory may therefore now be considered as
fully established: the philosophers who were for so long a period
hostile to its reception, have at length yielded their assent; and
Berzelius, in a paper published in the "Annales de Chimie," on the
subject of sulpho-cyanic acid, has unconditionally tendered his
allegiance; while the subsequent discovery of iodine and bromine
has confirmed, by the most beautiful analogies, the views so
satisfactorily explained by experiment.

As to the claim of priority which has been urged by several
philosophers in favour of the French chemists, Davy, in speaking
of Gay Lussac's paper, published in the "Annales de Chimie" for
July 1814, observes, that "the historical notes attached to it are
of a nature not to be passed over without animadversion. M. Gay
Lussac states, that he and M. Thénard were the first to advance
the hypothesis that chlorine was a simple body; and he quotes M.
Ampère as having entertained that opinion before me. On the subject
of the originality of the idea of chlorine being a simple body, I
have always vindicated the claims of Scheele; but I must assume
for myself the labour of having demonstrated its properties and
combinations, and of having explained the chemical phenomena it
produces; and I am in possession of a letter from M. Ampère, that
shows he has no claims of this kind to make."[95]

  [95] Royal Institution Journal, vol. i. p. 283.

The question of priority appears to me to be readily settled by a
reference to printed documents. Davy published his "Elements of
Chemical Philosophy" in 1812, containing a systematic account of
his new doctrines concerning the combinations of simple bodies.
Chlorine is there placed in the same rank with oxygen, and finally
removed from the class of acids. In 1813, M. Thénard published
the first volume of his "Traité de Chimie Elémentaire Théorique
et Pratique," in which he states the composition of oxymuriatic
acid as follows:--"_Composition_. The oxygenated muriatic gas
contains the half of its volume of oxygen gas, not including that
which we may suppose in muriatic acid." It was not until the year
1816, that, by a note in his fourth volume, he appears to have
at all relaxed in his attachment to the old theory of Lavoisier
and Berthollet; and it will presently appear, that at the period
above mentioned, iodine had been discovered, and its analogies to
chlorine fully established, by the sagacity of Davy.

Having, as I trust, offered an impartial view of his claims to the
establishment of the chloridic theory, I shall resume my narrative
of those events which more immediately connect themselves with his
personal history at this period.

The great fame of Davy, and the high importance of the discoveries
which had bestowed it, became a general theme of admiration
throughout the scientific circles of Europe, and induced the
members of the Dublin Society to invite him to that city, for the
purpose of delivering a course of lectures. From the authentic
documents which have been placed in my hands, I am enabled to give
a particular account of this transaction.

At a meeting of the Dublin Society held on the 3rd of May 1810,
the following Resolutions were proposed and unanimously carried,
_viz._

1. "That it is the wish of the Society to communicate to the
Irish public, in the most extended manner consistent with the
other engagements of the Society, the knowledge of a Science so
intimately connected with the improvement of Agriculture and the
Arts, which it is their great object to promote; and that, with
this view, it appears to them extremely desirable to obtain the
fullest information respecting the recent discoveries made by Mr.
Davy, in Electro-chemical science.

2. "Resolved, That application be made to the Royal Society,
requesting that they will be pleased to dispense with the
engagements of Mr. Davy, so far as to allow the Dublin Society to
solicit the favour of his delivering a course of Electro-chemical
Lectures in their new Laboratory, as soon as may be convenient
after their present course of chemical lectures shall have been
completed by their Professor Mr. Higgins.

3. "That the sum of four hundred guineas be appropriated out
of the funds of the Society, to be presented to Mr. Davy, as a
remuneration for the trouble and expense which they propose he
should incur, and as a mark of the importance they attach to the
communication which they solicit."

Mr. Leslie Foster having stated to the Dublin Society that the
"Farming Society of Ireland" were desirous of availing themselves
of this opportunity to apply to Mr. Davy to repeat before them
the six lectures on the application of chemistry to agriculture,
which he delivered this year (1810) to the Board of Agriculture
in England, and that they requested the Dublin Society would
accommodate them with the use of their Laboratory for that purpose,
all the members of the Dublin Society having free admission to such
lectures--

The following Resolutions were passed by the Dublin Society:--

"That in the event of Mr. Davy coming over to Ireland, and
consenting to deliver the Course referred to, the Farming Society
shall be accommodated with the use of the Laboratory, according to
their request.

"That it be referred to the Committee of Economy to consider on
what terms, and under what regulations, it may be expedient to
issue tickets of admission to the Electro-chemical Course, so as to
reimburse to the Society the expenses attendant on the arrangement;
and that, in order to give the fullest effect to such regulations,
the members of the Society renounce any claim to gratuitous
admission to this course."

A letter having been addressed to Mr. Davy by the Secretary of the
Society, inviting him to Dublin, for the purpose of delivering
courses of lectures, in conformity with the foregoing resolutions,
the following answer was received from him:--


    TO JOHN LESLIE FOSTER, ESQ. M. P. SECRETARY TO THE DUBLIN SOCIETY.

    May 30, 1810.

    SIR,

    I had the honour of communicating your letter to the President
    and Council of the Royal Society, who have desired me to express
    to you, Sir, and through you, to the Dublin Society, the lively
    interest they feel in the prosperity of that useful public body,
    and the desire that they have to promote its important object.

    On these grounds, they have been pleased to permit me to be absent
    from the meetings of the Royal Society, during the period that may
    be necessary for delivering a Course of Lectures at the Laboratory
    of the Dublin Society, in the month of November next.

    Be pleased to express to the Dublin Society my grateful
    acknowledgments for the honour they have done me in making such a
    proposition; and assure them that I shall use my best exertions
    to promote their views for the extension of Chemical Science, and
    every other species of useful knowledge.

    I beg to be permitted to thank you, Sir, for the flattering manner
    in which you had the goodness to convey to me their proposal.

    I am, Sir, with great respect,

    Your obliged and obedient servant,

    H. DAVY, SEC. R. S.


On the commencement of the Course, on the 8th of November 1810,
three hundred and seventy-one admission tickets had been issued;
and the Committee of Chemistry having expressed their opinion to
the Society, that the lecture-room would not afford accommodation
for a greater number of persons, the Assistant Secretary was
directed to limit his tickets to that number. On the 15th instant,
however, the number was increased to four hundred, without
inconvenience.

At the close of the Course, on the 29th of November, the Dublin
Society passed the following Resolutions:--

"Resolved, That the thanks of the Society be communicated to
Mr. Davy for the excellent Course of Lectures which, at their
request, has been delivered by him in their Laboratory; and to
assure him that the views which led the Society to seek for these
communications, have been answered even beyond their hopes;--that
the manner in which he has unfolded his discoveries has not merely
imparted new and valuable information, but further appears to
have given a direction of the public mind towards Chemical and
Philosophical enquiries, which cannot fail in its consequences to
produce the improvement of the Sciences, Arts, and Manufactures in
Ireland.

"That the thanks of the Society be communicated to the Royal
Society for their ready compliance with our request, in dispensing
with the engagements of Mr. Davy, during the last six weeks.

"That Mr. Davy be requested to accept the sum of five hundred
guineas from the Society."[96]

  [96] There were four hundred tickets issued for the Course, sixty
  of which were honorary; the produce of the remainder amounted to
  672_l._ 5_s._ 3_d._ Davy received 525_l._; and the surplus went
  to officers and servants, and for the discharge of incidental
  expenses.

The following letter appears, from the date, to have been written
about a week before his arrival in Dublin.


    TO THOMAS POOLE, ESQ.

    October 12, 1810.

    MY DEAR POOLE,

    Upon every occasion your recommendation, or opinion, would have
    great weight with me.

    Amongst the candidates for the office of Clerk to the Royal
    Society, there is one Mr. W----, that I am well acquainted with,
    and who was formerly attached to the Royal Institution. He appears
    to me, as well from his scientific character, as from his habits
    and pursuits, to be admirably fitted for the situation. I advised
    him nearly two months ago, in consequence of a conversation with
    Sir Joseph Banks, to offer himself for the situation. I cannot
    therefore interest myself for any other person who does not possess
    superior qualifications.

    Sir Joseph's maxim, which I hope will be adopted by all the
    members, is--"let it be given to the most worthy." I have no doubt
    that Mr.---- would fill the situation with credit, and that he
    is a very worthy man; but, from all that I can learn, his claims
    are much inferior to those of W----. We want not merely a civil,
    gentlemanlike, honest man, but a man a little accustomed to
    calculation, to astronomical observation, and to experiment.

    I am in a delightful country here--the Valley of the Tyne--enjoying
    a few days' leisure after a rather hard chemical campaign, and
    preparing health and spirits for another in Ireland, where I am
    going next week.

    I hope to be in London by the first week in December. I intend next
    summer to go into Cornwall--God willing; and I will not go through
    without seeing you, and telling you that, under all circumstances,
    I shall always think of you with the warmest esteem, and shall
    always be

    Your sincere friend,

    H. DAVY.


In the following year, Davy was again solicited by the Dublin
Society to deliver lectures in their laboratory; and at a meeting
of the members on the 13th of June 1811, a series of resolutions
were passed, by which he was empowered to procure copies of many
of the geological sketches referred to in a course of lectures he
had delivered on Geology at the Royal Institution; and also to
superintend the construction of a large Voltaic battery, for the
illustration of the proposed lectures.

In compliance with this request, Davy delivered two distinct
courses; one on the Elements of Chemical Philosophy, the other on
Geology, for which he received the unanimous thanks of the Society,
and as a more substantial testimony of their gratitude, the sum[97]
of seven hundred and fifty pounds; the receipt of which Davy
acknowledged by the following letter.

  [97] These Courses were more numerously attended than those in
  1810, there having been issued about five hundred and twenty-five
  tickets; the proceeds of which were 1101_l._ 2_s._


    TO B. MAC CARTHY, ESQ. ASSISTANT SECRETARY TO THE DUBLIN SOCIETY.

    Dublin, December 9, 1811.

    SIR,

    I have received your letter, inclosing a draught for seven hundred
    and fifty pounds Irish.

    I am very much gratified by the thanks of the Dublin Society, for
    the courses of lectures which I had the honour of delivering in
    their laboratory; and I am proud of their opinion, that they will
    be useful to the Irish public.

    The attention, candour, and indulgence with which they were
    received by the audience, I shall remember with the warmest
    feelings of gratitude as long as I live.

    I have the honour to be, Sir, with much esteem, your obliged and
    obedient servant,

    H. DAVY.


Before he quitted Dublin, the Provost and Fellows of Trinity
College conferred upon him the honorary degree of LL.D., as an
expression of the high admiration which his eminent scientific
merits had so universally commanded.

In the month of August, in the same year, his opinion was requested
by a committee, as to the best method to be adopted for ventilating
the House of Lords; to which circumstance he alludes in the
following note to his friend Mr. Pepys.


    August 10, 1811.

    MY DEAR PEPYS,

    I find that I am engaged on Wednesday, to meet Lord Liverpool, at
    the House of Lords, to consider a mode of ventilating it.

    This business, most unluckily, will prevent my accompanying you;
    but I shall be glad to go with you on some other day, and to touch
    up the trout at Cheynies, and afterwards to proceed to Serge Hill.

    Very affectionately yours,

    H. DAVY.


This undertaking, it must be allowed, was on Davy's part a most
complete failure: whether he had miscalculated the diameter and
number of the apertures necessary for establishing a current, it
is difficult to say, but it was obvious that the stream of fresh
air thus introduced was by no means adequate to the demand for
it.[98]

  [98] In February 1812, he exhibited a model, in one of his
  lectures at the Royal Institution, in illustration of his plan;
  from which it appeared that the air deteriorated by respiration
  was conducted through three copper pipes, terminating in a single
  tube, to the roof of the building; and by means of ventilators
  below, there was a constant supply of fresh air, the circulation
  of which was promoted by a furnace.

The failure, so vexatious to Davy, became to others a fertile
source of pleasantry, and numerous epigrams, not exactly of a
character to meet the public eye, were very generally circulated,
and which, in recording the miscarriage of science, displayed the
triumph of wit.

The scientific renown of Davy having attracted the attention of
his late Majesty, at that time Prince Regent, he received from his
Royal Highness the honour of Knighthood, at a levee held at Carlton
House, on Wednesday, the 8th of April 1812; and it may be remarked,
that he was the first person on whom that honour had been conferred
by the Regent.

On the day following this occurrence, Sir Humphry delivered his
farewell lecture before the members of the Royal Institution;
for he was on the eve of assuming a new station in society,
which induced him to retire from those public situations which
he had long held with so much advantage to the world, and with
so much honour to himself. How far such a measure was calculated
to increase his happiness I shall not enquire; but I am bound to
observe, that it was not connected with any desire to abandon the
pursuit of science, nor even to relax in his accustomed exertions
to promote its interests. It was evident, however, to his friends,
that other views of ambition than those presented by achievements
in science, had opened upon his mind: the wealth he was about to
command might extend the sphere of his usefulness, and exalt him
in the scale of society: his feelings became more aristocratic, he
discovered charms in rank which had before escaped him, and he no
longer viewed Patrician distinction with philosophic indifference.

On the 11th of April 1812, Sir Humphry married Mrs. Apreece, the
widow of Shuckburgh Ashby Apreece, Esq. eldest son of Sir Thomas
Apreece: this lady was the daughter and heiress of Charles Kerr, of
Kelso, Esq. and possessed a very considerable fortune.

Immediately after the celebration of the marriage, Sir Humphry and
his bride proceeded to the hospitable mansion of Sir John Sebright,
and afterwards made a tour through Scotland, receiving wherever
they went the most flattering marks of attention.

During their excursion, Davy wrote various letters to his
scientific friends, several of which I shall introduce; but,
in order that those to Mr. Children may be understood, it will
be necessary that the reader should be made acquainted with a
transaction which occurred in the year 1811.

In consequence of some conversation on gunpowder, during which
Davy observed that its composition might be greatly improved
by rendering it less _hygrometric_, a proposition was started,
that he should join Mr. Children and Mr. Burton in establishing
a manufactory for its preparation upon chemical principles.
Whether Davy considered himself, in the strict commercial sense,
a partner, or merely a chemical adviser, it is perhaps not easy
to determine; but it is quite clear that both Mr. Children and
Mr. Burton considered him in the former light, although it is an
act of justice to those gentlemen to state, that the very moment
Davy expressed his disinclination to such an arrangement, they
immediately, without the slightest hesitation, released him from
all responsibility. This I am enabled to assert, after a most
careful investigation of all the correspondence that passed upon
the occasion.


    TO JOHN GEORGE CHILDREN, ESQ.

    Harewood House, July 14, 1812.

    MY DEAR FRIEND,

    I am very sorry that I missed you the day before I set out on my
    journey. You will have learnt from your solicitor that I signed the
    articles. I still think I shall return before any powder will be
    made, at least if you do not make it till December, for our present
    intention is to be in town early in that month.

    I sent to you an imperfect copy of my book,[99] in which there were
    no engravings, and in which one cancel was not inserted, thinking
    that you would prefer a copy sent in that way: the cancelled
    leaf, which you have not, contains a correction for the quantity
    of nitrous acid gas and water to form the crystalline compound,
    which is the base of oil of vitriol. Three parts nitrous acid gas
    condense four parts sulphurous gas.

    I have my little apparatus, which will enable me to pursue my
    experiments on gunpowder. There is one conclusion very obvious
    resulting from the new facts,--a _perfect_ gunpowder ought to
    contain no more charcoal than is necessary to convert the oxygen of
    the nitre into carbonic acid. Sulphur forms from nitre just as much
    elastic fluid as charcoal, _i. e._ if similar quantities of nitre
    be entirely decomposed, one by charcoal, and one by sulphur, and
    if the sulphurous gas and the carbonic acid gas be compared, their
    volumes will be equal. The advantage of forming carbonic acid gas
    is, that it is more readily disengaged from the alkali. Now it is a
    question, whether sulphur will decompose _sulphate_ of potash,--it
    will decompose the carbonate; of this we are sure.

    There ought, then, to be just as much sulphur as will form
    sulphuret of potash with the potash: 191 of nitre, 28·5 of
    charcoal, and 30 of sulphur, are the true proportions for forming
    nothing but sulphuret of potash and elastic matter.

    Pray send me some cards to circulate; address to me, Post Office,
    Edinburgh. I hope you got Cavendish's balance.

    I have been here for two days:--it is a very magnificent place:
    good fishing for pike, trout, and grayling. Lady D. desires her
    kind remembrances.

    I am, my dear friend,

    Most affectionately yours,

    H. DAVY.

  [99] "Elements of Chemical Philosophy," to be presently noticed.


    TO THE SAME.

    Dunrobin Castle, near Golspie, August 21.

    MY DEAR FRIEND,

    I hope you are making progress in our manufactory. I shall expect,
    on my return, to find your powder the best and strongest, and to
    make trial of it. I wish I had some of it here, the black-cock and
    grouse would feel its efficacy. I have been expecting a letter from
    you every day.

    This house is so delightful, the scenery so grand, and the
    field-sports so perfect, that I think we shall not quit it for a
    fortnight.

    I went to Inverness and fished for salmon. I also went to two or
    three other places, but not one did I catch till I arrived here.
    The first day I landed seven noble ones, and played three more in
    four or five hours. The next day I played eight and landed three,
    besides white trout in abundance.

    I have shot only one day, for a few hours; but we found grouse
    at every fifty yards, and I shot seven. We are just going to try
    sea-fishing.

    Pray write to me a little news of what is doing for science and the
    world.

    I beg you will remember me most kindly to your father and to Dr.
    Babington, and Brande, when you see them.

    I am, my dear friend,

    Most affectionately yours,

    H. DAVY.


    TO WILLIAM CLAYFIELD, ESQ.

    Dunrobin, near Golspie, August 28, 1812.

    DEAR CLAYFIELD,

    I am much obliged to you for two very kind letters, and for a box
    containing specimens from St. Vincent.[100] I beg you will thank
    the gentleman who was so good as to cause them to be collected for
    me. The box followed me to Inverness.

    The ashes, I think, are likely to fertilize Barbadoes. There is
    a parallel case of materials having been carried so far in the
    eruption in Iceland in 1783.

    I have been with my wife making a tour through the North since the
    beginning of July. We have arrived at our extreme point, and shall
    slowly proceed South in about a fortnight.

    I wish you could be of our party here; we are in a delightful
    house, that of Lord Stafford, in a country abounding with fish and
    game. I have caught about thirty salmon since I have been here, and
    killed grouse, wild ducks, teal, &c. I have not yet shot a stag,
    but I hope to do so this next week.

    I have just published a volume of the Elements of Chemistry, and I
    hope to publish another in the course of the Spring.

    Having given up lecturing, I shall be able to devote my whole time
    to the pursuit of discovery.

    I have not sent you a copy of my book, for I have thought that the
    best mode of avoiding giving offence to some, was by not making
    presents at all. Had I not so determined, one of the first copies
    would have been sent to you, as a mark of the warm esteem and
    regard of

    Your affectionate friend,

    H. DAVY.

  [100] Specimens of substances ejected from the crater in that
  island, which Mr. Clayfield forwarded to Davy, in consequence
  of having heard that he had been engaged in examining the sand
  collected at Barbadoes, and which was a product of the same
  eruption.


    TO SAMUEL PURKIS, ESQ.

    Dunrobin Castle, Aug. 29, 1812.

    MY DEAR PURKIS,

    You may probably be surprised to receive a letter from me from this
    remote corner of the North; but I owe you a letter, and I have a
    great inclination, wherever I may be, to discharge all debts, and
    particularly those rendered due by kindness.

    Receive my warm acknowledgments for your kind congratulations on my
    becoming a Benedick. I can now speak from experience, in which you
    have long participated. I am convinced that the natural state of
    domestic society is the best fitted for man, whether he be devoted
    to philosophy, or to active life.

    I shall have much pleasure in presenting my wife to you and to Mrs.
    Purkis, on my return.

    We have had a delightful tour through the Highlands. We are at
    the extreme point of our journey. The pleasures of a refined
    society--that of Lord and Lady Stafford's family--have induced
    us to make a long pause here. We think we shall be in London the
    beginning of December.

    I have spent some days such as we passed together in Wales. We have
    had all the varieties of river, mountain, and wood scenery. The
    Lakes of Scotland are infinitely finer than those of Wales; but
    the glens of the Principality may fairly stand in competition with
    those of the Highlands.

    I hope I shall find you and your family in good health, and that
    you will have spent a very pleasant summer. I am, my dear Purkis,

    Very sincerely and affectionately yours,

    H. DAVY.


    TO JOHN GEORGE CHILDREN, ESQ.

    Dunkeld, Sept. 27, 1812.

    MY DEAR FRIEND,

    I have received your two kind letters. I hope your quiet life, and
    reasonable medical discipline, will entirely restore your health.

    We are now on our return, and probably shall arrive in London
    before the middle of November: our time, however, is uncertain, as
    the Election may hasten, or keep us back for want of horses.

    I can do nothing respecting the licence till my return; I will
    then see Mr. Wharton, or Mr. Vansittart. I have another subject
    of conversation in which they are interested, and I can easily
    introduce that of gunpowder.

    I have been tolerably successful as a shot lately. I have not
    fished. My last adventure was at the Spey, near Gordon Castle,
    where I killed some noble salmon. At Blair Athol I shot some
    ptarmigans and a stag. I am now at Dunkeld, which I think the most
    beautiful habitable spot in the Highlands. The Tay, a noble river,
    rolls with a majestic stream through lofty woods seated upon cliffs
    and rounded hills; and in the background are the Mountains of
    Benyglor and the hills of Killycrankie.

    My wife desires her kind remembrances. Pray offer mine to
    your father and daughter, and believe me to be always most
    affectionately yours,

    H. DAVY.


    TO THE SAME.

    Edinburgh, October 14.

    MY DEAR FRIEND,

    We are on our return: I am well, but I am sorry to say that Lady D.
    is very much indisposed, and anxiety for her hastens my journey to
    town.

       *       *       *       *       *

    I have received a very interesting letter from Ampère. He says
    that a combination of chlorine and azote has been discovered at
    Paris, which is a fluid, and explodes by the heat of the hand; the
    discovery of which cost an eye and a finger to the author. He gives
    no details as to the mode of combining them. I have tried in my
    little apparatus with ammonia cooled very low, and chlorine, but
    without success.

    There is little doing here ... dresses and dances. Sir James Hall
    is writing on a sort of Deluge. Playfair is the true and amiable
    Philosopher. My brother is making experiments on animal matter.

    I hope your gunpowder works are nearly finished. I shall be at the
    opening ball. As soon as I return I shall give my mind up to this
    matter. My wife desires her kind remembrances. Mine to your worthy
    father and Anna.

    God bless you, my dear friend, and believe me

    Ever affectionately yours,

    H. DAVY.


On his return to town, after this tour, the following letter was
addressed to his friend at Tonbridge:--


    October 24, 1812.

    MY DEAR CHILDREN,

    I have just seen Pepys, and rejoice that he gives me so good an
    account of your health. My wife is much better, except that she
    has a swollen foot. I have never seen her in such good health and
    spirits. She is resolved to lead a home life of perfect quiet for
    six weeks, and I fear you will not be able to tempt her to quit her
    fire-side, though there is no visit she would make with greater
    pleasure: but lameness does not suit the country; and for one so
    enthusiastically fond of nature, it would be vexatious to be in the
    country, and not to be able to enjoy hills, and meads, and woods.

    But I am ready to come to my business whenever you think I can be
    useful. I shall set to work to make gunpowder with as much ardour
    as Miles Peter--I hope with similar results.

    I shall not be able to endure a very long separation from my wife,
    but for three or four days I am at your command.

    I have been working yesterday and to-day on some new objects; and
    we are to have a meeting on Wednesday, at one o'clock, at the
    Institution, to try to make this compound of azote and chlorine,
    and to try some other experiments. Afterwards we (Angling Chemists)
    propose a dinner at Brunet's. If you can come to town on that day,
    I will promise to return with you.

    God bless you, my dear Children, and believe me to be most
    affectionately yours,

    H. DAVY.




CHAPTER IX.

   Davy's "Elements of Chemical Philosophy" examined.--His Memoir
   on some combinations of Phosphorus and Sulphur, &c.--He
   discovers Hydro-phosphoric gas.--Important Illustrations of
   the Theory of Definite Proportionals--Bodies precipitated
   from water are Hydrats.--His letter to Sir Joseph Banks on
   a new detonating compound.--He is injured in the eye by its
   explosion.--His second letter on the subject.--His paper on the
   Substances produced in different chemical processes on Fluor
   Spar.--His work on Agricultural Chemistry.


The "Elements of Chemical Philosophy," a work to which he has
alluded in several of the preceding letters, was published in
June 1812. It is dedicated to Lady Davy, to whom he offers it "as
a pledge that he shall continue to pursue Science with unabated
ardour."

This work, although only a small part of the great labour he
proposed to accomplish, must be considered as one of high
importance to the cause of science. It has not perhaps announced
any discoveries which had not been previously communicated to the
Royal Society, but it has brought together his original results,
and arranged them in one simple and digested plan--it has given
coherence to disjointed facts, and has exhibited their mutual
bearings upon each other, and their general relations to previously
established truths.

Very shortly after the publication of this first part, it was
asserted by a scientific critic that the work could never be
completed upon the plan on which it had commenced, which was little
less than a system of chemistry, in which all the facts were to be
verified by the author: an undertaking far too gigantic for the
most intrepid and laborious experimentalist to accomplish. There
was too much truth in the remark:--the life of the Author has
closed--the work remains unfinished.

Although it bears the title of "Elements," its plan and execution
are rather adapted for the adept than the Tyro in science; it has,
however, enabled the discoverer to expand several of his opinions
with a freedom which is not consistent with the studied compression
and elaborate brevity that necessarily characterise the style of
a Philosophical Memoir,--and thus far it may have served the more
humble labourer.

The first impression which this volume must produce, is that of
admiration at the rapid and triumphant progress of Chemistry,
during the period of a very few years; while a comparison of this
work with others, even of very recent date, will show how much we
are indebted for this progress to the unrivalled labours of Davy.

The first part of his projected system, which constitutes the
volume under review, extends only to the general laws of chemical
changes, and to the primary combinations of undecompounded bodies.
It is resolved into seven divisions, upon each of which I propose
to offer some remarks.

THE FIRST DIVISION embraces the consideration of the three
different forms of matter, _viz._ Solidity, Liquidity, and elastic
Fluidity; and that of the active powers on which they depend, and
by which they are changed, such as Gravitation, Cohesion, Calorific
repulsion, or Heat, and Attractions chemical and electrical;--the
laws of which he has expounded in a lucid and masterly manner;
although it will be only necessary to quote the following passage,
to show that the greatest philosopher may occasionally slide
into error. "In solids, the attractive force predominates over
the repulsive; in fluids, and in elastic fluids, they may be
regarded as in different states of equilibrium; and in ethereal
substances, the repulsive must be considered as predominating
over and destroying the attractive force." A reviewer has very
justly observed, that it is difficult to conceive how so much
error and confusion could have been collected, by such an author,
into so short a sentence. It is a solecism to say that two forces
may exist in different states of equilibrium; besides, it is
generally admitted that the repulsive force alone exists in elastic
fluids, and that it is only compensated by external pressure, or
gravitation.

In treating the subject of Heat, he maintains the same
opinion, though in a manner somewhat more subdued, as that
which he had formed at the very commencement of his scientific
career,[101]--that it is nothing else than motion, and that the
laws of Heat are the same as the laws of Motion.

  [101] See Page 44.

In taking a general view of the subject of Chemical Attraction,
there is a remarkable clearness in his enunciation of its several
propositions, and a great felicity in the selection of its
illustrations. He combats the theory of Berthollet, respecting the
influence of mass, with singular success, and confirms the general
law, that all bodies combine chemically, in certain definite
proportions to be expressed by numbers; so that, if one number be
employed to denote the smallest quantity in which a body combines,
all other quantities of the same body will be as multiples of this
number; and the smallest proportions in which the undecompounded
substances enter into union being known, the constitution of the
compound they form may be learnt; and the element which unites
chemically in the smallest quantity being expressed by unity, all
the other elements may be represented by the relations of their
quantities to unity. Unfortunately, however, there has existed
amongst philosophers a want of agreement as to the _unit_ to which
the relative values of the other numbers shall be referred. Mr.
Dalton selected Hydrogen as the unit; Davy followed his example,
but doubled the weight of oxygen; while Wollaston, Thompson, and
Berzelius, have proposed oxygen as the most convenient unit, since
that element enters into the greatest number of combinations.

To Dalton is now universally conceded the glory of having
established the laws of definite proportions; but in unfolding
them, he has employed expressions which involve speculations as
to their physical cause, and has thus given to that, which is
nothing more than a copious collection of facts, the appearance
of a refined theory. It may be perfectly true, as Mr. Dalton
supposes, that all bodies are composed of ultimate atoms; but in
the present state of our knowledge, we can neither form any idea
of the nature of such atoms, nor of the manner in which they may
be grouped together. We are therefore indebted to Davy for having,
by his early and powerful example, taught the chemist how to
disentangle fact from hypothesis, and to investigate the doctrine
of proportionals, without any reference to the _atomic_ theory
which has been proposed for its explanation.

THE SECOND DIVISION treats of Radiant or Ethereal Matter, and
of its effects in producing vision, heat, and chemical changes.
It contains some refined speculations respecting the possible
conversion of terrestrial bodies into light and heat, and _vice
versâ_.

THE THIRD DIVISION presents us with an account of "Empyreal
undecompounded Substances," or those which support combustion;
together with that of the compounds which they form with each
other. Upon this occasion, Davy has completely rescued us from
the trammels of the Anti-phlogistic theory, and has shown that,
so far from the process of combustion depending upon the position
or transfer of oxygen, it is a _general_ result of the actions
of _any_ substances possessed of strong chemical attractions, or
different electrical relations, and that it takes place in all
cases in which an intense and violent motion can be conceived
to be communicated to the corpuscules of bodies, without any
regard to the peculiar nature of the substances engaged. The
announcement of the general law is followed by a history of the
only two undecompounded bodies included under this arrangement,
viz. _Oxygen_, and _Chlorine_.[102] In naming a class of bodies
by their relations to combustion, he distinctly states that he
merely intends to signify that the production of heat and light is
more characteristic of their actions, than of those of any other
substances; and that they are, at the same time, opposed to all
other undecompounded substances by their electrical relations,
being always in Voltaic combinations attracted to, or elicited
from the positive surface; whereas all other known undecompounded
substances are separated at the negative surface.

  [102] _Iodine_, _Fluorine_, &c. had not been discovered at this
  period.

THE FOURTH DIVISION comprises the history of Undecompounded
Inflammables, or Acidiferous Substances, not Metallic, and that of
their binary combinations with oxygen and chlorine, or with each
other.

The bodies considered under this division, are the
following:--Hydrogen, Azote, Sulphur, Phosphorus, and Boracium, or
Boron. Under the history of Sulphur, he gives us the true theory of
the process by which sulphuric acid is produced by the combustion
of that body in mixture with nitre, and which had never before been
explained in any chemical work.

THE FIFTH DIVISION contains the Metals; their primary combinations
with other undecompounded bodies, and with each other.

In the order of classification adopted on this occasion, the newly
discovered inflammable metals, producing by combustion alkalies,
alkaline earths, and earths, commence the series; next come those
which produce oxides; and lastly, those which produce acids. Thus
are we presented with a chain of gradations of resemblance which
may be traced throughout the whole series of metallic bodies.

THE SIXTH DIVISION comprehends certain bodies (the _Fluoric
Principle_, and the _Ammoniacal Amalgam_) which present some
extraordinary and anomalous results. It is worthy of remark, that,
at the period at which this work was written, Davy considered the
peculiar acid developed from fluor spar, by the action of sulphuric
acid, as a compound of an acid unknown in a separate state, and
water; whence he proposed to call it _Hydro-fluoric_ acid,--a
term extremely objectionable from its ambiguity, since it would
indicate either hydrogen or water as one of its constituents.
At the conclusion, however, of this chapter, in consequence of
having observed certain phenomena displayed by this gas, when in
combination with silica and boracic acid, he for a moment seems to
have caught the truth, but it as quickly eluded his grasp, and he
dismisses the conjecture which it was his good fortune some years
afterwards to verify, _viz._ that the fluoric acid is a compound
of an unknown principle, analogous to chlorine, with hydrogen and
water, and that _fluor spar_ is a compound of the same principle
with calcium, or the base of lime.

THE SEVENTH DIVISION offers to the chemical enquirer various
speculations, as to the probable nature of certain bodies hitherto
undecompounded. He observes, that "we know nothing of the true
elements belonging to nature; but as far as we can reason from
the relations of the properties of matter, that hydrogen is the
substance which approaches nearest to what the elements may be
supposed to be. It has energetic powers of combination, its parts
are highly repulsive of each other, and attractive of the particles
of other matter; it enters into combination in a quantity very
much smaller than any other substance, and in this respect it
is approached by no known body. After hydrogen, oxygen perhaps
partakes most of the elementary character: it has a greater energy
of attraction, and, with the exception just stated, enters into
combination in the smallest proportion."

In conclusion, he hints at the possibility of the same ponderable
matter in different electrical states, or in different arrangements,
constituting substances chemically different, and he thinks
that there are parallel cases in the different states in
which bodies are found connected with their different relations to
temperature: thus, steam, ice, and water, are the same ponderable
matter; and certain quantities of steam and ice mixed together
produce ice-cold water.

"That the forms of natural bodies may depend upon different
arrangements of the same particles of matter, has been a favourite
hypothesis, advanced in the earliest era of physical research,
and often supported by the reasonings of the ablest philosophers.
This sublime chemical speculation, sanctioned by the authority
of Hooke, Newton, and Boscovich, must not be confounded with the
ideas advanced by the alchemists, concerning the convertibility
of the elements into each other. The possible transmutation of
metals has generally been reasoned upon, not as a philosophical
research, but as an empirical process. Those who have asserted the
actual production of the precious metals, or their decomposition,
or who have defended the chimera of the philosopher's stone, have
been either impostors, or men deluded by impostors. In this age
of rational enquiry, it will be useless to decry the practices
of the adepts, or to caution the public against confounding the
hypothetical views respecting the elements founded upon distinct
analogies, with the dreams of alchemical visionaries, most of whom,
as an author of the last century justly observed, professed an art
without principles, the beginning of which was deceit, and the end
poverty."

On the 18th of June 1812, Davy presented to the Royal Society a
paper entitled "On some Combinations of Phosphorus and Sulphur; and
on some other subjects of Chemical Inquiry."

By the researches detailed in this Memoir, he accomplished
three important objects: he established the existence of some
new compounds--furnished additional evidence in support of the
doctrine of definite proportions--and ascertained that most of the
substances obtained from aqueous solutions by precipitation, are
compounds of water, or _Hydrats_. In the first place, he recognised
the formation of two distinct compounds of phosphorus and chlorine:
one, solid, white, and crystalline in its appearance; the other,
fluid, limpid as water, and volatile. The latter body he found to
contain just double as much chlorine as the former.

On experimenting upon this latter body with water, he obtained a
crystallized substance which he proposed to call _Hydro-phosphorous
acid_, since it consists of pure phosphorous acid and water. By
decomposition in close vessels, it is resolved into phosphoric
acid, and a peculiar gas, consisting of one proportional of
phosphorus and four of hydrogen, and for which he proposed the term
_Hydro-phosphorous_ gas. The reader, no doubt, will be immediately
struck with the impropriety of a nomenclature in which the prefix
_Hydro_ is made to express water in the former, and hydrogen in the
latter instance.

In examining the results of the mutual decomposition of water and
the phosphoric compounds of chlorine, Davy remarks, that it is
scarcely possible to imagine more perfect demonstrations of the
laws of definite combination: no products are formed except the
new combinations, (phosphoric acid from the solid, phosphor_ous_
acid, from the liquid compound, and in both muriatic acid;)
neither oxygen, hydrogen, chlorine, nor phosphorus, is disengaged;
and therefore the ratio in which any two of them combine being
known, the ratio in which the rest combine, in these cases, may be
determined by calculation.

Lastly, he ascertained that most of the substances obtained by
precipitation from aqueous solutions are compounds of water: thus
zircona, magnesia, and silica, when precipitated and dried at 212°,
still contain definite proportions of water; and many of the
substances which had been considered as metallic oxides, he found,
when obtained from solutions, to agree in this respect; and that
their colours and other properties are materially influenced by
this combined water.

On the 5th of November 1812, was read before the Royal Society a
letter addressed by Davy to Sir Joseph Banks, on the subject of the
detonating compound already alluded to in his communications to
Mr. Children. He expresses his anxiety to have the circumstances
made public as speedily as possible, since experiments upon the
substance may be connected with very dangerous results.

He had some time before received information from Paris of a
combination having been effected between chlorine and azote, and
that it was distinguished by detonating properties; but he was
wholly ignorant of the mode by which it had been prepared, and he
could not obtain any information upon this point from any of the
French journals.

So curious and important a result could not fail to interest him,
as he had himself been long engaged in experiments on the action
of azote and chlorine, without gaining any decided proofs of
their power of combining with each other. It was evident from the
notice, that this new body could not be formed in any operations
in which heat is concerned; he therefore attempted to combine the
elements by presenting them to each other artificially cooled, the
azote being in a nascent state. For this purpose he introduced
chlorine into a solution of ammonia; a violent action ensued, and
minute films of a yellow colour were observed on the surface of
the liquor, but they immediately resolved themselves into gas. As
he was about to repeat the experiment with some other ammoniacal
compounds, Mr. Children reminded him of the circumstance which he
had previously communicated to him in a letter, that Mr. James
Burton, junr, on exposing chlorine to a solution of nitrate of
ammonia, had observed the formation of a yellow oil, but which he
had not been able to collect. Davy availed himself of the hint, and
obtained the substance in question: on examining its properties by
the application of heat, the tube in which it was contained was
shivered to atoms by its explosion, and he received a severe wound
in the transparent cornea, which was followed by inflammation, and
disabled him from pursuing his enquiry.

In the following July, however, he communicated in a second
letter to Sir Joseph Banks, the continuation of this enquiry, and
furnished a full and satisfactory history of the body in question.
Having procured it in sufficient quantity, he attempted to effect
its analysis by the action of mercury, but a violent detonation
occurred, and he was again wounded in the head and hands;
fortunately, however, the injury was slight, in consequence of his
having taken the precaution to defend his face by a plate of glass
attached to a proper cap.

In a subsequent experiment, by using smaller quantities, and
recently distilled mercury, he succeeded in obtaining results
without any violence of action: the mercury united with the
chlorine, and the azote was disengaged; from which he was enabled
to conclude that it was composed of four volumes of chlorine and
one volume of azote. For this new body Davy suggested the name of
_Azotane_; but I have already observed, that his nomenclature of
the compounds of chlorine has never been adopted; the detonating
substance is now very properly denominated _Chloride of Nitrogen_.

Shortly after the publication of this paper, M. Berzelius, in a
letter to Professor Gilbert, asserted that "_Azotane_" is nothing
more than _dry_ nitro-muriatic acid, since it dissolves slowly in
water, and forms a weak _aqua regia_. "These few observations,"
says he, "show clearly that Davy's analysis of this substance is
inaccurate, and that he corrected his results in consequence of
theoretical views."

This was an imputation upon the philosophical character of Davy,
which excited in him no small degree of indignation. In reply
he says, "It is difficult to discover what meaning M. Berzelius
attaches to the term _dry_ nitro-muriatic acid; and it is wholly
unnecessary to refute so unfounded and vague an assertion."

On July 8, 1813, a paper was read by Davy before the Royal Society,
entitled "Some Experiments and Observations on the Substances
produced in different chemical processes on Fluor Spar."

The views which he formerly entertained with respect to the fluoric
acid have been already noticed:[103] in the present paper he
renounces his previous opinions, and establishes, by experiments
of the most satisfactory character, that the base of fluoric acid
is a highly energetic body not hitherto obtained in an insulated
form, and the properties peculiar to which are as yet unknown. It
appears, however, to belong to the class of negative electrics,
and, like oxygen and chlorine, to have a powerful affinity for
hydrogen and metallic substances. With hydrogen, it constitutes
the peculiar and very powerful acid long known by the name of
_fluoric acid_,--with boron, the _fluoboric_, and with silicium,
the _silicated-fluoric_, acids. Although this theory had originally
suggested itself to the mind of Davy, yet the chemical world is
unquestionably indebted to M. Ampère for establishing it; and
the English chemist has very justly acknowledged the obligation.
"During the period that I was engaged in these investigations,"
says he, "I received two letters from M. Ampère, of Paris,
containing many ingenious and original arguments in favour of the
analogy between the muriatic and fluoric compounds. M. Ampère
communicated his views to me in the most liberal manner: they
were formed in consequence of my ideas on chlorine, and supported
by reasonings drawn from the experiments of MM. Gay Lussac and
Thénard."

  [103] See page 364.

It has been stated that Davy gave his last public lecture on the
9th of April 1812; he however afterwards delivered an occasional
lecture to the Managers, on his own discoveries, and did not
formally resign his professorship until the next year.

The following record has been extracted from the Journal of the
Institution.

       *       *       *       *       *

"Minutes of the Proceedings of a general Monthly Meeting of the
Members of the Royal Institution, held on Monday, April 5, 1813.

"Earl of Winchelsea, President, in the Chair.

"This being the meeting appointed by Article 2. chap. xix. of the
bye-laws, for putting in nomination from the chair the professors
for the year ensuing, Sir Humphry Davy rose, and begged leave to
resign his situation of Professor of Chemistry; but he by no means
wished to give up his connection with the Royal Institution, as he
should ever be happy to communicate his researches, in the first
instance, to the Institution, in the manner he did in the presence
of the members last Wednesday, and to do all in his power to
promote the interest and success of this Institution.

"Sir H. Davy having retired, Earl Spencer moved, That the thanks
of this Meeting be returned to Sir H. Davy, for the inestimable
services rendered by him to the Royal Institution. This motion was
seconded by the Earl of Darnley, and on being put, was carried
unanimously.

"Earl Spencer further moved, That in order more strongly to mark
the high sense entertained by this Meeting of the merits of Sir
H. Davy, he be elected Honorary Professor of Chemistry; which,
on being seconded by the Earl of Darnley, met with unanimous
approbation.

"The Chairman having declared the Professorship of Chemistry
vacant, put in nomination William Thomas Brande, Esq. F.R.S. as a
candidate for that office, with a salary of 200_l._ per annum.

"On Monday, June 7, 1813, William Thomas Brande, Esq. was
unanimously elected."

       *       *       *       *       *

In March 1813, Davy published his "Elements of Agricultural
Chemistry," being the substance of a course of lectures which he
had, for ten successive seasons, delivered before the members of
the Board of Agriculture, to whom the work is inscribed, as a mark
of the author's respect.

This work, which may be considered as the only system of
philosophical agriculture ever published in this country, has not
only contributed to the advancement of science, but to that for
which he has an equal claim upon our gratitude,--the diffusion of
a taste amongst the higher classes for its cultivation; for it
has been wisely remarked, that not he alone is to be esteemed a
benefactor to mankind who makes an useful discovery, but he, also,
who can point out an innocent pleasure.

It has been already stated, that Davy became early impressed
with the importance of the subject:--that in future life its
investigation should have been to him so fertile a source of
pleasure, may be readily imagined, when it is remembered with
what passionate delight he contemplated the ever varying forms of
creation. "I am," said he, "a lover of Nature, with an ungratified
imagination, and I shall continue to search for untasted
charms--for hidden beauties." In unfolding, then, the secrets of
vegetable life, he did but remove the veil from his mistress.
From the same poetical feeling sprang his love of angling: it was
a pursuit which carried him into the wild and beautiful scenery
of Nature, amongst the mountain lakes, and the clear and lovely
streams that gush from elevated hills, or make their way through
the cavities of calcareous strata.[104] In the early spring, it led
him forth upon the fresh turf in the vernal sunshine, to scent the
odour of the bank perfumed by the violet, and enamelled with the
primrose, while his heart participated in the renovated gladness of
Nature.

  [104] See his Salmonia, Edit. 2. p. 9.

I had hoped that, amidst the voluminous correspondence of my late
friend Mr. Arthur Young, some important letters might have been
found from Davy on agricultural subjects; but the communications
which took place between them were generally in conversation, and
I have therefore only been able to procure two letters, which I
shall here insert: the first will show that, during his tours, his
attention was alive to the practices of husbandry; and the second
will prove that he had once seriously contemplated the labour of
writing the agricultural history of his native county.


    TO ARTHUR YOUNG, ESQ.

    Killarney, June 1806.

    DEAR SIR,

    You have been of great and durable service to Ireland. I have met
    with a number of persons who have been enlightened by your labours,
    and who now follow an enlightened system of Agriculture. One very
    intelligent gentleman you will recollect,--Mr. Bolton of Waterford:
    he is zealously pursuing improvements, and is instructing his
    neighbours by precept and example. I am, &c.

    H. DAVY.


The above letter contains also some observations on a chemical
mixture, but which is unintelligible from our being ignorant of the
conversation to which it refers.


    TO THE SAME.

    April, 1807.

    DEAR SIR,

    I called this morning with the hope of seeing you, and of gaining
    some explanation on the subject of your note. I shall not be able
    to leave London until the middle of July, and I must return early
    in October.

    I do not think there would be sufficient time between these periods
    for accomplishing the objects you mention; nor do I think myself
    qualified to write upon the agriculture of a county. I wished
    likewise to devote the leisure of this summer to the preparation of
    my lectures on the Chemistry of Agriculture for publication. I have
    a great deal of information concerning the mineralogy and geology
    of Cornwall, but none concerning the farming.

    If the business admits of being postponed, I might perhaps be able
    to accomplish it next summer; that is, by devoting a part of this
    summer, and the whole of my next: but I would rather confine myself
    to my own province, the mineralogy and geology of the county, and
    leave the agriculture to abler hands.

    Be pleased to receive my thanks, and to communicate them to the
    President for the honour of the proposal. I remain, &c.

    H. DAVY.


The majority of my readers will probably concur in the wisdom of
this decision: they will consider that to have doomed Davy to a
drudgery of this nature, would have been wasting talents upon
an object which might be accomplished by smaller means. From my
acquaintance, however, with Cornwall, I am induced to form a
different opinion. Davy never approached even those subjects which
had already received from others the most thorough investigation,
without extracting from them new and important truths. What, then,
might not have been expected from his genius, when applied to a
department upon which the light of science had scarcely dawned?

It is only in a primitive country like Cornwall, that the natural
relations between the varieties of soil and the subjacent rocks
can be studied with success: as we advance to alluvial districts,
such relations become gradually less distinct and apparent, and are
ultimately lost in the confused complication of the soil itself,
and in that general obscurity which envelopes every object in the
ulterior stages of decomposition. We can, therefore, only hope
to succeed in such an investigation by a patient and laborious
examination of a primitive country, after which we may be enabled
to extend our enquiries with greater advantage through those
regions which are more completely covered with soil, and obscured
by luxuriant vegetation; as the eye, acquainted with the human
figure, on gazing upon a beautiful statue, traces the outline
of the limbs, and the swelling contour of its form, through the
flowing draperies which invest it. The importance of the subject,
as well as the general interest it has excited, induce me to offer
an analysis of his "Elements of Agricultural Chemistry."

The work is divided into eight lectures; and in his introductory
chapter, after adverting to the difficulties which the enquiry
presents to the lecturer, he offers a general view of the objects
of the course, and of the order in which he proposes to discuss
them.

"Agricultural Chemistry has not yet received a regular and
systematic form. It has been pursued by competent experimenters for
a short time only; the doctrines have not as yet been collected
into an elementary treatise; and on an occasion when I am obliged
to trust so much to my own arrangements, and to my own limited
information, I cannot but feel diffident as to the interest that
may be excited, and doubtful of the success of the undertaking. I
know, however, that your candour will induce you not to expect any
thing like a finished work upon a science as yet in its infancy;
and I am sure you will receive with indulgence the first attempt
made to illustrate it, in a distinct course of lectures.

"Agricultural Chemistry has for its objects all those changes
in the arrangements of matter connected with the growth and
nourishment of plants; the comparative values of their produce as
food; the constitution of soils; and the manner in which lands are
enriched by manure, or rendered fertile by the different processes
of cultivation." That such objects are intimately connected
with the doctrines of chemistry, he proceeds to show by several
appropriate and striking illustrations.

"If land be unproductive, and a system of ameliorating it is to
be attempted, the sure method of obtaining the object is, by
determining the cause of its sterility, which must necessarily
depend upon some defect in the constitution of the soil, which may
be easily discovered by chemical analysis. Are any of the salts of
iron present? they may be decomposed by lime. Is there an excess
of siliceous sand? the system of improvement must depend on the
application of clay and calcareous matter. Is there a defect of
calcareous matter? the remedy is obvious. Is an excess of vegetable
matter indicated? it may be removed by liming, paring, and burning.
Is there a deficiency of vegetable matter? it is to be supplied by
manure."

"In the selection also of the remedy, after the discovery of the
evil, chemical knowledge is of the highest importance. Limestone
varies in its composition, and by its indiscriminate application
we may aggravate the sterility we seek to obviate. Peat earth is
an excellent manure, but it may contain such an excess of iron as
to be absolutely poisonous to plants. How are such difficulties to
be met but by the resources of chemistry? It is also evident that
the scientific agriculturist should possess a general knowledge
of the nature and composition of material bodies, and the laws of
their changes; for the surface of the earth, the atmosphere, and
the water deposited from it, must, either together or separately,
afford all the principles concerned in vegetation; and it is only
by examining the chemical nature of these principles, that we are
capable of discovering what is the food of plants, and the manner
in which this food is supplied and prepared for their nourishment."

Davy likewise advocates the necessity of studying "the phenomena
of vegetation, as an important branch of the science of organized
nature; for, although exalted above inorganic matter, vegetables
are yet in a great measure dependent for their existence upon its
laws. They receive their nourishment from the external elements;
they assimilate it by means of peculiar organs; and it is by
examining their physical and chemical constitution, and the
substances and powers which act upon them, and the modifications
which they undergo, that the scientific principles of Agricultural
Chemistry are obtained."

With respect, however, to the practical utility of this latter
branch, different opinions have been entertained. I confess, I am
inclined to agree with an able reviewer[105] when he says, "It
is the proper business of the chemist to examine and ascertain
the nature and properties of dead and inorganized matter, and
the various combinations which, according to chemical laws, it
is capable of forming. The chemical composition of organized
bodies, and of the products which they form, fall likewise under
his cognizance; but when he proceeds to consider the physical
constitution of these bodies, and the manner in which they act in
forming their products, he no longer works with the instruments
of the laboratory, or conducts processes which can be properly
imitated there."

  [105] Edinburgh Review, vol. 22, page 253.

In concluding his introductory observations, he remarks upon the
prejudice which persons, who argue in favour of practice and
experience, very commonly entertain against all attempts to improve
agriculture by philosophical enquiries and chemical methods. "That
much vague speculation may be found in the works of those who
have lightly taken up agricultural chemistry, it is impossible to
deny. It is not uncommon to find a number of changes rung upon a
string of technical terms, such as oxygen, hydrogen, carbon, and
azote, as if the science depended upon words, rather than upon
things. But this is, in fact, an argument for the necessity of the
establishment of just principles of chemistry on the subject.--If a
person journeying in the night wishes to avoid being led astray by
the ignis fatuus, the most secure method is to carry a lamp in his
own hand."

"There is no idea more unfounded than that a great devotion of
time, and a minute knowledge of general chemistry, are necessary
for pursuing experiments on the nature of soils, or the properties
of manures. The expense connected with chemical enquiries is
extremely trifling: a small closet is sufficient for containing all
the materials required."

In the SECOND LECTURE, he enters upon the consideration of the
general powers of matter, such as gravitation, cohesion, chemical
attraction, heat, light, and electricity; and then proceeds to
examine the elements of matter, and the laws of their combinations
and arrangements.

To an audience constituted of persons who were not familiar with
the elementary principles of the science, it might have been very
necessary for the lecturer to enter upon such preliminary details;
but there cannot be any good reason for his having published them
in his system. As they are to be found in every work on chemistry,
it will not be necessary to bestow upon them any further notice.

In the THIRD LECTURE, he enters into a description of the
organization and living system of plants; in which he connects
together into a general view, the observations of the most
enlightened philosophers who have studied the physiology of
vegetation--those of Grew, Malpighi, Sennebier, Hales, Decandolle,
Saussure, Bonnet, Darwin, Smith, and above all, of Mr. Knight,
whose enquiries upon these subjects are not only the latest, but by
far the most satisfactory and conclusive.

As there is little in these descriptions that may not be found in
the original authors, I shall not unnecessarily trespass upon the
time of the reader by relating them. In the latter part of this
lecture, he describes the properties and ultimate composition
of the proximate principles of which vegetable matter consists,
and into which it may be resolved by different processes of art;
such are gum, starch, sugar, albumen, gluten, extract, tannin,
resin, oils, &c. &c. But since the publication of this work,
vegetable analysis has advanced to a degree of refinement which
could scarcely have been anticipated in so short a period, and
consequently many of his statements appear deficient; but his
general directions for conducting an analysis of any vegetable
substance, with a degree of accuracy sufficient for the views of
the agriculturist, remain unimpeached.

The most valuable, and more strictly original part of this lecture,
is his statement of the quantity of soluble or nutritive matters
contained in varieties of the different substances that are used
as articles of food, either for man or cattle, and which he has
displayed in a tabular form.

The analyses were his own, and were conducted with a view to a
knowledge of the general nature and quantity of the products,
rather than to that of their intimate chemical composition.
He proceeded upon the assumption, that the excellence of
the different articles, as food, will be in a great measure
proportional to the quantities of soluble matter they afford;
although he admits that these quantities cannot be regarded
as _absolutely_ denoting their value. Albuminous or glutinous
matters have the characters of animal substances; sugar is more,
and extractive matter less nourishing than any other principles
composed of carbon, hydrogen, and oxygen. Certain combinations
likewise of these substances may be more nutritive than others.
There are some principles also, which, although soluble in the
vessels of the chemist, pass through the alimentary canal of
animals without change; such is _tannin_: on the other hand, there
are bodies which, although sparingly soluble in water, are readily
acted upon by the gastric juice; _gluten_ is a principle of this
description.

Shortly after Dr. Wollaston published his scale of chemical
equivalents, it occurred to me that by applying the sliding rule
to a series of nutritive substances, arranged according to the
analyses of Davy, some curious and important problems[106] might be
solved; or at least, that the accuracy of the conclusions might be
thus conveniently submitted to the test of practice. I accordingly
superintended the construction of such an instrument, and submitted
it to Davy, who expressed his approbation of the principle, but
doubted how far the accuracy of his analyses would justify the
experiment.

  [106] For example:--What weight of wheat is equivalent to a given
  weight of oats, barley, rye, &c.? Suppose three hundred pounds of
  potatoes feed twenty head of cattle for any given time, how many
  will the same weight of oats feed?

To such a scheme, however, I soon found that there existed a much
more serious objection. The operation of the insoluble matter
had been wholly neglected; and whatever views the chemist may
entertain, the experience of the physiologist has established,
beyond doubt, the influence of such matter in the process of
digestion. The capacity of the alimentary organs of graminivorous
animals sufficiently proves that they were designed for the
reception of a _large bulk_ of food, and not for provender in which
the nutritive matter is concentrated; and since the gramineous and
leguminous vegetables do not present this matter in a separate
state, and the animal is not furnished with an apparatus by which
he can remove it, the obvious inference is, that he was designed
to feed indiscriminately upon the whole; and that, unless bulk be
taken into the account, no fair inference can be deduced as to the
nutritive value of different vegetables.

Notwithstanding the difficulties which prevent our arriving at any
thing like an accurate conclusion upon so complicated a subject,
the results may be received as affording some general views with
regard to the comparative value of different nutritive vegetables.
It would thus appear that at least a fourth part of the weight of
the potatoe consists of nutritive matter, which is principally
starch;--that wheat consists of as much as ninety-five, barley of
ninety-two, oats of seventy-five, rye of eighty, and peas and beans
of about fifty-seven per cent. of nutritive matter.

The FOURTH LECTURE comprises subjects of the utmost importance,
and must be considered as constituting by far the most original
and valuable division of the work. It treats of soils,--their
constituent parts, their chemical analysis, their uses, their
improvement, and of the rocks and strata found beneath their
surface.

In the execution of this part of his labours, he has not only
improved on the processes of Fordyce and Kirwan, but he has
enriched the subject with much interesting and novel research.

"Soils, although extremely diversified in appearance and quality,
consist of comparatively few elements, which are in various states
of chemical combination, or of mechanical mixture.

"These substances are silica, lime, alumina, magnesia, the oxides
of iron, and of manganese; animal and vegetable matters in a
state of decomposition; together with certain saline bodies,
such as common salt, sulphate of magnesia, sometimes sulphate of
iron, nitrates of lime and magnesia, sulphate of potash, and the
carbonates of potash and soda.

"The silica in soils is usually combined with alumina and oxide of
iron; or with alumina, lime, magnesia, and oxide of iron, forming
gravel and sand of different degrees of fineness. The carbonate of
lime is usually in an impalpable form; but sometimes in the state
of calcareous sand. The magnesia, if not combined in the gravel
and sand of the soil, is in a fine powder united to carbonic acid.
The impalpable part of the soil, which is commonly called clay or
loam, consists of silica, alumina, lime, and magnesia; and is, in
fact, visually of the same composition as the hard sand, but more
finely divided. The vegetable, or animal matters (and the first
is by far the most common in soils,) exist in different states
of decomposition. They are sometimes fibrous, sometimes entirely
broken down and mixed with the soil.

"To form a just idea of soils, it is necessary to conceive
different rocks decomposed, or ground into parts and powder
of different degrees of fineness; some of their soluble parts
dissolved by water, and that water adhering to the mass, and the
whole mixed with larger or smaller quantities of the remains of
vegetables and animals, in different stages of decay."

Soils, then, would appear to have been originally produced from
the disintegration of rocks and strata; and hence there must be
at least as many varieties of them, as there are species of rocks
exposed at the surface of the earth; and they may be distinguished
by names derived from the rocks from which they were formed. Thus,
if a fine red earth be found immediately above decomposing basalt,
it may be denominated _basaltic_ soil. If fragments of quartz and
mica be found abundant, it may be denominated _granitic_ soil; and
the same principles may be extended to other analogous cases.

A general knowledge then of geology becomes essential to the
scientific agriculturist, not only to enable him to form a correct
judgment with respect to the connection between the varieties of
soil and the subjacent rocks, but to direct him to the different
mineral substances which may be associated together in their
vicinity, and which may contain principles capable of extending
their fertility, or of correcting the circumstances upon which
their poverty or barrenness may depend.

With this conviction, Davy proceeds to offer a general view of the
nature and position of rocks and strata in nature; but which, I
confess, appears to me to be wholly useless to those who have any
acquaintance with the subject, and far too meagre to convey any
instruction to those who have not made this branch of science an
object of study.

Upon this view, however, he has grounded a number of valuable
remarks; although his observations appear to have been too limited
to enable him to do justice to a subject of such extent and
importance. Had he fulfilled his intention of making a survey of
the county of Cornwall, the science must have been greatly advanced
by his labours, for there is no district in Great Britain so rich
in fact, and so capable of elucidating the history of soil, and
the advantages of cultivation, when conducted on the principles of
chemical philosophy. The soils superincumbent upon the different
rocks are distinct and characteristic; and even in the same
species varieties may be observed, in consequence of geological
peculiarities. I have, for instance, found that the fertility of
a granitic soil is increased by the abundance of felspar in the
parent rock;--that of a slaty soil by the degree of inclination or
dip of the strata: but the most extraordinary circumstance perhaps
connected with this subject, is the very remarkable fertility of
the land which lies over the junction of these rocks,--so obvious
indeed is it, that the eye alone is sufficient to trace it.

We are indebted to the author, in this lecture, for some very
ingenious and important remarks on the relations of different soils
to heat and moisture, and for a series of experiments by which his
views are supported.

Some soils, he observes, are more easily heated and more easily
cooled than others: for example, those that consist principally of
a stiff white clay are heated with difficulty; and being usually
very moist, they retain their heat only for a short time. _Chalks_
also are difficultly heated; but being dryer, they retain their
heat longer, less being consumed in the process of evaporation.

A black soil, and those that contain much carbonaceous or
ferruginous matter, acquire a higher temperature by exposure to the
sun, than pale-coloured soils.

When soils are perfectly dry, those that most readily become
heated, most rapidly cool; but the darkest-coloured dry soil,
abounding in animal and vegetable matters, cools more slowly than a
wet pale soil, composed entirely of earthy matter.

These results Davy gained by experiments made on different kinds of
soils, exposed for a given time to the sun, and in the shade; the
degrees of heating and cooling having been accurately ascertained
by the thermometer.

Nothing can be more evident, than that the genial heat of the soil,
particularly in spring, must be of the highest importance to the
rising plant. And when the leaves are fully developed, the ground
is shaded, and any injurious influence, which in the summer might
be expected from too great a heat, entirely prevented; so that
the temperature of the surface, when bare and exposed to the rays
of the sun, affords at least one indication of the degree of its
fertility; and the thermometer may therefore be sometimes a useful
instrument to the purchaser or improver of lands.

Water is said to exist in soils, either in a state of chemical
combination, or of cohesive attraction. It is in the latter state
only that it can be absorbed by the roots of plants, unless in
the case of the decomposition of animal and vegetable substances.
The more divided the parts of the soil are, the greater is its
attractive power for water; and the addition of vegetable and
animal matters still farther increases this power.

The quality of soils to absorb water from air, is much connected
with fertility. Davy informs us that he has compared this absorbent
power in numerous instances, and that he always found it greatest
in the most productive lands: he states, however, the important
fact, that those soils, such for instance as stiff clays, which
take up the greatest quantity of water, when it is poured upon
them in a fluid form, are not such as absorb most moisture from
the atmosphere in dry weather. They cake, and present only a small
surface to the air, and the vegetation on them is generally burnt
up almost as readily as on sands.

There is probably no district in which the importance of moisture
in relation to fertility is more apparent than in Cornwall; and
there is a provincial saying, that the land will bear a shower
every weekday, and two upon a Sunday: indeed, of such importance is
moisture, that it is by no means an uncommon practice to encourage
the growth of weeds, in order to diminish the evaporation; a
necessity which arises from the excess of siliceous matter in the
soil.

To those who are disposed to prosecute this enquiry, I should
recommend a perusal of Mr. Leslie's treatise on the "Relations of
Air to Heat and Moisture."

I must not quit the consideration of this lecture, without
adverting to the directions with which its author has furnished the
philosophical farmer for analysing the different varieties of soil;
and which are so clear, so perfect, and above all so simple, that
they are now introduced into all elementary works on chemistry,
as the only guide to such researches. His method for ascertaining
the quantity of carbonate of lime in any specimen, consists in
determining the loss of weight which takes place on its admixture
with muriatic acid; for since carbonate of lime, in all its states,
contains a determinate proportion of carbonic acid, it is evident
that, by estimating the quantity of elastic matter given out, the
proportion of carbonate of lime will be known. For conducting this
experiment, he contrived a very simple and ingenious piece of
pneumatic apparatus, in which the bulk of the carbonic acid is at
once measured by the quantity of water it displaces.

In his FIFTH LECTURE he enters upon the nature of the atmosphere,
and its influence on vegetables: he also examines the process of
the germination of seeds, and the functions of plants in their
different stages of growth; and concludes with a general view of
the progress of vegetation.

I shall merely mention a few of the more interesting points in this
enquiry.

In illustrating the importance of water to the vegetable creation,
he observes that the atmosphere always contains water in its
elastic and invisible form, the quantity of which will vary with
the temperature. In proportion as the weather is hotter, the
quantity is greater; and it is its condensation by diminution of
temperature, which gives rise to the phenomena of dew and mist.
The leaves of living plants appear to act upon this vapour, and
to absorb it. Some vegetables increase in weight from this cause,
when suspended in the atmosphere, and unconnected with the soil;
such are the house-leek, and different species of the aloe. In very
intense heats, and when the soil is dry, the life of plants seems
to be preserved by the absorbent powers of their leaves; and it is
a beautiful circumstance in the economy of Nature, that aqueous
vapour is most abundant in the atmosphere when it is most needed
for the purposes of life; and that when other sources of its supply
are cut off, this is most copious.[107]

  [107] The history of his native county would have furnished
  him with a parallel instance of the intelligence and design
  which Nature displays in connecting the wants and necessities
  of the different parts of creation, with the power and means
  of supplying them. In a primitive country like Cornwall, the
  siliceous soil necessarily requires much moisture, and we may
  perceive that the cause which occasions, at the same time
  supplies this want; for the rocks elevated above the surface,
  solicit a tribute from every passing cloud; while in alluvial
  and flat districts, where the soil is rich, deep, and retentive
  of moisture, the clouds float undisturbed over the plains, and
  the country frequently enjoys that uninterrupted series of dry
  weather which is so necessary to its fertility. Linnæus observes,
  that the plants which chiefly grow upon the summit of mountains,
  are rarely found in any other situation, except in marshes,
  because the clouds arrested in their progress by such elevations,
  keep the air in a state of perpetual moisture.

If water in its elastic and fluid states be essentially necessary
to the economy of vegetation, so even in its solid form, it is not
without its uses. Snow and ice are bad conductors of heat; and at
a period when the severity of the winter threatens the extinction
of vegetable life, Nature kindly throws her snowy mantle over the
surface; while in early spring the solution of the snow becomes the
first nourishment of the plant; at the same time, the expansion of
water in the act of congelation, and the subsequent contraction of
its bulk during a thaw, tend to pulverise the soil, to separate
its parts from each other, and, by making it more permeable to the
influence of the air, to prepare it for the offices it is destined
to perform.

He next proceeds to consider the action of the atmosphere on
plants, and to connect it with a general view of the progress
of vegetation. He commences with examining its relations to
germination.

"If a healthy seed be moistened and exposed to air at a temperature
not below 45°, it soon germinates; it shoots forth a _plume_ which
rises upwards, and a _radicle_ which descends.

"If the air be confined, it is found that, in the process of
germination, the oxygen, or a part of it, is absorbed. The azote
remains unaltered; no carbonic acid is taken away from the air; on
the contrary, some is added." Upon this point, critics have been
disposed to break a lance with Sir Humphry.

The doctrine, let it be observed, is at variance with the numerous
experiments made on this subject by Scheele, Cruickshank, and De
Saussure; the results of which agree in proving, that if seeds be
confined and made to germinate in a given portion of air, not a
_part_ only, but the _whole_ of the oxygen is consumed; and that
its place is supplied, not merely by _some_, but by an _equal bulk_
of carbonic acid.

Objections have been also started to his theory of the chemical
changes which the seed undergoes during the process of germination:
but were I to enter upon these discussions, time and space would
alike fail me, to say nothing of the patience of the reader, which
would be exhausted long before we could arrive at any satisfactory
conclusion. I shall for the same reasons pass over his observations
upon the influence exerted upon growing plants on the air: the
subject is involved in much difficulty, which can be only removed
by fresh experiments; nor, after all, is the great question,
whether the purity of the atmosphere is maintained by vegetation,
of any practical moment,--it is one which partakes more of
curiosity than of use, and might therefore have been well dispensed
with in a system of agriculture.

He agrees with many other philosophers in considering "the process
of malting as merely one in which germination is artificially
produced, and in which the starch is changed into sugar, which
sugar is afterwards, by fermentation, converted into spirit.

"It is," he continues, "very evident from the chemical principles
of germination, that the process should be carried on no farther
than to produce the sprouting of the radicle, and should be
checked as soon as this has made its distinct appearance. If it is
pushed to such a degree as to occasion the perfect developement of
the radicle and the plume, a considerable quantity of saccharine
matter will have been consumed in producing their expansion, and
there will be less spirit formed in fermentation, or produced in
distillation.

"As this circumstance is of some importance, I made, in October
1806, an experiment relating to it. I ascertained by the action of
alcohol, the relative proportions of saccharine matter in two equal
quantities of the same barley; in one of which the germination had
proceeded so far as to occasion protrusion of the radicle to nearly
a quarter of an inch beyond the grain in most of the specimens, and
in the other of which it had been checked before the radicle was a
line in length; the quantity of sugar afforded by the last was to
that in the first nearly as six to five."

The whole of this subject appears to be debateable ground between
the physiologists and chemists: the one considering the change
of starch into sugar as the result of the vital action of the
seed; the other affirming that the growth of the germ is in no
way necessary to the result, and is to be considered as a mere
indication of the due degree of change being effected in the
organic matter, or, in other words, that when the organized parts
exhibit a certain degree of developement, then the inorganic matter
is most completely changed. All growth beyond this is injurious,
as leading to a consumption of the inorganic matter. All less than
this is not otherwise disadvantageous, than as an indication
that the inorganic matter is not duly changed. This change, it
is farther affirmed, so far from depending upon vegetable life,
can be wrought on the matter of the seed after it is even reduced
to powder, or is separated in the form of starch. At all events,
it must be admitted as a beautiful arrangement in nature, that
the same agents which urge on the developement of the organized
parts, should, at the same time, assist in preparing food for their
support.

From this subject Davy is very naturally led to the consideration
of the ravages inflicted upon the infant plant by insects;
the saccharine matter in the cotyledons at the time of their
change into seed-leaves, rendering them exceedingly liable to
such attacks. He appears to have bestowed much attention on the
turnip-fly, a colyopterous insect, which fixes itself upon the
seed-leaves of the turnip at the time that they are beginning to
perform their functions. He relates the several remedies which
have been proposed for this evil; and from letters which have been
put in my possession, addressed to Dr. Cartwright as early as the
year 1804, he appears to have been engaged with that gentleman in
experiments made by sprinkling the young plants with lime and urine.

After alluding to the parasitical plants of different species,
which attach themselves to trees and shrubs, feed on their juices,
destroy their health, and finally their life, for which, at
present, there does not exist any remedy, he thus concludes his
lecture:

"To enumerate all the animal destroyers, and tyrants of the
vegetable kingdom, would be to give a catalogue of the greater
number of the classes in Zoology. Every species of plant almost is
the peculiar resting-place, or dominion, of some insect tribe; and
from the locust, the caterpillar, and snail, to the minute aphis, a
wonderful variety of the inferior insects are nourished, and live
by their ravages upon the vegetable world.

"The Hessian fly, still more destructive to wheat than the one
which ravages the turnip plant, has in some seasons threatened the
United States with a famine. And the French government is at this
time[108] issuing decrees with a view to occasion the destruction
of the larvæ of the grasshopper.

  [108] January 1813.

"In general, wet weather is most favourable to the propagation of
mildew, funguses, rust, and the small parasitical vegetables; dry
weather, to the increase of the insect tribes. Nature, amidst all
her changes, is continually directing her resources towards the
production and multiplication of life; and in the wise and grand
economy of the whole system, even the agents that appear injurious
to the hopes, and destructive to the comforts of man, are in fact
ultimately connected with a more exalted state of his powers and
his condition. His industry is awakened, his activity kept alive,
even by the defects of climates and season. By the accidents which
interfere with his efforts, he is made to exert his talents, to
look farther into futurity, and to consider the vegetable kingdom,
not as a secure and unalterable inheritance spontaneously providing
for his wants, but as a doubtful and insecure possession, to be
preserved only by labour, and extended and perfected by ingenuity."

HIS SIXTH LECTURE treats of manures of animal and vegetable origin,
and of the general principles with respect to their uses and modes
of application.

It is evident that plants, by their growth, must gradually
exhaust the soil of its richer and more nutrient parts; and
these can be alone restored by the application of manures. It is
equally obvious, that if a soil be sterile from any defect in its
constitution, such a defect can be only remedied by artificial
additions. Hence the introduction of foreign matter into the earth,
for the purpose of accelerating vegetation, and of increasing
the produce of its crops, is a practice which has been pursued
since the earliest period of agriculture. Unfortunately, however,
the greatest ignorance has prevailed in all ages with regard to
the best modes of rendering such a resource available; and the
farmer, instead of enriching the soil, has too frequently given
his treasures to the winds. "It is quite lamentable," says an
intelligent writer,[109] "to survey a farm-yard in many parts of
the kingdom; to see the abundance of vegetable matter that is
trodden for months under-foot, over a surface of perhaps half an
acre of land, exposed to all the rains that fall, by which its more
soluble and richer parts are washed away, or perhaps carried down
to poison the water of some stagnant pool, which the unfortunate
cattle are afterwards compelled to drink. From the yard, the manure
is often carted to the field, at the time when the land is rendered
impenetrable by frost; or, if this operation be delayed to a less
unseasonable period, it is then frequently laid down in small
heaps, or sometimes spread over the surface, exposed for many days
to the sun, the winds, and the rain, as if with the direct design
of dissipating those more volatile parts which it ought to be the
farmer's first endeavour to preserve.

  [109] Edinburgh Review, vol. xxii. p. 270.

"Nothing can be so likely to remove ignorance so deplorable, and
prejudices so inveterate, as the diffusion of real knowledge
concerning the nature of manures, and their mode of action on
soils, and on the plants which grow in them."

Davy, fully sensible of the practical importance of the subject,
and impressed with the conviction that it was capable of being
materially elucidated by the recent discoveries of chemistry,
determined to put forth his strength, in order to bring this
department of agriculture under the dominion of science; and
upon this occasion our philosopher presents himself in the only
character in which he ever ought to appear--in that of an original
experimentalist.

His first step in the enquiry was to ascertain whether solid
substances can pass from the soil through the minute pores in
the fibres of the root. He tried an experiment by introducing a
growing plant of peppermint into water which held in suspension a
quantity of impalpably powdered charcoal: but after a fortnight,
upon cutting through different parts of the roots, no carbonaceous
matter could be discovered in them, nor were the smallest fibres
even blackened,--though this must have happened, had the charcoal
been absorbed in a solid form. If a substance so essential to
plants as carbonaceous matter cannot be introduced except in a
state of solution into their organs, he very justly concludes that
other less essential bodies must be in the same case.

He also proved by experiment that solutions of sugar, mucilage,
jelly, and other principles, unless considerably diluted, clogged
up the vegetable organs with solid matter, and prevented the
transpiration by the leaves: when, however, this precaution was
taken, the plants grew most luxuriantly in such liquids.

He next proceeded to determine whether soluble vegetable substances
passed in an unchanged state into the roots of plants, by comparing
the products of the analysis of the roots of plants of mint which
had grown, some in common water, some in a solution of sugar:
the results favoured the opinion that they were so absorbed. It
appeared, moreover, that substances even poisonous to vegetables
did not offer an objection to this law. He introduced the roots of
a primrose into a weak solution of oxide of iron in vinegar, and
suffered them to remain in it till the leaves became yellow; the
roots were then carefully washed in distilled water, bruised, and
boiled in a small quantity of the same fluid: the decoction of them
passed through a filtre was examined, and found to contain iron; so
that this metal must have been taken up by the vessels or pores in
the root.

If to these facts are added those connected with the changes
which animal and vegetable substances undergo by the process of
putrefaction, we have all the data necessary for forming a rational
theory, to guide us in the management and application of manures.

Davy has very satisfactorily shown the cases in which putrefaction
or fermentation should be encouraged, and avoided. As a general
rule, it may be stated, that when manure consists principally of
matter soluble in water, its fermentation or putrefaction should
be prevented as much as possible; but on the contrary, when it
contains a large proportion of vegetable or animal fibre, such
processes become necessary.

To prevent manures from decomposing, he recommends that they should
be preserved dry, defended from the contact of the air, and kept
as cool as possible. Salt and alcohol, he observes, appear to owe
their powers of preserving animal and vegetable substances to their
attraction for water, by which they prevent its decomposing action,
and likewise to their excluding air. The importance of this latter
circumstance he illustrates by the success of M. Appart's method of
preserving meat.

By allowing the fermentation of manure to proceed beneath the soil,
rather than in the farm-yard, we not only preserve elements which
would otherwise be dissipated, but we obtain several incidental
advantages; for example, the production of _heat_, which is useful
in promoting the germination of the seed. This must be particularly
favourable to the wheat crop, in preserving a genial temperature
beneath the surface late in autumn, and during winter.

Again:--it is a general principle in chemistry, that in all
cases of decomposition, substances combine much more readily
at the moment of their disengagement, than after they have been
perfectly formed. And in fermentation beneath the soil, the fluid
matter produced is applied instantly, even whilst it is warm, to
the organs of the plant, and consequently is more likely to be
efficient than in manure that has gone through the process, and of
which all the principles have already entered into new combinations.

He examines with much attention the various animal and vegetable
matters which have been used as manure, and furnishes the farmer
with a number of practical remarks on their nature and mode of
operation. For these, the reader must refer to the work itself;
for my limits will not allow me to enter into the consideration of
_rape-cake_--_malt-dust_--_linseed-cake_--_sea-weeds_--_peat_
--_wood-ashes_--_fish_--_bones_--_hair_,_woollen rags_, _and
feathers_--_blood_, &c. &c.; to each of which he assigns peculiar
qualities and virtues.

As he regards the due regulation of the fermentative process of
the utmost importance, he has furnished some valuable hints for
the conduct of the farmer upon this occasion. He considers that
a compact marle, or a tenacious clay, offers the best protection
against the air; and before the dung is covered over, or, as it
were, sealed up, he recommends that it should be dried as much
as possible. If at any time it should heat strongly, he advises
the farmer to turn it over, and thus cool it by exposure to the
air; for the practice sometimes adopted of watering dunghills is
inconsistent with just chemical views. It may cool the dung for a
short time; but moisture, it will be remembered, is a principal
agent in all processes of decomposition.

In cases of the fermentation of dung, there are simple tests by
which the rapidity of the process, and consequently the injury
done, may be discovered. If, for instance, a thermometer plunged
into the mass does not rise above 100°, it may be concluded that
there is not much danger of the escape of aëriform matter; but
should it exceed this, the dung ought to be immediately spread
abroad.

When a piece of paper moistened in muriatic acid, held over the
steams arising from a dunghill, gives dense fumes, it is a certain
test that the decomposition is going too far; for this indicates
that volatile alkali is disengaged.

It may be truly said that, under the hand of Davy, the coldest
realities blossomed into poetry: the concluding passage of this
lecture certainly sanctions such an opinion, and is highly
characteristic of that peculiar genius to which I have before
alluded.[110] A subject less calculated than a heap of manure to
call forth a glowing sentiment, can scarcely be imagined.

  [110] Page 191.

"The doctrine," says he, "of the proper application of manures from
organized substances, offers an illustration of an important part
of the economy of nature, and of the happy order in which it is
arranged. The death and decay of animal substances tend to resolve
organized forms into chemical constituents; and the pernicious
effluvia disengaged in the process seem to point out the propriety
of burying them in the soil, where they are fitted to become the
food of vegetables. The fermentation and putrefaction of organized
substances in the free atmosphere are noxious processes; beneath
the surface of the ground they are salutary operations. In this
case the food of plants is prepared where it can be used; and that
which would offend the senses, and injure the health, if exposed,
is converted by gradual processes into forms of beauty and of
usefulness; the fetid gas is rendered a constituent of the aroma of
the flower, and what might be poison, becomes nourishment to man
and animals."

The SEVENTH LECTURE is devoted to the investigation of manures of
a mineral origin. He commences the subject by refuting the opinion
of Schrader and Braconnot, that the different earthy and saline
substances found in plants arise from new arrangements of the
elements of air and water, by the agencies of their living organs.

In 1801, he made an experiment on the growth of oats, supplied with
a limited quantity of distilled water, in a soil composed of pure
carbonate of lime. The soil and the water were placed in a vessel
of iron, which was included in a large jar, connected with the free
atmosphere by a tube, so curved as to prevent the possibility of
any dust, or fluid, or solid matter, from entering into the jar.
His object was to ascertain whether any siliceous earth would be
formed in the process of vegetation; but the oats grew very feebly,
and began to be yellow before any flowers formed. The entire
plants were burnt, and their ashes compared with those from an
equal number of grains of oat. Less siliceous earth was given by
the plants than by the grains; but their ashes yielded much more
carbonate of lime.

Numerous other authorities might be quoted to the same effect.
Jacquin states that the ashes of Glasswort (_Salsola-Soda_) when
it grows in inland situations, afford the vegetable alkali; but
when on the sea-shore, the fossile or mineral alkali. Du Hamel also
found, that plants which usually grow on the sea-shore, made small
progress when planted in soils containing little common salt. The
Sunflower, when growing on lands not containing nitre, does not
afford that substance; though when watered by its solution, it
yields nitre abundantly. De Saussure made plants grow in solutions
of different salts; and he ascertained that, in all cases, certain
portions of the salts were absorbed by the plant, and found
unaltered in their organs.

It may be admitted then as established, that the mineral principles
found in plants are derived from the soils in which they vegetate.
This fact becomes the foundation of the theory respecting the
operation of mineral manure.

Davy observes, that "the only substances which can with propriety
be called fossile manures, and which are found unmixed with the
remains of any organized beings, are certain alkaline earths, or
alkalies, and their combinations." If he intends to limit the term
to those bodies only which find their way into the structure of
plants, his definition may be correct; but I am inclined to take a
much wider view of the subject, and to include all those mineral
substances which promote vegetation by modifying the texture of the
soil:--but of this hereafter.

Lime, not only from its importance, but from the controversies
which it has occasioned, ranks first in the list of mineral manures.

That disputes concerning the uses of lime and its carbonate,
should have long existed, and be still continued amongst a class
of persons who, whatever may be their practical knowledge, are
not acquainted with the composition of the substances about
which they differ, is certainly by no means extraordinary. Davy,
therefore, very properly introduces the subject, by a description
of the nature and qualities of these bodies, and by marking the
distinctions between quicklime and its carbonate.

The substance commonly known by the name of _Limestone_ is a
compound of lime and carbonic acid, associated generally with
other earthy bodies, the nature and proportions of which vary in
different species. "When a limestone does not copiously effervesce
in acids, and is sufficiently hard to scratch glass, it contains
siliceous, and probably aluminous earth. When it is deep brown or
red, or strongly coloured of any of the shades of brown or yellow,
it contains oxide of iron; when it is not sufficiently hard to
scratch glass, but effervesces slowly, and makes the dilute nitric
acid in which it effervesces milky, it contains magnesia; and when
it is black, and emits a fetid smell if rubbed, it contains coally
or bituminous matter."

As the agricultural value of limestone is materially modified
by the substances with which it may be associated, their
analysis becomes an object of much importance, and the author has
accordingly proposed a simple method of effecting it.

Before any opinion can be formed of the manner in which these
different ingredients operate, it is necessary that the action
of the pure calcareous element as a manure should be thoroughly
understood.

In its caustic state, whether used in powder, or dissolved in
water, lime is injurious to plants. Davy informs us that he has, in
several instances, killed grass by watering it with lime water; but
in its combination with carbonic acid, it is an useful ingredient
in soils.

When newly-burnt lime is exposed to the atmosphere, it soon falls
into powder, from uniting with the moisture of the air; and the
same effect is immediately produced by throwing water upon it, when
it heats violently, and the water disappears: in this state it is
commonly called _slacked_ lime: chemists have named it the _hydrat_
of lime; and when this hydrat becomes a carbonate, by long exposure
to the air, its water is in part expelled, and the carbonic acid
takes its place.

Lime, whether freshly burnt, or slacked, acts powerfully on moist
fibrous vegetable matters, and forms with them a compost, of which
a part is usually soluble in water. By this operation, it renders
inert vegetable matter active; and as charcoal and oxygen (the
elements of carbonic acid) abound in vegetables, it is itself, at
the same time, converted into a carbonate. But limestone simply
powdered, marls, or chalks, do not thus act on vegetable matter;
and hence the operation of quicklime and mild lime depends on
principles altogether different. Quicklime acts on any hard
vegetable matter, so as to render it more readily soluble; the mild
limes, or carbonates, act only by improving the texture of the
soil, or by supplying a due proportion of calcareous matter: thus
almost all soils which do not effervesce with acids, are improved
by mild lime and sand, more than clays. I apprehend that it is upon
this principle the application of shelly sand proves beneficial in
Cornwall, although I have ascertained that, on some occasions, its
value depends upon its chemical action upon mineral bodies in the
soil.

Soils abounding in soluble vegetable manures are injured by
quicklime, as it tends to decompose their soluble matters, or to
form with them compounds less soluble than the pure vegetable
substance. With animal manures, it is equally exceptionable, unless
indeed they be too rich, or it becomes necessary to prevent noxious
effluvia: for since it decomposes them, it destroys their efficacy,
and tends to render the extractive matter insoluble.

The limestones containing alumina and silex are less fitted for
the purposes of manure than pure limestones; but the lime formed
from them has no noxious quality. Such stones are less efficacious,
merely because they furnish a smaller quantity of quicklime. Those,
however, that contain magnesia, if indiscreetly used, may be very
detrimental.

It had been long known to farmers in the neighbourhood of
Doncaster, that lime made from a certain limestone, when applied
to the land, often injured the crops considerably. Mr. Tennant
discovered that this limestone contained magnesia; and on mixing
some calcined magnesia with soil, in which he sowed different
seeds, he found that they either died, or very imperfectly
vegetated; and with great justice and ingenuity, he referred the
bad effects of the peculiar limestone to the magnesian earth it
contained. In prosecuting the enquiry, Davy however ascertained
that there were cases in which this magnesian lime was used with
good effect,--in small quantities, for example, on rich land: and
during his chemical consideration of the question, he was led to
the following satisfactory solution.

"Magnesia has a much weaker attraction for carbonic acid than lime,
and will remain in the state of caustic or calcined magnesia for
many months, though exposed to the air; and as long as any caustic
lime remains, the magnesia cannot be combined with carbonic acid,
for lime instantly attracts carbonic acid from magnesia. When
therefore a magnesian limestone is burnt, the magnesia is deprived
of its carbonic acid much sooner than the lime, and in this state
it is a poison to plants. That more magnesian lime may be used
upon rich soils,[111] seems to be owing to the circumstance, that
the decomposition of the manure in them supplies carbonic acid,
and thus converts it into a mild carbonate. Besides being used
in the forms of lime and carbonate of lime, calcareous matter is
applied for the purposes of agriculture in other combinations.
The principal body of this kind is _gypsum,_ or sulphate of lime;
respecting the uses and operation of which very discordant opinions
have been formed."

  [111] These facts have been confirmed by agriculturists, who
  could not possibly have had any favourite theory to support. Dr.
  Fenwick tells us, (Essays on Calcareous Manures, p. 11. 1798,)
  that in the county of Durham, the farmers always distinguish
  between _hot_ and _mild_ limes. They never apply the former
  to exhausted lands, or to any soil that has been long under a
  course of tillage, unless it be very deep and rich. In peaty
  soils, and in new, sour, and wild lands, the _hot_ limes, on
  the contrary, are preferred to the _mild_ ones. Dr. Fenwick
  made some experiments to ascertain the cause of the differences
  between these varieties of lime; and though he failed to discover
  that by analysis which Mr. Tennant subsequently ascertained, he
  nevertheless arrived at a just conclusion by simple observation;
  and was led to believe, that "what farmers term _hot_ limes, are
  such as re-absorb their fixed air more slowly, and therefore
  continue longer to exert the peculiar action of quicklime."

Its beneficial operation has been referred to two causes, viz. to
its power of attracting moisture from the air, or to its assisting
the putrefaction of animal substances; but Davy has shown by
experiments that neither of these theories can be supported by
facts.

The most extraordinary circumstance perhaps connected with the
history of this mineral manure, is the very opposite opinions which
have been formed respecting its value. In this country, although
there are various testimonies in its favour, it has never been
employed with the signal success which marked its adoption in
America, and which was so palpable and extraordinary as at once to
have ensured its universal introduction.

I was some years since assured by Mr. Maclure of Philadelphia, that
whenever any doubt or hesitation betrayed itself with respect to
its fertilizing agency, it was only necessary to sprinkle a small
quantity in a meadow, to satisfy the most sceptical; and that this
was usually done in the form of letters or characters, which in
a short time became so much more luxuriant than the surrounding
grass, as to be visible at a considerable distance. It is, I
understand, chiefly applied to grass lands as a _top-dressing_; and
the American farmers[112] explain its operation upon its solubility
in water, and its consequent absorption by the roots of the grass.
Davy, in examining the ashes of sainfoin, clover, and rye-grass,
which had grown in soils manured by gypsum, found considerable
quantities of that substance; and he thinks it probable that it
was intimately connected with their woody fibre. He attempts to
explain the reason why the application of gypsum is not generally
efficacious, by supposing that most of the cultivated soils may
already contain it in sufficient quantities for the use of the
grasses. I strongly suspect, however, that it will be hereafter
discovered to depend upon the nature of the soil in its hygrometric
relations. From the facts already recorded, it would appear that
it never answers near the sea, nor in wet lands. In consequence of
its solubility, it is enabled to penetrate and pervade the whole
vegetable structure; and the experiments of Davy have proved its
presence in the ashes of plants exposed to its operation, and have
rendered it probable that it enters into union with their woody
fibre, by which the density of their textures will be increased,
and consequently the evaporation from their leaves diminished; I
am from such considerations induced to think that gypsum does not
act by effecting any chemical change in the soil, but solely by
diminishing the plants evaporation. This idea seems to be borne out
by the evidence furnished by the different circumstances attending
the operation of this manure: we find, for example, that succulent
vegetables, planted on dry soils, are those which are principally
benefited by its application, and that the various grasses so
manured retain their verdure, even in the dryest season and on
the most arid lands; at the same time, we find that these crops,
especially clover, acquire a proportionate increase in the density
of their fibres, that is to say, that they become much more rank
and stubborn, and often to such a degree does this take place,
that in America, where its effects are best understood, sheep
not uncommonly refuse to feed upon them. Upon the same principle
we find that, under circumstances or in situations where the
evaporation of a plant is provided for by a constant supply of
moisture, the effects of gypsum cease to be apparent.

  [112] When this substance was first introduced into America,
  which is nearly forty years since, it was imported from the
  quarries of Montmartre, and in such request was it, that a bushel
  of wheat was usually given for the same measure of gypsum:
  it is now, I believe, obtained from Nova Scotia; I have not
  heard that it has been found within the States. It may perhaps
  serve to convey some idea of the extent to which it has been
  applied, when I state, that Mr. Maclure assured me that not
  less than three hundred vessels are constantly employed in the
  traffic, and that in Philadelphia twenty merchants, at least,
  are engaged in supplying the demand for it. Its efficacy appears
  to be considerably increased by applying it in a minute state
  of division; and a want of attention to this circumstance may
  possibly have been one of the causes which have rendered its
  advantages less conspicuous in England. In America, three or four
  hundred mills, of a peculiar construction, have been erected in
  different parts for the purpose of grinding it.

Davy hints at a process by which gypsum may be formed in a
soil containing sulphate of iron, by the action of calcareous
manure,[113] and which was first pointed out by Dr. Pearson. I can
confirm this statement by the results of experiments I formerly
made in Cornwall, where soil containing this salt of iron had been
manured by shelly sand.

  [113] Gypsum is readily produced by the admixture of decomposing
  pyrites and calcareous matter: in proof of which the Mineralogist
  can produce specimens of oyster shells studded with crystals of
  selenite from Shotover; and alum from the _aluminous shale_ at
  the Hurlet Mine near Glasgow.

In pursuing his enquiry into the efficacy of mineral manure, Davy
proceeds to investigate the efficacy of the fixed alkalies, and
observes that their general tendency is to give solubility to
vegetable matters, and in this way to render carbonaceous and other
substances capable of being taken up by the tubes in the radical
fibres of plants. The vegetable alkali has likewise a strong
attraction for water, and even in small quantities may tend to give
a due degree of moisture to the soil, or to other manures.

He considers that pure salt may act, like gypsum, phosphate of
lime, and the alkalies, by entering into the composition of the
plant. Upon the subject of salt, however, his remarks are very
meagre and unsatisfactory: at the time he composed his lecture, the
subject had not excited that public attention which the writings of
Mr. Parkes, Sir Thomas Bernard, and others, have since awakened.

Had our philosopher undertaken the agricultural survey of Cornwall,
his lecture on mineral manure must have been very considerably
extended. He would have learnt that various rocks reduced to
small fragments, are commonly applied as dressing; he would have
explained the cause of the fertility so generally associated with
hornblende rocks;--he would have speculated upon the influence
of iron in giving fruitfulness; and above all, he would have
taught the agriculturist the scientific use of calcareous sand, by
pointing out the description of lands which are most likely to be
benefited by its application.

The EIGHTH LECTURE concludes the subject of the chemistry of
Agriculture, by establishing the theory of the operation of burning
lands. He considers the process to be useful in rendering the soil
less compact, and less tenacious and retentive of moisture; and
that, when properly applied, it is capable of converting a matter
that was stiff, damp, and cold, into one powdery, dry, and warm,
and much more proper as a bed for vegetable life. He states the
great objection made by speculative chemists to paring and burning,
to be the unavoidable destruction of vegetable and animal matter,
or the manure of the soil; but he considers that, in those cases
in which the texture of its earthy ingredients is permanently
improved, there is more than a compensation for so temporary a
disadvantage; and that in some soils, where there is an excess of
inert vegetable matter, the destruction of it must be beneficial,
and that the carbonaceous matter remaining in the ashes may be
more useful to the crop than the vegetable fibre from which it was
produced.

In this view of the subject it is evident, that all poor siliceous
sands must be injured by the operation; "and here," says Davy,
"practice is found to accord with theory. Mr. Arthur Young, in his
Essay on Manures, states, 'that he found burning injure sand;'
and the operation is never performed by good agriculturists upon
siliceous sandy soils, after they have been once brought into
cultivation. An intelligent farmer in Mount's Bay told me, that
he had pared and burned a small field several years ago, which he
had not been able to bring again into good condition. I examined
the spot,--the grass was very poor and scanty, and the soil an
arid siliceous sand." _Irrigation_, or _watering land_, is a
practice, he observes, which at first view appears the reverse of
torrefaction; and, in general, the operation of water in nature is
to bring earthy substances into an extreme state of division. But
in the artificial watering of meadows, the beneficial effects may
depend upon many different causes, some chemical, some mechanical.
It may act as a simple supply of moisture to the roots, or it may
carry into the soil foreign matter, or diffuse that which exists in
it more equally through its substance.

He concludes with some valuable scientific observations upon
the process of _fallowing_, by which he attempts to correct
the prejudices which have existed with regard to its benefits.
He points out, on the other hand, the great advantages of the
convertible system of husbandry, by which the whole of the manure
is employed; and those parts of it which are not fitted for one
crop, remain as nourishment for another. These views he illustrates
by a reference to the course of crops adopted by Mr. Coke, in which
"the turnip is the first in the order of succession; and this crop
is manured with recent dung, which immediately affords sufficient
soluble matter for its nourishment; and the heat produced in
fermentation assists the germination of the seed and the growth
of the plant. After turnips, barley with grass seeds is sown; and
the land having been little exhausted by the turnip crop, affords
the soluble parts of the decomposing manure to the grain. The
grasses, rye-grass, and clover remain, which derive a small part
only of their organized matter from the soil, and probably consume
the gypsum in the manure which would be useless to other crops;
these plants likewise, by their large system of leaves, absorb a
considerable quantity of nourishment from the atmosphere; and when
ploughed in at the end of two years, the decay of their roots and
leaves affords manure for the wheat crop; and at this period of the
course, the woody fibre of the farm-yard manure, which contains
the phosphate of lime and the other difficultly soluble parts, is
broken down; and as soon as the most exhausting crop is taken,
recent manure is again supplied."

At the end of his system is added an Appendix, containing "An
Account of the results of Experiments on the produce and nutritive
qualities of the Grasses and other plants used as the food of
animals; instituted by John Duke of Bedford." But as these
experiments do not admit either of abridgement or analysis, the
reader must refer to the original source for information.

I shall conclude this long, and, I fear, somewhat tedious review,
with the animated appeal so earnestly addressed by the illustrious
author to the philosophical readers of his work.

"I trust that the enquiry will be pursued by others; and that in
proportion as chemical philosophy advances towards perfection, it
will afford new aids to agriculture: there are sufficient motives
connected both with pleasure and profit, to encourage ingenious
men to pursue this new path of investigation. Science cannot long
be despised by any persons as the mere speculation of theorists,
but must soon be considered by all ranks of men in its true point
of view, as the refinement of common sense guided by experience,
gradually substituting sound and rational principles for vague
popular prejudices.

"The soil offers inexhaustible resources, which, when properly
appreciated and employed, must increase our wealth, our population,
and our physical strength.

"We possess advantages in the use of machinery, and the division
of labour, belonging to no other nation. And the same energy
of character, the same extent of resources, which have always
distinguished the people of the British Islands, and made them
excel in arms, commerce, letters, and philosophy, apply with
the happiest effects to the improvement of the cultivation of
the earth. Nothing is impossible to labour, aided by ingenuity.
The true objects of the agriculturist are likewise those of the
patriot. Men value most what they have gained with effort; a just
confidence in their own powers results from success; they love
their country better, because they have seen it improved by their
own talents and industry; and they identify with their interests
the existence of those institutions which have afforded them
security, independence, and the multiplied enjoyments of civilized
life."

END OF THE FIRST VOLUME.

LONDON:

PRINTED BY SAMUEL BENTLEY,

Dorset Street, Fleet Street.

Transcriber's note:
    Minor spelling and punctuation inconsistencies, and hyphenated
    words,  have been harmonized. The formatting of the letters
    has been regularized. Every effort to decipher the hand written
    letter by Sir Humphry Davy has been made, however, there are no
    guarantees that it is correct.