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             Useful Knowledge: 4th ed. Minerals. Vol 1 of 3


[Illustration: Frontispiece to Vol. I. see Page 238, 239.
Comparative Height of Mountains, Cities and Lakes
British Islands –– Continent of Europe –– Islands not British –– Asia ––
America
J. Shury sculp.]


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                           USEFUL KNOWLEDGE:

                                   OR

                           A FAMILIAR ACCOUNT

                                 OF THE

                          VARIOUS PRODUCTIONS

                                   OF

                                Nature,

                    MINERAL, VEGETABLE, AND ANIMAL,

             WHICH ARE CHIEFLY EMPLOYED FOR THE USE OF MAN.

   Illustrated with numerous Figures, and intended as a Work both of
                       Instruction and Reference.

                                ───────

                                 BY THE

                     REV. WILLIAM BINGLEY, AM. FLS.

     LATE OF PETERHOUSE, CAMBRIDGE, AND AUTHOR OF ANIMAL BIOGRAPHY.

                    [Illustration: Publisher’s Logo]

                           IN THREE VOLUMES.

                           VOL. I. MINERALS.

                                ───────

                            FOURTH EDITION.

                                ───────

             LONDON: PRINTED FOR BALDWIN, CRADOCK, AND JOY;
                           HARVEY AND DARTON;
                        AND C. AND J. RIVINGTON.

                                ───────

                                 1825.


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             C. Baldwin, Printer,
          New Bridge─street, London.


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                                PREFACE.

                                ───────

THE mode in which instruction has hitherto been conveyed, on the
peculiar subjects of the present work, has chiefly been by small books,
in question and answer, denominated catechisms. But such, however
respectable in themselves, or however advantageous for children, are
wholly insufficient for persons who are in search of extended knowledge,
and desirous of furnishing their minds with useful information.

On these subjects there has not hitherto been published any work in
which they are collectively to be found; nor could a knowledge of them
be obtained but by the consultation of many and expensive writings. That
they are generally important to be known will not probably be denied.

It has consequently been the object of the author to compress all the
interesting information that could be obtained respecting them, within
as narrow a compass, and at the same time to render this information as
entertaining, and as devoid of technical words and phrases, as possible.

The scheme of the work will, it is hoped, be found sufficiently simple.
The passage in smaller characters at the head of each article, is in
general so arranged as to reply to the questions, “What is?” “What are?”
or “How do you know?” For instance: “What is flint?” (See Vol. I. p.
53.) The answer will be found thus: “Flint is a peculiarly hard and
compact kind of stone, generally of smoke─grey colour, passing into
greyish white, reddish, or brown. It is nearly thrice as heavy as water,
and, when broken, will split in every direction, into pieces which have
a smooth surface.” The author is aware that, in many instances, the
definitions are defective: but this has, in general, arisen from a
necessity of rendering them short, and at the same time of using such
terms as would be likely to convey information to the minds of persons
who have had no previous knowledge of the systems of natural history.

After the definition, a further illustration sometimes follows; and in
the large characters will be found a brief detail of the history and
uses of the object described. The articles are numbered, for the greater
convenience both of reference and explanation, but particularly the
latter. Thus, under the explanation of CARBON, it is stated that “in
combination with oxygen (21) it forms carbonic acid (26), and that it is
the chief component part of pit─coal (217), petroleum (213), and other
bituminous substances.” By a reference to the numbers inserted, each of
the words, against which they stand, will be explained: whilst at least
three of them would otherwise have been incomprehensible by the
generality of unscientific readers.

It must be remarked that the reader will not here find an account of
every production of nature, which is employed for the use of man, nor
even all the uses of such objects as are described. The most important
of the productions, and the principal of the uses, are all that he
trusts can reasonably be required in a work of the present extent. On
this ground it is that a great number of animals, which are in request
only for food, have been wholly omitted.

The figures that are inserted have been drawn upon as small and
economical a scale as was compatible with a sufficiently accurate
representation of the objects to which they relate. If the reader be
desirous of reference to further illustration, he will derive much
satisfaction from the invaluable figures of Mr. Sowerby in his British
and Exotic Mineralogy, and English Botany, and Woodville’s Medical
Botany; as well as from those in Dr. Shaw’s General Zoology, and
Bewick’s Histories of Quadrupeds and British Birds. There are also many
figures of useful animals in the author’s own work, entitled “Memoirs of
British Quadrupeds.”


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                             ADVERTISEMENT

                                 TO THE

                             THIRD EDITION.


Since this work was first printed, the author has made in it
considerable improvements. The first volume, particularly, contains many
additional articles, and more than half of it has been re─written. The
plates also have been re─engraved. For the plate of the mountains a new
drawing has been made, that the scale might be extended, and many
particulars might be introduced which before were omitted. For the
plates of vegetables every drawing has been corrected; and, in place of
such figures as were most defective, new ones have been inserted.

  Charlotte─street, Bloomsbury,
  London, 1st March, 1821.


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                       EXPLANATION OF THE PLATES

                                 OF THE

                             FIRST VOLUME.

                                ───────

                             FRONTISPIECE.

                  This is explained in pages 236, 237.


                                PLATE I.

              Fig.            MINERAL DEPOSITS.
                1. Horizontal beds or strata.
                   a. Veins or dykes.
                2. Bending strata.
                3. Minerals in detached masses.
                4. Disjoined strata.
                   b. A fault.




                               PLATE II.

                             CRYSTALS, &c.

                5. Octohedron.

                6. Rough diamond.

                7. Profile of a brilliant─cut stone.

                8. Profile of a rose─cut stone.

                9. Plane of a table─cut stone.

               10. Plane and profile of the Pitt diamond.

               11. Dodecahedron.

               12. Rough garnet.

               13. Six─sided pyramids, joined base to base.

                14 Regular four─sided prism.

               15. Six─sided prism.

               16. Cube.

               17. Four─sided pyramid having a rhomb for
                     its base.




                               PLATE III.

                           SECTION OF ROCKS.
                          I. Primitive Rocks.

              Fig.
                1. Granite.
                2. Gneiss.
                3. Mica─slate.
                4. Clay─slate.
                   a. Lime─stone.
                   b.  Quartz.
                5. Primitive lime─stone.


                         II.  Secondary Rocks.
                          1. Transition Rocks.

                6. Grey─wacka.
                7. Transition lime─stone.


                            2. Floetz Rocks.

                8. Old red sand─stone.

                9. Alternating strata of lime─stone and
                     sand─stone.


                        III. Alluvial Deposits.

               10. Alluvial strata of clay, gravel, &c.,
                     &c.




                                ───────

The BINDER is desired to insert all the Plates, except the
    Frontispieces, immediately after the Explanations in the respective
    Volumes.


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[Illustration: Pl. 1. Vol. I.
Sections of Strata &c.
J. Shury. sculp.]


[Illustration: Pl. 2. Vol. I.
CRYSTALS &c.]


[Illustration: Pl. 3. Vol. I.
Section of Rocks.
J Shury sculp.]


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                           USEFUL KNOWLEDGE.

                                ───────

                               MINERALS.

                                ───────

                            _INTRODUCTION._


1. MINERALS are natural bodies destitute of organization and life: and
MINERALOGY is that branch of natural science which treats of the
properties and relations of such bodies.


                           MINERAL DEPOSITS.

2. If we penetrate beneath the surface of the earth, we observe there a
very remarkable arrangement. Instead of a generally uniform appearance,
as we see on the surface, we pass through divers substances, as clay,
gravel, sand, and numerous others, deposited in _beds_ or _strata_ of
various thickness, from a few inches to a great many feet (Pl. I. Fig.
1). These lie, for the most part, nearly horizontal: but in some
instances, particularly in mountainous countries, they take different
degrees of inclination; and, in places where the country consists of
gently sloping hills and vales, the beds have a waving or bending form
(Pl. 1, Fig. 3). The strata of which the earth is composed, as deep as
the curiosity or the necessities of mankind have induced them to
explore, satisfactorily demonstrate the wisdom which has been displayed
in the arrangement of materials requisite for the use of men and
animals.

The first layer is frequently a rich, black mould, formed almost wholly
of animal and vegetable remains. This yields sustenance to the vegetable
productions; and thereby becomes the actual, though not the immediate,
support of the whole animal creation.—Beneath this is often found a
thick bed of clay, that furnishes to man a substance of which to make
bricks, tiles, various kinds of pottery, and innumerable other articles
for the comfort of social life.—Next are deposited vast beds of gravel,
that are of use in numerous points of view.—Underneath this are the
infinitely varying strata of sandstone, limestone, &c. which not only
serve for the construction of buildings, and for other important
purposes, but also frequently surround mines which contain the valuable
metals.—Beneath a slaty stratum are usually discovered those immense
beds of coal so requisite for the comfort, and, in some situations, even
for the existence of man.

These strata, it is true, are not always found together, nor are they
always discovered in the same order; but the statement will suffice to
show the general nature of their arrangement.

3. Minerals are sometimes observed in detached _masses_ of various size,
and situated at various depths in the earth (Pl. I, Fig. 1).

4. They are also found in a kind of natural clefts which cross the
regular mineral beds or strata in different directions (Pl. I, Fig. 1,
_a_, Pl. I, Fig. 4, _b_). When these contain metallic ores, they are
styled _veins_; but when they contain only stony or earthy matters, the
miners call them _dykes_. They vary much both in magnitude and length.
Six thousand feet are considered an unusual length for veins, though, in
some instances, veins have been traced upwards of four miles. Few veins
extend more than 1200 feet below the surface of the mountains in which
they are situated. They are usually much inclined; but they sometimes
descend in a direction parallel with the beds of rock in which they
occur.

5. At the places where dykes or veins pass through the earth, they
occasionally disjoint the strata in a very singular manner (Pl. I, Fig.
4). Some of the coal strata, for instance, are thrown down or raised on
one side of a dyke upwards of a hundred yards; and the miner, after
penetrating through this dyke, instead of finding the same coal again,
meets, on the opposite side, with beds of stone or clay. Hence he is
frequently at a loss how to proceed in searching for the coal of which
he is in pursuit; and hence it is that to such dykes the peculiar name
of _faults_ has sometimes been given.

6. In England the _metallic ores_ are generally found in veins, that
form a considerable angle with the regular strata. This in Cornwall is
uniformly the case. And it is remarkable, concerning the veins of tin
and copper of that county, that they run in a direction nearly east and
west; whilst the dykes, or veins of other substances, run for the most
part north and south.

7. The thickness of veins, and the quantity and quality of the ores they
contain, differ in every mine. Some are only a few inches wide, whilst
others extend to the width of several feet. The vein at Dalcooth mine,
in Cornwall, varies from two or three to forty feet and upwards; and, in
some parts, it contracts so as to be little more than six inches across.

8. In Cornwall the first traces of tin and copper are usually found at
the surface of the ground, and thence to the depth of 80 or 100 feet
beneath; and it is said that no miner has ever yet seen the bottom of a
vein, although several have been wrought to the depth of more than 1000
feet. The veins of these metals have, in some instances, been worked to
the length of three or four miles.

9. It is frequently observed that metallic veins are separated, from the
substances they intersect, by a thin wall, or lining, of minerals
different from these substances, and also by a layer of clay on each
side of the vein. It is also remarked that the same substance which
forms the outer coat of the vein is often intermixed with the ore, or
forms layers alternately with it. This has usually the denomination of
_matrix_ or _gangue_.

10. There are few mines of any considerable depth that would not be
flooded with _water_ from internal springs were not means adopted for
drawing off this fluid. The steam engines that are employed for this
purpose in some of the Cornish mines are so powerful as to discharge
incessantly, both by night and day, a quantity of water, equal to at
least 1000 gallons, or near twenty hogsheads, every minute.


                  SYSTEMATIC ARRANGEMENT OF MINERALS.

11. To a superficial observer, perhaps nothing would appear more easy
than to describe a mineral. This, however, is by no means the case. The
same general appearance sometimes prevails in substances that are very
different from each other; and the same stone, in its different states,
is often extremely varied in its appearance. To these difficulties it
must be added, that the combinations of mineral substances are
multiplied to a great extent. A little application, however,
particularly if the student be possessed of a collection of arranged and
named specimens, which he will have no difficulty in procuring at a
reasonable price, will enable him to overcome all the obstacles that
otherwise might impede his progress in beginning to acquire a knowledge
of this interesting science.[1]

12. The most simple and natural division of minerals is into four
classes, of, 1. STONES; 2. SALTS; 3. COMBUSTIBLES; and, 4. METALS; and
the following table, which has chiefly been arranged from the system of
Werner, the well─known German mineralogist, will exhibit a tolerably
correct outline of the classification of these substances. To reduce the
whole within the compass of a single page, many of the families,
however, have necessarily been omitted.

Footnote 1:

  Such collections are supplied by Mr. Mawe, No. 149, Strand, London.
  His terms, for collections containing from 100 to 200 specimens, are 5
  guineas; from 200 to 300 specimens, 10 guineas; and from 300 to 400
  specimens, 15 guineas. For collections containing from 350 to 400
  specimens, more select, and comprising a better suite of precious
  stones, he charges from 20 to 30 guineas; and for larger collections,
  from 50 to 100 guineas. At the particular request of the author, Mr.
  Mawe has arranged a few collections of minerals, and numbered them in
  such manner as to correspond with, and illustrate the present volume.


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                                                      PRINCIPAL SPECIES.
                                        { Diamond.     _Diamond_.
                                        {
                                        { Zircon.      _Jargoon_.
                                        {
                                        {            { _Oriental sapphire_.
                                        { Ruby.      { _Oriental ruby_.
                              { Scratch {            { _Emery_.
                              { glass. {
                              {         { Schorl.    { _Topaz_.
                              {         {            { _Emerald_.
                              {
                              {         { Garnet.      _Precious garnet_.
                              {
                              {         {            { _Crystal_.
                              {         { Quartz.    { _Flint_.
              { I.  EARTHY.   {         {            { _Agate_.
              {               {                      { _Opal_.
              {               {
              {               {          { Clay.       _Pure clay_.
              {               {          { Clay slate. _Roofing slate_.
              {               { Will not { Mica.       _Muscovy glass_.
              {               { scratch  { Soapstone.  _Fuller’s earth_.
  { I. STONES {               { glass.   {
  {           {                          { Talc.     { _Talc_.
  {           {                                      { _Asbestos_.
  {           {
  {           {                                      { _Limestone_.
  {           {                          { Lime.     { _Phosphat of lime_.
  {           {                          {           { _Fluor spar_.
  {           { II.  SALINE.             {           { _Alabaster_.
  {                                      {
  {                                      { Barytes.
  {                                      { Strontian.
  {
  {                                      { Alumine.    _Alum_.
  {                                      {
  {                                      { Magnesia.   _Epsom salt_.
  {                                      {
  { II. SALTS.                           { Soda.     { _Common salt_.
  {                                      {           { _Borax_.
  {                                      {
  {                                      { Potash.     _Nitre_.
  {                                      {
  {                                      { Ammonia.    _Sal─ammoniac_.
  {
  {                                      { Sulphur.    _Sulphur_.
  {                                      {
  {                                      {           { _Naphtha_.
  { III. COMBUSTIBLES                    { Bitumen.  { _Coal_.
  {                                      {           { _Jet_.
  {                                      {
  {                                      { Graphite.   _Black─lead_.
  {                                      {
  {                                      { Resin.      _Amber_.
  {
  {                                      { Platina.    _Platina_.
  {                                      { Gold.       _Gold_.
  {                                      { Mercury.    _Mercury_.
  {                                      { Silver.     _Silver_.
  {              { I. MALLEABLE.         { Copper.     _Copper_.
  {              {                       { Iron.       _Iron_.
  {              {                       { Tin.        _Tin_.
  {              {                       { Lead.       _Lead_.
  { IV. METALS.  {                       { Nickel.     _Nickel_.
                 {                       { Zinc.       _Zinc_.
                 {
                 {                       { Arsenic.    _Arsenic_.
                 {                       { Bismuth.    _Bismuth_.
                 { II. BRITTLE.          { Cobalt.     _Cobalt_.
                                         { Manganese.  _Manganese_.
                                         { &c. &c.


13.To complete a general view of the different productions of the
mineral kingdom, it is requisite to subjoin a tabular arrangement of the
various kinds of _rocks_.


                                                    SPECIES.
                                        { 1. Granite.
                                        { 2. Gneiss.
                                        { 3. Mica slate.
                                        { 4. Clay slate.
                                        { 5. Primitive limestone.
                                        { 6. Primitive trap.
                                        { 7. Serpentine.
 { I.  PRIMITIVE.                       { 8. Porphyry.
 {                                      { 9. Sienite.
 {                                      {10. Topaz rock.
 {                                      {11. Quartz rock.
 {                                      {12. Primitive flinty slate.
 {                                      {13. Primitive gypsum.
 {                                      {14. White stone.
 {
 {                                      { 1. Transition limestone.
 {                 { I. TRANSITION      { 2. Transition trap.
 {                 {      ROCKS.        { 3. Grey wacke.
 {                 {                    { 4. Transition flinty slate.
 {                 {                    { 5. Transition gypsum.
 {                 {
 { II.  SECONDARY. {                    { 1. Old red sandstone.
 {                 {                    { 2. Floetz limestone.
 {                 {                    { 3. Floetz gypsum.
 {                 {                    { 4. Second, or variegated sandstone.
 {                 {                    { 5. Second floetz gypsum.
 {                 { II. FLOETZ         { 6. Shell limestone.
 {                 {       ROCKS.       { 7. Third sandstone.
 {                                      { 8. Rock salt.
 {                                      { 9. Chalk.
 {                                      {10. Floetz trap.
 {                                      {11. Coal.
 {                                      {12. Newest floetz trap.
 {
 {                                      { 1. Peat.
 {                                      { 2. Sand and gravel.
 { III.  ALLUVIAL.                      { 3. Loam.
 {                                      { 4. Bog iron ore.
 {                                      { 5. Calcareous tufa, &c.
 {
 {                                      { 1. Burnt clay.
 {                 { I. PSEUDO VOLCANIC { 2. Porcelain jasper.
 {                 {      ROCKS.        { 3. Earth slag.
 {                 {                    { 4. Columnar clay ironstone.
 { IV.  VOLCANIC.  {                    { 5. Polishing slate.
                   {
                   { II. TRUE VOLCANIC  { 1. Stones and ashes.
                   {       ROCKS.       { 2. Lava.
                                        { 3. Matter of muddy eruptions.




14. For the purpose of ascertaining the names and characters of
minerals, attention must be paid to their _form_, _surface_, _lustre_,
_fracture_, or the appearance of their internal surface when broken;
_structure_, _transparence_, _streak_, or the mark left when scratched
by any hard body; _stain_, or trace left when rubbed upon paper;
_cohesion_, whether solid, friable, or fluid: _hardness_, or the
resistance which they oppose when scratched; _tenacity_, or the
resistance which they oppose to the stroke of a hammer; _flexibility_,
or their property of bending without breaking; _feel_, or the sensation
communicated by their surfaces when handled; _smell_, _taste_,
_adherence to the tongue_, _sound_, _specific gravity_, or weight in
comparison with that of water; _colour_ and _electricity_.

15. To ascertain the _chemical properties_ of minerals, one of the most
important instruments is the blow─pipe. This is a tube which terminates
in a cavity as fine as a small wire, and through which the air is
forced, and made to play upon the flame of a candle. The flame is thus
concentrated, and directed against small particles of the mineral to be
examined, which is placed upon a bit of charcoal in a spoon of platina
or silver. The air is forced into the blow─pipe by the mouth of the
person using it, or by bellows attached to it for that purpose. Under
this operation we have an opportunity of trying the action of other
bodies upon minerals at a very high temperature; and the properties
which these experiments bring into view enable us, in many cases, to
ascertain, not only the nature, but even the component parts, of
minerals.


                       SIMPLE MINERAL SUBSTANCES.

16. As a necessary introduction to the study of minerals, it is
requisite to describe, in a brief manner, such simple substances as form
their constituent parts. Few of these, it is true, are to be found in a
separate, uncombined state; yet that they do exist, and that they are to
be obtained from the minerals with which they are united, we have the
proof of every day’s experience.


                          UNCONFINABLE FLUIDS.

17. There are some kinds of unconfinable fluids, the existence even of
which is manifested only by their contact with other bodies, or becoming
separated from them. They are of a nature too subtile to be collected or
confined in our vessels for the purpose of examination, and the
investigation of their properties has consequently been attended with
peculiar difficulty. Those at present known are _caloric_, _light_,
_electricity_, and _magnetism_; but of these the first only is
immediately connected with the subjects of our present investigation.

18. _Caloric_.—Every one is acquainted with the different sensations of
heat and cold. That matter which produces on our bodies the sensation of
_heat_ has the name of _Caloric_; heat being only an effect, of which
caloric is the cause. This is extended in a greater or less degree
through the whole extent of space, and penetrates into the interior of
even the most solid bodies: in so doing it expands the particles of
which they are composed, augments their bulk, and diminishes their
solidity. The sun is the principal fountain from which the earth is
supplied with this fluid; and it passes thence to us at the rate of
12,000,000 of miles per minute. The defect of caloric in any substance
occasions the sensation called cold.

Were the world deprived of caloric, every species of organized being
would, from that moment, cease to exist. It is the cause of all
fluidity: to it every production of the earth has been most essentially
indebted, even for its form and structure; and in no respect do the
power and goodness of the Almighty appear more conspicuous than in the
creation, dispersion, and continuance, of this most subtile and
astonishing fluid.

19. All the various substances with which we are acquainted must be
considered either as solid or fluid. Every substance is defined to be a
_solid_ in which the parts are so united or connected that it requires
an external force to separate them. A _fluid_, on the contrary, is a
body the parts of which are so loosely connected that they not only
yield easily to any force impressed upon them, but also move freely
amongst each other; and every fluid is a combination of caloric with
some other substance.

20. Fluids are of two kinds: one of these, called _liquids_, have, when
at rest, a smooth and distinct surface, and are distinguishable both by
the sight and touch; the other, denominated _gas_, or _gaseous fluids_,
have the appearance of air, and are not perceptible either to the sight
or touch, except under certain circumstances. The latter are principally
oxygen (21), azote or nitrogen, and hydrogen (45). We shall at present
have occasion to speak only of the first.


                            GASEOUS FLUIDS.

21. _Oxygen_, like caloric, is a fluid never found in an uncombined
state. It forms one of the component parts of the air that we breathe,
and of the water we drink; but it approaches nearest to a state of
purity in combination with caloric (18), when it has the name of _oxygen
gas_. It was formerly called _vital air_, because no breathing animal
can live for a moment in any air or gas which has not in it a mixture of
oxygen; every kind of combustible burns with great splendour in it, and
without it ceases to burn. It unites with a great number of substances,
and changes both their appearance and properties in a very remarkable
manner. Of the metals it entirely destroys the metallic lustre, and
gives them an earthy form and texture. Substances in this state have the
name of _oxides_.

Lead, for instance, combined with oxygen becomes the well─known red and
heavy substance used by painters, under the name of minium or red lead
(239). This, if deprived of its oxygen, loses its red colour, and
returns to its former metallic state. Some of the metals are oxidized by
merely being exposed to moisture. Thus the rust which is so readily
contracted by iron is an oxide of that metal, produced by its attracting
oxygen from the air or from water.


                                 ACIDS.

22. It is one of the most remarkable properties of oxygen to impart to
most of those bodies called _acids_ their peculiar character of acidity.
Oxygen does not itself possess the properties of an acid, nor is it an
essential ingredient in all acids, though it is the acidifying principle
in the greater number of them.

23. _Acid_ is a word originally synonymous with sour. It has, however,
been gradually extended in its signification, and now comprehends all
substances possessed of the properties of exciting upon the tongue the
sensation called sour; of changing the blue colours of vegetables to
red; of uniting with water in almost any proportion; of combining with
alkalies (42), metallic oxides, and earths, and of forming with them
certain compounds called _salts_.

24. _Sulphuric Acid_, or _Spirit of Vitriol_, as it is commonly called,
is a liquid of a somewhat oily consistence, transparent and colourless
as water, formed by a combination of oxygen (21) with sulphur (46). Like
other acids, it never occurs in nature in a pure state, for it can no
sooner be formed than it unites with earths (31), alkalies (42), or
metals, and forms, with them, several well─known salts, which have the
name of _sulphats_. Thus alabaster (192) and Epsom salts (199) are
respectively formed by an union of sulphuric acid with lime and
magnesia, and are denominated by chemists sulphat of lime and sulphat of
magnesia. In like manner, blue vitriol (209) is sulphat of copper; green
vitriol (208), sulphat of iron; and white vitriol (210), sulphat of
zinc.

25. _Phosphoric Acid_ is produced by a combination of oxygen (21) with
phosphorus (47); and, when obtained in a state of purity, is not a
fluid, but a white and flaky substance. This acid, when combined with
mineral productions, forms those salts which have the name of
_phosphats_. It is very soluble in water; and, in dissolving, makes a
hissing noise, similar to that produced by plunging hot iron into water.

26. _Carbonic Acid_ is a compound of oxygen (21) and carbon, or pure
charcoal (48): and in a state of gas (20) it forms a constituent part of
the atmospheric air. It is also emitted in great abundance from wine,
beer, and other liquors, in a state of fermentation, and is sometimes
found in the lowest parts of mines, where it is known to the miners by
the name of _choke damp_, from the circumstance of its immediately
extinguishing flame, and suffocating all animals that are immersed in
it. This gas, which was formerly called by chemists _fixed air_, is
about twice the weight of common air. In combination with lime it forms
chalk, marble, and limestone; and it constitutes part of several other
mineral substances, which are thence denominated _carbonats_.

27. _Fluoric Acid_ is a gas of very singular nature, which is held in
combination with lime, in the Derbyshire or fluor spar (194); and may be
separated from it by pouring sulphuric acid, or spirit of vitriol (24),
upon powdered spar, in a leaden vessel called a retort, and applying to
it a gentle heat. The salts formed by fluoric acid have the name of
_fluats_.

28. The _Boracic_ is a peculiar kind of acid, which, in combination with
soda (200), forms the substance that we import from the East Indies
under the name of borax (204). When extracted from borax this acid does
not assume the form of a fluid, but appears in thin six─sided scales or
flakes, of white colour, which adhere slightly together, and feel
somewhat greasy in handling. To the taste it is at first sour, then
bitterish; and at last it leaves an agreeable sweetness on the palate.

29. _Muriatic Acid_ is a gas formed by the combination of oxygen (21)
with some base that is not yet known. It is an invisible and elastic
fluid, which, in mechanical properties, resembles common air, and has a
pungent and very peculiar smell. This gas unites with alkalies (42),
earths (31), and the oxides (21) of metals; and with them forms the
compounds called _muriats_, of which common salt, or muriat of soda
(202), is one of the principal. The liquid muriatic acid, or muriatic
acid gas combined with water, is frequently denominated _spirit of salt_
(202).

30. _Nitric Acid_ is a compound of oxygen and azote, or nitrogen, in the
proportion of twenty─five parts, by weight, of the latter to
seventy─five of the former. It is one of the constituent parts of nitre,
or saltpetre (206); and, in a pure state, is transparent and colourless,
like water. By the action of light, however, it soon becomes yellow;
and, if exposed to the air, it emits yellow fumes, which even tinge the
air of the same colour. To the taste it is extremely acid. It dyes the
skin a yellow colour, which is very difficult to be removed; and it is
so corrosive as to destroy almost every substance into which it
penetrates. If poured upon oils, it sets them on fire. With various
bases it forms compounds called _nitrats_. This acid, which hitherto has
never otherwise been obtained than mixed with water, is chiefly known in
commerce by the name of _aqua fortis_ (206).


                                EARTHS.

31. The solid contents of the globe are composed of several elementary
substances, amongst which have been enumerated no fewer than nine
different kinds of earth:

    1. Silex.
    2. Alumine.
    3. Zircon.
    4. Glucine.
    5. Yttria.
    6. Barytes.
    7. Strontian.
    8. Lime.
    9. Magnesia.

These, when freed from foreign admixture, are, for the most part, of
white colour, not soluble in water, not combustible, and do not exceed
four times the weight of water.

32. The whole of these earths have, till lately, been considered simple
and uncombined substances; but, by the discoveries of Sir Humphrey Davy,
it has been ascertained that four of them have a metallic basis, and are
in fact metallic oxides, or compounds consisting of a metal united with
oxygen (21). These, which have the same affinity with their respective
bases as rust has to iron, are silex, lime, barytes, and alumine. Until,
however, some further light be thrown upon their nature and
constitution, they must continue to hold their former situation of
simple earths.

33. _Silex_, or _Siliceous Earth_, is the basis of all substances known
by the name of quartz and silex (76). In a state of nature it has never
been found pure; but, in combination with other substances, it abounds
in almost every country of the globe. Common flint (90) contains
ninety─seven parts in a hundred of silex: it consequently has given its
name to this earth, _silex_ being the Latin word for flint. When
purified it is a white powder, the particles of which are harsh to the
touch, as if they consisted of very minute grains of sand. It is not
quite three times as heavy as water, and has neither taste nor smell.
Water will not dissolve it, nor any kind of acid, except fluoric. Sir H.
Davy has discovered it to have a metallic basis, to which he has given
the name of _silicium_.

34. _Alumine_ is a kind of earth, so called from its forming the basis
of alum (197). It is soft, compact, and tenacious; about twice the
weight of water, and, when breathed upon, has a smell which is peculiar
to all clayey productions. In the fire it shrinks, and becomes so hard
as even to yield sparks when struck against steel. It readily absorbs
water, and is dissolved by most acids. Some writers state that pure
alumine has been discovered in a native state near Halle, in Germany. It
is found in a crystallized form, and nearly in a state of purity, in the
Oriental ruby and sapphire. The name of _argil_, or clay, has sometimes
been applied to it; but, in mineralogy, this name has usually been given
to a mixture of alum, quartz, and other substances. Sir H. Davy has
obtained from alumine a metallic basis, called _aluminum_.

35. _Zircon_, when freed from those substances with which it is
combined, is a white and somewhat rough powder, insipid to the taste,
insoluble in water, and about four times as heavy as that fluid. It is
found in the two kinds of precious stones called jargoon and hyacinth,
and has not hitherto been applied to any useful purpose.

36. _Glucine_ is a kind of earth of peculiar nature, which is found in
the emerald and beryl, and, when purified, forms a soft and white
powder, without smell, and of sweetish taste. To the last of these
qualities it is indebted for its name, which is derived from a Greek
word signifying sweet. It is somewhat unctuous to the touch, and about
three times as heavy as water. The uses of this earth, whatever they may
be, are not known.

37. _Yttria_ is an earth which, among other particulars, differs from
glucine by its weight, as it is nearly five times heavier than water. In
a natural state it occurs as the basis of a black Swedish mineral,
called gadolinite. When cleansed, by chemical process, from all its
impurities, it is a fine, white, and inodorous powder.

38. _Barytes_ is a white, porous, and very heavy earth, which can only
be obtained pure by chemical process. It is easily reduced to powder,
and is soluble in all kinds of acids. To the taste it is harsh and
caustic; and, if taken into the stomach, proves an extremely virulent
poison. In some respects it agrees with the alkalies (42), particularly
in its property of changing blue vegetable colours to green, and in
corroding, like them, though with less energy, all kinds of animal
substances. From these circumstances it has sometimes been denominated
an alkaline earth. Saturated with sulphuric (24) and carbonic acid (26),
it constitutes the minerals denominated sulphat and carbonat of barytes
(196). It has been discovered to have a metallic base, which is called
_barium_.

39. _Strontian_ is an earth which, like barytes, is not found otherwise
than in combination with sulphuric and carbonic acids. It occurs in
various parts of the world, and, when purified, forms a porous mass of
greyish white colour, acrid taste, and somewhat alkaline nature. This
earth converts vegetable blue colours to green, but does not act so
strongly on animal bodies as barytes, nor is it poisonous, like that
substance.

40. _Lime_, the basis of all those substances which are denominated
_calcareous_, is only to be obtained in a state of purity by artificial
process. Combined with carbonic acid (26) it forms limestone (140),
chalk, and marble; all of which are capable of being converted into lime
by burning. Lime may also be obtained from oyster and other sea shells.
When pure, it is of white colour, and moderately hard substance, though
it is easily reducible to powder. Its taste is burning and acrid; and,
like the alkalies, it changes vegetable blue colours to green. It has
likewise the property of corroding and destroying animal substances.
Lime, when pure, absorbs water rapidly, becomes hot, and falls into
powder. Even if exposed to the open air it gradually attracts moisture,
and assumes a powdery form; soon after which it becomes saturated with
carbonic acid (26) from the atmosphere, and is thereby again converted
into carbonat of lime (140). It occurs abundantly in almost every
country, but always in combination with some acid, carbonic (26),
sulphuric (24), boracic (28), fluoric (27), or phosphoric (25). This
substance has a metallic basis, which has been denominated _calcium_.

41. _Magnesia_ is a light and perfectly white kind of earth, of soft
powdery appearance, without taste or smell, and somewhat more than twice
as heavy as water. It is not found in this pure state in nature, but may
be prepared from Epsom salt, which consists of magnesia in union with
sulphuric acid (24). The slightly acrid taste that is perceptible in the
magnesia used in medicine arises from a portion of lime which it
contains. This substance does not dissolve in water, but is soluble in
every kind of acid. It has the property of changing delicate blue
colours to green.


                               ALKALIES.

42. Alkalies are substances which enter into the composition of several
kinds of minerals, and are known by their property of changing the
colour of blue vegetable juices to green, and by a peculiarly acrid,
caustic, and nauseous taste, which it is impossible to describe, but
which, after it has been once experienced, will easily be recollected.
Alkalies corrode and dissolve animal substances, and unite with oil and
fat in such manner as to form the well known compound called soap. They
readily dissolve in water; and, when mixed with acids, form what have
been denominated neutral salts.

43. The alkalies at present known are three in number; _potash_ (205),
_soda_ (200), and _ammonia_ (207). Of these the two former, although
till lately they have been considered simple substances, have been shown
by Sir H. Davy to have metallic bases.


                          SIMPLE COMBUSTIBLES.

44. By this term we are to understand all those mineral substances,
capable of combustion, which have not been discovered to consist of more
than a single component part. They are four in number; _hydrogen_,
_sulphur_, _phosphorus_, and _carbon_.

45. _Hydrogen_, as its name imports, is a principal constituent part of
water; for, singular as it may appear, that well─known fluid is formed
by a combination of two species of air or gas, called hydrogen and
oxygen (21), and in the proportion of about fifteen parts of the former
and eighty─five parts of the latter. This gas had formerly the
denomination of _inflammable air_, and has long been known in mines
under the name of _fire─damp_. It is about twelve times lighter than
atmospheric air. When pure it soon destroys such animals, and
extinguishes all such flaming substances, as are immersed in it. Mixed
with atmospheric air, it explodes with great violence on the application
of any ignited body.

46. _Sulphur_ is a simple combustible substance, of yellow colour, which
is found pure, or native, in several parts of the world, and is
sufficiently familiar to us under the name of _brimstone_ (211). It
strongly attracts oxygen (21), and is thereby converted into sulphuric
acid (24). It frequently occurs in combination with mineral substances,
such as arsenic, antimony, copper, and other metallic ores.

47. _Phosphorus_ is a combustible substance which, when pure, somewhat
resembles bees’─wax both in colour and consistence; and, when exposed to
the air under the usual temperature of our atmosphere, is luminous in
the dark, and has a smell somewhat resembling that of garlic. It is so
combustible that, when melted, it should be kept under water, as it
cannot be exposed to the air during this process without great risk of
catching fire. This substance is not known in a native state; and the
whole of what is used in philosophy and commerce is obtained by
different artificial processes. In union with oxygen (21) it becomes
converted into an acid, called _phosphoric acid_ (25), and, under this
form, in conjunction with lime, it constitutes the bones of men and
animals. The greater part of the phosphorus of the shops is obtained
from bones.

48. _Carbon_ is a name given to the pure inflammable part of charcoal.
It is abundantly diffused throughout nature, for it enters into the
composition of several minerals, and of all vegetable and animal bodies.
The purest form under which carbon is known to exist is in the diamond
(50). It may, however, be obtained sufficiently pure, for all common
purposes, by burning a piece of wood, covered with sand, in a vessel
called a crucible. In combination with oxygen (21) it forms carbonic
acid (26). Carbon is a chief component part of pit─coal (217), petroleum
(213), and other bituminous substances.


────────────────────────────────────────────────────────────────────────




                            CLASS I.—STONES.

                        ORDER I.—EARTHY STONES.

                                ───────

                 _I. HARD: those which scratch Glass._

                                ───────

49. OF GEMS IN GENERAL.

Gems, or precious stones, as they are frequently called, are, for the
most part, transparent, and have a vitreous or glassy appearance. Their
different colours are occasioned by metallic oxides (21) of various
kinds, with which they are impregnated. Some writers have classed them
by their colours, but this is a very uncertain mode, as different gems
have not unfrequently the same colour; and, in many cases, the same gems
are of different colours. The usual distinction of gems into Oriental
and Occidental is also liable to error, as the best gems, from whatever
part of the world they are brought, are always called Oriental. The most
estimable of all the kinds are the diamond (50), ruby (54), emerald
(67), and sapphire (53); and stones a grain in weight, and equal in
quality, are valued in the following proportions, at 8_l._ per carat for
diamonds, 4_l._ for rubies, and 3_l._ for each of the others. The
amethyst (79), topaz (61), and aqua─marine (61), are considered of
nearly equal value with each other; and the garnet (70) is the cheapest
of precious stones.

The ancients engraved upon several kinds of gems; but they appear to
have been ignorant of the art of cutting the diamond, the ruby, and the
sapphire, which were too hard for them to operate upon. The emerald and
the noble opal (102) were too highly esteemed as precious stones to have
often found their way into the hands of engravers. It has been asserted
that the ancients did not use the topaz for engraving; but there is
extant a beautiful _intaglio_, representing an Indian Bacchus, which is
said to be a topaz. The garnet was often engraved upon: and there are
many master─pieces of the art in calcedony (91) and carnelian (93.) Onyx
and sardonyx (92) were employed for that species of engraving in relief
called _cameos_; and, in many instances, it is pleasing to observe with
what dexterity the ancient artists availed themselves of the different
colours in the alternate zones to express the different parts and shades
of their figures.

Most of the gems may be imitated by artificial preparations of glass,
coloured by different metallic substances; and it is not easy, by mere
inspection, to distinguish the better kinds of factitious stones from
real gems. They are, however, discoverable by a deficiency of lustre,
and being so soft as, even in the most perfect kinds, to yield to the
point of a steel instrument.

The cutting and polishing of gems is the work of the lapidary, and is in
general thus performed:—The shape most proper to be given to any
particular gem being determined on, the stone is cemented to the end of
a stick, and the different facets are formed by a mill contrived for the
purpose. This mill is a plate of copper, or an alloy of lead and tin, to
which an horizontal motion is given by very simple machinery, and the
surface of which is charged either with diamond powder and oil, or with
fine emery and water. A thick peg of wood called a gauge, pierced with
small holes in all directions, is set upright on the lapidary’s bench,
close to the mill, and the process of shaping the facets thus takes
place. The stone is placed on the surface of the mill, the opposite end
of the stick to which it is cemented being inserted in one of the holes
of the gauge. In this position it is kept steady by the workman, with
his right hand, whilst, with the other, he puts the mill in motion. The
skill of the lapidary depends on regulating the velocity of the mill,
and pressing with more or less force on the stick, with an almost
imperceptible tendency to one or other direction in different stages of
the work, examining each facet at very short intervals, in order to give
as great precision as possible to its size and form. This part of the
business being completed, the cutting mill is taken out, and replaced by
one of brass, on which the polishing is performed by means of fine emery
(58), tripoli, and rotten stone (119), exactly in the same manner as is
practised in the first stage of the process for setting the facets.


                                DIAMOND.

50. _The DIAMOND, or ADAMANT of the ancients, is the most valuable of
gems, and the hardest of all known bodies; when pure, it is perfectly
transparent._

_In a rough state, diamonds have usually either the form of rounded
pebbles, with a shining surface, or they are crystallized in the shape
of octohedrons, or double four─sided pyramids. (Pl. II, Fig. 5, 6.)
Though for the most part colourless, they are sometimes yellow, green,
blue, blackish, or rose─coloured._

The best diamonds are brought from the East Indies. The principal mines
are those of Raolconda and Coulour, in the province of Golconda; and
that of Soumelpour, or Goual, in Bengal. At Raolconda they are found in
the deep crevices of rocks. Persons, by means of long iron rods, with
hooks at the end, draw out from these crevices the loose contents, and
afterwards wash them in tubs, for the purpose of discovering the
diamonds.

The first discovery of diamonds at Coulour was about two centuries ago,
by a countryman, who, on digging his ground to sow millet, accidentally
found one of these stones of large size. From that period the whole
adjacent plain began to be searched to the depth of from ten to fourteen
feet; and the work was, at one time, so extensively pursued, that nearly
6,000 persons were employed in it. At Soumelpour the diamonds are found
amongst the sand and gravel of the river.

Diamonds are likewise found in the island of Borneo, and in several
parts of South America. The mode by which they are obtained from one of
the rivers of Brazil has been described by Mr. Mawe. The current is
turned, and part of the bed of the river being laid dry, the mud is
taken up and washed, by negroes, in places prepared for the purpose,
through which a portion only of the stream is allowed to flow. As soon
as all the earthy particles have been washed away, the gravel─like
matter that remains is raked together, the stones are thrown out, and
what diamonds happen to be present are found amongst the refuse that is
left.

To ascertain whether a stone, that has been found, be really a diamond,
the workmen have a mode of placing it upon a hard substance, and
striking it with a hammer. If it either resists the blow or separate
into leaves, it must be a diamond; but, in the latter case, the
discovery is sometimes made at an immense expense, as, by thus
diminishing the size, its value must also, of course, be greatly
diminished.

Diamonds are generally exported from Madras in a rough state; and in
small parcels neatly sewed in muslin, and sealed by the merchants who
send them. These, we are informed by Mr. Milburne in his valuable work
on oriental commerce, are, for the most part, sold in Europe by the
invoice, as it is called; that is, without being opened: and he says
that they are always found to contain the value for which they were sold
in India.

Of all transparent substances, none for brilliancy can be compared with
the diamond. Its hardness is such, that no steel instrument whatever can
make any impression upon it. Notwithstanding this, at a temperature not
so high as that which is required for the melting of silver, it
gradually dissipates and burns. Diamonds have been shown to consist
principally of carbon or charcoal in a pure and crystallized state.

The ancients, ignorant of the art of cutting diamonds, were contented to
set them in a native state; and for this purpose they preferred such
stones as had naturally a crystallized form. The four large diamonds
which ornament the clasp of the Imperial mantle of Charlemagne, and
which are still preserved in Paris, are uncut stones of this
description. The extreme hardness of the diamond baffled all attempts to
polish it in such manner as to exhibit its peculiar beauty, until the
year 1456, when a young man of Bruges, whose name was Berquin,
endeavoured to polish two diamonds by rubbing them against each other.
Having succeeded in this, he next constructed a wheel, on which, by
means of diamond powder, he was enabled to cut and polish these gems in
a manner beyond his greatest expectation. Since this period the art of
polishing them has been greatly improved both by the Dutch and British
jewellers.

In the choosing and valuing of diamonds in a rough state, attention is
paid to their colour, their being free from extraneous matter, and their
shape. Those that are most perfect are crystalline, and resemble a drop
of clear spring water, in the middle of which is to be perceived a
strong light, that plays with great spirit on moving them about. When
they have a yellowish or greenish tinge they are considered to be bad.
Many diamonds have a kind of confused structure, which lapidaries
compare to knots formed in wood. These are rejected, from the
impossibility of polishing them properly.

Mr. Mawe remarks that diamonds, when rubbed together, have a peculiarly
and scarcely to be described grating sound, which is one of their most
remarkable characteristics. By this alone rough diamonds may be
accurately and expeditiously distinguished from every other gem.

It is usual to cut diamonds into three principal forms, called
_brilliant_ (Pl. II, Fig. 7), _rose_ (Fig. 8), and _table_ diamonds
(Fig. 9). Brilliants are, for the most part, cut from such of the stones
as have naturally a crystallized shape, and rose diamonds from the flat
varieties. The former are so called from their great lustre, in
consequence of the facets on both sides being cut. These are always set
upon a black ground, whilst rose diamonds, which are much thinner, are
set upon a white foil speckled with black, for the purpose of adding to
their lustre. Rose─cut diamonds are of course much less estimable than
brilliants; so much so indeed, that of late many of them, brought from
Holland, have been re─cut into brilliants, notwithstanding the
additional expense, and the loss of size necessarily attendant on this
operation. The table diamond is the least beautiful of any. This mode of
cutting is only adopted for such stones, or rather fragments, as, with a
considerable breadth, have only a very trifling depth. The
diamond─cutters of England are considered to be the best in Europe, but
their number is so small as to occasion many stones to be sent to
Holland to be cut.

The value of diamonds is ascertained by their weight in carats; and this
value increases, in a very high ratio, according to their magnitude. For
instance, a diamond weighing one carat will be worth about 10_l._ whilst
another of five carats will be worth 150_l._ and of ten carats
800_l._[2] This rule, however, can only be taken for diamonds of twenty
carats and under. The larger ones, in consequence of the scarcity of
purchasers, are generally disposed of at prices greatly inferior to
their estimated worth. The value of some diamonds that are peculiarly
perfect exceeds the above ratio; whilst, for a stone that is cloudy,
foul, or of bad colour, even three quarters of the estimated value will
perhaps be deducted.

Footnote 2:

  A Carat is equal to four jeweller’s grains, seven grains of which are
  equal to six grains troy. To ascertain the value of wrought diamonds
  the weight must be doubled, about half being supposed to be lost in
  the working. This sum must be multiplied into itself, and the product
  by two. Thus to find the value of a diamond of twenty carats 20 × 2 =
  40 × 40 = 1600 × 2 = 3,200_l._

No diamonds are so valuable as those that are perfectly transparent, and
of snow─white colour. The green and yellow varieties are, however, much
esteemed: the blue kinds were formerly more valued than at present; and
the least valuable are those that have a grey or brownish tint. Black
diamonds are much prized by collectors.

The principal use of the diamond is in jewellery. It is also used by
lapidaries, for slitting hard stones, and for cutting and engraving upon
other gems; by clock─makers in the finer kinds of clock─work; in the
glass─trade for squaring large pieces or plates of glass, and among
glaziers for cutting their glass.

The largest diamond ever known (if it be such, and not a white topaz, as
some people have imagined) is in the possession of the Queen of
Portugal, and weighs 1,680 carats, or more than _eleven ounces_. It was
found in Brazil, and sent to Lisbon in the year 1746. It is still uncut,
and has been valued at 5,644,800_l._

The Rajah of Mattan, in the island of Borneo, possesses a large diamond,
shaped like an egg, with an indented hollow near the smaller end. It was
found in that island about eighty years ago, is said to be of the finest
water, and to weigh 367 carats, or more than two ounces and a quarter.
Several years ago the Governor of Batavia, desirous of purchasing this
gem, sent a Mr. Stuvart to the Rajah, authorizing him to offer for it
150,000 dollars, two large brigs of war, with their guns and ammunition,
together with a certain number of great guns, and a quantity of powder
and shot. The Rajah, however, refused to deprive his family of so
valuable an hereditary possession; for the Malays not only attach to it
the miraculous power of curing all diseases by means of water in which
it is dipped, but also believe that the fortune of the family is
sustained by its continuing in their possession.

Tavernier, the French Traveller, saw in the possession of the Great
Mogul a diamond which weighed near 280 carats. In form and size it
resembled half a hen’s egg. This diamond had been obtained from the mine
of Coulour, about the year 1550; and was valued at more than 700,000_l._
sterling.

The sceptre of the Emperor of Russia is adorned with an oriental diamond
about the size of a pigeon’s egg, which weighs 195 carats. This diamond
is said to have once been placed as the eye of an idol in Seringham, in
the Carnatic. A grenadier, who had deserted from the French service in
India, contrived to become one of the priests of the idol, in the hope
of being able to steal this eye. He at length effected his purpose, and
escaped with the diamond to Madras, where he sold it to the captain of a
ship for a sum equal to 2,500_l._ of British money. It was afterwards
transferred to a Jew for 18,000_l._ Coming into the hands of a Greek
merchant, he offered it for sale at Amsterdam, in 1766; and the Russian
Prince Orloff bought it for the Empress Catharine for about 90,000_l._
sterling, and an annuity of 4,000_l._ during the life of the person who
sold it.

The _Pitt_, or _Regent diamond_ (Pl. II, Fig. 10), which lately was set
in the handle of the sword of state of Buonaparte, and is now possessed
by the king of France, is a brilliant of the most beautiful kind, and
weighs 136¾ carats. It was brought from India by Thomas Pitt, Esq.
Governor of Fort George. Mr. Pitt has himself stated, respecting it,
that, in December, 1701, whilst resident in Madras, several valuable
stones, in a rough state, were brought to him for sale by an eminent
diamond merchant. One of these, the diamond here spoken of, was so large
that the merchant asked for it the sum of 85,000_l._ After much
bargaining, Mr. Pitt purchased it for 20,400_l._ He afterwards sold it
for 135,000_l._ to the Regent Duke of Orleans; and by him it was placed
among the crown jewels of France.

The _Pigot diamond_ weighs forty─seven and a half carats. This, which is
an extremely fine stone, was disposed of by lottery, in 1800, for
22,000_l._; and is now in the possession of Messrs. Rundell and Bridge,
jewellers in London.

A large star, cross, and chain, worn on grand gala days by the Prince of
Brazil, as Sovereign of the different Portuguese orders of knighthood,
are each ornamented with a great number of magnificent diamonds, set in
gold. The centre diamond of the star is alone valued at 800,000_l._

When the diamond is rubbed it will attract bits of straw, feathers,
hairs, and other small objects; and if exposed to the rays of the sun,
and immediately taken into a dark place, some diamonds will appear
luminous.


                             ZIRCON FAMILY.

51. _JARGOON is a gem usually of smoky yellow or brownish colour, and
sometimes limpid: if placed upon any object, it exhibits of it a very
distinct double image._

_The primitive form of its crystal is an octohedron (Pl. II, Fig. 5),
but it is frequently crystallized in right─angled prisms, terminated by
four─sided pyramids._

In hardness this stone does not much exceed that of the emerald. The
greyish white and yellowish white varieties of jargoon are valuable
chiefly on account of their resemblance to the diamond. The
darker─coloured varieties can be deprived of their colour by heat; and,
in this state, though in lustre they are infinitely inferior to them,
they are sometimes substituted for diamonds. Jargoons are now seldom
used except for the jewelling of watches and time─pieces. About a
century ago, they were much used in mourning ornaments, for which the
dark tone of their colour, and their almost adamantine lustre, were
supposed to be peculiarly appropriate.

The jargoon is principally brought from the island of Ceylon; but it is
occasionally found in France, and Spain, and in granite rocks near
Cuffel, in Dumfrieshire, Scotland.

52. _The_ HYACINTH, _or_ JACINTH, _is a dark orange─red variety of
jargoon_. It is also chiefly imported from Ceylon, where it is generally
found in the sand of rivers, in irregularly round pieces, but seldom of
large size without flaws.

This stone is indebted for its name to a supposed resemblance in colour
to that flower, which, according to the Pagan mythology, Apollo raised
from the blood of his favourite youth, Hyacinthus.

When bright, and free from flaws, the hyacinth is a superb ring stone;
but it is not of usual occurrence in modern jewellery.


                              RUBY FAMILY.

53. _The ORIENTAL SAPPHIRE is a gem of blue colour, the shades of which
vary from a full and deep tint to a nearly colourless appearance, and
sometimes it is party─coloured._

_It is found crystallized in six─sided pyramids much lengthened and
joined base to base (Pl. II, Fig. 13); and also in rounded or
pebble─shaped fragments. It has a foliated texture, is extremely hard,
and about four times as heavy as water._

We are chiefly indebted for the sapphire to the East Indies and the
Island of Ceylon, where it is found amongst the sand of the rivers. When
brought into Europe, it is cut by means of diamond powder, and polished
with emery. It is now usually set with a foil of its own colour; but it
was formerly the practice, instead of foil, to place under this stone
the blue part of a peacock’s feather.

In hardness the sapphire ranks next to the ruby (54); and in value it is
about equal to the emerald (67). A good sapphire of ten carats’ weight
is worth about fifty guineas. In the Museum of Natural History at Paris
there is a sapphire which weighs upwards of sixty─six carats: it was
placed there from the wardrobe of the crown.

We are informed by M. Hauy that sapphires are found in Bohemia and
France, particularly in one part of the Ville du Puy, among the sand of
a rivulet near Expailly. In the summer─time, when the rivulet is nearly
dry, they are collected by persons, each of whom is furnished with a
small tray and a linen bag. Where─ever there are small depressions in
which the water has been stationary, these persons enter them, and fill
their trays with the sand. This they wash in water in such manner that
the lighter particles are carried away; whilst the heavier ones of
gravel, sapphire, and other articles, remain at the bottom.

Some sapphires exhibit a kind of opalescence, or whitish floating light
in their interior. Sapphires lose all their colour in the fire; and,
after having been subjected to heat, they are so hard and transparent as
sometimes to be sold for diamonds.

54. _ORIENTAL RUBY is a precious stone of intense and bright red colour,
occasionally varied with blue, and sometimes party─coloured._

_In the general form of its crystals it much resembles the sapphire
(53)._

The ruby is imported into this country from the East Indies, though
seldom in a rough state, as the stones are almost always first cut by
the Indians for the purpose of ascertaining their value. They are said
to be found in the sand of certain streams near the town of Sirian, the
capital of Pegu; and with sapphires in the sand of rivers in Ceylon. But
they are so seldom seen of large size, that a ruby above thirty─one
carats’ weight, of perfect colour, and without flaws, is even more
estimable than a diamond of equal weight. The ruby is usually set with a
foil; but, if peculiarly fine, it is sometimes set without bottom, that
the stone may be seen through.

Tavernier, the Eastern traveller, states that, in the throne of the
Great Mogul, he saw 108 rubies, which, on an average, weighed from 100
to 200 carats each. Among the jewels of the King of Candy, that were
sold by auction in London, on the 13th of June, 1820, was a ruby which
measured two inches in length, and one inch in breadth. It was, however,
interesting only as a specimen for a cabinet, for it had, in various
directions, a great number of small hair─like tubes running through it.

The hardness of this stone is such that the ancients do not appear to
have possessed the art of cutting it; and, in the improvements which of
late have been made by Mr. Earnshaw in the construction of time─keepers,
no stones have been found sufficiently hard for jewelling the holes,
except the ruby and the diamond.

There are several modes of counterfeiting rubies; and some persons have
succeeded so well in imitating these stones, that even the most able
lapidaries, till they try the hardness, may be deceived.

55. _The ORIENTAL AMETHYST is an extremely rare gem, usually of purple
colour, apparently formed by an union of the colouring matter of the
sapphire and the ruby_. This stone, if heated, loses its colour, and
becomes transparent. After this process its brilliancy is such that it
is scarcely distinguishable from the diamond; and, in jeweller’s work,
it is occasionally substituted for that gem. The common amethyst (79),
or that which is chiefly seen, is nothing more than a violet─coloured
rock crystal (78).

56. _The ORIENTAL TOPAZ and EMERALD are each varieties of the oriental
ruby, the former straw─coloured and the latter green_. This kind of
emerald is imported from Pegu, and some other parts of the East Indies,
and is an extremely rare gem.

57. _The SPINEL and BALAIS RUBY are two kinds of precious stones, which
differ from each other principally in colour, the former being of a
carmine, and the latter a cochineal red._

_They vary from the oriental ruby (54) in being less hard; in the
primitive form of their crystals being regular octohedrons (Pl. II, Fig.
5), and in their not being much more than 3 times heavier than water._

Although these two kinds of rubies are inferior, both in lustre and
colour, to the oriental ruby; yet, when they exceed a certain size, they
are much esteemed. A spinel that weighs more than four carats is valued
at half as much as a diamond of the same weight, and is not unfrequently
imposed upon ignorant purchasers for the oriental species. It is easily
wrought, takes a high polish, and is certainly a beautiful gem. Being
too expensive for necklaces, it is usually set in rings and brooches,
surrounded by brilliants.

The spinel ruby is found amongst sand, in one of the rivers of Ceylon,
which flows from the high mountains, towards the middle of the island.
It is also found in Brazil; and in Hungary, Bohemia, and Silesia.

The Balais ruby is so named from Balacchan, the Indian appellation of
Pegu, from which country it is chiefly imported.

58. _EMERY is a very hard opaque mineral, of blackish or bluish grey
colour, which is chiefly found in shapeless masses, and mixed with other
minerals. It is about four times as heavy as water._

The best emery is brought from the Levant, and chiefly from Naxos, and
other islands of the Grecian Archipelago, where it occurs abundantly, in
large, loose masses, at the foot of primitive mountains. It is also
found in some parts of Spain; and is obtained from a few of the iron
mines in our own country.

In hardness it is nearly equal to adamantine spar; and this property has
rendered it an object of great request in various arts. It is employed
by lapidaries in the cutting and polishing of precious stones; by
opticians, in smoothing the surface of the finer kinds of glass,
preparatory to their being polished; by cutlers, and other manufacturers
of iron and steel instruments; by masons, in the polishing of marble:
and, in their respective businesses, by locksmiths, glaziers, and
numerous other artisans.

For all these purposes it is pulverized in large iron mortars, or in
steel mills; and is afterwards separated, according to the several
degrees of fineness that are required, by washing it in water, and
suffering the grosser particles to deposit themselves. By this operation
the finer particles, which remain suspended in the water, and which are
obtained by decanting the water off, and suffering it to stand for a
considerable time, are separated. The particles first deposited are
again ground, and again agitated in the water, to separate the finest.
By these successive operations the emery is reduced to a powder so fine
that, when rubbed between the fingers, it communicates no sensation
whatever of grittiness. In general those particles only of the emery
which remain suspended in the water, after it has stood about half an
hour, are used to polish metals.

59. _ADAMANTINE SPAR, or IMPERFECT CORUNDUM, is a very hard and nearly
opaque stone, which varies much in colour, but is chiefly grey, with a
greenish, brown, or bluish tint._

_It is usually found in the form of six─sided prisms, but it sometimes
occurs in shapeless masses, has a foliated texture, and is about four
times as heavy as water._

The name of adamantine spar was given, by the British lapidaries, to
this substance from its hardness being nearly equal to that of the
diamond. It was originally discovered among the granite rocks of China;
but it has since been found, and in greater purity, in Bengal and
Ceylon.

In a powdered state this substance has long been used by the artists of
India and China for the cutting and polishing of precious stones, and
even of the diamond; but, though it will in some degree operate upon
that gem, it is not sufficiently hard to bring out the peculiar beauty
of it in a degree at all comparable to that which is effected by the
European lapidaries with diamond powder. The Chinese also use adamantine
spar for polishing steel, and in the composition of the finer kinds of
porcelain or earthenware. For the cutting of seals and precious stones
European workmen consider it preferable to emery; but, for minute
engraving, it is much inferior to diamond powder.

60. _CHRYSOBERYL is a gem of yellowish or brownish green colour, harder
than quartz (76), and sometimes transparent; but often only
semi─transparent, in which case it exhibits a bluish light, floating in
the interior of the stone._

_It is usually found in rounded pieces, but is sometimes crystallized in
compressed six─sided prisms, and in double six─sided pyramids._

So little is this gem in request in Europe, that it is seldom to be
found in the possession of jewellers; but in Brazil it is considered
inferior only to the diamond. It is usually procured from South America;
yet it occurs in Saxony; and, with the ruby and sapphire, amongst sand
in the rivers of Ceylon.

Such is the hardness of the chrysoberyl, that, when properly polished,
which is a difficult operation, it is capable of receiving a lustre
nearly equal to that of the diamond. We are informed that, a few years
ago, a considerable number of these gems were imported into this country
from Brazil, but that the greater part of them were entirely spoiled by
inferior workmen, and that the rest were so ill─cut that they remained
unnoticed, and without value. The smaller stones are said to appear to
most advantage in circular ear─drops; and the larger specimens form
necklaces and ring stones of great beauty.

The variety which exhibits an opalescent appearance, or presents a
bluish light, undulating as it were in the interior of the stone, and
changing its situation according to the position of the observer, is
chiefly valuable as an article of curiosity: the transparent kind is
always preferred by the jeweller.


                             SCHORL FAMILY.

61. _The TOPAZ is a gem usually of a wine─yellow colour, but sometimes
orange, pink, blue, and even colourless, like rock_ _crystal; of a
lamellar or foliated structure, harder than quartz, but not so hard as
ruby._

_It varies considerably in its crystallization; is 3½ times heavier than
water; and, when placed upon any object, shows a double image of it._

The name of topaz is derived from an island in the Red Sea, where the
ancients found a stone, but very different from ours, which they
denominated topaz. The best topazes are of a deep colour, and are
imported from Brazil; the most brilliant ones are supposed to be those
of Saxony; but the latter are generally of very pale colour. This
species of gem is found in many parts of Europe, but defective in
transparency, and sometimes even opaque. It occurs in large crystals,
and rolled masses, in an alluvial soil (269), in the upper parts of
Aberdeenshire, Scotland; and in veins, along with tin─stone, at St.
Anne’s, in Cornwall. Topazes, more than a pound in weight, have been
found in Scotland.

Mr. Mawe speaks of a topaz mine at Capon, near Villa Rica, in Brazil. In
two breaks or slips of the rocks, he says, there were little soft places
where the negroes found the topazes by scraping in them with pieces of
iron. He himself observed at least a cart─load of inferior topazes, any
number of which he might have taken away; but all that he saw were
defective and full of flaws.

These stones vary much in size; some, particularly those of Siberia,
being extremely small, and others being upwards of an inch in thickness.
In the Collection of Natural History at Paris there is a Brazilian topaz
which weighs four ounces and a quarter. These stones are not
sufficiently scarce to be, in general, much valued by the jeweller or
lapidary. The deep yellow variety is preferred to the pale sort,
although the latter is often superior to it both in size and hardness.

Figures have sometimes been engraved on the topaz; and these, when well
executed, are of great value. In the National Museum at Paris there is a
superb Indian Bacchus engraven on a topaz. The cabinet of the Emperor of
Russia contains several fine topazes of this description.

Some of the coarse kinds of topaz are broken down, pounded, and used
instead of emery for the cutting of hard minerals; and powdered topaz
was formerly kept in apothecaries’ shops, and sold as an antidote
against madness.

It is a somewhat singular circumstance, that, if the Saxon topaz be
gradually exposed to a strong heat in a crucible, it will become white
and, on the contrary, that Brazilian topazes by the same process become
red or pink. By exposure to a still stronger heat, the Brazilian topaz
changes its colour to a violet─blue.

Jewellers usually divide topazes into the following kinds:

62. BRAZILIAN and SAXON, already mentioned.

63. BOHEMIAN.—These are found chiefly in the tin mines of Bohemia, are
of small size, deficient in transparency, have only grey or muddy white
colours, and are of little value.

64. BLUE TOPAZ.—This is a large Brazilian gem, which varies in size from
one or two carats to two or three ounces. A fine blue topaz, without
flaw, and which weighed an ounce and a quarter, was sold for 200
guineas. It is sometimes difficult to distinguish a blue topaz from an
aqua marine (68).

65. PINK TOPAZ.—Some beautiful rose─coloured varieties of topaz have
been brought from Asia Minor, and others are found in South America; but
the pink topazes in the jewellers’ shops are chiefly stones of the
yellow Brazilian kind, which have had their colour changed by heat.

66. The WHITE, or NOVA MINA TOPAZ, is a perfectly colourless and
transparent variety. It generally occurs of small size, and is in
considerable estimation in Brazil for ear─rings, or for being set round
yellow topazes. Small stones of this description have recently been
found at St. Michael’s Mount, in Cornwall.

There is imported from Brazil a yellow kind of crystal (83), which is so
similar, in its appearance, to the yellow topaz as sometimes to be
imposed upon purchasers for that stone.

67. _The EMERALD is a well─known gem, of pure green colour, and somewhat
harder than quartz._

_Its natural form is a short six─sided prism; but it is sometimes found
massive, and rounded like a pebble._

By the ancients the emerald was a gem much in request, and particularly
for engraving upon. They denominated it _smaragdus_, and are said to
have procured it from Ethiopia and Egypt; but, besides the true emerald,
Pliny, under this title, includes green jasper (96), malachite (231),
fluor spar (194), and some other green minerals. The pillars of emerald
in the temple of Hercules at Tyre, mentioned by Herodotus, and the large
emeralds described by Pliny as having been cut into columns and statues,
cannot be referred to the true emerald.

The deepest coloured and most valuable emeralds that we are acquainted
with are brought from Peru. They are found in clefts and veins of
granite, and other primitive rocks; sometimes grouped with the crystals
of quartz (76), felspar (110), and mica (123); and, not unfrequently,
loose in the sand of rivers. The most ancient emerald mine is that of
Manta, in Peru, but it has been some time exhausted; and most of the
emeralds that are now brought to Europe are obtained from a mine
situated in the valley of Tunca, between the mountains of New Grenada
and Popayan.

The emerald is one of the softest of the precious stones; and is almost
exclusively indebted for its value to its charming colour. The brilliant
purple of the ruby, the golden yellow of the topaz, the celestial blue
of the sapphire, are all pleasing tints; but the green of the emerald is
so lovely, that the eye, after glancing over all the others, finds
delight in resting upon this. In value it is rated next to the ruby;
and, when of good colour, is set without foil and upon a black ground,
like a brilliant diamond. Emeralds of inferior lustre are generally set
upon a green gold foil. These gems appear to greatest advantage when
table cut (Pl. II, Fig. 9), and surrounded by brilliants, the lustre of
which forms an agreeable contrast with the quiet hue of the emerald.
They are sometimes formed into pear─shaped ear─drops; but the most
valuable stones are generally set in rings. A favourite mode of setting
emeralds among the opulent inhabitants of South America is to make them
up into clusters of artificial flowers on gold stems.

The largest emerald that has been mentioned is one said to have been
possessed by the inhabitants of the valley of Manta, in Peru, at the
time when the Spaniards first arrived there. It is recorded to have been
as big as an ostrich’s egg, and to have been worshipped by the
Peruvians, under the name of the Goddess, or Mother of Emeralds. They
brought smaller ones as offerings to it, which the priests distinguished
by the appellation of daughters. Many fine emeralds are stated to have
formerly been bequeathed to different monasteries on the Continent; but
most of them are said to have been sold by the monks, and to have had
their place supplied by coloured glass imitations. These stones are
seldom seen of large size, and at the same time entirely free from
flaws.

The emerald, if heated to a certain degree, assumes a blue colour; but
it recovers its proper tint when cold. When the heat is carried much
beyond this, it melts into an opaque coloured mass.

The precious stone called oriental emerald (56) is a green and very
scarce variety of the oriental ruby.

68. _The BERYL, or AQUA MARINE, is a light or mountain green variety of
the emerald, sometimes straw─coloured, bluish, yellow, or even white._

These stones are of such frequent occurrence, even in large pieces
perfectly clear and free from flaws, they are in general so soft, and
have so little the brilliancy of other gems, that they are usually
considered of inferior value. The most beautiful kinds are brought from
Dauria, on the frontiers of China, from Siberia, and from Brazil. They
are also found in Saxony and the South of France, and are very common at
Baltimore, in North America. Specimens of aqua marine have been obtained
from the upper parts of Aberdeenshire, Scotland, where they sometimes
occur in alluvial soil, along with rock crystal and topaz. These stones
have also been found, embedded in granite, near Lough Bray, and
Cronebane, in the County of Wicklow, Ireland; and also in mountain rock,
in some parts of Devonshire.

They are cut by means of emery (58), and polished with tripoli (119).
The darkest green specimens are set upon a somewhat steel─coloured foil;
and the pale ones are either placed, like the diamond, on a black
ground, or upon a silvery foil. The aqua marine is usually made into
necklaces; but it is likewise employed for brooches, and not
unfrequently for steel stones and intaglios. The larger ones are in much
esteem among the Turks for the handles of stilettos.

69. _The TOURMALINE is a stone belonging to the same family as the
emerald, and generally of a smoky blackish colour: sometimes, however,
it is green, red, blue, or brown; and, when not very thick, it is
transparent._

_It is occasionally found in shapeless masses, but more frequently
crystallized in three, six, or nine─sided prisms, variously truncated or
terminated; and its weight is somewhat more than three times that of
water._

This stone was first made known in Europe, about the beginning of the
last century, by the Dutch merchants, who brought it from the island of
Ceylon, where it is principally found. When strongly heated it becomes
electric; one of the summits of the crystal negatively, and the other
positively. An early writer, by whom it is mentioned, says, that “it has
the property not only of attracting ashes from the warm or burning
coals, but that it also repels them again, which is very amusing: for as
soon as a small quantity of ashes leaps upon it, and appears as if
endeavouring to writhe themselves by force into the stone, they in a
little time spring from it again, as if about to make a new attempt. It
was on this account that the Dutch called it the ashes drawer.”

Since the above period, tourmaline has been found in Brazil; and in
Norway, Germany, France, and several other parts of Europe. It generally
occurs embedded in different kinds of mountain rock; and, in these, is
rather confined to single beds or strata, than disseminated through the
whole mass of the mountain. A piece of tourmaline, of cylindrical form,
and brownish grey colour, was some time ago discovered in the
neighbourhood of Kitt─hill, near Callington, Cornwall. Black tourmaline,
both in large and small crystals, is found in granite rock, in the
vicinity of the Logan, or Rocking─stones, near Treryn, in the same
county.

When laid on a table, the tourmaline appears a dark and opaque stone;
but, when held against the light, it has generally a pale brownish hue.
It is sometimes cut, polished, and worn as a gem; but, on account of the
muddiness of its colours, it is not in general much esteemed. Those
persons who wear tourmalines set in rings consider them more as objects
of curiosity than of elegance: they show them as small electrical
instruments, which, after being heated a little while by the fire, will
attract and repel light bodies.

In the superb collection of minerals of the British Museum, there is a
magnificent specimen of _red tourmaline_, or _rubellite_, which has been
valued at 1000_l._ sterling. It was presented by the King of Ava to the
late Colonel Symes, when on an embassy to that country, and was
afterwards deposited by the latter in Mr. Greville’s collection; with
that collection it became the property of the British Museum.


                             GARNET FAMILY.

70. _The PRECIOUS, or NOBLE GARNET, is a gem of crimson colour, which,
when crystallized, has the form of a twelve─sided solid (Pl II, Fig. 11,
12). It is sufficiently hard to scratch quartz, and is about four times
as heavy as water._

This stone is found abundantly in many mountains (particularly of
primitive rock), in different parts of the world. But garnets of the
hardest and best quality are brought from Bohemia, where there are
regular mines of them; and a great number of persons are there employed
in collecting, cutting, and boring them. The boring is performed by an
instrument having a diamond at its extremity, which is rapidly turned by
a bow. The work is so expeditiously performed, that an expert artist can
bore 150 garnets, or he can cut and polish thirty, in a day. In Suabia
there are two towns in which upwards of 140 persons are employed in
these operations.

In general garnets are stones of inferior value. When compared with the
ruby, those even of finest quality have a very sombre appearance. The
kinds most esteemed are such as have a clear and intense red colour, or
a rich violet or purplish tinge. The best garnets are cut in the manner
of other precious stones, and are usually set upon a foil of the same
colour. To heighten the colour and transparency of certain garnets,
jewellers either form them into what are called doublets, by attaching
to the lower part of the stone a thin plate of silver, or they hollow
them underneath.

Crystals of garnet sometimes occur three or four inches in diameter.
These are cut into small vases; which, if of good colour, and free from
defects, are highly valued. Many fine engravings have been executed on
garnet. One of the most beautiful that is known is a figure of the dog
Sirius, in the possession of Lord Duncannon.

The coarser kinds of garnet are used as emery for the polishing of other
minerals; and are thus prepared. They are made red─hot, then quenched in
water, reduced to powder in an iron mortar, and lastly diffused through
water, poured into other vessels, and allowed to settle, in order to
obtain an uniform powder. This powder is known to artists by the name of
_red emery_.

It has been conjectured that our garnet was the same kind of stone
which, on account of its colour, the ancients denominated _carbuncle_.

71. COMMON GARNET.—A very inferior variety of garnet, of brown or
greenish brown colour, is found in our own country, and particularly
amongst rocks near Huntley, in Aberdeenshire, Scotland. These garnets,
however, are, in general, so soft as to be of little value to the
lapidary; and consequently are seldom cut or polished for ornamental
purposes. But being easily fused, and abounding in iron, they are
occasionally employed as a flux in the smelting of rich iron ores: and
as an addition to poor ones.

72. SYRIAN GARNETS _are distinguished by their violet or purplish
tinge_. Some writers state that they have their name from the word
Soranus, which signifies a red stone; and others from Sirian, a town in
Pegu, where they are said to be found in great beauty.

73. PYROP GARNETS _are of a dark blood─red colour_, which, when the
stones are held between the eye and the light, falls strongly into
yellow: they are chiefly brought from Bohemia: are employed in almost
every kind of jewellery, and generally set with a gold foil. At
Waldkirch, in Suabia, there are twenty─four mills for the cutting and
polishing of pyrop garnets: and 140 masters are occupied in
manufacturing these stones.

74. VESUVIAN _is a liver─brown kind of garnet_, that was originally
found among rocks ejected from Mount Vesuvius; and in the vicinity of
which mountain it still occurs in considerable abundance. At Naples it
is cut into stones for rings and other ornaments. Vesuvian has of late
years been found in other parts of Europe; and even at Kilranelagh, and
Donegal, in Ireland.

75. CINNAMON STONE _is a kind of garnet of hyacinth─red colour_, which
is found in angular and roundish pieces among the sand of rivers in the
island of Ceylon. It is cut as a precious stone; and, when of good
colour, and free from flaws, is of considerable value.


                             QUARTZ FAMILY.

76. _COMMON QUARTZ is a hard and foliated substance, usually of white or
grey colour, and more or less transparent._

_It is generally found in shapeless masses, which are nearly thrice as
heavy as water, and the fracture of which is glassy. When crystallized,
it most commonly has the form of a six─sided prism, terminated by a
pyramid of six sides._

This kind of stone forms a constituent part of many mountains, and is
very common in our own, as well as in most other countries. It is
sufficiently hard to scratch iron and steel; and it has the property,
after having been several times successively made red─hot, and dipped
into water, of communicating to that fluid a certain degree of acidity.

Quartz is employed, in place of sand, for making the finer kinds of
glass; and also in the manufacture of porcelain. For the latter purpose
great quantities are collected from the mountains of Wales, ground into
powder, and in that state shipped to Liverpool, and other parts. After
having been burnt and reduced to powder, it is sometimes mixed with
clay, and formed into bricks for the construction of glass furnaces:
these are capable of resisting the intense heat which is requisite in
the fusion of glass.

77. BURRSTONE _is a vesicular and corroded variety of quartz, which
forms a most excellent and valuable_ _kind of millstone_. It is chiefly
found in France; but is so much esteemed by the English millers, that
the Society of Arts, in London, for many successive years, offered a
considerable reward for its discovery in Great Britain. At length a vein
of burrstone was discovered in the Moel y Golfa hills, North Wales, by a
Mr. Evans, who, in consequence received a premium from the Society.
About the same time another vein was opened near Conway; and the same
Society, in 1800, gave a premium of 100_l._ to the widow and orphan
children of the discoverer. Both these quarries were sufficiently
convenient for water carriage; yet the demand for the Cambrian burr did
not answer the expectation, and millstones of French production were
still preferred to them.

The mode of splitting these stones, as it is practised in some parts of
France, is singular, and affords a proof of the extraordinary power of
capillary attraction. The blocks are first cut into the form of
cylinders, sometimes many feet in height. To split these horizontally
into millstones, circular indentations are made round them, at proper
distances, according to the thickness that is to be given to the stones;
wedges of willow, that have been dried in an oven, are then driven into
the indentations with a mallet. When these have been sunk to a proper
depth, they are moistened with water; and, after a few hours, the
several stones that have been marked out are found to be perfectly
separated.

78. _ROCK CRYSTAL is an extremely beautiful kind of quartz, sometimes
perfectly transparent, and sometimes shaded with grey, yellow, green,
brown, or red. It occurs in the form of crystals with six sides, each
terminated by a six─sided prism._

The name of this substance was considered by the ancients to signify
ice, or water crystallized; and they imagined that crystal was produced
from a congelation of water.

Its uses are numerous. It is cut into vases, lustres, and snuff─boxes;
and many kinds of toys of extremely beautiful appearance are made of it.
When pure and perfectly transparent, it is much in request by opticians,
who make of it those glasses for spectacles which are called _pebbles_,
and who use it for various kinds of optical instruments. The best
crystal is imported from Brazil and Madagascar, in blocks, not
unfrequently from fifty to a hundred pounds in weight.

This stone is wrought into the different shapes that are required, by
sawing, splitting, and grinding. The sawing is effected by an extended
copper wire fixed to a bow: the wire is coated with a mixture of oil and
emery, and is drawn backward and forward until the operation is
performed. But, as this process is a tedious one, particularly when the
mass is large, a more expeditious, although less certain, method is
sometimes adopted. The crystal is heated red hot, and a wet cord is
drawn across, in the direction that the workman intends to split it. By
the rapid cooling thus effected, in the direction of the cord, the stone
easily splits by a single blow of the hammer, and generally in the
direction required. The grinding is performed by means of emery: and the
polishing effected by tin ashes and tripoli.

The ancients held vases that were made of this stone in great
estimation, particularly when they were of large size. Of two cups which
the tyrant Nero broke into pieces in a fit of despair, when informed of
the revolt that caused his destruction, one was estimated to be worth
more than 600_l._ of our money. The most valuable kind of crystal that
was known to the ancients was obtained from the island of Cyprus; but it
was often faulty in particular parts, having flaws, cracks, and
blemishes. When the crystal was used for the engraving of intaglios and
cameos, the artist could sometimes conceal these defects amongst the
strokes of his work; but, when it was to be formed into cups or vases,
this could not be done, and for the latter purpose the purest pieces
only could be employed.

In the counties of Cornwall and Derby, in the neighbourhood of Bristol,
and amongst the mountains of North Wales, small crystals of this kind
are frequently found: these are respectively called _Cornish_, _Buxton_,
_Bristol_, and _Snowdon_ diamonds. We are informed that the crevices of
some parts of Mont Blanc and the Alps contain rock crystal in such
abundance as to be perfectly bristled with it.

Some crystals contain in their substance drops of water, or other kind
of fluid; and these, as curiosities, are usually sold at a rate
considerably higher than others. There are in the British Museum
specimens of crystal which enclose many kinds of foreign substances,
such as ironstone, needle antimony, and asbestos (136).

Various means have been devised for communicating colours to rock
crystal. If it be heated and plunged into a solution of indigo, or
copper, it acquires a blue colour; or if into a decoction of cochineal,
a red colour. A clove─brown colour may be given by exposing it to the
vapour of burning wood. Artists sometimes communicate beautiful colours
to rock crystals, by forming them into what are called _doublets_. Two
modes of doing this are adopted. In one, a stone that is brilliant─cut
at the top is hollowed underneath, filled with the colour that the stone
is intended to exhibit, and then closed at the bottom by a plate of
glass. If this kind of doublet be dexterously executed, the deception is
not easily discovered; for the whole mass will appear of an uniform
tint. The second kind of doublet is formed by cementing a coloured plate
of glass on the base of a rose or brilliant─cut crystal: by this the
whole stone acquires the colour of the plate.

There are found in nature, many coloured kinds of crystal. These are
often confounded with precious stones; and, as such, are made into
female ornaments of different kinds. The following are the principal of
them.

79. COMMON AMETHYST.—_This is a violet─coloured crystal_, which acquires
considerable brilliancy in polishing, and is sometimes of sufficient
size to be formed into columns more than a foot in height, and several
inches in diameter. When the colour is good, and uniformly diffused,
amethysts are cut into necklaces, bracelets, ear─rings, and seals; and,
when less pure, they are manufactured into snuff─boxes. They are valued
in proportion to the depth of their colour, and to their perfect
transparency. The most favourite form in which they are made up is in
necklaces; and as it is not easy to find a number of perfect stones with
precisely the same tint of colour, necklaces of this description are
very valuable. The finest that is known was in the possession of her
late Majesty. When the colour is not uniformly diffused, jewellers
sometimes expose amethysts, for a little while, in a mixture of sand and
iron─filings, to a moderate heat; and, by this process, their appearance
is rendered more uniform.

The amethyst being almost the only coloured stone that can be worn with
mourning, it derives, from this circumstance, a considerable addition of
value.

This species of gem was well known to the ancient Greeks and Romans, and
was held by them in great esteem. Its name is derived from the Greek
language, and implies a power of preventing intoxication; which
(originating no doubt in the resemblance of its colour to that of wine,
and the absurd doctrine of sympathies) it was believed by the ancients
to possess. They ascribed to it many other virtues, equally surprising
and equally absurd; particularly that the wearing of it would expel
melancholy, procure the confidence and friendship of princes, render
people happy, and even dispel storms of wind and hail. The ancients
frequently engraved upon amethyst; and their favourite subject was the
representation of Bacchus and his followers.

The most valuable amethysts are imported into Europe from India and
Ceylon. These, although they are with truth denominated oriental, must
be carefully distinguished from the true oriental amethyst (55), which
is a much more valuable gem. The amethysts next in esteem are found in
Brazil, and are procured in the mining districts of that country.
Siberia, and various countries in Europe, especially Germany and Spain,
also furnish very beautiful amethysts; and inferior stones of this
description are even found in the mountainous districts of some parts
both of Scotland and Ireland.

80. FALSE RUBY _is a crystal of red colour_, and found in Bohemia,
Silesia, and Barbary.

81. FALSE, _or_ WATER SAPPHIRE _is a blue crystal_, which does not
differ much in appearance from the true sapphire, but is considerably
less hard. This kind is found in Bohemia, Silesia, and some parts of
Switzerland, but it is not so valuable as the last.

82. FALSE EMERALD _is a green variety of crystal_, the scarcest and most
valuable of all the coloured kinds. It is chiefly found in Saxony and
Dauphiny.

83. YELLOW, _or_ TOPAZINE CRYSTAL _is a stone of wine─yellow colour_. It
is found in Brazil and Bohemia, but has no other alliance with the true
topaz than its colour.

84. CAIRN GORUM CRYSTALS are obtained in various parts of Scotland, but
particularly from a mountain of that name in the county of Aberdeen.
_They are usually of smoky yellow or brown colour_, and are, at this
time, so much in request for ornamental articles of dress, that several
lapidaries have been induced to settle in Aberdeen, who are constantly
employed in cutting them for seals, rings, necklaces, brooches, and
other trinkets. When these crystals are of deep and good colour, they
are nearly as estimable as topazes; and, if clear and large, they are
sold at a high rate. The price of inferior seal─stones varies from ten
shillings to three or four pounds each; but those of superior beauty
will produce from five to ten guineas. Such specimens as have a pure and
full yellow colour are often sold for topazes. When they are muddy, the
lapidaries have the art of entirely dissipating the colour, and giving
them a transparent lustre. This is done by means of heat, which will
dissipate the colour of every species of crystal.

85. _AVANTURINE is a quartz, generally of reddish colour, sprinkled with
yellowish shining points of mica (123), which are dispersed through its
whole substance._

A French artist, some years ago, having by accident, or “par aventure,”
suffered a quantity of brass filings to fall into a vessel of melted
glass, afterwards found that it was admirably calculated for vases and
different kinds of ornamental work. Hence he denominated it avanturine,
a name which mineralogists have since applied to those natural objects
of which this production of art was an apparent imitation.

Avanturine is found in some of the countries bordering upon the White
Sea, in Spain, and some parts of France. In the late Leverian Museum
there was a piece which weighed near five pounds, and was unique both
for beauty and magnitude. It had been discovered in 1788, amongst the
ruins of the triumphal arch of Julius Cæsar in the valley of Suse, in
Piedmont; and was purchased of the person who found it for 200 guineas.
Avanturine is cut into various ornamental articles, which are sometimes
sold at a very high price.

Imitations of it are very common, and are formed by the simple operation
of throwing brass or copper filings into coloured glass in a state of
fusion.

86. _CATS─EYE is a stone of brownish grey colour, tinged with green,
yellow, white, or red; semi─transparent, and reflecting from its
interior a splendid white line or speck, which_ _varies according to the
direction in which the stone is held to the light._

_It is found in pieces that are rounded, massive, or blunt─edged._

These stones are considered by some writers as varieties of quartz (76),
and by others as a kind of opal (102). They are sometimes found in
Hanover, but are chiefly brought from the island of Ceylon. It is usual
to cut them before they are exported, and generally in a convex and
oblong form, without facets, and in such manner as to bring the streak
which intersects them into the centre. Among the king of Candy’s jewels,
which were sold by auction in London, in June 1820, was a cat’s─eye of
extraordinary magnitude and beauty. It was two inches in diameter, of
dark colour, and nearly hemispherical. This stone was set in gold, with
small rubies round it, and was sold for more than 400_l._

Cat’s─eyes are chiefly used for setting in rings. Their size seldom
exceeds that of a hazel nut; but there was one in the cabinet of the
Dukes of Tuscany, which was nearly an inch in diameter. Those that are
the most highly esteemed are of an olive─green, or red colour.

87. _WOODSTONE is a very hard mineral substance, supposed to have been
wood petrified with a siliceous mineral called hornstone._

_It is of various colours; and has not only the external appearance, but
the internal organization of wood._

This extraordinary mineral is found embedded in sandy loam, in alluvial
soil (269), and occurs in various parts both of Europe and Asia. It has
been found in ferruginous sand, near Woburn, in Bedfordshire, and near
Nutfield, in Surrey. Immense pieces of it are discovered in some places
in the original shape of the trees; trunks, branches, and roots. In the
year 1752 the whole under part of the trunk of a tree, with its branches
and roots, was found, in a state of woodstone, near Chemnitz, in Saxony;
and, in the Electoral Cabinet at Dresden, there is part of the trunk of
a tree, from the same place, which measures five feet in length and as
many in thickness.

Woodstone is in considerable request by lapidaries. It takes a good
polish, and is made into beads for necklaces, and other female
ornaments. In the East Indies it is generally called _Petrified Tamarind
Tree_.

88. _COMMON SAND is a granulated kind of quartz; or consists of rounded
grains of small size, which have a vitreous or glassy surface._

_It is usually of white or yellowish colour; but is sometimes blue,
violet, or black._

In the torrid regions of Africa and Asia there are immense tracts of
desert covered only with sand, so dry and light as to be moveable before
the wind, and to be formed into vast hills and boundless plains. These
are incessantly changing their place, and frequently overwhelm and
destroy the travellers whose necessities require them to enter these
dreary realms.

Sand has numerous uses. When mixed in due proportion with lime, it forms
that hard and valuable cement called mortar. Melted with soda (200) and
potash (205) it is formed into glass; white sand being used for the
finer kinds, and coarse and more impure sand for bottle glass. A very
pure kind of sand which is found in Alum Bay, on the west side of the
Isle of Wight, and on some parts of the coasts of Norfolk, is in great
request by glass─makers. Sand is also employed in the manufacture of
earthenware; and its utility in various branches of domestic economy,
but particularly for the scouring and cleaning of kitchen utensils, is
well known. In agriculture sand is used by way of manure, to all soils
of clayey lands: as it renders the soil more loose and open than it
would otherwise be. The best sand for this purpose is that which is
washed by rains from roads or hills, or that which is taken from the
beds of rivers.

There is a kind of sand which is naturally mixed with clay, and has the
name of _Founder’s Sand_, from its being chiefly employed in the
formation of moulds to cast metals in. At Neuilly, in France, there is a
bed of perfectly transparent and crystalline sand. Each grain, when
examined with a magnifying glass, is seen to consist of a perfect
six─sided prism, terminated by two six─sided pyramids.

The uses of the different kinds of _Sandstone_ will be enumerated in the
account of the rocks (267, 268).

89. _LYDIAN STONE is a kind of flinty─slate, of greyish or velvet─black
colour, not quite so hard as flint, opaque, and about twice and a half
as heavy as water._

_It is usually massive, and, internally, has a glimmering appearance._

This mineral occurs in beds in primitive clay─slate (257); and is found
in Bohemia and Saxony, and also in the Pentland hills near Edinburgh. It
was first noticed in Lydia, whence it derived its name.

It is sometimes used as a touchstone to ascertain the purity of gold and
silver. This was its use among the ancients. The metal to be examined is
drawn along the stone so as to leave a mark, and its purity is judged by
the colour of the metallic streak. A good touchstone should be harder
than the metals, or metallic compounds to be examined; if softer, the
powder of the stone mixes with the trace of the metal and obscures it. A
certain degree of roughness on the surface of the best stone is also
requisite, that the metal to be tried may leave a trace or streak
sufficiently distinct. It must not, however, be too rough, otherwise the
particles of the metal will be hid amongst its inequalities, and no
distinct trace will be formed. The touchstone should also be of black
colour, as this tint shows the colour of the streak better than any
other.

90. _FLINT is a peculiarly hard and compact kind of stone, generally of
smoke─grey colour, passing into greyish white, reddish, or brown. It is
nearly thrice as heavy as water, and when broken will split, in every
direction, into pieces which have a smooth surface._

_It is very common in several parts of England, generally among chalk,
arranged in a kind of strata or beds, and in pieces that are for the
most part either rounded or tubercular._

The property which flint possesses of yielding sparks, when struck
against steel, has rendered it an article of indispensable utility in
the system of modern warfare. To this substance the sportsman also is
indebted for a means of obtaining his game. The art of cutting, or
rather of breaking, this stone into gun─flints is of modern date, and
was for a long time kept secret. The most absurd and contradictory
accounts have been given of it by various writers; and it is only of
late that the true mode has been rendered public. It consists in
striking the stone repeatedly with a kind of mallet, and bringing off at
each stroke a splinter which is sharp at one end and thick at the other.
These splinters are afterwards shaped, by placing them upon a sharp iron
instrument, and then giving them repeatedly small blows with a mallet.
During the whole operation the workman holds the stone in his hand, or
merely supports it on his knee: and the operation is so simple, that a
good workman has no difficulty in making 1500 flints in a day. The
manufacture of gun─flints is chiefly confined to England, and two or
three departments in France. In Prussia an attempt was once made to
substitute a kind of earthenware or porcelain for flint; and such was,
for some time, used by the Prussian soldiers. All the kinds of flint are
not equally adapted for guns: the best are the yellowish grey; the dark
smoke and ash─grey varieties are also used, but they are neither so easy
to be split, nor do they afford such thin fragments as the other; and,
owing to their greater hardness, they wear the lock sooner.

Flint is employed in the manufacture of porcelain and glass. For this
purpose it is heated red hot, and, in that state, is thrown into cold
water. It is then of a white colour, and capable, without difficulty, of
being reduced to powder, either in a mortar or by a mill. After this
powder has been passed through fine sieves, some aqua fortis is poured
upon it, to dissolve any particles of iron which it may have acquired in
the grinding. The powder is then several times washed in hot water, and
afterwards dried for use. The glass that is manufactured from this
substance is perfectly transparent and faultless.

_Glass_ is made by mixing sand, or prepared flint, with a certain
proportion of soda (200) or potash (205); and exposing these substances,
in a furnace, to a violent heat. When they are in a perfectly fluid
state, part of the melted matter is taken out at the end of a long
hollow tube. This is done by dipping the tube into it, and turning it
about until a sufficient quantity is taken up; the workman, at each
turn, rolling it gently upon a piece of iron, to unite it more
intimately. He then blows through the tube till the melted mass, at the
extremity, swells like a bubble; after which he rolls it again on a
smooth surface to polish it, and repeats the blowing until the glass is
brought as nearly to the size and form of the vessel required, as he
thinks necessary.

If he be forming a common bottle, the melted matter at the end of the
tube is put into a mould of the exact size and shape of the body of a
bottle; and the neck is formed by drawing out the ductile glass at the
upper extremity.

If he be making a vessel with a large or wide orifice, the glass, in its
melted state, is opened and widened with an iron tool; after which,
being again heated, it is whirled about with a circular motion, and, by
the centrifugal force thus produced, is extended to the size required.
Should a handle, foot, or any thing of similar kind be required, that is
made separately, and stuck on in its melted state.

_Window glass_ is made in a similar manner, except that the mass at the
end of a tube is formed into a cylindrical shape. This being cut
longitudinally by scissars or shears, is gradually bent back until it
becomes a flat plate.

Large _plate glass_ for looking─glasses is made by suffering the mass,
in a state of complete fusion, to flow upon a casting table, with iron
ledges. These confine the melted matter, and, as it cools, a metallic
roller is passed over it, to reduce it to an uniform thickness.

Glass utensils, unless very small and thin, require to be gradually
cooled in an oven. This operation is called _annealing_, and is
necessary in order to prevent them from cracking by change of
temperature, wiping, or slight accidental scratches.

It appears that the manufacture of glass was known very early; but glass
perfectly transparent was esteemed of extremely high value. It is stated
that the Emperor Nero purchased two glass cups with handles for a sum
which was equivalent to 50,000_l._ of our money. The windows of some of
the houses of the ancient city of Pompeii, which was buried by an
eruption of Mount Vesuvius, in the year 79, were glazed, but the glass
was thick, and not transparent.

By many persons flint is used as a test for ascertaining the purity of
silver coins. This is done by rubbing them upon the flint; and if the
mark which they leave be not perfectly white, they are rejected as
counterfeit.

91. _CALCEDONY is a species of quartz, generally of whitish, bluish, or
smoke─grey colour; and, when broken, it appears internally dull, and
somewhat splintery._

_It is generally found in a massive state, is harder than flint,
generally semi─transparent, and 2½ times heavier than water._

The name of this stone is derived from Chalcedon, in Upper Asia, whence
it appears to have been originally obtained, and where it is still found
in considerable abundance. Several superb specimens of calcedony have
been found in Britain, and particularly in some of the tin and copper
mines of Cornwall. It occurs in several parts of Scotland; and in many
of the countries of the Continent. In the Leverian Museum there was a
specimen of calcedony, which weighed more than 200 pounds. Its whole
surface appeared such that, at first sight, one might imagine it to have
formerly been in a liquid state: it had much the appearance that thick
oil has while boiling.

Few stones are susceptible of a higher or more beautiful polish than
calcedony. Hence the different varieties of it are cut into ring and
seal stones, necklaces, ear─pendants, small vases, cups, and
snuff─boxes.

92. _ONYX is a kind of calcedony, generally marked alternately with
stripes of white and black, or white and brown._

Its name is derived from the Greek language, and has been given on
account of its resemblance in colour to the whitish band at the base of
the human nail. The distinction which appears to be made betwixt onyx
and _sardonyx_, arises from the colours of the former being arranged
either concentrically, or in a somewhat confused manner, and those of
the latter in regular stripes or bands.

Both these kinds are highly esteemed by lapidaries, for the formation of
vases, snuff boxes, and trinkets of various kinds. Of sardonyx the
ancients made those beautiful cameos, many of which still ornament our
cabinets. The ingenuity they have shown, in the accommodation of the
natural veins and marks of the stone to the figures engraven upon them,
is such as to excite, in many instances, the greatest admiration.

It is said that we are entirely ignorant of the country whence the
ancient artists obtained the large specimens of sardonyx which are now
found in some cabinets.

Onyx is imported from the East Indies, Siberia, Germany, and Portugal.

93. _CARNELIAN is another kind of calcedony usually of a red or flesh
colour, though sometimes white, orange, or yellow._

On several of the British shores carnelians are found with other
pebbles: but the most beautiful and valuable kinds are imported from the
East Indies. These are sometimes so large as to measure nearly three
inches in diameter. The kinds principally in request are those of pure
white, and bright red colour; and jewellers have the art of changing the
colour of the yellow varieties to red, by heat.

No stone is so much in request for seals as carnelian. It is likewise
cut into beads for necklaces, and stones for ear─rings; into crosses,
bracelets, and other trinkets, which, in India, form a considerable
branch of traffic. The amount of the sale value of different kinds of
carnelian goods vended by the East India Company in 1807, was
11,187_l._: but, in other years, it has not usually been so much as half
that sum.

Formerly carnelians were exported from Japan to Holland; and thence were
carried to Oberstein, in France, to be exchanged for the agates of that
country, which were exported to China.

The carnelian was much esteemed by the ancients; and many fine engraved
carnelians are preserved in different collections.

94. _CHRYSOPRASE, an extremely hard kind of stone, of clear and delicate
apple─green colour, is considered to be a kind of calcedony._

This beautiful mineral has hitherto been found only in the vicinity of
Kosemitz, and in a few other parts of Lower Silesia. It is susceptible
of a high polish, and is much prized by jewellers when its colour is
deep and pure. Its colour, however, is so fugitive, that, if kept in a
warm and dry situation, it loses the greatest part of it; and if exposed
to moisture it becomes much altered. Lapidaries assert, that great care
ought to be taken in the polishing of it;—pretending that if, from want
of sufficient moisture, or by the too rapid motion of the wheel, it be
over─heated, it will become whitish or turbid.

Chrysoprase is generally cut into a convex form, or what jewellers call
_en cabochon_; and is set with green taffeta beneath it, as foil. It is
used for ring stones, brooches, and other ornaments; and is found to
harmonize well with diamonds and pearls. The larger and more impure
masses are cut into snuff─boxes, seal stones, and similar articles. Some
of the finest specimens of chrysoprase that are known, are to be seen in
the cathedral church of Prague, where a small closet is inlaid with
them.

Imitations of chrysoprase are sometimes imposed upon the public; but
these are easily known by persons who are acquainted with the nature of
precious stones.

95. _BLOODSTONE, or HELIOTROPE, is an opaque stone of the quartz family,
generally of dark green colour, with a somewhat bluish cast, and marked
with blood─red spots or stripes._

_It usually occurs in masses of irregular form; and, when cut thin, is
sometimes translucent at the edges._

The most valuable kinds of bloodstone are imported from the East. They
are not so opaque as those which are found in Germany, and are marked
with more vivid spots. As bloodstone is capable of a high polish, and is
even better calculated for engraving upon than carnelian (93), it is in
great request for seal stones, for the tops and bottoms of snuff─boxes,
and other articles on which costly gold mountings are frequently
bestowed. Its dark colour and opaque appearance prevent its being much
used for beads. Great quantities of it are consumed in China as
ornaments to the girdle clasps of the superior ranks of people. Absurd
as it may appear, many persons entertain a notion that this stone worn
in the dress will prevent bleeding at the nose. Good bloodstone and
carnelian are considered to be about the same value.

There are many cameos and intaglios, both by ancients and moderns,
executed in bloodstone. In the National Library at Paris, there is a
fine engraved stone of this kind, representing the head of Christ whilst
undergoing the punishment of scourging, and so cut that the red spots
are made to represent drops of blood.

The ancients procured bloodstones chiefly from Ethiopia; but, at
present, the most highly esteemed varieties are brought from Bucharia,
Great Tartary, and Siberia. A kind of mineral nearly resembling this is
found in Rum, one of the western isles of Scotland.

The spots in bloodstone are particles of red jasper.

96. _JASPER is a species of quartz, and one of the hardest stones with
which we are acquainted. It varies much in colour, being red, green,
yellow, blue, olive, violet, black, and often variegated, spotted, or
veined with several other colours. It is usually opaque, but is capable
of receiving a beautiful polish._

_This stone is found in large and shapeless masses, and constitutes an
ingredient in mountains of various parts of the world._

Such is the hardness of jasper, that the savages of Canada avail
themselves of it for the fabrication of the heads of javelins, and
sometimes also of arrows. It is used by artists for the formation of
vases, snuff─boxes, seals, and trinkets of various kinds; and formerly
cups and saucers were sometimes made of it. Many beautiful antique
engravings have been made upon jasper.

In the province of Andalusia, in Spain, there are four fine quarries of
jasper. One of these is celebrated for a blood─red stone, streaked with
white, exceedingly hard and very handsome, of which the beautiful
columns of the tabernacle in the Escurial are made. This quarry is in
the territory of Cogullus, in the archbishopric of Seville, and was
purchased by the Crown in 1581; but was afterwards so far neglected that
even the place where it lay was not remembered. It was, however, again
discovered about the end of the reign of Charles the Third, after a very
expensive search made by order of the government.

Jasper occurs in the Pentland hills, near Edinburgh, and in several
other parts of Scotland; in the Shetland Islands, and Hebrides. It has
been observed in most of the countries of the Continent; and is found,
in great abundance, in Siberia.

97. RED JASPER _is an opaque red stone which is found embedded in red
clay─ironstone in Baden_; and is cut and polished for various ornamental
purposes. There are extant many fine antique engravings on red jasper.

98. EGYPTIAN PEBBLE _is a kind of jasper, that is found in globular or
rounded pieces, and is distinguishable when cut or broken, by its
numerous colours, arranged in concentric stripes or layers_. It is
chiefly brought from Egypt; and, as it is capable of receiving a fine
polish, and when polished is very beautiful, it is manufactured into
several kinds of ornamental articles. From the great abundance in which
it is supplied, it is, however, much less valuable than carnelian (93).
The colours of the Egyptian pebble frequently assume very singular
forms. There was one in the Leverian Museum which exhibited, in the
centre, the resemblance of a pantaloon, or a man wearing a fool’s cap.

99. STRIPED, or RIBBON JASPER, _is marked with alternate stripes of
different colours_; and is found in Siberia, Saxony, and even in the
Pentland hills, near Edinburgh. It receives an excellent polish, and is
frequently cut into the tops and bottoms of snuff─boxes. The red and
green layers of jasper, being well defined and regular, this kind is
used for several purposes of ornament, particularly for cameos.

100. _AGATE, or AGATE JASPER, as some mineralogists denominate it, is a
semi─transparent stone of the quartz family, which is capable of
receiving a high and very beautiful polish._

_These stones are always found in a shapeless or massive form, and
nearly of all colours, except bright red and green._

The name of agate is derived from the river Achates, in Sicily, in the
vicinity of which these stones were obtained by the ancients in great
abundance. They are now found in several parts of Scotland; in Iceland,
Saxony, and Hungary; and they are occasionally brought into Europe from
China and the East Indies.

Agates are used in several kinds of ornamental work, and particularly
for necklaces and seals. They are occasionally made into cups, the
handles of knives and forks, hilts of swords and hangers, and the tops
and bottoms of snuff─boxes. The less ornamental kinds are manufactured
into small mortars, which are employed by enamellers and others, for
pounding such substances as are too hard to be reduced in any other way.
They are also made into instruments for grinding colours, and into
polishers for the glazing of linen. In the Electoral Cabinet at Dresden,
and the Ducal Cabinet in Brunswick, there are several elegant vases
formed of agate.

The most beautiful agates which our island produces are known by the
name of _Scots Pebbles_. These are found in various parts of Scotland,
but principally on the sea─shore, in the neighbourhood of Dunbar. _Agate
pebbles_ are found on several of the English shores, as those of
Suffolk, Dorset, Scotland, Wales, and Ireland; and sometimes even in
gravel pits. Many of them will bear cutting and polishing as well as the
best agates of foreign countries.

Agates are occasionally seen to be figured in very singular manner; but
this, in some instances at least, is suspected to be the work of art.
One is mentioned in the church of St. Mark, at Venice, which had the
representation of a king’s head surmounted by a diadem. On another, was
represented a man in the attitude of running. But the most remarkable of
all seems to have been one which contained a representation of the nine
Muses, with Apollo in the midst of them!

It must be remarked that agate is not, as some mineralogists imagine, a
simple mineral, but that it is composed of various species of the quartz
family, intimately blended together. It consists chiefly of calcedony
(91), with flint, hornstone, carnelian (93), jasper (96), cacholong
(105), amethyst (79), and quartz (76). Of these minerals sometimes only
two, and sometimes three or more, occur in the same agate. Its
varieties, consequently, are extremely numerous.

101. MOCHOA STONE _is a kind of agate, which has on its surface the
resemblance of moss_; and this so nearly approaching a natural
appearance, that some persons have actually supposed it to be occasioned
by a condensation of moss into stone. Its name is derived from _mocks_,
the German word for moss.

These stones are used for several ornamental purposes; and are not
unfrequently imitated, by spreading a solution of copper in nitric acid
or aqua fortis (30) over the surface of a plain agate, and then setting
a small iron nail on its head in the middle. The acid unites with the
iron, and deposits the copper in beautiful ramifications from the
centre. The nail must then be removed, and the surface carefully washed
by dipping the stone into warm water. Afterwards, on the application of
a moderate heat, the copper becomes black. As, however, the deposition
is merely superficial, it requires to be covered with glass, to preserve
it from injury.

102. _OPALS are a semi─transparent kind of stones, which have a milky
cast, and, when held betwixt the eye and the light, exhibit a changeable
appearance of colour._

_They are always found in a shapeless or massive state, are brittle, and
considerably less hard than most other precious stones._

The only opal mines in the world are those of Hungary. About four
centuries ago, opals were obtained, in such abundance, from these mines,
that upwards of three hundred persons were employed in them. They still
produce opals, some of which are so valuable as to pass, in commerce,
under the appellation of _oriental opals_, whilst others are so poor as
to be of no value whatever to the jeweller. Opals are also found in
other parts of Europe; and in the island of Sumatra and several parts of
the East Indies.

Few precious stones are more beautiful than opals. Their elegant play of
colours, brilliant blue, green, red, and yellow, variously modified, has
procured for them a distinguished rank among gems. Notwithstanding this,
they are but ill suited to the purposes of jewellery, on account of
their softness, their great frangibility, and their sometimes splitting
on a sudden change of temperature. They are usually set without bottoms;
but sometimes with a black bottom, and sometimes with a foil of red,
blue, or gold colour. Their value is such that a fine oriental opal is
considered worth about twice as much as an oriental sapphire of the same
size. By the Turks they are so peculiarly esteemed, that a fine opal of
moderate size has sometimes been sold at the price of a diamond. The
esteem in which they were held among the ancient Romans was such, that
Nonius, the Roman senator, is stated to have preferred banishment to
parting with a favourite opal which Mark Antony was anxious to possess.

In the abbey of St. Denys, near Paris, there was formerly a curious
ancient opal which was green on the outside, and, when viewed against
the light, exhibited a fine ruby colour: and in the Imperial Cabinet at
Vienna, there are two pieces of opal, from the mines in Hungary, one of
which is about five inches long, and 2½ inches broad; and the other the
size and shape of a hen’s egg. Both these stones exhibit a very rich and
splendid play of colours.

In the purchasing of opals great caution is requisite, as fine glass
pastes have not unfrequently been substituted for them, and sold at
enormous prices.

103. HYDROPHANOUS OPAL, _or_ OCULUS MUNDI, _is a kind of opal, the
distinguishing characteristic of which is, that it gradually becomes
transparent, and exhibits a beautiful play of colour after being
immersed in water_. It is either of a whitish brown, yellowish green,
milky grey, or yellow colour, and opaque; and, when touched by the
tongue, adheres to it.

The name of oculus mundi has been given to these stones from an internal
luminous spot, which changes its position according to the direction in
which they are held to the light. The countries in which they are
chiefly found are Hungary and Iceland.

They are sometimes set in rings; and the prices at which they were
formerly valued were, in the highest degree, unaccountable and absurd.
At present their value is considerably lower, though they are still in
great request as objects of curiosity. The phenomenon of their becoming
transparent in water is supposed to be occasioned by that fluid soaking
through their whole substance, in the same manner as the transparency of
paper is occasioned by immersing it in oil. An hydrophanous opal
weighing 27½ grains was kept four minutes in water, and, on being taken
out, weighed 32½ grains, having received in this short period an
augmentation of five grains, or more than one sixth part of its whole
weight. When taken from the water, these stones as they dry become again
opaque.

To preserve them in beauty and perfection, care should be taken not to
immerse them in any but pure water, and to take them out as soon as they
have acquired their full transparency. If these precautions be
neglected, the pores will soon become filled with earthy particles: the
stones will cease to exhibit their peculiar property, and will ever
afterwards continue opaque.

104. COMMON OPAL _is a semi─transparent kind of opal, which does not
exhibit any changeable refraction of colour_. It is found in Germany,
France, Italy, and other countries of the Continent, and is employed for
brooches and other ornaments. A green─coloured Saxon variety is
sometimes cut into ring─stones.

105. MOTHER─OF─PEARL OPAL, _or_ CACHOLONG, _is a milk─white, yellowish,
or greyish─white kind of opal_, which occurs in Iceland, Greenland,
Spain, and the island of Elba. It is sometimes cut into a concave form,
for brooches, and other female ornaments. Italian artists also use it
for mosaic work.

106. WOOD OPAL _appears to be wood that, by some extraordinary operation
of nature, has been converted into opal_. Some specimens exhibit, very
beautifully, the ligneous texture. This kind of opal is chiefly cut into
plates for the tops and bottoms of snuff─boxes. It is found in alluvial
land in some parts of Germany and Hungary. Several years ago the trunk
of a tree, penetrated with opal, and so heavy that eight oxen were
requisite to draw it, was found in Hungary.


                           PITCHSTONE FAMILY.

107. _OBSIDIAN is a kind of glass, generally of blackish colour, formed
in volcanoes, from which it issues in thick streams._

This substance has been used for various purposes. It is possible to cut
and polish it; but its brittleness and frangibility are so great, that,
without much care, it will fly into pieces during the working. The
reflectors of telescopes are sometimes formed of it. In Mexico and Peru
obsidian is cut into mirrors; and the inhabitants of those countries
used formerly to manufacture it into knives and other cutting
instruments. Hernandez says that he saw more than a hundred of these
knives made in an hour. Cortez, in a letter to the Emperor Charles the
Fifth, relates that he saw razors that had been formed of obsidian. The
natives of Easter and Ascension Islands use this substance for cutting
instruments; and also for pointing their lances and spears, and, in
place of flint, for striking fire with. According to the account that
has been given by Pliny, the ancients sometimes formed obsidian into
mirrors, and ornamental articles of different kinds. The Danish
lapidaries, who obtain considerable quantities of it from Iceland, cut
it into snuff─boxes, ring─stones, and ear─pendants.

Obsidian is found near Mount Hecla, and in other parts of Iceland. Sir
George Mackenzie, during his journey through that island, observed an
immense mass of this substance, which appeared to him to have been part
of a stream that had flowed from a volcano. It is also found in Sicily,
and several other islands of the Mediterranean; and in nearly all parts
of the world where there are volcanoes.

108. _PUMICE is an extremely light and porous mineral, of somewhat
fibrous texture, and of white, grey, reddish, brown, or black colour._

From the texture of this mineral, which is chiefly brought from the
neighbourhood of volcanoes, some persons have imagined it to be asbestos
decomposed by the action of fire. Its lightness is such that, placed in
water, it will float.

To mechanics and other artists pumice stone is a very useful mineral. It
is employed for cleansing and smoothing the surface of wood, leather,
metal, stones, glass, and other substances; and it is used by
parchment─makers, curriers, and hat─makers. Hence it forms a
considerable article of trade: and is exported from the Lipari Islands,
in great quantities, to the different countries of Europe. Sailors in
the Mediterranean rub their beards off with pumice, instead of shaving.
On account of its porosity, it is used in Teneriffe as a filtering
stone. It forms a pernicious ingredient in some kinds of tooth powder;
and in Italy is ground and used instead of sand, in the making of
mortar. Pumice occurs in Ireland, along with obsidian (107); and it
abounds in several islands of the Grecian Archipelago.


                          AZURE STONE FAMILY.

109. _LAPIS LAZULI, AZURE STONE, or LAZULITE, is a mineral of azure─blue
colour in various shades, and generally accompanied with white or
clouded spots, and also with pyrites (236), which have the appearance of
golden veins or spots. Its texture is earthy, and fracture uneven. It is
opaque, or nearly so, and, in some parts, is sufficiently hard to strike
fire with steel. We are not informed that lapis lazuli is otherwise
found than in shapeless masses or lumps._

About fifty years ago this stone was an article much in fashion for
various ornamental parts of dress. Being capable of very high polish, it
was cut into beads, stones for rings, bracelets, and necklaces. It was
also cut into ornamental vases, small statues, and the tops and bottoms
of snuff─boxes; but of late it has been almost wholly out of use for
these purposes. Before the French Revolution it was imported, to
considerable extent, into that country from the Persian Gulf for the
inlaying of richly─decorated altars; and its value was appreciated
according to the proportion of its yellow spots or veins: these, by many
persons, were erroneously considered to be of gold.

The most important purpose to which lapis lazuli is now applied is in
the manufacturing of the beautiful and brilliant blue colour so much
esteemed by painters, called _ultramarine_. For the making of this, such
pieces are selected as contain the greatest proportion of blue
substance, and consequently the least yellow or white. These are burned
or calcined, reduced to a fine powder, made into a paste with wax,
linseed oil, and resinous matters of different kinds, and afterwards
separated by washing. The powder that is left in this operation, which
requires much time and great attention to perform, is ultramarine.

There are few colours so little susceptible of change from the effects
of time as ultramarine: the consequence of this has been that, as
several of the ancient painters introduced it for the representation of
blue drapery, their pictures, in many instances, are now devoid of
harmony, as this colour alone has stood, whilst all the others have
changed.

Lapis lazuli is principally brought from Persia, Natolia, and China; but
it is also found in Siberia and Tartary. In Europe it has been
discovered only in Germany, and among the ruins of Rome.

A coarse imitation of it is sometimes made by throwing copper filings
into blue enamel whilst in a melted state.


                            FELSPAR FAMILY.

110. _COMMON FELSPAR is a hard kind of stone which varies much in
colour, being flesh─red, bluish grey, yellowish white, milk─white, or
brownish yellow._

_It is found in a massive state, disseminated or crystallized in four,
six, and ten─sided prisms; will strike fire with steel, and is sometimes
opaque and coloured, sometimes transparent and whitish._

The name of felspar is derived from the German language, and signifies
_spar of the fields_. It is a very common substance, and constitutes a
principal part of many of the highest mountains of the world. When
exposed to weather, it gradually acquires an earthy appearance, and at
length passes into porcelain clay (118).

Felspar is of great use in the manufacture of the finer kinds of
earthenware. Of the two substances which chiefly compose the porcelain
of China, one called _petunzé_ is a whitish laminar kind of felspar.
This mineral is used in the celebrated porcelain that is manufactured at
Sevres, near Paris, for the purpose of giving to it a white and
transparent appearance. Previously to being used, it is pulverized, made
into a paste, and suffered to dry. It is sometimes applied to the
surface of ornamental vases in the form of enamel.

111. AMAZON STONE _is a green variety of felspar_, which is found in
small rolled pieces on the bank of the river of Amazons, in South
America, whence it has its name. It is susceptible of a beautiful
polish, and is often cut into ring─stones, brooches, and the tops of
snuff─boxes. Lapidaries consider it to be most estimable when
accompanied by mica, which gives it a kind of speckled perlaceous
appearance.

112. _LABRADOR FELSPAR is a very beautiful stone, of smoky grey colour,
intermingled with veins and shades of blue, green, and golden yellow,
exhibiting a brilliant play of_ _colours, according to the position with
respect to the light in which it is held._

The original discovery of this singular mineral was by the Moravian
missionaries, on the island of St. Paul, near the coast of Labrador; but
it has since been found in various parts of Norway and Siberia. Persons
who have passed in boats along the rivers of Labrador, have described
the extremely brilliant and beautiful appearance which the rocks of this
substance frequently exhibit in shallow places, at the bottom of the
water. The visitors of the late Leverian Museum will, no doubt,
recollect a remarkably fine mass of Labrador felspar, the surface of
which was polished, and exhibited some of the most splendid and
beautiful colours that can be imagined. It was considered to have been
the most capital specimen that was ever brought to England.

This mineral, on account of its hardness, its brilliancy, and its
capability of receiving a high polish, is in considerable estimation
among lapidaries for different kinds of ornamental work, particularly
for the tops and bottoms of snuff─boxes, for brooches, and necklaces.

113. _MOONSTONE, or ADULARIA, is the purest kind of felspar that is
known; and is considered to have the same relation to common felspar
that rock crystal has to common quartz. Its colour is white, sometimes
with a shade of yellow, red, or green._

The translucent varieties of this stone, when viewed in a certain
direction, sometimes exhibit a pearly and silvery play of colour. These
are valued by jewellers, who cut them into a semi─globular form, and
sell them under the name of moonstone. Those specimens are considered
most estimable which, when cut in a very low oval, present the silvery
spot in the centre of the stone. They are generally used for rings and
brooches; and when set round with diamonds, their pearly lustre exhibits
a striking and agreeable contrast with the brilliancy of that gem.

Adularia is said to have been first discovered by an Italian
mineralogist, near Mount St. Gothard, in Switzerland. He named it
Adularia felspar, in the belief that the mountain on which he had found
it was named Adula. This, however, was not the case; for Mount Adula is
at some distance from St. Gothard, in the Grisons. This mineral has
since been found in the granite of the island of Arran, in France, and
Germany. The finest specimens are brought from Ceylon.

                                ───────




                         ORDER II.–SOFT STONES.

                 (Those which will not scratch Glass.)

                                ───────

                              CLAY FAMILY.

114. Clay is a mixture of alumine (33) and silex (38), and is too well
known to require much description.

It is opaque, has an earthy texture, is about twice as heavy as water,
when moistened is very ductile, adheres slightly to the tongue; and with
its peculiar smell (called clayey) every one is acquainted.

115. _COMMON CLAY, or POTTER’s CLAY, which is found in nearly every
country of the world, is sometimes white, has a blue or yellowish tinge,
or is brown or reddish._

It is the peculiar quality of this substance to become so hard by heat
that it will even strike fire with steel. The ductility of clay, and its
property of thus hardening in the fire, have rendered it an article of
indispensable utility to mankind in all civilized countries. It is
formed into eating vessels of almost every description; plates, dishes,
cups, basins, bowls, and pans for keeping provisions in. For these
almost any kind of clay may be advantageously used; but it is necessary
to mix it with sand, for the purpose of rendering the vessels that are
made of it more firm and strong. Those that are applied to culinary, and
other uses in which it is requisite for them not to be penetrable by
water, are covered with a glazing. This glazing, for coarse ware, is
sometimes made with lead, and sometimes by throwing a certain portion of
salt into the furnace. In the formation of the better kinds of
earthenware, the clay is made into a paste with water, moulded into the
requisite shape upon an horizontal wheel, the inside being formed by one
hand of the potter, and the outside by the other, as the wheel turns
round. When the pieces have been baked, they are dipped into a glazing
mixture, consisting of white lead, ground flints, and water, and are
exposed a second time to the fire. The different colours of earthenware
are obtained by means of various kinds of metallic oxides (21).

The coarser kinds of clay are manufactured into _bricks_ for the
building of houses, and _tiles_ for the covering and paving of them.
These are formed in moulds of the requisite shape, afterwards dried for
some time in the sun, and finally piled in kilns, and there baked to a
proper degree of hardness. The earth for bricks ought to be sufficiently
fine, free from pebbles, and not too sandy, which would render them
heavy and brittle; nor ought it to be entirely free from sand, as this
would make them crack in drying.

Clay is a substance of inestimable value for forming the bottoms of
ponds, and the bottoms and sides of canals and reservoirs, to prevent
the water from draining away. It also composes, in a great measure,
those tenacious earths called arable soils. What is peculiarly
denominated clay land is known by its holding water, and not soon drying
when wetted. Such land requires much labour from the husbandman, before
it can be sufficiently pulverized, or brought to a fit state for being
productive of corn or grass.

116. PIPE CLAY _is a fine and yellowish white variety of common clay_.
It is very plastic, adheres strongly to the tongue; and, in a strong
heat, is hardened, and rendered perfectly white.

It is of this clay that tobacco pipes are made, by the simple process of
casting them in moulds, forming a hole through the stems by means of a
wire, generally dipping the small end into some glazing material, and
then baking them. Pipe clay is also formed into oblong pieces, dried,
and employed for cleaning white woollen cloths, and for various purposes
of domestic utility. It is likewise the basis of the yellow, of what is
called _Queen’s ware_ pottery. This is glazed in a manner somewhat
different from that of common pottery. The glazing mixture consists of a
certain proportion of carbonat of lead (239), ground flint, and flint
glass, worked with water to the thickness of cream. The ware, before it
is glazed, is baked, and thus acquires the property of strongly imbibing
moisture. It is then dipped into the above composition; exposed a second
time to the fire, by which the glaze it has imbibed is melted. A thin
glossy coat is thus formed upon its surface, which is more or less
yellow, according to the greater or less proportion of lead that has
been used.

117. _LOAM is a yellowish or brownish kind of clay; sometimes containing
a considerable proportion of sand. It occurs in immense beds, and is
found in almost every part of the world._

This substance, when mixed with straw or hair, to prevent it from
cracking, is extensively used for the building of what are called mud
cottages or houses. These are generally reared on a foundation of stone,
or brickwork, to secure them from injury by the moisture of the earth.
It is said to be the most advantageous practice to form the loam into
bricks, and to dry these in the shade, and afterwards in the sun. The
use of such bricks is of great antiquity. We are informed that the
ancient city of Damascus, and even the walls of Babylon, were
constructed of bricks made of loam.

118. _PORCELAIN CLAY is generally of white or reddish white colour,
sometimes inclining to yellowish or grey. When dry, it absorbs moisture
rapidly; and it becomes very tenacious when kneaded._

_It is known from the other clays by the fineness of its particles, its
soiling the fingers much when handled, and its fine but meagre feel._

The usual distinction betwixt earthen ware and porcelain is, that the
former is opaque, and the latter semi─transparent. In the manufacture of
porcelain the clay is sometimes used alone, and sometimes intermixed
with other earths, or with felspar (110). The earliest manufacture of
porcelain is supposed to have been that in China and Japan. The quantity
produced in China must formerly have been extremely great; as not only a
considerable portion of the eastern parts of the world, but almost the
whole of Europe, was supplied with it. In a single province it is said
that nearly a million of persons were at one time employed in this
manufacture.

The manufactory at Sevres, in France, has long been celebrated both for
the excellence and elegance of its porcelain. There are well─known
manufactories of porcelain at Meissen in Saxony, at Berlin, and in
Austria; but none of these are at present superior to our own, in
Worcestershire and Staffordshire.

Porcelain clay occurs chiefly in countries which abound with granite
(251) and gneiss (255). It is found in small quantity in Cornwall, and
other granite districts of England, as well as in those of Scotland and
Ireland. But the most valuable kinds of this clay are found in China and
Japan.

The mineral is not used in the state in which it is found in the earth;
but is previously washed several times to free it from impurities. After
the process of washing, only about fifteen parts of pure clay remain:
this is the _kaolin_ of the Chinese. To form the composition of the
porcelain, this clay is mixed, in certain proportions, with quartz (76),
flint, gypsum (192), steatite (124), or other substances; and the
mixture is sifted several times through hair sieves. It is afterwards
moistened with rain water, and, in the form of a paste, is put into
covered casks. Here a fermentation soon takes place, which changes its
smell, colour, and consistence. Its colour passes from white into dark
grey; and the matter becomes both tougher and more soft than before. The
peculiar mode of preparing this mixture, and the art of rightly managing
it, are secrets in most porcelain manufactories.

The next operation consists in giving to the paste thus formed the
requisite shape of the vessels. This is done first by kneading it with
the hands; and then by taking up certain portions of it, and turning it
on a lathe, in the manner of common pottery (115), but with more care.

The third operation is the baking or firing. This is done in furnaces of
a particular construction, and generally lasts from thirty─six to
forty─eight hours. The state of the baking is shown by proof pieces, as
they are called, which are placed in convenient situations, and can be
drawn out, from time to time, for examination. The porcelain in this
state, is named _biscuit porcelain_; and figures, and such other
porcelain articles as are neither to be painted nor exposed to water are
in the state of biscuit.

A fourth operation is covering the surface of the biscuit with a varnish
or enamel. This is composed of pure white quartz (76), white porcelain,
and calcined crystals of gypsum (192); and sometimes principally of
felspar (110). These substances are carefully ground, then diffused
through water, and formed into a paste. When used, the paste is diluted
in water, so as to give it considerable fluidity; and the pieces of
biscuit porcelain are separately plunged into it, in such manner as to
cover their whole surface. These are then exposed to a heat sufficient
to melt the enamel or covering: and in this state they constitute white
porcelain.

If the porcelain is to be painted, it must again be exposed to heat in
the furnace. The colours used for the painting of it are all derived
from metals; and many of them, though dull when applied, acquire
considerable lustre by the action of the fire. The colours are always
mixed with some kind of flux, such as a mixture of glass (204), borax
(208), and nitre, melted together, and afterwards ground.

Gum or oil of lavender is used for mixing up the colours. When the
painting is finished, the pieces are exposed to a heat sufficient to
melt the flux, and thus fix the colour.

119. _TRIPOLI is a kind of clay of yellowish grey, brown, or white
colour, sometimes striped or spotted, and of an earthy texture._

_It feels harsh and dry to the touch; is soft, scarcely adheres to the
tongue, and will not take a polish from the nail._

This substance obtained its name from having formerly been imported into
Europe from Tripoli, on the north coast of Africa. It is, however, now
found in several parts of Germany; and a granulated kind has been
discovered in England.

Tripoli is used for the polishing of metals and stones. For this
purpose, it is mixed with sulphur, in the proportion of two parts of
tripoli to one of sulphur. These are well rubbed together on a marble
slab, and are applied to the stone or metal with a piece of leather.

When tripoli is combined with red ironstone, it is used for the
polishing of optical glasses. It is sometimes made into moulds, in which
small metallic or glass figures and, medallions are cast; and a kind of
tripoli is found near Burgos, in Spain, which is used as an ingredient
in the manufacture of porcelain.

In Derbyshire,, and several parts of Staffordshire, is dug a kind of
tripoli which has the name of _rotten stone_. This is considered to be a
produce of limestone shale, which has undergone a decomposition by
exposure to the air and moisture. It is used for most of the same
purposes as tripoli.


                           CLAY SLATE FAMILY.

120. _CLAY SLATE, or ROOFING SLATE, is a kind of stone of foliated
texture, and greyish, black, brown, green, or bluish colour._

_It breaks into splinters, does not adhere to the tongue, yields
generally a clear sound when struck, and is nearly thrice as heavy as
water._

Vast and extensive beds of slate occur in different parts of the world;
and this mineral sometimes constitutes even a principal portion of
mountains. In our own country there are many important quarries of it,
particularly in Westmoreland, Yorkshire, Wales, and Derbyshire.

The uses of slate are numerous and important; but its principal use is
for the roofing of houses. For this purpose it is split into thin plates
or laminæ. These are fastened to the rafters by pegs driven through
them; and are made to lap over each other at the edges, in such manner
as to exclude the rain and other moisture. The kinds which are preferred
for this purpose are such as have the smoothest surface, and split into
the thinnest plates. It is requisite that slates should be damp when
they are split, otherwise this cannot be done without difficulty. Hence
it is generally customary to split the masses as soon as possible after
they have been separated from the rock.

Slate should not be porous. If it be so, rain and snow water will pass
through it, and destroy the wood─work of the house on which it is
placed. Porous slate is also liable to have moss and lichens grow upon
and cover it. These plants retain moisture long, and keep the surface,
and even the interior of the slate, moist; so that, during the winter
season, by the freezing of the moisture, the slate is apt to split and
fall into pieces. To ascertain whether the slate be of requisite
compactness, it should be completely dried, then weighed, and afterwards
soaked for some time in water. When taken out it is to be wiped with a
cloth, and again weighed. If it have not acquired any considerable
increase of weight, it is a proof of its being sufficiently compact. If,
on the contrary, it have absorbed much of the water, and have become
considerably heavier by the immersion, it is shown to be of a porous
texture. Slates that are brittle are bad. If they emit a tolerably clear
sound, when struck with a hammer, it is considered a proof that they are
not too brittle: if, on the contrary, the sound be dull, they are soft
and shattery. A good slate ought also to resist the action of a
considerable degree of heat.

The slates that are principally used in London are brought from North
Wales, from quarries that are worked near Bangor. There are also
extensive slate quarries near Kendal, in Westmoreland; and the Kendal
slates, which are of a bluish green colour, are more highly esteemed
than those from Wales. They are not of large size, but they possess
great durability, and give a peculiarly neat appearance to the roofs on
which they are placed. The slate quarries near Easdale, in Scotland, are
so extensive as to furnish annually more than 5,000,000 in number, and
to give employment to upwards of 300 men.

_French slates_ were much used in London about seventy years ago; but
they have been found too small, thin, and light, to resist the winds and
storms of this changeable climate.

Dark─coloured, compact, and solid slates are manufactured into _writing
slates_, or _table slates_, as they are sometimes called. In the
preparation of these, the slate, after it is split of proper thickness,
is smoothed with an iron instrument. It is then ground with sandstone,
and slightly polished with tripoli (119), and, lastly, rubbed with
charcoal powder. It is cut into the requisite shape, set in a wooden
frame, and is then ready for use.

For writing on these slates, pencils are used which are also made of
slate. These, which are called _slate pencils_, are made of a particular
kind of slate, that, on splitting, falls into long splintery fragments.
It is necessary that the pencils should be considerably softer than the
slate to be written upon, so that they may leave a whitish streak on its
surface, without scratching it. Such is the shivery nature of the slate
of which they are made, that, if it be exposed for some time to the
action of the sun or frost, it is rendered useless. Hence, workmen are
careful to cover it up and sprinkle it with water, as soon as it is
taken from the quarry, and to preserve it in damp cellars. The pieces
are afterwards split by a particular instrument, and then wrought into
the requisite shape.

In some of the quarries in Derbyshire and Wales the slate is so thick as
to admit of being split into large and tabular pieces. These are used
for gravestones, and for slabs for dairies and cellars. Paving stones
and mile─stones are also formed of them; and vessels for the salting of
meat, and setting of milk in dairies. For the latter use slate is
peculiarly well adapted, on account of its resistance of greasy or oily
substances. But this property renders it unfit for any purpose for which
it is requisite to be painted; as, the oil not entering the stone, the
paint soon peels off, and leaves the stone as black as it was at first.
Cut into narrow strips, slate has also been applied, in the
neighbourhood of Bangor, North Wales, for the formation of fences.

When sufficiently solid for the purpose, slate is cut into inkstands,
and turned into vases, and fancy articles of various kinds. And a
singular circumstance has been remarked, that, if a window or door be
suddenly opened, in an apartment where the workmen are turning these,
they will sometimes fly in pieces; though, after the work is finished,
they may be exposed to the usual changes of temperature without injury.

Pounded slate is advantageously used for cleaning iron and other works
in metal. When well ground, and mixed with a certain proportion of loam,
slate is made into moulds for the casting of metals in; and, when burned
and coarsely ground, is used instead of sand in the making of a solid
and impermeable mortar or cement, for the parts of buildings that are
covered with water.

121. _BLACK CHALK, or DRAWING SLATE, is an earthy substance, of slaty
texture; generally of a greyish, sometimes a bluish black colour._

_It is soft and smooth to the touch, and, in handling, stains the
fingers._

To crayon painters, and other artists, black chalk is a very useful
article. Considerable quantities of it are imported from France, Spain,
and Italy. The best is brought from Italy. This is more free from gritty
particles, more firm and compact in its texture, and in its touch much
smoother than the chalk of any other country. It contains somewhat more
than one─tenth part of its weight of charcoal. When prepared for use, it
is cut into square pieces, which are sometimes enclosed in wooden cases,
like black lead pencils. These pencils are said to become dry, hard, and
unfit for use, by long keeping. To preserve them in greatest perfection,
they should be kept in a moist place. Some artists prefer pencils that
are made of the chalk finely ground, mixed with a certain proportion of
gum water, and cast in moulds. Care should be taken not to put too much
gum, as the pencils will not, in such case, leave any mark on the paper.

Drawing slate is sometimes used as a black colour for painting. For this
purpose it is pounded or ground, and then mixed with oil or size,
according to the kind of work for which it is required. When black chalk
is strongly heated, it loses its colour, and assumes that of a reddish
grey.

122. _HONE, or WHET SLATE, is a well─known kind of stone, of somewhat
slaty texture, and generally of dull white, or greenish grey colour. Its
surface is smooth, and feels unctuous to the touch._

These stones, when properly cut and smoothed, are of indispensable
utility to carpenters, cutlers, and others, for sharpening their cutting
instruments upon. Those of the finest grain are used for lancets,
penknives, and razors. For this purpose their surface, when used, is
covered with a small quantity of oil; by which, after a while, they are
rendered considerably harder than they were at first. They ought to be
kept in damp and cool places; for, if much exposed to the sun, they
become too hard and dry for many purposes to which they are applied.

There is a vulgar and erroneous notion that hones are holly wood, which
by lying in petrifying water, have been thereby converted into stone.
The greater number of them have a fine and a coarse side. From the
circumstance of their having been originally brought into this country
from Turkey and the Levant, they are sometimes called _Turkey stones_.
They are now found in Saxony and Bohemia, in North Wales, and near
Drogheda, in Ireland.

The powder of whet slate is sometimes used, instead of emery, for the
cutting and polishing of metals.


                              MICA FAMILY.

123. _COMMON MICA, GLIMMER, or MUSCOVY GLASS, is a mineral substance of
foliated texture, which is capable of being divided into extremely thin
leaves that have a sensible elasticity, and are transparent._

_The colour of mica is greenish, sometimes nearly black, reddish, brown,
yellow, or silvery white, with, occasionally, a metallic lustre on the
surface. Mica is so soft as easily to be scratched; and, when divided
across the plates, seems rather to tear than break._

This is one of the most abundant mineral substances that is known. It
not only occurs in a massive and crystallized state, but it enters into
the composition of many rocks; is found filling up their fissures, or
crystallized in the cavities of the veins which traverse them. In some
countries, as in Siberia, it is an article of commerce, and is obtained
from mines like other minerals. From these it is extracted by hammers
and chisels. It is then washed, to free it from the impurities which
adhere to it; split into thin leaves or pieces; and assorted into
different kinds, according to their goodness, purity, and size. We are
informed by the Abbé Haüy, that plates of mica a yard or more in width
have been obtained from the mines in some parts of Russia.

Thin plates of mica are adopted, in many parts of Siberia and Muscovy,
to supply the place of glass for windows. In the shipping of Russia it
is considered preferable to glass, as the concussion produced by the
firing of the guns does not shatter it. It is employed instead of window
glass in Peru and New Spain; and also in Pennsylvania. Mica may be
advantageously substituted for horn in lanterns, as it is not only more
transparent, but is not susceptible of injury from the flame of the
candle. It has, however, the inconvenience of soon becoming dirty; and
of having its transparency destroyed by long exposure to the air. Mica
is used for enclosing objects that are intended to be viewed by
microscopes.

So plentiful is this substance in Bengal, that, for the value of five
shillings, as much of it may be purchased as will yield a dozen panes,
each measuring about twelve inches in length and nine in breadth, and so
clear as to allow of ordinary objects being seen through them at the
distance of twenty or thirty yards.

Mica, when powdered, is sold by stationers on the Continent, in place of
sand, for absorbing ink in writing, but it does not dry sufficiently
quick to be of much use in this respect. In Russia it is employed in
different kinds of inlaid work. It is sometimes powdered, and intermixed
with the glaze in particular kinds of earthen ware. The heat which melts
the glaze has no effect on the mica: hence it appears, dispersed
throughout the glaze, like plates or scales of silver or gold. Some
artists use it in making artificial avanturines (85).

It must be observed that the best mica is of a pure pearl colour; and,
when split into leaves, presents a smooth surface.


                           SOAPSTONE FAMILY.

124. _STEATITE, or SOAPSTONE, is a soft and unctuous substance, which
has much the appearance of soap; and is generally of a white or grey
colour, intermixed with greenish or yellowish shades._

_It is somewhat more than twice as heavy as water; and is distinguished
from indurated talc (135) by not splitting, like that substance, into
slaty fragments._

In the counties of Devon and Cornwall, and the islands in the vicinity
of the Lizard Point, this mineral is found in considerable abundance. It
possesses many of the same properties as fullers’ earth, and is, like
that substance, employed in the scouring of woollen cloths. When mixed
with water it may be formed into a paste; and, in this state, it is
easily worked, like clay, for the manufacture of earthen ware. In the
porcelain manufactory at Worcester considerable quantities of steatite
are employed. According to Dr. Shaw, the Arabs use it in their baths,
instead of soap, to soften the skin.

As it becomes hard in the fire, and does not alter its shape, this
substance has been successfully adopted for imitations of engraved gems.
The subjects are engraved upon it with great ease in its natural state;
it is then exposed to a strong heat; afterwards polished, and then
coloured by means of certain metallic solutions.

We are informed by travellers, that some of the savage tribes eat
steatite, either alone, or mixed with their food, to deceive hunger. The
inhabitants of New Caledonia eat considerable quantities of it.
Humboldt, the South American traveller, assures us that the Otomacks, a
savage race of people, who live on the banks of the Orinoco, are almost
wholly supported, during three months of the year, by eating species of
steatite, or potter’s clay, which they first slightly bake, and then
moisten with water. M. Golberry says that the negroes near the mouth of
the Senegal mix their rice with a white kind of steatite, and eat it
without inconvenience.

In some parts of Spain a variety of steatite is found, which is used by
artists under the name of Spanish chalk. When slightly burned, this
mineral is sometimes used as the basis of rouge.

125. FIGURE STONE _is a kind of steatite, which has, internally, a
glimmering and resinous lustre, and a slaty or splintery fracture_.

From its softness, and yet solidity of texture, this mineral can easily
be fashioned into various shapes, even with a knife. Hence in China,
where it frequently occurs, it is cut into grotesque figures of various
kinds, which the French call _magots de la Chine_, into cups, vases,
pagodas, snuff─boxes, and other articles.

126. _MEERSCHAUM, or SEA─FROTH, is a singular kind of mineral, of
yellowish or greyish white colour, sometimes so light as to float in
water: when fresh dug it has nearly the consistence of wax._

_If exposed to a strong heat, it becomes so hard as to yield sparks with
steel._

The principal use to which meerschaum is applied is in the formation of
the bowls or heads of tobacco─pipes used by the Turks, and the quantity
consumed for this purpose is very great. It is found in a fissure of
grey, calcareous earth, about six feet wide, near Konie, in Natolia,
where upwards of six hundred men are employed in the digging and
preparation of it; and the sale of it supports a monastery of dervises
established at that place. The workmen assert that it grows again in the
fissure, and puffs itself up like froth. It is prepared for use by being
first agitated with water in great reservoirs, then allowed to remain at
rest for some time. The mixture soon passes into a kind of fermentation,
and a disagreeable odour, resembling that of rotten eggs, is exhaled. As
soon as this smell ceases, the mass is further diluted with water,
which, after a while, is poured off. Fresh water is repeatedly added,
until the mass is sufficiently washed and purified. The meerschaum, in
this state, is dried to a certain degree. It is then pressed into a
brass mould, and, some days afterwards, is hollowed out so as to form
the head of the pipe. It is subsequently dried in the shade, and lastly
is baked. In this state the pipe heads are brought to Constantinople,
where they are subjected to further processes. They are first bailed in
milk, and next in linseed oil and wax; and, when perfectly cool, are
polished with rushes and leather. The boiling in oil and wax renders
them capable of receiving a higher polish than could otherwise be given.
When thus impregnated, they also acquire, by use, various shades of red
and brown, which are thought to add considerably to their beauty. In
Turkey, and even in Germany, meerschaum pipes that have been much used
are more valued than those newly made, and this solely on account of the
colouring they possess. Indeed there are people in those countries whose
only employment consists in smoking tobacco pipes, until they acquire
the favourite tints of colour. By long use, the heads become black: but
if boiled in milk and soap, they are soon rendered white again.

It is asserted that the Turks spread meerschaum on bread, and eat it as
a medicine; and that they cover with it the heads and eyes of dead
bodies, previously to interment. As it lathers with water like soap, it
is used by the Turkish women for washing their hair; and, as it absorbs
oily matters, it is occasionally used, as fuller’s earth is with us, for
the cleansing and scouring of cloth.

We are informed by Pliny, that a kind of bricks were made by the
ancients, so light that, when dried, they would float in water. He
describes them to have been formed of a spongy kind of earth, and to
have had some resemblance to pumice stone, which he says might perhaps
be applied to the same purposes as these bricks, if it could be obtained
and wrought in sufficient quantity. Bricks of similar description have
lately been made of a mineral substance found near Sienna, in Italy, and
which is supposed to be meerschaum.

A kind of meerschaum has lately been discovered, in veins, in the
serpentine (132) of Cornwall.

127. _BOLE is an earthy mineral, of yellowish or reddish brown colour,
soft, and somewhat unctuous to the touch, and generally found in a
massive state._

_It exhibits internally a glimmering lustre; and, when put into water,
immediately absorbs it, and breaks down into small pieces with a
crackling noise. This mineral is farther distinguished by its fracture
being conchoidal, or appearing somewhat like the impression of a shell;
and by its adhering strongly to the tongue._

Although bole is at present little used except as a basis of tooth
powder, and a coarse kind of paint, it was formerly considered an
important article in medicine, and used as an astringent. We are
informed that tobacco pipes are sometimes made of this mineral; and that
it is employed as an ingredient in the glaze of some kinds of earthen
ware.

It is chiefly imported from the Levant; though it has also been found in
considerable beds in Silesia and Saxony.

128. _LEMNIAN EARTH is a kind of bole of yellowish grey, or yellowish
white colour, sometimes marbled with rust─like spots._

_It is distinguished from bole by being dry and not unctuous to the
touch, dull internally, adhering slightly to the tongue, and its
fracture being earthy._

With the ancients this mineral was considered an almost invaluable
medicine. They procured it chiefly from Armenia, and the island of
Lemnos, in the Grecian Archipelago. The Lemnian bole was held so sacred
that it was dug in the presence of the priests of Venus, and, after
having been mixed by them with goat’s blood, was moulded into cakes,
which were impressed with the figure of a goat, to authenticate them.
This done, it was administered as a consecrated remedy; and, even so
lately as the sixteenth century, the vein of bole in Lemnos was annually
opened on the sixth of August, and, after certain prayers by the
priests, so much of the earth was taken out as was thought sufficient
for the consumption of the ensuing year. The entrance was then closed,
and the severest punishments were denounced against any one who should
open it without permission. A portion of the earth was sent to
Constantinople, where it was made into small cakes, and sealed by the
ministers of the Emperor; the remainder was prepared in the island, and
was impressed with the seal of the Governor. Not many years ago, it was
customary with certain empirics on the Continent, to sell this substance
in sealed packets, as a nostrum of great value, and particularly as
possessing astringent properties of very extraordinary nature.

129. _FULLER’s EARTH is a well─known mineral, generally of greenish
colour, more or less mixed with brown, grey, or yellow: of soft and
almost friable texture, and somewhat unctuous to the touch._

_When put into water it immediately absorbs it, and breaks down into a
fine pulp._

This earth is valuable for its property of taking grease out of woollen
and other cloths, which, on a large scale, is effected by the operation
called _fulling_, whence its name has been derived. This operation,
which is performed by a kind of water mill, called a _fulling mill_, is
particularly necessary with respect to new cloths, to extract from them
the grease and oil that have been used in their preparation.

Fuller’s earth was formerly considered an article of such importance in
England that its exportation was prohibited under severe penalties. It
was then employed for most of those purposes for which soap has since
been so extensively applied. In the dressing of cloth it is now so
indispensable, that foreigners, although they can procure the wool, are
never able, without fuller’s earth, to reach the perfection of the
English cloths: and, in this country, incalculable quantities of it are
consumed. As an article of domestic utility, it might be much more
frequently used than it is, as a substitute for soap, in the cleaning
and scouring of wooden floors and wainscots.

There are extensive beds of fuller’s earth in several of the counties of
England. London is principally supplied from those of Kent, Sussex, and
Surrey. At Wavedon, near Woburn, in Bedfordshire, a peculiarly fine kind
is dug up from pits at the depth of ten or twelve feet below the surface
of the ground; and no country in the world is known to produce fuller’s
earth of quality so excellent as that obtained in England.


                              TALC FAMILY.

130. _JADE, or NEPHRITE, is a very hard and tough species of stone, of
greenish or olive colour, somewhat unctuous to the touch, and looking as
if it had imbibed oil._

_It is found massive, in blunt─edged or rounded pieces._

Nothing has so much tended to make this stone known, as a superstitious
notion that a piece of it suspended to the neck will dissolve stones in
the kidneys. Hence has been attained its appellation of nephrite, or
divine stone; and hence have originated all those numerous amulets in
the form of oval plates, hearts, fishes, birds, &c. pierced with holes
for ribbons to pass through, which are seen in collections of the
curious. Some of the Indian nations make talismans of jade.

From the roughness and tenacity of this stone, in addition to its
hardness, it is very difficult to be cut and polished; and even the best
polish which it is capable of taking as so imperfect, that a person
ignorant of its nature might consider it to be merely smoothed and
rubbed with oil. The ancient artists executed in it many beautiful and
delicate figures; and it is impossible but to admire the industry and
perseverance by which they produced even chains, and other hollow kinds
of work, in jade.

The Turks cut it into handles for sabres and daggers, and into several
kinds of vessels, to which they attach great value.

Jade occurs in granite (251) and gneiss (255) in Switzerland; but the
most beautiful specimens of this mineral are brought from Persia, Egypt,
and Siberia.

131. AXESTONE _is a kind of jade, but differs from it in having a slaty
texture; and in being less transparent and less tough_. This stone is
found in China, New Zealand, and on the banks of the river of Amazons,
in America. And it is said that several of the tribes of American
Indians form of it the axes which they use in place of iron. To explain
how these people have been enabled to work a substance so rebellious as
this is even to the file, and to other instruments of steel (of which
they know not the use), it has been presumed that, when the stone is
first taken from the earth, it is considerably less hard than when, by
drying, its humidity is evaporated: that in this state they work it, and
subsequently harden it, in some peculiar manner, by exposure to heat.

132. _SERPENTINE is a stone which, when polished, has a near resemblance
to marble, is of dark green colour, or reddish; variously streaked, and
spotted with lighter green, red, brown, and yellow._

_It is found in beds, and in a massive state; is translucent at the
edges; and, when pounded, the powder feels soapy to the touch._

There are few stones likely to prove more valuable in ornamental
architecture, both for beauty and durability, than this. It admits of an
excellent polish, which is not easily injured by the effects of air or
water. It is also too hard to suffer the same inconveniences of being
scratched or broken as marble; and its colours are stated to be
indestructible. And such is the size of many of the blocks of
serpentine, that columns of almost any dimensions may be wrought out of
them.

Of the serpentine obtained from the Island of Anglesea, and lately known
by the name of _Mona marble_, a great proportion was sent to London by
Messrs. Bullock and Co. who, until the death of Mr. Bullock, had a large
warehouse and polishing rooms for it in Oxford─street. The prevailing
colours of this stone are red and green. The quarries were worked by
them to considerable extent. They manufactured it into chimney pieces,
slabs, columns, and other articles; and its great beauty, and its
excellence, in many respects, over the generality of marbles, will
recommend it strongly to the public notice.

The chief places in which serpentine has hitherto been found are near
Bareuth, and Zöblitz, in Saxony; in some districts of Cornwall; about
six miles west of the Paris copper mine, in the island of Anglesea; at
Portsoy, in Bamffshire, and other parts of Scotland; and at Cloghan Lee,
in the county of Donegal, Ireland.

At Zöblitz there are some extensive manufactories, in which serpentine
is made into vessels and ornaments of various shapes, that are carried
for sale over nearly all parts of Germany. Several hundred persons are
there employed in the working of this stone.

The name of serpentine is derived from some of the varieties appearing
coloured and spotted like a serpent’s skin. This stone, when found
intermixed with primitive limestone, or crystalline white marble,
differs in no respect from the celebrated _verde antique_ marble (149).

133. _POTSTONE, or LAPIS OLLARIS, is a greenish grey stone, unctuous to
the touchy and so soft when first taken from the quarry as to yield to
the pressure of the nail, yet not easily broken._

_It is found in a massive state._

In consequence of the softness and tenacity of this stone, it can be
turned upon a lathe, and otherwise cut and wrought with great ease.
Hence, in Egypt, Lombardy, Norway, and other countries where it is
found, it is formed into various kinds of culinary vessels and lamps,
which harden in drying, and are capable of withstanding the strongest
action of fire. Vessels of this description were known to the ancients;
and are particularly mentioned by Pliny, the Roman naturalist, who
speaks of some that were highly wrought being very valuable.

Potstone is used in some countries for the lining of stoves, furnaces,
and ovens; and it is so durable as to have, in some instances, stood
unimpaired for several hundred years.

On the banks of the Lake Como, there were some extensive quarries of
potstone, which had been worked from the beginning of the Christian era.
These quarries, however, fell in, on the 25th of August, 1618, and
destroyed the neighbouring town of Pleurs; which had previously obtained
by means of them an annual revenue of about sixty thousand ducats.

134. _COMMON, or VENETIAN TALC, is an earthy stone, capable of being
divided into plates or leaves, which are soft and unctuous to the touch,
somewhat transparent, and usually of greenish silvery white colour._

_It leaves a white trace when rubbed upon any object._

_Mica and talc have a near resemblance to each other; but the plates of
the former, when bent, are elastic, while those of the latter are not._

Venetian talc is very abundant in the Tyrol and the Valteline. In a
state of powder it renders the skin soft and shining; a property which
appears to have suggested the idea of employing it as the basis of the
cosmetic named _rouge_. This is prepared by rubbing together, in a warm
mortar, certain proportions of carmine, or extract of the flowers of
_carthamus tinctorius_, with finely powdered talc, and a certain portion
of oil of benzoin.

The Romans prepared a beautiful blue or purple colour, by combining
pounded talc with the colouring fluid of some particular kinds of
testaceous animals, that are found among the submarine rocks of the
coasts of the Mediterranean. According to Tavernier, the French
traveller, the Persians whiten the walls of their houses and gardens
with lime, and then powder them with a silvery white kind of talc;
which, he says, gives to them a very beautiful appearance. Talc is now
used by the Chinese, and was formerly used by the Europeans, in
medicine,

135. _INDURATED TALC, or FRENCH CHALK, is a heavy mineral, of close
texture, and generally of greenish grey colour; unctuous to the touch,
and having a somewhat slaty fracture._

_It is found in a massive state; and leaves a white trace when rubbed
upon any object._

This is a well known substance, which is in great request by carpenters,
tailors, hat─makers, and others, as the lines that are drawn with it are
not so easily effaced as those that are made with chalk, and
particularly as they remain unaltered even under water. If lines be
traced with it on glass, they remain invisible, or at least are scarcely
perceptible by the naked eye, till breathed upon. This, it has been
conjectured, in part depends on the comparative softness of the
substance with which the impression is made; the condensation of the
breath taking place more readily on the glass than on the talc that
covers it, and the impression of the talc becoming more apparent by the
contrast.

Indurated talc, when reduced to powder, is frequently employed for the
purpose of removing stains, occasioned by grease, from silk and cloth.
This it does effectually, and, in general, without injuring even the
most delicate colour. Like potstone, it is sometimes manufactured into
culinary vessels.

This mineral is found in several parts of the continent of Europe; and
in Cornwall, Scotland, and the Shetland Islands.

136. _ASBESTOS is a greenish or silvery white mineral, of fibrous
texture, which is found in many mountainous countries of the Continent,
in the island of Anglesea, and in Scotland. It occurs in shapeless
masses, and varies much both in weight and hardness._

The name of asbestos is derived from the Greek language, and signifies
that which is inconsumable. This mineral, and particularly a silky
variety of it, in long slender filaments, called _amianthus_, was well
known to the ancients. They made it into an incombustible kind of cloth,
in which they burned the bodies of their dead, and, by which means, they
were enabled to collect and preserve the ashes without mixture. In the
manufacture of this article they were not able to weave the asbestos
alone; but, in the loom, were obliged to join with it linen or woollen
threads, which were afterwards burned away.

Incombustible cloth was purchased by the Romans at an enormous expense.
Sir J. E. Smith, when at Rome, saw a winding sheet of amianthus in the
Museum of the Vatican. It was coarsely spun, but as soft and pliant as
silk. The person who attended him set fire to one corner of it; and the
same part burned repeatedly with great rapidity and brightness, without
being at all injured. This interesting relic was discovered, in the year
1702, in a funeral urn, and contained burned bones, together with a
quantity of ashes. It was nine Roman palms long, and about seven in
width, and had been deposited in the library of the Vatican by order of
Pope Clement the Eleventh.

Cloth made of amianthus, when greased, or otherwise contaminated with
dirt, may be cleansed by throwing it into a bright fire. In this process
the stains are burned out, and the cloth is restored to a dazzling white
colour. Pliny, the Roman naturalist, informs us that he had himself seen
table─cloths, towels, and napkins of amianthus taken from the table of a
great feast, thrown into the fire, and burned before the company: and by
this operation, he says, they became better cleansed than if they had
been washed.

The inhabitants of some parts of Siberia manufacture gloves, caps, and
purses of amianthus; and in the Pyrenees it is wrought into girdles,
ribbons, and other articles. The finest girdles are made by weaving the
most beautiful and silky filaments with silver wire. These are much
prized by the women, not only on account of their beauty, but from
certain mysterious properties they are supposed to possess.

The shorter fibres of amianthus have sometimes been manufactured into
paper, but this is too hard for use. It has, indeed, been proposed to
preserve valuable documents from fire, by writing them on paper made of
amianthus. Such a plan might deserve consideration, if we possessed
fire─proof ink; but until this be obtained, the fire─proof paper will be
of little use.

When several of the long fibres of this mineral are placed together,
they may be formed into wicks for lamps; and it has been asserted that
such wicks are incombustible. Kircher, the German philosopher, had a
wick made of amianthus which burned for two years without injury, and
was at last destroyed by accident. It is said that the inhabitants of
Greenland make use of amianthus for the wicks of their lamps.

This substance, although it will long continue unaltered in considerable
heat, yet if the heat be much increased it ceases to withstand it, and
is melted into a dense kind of scoria. In the island of Corsica asbestos
is advantageously employed in the manufacture of pottery. Being reduced
into fine filaments, it is kneaded with clay; and vessels made of this
mixture are said to be lighter, less brittle, and more capable of
sustaining sudden alterations of heat and cold than common earthenware.


                           CHRYSOLITE FAMILY.

137. _CHRYSOLITE, or PERIDOT, is a soft gem, usually of yellowish green
colour, though sometimes it is grass─green, or bluish green, but with a
tinge of brown._

_It is generally found in fragments and rounded pieces, and rarely
crystallized. In the latter case its regular form is an eight, ten, or
twelve─sided prism._

Though scarcely harder than glass, and consequently inferior to most
other gems in lustre, these stones are not unfrequently used in
jewellery, particularly for necklaces and ornaments for the hair; and,
when well matched in colour, and properly polished, their effect is very
good. They are, however, too soft for ring stones; for, by wearing, they
soon become dull on the surface. But it is said that their lustre may,
in some degree, be restored by immersing them in olive oil.

To give the greatest brilliancy to this stone, we are informed by Mr.
Mawe, that a copper wheel is used, on which a little sulphuric acid, or
spirit of vitriol (24), is dropped; and that, during the process, an
highly suffocating odour is given out. But he is of opinion that the
most advantageous way of working it would be that in which glass is cut.

Chrysolite is imported from the Levant, and is said to be found in Upper
Egypt, and on the shores of the Red Sea.


                             BASALT FAMILY.

138. _BASALT is a greyish black and coarse grained stone, which is
usually found either in globular distinct pieces or in groups of large
columns, each of which has from three to eight sides, and is divided
horizontally into numerous stones, that very exactly lie upon, or fit
into each other._

The most remarkable assemblages of basaltic columns that are known are
those called the _Giants’ Causeway_, on the coast of Antrim, in Ireland,
and the _Cave of Fingal_, in the island of Staffa, one of the Hebrides,
or Western Islands of Scotland.

The former, which is believed by the common people to have been an
artificial production, the vast labour of giants who formerly inhabited
the country, consists of an irregular group of many thousand jointed
pillars. Most of these are of considerable height; are in general
five─sided, fifteen or sixteen inches in diameter, and each perfectly
distinct from top to bottom, though so closely and compactly arranged
that it is scarcely possible to introduce any thing betwixt them. This
assemblage of columns extends into the sea to a distance unknown, and
along a tract of the sea coast of nearly six miles.

The Cave of Fingal is accessible only by sea, and is formed by ranges of
massive basaltic columns, fifty feet and upwards in height. The stone of
which these columns are formed very much resembles that of the Giants’
Causeway.

In several parts of the world large masses of basalt are discovered,
composing entire insulated mountains, of somewhat conical form. They are
considered by some writers as volcanic productions, but the proofs of
this are by no means satisfactory.

Amongst the uses to which basalt has been applied, two of the most
important are as materials of an excellent and durable kind for building
and paving. When burned and pulverized, these stones impart to mortar
with which they are mixed the property of hardening under water. They
easily melt, without any addition, into an opaque and black glass; and
from them, under a certain modification, bottles of olive─green colour,
and of extreme lightness, but great strength and solidity, have been
formed. Some of the kinds have been advantageously employed as
millstones. Basalt is occasionally used by artists for touch or
teststones, to ascertain the purity of gold and silver; and goldbeaters
and bookbinders, on the Continent, usually make their anvils or beating
blocks of it.

Basalt, though harder, more brittle, and less pleasing in its colours
than marble, was in considerable esteem among the sculptors of
antiquity, on account of its great durability. Many fine works were
consequently executed by them in this stone. Pliny, who has described
several, states that the columns of it were sometimes so large as to
admit of several figures being wrought out of them. The Emperor
Vespasian had an entire statue, accompanied by the figures of sixteen
children, cut out of a single column of basalt; this statue he placed in
the Temple of Peace, and dedicated it to the Nile. The famous statue of
Minerva, at Thebes, is described by travellers to have been formed of
basalt. Antiques of basalt are always in a much better state of
preservation than those of marble. Even such as are dug out of the earth
still retain their original polish; and the finest touches of the chisel
upon them are still unimpaired.


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                                ───────

                       ORDER III.—SALINE STONES.

                                ───────


                      LIME, OR CALCAREOUS FAMILY.

139. Lime, after it has been freed from extraneous matters by burning,
is a mineral of whitish colour, and pungent, acrid, and caustic taste.
It has the property of changing vegetable blue colours to green, and of
corroding and destroying animal substances.

This mineral is found in nearly every country of the globe: but, in a
native state, has not hitherto been discovered except in combination
with some acid.[3] The process of purifying lime, or depriving it of the
acid with which it is combined, is by burning. This is done in a large
kind of furnace, called a _kiln_, where the limestone and fuel are
heaped in alternate layers. After it has gone through this process it is
called _quick─lime_, and has the above─mentioned appearance and
qualities.

Footnote 3:

  With _carbonic acid_ (26) it forms common limestone, marble, chalk,
  and some other substances; with _sulphuric acid_ (24) it constitutes
  alabaster, or gypsum; and with _fluoric acid_ (27) it becomes that
  beautiful production, the Derbyshire spar.—All these, having lime for
  their bases, are denominated CALCAREOUS SUBSTANCES.

The uses of lime are numerous and important. The principal of these is
in the formation of _mortar_, or cement for buildings. For this purpose
it is first _slaked_, by having water poured upon it: a violent heat is
thereby excited, and the lime falls into powder: it is then formed into
paste by working it with water and sand. This, when dry, becomes
extremely solid, hard, and durable. Various examples might be mentioned
of buildings nearly two thousand years old, where the lime is, at this
day, as hard as the stones which it cements together. Lime is also used
for agricultural purposes: when spread upon land it is supposed to
hasten the dissolution and putrefaction of all kinds of animal and
vegetable substances, and to impart to it a power of retaining the
moisture which is necessary for the vigorous growth of corn or grass. It
is employed in the refining of sugar, in the manufacture of soap, in the
melting of iron, and by tanners, in a state of solution, for dissolving
the gelatinous parts of skins, and removing the hair from them. The
manufacturers of glue mix it with that article, for the purpose of
adding to its strength, and preventing its becoming flexible by the
absorption of moisture. This mineral, if well dried, pounded, and
mingled with gunpowder, in the proportion of one pound to two, is of
great utility in the rending of stones and rocks: the mixture, it is
said, will cause an explosion equal in force to three pounds’ weight of
gunpowder. Lime, if swallowed or inhaled, is a virulent poison. Hence
persons employed in lime─works are subject to very distressing
complaints; and hence, if bread be adulterated with lime, it is
extremely injurious. Notwithstanding this pernicious quality, lime is of
considerable use in medicine. It is chiefly given in a state of
solution, and in the proportion of half a pound of quick─lime to twelve
pints of boiling distilled water. This preparation is called _lime
water_.

The superb basin of Lampi, one of the principal reservoirs which
furnishes the canal of Languedoc with water, was, some years ago, found
to leak at the junction of the stones. The engineer who had the
direction of the works caused lime to be slacked in the water. This,
passing through the apertures betwixt the stones, formed a crust, or
very white covering, over its whole surface, of so hard and durable a
nature, that it now constitutes one solid and undivided substance, which
the water cannot penetrate.

CARBONAT OF LIME.

140. _COMMON LIME is a variety of carbonat of lime, or of lime in
combination with carbonic acid (26), which is harder and heavier than
chalk, usually of a greyish colour, and is always found in a massive
state._

Vast mountains of limestone occur in several countries of the globe; but
no where is lime more abundant than in some parts of England and Wales.
It forms, in particular, nearly the whole mountainous districts of
Derbyshire and Shropshire, and encloses, in its substance, numerous
veins of lead ore, calamine, and other important mineral productions.

Its uses have been already described (139).

141. _CHALK is a white or yellowish kind of limestone, too well known to
need any description._

It is found abundantly in many of the southern counties of England, and
is usually procured from large open places, called chalk─pits, by
digging. In some parts of Kent, however, the workmen save themselves, in
this respect, much trouble. They undermine the sides of hills to a
certain depth, then dig a trench at the top as far distant from the edge
as the mining extends at the bottom. This trench they fill with water,
which soaks through during the night, and the whole mass is thereby
loosened, and falls down before morning.

The harder and more compact kinds of chalk are cut into blocks, and used
as building stones. When burned and formed into lime, chalk becomes an
excellent mortar: nearly all the houses in London are cemented with
chalk mortar. It is also used as lime in agriculture. As it readily
imbibes water, it is used by starch─makers, chemists, and others, to dry
precipitates upon. With isinglass or the white of eggs it forms a
valuable lute or cement. By artists it is in request for the
construction of moulds to cast metals in; and by carpenters and others,
as a material to mark with. Chalk is one of the most useful absorbents
that are employed in medicine: it likewise gives name to an officinal
mixture, to a powder, and a potion.

When pounded and cleared from gritty particles, it has the name of
_whiting_. In this state it is used for the cleaning and polishing of
metallic and glass utensils; for whitening the ceilings of rooms, and
numerous other purposes. _Spanish white_ is the same substance cleansed
with peculiar care; and the _Vienna white_, which is used by artists, is
perfectly purified chalk.

142. _MARBLE is a compact and close─grained kind of limestone; so hard
as to admit of being polished. It is this quality which principally
distinguishes it from other calcareous substances._

Although nearly all the numerous kinds of marble may be burned, and thus
converted into quick─lime, their use in ornamental architecture, &c. is
so important as, in general, to prevent their application to the
inferior purpose of mortar. Marble has been known from a very early
period. The Book of Esther, in the Old Testament, describes the palace
of Ahasuerus to have had “pillars of marble,” and the pavement of “red,
and blue, and white, and black marble.”

It would be impossible, in an elementary work like the present, to
describe, or even to enumerate, all the different kinds of marble which
were known to the ancients, or are known to the moderns. But it is,
perhaps, requisite that an account should be given of some of the most
important of them.

_GREEK MARBLES._—143. PENTELIC MARBLE _is of beautiful white colour, and
nearly resembles the Parian marble_ (145) of the Italians; but it is in
coarser granulations. Sometimes it is splintery. It was obtained from
quarries on Mount Pentelicus, near Athens, and was generally preferred,
by the Grecian artists, to Parian marble. The Pantheon was built
entirely of Pentelic marble; and many of the Athenian statues, and works
carried on near Athens during the administration of Pericles, were
executed in it. Dr. Clarke, however, has observed that while the works
wrought of Parian marble remain perfect to the present time, those of
Pentelic marble have been decomposed by the atmosphere, and sometimes
exhibit a surface as rude and earthy as common lime─stone. There are
numerous examples of Pentelic marble in those works of Phidias which
form the Elgin collection in the British Museum.

144. GREEK WHITE MARBLE.—_The Marmo Greco, of Italian artists, is of
snow─white colour, in fine granulations_; and somewhat harder, and
consequently capable of higher polish, than most other white marbles. It
is found near the river Coralus, in Phrygia.

_ITALIAN MARBLES._—145. PARIAN MARBLE _is of snow─white colour,
inclining to yellowish white_. It is obtained from quarries in the
island of Paros, is finely granular, and, when polished, has somewhat of
a waxy appearance. Parian marble hardens by exposure to the air, and is
one of the most permanent kinds that is known. Varro and Pliny each
state that it was named _lychnites_, by the ancients, from a Greek word
signifying a lamp, because it was generally hewn in quarries by the
light of lamps. The finest Grecian sculpture that has been preserved to
the present time is of Parian marble. The principal statues of it now
extant are the Medicean Venus, the Diana Venatrix, and Venus leaving the
Bath. It is also Parian marble on which the celebrated tables at Oxford
are inscribed.

146. CARRARA MARBLE, the purest of all the kinds with which we are
acquainted, is to this day obtained from quarries near the town of
Carrara. _It is of brilliant white colour, has a granular texture; and,
when broken, sparkles like sugar._ This marble, which is almost the only
one in use by modern sculptors, was also quarried and wrought by the
ancients.

It is susceptible of a high polish, and is applicable to every species
of sculpture, except when, as is too often the case, dark veins intrude,
and spoil the beauty of the work. In the centre of the blocks a
beautiful kind of rock crystals, called _Carrara diamonds_, are
sometimes found.

During the late war with France, the exportation of statuary marble from
the countries under the dominion of Buonaparte was prohibited; and, at
one time, it became so scarce in England as to be sold at the rate of
more than seven guineas per cubic foot. The block of marble for the
statue of his late Majesty in the great Council Chamber at Guildhall,
London, was stated by the public prints to have cost twelve hundred
guineas.

147. LUNI MARBLE _is a snow─white, compact, and finely granular
variety_, which was obtained by the ancients from quarries on the coast
of Tuscany. It was preferred by the Grecian sculptors, both to the
Parian and Pentelic marbles; and it is usually supposed that the
Belvidere Apollo, as well as the Antinous of the Capitol, was wrought
out of this marble. There is now found at Luni a white marble,
variegated with red spots and dots.

148. GREEN ANTIQUE MARBLE, or VERDE ANTIQUE _of the Italians, is a
mixture of white marble and green serpentine_ (132). This is believed to
have been obtained from some part of Italy, but the quarries are not now
known.

149. SIENNA MARBLE _is of close texture, and yellowish colour, disposed
in large irregular spots, surrounded with veins of bluish red, passing
sometimes into purple_. It is not uncommon in the vicinity of Sienna,
and is in great request, throughout Europe, for chimney─pieces and
ornamental furniture.

150. BROCATELLO MARBLE is somewhat like the last; but is also
irregularly marked with various shades of red, and, in some parts, with
white.

151. MANDELATO MARBLE _is of light red colour, with yellowish white
spots_. It is found at Lugezzana, in the Veronese. Another variety,
bearing the same name, occurs at Preosa.

152. VERDE DI PRATO MARBLE _is a green marble, marked with darker green
spots_, which is found near the town of Prato in Tuscany.

153. LAGO MAGGIORE MARBLE _is a beautiful kind, white, with black spots
and dots_. It has been employed for decorating the interior of many
churches in the Milanese.

154. BRETONICO MARBLE.—This beautiful marble, which is found near the
village of Bretonico, in the Veronese, _is varied with yellow, grey, and
rose colour_.

_FRENCH MARBLES._—155. Many valuable kinds of marble are obtained from
different parts of the French territory.

156. CAMPAN MARBLE.—Three kinds of marble are known by this name, all of
them procured from immense quarries at Campan, near Bagnere, in the
Pyrenees. The first, called _Green Campan_, is of pale sea─green colour,
and exhibits, on its surface, lines of much deeper green, forming a kind
of net─work. The second, called _Isabel Campan_, is of delicate rose
colour, with undulating green veins. The third variety, the _Red
Campan_, is of deep red colour, with veins of still deeper red. The
green variegations in this stone are formed by a talcy mineral,
intermixed with the lime─stone.—The Campan marble is well adapted for
slabs, tables, chimney─pieces, and other ornamental purposes in the
interior of buildings; but, if exposed to the weather, the talcose
substances perish, and leave hollow spaces which render its surface
rough and uneven.

157. GRIOTTE MARBLE _is of a deep brown colour, with blood─red oval
spots, formed by shells_. Its name has been obtained from its brownish
colour, being similar to that of the cherries that are called by the
French _griotte_. This marble has, of late, been much used in the
decoration of public monuments, and in splendid furniture, in France.
Some of the ornaments of the Triumphal Arch of the Carousel are made of
it. The department of Herault is the part of France from which it is
obtained. It sometimes contains large white veins, which destroy the
harmony of the other tints.

158. MARQUESE MARBLE.—This, which is obtained from quarries, near the
village of Marquese, between Calais and Boulogne, is marked with
_different shades and variegations of white and brown_. Of this marble
Buonaparte commenced a magnificent column on the heights near the sea,
at Boulogne, to commemorate his victories; but, since his dethronement,
the erection of this structure has been discontinued.

159. SARENCOLIN MARBLE _is distinguished by exhibiting large zones, and
angular spots of yellow or blood─red colour_. It is found at Sarencolin,
in the High Pyrenees.

160. ST. BEAUME, or LANGUEDOC MARBLE, _is of light red colour, marked
with white and grey zones, formed by madrepores_. The eight columns
which adorn the Triumphal Arch, in the Carousel at Paris, are of this
marble. It is obtained from quarries at St. Beaume, in the department of
Aude.

161. BRECCIA MARBLE OF THE PYRENEES.—One kind of this marble contains
black, grey, and red, middle─sized spots in a brownish red ground. It
admits of a good polish. Another kind has an orange─yellow─coloured
ground, containing small fragments of snow─white colour. Both these are
found in the Pyrenees.

_SPANISH MARBLES._—162. Few countries are more productive of marble than
Spain; and in few countries are the public monuments and buildings more
profusely decorated with marble. The vault of the theatre of Toledo is
supported by 350 marble columns; and an ancient mosque at Cordova is
ornamented with 1200 columns, most of which are of Spanish marble. The
palace and church of the Escurial, and many of the churches in Madrid,
are decorated with marbles of the most beautiful description.

163. WHITE SPANISH MARBLE.—Near Cordova; at Filabres, three leagues from
Almeria, in Grenada; and in some other parts of Spain, white marble is
obtained, which is susceptible of a good polish, and is well adapted to
the general purposes of sculpture.

164. SEVILLE MARBLE _is a beautiful red variety, with shining red and
white spots and veins_. In the vicinity of TORTOSA is found a kind of
marble which has a _violet ground, spotted with bright yellow_; and near
GRENADA a marble of _green colour_, which somewhat resembles the
celebrated verde antique (149).

165. SPANISH BRECCIA.—There are several beautiful varieties of breccia
in Spain. At Riela, in Arragon, there is one, composed of angular
portions or fragments of black marble, embedded in a reddish yellow
base. The breccia marble of Old Castile is of bright red colour, dotted
with yellow and black, and encloses fragments of pale yellow, brick─red,
deep brown, and blackish grey colour.

_GERMAN MARBLES._—166. Germany abounds in marbles, and affords many
kinds which are remarkable both for beauty and singularity. Of these the
kind best known is

167. LUMACHELLI MARBLE.—_This exhibits beautiful iridescent colours,
which are sometimes prismatic internally, but more commonly of various
shades of red or orange_; whence it has also obtained the name of _fire
marble_. Few kinds of marble are more generally admired than this. It
has a dark ground, and is marked throughout with the appearance of small
whitish shells, which, in certain parts, refract the most beautiful and
brilliant colours. This marble is cut into the tops and bottoms of
snuff─boxes, and several other ornamental articles. It is found in veins
at Bleyberg, in Carinthia.

168. Many beautiful kinds of marble are obtained from the island of
SICILY, particularly one called _Sicilian jasper_, which is red, with
stripes like ribbons, white, red, and sometimes green. SWITZERLAND
abounds in marbles; PORTUGAL, SWEDEN, and NORWAY afford few. In the
RUSSIAN EMPIRE many have been noticed, particularly among the Uralian
mountains. The late Empress Catharine caused an immense palace to be
built for her favourite Orloff, which is entirely coated, both inside
and outside, with marble. She built the church of Isaac with marbles of
different kinds, on a vast space, near the statue of Peter the Great, in
Petersburgh. We are at present very imperfectly acquainted with the
marbles of ASIA. Dr. Shaw mentions a red marble obtained from Mount
Sinai; and Mr. Morier, in his journey through Persia, speaks of a
beautiful translucent kind which he calls _marble of Tabriz_, and the
colours of which are light green, with veins sometimes of red, sometimes
of blue. He says it is cut into large slabs, some of which he describes
to have measured nine feet in length, and five feet in breadth.—No
account has hitherto been published of the marbles of AFRICA.—In the
United States of AMERICA many kinds of marble have been discovered, some
of which have been wrought, and polished; but very imperfect
descriptions have yet been given of them.

169. Few countries produce a greater variety of excellent marbles than
the BRITISH ISLANDS. Although these marbles are seldom noticed much
beyond the limits of the districts in which they occur, many of them are
admirably adapted for ornamental purposes; particularly for slabs and
chimney─pieces. It is much to be regretted that we should send to
foreign countries for stones which, in many instances at least, could
certainly be as well supplied from our own. The following is an
enumeration of a few of the most important kinds.

_ENGLISH MARBLES._—170. PETWORTH MARBLE, when cut into slabs, is equal,
both in beauty and quality, to many of the marbles imported from the
Continent. The Earl of Egremont has, at Petworth, several chimney─pieces
formed of it. Much of this marble was used in the cathedral church of
Canterbury. The pillars, monuments, vaults, pavement, and other parts of
that venerable structure, have been formed of it. The archbishop’s chair
is an entire piece of Petworth marble. This marble is found in greatest
perfection upon an estate of the Earl of Egremont, at Kirdford. It lies
at the distance of from ten to twenty feet under the surface of the
ground, and in flakes or strata nine or ten inches in thickness.
Petworth marble is also an excellent stone for walls; and, for paving,
it cannot be excelled. When burned, it also constitutes a valuable
manure, superior, as some farmers imagine, even to chalk.

171. PURBECK MARBLE is obtained from the island of Purbeck, in
Dorsetshire. _It is of dark colour, and contains numerous small round
shells_, which, when it is cut and polished, mark it with roundish
variegations of brown, dark green, and grey. This marble was formerly
more used than it is at present. Several of the small columns, and many
of the monuments, in the churches of Dorsetshire, and the adjacent
counties, are formed of it. But it is not so durable as many other
kinds. Wherever it is long exposed to the weather, the surface cracks,
splits off, and becomes defaced.

172. BABBICOMBE MARBLE is one of the most beautiful kinds that is found
in any country. _It varies in colour, from light brown to deep red_; and
large slabs of it have been obtained that are elegantly and diversely
marked, some in streaks, others in spots, and others in different
coloured shades.

This kind is quarried at Babbicombe, in Torbay, Devonshire, and is
extensively manufactured into chimney─pieces in the West of England. An
attempt was lately made to introduce it in London; but, from its not
being the production of a foreign country, this has failed of success.

173. DERBYSHIRE MARBLE.—There are, in Derbyshire, several kinds of
marble, most of which contain an abundance of fossil shells, and other
remains of marine animals. At Wetton, near Ashbourne, a beautiful kind
is obtained, of greyish black colour, which contains a vast number of
whitish and very minute shells. This has the name of _bird’s eye
marble_. Near Monyash a beautiful variety is found, of a cheerful
colour, inclining to brown red, and full of large marine figures in all
directions; these, when the marble is cut, appear white, and afford a
pleasing contrast.

174. KENDAL MARBLE.—Some varieties of black, grey, and brown marble, are
wrought near Kendal, in Westmoreland. These somewhat resemble the
Derbyshire marbles; and, like them, are manufactured into
chimney─pieces, and ornamental slabs for houses. Several of the slabs
are found to contain corallines, and the remains of other marine
animals, which vary their appearance in a very pleasing manner.

The MONA MARBLE is a species of serpentine intermixed with white
limestone: it has been already described (132).

_SCOTTISH MARBLES._—Scotland affords many valuable and beautiful
varieties of marble.

175. TIRIE MARBLE.—Few of the British kinds of marble have been more
admired than that obtained from Tirie, one of the Western Islands of
Scotland. _It is of a reddish, sometimes a delicate rose─coloured tint,
and sometimes white; and is always intermixed with other minerals which
add to its beauty._ The most common of these is of black colour, and
called hornblende; the others are pale green sahlite, blackish brown
mica (123), and green chlorite. In some varieties the hornblende is more
abundant than the marble.

176. ASSYNT MARBLE.—At Assynt, in Sutherland, _a white marble_ has been
discovered, which is perfectly solid and pure, and entirely free from
blemishes or stains. Blocks or slabs of it may be cut of almost any size
that can be required. This marble acquires a smooth surface, but remains
of a dead hue; whence, of course, its uses as an ornamental marble are
much circumscribed.

177. ISLE OF SKY MARBLE.—There is found in the Isle of Sky a marble of
pure white colour, which appears capable of yielding large and valuable
blocks. Its fracture is granular and splintery, and its texture fine. It
is harder, heavier, and more compact than the marble of Carrara (146);
and is apparently well fitted for all the purposes of sculpture. But it
has the defect of being very unequally hard. While some parts of the
stone are nearly as easy to work as that of Carrara, other parts are so
hard as to add a charge of near fifty per cent. to the cost of the
working.

178. SUTHERLAND MARBLE.—Some beautiful specimens of marble of dark brown
colour, veined with whitish, light red, or light brown, have lately been
brought from the county of Sutherland. These appear of close texture,
are susceptible of a beautiful polish, and are capable of being wrought
into extremely beautiful slabs for chimney─pieces and other ornamental
purposes.

179. GLEN TILT MARBLE _is of white or grey colour, and veined or spotted
with yellow or green; some specimens are nearly white_. The granulations
are peculiarly large; and, in its aspect and composition, the Glen Tilt
has great general resemblance to the Pentelic marble (143). This marble
has of late attracted the notice of the Duke of Athol, through the
suggestion of Dr. Macculloch; and chimney─pieces of it have since been
made. It is obtained from a valley of the same name in the county of
Perth.

180. BLAIRGOWRIE MARBLE.—A few miles from Blairgowrie, in Perthshire,
there is an excellent granulated broad─bedded marble, _of sugar─loaf
texture, and as white as the finest statuary marble_. It may be easily
raised in blocks and in slabs of great size, perfectly free from
blemishes. This marble is supposed to be well adapted for ornamental
architecture, but its large sparry texture renders it unfit for the
sculptor.

181. GLENAVON MARBLE _is of white colour, with large granular
concretions_, somewhat like spangles, and as large as the scales of
fishes. This is a valuable kind; but its situation in the forest of
Glenavon, on the property of the Duke of Gordon, is remote and difficult
of access.

182. BALLICHULISH MARBLE.—On the north side of the ferry of
Ballichulish, in Lochaber, there is a rock of marble, of beautiful
_ash─grey colour_, and of a fine, regular, and uniform grain, which is
capable of being wrought into blocks or slabs of any size, and is
susceptible of a fine polish. This marble is finely sprinkled throughout
with grains and specks of pyrites (236), and with grains and specks of a
beautiful lead ore, which to the eye appears to be rich in silver. If
used for ornamental purposes, it would be a bright and beautiful
metallic marble.

183. BLAIRMACHYLDACH MARBLE.—In the bed of a river, at the farm of
Blairmachyldach, about three miles south of Fort William, is a singular
marble, consisting of _a black ground, flowered with white_. It is of
fine close grain, but not very hard. The flowering in it is light, and
beautiful, like fine needle─work, or rather resembling the frosty
fret─work upon glass windows, in a winter morning.

The cutting and polishing of marble appear to have been performed by the
ancients nearly in the same manner as it is with us. In polishing, the
first substance employed is a sharp, coarse─grained sand. Afterwards a
finer sand is used, then emery (58) in different degrees of fineness.
These are followed by a red powder called tripoli (119): and the last
polish is given with putty.

184. _BLACK MARBLE is a species of limestone, of uniform black colour,
and easily distinguishable, by an excessively disagreeable smell, which
is emitted on rubbing two pieces of it together, or striking it with a
hammer._

Few minerals are susceptible of a more beautiful polish than this. It is
consequently much used for chimney─pieces, small columns, vases, and
other ornamental work. There are two quarries of black marble near
Bakewell, in Derbyshire: and it is manufactured to a considerable extent
by Messrs. Brown and Co. at Derby, who have fixed up in their ware─rooms
a large slab of it as a looking─glass.

By the ancients it was much prized. Marcus Scaurus is said to have
ornamented his palace with columns of black marble, each thirty─eight
feet high; and many of the monuments of ancient Persepolis were executed
in it. M. D’Avejan, Bishop of Alais, used a kind of black marble for
paving the apartments of his palace; but the friction and heat rendered
it so fetid that his successors were compelled to substitute another
species of stone in its place.—The pavements, however, of many churches,
and of the porticos of several galleries, on the Continent, are of black
marble.

185. _CALCAREOUS ALABASTER is a species of limestone of somewhat whitish
or yellowish colour, translucent, and internally splendent or shining._

_It is nearly a pure carbonat of lime; and occurs in masses, hanging,
like immense icicles, from the roofs of lime─stone caverns, and also
coating the sides of such caverns._

The formation of this substance is deserving of notice. The water which
oozes through the crevices of limestone rocks, becomes strongly
impregnated with minute particles of lime. This water, when it has
reached the roof or side of a cavern, is generally suspended, for a
considerable time, before a drop of sufficient size to fall by its own
weight is formed. In the interval which thus elapses, some of the
particles of lime are separated from the water, owing to the escape of
the carbonic acid (26), and adhere to the roof. In this manner
successive particles are separated, and are attached to each other,
until what is called a _stalactite_, having somewhat the appearance of
an icicle, is formed. These stalactites are sometimes solid, having a
lamellar structure; sometimes of a fibrous texture, radiating from the
centre to the circumference, as may be observed when they are broken;
and sometimes hollow. If the water collects and drops too rapidly to
allow time for the formation of a stalactite, it falls upon the floor,
and there forms an irregular lump of alabaster, which has the name of
_stalagmite_. In some caverns, the separation of the calcareous matter
takes place both at the roof and on the floor; and, in course of time,
the substance upon each increasing, they meet, and form pillars,
sometimes of great magnitude.

Caverns of this kind occur in almost every country. Those of Derbyshire
are well known; but the most celebrated stalactitic cave in the world is
that of Antiparos, in the Grecian Archipelago.

The kind of limestone formed in the above manner is what the ancients
generally denominated _alabaster_. It was employed by them for the same
purposes as marble, was cut into tables, columns, vases, and sometimes
even into statues. They also used it in the manufacture of vases or
boxes for containing unguents. It is supposed to have been a vessel
formed of this stone that is mentioned in the Gospel of St. Matthew,
where it is said there came unto our Saviour “a woman having an
alabaster box of precious ointment.” In the National Museum at Paris
there is a colossal figure of an Egyptian deity, which is cut in a kind
of alabaster brought from the mountains between the Nile and the Red
Sea.

186. _TUFA, or INCRUSTING CARBONAT OF LIME, is a calcareous substance
deposited by such water as is impregnated with lime._

_It clothes, with a stony coat, the smaller branches of trees, leaves,
moss, plants, and other substances; and thus preserves them from decay,
by protecting them from the action of the atmosphere._

Most of the substances termed by the common people _petrifactions_
belong to this kind of lime. They are, however, merely covered with, and
by no means converted into stone.

The dropping well at Knaresborough, in Yorkshire, is particularly
celebrated for them. An overhanging rock, several yards in depth, has
been gradually formed of the calcareous matter which the water holds in
solution; and, from this rock, it incessantly drops into the basin
below. The persons who have the care of the place constantly keep these
petrified articles for sale. Even old wigs and hair brooms are subjected
to the powers of the water, to furnish subjects for attraction to the
visitors. There are other springs of this description in Oxfordshire and
Somersetshire, and particularly at Matlock, in Derbyshire. We are
informed that at Dalton, on the south side of Mendip, the workmen not
unfrequently discover large pieces of oak enveloped in blocks of stone
which are four or five tons in weight.

Blocks of tufa are, in some countries, cut and used for building stones;
and this substance, when burned, becomes an excellent lime. Pieces of it
are sometimes hollowed, and used as filtering stones.

In the British Museum there is a human skull completely incrusted with
stone, which was found in the river Tiber.

The warm baths of Hungary are often so thickly coated at the sides and
bottom with tufa, that, during certain intervals, it actually fills up
the tubes and canals through which they are supplied. The _fur in
teakettles_ is a somewhat similar deposit from water in boiling.

187. _PORTLAND STONE, BATH STONE, KETTON STONE, are different kinds of
limestone; and, of a texture so hard and compact as to be used in
building._

_They have their names from the places where they are respectively
found, in Portland Island, near Bath, and at Ketton, in the county of
Rutland._

Of Ketton stone several of the colleges in Cambridge are built. Its
grain has a singular resemblance to the petrified roe of a fish, whence
also it is sometimes called _roestone_. The bridges, St. Paul’s
Cathedral, the Monument, and nearly all the buildings of late date in
London, are constructed of Portland stone.

Some of these kinds of stone, when first dug out of the quarry, are so
soft that they are readily worked into any form which use or ornament
may require. This is owing to the moisture with which they are naturally
impregnated; but when they once become hardened, by exposure to the sun
and air, they are extremely firm and solid. On the contrary, other kinds
of limestone that are used for buildings imbibe and retain the moisture
of the atmosphere, in consequence of which they burst or are crumbled by
frost.

We are informed that Portland stone was first used in London in the
reign of James the First, that monarch, by the advice of his architects,
having employed it in the construction of the banquetting house at
Whitehall. After the great fire in London, it was brought into general
use by Sir Christopher Wren.

188. _MARL is a combination of clay, silex (76), and lime: and is
denominated calcareous, argillaceous, or siliceous, as the lime, clay,
or silex, is most abundant._

The calcareous part of marl is frequently composed of shells, whence it
frequently has the name of _shell marl_; and where these are
predominant, it affords an excellent manure for sandy, dry, gravelly, or
light lands. Marl likewise produces very beneficial effects on mossy and
clayey soils; and these effects, where it has been properly applied,
have been observable for twelve or fourteen years. Some kinds of marl
that contain but a small portion of lime have been successfully used in
the manufacture of earthenware.

This mineral is usually found at the depth of from five to nine feet
beneath the surface of the ground, and deposited between beds of clay
and sand. It is dug out with spades; and, in the digging of it, in
Ireland, the workmen not unfrequently meet with the horns of deer and
other curious fossils.

The usual mode by which persons, generally unacquainted with minerals,
distinguish this from other clayey substances, is, to break a small
piece of dry marl into a glass of vinegar. If it be marl it will
immediately dissolve with considerable effervescence; and the briskness
of the effervescence will be in proportion to the quantity of lime which
it contains.

189. _FLORENCE MARBLE is a kind of indurated or hardened marl, and is
remarkable for presenting, when polished, the appearance of ruined
edifices or rocks._

This kind of marble is never used in architecture. Little slabs of it
are cut for Mosaic work, and to be framed like pictures; and the latter,
when of considerable dimensions, are sometimes purchased at a high
price. If held at a distance from the eye, an inexperienced observer
might mistake a slab of Florence marble for a drawing in bistre. Here,
observes a French writer, we remark a shattered Gothic castle, there the
mouldering fragments of a cathedral; in one part ruined walls, and in
another shattered bastions and towers. But, when we approach the
picture, the illusion vanishes, and those imaginary figures which, at a
distance, appeared to be so correctly drawn, become changed into
irregular spots, lines, and shades, which present nothing distinct to
the view.

190. COTTAM MARBLE, which, when cut and polished, also exhibits the
appearance of a landscape, is a kind of compact marl. It has its name
from being found at Cottam, near Bristol.

191. _LIAS, or CALP is a kind of limestone of bluish black, or greyish
blue colour, and composed chiefly of lime, silex (76), clay, and oxide
of iron (21)._

This stone, when burned, forms a cement which has the property of
setting very strongly under water. It has also, of late years, been
employed in a manner which merits particular notice, for the multiplying
of copies of drawings and penmanship. A drawing is made on prepared
paper with a peculiar kind of ink. A slab of lias, about an inch thick,
is then heated; the drawing is placed upon it, and both are passed
through a rolling press. The paper is afterwards wetted, and washed from
the stone; but the ink, being of a gummy or glutinous quality, becomes
in part absorbed by the stone, and remains. The stone is then ready for
the printer. Previously to taking off each impression, the stone is
wetted with a sponge; fresh ink (which is said somewhat to resemble
printers’ ink, and is put on with a ball similar to that used by
letter─press printers) is then applied. This is prevented, by the water,
from adhering to any part except to the ink that had been absorbed, by
the stone, from the paper on which the drawing was originally made.
Paper is then placed on the stone, both are passed through a rolling
press as before, and a perfect impression of the drawing is made upon
the paper.

This art has been practised in Germany with great success; and with the
difference only of the original drawing being made upon the stone
instead of paper. Many beautiful specimens of drawings, taken from slabs
of lias, may be seen in this country. It is said that copies of military
drawings and orders were, to a very large amount, multiplied by this
means at the headquarters of the armies lately employed on the
Continent.

An artificial composition is sometimes used instead of lias.

Considerable quarries of this stone are wrought in Germany. It is also
found at Leixlip, near Dublin; in beds at Aberthaw, in Glamorganshire;
in Dorsetshire, and near Bath.

SULPHAT OF LIME.

192. _ALABASTER, or GYPSUM, is a kind of sulphat of lime, or of lime in
combination with sulphuric acid (24), which has a shivery and glittering
texture; and is of white colour tinged with grey or red, and sometimes
striped, veined, or spotted. When crystallized, the primitive form of
its crystals is a regular four─sided prism_ (Pl. II, Fig. 14.)

Being considerably softer than marble, this mineral is not capable of
receiving a good polish. From this circumstance it is, however, the more
easily worked. It is manufactured into chimney─pieces, columns, busts,
ornamental vases, and lamps; the latter of which transmit a soft and
pleasing light. Such is sometimes the transparency of alabaster, that it
has been employed for windows; and, at Florence, there is now a church
which receives its light through the medium of this substance.

The ancients, though acquainted with the art of making glass, had not
attained the knowledge of reducing it into thin transparent plates; and
frequently employed alabaster for windows. Of this stone the Temple of
Fortune, which was built by order of the Emperor Nero, was erected. It
had no windows whatever, and received only a soft kind of light through
its walls; appearing rather as if the light issued from the interior,
than that it was admitted from without.

The hot springs of St. Philip, which supply the baths of Tuscany, are so
strongly impregnated with alabaster, that artists take advantage of this
to obtain impressions of bas─reliefs, by merely exposing their moulds to
a current of the water until they become filled with the earthy deposit.
These impressions, when taken out, are found to be as hard as marble,
and are very beautiful. There are, in the British Museum, some casts of
medals formed from the water of these springs.

When alabaster is heated, it falls into a soft white powder, which, on
being mixed with water, absorbs it so rapidly, that if it be formed into
a paste, it dries and becomes hard in a few minutes. In this state it is
called _plaster of Paris_; and is employed for the making of statues,
casts, and other ornamental work, which, though of a beautiful white
colour, are very brittle. When mixed with coloured gummy or glutinous
substances, it yields plasters of different hues, and has the name of
_stucco_; and, in this state, is used for lining the walls and ceilings
of rooms. This plaster is much in request in the northern counties of
England, for the floors of dairies, store─rooms, granaries, and other
apartments; and, when properly formed, it constitutes a very smooth and
durable flooring.

The fine white varieties of gypsum are used as an ingredient in the
composition of earthenware and porcelain; and the glaze, or enamel, with
which porcelain is covered, has the purest gypsum for one of its
ingredients. Of late years this mineral has been advantageously employed
as a manure for fertilizing the soil.

Gypsum is found in Cheshire and Derbyshire, as well as in several parts
of the Continent. That which is imported into this country from Italy
and Spain is considered the best.

193. FIBROUS GYPSUM.—There is a variety of gypsum which has a somewhat
fibrous appearance, and which, when cut in a convex form, and polished,
reflects a light not much unlike that of the cats─eye (86). Hence it is
sometimes sold to ignorant persons for that stone. It has also been
imposed upon purchasers for the gem called moonstone (113). Fibrous
gypsum is cut into ear─pendants, crosses, beads for necklaces, and other
female ornaments; but its softness is such as to allow of its being
easily injured both by dirt and friction.

FLUAT OF LIME.

194. _FLUOR SPAR, or DERBYSHIRE SPAR, is a mineral formed by the
combination of lime with fluoric acid (27)._

_It sometimes occurs in a massive, and sometimes in a crystallized
state; the primitive form of its crystals being a regular octohedron_
(Pl. II, Fig. 5). _Its colour is usually bluish, green, yellow, whitish,
or a mixture of some of these._

When heated, this substance cracks, and shines brightly in the dark. But
if kept hot for some time, it ceases to be luminous, and this property
cannot be restored to it. If also two pieces be rubbed strongly
together, they become luminous in the dark.

From this spar are made several kinds of ornamental vases of
considerable size, columns, and toys, which, from being extremely varied
in their colours and appearance, and admitting of a high polish, are
very beautiful. When a piece of fluor spar is to be wrought into a vase,
or any similar article, it is first carved with a mallet and chisel into
a somewhat spherical form. It is then fixed to a turner’s lathe, and,
with great care, is formed into the shape that is required. When this is
complete, it has to be polished, which is done first with gritstone and
pumice (108), and lastly with emery (58) and putty. The lathes formerly
in use were worked by the foot; but those now adopted are worked by
machinery, the advantage of the more steady motion of which has been
that ornaments of much more delicate structure can now be formed than
before. The manufacture of articles from fluor spar gives employment to
a great number of industrious families in Derbyshire. This mineral
occurs in several parts of that county, where it has the name of _Blue
John_, and where it is obtained from caverns at a considerable depth
beneath the surface of the earth. It is also found in various countries
both of the European and American continents.

The acid produced from fluor spar is called _fluoric acid_ (27), and has
the peculiar property of corroding glass and flint, and consequently
cannot be kept in glass bottles. Artists, by means of fluoric acid, are
enabled to etch on glass, in the same manner as, with aqua fortis
(nitric acid), they do on copper. The process is sufficiently simple.
The glass is first a little heated, for the purpose of covering it
thinly over with wax; then, with a needle or other fine point the
drawing is to be made, by cutting through the wax to the surface of the
glass. The edges are next to have a little wall of wax raised upon them.
This done, the glass must be placed in an horizontal position, and
sifted over with fluor finely pounded; and lastly, a mixture of one part
of spirit of vitriol or sulphuric acid (24) with two or three parts of
water is to be poured gently upon it. The acid will be prevented from
running off by the wax; and, in the course of a little while, if these
be cleared away, the glass will be found corroded in all the lines along
which the needle passed.

The mode of obtaining fluoric acid for chemical purposes is, by pouring
sulphuric acid upon powdered spar in a leaden retort, and applying to it
a gentle heat. This acid should be used with great caution; for, when
applied to the skin, it instantly disorganizes it, and produces very
painful sores.


                            BARYTES FAMILY.

195. These minerals are sometimes called _ponderous earths_, and have
their name from a Greek word signifying _heavy_. They comprehend all the
combinations of barytes with acids.

When purified, they form a greyish white, porous substance, which is
easily reducible to powder; has no perceptible smell, but has a harsh
and more burning taste than lime, and changes the blues of vegetable
colours to green.

Although barytes is one of the most useful chemical tests that we are
acquainted with, it is not much employed in the arts, because, when
purified, it is found too expensive. It is capable of being made into a
very tenacious cement; and painters use a preparation that is made from
it as a white colour which will not change. This is sold in the shops
under the name of “Hume’s permanent white.” Barytes taken into the
stomach proves a virulent poison; yet a preparation of it is used in
medicine, and particularly for the removal of scrophulous complaints.
When finely pounded and mixed with oatmeal, _carbonat of barytes_ has
been found an efficacious poison for rats.

196. _SULPHAT of BARYTES is a mineral formed by the combination of
sulphuric acid (24) with barytes._

_It sometimes occurs in a state of powder, frequently in shapeless
masses, and often crystallized: the primitive form of its crystals being
a four─sided prism. It is not soluble in any other than sulphuric acid._

With us sulphat of barytes is of no use in the arts. The Chinese,
however, employ it as an ingredient in the composition of porcelain; and
it is said to form a good manure for clover fields.

_The_ BOLOGNA PHOSPHORUS, _or_ BONONIAN STONE, _a very remarkable kind
of barytes, has its name from being found near Bologna in Italy._ This
substance, when detached, is usually observed in roundish, flat,
kidney─shaped pieces, from about the size of a walnut to that of an
orange, which have a shining and somewhat fibrous texture within.

When the outer coat of this stone is washed away by heavy rains, it has
sometimes the appearance of burnished silver. An Italian shoemaker, in
the year 1630, deceived by this appearance, carried home several pieces,
hoping, by means of fire, to extract silver from them. But at the same
time that he was disappointed in this expectation, he was surprised by a
very unlooked─for phenomenon. All the pieces which he had thus attempted
to melt, when they were afterwards exposed to the light, became
themselves luminous. It is the singular property of the Bologna
phosphorus, after it has undergone calcination in a particular manner,
to become capable of imbibing so much light on exposure, for a little
while, to the light of the sun, or even to the flame of a candle, that
it will afterwards shine in the dark for an interval of from eight to
fifteen minutes, like a glowing coal, but without any sensible heat. The
light which it emits is sufficient to read by, provided the letters be
placed near it. If well prepared, the stone will retain this
extraordinary property for five or six years.

The preparation of it is thus conducted. Pieces of sulphat of barytes
are made red hot, for a few minutes, in a covered crucible placed in the
middle of a fire, and then left to cool. When cool, they are pounded in
a stone mortar, and sifted. The powder thus formed is made into a paste
with a little gum arabic, and divided into long cakes, or cylinders,
each about a quarter of an inch thick. These pieces are dried in a
moderate heat, and then, by degrees, are exposed to a more violent heat,
among charcoal, in a wind furnace. As soon as the coals of the furnace
are half consumed, it must be filled a second time, and the phosphorus
must be left undisturbed. When the coals are quite consumed the ashes
must be carefully blown off with a pair of bellows, and the phosphorus
will be found at the bottom of the grate.

────────────────────────────────────────────────────────────────────────




                            CLASS II.—SALTS.


                         ORDER I.—EARTHY SALTS.

                                ───────


                            ALUMINE FAMILY.

197. _ALUM is a substance of yellowish or greyish white colour, usually
opaque, but sometimes transparent. When purified, it consists of
slender, irregular, hair─shaped fibres, and has a sweetish, astringent
taste._

The alum of commerce is an artificial production from the different
kinds of stones which contain it. That called _Roman alum_, from its
being procured from the neighbourhood of Rome, is usually considered
preferable to the other sorts; but good alum of our own manufacture is
equal to it in quality. The Levant, or _Roche alum_, is said to have had
its name from the village of Rocca, the present Edessa, in Syria.

There is a famous alum mine at Tolfa, near Civita Vecchia, in Italy. The
alum is obtained from this mine nearly in a pure state; and it is so
extremely hard, that it can only be wrought by means of pickaxes, and
gunpowder. At Solfatara, near Naples, and in other volcanic countries,
an abundance of alum is found, in a state of efflorescence, from the
lava.

The alum of our own country is manufactured from a kind of slaty stone
which is found near Whitby, in Yorkshire. This manufactory was first
established about the conclusion of the sixteenth century, by Sir Thomas
Chaloner, who is supposed to have obtained his knowledge of the process,
from the alum works which had then lately been introduced into Germany
and Spain. The rock of _alum slate_, near Whitby, is supposed to be
nearly twelve miles in extent: and affords an abundant supply of alum.
The workmen tear open the rock; after which the different fragments are
loosened, in the form of slaty leaves or plates, that are of a dark grey
colour. To obtain the alum, a bed of fagots is formed from ten to twelve
feet in depth. By the side of this a scaffold is erected, which enables
the workmen to form a pile of mineral about fifty feet long, and forty
feet high. While this pile is forming, the fagots are lighted. By the
gradual operation of the heat, a calcination takes place, in consequence
of which the alum is afterwards rendered capable of being more easily
separated than it otherwise would be from the stone in which it was
contained, and from other extraneous matters that are combined with it.
After this, the mineral is washed in shallow vessels, so arranged that
the water may be poured from one into the other. By this process the
alum becomes suspended in the water, while all the earthy particles
subside to the bottom. The next operation is to evaporate the water
saturated with alum. This is done by boiling it in large leaden
caldrons, fixed, on cast iron bars, over a furnace. As soon as the
contents of the caldrons are brought to a proper state, they are drawn
off into casks, where the alum concretes into a mass. The hoops are then
taken off, and the alum is broken and left to dry; after which it is
packed in casks for sale.

Alum is an article of indispensable importance to dyers, not only on
account of its cleansing and opening the pores of the substances to be
dyed, and thus rendering them fit to receive the colouring particles,
but also from its more essential property of fixing the colours in such
manner that they cannot afterwards be washed out. By tanners it is in
great request for giving firmness to the skins after they have been
rendered flaccid in the lime─pits. It is employed in the manufacture of
paper, and by engravers, and other artists. In the making of candles,
alum is added to the tallow, to render it glossy, and to give it greater
firmness and consistence; and, mixed with cream, it aids the separation
of butter. It has a tendency to retard ignition. Paper soaked in alum
water does not easily take fire, and is thereby better fitted for the
preservation of gunpowder. Such paper is likewise used in the whitening
of silver, and the silvering of brass. It has been recommended that
ladies’ muslin dresses should be dipped in a solution of this substance,
for the purpose of rendering them less liable to catch fire. A solution
of alum also retards the putrefaction of animal substances, and affords
useful, as well as economical, means of preserving natural productions
that are imported from foreign countries. Alum is frequently mixed with
paste, to prevent its losing its tenacity by the absorption of moisture.
It is asserted that bakers occasionally use it as an ingredient in
bread, and that its presence may be discovered by thrusting a heated
knife into a loaf before it is cold: if free from alum, scarcely any
alteration will be visible on the blade, but if the contrary, the
surface, when cool, will appear slightly covered with an incrustation of
alum. A very important purpose to which alum may be applied is in the
purifying and sweetening of water that has become fetid and unfit for
use; from five to ten grains of burned alum, and double or treble that
quantity of pounded charcoal, will correct the fetor of a gallon of
water. Printers’ cushions, and the blocks used for the printing of
calicos, are rubbed with burned alum to remove any greasiness, which
otherwise would prevent the ink or colour from sticking. This substance
is also occasionally employed by surgeons to stop the bleeding of small
vessels, to corrode fungous or proud flesh, and for other purposes in
medicine.


                         198. MAGNESIA FAMILY.

This is a family of minerals which comprehends all the combinations of
magnesia with acids.

When freed from extraneous matters, magnesia is a powdery substance of
limpid white colour.

199. _EPSOM SALTS, or SULPHAT OF MAGNESIA, consist of magnesia in
conjunction with sulphuric acid (24)._

It is said that Epsom salts have been found in the Alps, and in
Switzerland, under a powdery form, and sometimes even in masses, or a
state of incrustation on stones and rocks. They are, however, chiefly
found dissolved in mineral waters, and particularly in those at Epsom in
Surrey, and Sedlitz in Bohemia. Their taste is bitter and unpleasant. So
little are they affected by exposure to the air, that the Abbé Haüy kept
some by him for more than twelve years without any sensible alteration.

These salts are much used in medicine, and are sometimes manufactured
from the waters of Epsom (290) and Sedlitz (289), but more frequently,
and in much greater abundance, from sea─water.

The _magnesia_ of the shops is prepared by dissolving Epsom salts in
water, and adding to the solution half their weight of potash (205). The
substance that sinks to the bottom is magnesia; and this, washed with a
sufficient quantity of water and dried, has the appearance of a light,
soft, and white powder, of insipid taste.

Magnesia is used in medicine, both in a simple state and when calcined
or burned. It is also employed in some chemical processes; and is in
considerable request in the manufacture of enamel and porcelain. If
putrid water be agitated with a small quantity of magnesia, it will lose
a considerable portion of its bad taste and smell.


                           200. SODA FAMILY.

Soda, like potash (205), is an extremely caustic alkali (42). It has a
greyish white colour, and agrees exactly with potash (205) in taste,
smell, and corrosive quality, but it is not so heavy.

In a mineral state soda has hitherto been found only in combination with
some acid.

Common salt (202) is a compound of soda with muriatic acid (29).

The soda of commerce is obtained from sea─water; and from the ashes of
different kinds of plants that grow on the sea─shores, but particularly
from that called _salsola soda_, which is found in great abundance on
the coasts of the southern parts of Europe; and from which it has its
name. It is sometimes called _barilla_, from the salsola soda being so
denominated in Spain.

This alkali is of essential use in the arts. When melted with flint or
sand, it forms glass, and answers much better for this purpose than
potash. In conjunction with oil and lime, it is employed in the
manufacture of soap; and it is used as a substitute for soap in the
cleaning and bleaching of linen, flannels, and worsted goods. If a weak
solution of soda be poured into foul bottles, or casks in which wine has
long been kept, it will cleanse them. It may also be successfully used
for the cleansing of vessels in which milk has become acid. Saddles,
bridles, or boot─tops, may be effectually cleaned by means of this
liquor, and restored nearly to their original colour and appearance.

The art of _soap─boiling_ may easily be illustrated by the following
experiment. Take a piece of quick─lime, slake it gradually by sprinkling
on it a sufficient quantity of water. When it is completely slaked, add
to it about twenty times its weight of water. To this mixture add two
parts, by weight, of common subcarbonat of soda, previously dissolved in
a sufficient quantity of water. Boil the whole for about half an hour,
strain it through a cloth, and boil it till so much of the water is
evaporated that a phial that will contain an ounce of water will hold
one ounce, seven pennyweights and a half, of this ley. Then mix in an
earthenware pipkin or basin, one part of the ley, with two parts of
olive oil. Place the mixture in a gentle heat, capable only of making
the liquor simmer, and allow it to simmer, stirring the liquor
continually, with a wooden stick, till, by letting a few drops of it
fall on a plate, the soap will be found to coagulate, and the water
become speedily separated from it. After which, pour out the contents
into a cup, and suffer it to cool.—Soap may also be prepared without
heat. If one part of the ley be mixed with two parts of olive oil, in a
glass or stone ware vessel, and the mixture be stirred, from time to
time, with a wooden spoon or spatula, it will become thick, and white;
in seven or eight days afterwards the combination will be completed, and
a white and firm soap will be obtained.

_White soap_ is formed of ingredients similar to those that have just
been mentioned. _Yellow soap_ is made with tallow, resin, and soda. Soap
may be formed by boiling shreds of woollen cloth with ley till the whole
has acquired a certain consistence. This kind of soap has been made, and
applied with success, in several manufactories in France.—The
combination of oil and other ingredients with potash (205), instead of
soda, affords what is called _soft soap_.

201. _NATRON, or CARBONAT of SODA, is a salt which consists of soda
(200) in combination with carbonic acid (26). It is massive, of greyish
colour, soluble in water, and has a disagreeable alkaline taste._

This salt is found in Egypt, on the surface of the earth, and
particularly near the margins of certain lakes called natron lakes. In
the summer season the water of these lakes is evaporated by the heat of
the sun, leaving a bed of natron generally about two feet in thickness.
This is broken with wedges and hammers; and packed up for sale in the
European markets. The waters of some of the lakes contain both common
salt and natron; and these, on evaporation, crystallize in successive
beds. Natron is found in considerable quantity under the form of an
efflorescence, on the surface of the earth, in the plains of Debreczin
in Hungary. It is likewise found in small quantity in the ashes of most
vegetables, but particularly in those of _salsoda_ and _salicornia_.

The ancient Egyptians are said to have made great use of natron for the
preservation of dead bodies, by macerating them in it for several months
previously to their being embalmed. Large quantities of this salt are
sometimes imported into England, by the East India Company’s ships, from
China, and other parts of the East. It is employed in the manufacture of
soap, and for the washing of linen. Glass─makers mix it with sand for
the formation of glass. On the continent it is administered as a
medicine in complaints of the bowels and liver. The ancients sometimes
employed a mixture of natron for soaking their seed corn, under an
impression, that, when afterwards committed to the earth, it would
thereby be rendered more fertile.

202. _COMMON SALT, or MURIAT of SODA, though found in some countries in
a solid and massive state, is for the most part an artificial
preparation from sea─water, and from the water of salt lakes and brine
springs. It consists of soda (200) in combination with muriatic acid
(29)._

Few productions, either natural or artificial, are in so much request as
common salt. It is used by the inhabitants of nearly all countries, for
correcting the insipidity of food. When applied in small quantities, it
accelerates the putrid fermentation; and, in this case, is considered to
aid digestion, by promoting the decomposition of the aliments. In larger
quantity it has a contrary effect, and tends to preserve organic
substances from corruption. Salt is used for glazing the surface of
coarse earthenware; and is employed in several processes of dyeing.

When this substance is dug out of the earth it has the appellation of
_rock salt_: and immense masses of it are found in different countries
of the world. The most considerable, as well as the most celebrated
_salt mines_, with which we are acquainted, are those about five miles
from Cracow, in Poland; and it is supposed that they contain more salt
than would be sufficient to supply the wants of the whole world for
several thousand years. On descending to the bottom of these mines, a
stranger is astonished to find a kind of subterraneous republic,
consisting of many families, who have their own peculiar laws and
polity. Here are likewise public roads, and carriages, horses being
employed to draw the salt to the mouths of the mine, where it is taken
up by engines. The horses, when once they are down, never more see the
light of day; and many of the people seem buried alive in this immense
abyss. Some are born there, and never stir out; others, however, have
occasional opportunities of breathing the fresh air in the fields, and
enjoying the light of the sun. The subterraneous passages or galleries
are very spacious; and, in many of them, chapels are hewn out of the
salt. In these are set up crucifixes, and the images of saints, before
which lights are kept continually burning. In some parts of the mine
huge columns of salt are left standing to support the rock. Its windings
are so numerous and intricate, that workmen have frequently lost their
way: the lights they carried have been burned out, and they have
perished before they could be found. The salt is taken from these mines
in blocks so large as, sometimes, to measure nine feet in length, four
feet in width, and two or three feet in thickness. In the year 1780, the
greatest depth to which the workmen had penetrated was about 320 yards,
and the mass of salt was considered to be in some places more than 240
yards thick, and to extend at least three leagues.

Near the town of Cardona, about fifty miles northwest of Barcelona, in
Spain, there is a mountain of salt, without cleft or crevice, 500 feet
high, and nearly three miles in circumference. In the province of
Lahore, in Hindostan, travellers have described a mountain of the same
mineral, not inferior to this in magnitude; and the elevated regions of
Peru afford rock salt at the height of 7000 feet above the level of the
sea.

At Northwich and Nantwich, in the county of Chester, there are salt
mines of great depth and extent. These are frequently visited by
travellers, and are found amply to repay the trouble and inconvenience
of descending into them. There are two principal beds of this substance;
the upper one is about forty─two yards below the surface, and twenty─six
yards thick. This was originally discovered about a century and a half
ago, in searching for coal. The lower bed has already been examined to
the depth of forty yards, without coming to the bottom; and it is about
the centre of this bed that the purest salt has been discovered. The
average depth of the cavity, formed by the workmen along the vein of
salt in the different mines, is supposed to be about sixteen feet. In
some of the mines, where pillars six or eight yards square are left to
support the roof, the appearance of the cavity is singularly beautiful:
and the effect is greatly increased when the mine is illuminated by
numerous candles fixed to the side of the rock. The scene so formed
would almost seem to realize the notion of the magic palaces of Eastern
poets. Some of the mines are worked in aisles or streets. The methods
employed in working out the salt offer nothing worthy of notice. Larger
masses are separated from the body of the rock, by blasting with
gunpowder; and are afterwards broken down with pickaxes, hammers, and
other instruments. The present number of mines in the vicinity of
Northwich is eleven or twelve, from which there are raised, on an
average, 50,000 or 60,000 tons of salt per annum. The greater part of
this quantity is exported to Ireland and the Baltic; and the remainder
is employed in Cheshire, and the adjacent counties.

Salt is also made from _brine springs_ in Cheshire, Cumberland,
Staffordshire, and Worcestershire; but the kind most commonly used in
England is that which is made from sea water, and has the name of _sea
salt_. The mode of manufacturing it is very simple. The water is first
pumped into shallow reservoirs of earth, called salt pans, or salterns.
In these it remains exposed to the sun until a certain proportion of the
water is evaporated, so as to leave it about seven times stronger than
in its original state. It is then conducted by another pump into flat
iron pans, eight or nine feet square, and as many inches deep. These,
being placed over a hot fire, the liquor or brine is boiled until nearly
all the remaining particles of water have passed off by evaporation, and
nothing is left in the pans but salt. This is thrown together into
proper vessels, for a few days, to drain, after which it is fit for use.

In some countries the whole evaporation is performed by the heat of the
sun; and, in extreme northern climates, where the sun would not have
sufficient power for the operation, a very different process is adopted.
The water is suffered to freeze in the salterns, and that portion of it
which continues uncongealed is so strongly saturated that it requires
only a moderate heat to evaporate the remainder of the water, and to
crystallize the salt.

_Bay salt_ is that which is produced from the evaporation of sea─water
by the heat of the sun only.

The inhabitants of Cardona, in Spain, make of the rock salt in their
neighbourhood various transparent articles, which they vend at a cheap
rate. These, which consist of small altars, figures of saints, crosses,
chandeliers, salt─cellars, &c. are as clear as crystal, and, to
appearance, as lasting. They are chiefly purchased by strangers as
curiosities, and are distributed over various parts of Spain and the
south of France.

The decomposition of salt furnishes the _muriatic acid_ (29), or _spirit
of salt_ of commerce. This liquid, which is much used in the arts, and
is in great request by chemists, is prepared, for common purposes, by
mixing one part of common salt with seven or eight parts of clay, and
distilling the mixture; or by distilling common salt and spirit of
vitriol or sulphuric acid (24), and receiving the product into a vessel
containing water.

It has been discovered that muriatic acid, in a state of gas, is an
excellent means of correcting putrid exhalations. In the year 1773, the
cathedral church of Dijon was so much infected by the corruption of
bodies which had been interred within its walls, that it was entirely
deserted. The professor of Chemistry at Dijon having been applied to for
assistance, placed, on a few burning coals, in the middle of the church,
a glass vessel containing six pounds of common salt. Upon this he poured
two pounds of sulphuric acid (24), precipitately withdrew, and shut all
the doors. The gas soon filled the whole cathedral. After twelve hours
the doors were thrown open, and a current of air was made to pass
through to remove the gas, which had entirely destroyed every putrid
odour.

The following has been recommended as an eligible mode of fumigating
rooms for the prevention of infectious disorders. Take six drachms of
powdered nitre (206), and six drachms of sulphuric acid (spirit of
vitriol); and mix them in a tea─cup, by adding to the nitre one drachm
at a time of the oil. During the preparation the cup must be placed on a
piece of heated iron, and the mixture stirred with a tobacco pipe or
piece of glass. As soon as the fumes arise, the cup must be moved about
to different parts of the room or house that are to be fumigated.

203. _GLAUBER SALT, or SULPHAT of SODA, is a salt which consists of soda
(200) in combination with sulphuric acid (24). It occurs in an
efflorescent or powdery state, on the borders of salt lakes; or, more
commonly, in a state of solution, in certain mineral waters._

This salt, which was originally discovered by a German chemist whose
name was Glauber, has a nauseously bitter and saline taste. It is found,
in an efflorescent state, on meadow ground at Eger, in Bohemia; and on
the walls of old galleries in mines, at Grenoble, in France. It is also
abundant in the ashes of some kinds of vegetables, especially of sea
weeds. The waters of the Mediterranean yield a great proportion of it;
and the Glauber salt used for commercial purposes is chiefly prepared
from sea─water, or by decomposing common salt, in order to procure
muriatic acid (29). It may also be obtained by saturating soda with
sulphuric acid (24).

The use of this salt in medicine is well known; and, in some countries,
it is employed as a substitute for soda (200), in the manufacture of
white glass. It ought to be kept in well─corked bottles, as otherwise
the crystals soon fall into powder.

The following is a pleasing experiment, which shows a singular and
almost instantaneous crystallization of Glauber’s salt. Dissolve this
salt by adding portions of it gradually to water kept boiling until the
water will dissolve no more. Pour the solution, whilst boiling, into
common medicine phials previously warmed, and immediately cork them. Set
the phials in a quiet place without shaking them. The solution, when
cool, will remain perfectly fluid till the cork is taken out; but the
moment this is done, and the air is admitted, it will begin to
crystallize on its upper surface, in fine satin─like crystals, which
will shoot downward, like a dense white cloud. In this act so much heat
becomes evolved as to make the phial feel sensibly warm to the hand.
When the crystallization is complete, the whole mass generally becomes
so solid, that, on inverting the bottle, not a drop of it will fall out.
If the crystallization should not immediately ensue on opening the
phial, this may instantly be effected by dropping into it a minute
crystal of the same salt. The experiment may be exhibited any number of
times afterwards, by merely placing the phial in boiling water, till the
salt it contains be again completely liquefied; and letting it stand, as
before, to cool.

204. _BORAX is a salt composed of boracic acid (28) and soda (200), and
is imported chiefly from the East Indies, in the form of a brownish
grey, impure, shapeless salt, of sweetish taste; or in detached
prismatic crystals, each about an inch in length._

Although borax has long been known as an article of traffic, there is
scarcely any production with the origin of which we have been, till
lately, less acquainted. It is found in a native, though impure state,
in a mountain lake, situated about fifteen days’ journey from the
capital of Thibet in the East Indies. This lake is so encompassed with
hills as to have no stream either falling into it or flowing from it.
The water is salt to the taste, and contains both borax and common salt;
and the edges and shallow parts are covered with a stratum of this
substance, which is dug up in considerable masses for exportation. It
has here the name of _tinkal_, and is usually brought into Europe
enveloped in a kind of fatty substance. The mode of refining it was for
a long time kept, by the Dutch and Venetians, amongst those secrets
which a want of sufficient research alone prevented from being generally
known. When refined, it is called _borax_.

The uses of borax are numerous. It is employed as a flux for metals,
being found to produce a more perfectly limpid fusion than any other
substance. For the same reason it is made an ingredient in the finest
kinds of glass, and particularly in some of the coloured glass pastes
which are manufactured in imitation of gems. But its chief use is to
jewellers and goldsmiths, to facilitate the soldering of gold and
silver. Borax is also used in medicine.


                          205. POTASH FAMILY.

Potash is an alkaline substance (42), of white colour, and of smell
somewhat resembling that which is perceived during the slaking of
quick─lime (137). It is extremely corrosive, and remarkably acrid to the
taste.

In a mineral state it is found only in combination with nitric acid
(30).

Potash principally exists under the form of a salt, in vegetable
substances; and is obtained by burning them, afterwards repeatedly
washing the ashes with water, and then filtering and evaporating these
to dryness. The appellation of potash was given to this salt from its
having formerly been prepared in large iron pots.

The uses to which it is applied are numerous. In chemistry it is
employed for a variety of purposes; and also in many arts and
manufactures, in scouring, washing, bleaching, dyeing, glass─making, and
several others. Its corrosive property is such that it is often used by
surgeons under the name of _potential cautery_, to open abscesses, and
to destroy useless or hurtful excrescences.

=Potash=, after it has been made red hot, is rendered whiter and more
pure. In this state it has the name of pearl ash.

206. _NITRE, or SALTPETRE, is a salt which consists of potash in
combination with nitric acid (30)._

_Its colour is whitish or limpid; and it does not liquefy by the action
of the air. It is usually observed in the form of fine capillary
crystals, though it is sometimes found in a massive state. When pure, it
crystallizes into six─sided prisms (Pl. II, Fig. 15) which have a
rectangular base. It is denominated by chemists_ nitrat of potash.

Nitre is found incrusted on the surface of the earth, in some parts of
India, Africa, and Spain, and, in such abundance, as to admit of being
swept off at certain seasons of the year, twice or three times a week.
In our own country it not unfrequently occurs in a state of white
efflorescence, on old plaster walls that are sheltered from rain. Nitre
is also produced in stables and cart─houses, from the mixture of animal
and vegetable substances in a state of putrescence.

Many kinds of plants, which grow in soils favourable to the production
of it, contain nitre: this is particularly the case with pellitory,
borage, and the large sunflower.

Immense quantities of nitre are annually required for the purposes of
war. From its constituting one of the most important substances in the
composition of gunpowder, it has been found necessary to adopt
artificial modes of procuring it. In several districts of the East
Indies there are places called saltpetre grounds. From these large
quantities of the earth are dug, and put into cavities through which
water is passed. This brings away with it the salt which the earth
contains, and which is afterwards separated from the water by boiling.
The East India Company, for more than a century past, has been under
engagements to import into this country, and supply the board of
ordnance, for his Majesty’s service, with 500 tons of nitre annually, at
given rates and prices in times of peace and war.

In France this article is obtained in what are called _nitrières_, or
nitre beds. These consist of the refuse of animal and vegetable
substances, which undergo putrefaction, mixed with calcareous and other
earths; and the nitre is obtained from them by water, as
above─mentioned.—The principal requisites for the formation of nitre are
said to be lime, animal and vegetable matters, heat, and an open, but
not too free communication with dry atmospheric air.

The discovery of _gunpowder_ has completely changed the modern art of
war. The earliest notice that has occurred respecting the use of this
article in Europe is, that it was employed in the wars of Germany,
somewhat before the year 1373. It is said, however, to have been known
in China long anterior to that period. Its component parts are nitre,
charcoal, and sulphur, in the proportion of seventy─six, fifteen, and
nine parts, in every hundred. These ingredients are first reduced to a
fine powder separately, and then mixed with water, so as to form a thick
paste. After this has dried a little, it is placed upon a kind of sieve
full of small holes, through which it is forced. By this process it is
divided into grains, the size of which depend of course upon the size of
the holes through which it has been squeezed. It afterwards undergoes
some other operations before it is ready for use.

Nitre is frequently administered in medicine; and it is used very
extensively in different arts. A mixture of equal parts of nitre and
tartar, burned together in a crucible, forms what is called _white
flux_, which is used for melting and reducing different kinds of
metallic substances. And a mixture of one part of nitre and two parts of
tartar burned in the same manner forms what is called _black flux_.
Nitre possesses antiseptic qualities in a considerable degree, whence it
is much used, in conjunction with common salt and bay salt, for the
preserving of animal food from putrefaction.

_Aqua─fortis_, or _nitric acid_ (30) as it is denominated by chemists,
is prepared from this mineral. The mode of obtaining it in large
manufactories is by distilling a mixture of nitre and clay in glass or
stone retorts, each capable of containing seventy or eighty pounds’
weight of this mixture. But the acid thus procured being weak and
impure, chemists, for nicer purposes, generally prepare it by
distilling, in a glass apparatus, a proportion of three parts of nitre
and one of sulphuric acid (24). The uses of aqua─fortis are various and
important. All kinds of metals, except gold and platina, are capable of
being dissolved in it. Hence, among other uses, it is employed by dyers,
for dissolving tin, and forming with madder a scarlet colour; and, by
hatters, for dissolving mercury (228) for some processes in the
preparation of hats. Jewellers use it for several purposes.


                            AMMONIA FAMILY.

207. _SAL─AMMONIAC, or MURIAT OF AMMONIA, is a salt compounded of
ammonia and muriatic acid (22). It is occasionally found in a state of
powder, sometimes in a massive form, and sometimes in very irregularly
shaped crystals, the primitive form of which is an octohedron (Pl II,
Fig. 5). It is, however, more frequently an artificial production from
the soot of burned animal matter._

The name of sal─ammoniac was acquired by this substance from its having
been found by the ancients in great abundance amongst sand near the
temple of Jupiter Ammon, in Africa. It is at present found in Persia;
and, accompanying sulphur, amongst volcanic matter near Mount Vesuvius.

This salt was formerly imported from Egypt in the form of conical
loaves, or of round cakes, which were convex on one side and concave on
the other; but it is now made in Europe, by burning at the same time
soot, bones, oil, and salt. The deposit formed by the vapour consists of
sal─ammoniac, in conjunction with other substances, which are separated
from it by a subsequent process. When good, it is white, transparent,
and dry within; and externally of yellowish grey, or blackish colour.

Sal─ammoniac is applied to many useful purposes. Occasionally it is used
in medicine. A considerable portion of it is consumed by dyers, to give
brightness to some of their colours. It is also employed in the assay of
metals, to discover the presence of iron; and having the property of
rendering lead brittle, is sometimes used in the manufacture of shot. By
coppersmiths and tinners it is used for cleansing the surface of the
metals which they are about to cover with tin. In certain manufactories
sal─ammoniac is mixed with tobacco, to give that article, or the snuff
that is made from it, additional stimulant properties. Sal─ammoniac
dissolved in nitric acid (30) forms the fluid named _aqua─regia_, which
is employed in the solution of gold.


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                       ORDER II.—METALLIC SALTS.


                             SALTS OF IRON.

208. _GREEN VITRIOL, IRON VITRIOL, or COPPERAS, is a mineral salt formed
on a decomposition of pyrites (236) by the moisture of the atmosphere.
It is also called SULPHAT OF IRON._

_Its colour is bright green, and its taste very astringent; a solution
of it in water dropped on oak bark instantly produces a black spot._

Although copperas is occasionally found in grottoes, caverns, the
galleries of mines, and other places; yet, being much in request by
dyers, tanners, and the manufacturers of ink, it is artificially
prepared from pyrites. This mineral being moistened and exposed to the
air, a crust is formed upon it, which is afterwards dissolved in water;
and from this the crystals of vitriol are obtained by evaporation.

The principal use of vitriol is in dyeing woollen articles, hats, and
other manufactures, black. It is the basis of ink, and is used in the
manufacture of Prussian blue. If it be reduced to powder by the action
of fire in a crucible, and mixed with powder of galls, it forms a dry
portable ink. Sulphuric acid (24) may be obtained from this kind of
vitriol by distillation. The residue, after the process is completed, is
used as a red paint; and when washed, is employed for the polishing of
steel.

                            SALTS OF COPPER.

209. _BLUE VITRIOL, or SULPHAT OF COPPER, is a blue salt formed by a
combination of copper with sulphuric acid (24)._

This substance, though sometimes found in a state of concretion, or in
the form of powder disseminated over the surface of stones that have
been in contact with water impregnated with it, is more frequently an
artificial preparation obtained from evaporating the water which runs
through copper mines. In the mines of Neussol, in Hungary, at the depth
of 380 feet beneath the surface of the ground, are several vats, placed
at different distances, for the purpose of collecting the water
impregnated with copper, and which flows into them through a kind of
gallery above. From this water the vitriol is afterwards separated by
evaporation. A process somewhat similar is pursued in our own country.

In the principal blue vitriol manufactories established in France, the
operation is thus carried on. Pieces of copper are first dipped into
water, and their surface, while wet, is covered with a stratum of
powdered sulphur. The copper thus prepared is put into an oven, and
heated to redness. After some time, it is taken out, and, while hot, is
plunged into a vessel filled with water. These operations are repeated
several times, till the whole of the copper is dissolved, and the water
becomes loaded with vitriol. Thus saturated, the water is placed over a
fire till all the fluid particles are dissipated, and the vitriol alone
is left.

Blue vitriol is used by artists and manufacturers in various ways. It is
employed in dyeing: and enters into the composition of black colours, to
which it gives depth and solidity. Blue feathers are stained by plunging
them into a hot solution of it. The beautiful grass─green colour of the
shops, called _mineral green_, is made from blue vitriol; and
fowling─pieces and tea─urns are browned by washing them with a
preparation of it.

                             SALTS OF ZINC.

210. _WHITE VITRIOL, or SULPHAT OF ZINC, is a whitish, yellowish, or
greenish white salt, formed by a combination of zinc (241) with
sulphuric acid (24)._

Although the white vitriol that is used in commerce is chiefly an
artificial preparation, this salt sometimes occurs in a natural state,
in mineral repositories that contain blende (241); and it appears to be
formed by a decomposition of that ore. It is found at Holywell, in
Flintshire, and in some parts of Cornwall.

When white vitriol is artificially prepared, the blende is roasted, and
thrown, while red hot, into a vessel filled with water; in which it is
allowed to remain about eighteen hours. This process is repeated several
times; and, after the solution has become clear, it is removed into
leaden vessels, and the water is evaporated by means of heat. On
cooling, it crystallizes. After this the crystals are melted in a copper
vessel, and the surface of the solution is skimmed with a hair sieve. It
is then poured into a wooden vessel, and stirred till it becomes cool,
and acquires a sufficient degree of consistence, when it is formed into
loaves for sale. In this state it has the appearance and colour of
refined sugar. White vitriol is chiefly manufactured in Germany.

It is used in medicine; and is employed in great quantities by
varnishers, to make their oil varnishes dry more readily than they
otherwise would. A fine white colour, called _zinc─white_, which is more
durable than white lead, is prepared from it. Dyers use a considerable
quantity of white vitriol to render deeper the colours produced by
madder, cochineal, and other substances.

A pleasing experiment is made by mixing in a phial a small quantity of
solution of white vitriol with a little liquid ammonia. Though each of
the fluids is transparent when separate, yet the zinc will now be
immediately precipitated in a white mass; and, what is peculiarly
deserving of remark, if then shaken, it will almost as instantly be
re─dissolved.


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                        CLASS III.—COMBUSTIBLES.

                                ───────


                            SULPHUR FAMILY.

211. _COMMON SULPHUR, or BRIMSTONE, is a yellow, dry, and brittle
substance, which, in burning, yields a suffocating fume: the smell of
this, under the denomination of_ sulphureous, _is well known._

_Sulphur is found in a pure or native state in nearly all volcanic
countries: it is about twice as heavy as water; and is sometimes
crystallized in the form of octohedrons, whose bases are rhombs. It
exists abundantly in a state of combination with several metallic
substances, and is also formed in putrid animal remains._

A great proportion of the sulphur which is used in commerce is obtained
by the process of roasting copper, and other ores, previously to their
being smelted. It passes off in the form of vapour, and, on being
received into chambers constructed for the purpose, is there deposited
in a powdery state. The substance thus formed is the _flour of sulphur_
of the shops. It is afterwards melted in large pans, and cast in wooden
tubes, to make the hard, or _roll brimstone_. Nearly all the sulphur
used in France comes from the Solfatara of Italy. This volcanic country
every where exhibits indications of the agency of subterraneous fires.
Nearly the whole ground is bare and white; and, in every part, is warmer
than the atmosphere during the greatest heat of summer. A sulphureous
vapour is constantly emitted from the earth, and sulphur is condensed in
various parts, and in great abundance. This is collected, packed in
casks, and exported to Marseilles, where it undergoes certain
preparations that are necessary towards purifying and rendering it fit
for sale.

A considerable quantity of sulphur is employed in the composition of
gunpowder (206). Its readiness of taking fire is the reason of its being
employed in the making of matches. Sulphur gives a blue colour to
artificial fire─works. Its vapour is used for the whitening of silk and
wool, and also for the bleaching of straw used for making ladies’ hats.

Modellers employ sulphur to make moulds for various kinds of casts; and
artists are enabled, by means of it, to take sharp and beautiful
impressions of medals and engraved stones. The mode of doing this is
very simple. The sulphur is put into an earthen vessel called a
crucible, and placed on a hot fire. It soon melts; and if kept some time
over the fire, becomes thick and dark─coloured. When poured into water
in this state, it is as soft as wax. It may now be easily worked between
the fingers into any given form: and, if pressed upon a seal or engraved
stone, will be found to retain a perfect impression of it. It is this
property of sulphur of which Mr. Tassie, of Leicester─fields, London,
has availed himself, to furnish extremely elegant impressions of many
antique gems.

Sulphur was much used by the ancients in medicine; and it is now
occasionally administered both as an external and internal remedy. The
compounds formed from it are employed to considerable extent in various
processes of dyeing and calico printing. Many of the mineral waters,
those, for instance, of Harrowgate (299) and Moffat (300), are indebted
to sulphur for their most valuable qualities.

This substance has the property of becoming electric by rubbing. On
exposure to a gentle heat, it melts; but if the heat be increased, it is
entirely consumed, and passes off in vapour. When ignited, and the
combustion is slow, it burns with a suffocating and acid fume, and blue
flame; but when the combustion is quick it burns with a white and vivid
flame. If exposed to a sudden, though gentle heat, by holding it, for
instance, in a hand when that is warm, it will sometimes break in pieces
with a crackling noise.

It is a remarkable circumstance, that, if a bar of iron be heated to
perfect whiteness, and then touched with a roll of sulphur, the two
bodies combine, and drop down together, in a fluid state, forming what
is called _sulphuret of iron_, a compound of the same nature as iron
pyrites (236). A piece of iron rolled out very thin may be apparently
melted in the hand, by putting it, when heated to whiteness, upon a
thick piece of solid sulphur. It is, however, necessary, that this
experiment be performed with great care; and under a chimney, or in a
place where there is a current of air, to carry off the suffocating
vapour.

Useful as sulphur is, in various ways, its most important application is
supposed to be for the production of _sulphuric acid_, or _spirit of
vitriol_ (24). One mode in which this acid is obtained for the purposes
of commerce, is by burning a mixture of sulphur and nitre (206) in large
chambers lined with lead. In this process the nitre supplies a
considerable portion of oxygen (21) to the sulphur, and the air of the
atmosphere furnishes the rest. Thus a substance which, in a natural
state, is one of the mildest that we are acquainted with, is by this
operation converted into a corrosive and dangerous, though useful fluid.
Its taste is strongly acid: and, when applied to animal or vegetable
substances, it soon corrodes, and destroys their texture.

The properties of sulphuric acid have rendered it extremely valuable for
numerous purposes, both in the arts and in the laboratory. It has been
long employed by chemists, as one of their most useful and frequent
agents.

The fluid that is put into the bottles for procuring _instantaneous
light_ is no other than sulphuric acid; and it is poured among filaments
of asbestos (which it will not corrode), for the same purpose as ink is
sometimes poured upon cotton. The matches are slips of wood dipped in a
mixture of equal weights of sugar or charcoal powder, and what the
chemists call hyperoxy─muriat of potash. These are to be rubbed together
in a mortar, but with great care, as by strong friction the mixture is
apt to explode. To obtain a light, nothing farther is requisite than to
dip a match, thus formed, into a bottle containing the acid.


                            BITUMEN FAMILY.

212. _NAPHTHA, or ROCK OIL, is a yellow or brownish bituminous fluid, of
strong penetrating odour, somewhat greasy to the touch, and so light as
to float even on spirit of wine._

_By exposure to the air, the consistence of naphtha is increased, and it
passes into petroleum (213)._

There are copious springs of naphtha at Baku, on the shore of the
Caspian Sea; and also in some parts of Italy, particularly at
Monte─Chiaro, near Piacenza. At Pitchford, in Shropshire, extensive
strata or beds of sandstone are saturated with this mineral fluid, which
is obtained from the stone by distillation, and is sold, as a remedy
against sprains and rheumatism, under the name of _Betton’s British
oil_.

By the Persians and Russians naphtha is used internally as a cordial. On
the shores of the Caspian it is burned in lamps, instead of oil; and, in
some parts of Italy it is employed in the lighting of churches and
streets. When mixed with certain vegetable oils, it forms an excellent
varnish.

It is the property of naphtha to take fire on the approach of a light,
and to burn with great readiness and a white flame, leaving scarcely any
residuum. The town of Broseley, in Shropshire, was formerly celebrated
for a _burning spring_, which was first discovered in the month of June,
1711. Its original issuing from the ground was announced by a terrible
noise in the night, which awakened several persons who lived near the
spot. Some of these, on going out to ascertain the cause of the alarm,
perceived, about two hundred yards from the river Severn, an
extraordinary shaking of the earth, and a little bubbling of water
through the grass. On digging round the spot, the water sprang up to a
great height, and a candle which one of them held in his hand, set it on
fire. This circumstance excited great curiosity; and many persons, from
different parts of the adjacent country, came to visit what was called
the “burning well.” To prevent this spring from being destroyed, an iron
cistern was placed upon it, with a small hole in the cover, through
which the water might be viewed. When a lighted candle was put into this
hole, the water immediately took fire, darting and flashing in a violent
manner, much in the same way as spirits do in a lamp, but with greater
agitation. It would sometimes burn for forty─eight hours successively,
and without any sensible diminution: and a tea─kettle, full of water, by
being placed upon the hole, has been made to boil in nine minutes. In
1747, this spring had been lost for many years; but another was shortly
afterwards discovered, the issuing of which was announced by a rumbling
noise under ground, similar to that which had been formerly heard. This,
however, also disappeared in the year 1756, by the sinking of a coal─pit
in the neighbourhood.

213. _PETROLEUM, or MINERAL OIL, is a fluid bitumen, of somewhat greater
consistency than naphtha: of black, brown, or sometimes dingy green
colour._

_By exposure to the air it assumes the consistence of tar, and is then
called MINERAL TAR (214)._

This substance exudes spontaneously from the earth, or from clefts of
rocks, and is found in nearly all countries, particularly in the East
Indies, Italy, France, Spain, Germany, and England. In the neighbourhood
of Rangoon, in Pegu, there are several hundred wells of petroleum. These
are of square form, of considerable depth, and each lined with cassia
wood staves. The oil is drawn from them pure, and in a liquid state, and
is conveyed thence in small jars. The whole annual produce of this
district is estimated at more than 400,000 hogsheads.

At Colebrook Dale, in Shropshire, there is a spring of petroleum. This
was discovered at the depth of about thirty yards beneath the surface of
the earth, in digging an archway for the conveying of coals from a very
deep pit. The petroleum was at first found to ooze from between the
crannies of the rock, but it soon afterwards poured forth in a
considerable stream. The utility of this fluid having been made known,
large iron pipes were formed from the spring into pits sunk for the
purpose of receiving it. From these pits it is conveyed into immense
caldrons, where it is boiled until it attains the consistency of pitch.
Since the first discovery of this substance, three different springs of
it have broken out. One of these is near the celebrated iron bridge; and
the fluid that issues from it is almost pellucid, but, at the same time,
is thicker than treacle.

Petroleum easily takes fire, and, in burning, yields a strong, sharp,
and somewhat unpleasant odour; and a thick and disagreeable smoke. In
cold weather it congeals in the open air.

In Pegu, and other parts of the East, petroleum is used in place of oil
for lamps. Boiled with a species of resin, it is employed for painting
the timber of houses, and covering the bottoms of boats and other
vessels. In the latter respect it is considered to be particularly
efficacious, by protecting the timber from the attacks of marine worms.
It is also used by the inhabitants of eastern countries as a lotion in
cutaneous eruptions, and as an embrocation in bruises and rheumatic
affections. The ancient Egyptians used it in the embalming of dead
bodies. In some countries lumps of earth are soaked with petroleum, and
are employed as fuel.

214. _MINERAL TAR, or BARBADOES TAR, is a fluid kind of bitumen,
somewhat thicker than petroleum, and nearly of the consistence of common
tar. It is viscid, of a black, brownish black, or reddish colour._

_In burning its smell is disagreeable, but less pungent than that of
most other kinds of bitumen. Its weight is somewhat greater than that of
water._

In the West Indies, where this substance is principally found, it is
applied to many of the purposes for which the preceding species is used;
but its principal repute has been obtained from its being thought useful
in disorders of the breast and lungs, though this application of it is
considered very improper. It is likewise used as an external remedy in
paralytic disorders.

215. _ELASTIC BITUMEN, or MINERAL CAOUT─CHOUC, has a strong resemblance
to Indian rubber. In some instances it is elastic, and so soft as to
adhere to the fingers, and in others brittle, and so hard as nearly to
resemble asphalt (216)._

_Its colour is yellowish, reddish brown, or blackish. One kind of this
mineral, when fresh cut, nearly resembles fine cork, both in texture and
colour._

This extraordinary substance, which will expunge the marks of black lead
in the same manner as Indian rubber, was first discovered, about the
year 1786, in cavities of the lead mine of Odin, near Castleton, in
Derbyshire, and it has not hitherto been found elsewhere. Elastic
bitumen appears to be a peculiar modification of petroleum, in its
passage to asphalt: and probably owes its elasticity to its cellular
texture, and to the moisture with which it is combined.

216. _ASPHALT, or SOLID BITUMEN, is a brittle substance, of black or
brownish black colour, and of consistence somewhat harder than pitch._

_It has nearly the same weight as water, is smooth to the touch, does
not stain the fingers, and has little or no smell unless it be rubbed or
heated. When heated, it melts, swells and inflames; and, if pure, burns
without leaving any ashes._

The ancients were well acquainted with this substance, which is nothing
more than mineral tar (214) in an indurated or hardened state. It is
found on the surface of volcanic productions, and floats, in solid
pieces, and in considerable abundance, on the Asphaltic Lake, in Syria,
which has thence received its name. This lake is also called the Dead
Sea, from a notion that the odour arising from the asphalt destroys even
birds which fly over it: Maundrell, however, states that this is not
true, as he saw several birds fly about and over it, without
experiencing the slightest injury.

Asphalt is also found near ancient Babylon; and there is reason to
suppose that the mortar so celebrated amongst the ancients, and with
which the walls of Babylon and of the Temple of Solomon were cemented,
was nothing more than a preparation of asphalt. We are informed by
Herodotus that a composition of heated bitumen, mixed with the tops of
reeds, was used by the ancients as a cement. This account is confirmed
by modern travellers, who assert that the remains of buildings have been
discovered in which bitumen was formerly thus employed. It is presumed
to be the same substance which, in our translation of the Old Testament,
is called pitch, and which was used by Noah, as an exterior and interior
coating of the ark; by the mother of Moses as a coating for the little
vessel in which he was exposed; and on various other occasions.

As an article of modern utility, it is to be remarked that the Arabians
dissolve asphalt in oil, and, with the mixture, smear their horse
harness, to preserve it from the effects of weather, and the attacks of
insects. In a state of solution it is applied, in several eastern
countries, as a covering for timber and the bottoms of ships. It is
occasionally used in the cleansing and healing of ulcers, and other
sores. In France it is manufactured into a substance which is in
considerable request for greasing the wheels of carriages. It is used by
the makers of watch─dials, who mix it with lamp black, and oil of
turpentine; but its chief use is as an ingredient in certain varnishes,
and particularly in the varnish used by copper─plate engravers. It is
frequently adulterated by a mixture with common pitch; but this is
easily discovered by the smell.

Besides the countries and places already mentioned, asphalt is found in
several parts of America, in the island of Trinidad, in the province of
Neufchatel, and many parts of the Continent of Europe.


                              COAL FAMILY.

217. The component parts of coals are principally carbon or charcoal
(48), and bitumen (216).

Some kinds of coal are laminar, and others compact. They in general burn
freely, with a bituminous odour, and leave a considerable residuum.

This invaluable mineral is found in beds, or strata, frequently betwixt
clay slate (257) and sandstone (267), and seldom betwixt those of
limestone (140). It chiefly occurs in the northern hemisphere,
particularly in countries which lie nearly in the same latitudes with
Great Britain; in Siberia, Germany, Sweden, France, Canada, and
Newfoundland; and in some of the northern parts of China. It is stated
to be abundant in New Holland; but we have no distinct account of coal
in the continent of Africa. No fewer than seventy different kinds of
coals are brought to the London market, the value and prices of which
greatly differ. Of these the coals called _Wall’s─end_, from the name of
the pit, near Newcastle, whence they are obtained, usually bear the
highest price.

218. _COMMON COAL, or PIT COAL, is of black colour, and has generally a
slaty structure and foliated texture._

_When handled it stains the fingers; and when burnt it cakes more or
less during combustion. Its component parts are usually charcoal (48)
and bitumen (216), with a small portion of clay, and sometimes with
pyrites, or sulphat of iron (236). What is called slaty coal contains a
greater portion of clay than other kinds._

Some foreign writers have ascribed the great wealth possessed by this
country to the coals which are here produced in such abundance, and
which facilitate, in a very essential degree, nearly all its
manufactures, and consequently are a means of promoting its commerce to
an extent which is possessed by few other countries. All our great
manufacturing towns, Birmingham, Sheffield, Leeds, Glasgow, &c. are
situated either in the midst of coal districts, or in places to which
coals are conveyed, with little expense, by canal carriage.

Coals are principally obtained from the neighbourhood of
Newcastle─upon─Tyne, Sunderland, and Whitehaven. The particular places
whence they are obtained have the name of _collieries_, and the mines
from which they are dug are called _pits_. The deepest of these are in
Northumberland, and are worked at more than 900 feet below the surface
of the earth. At Newcastle there is a coal─pit near 800 feet in depth,
and which, at that depth, is wrought five miles horizontally, quite
across, and beneath the bed of the river Tyne, and under the adjacent
part of the county of Durham. At Whitehaven the mines are of great
depth, and are extended even under the sea, to places where there is
above them sufficient depth of water for ships of great burthen, and in
which the miners are able sometimes to hear the roaring of the water. On
the contrary, in some parts of Durham the coal lies so near the surface
of the earth that the wheels of carriages lay it open, and in such
quantity as to be sufficient for the use of the neighbourhood.

The beds of coal are of various thicknesses, from a few inches to
several feet; and in some places, it is found advantageous to work them
at a very great depth, although their thickness does not exceed four or
five feet. The thickest bed of English coal, of any extent, is that of
the main coal in Staffordshire, which measures about thirty feet. In
many places there are several beds above, and parallel to, each other,
separated by strata of slate, sandstone, and other minerals. Coal is
never found in chalk, and very rarely in limestone.

At Whitehaven, the principal entrance to the coalmine, both for men and
horses, is by an opening at the bottom of a hill, through a long passage
hewn in a rock. This, by a steep descent, leads to the lowest bed of
coal. The greatest part of the descent is through spacious galleries,
which intersect other galleries; all the coal having been cut away,
except large pillars, which, in deep parts of the mine, are three yards
high, and about twelve yards square at the base, such great strength
being there required to support the ponderous roof. There are three
distinct and parallel strata of coal, which lie at a considerable
distance above each other, and which have a communication by pits that
are sunk between them. These strata are not always regularly continued
in the same plane. The miners occasionally meet with veins of hard rock,
which interrupt their further progress, and, at such places, the earth,
on one side of the vein, appears to have sunk down, while that on the
opposite side has its ancient situation. These breaks the miners call
_dykes_ (4). When they come to one of them, their first care is to
discover whether the coal, in the part adjoining, be higher or lower
than that in which they have been working; or, to use their own terms,
whether it be cast down or cast up. For this purpose they examine
attentively the mineral strata on the opposite side, to see how far they
correspond with those which they have already passed through. If the
coal be cast down, they sink a pit to it: but if it be cast up, the
discovery of it is often attended with great labour and expense.

In general the entrance to coal mines is by perpendicular shafts, and
the coals and workmen are drawn up by machinery. As the mines frequently
extend to great distances, horizontally, beneath the surface of the
earth, peculiar care is necessary to keep them continually ventilated
with currents of fresh air, for the purpose, not only of affording to
the workmen a constant supply of that vital fluid, but also to expel
from the mines certain noxious exhalations which are sometimes produced
in them.

One of these, denominated _fire damp_, is occasioned by the generation
of hydrogen gas, or inflammable air (45). This gas, when mixed with the
common air of the atmosphere, explodes, with great violence, on the
approach of a lighted candle, or any other flame; and has, at different
times, occasioned the loss of many valuable lives. It is a singular
circumstance, that although it is immediately set on fire by a flame,
yet it cannot be kindled by red hot iron, nor by sparks produced from
the collision of flint and steel. Hence a machine was, some years ago,
adopted in the mines near Whitehaven and Workington, in which a wheel
formed of steel, and in shape somewhat like that of a razor─grinder, was
turned round with very rapid motion against a series of flints, and in
such manner as to yield to the miners sufficient light to carry on their
work in places where the flame of a candle would occasion the most
dreadful explosions. Sir Humphrey Davy has lately invented, for the use
of mines where this gas is prevalent, what is called a _safety lamp_.
This is a lamp enclosed in a wire cylinder, the interstices of which are
so extremely small as, whilst it gives light, will not explode the gas.

Another injurious exhalation in coal mines arises from the formation of
carbonic acid gas, or fixed air (26), and is called _choke damp_. It is
the property of inflammable air to rise to the upper parts; but this, on
account of its weight, occupies principally the lower parts of mines,
and occasions death by suffocation, though it is by no means so fatal as
the former. In some mines a prevention of injury arising from each of
these gases is attained, by ascertaining the particular crevices in the
coal from which they issue, confining them at those places within a
narrow space, and, if possible, conveying them out of the mines, through
long pipes, into the open air.

There is yet another danger attending coal mines which requires to be
provided against, and this is inundation. Many mines have been destroyed
by the flooding of water, which springs up within them. The modes by
which this was formerly extracted were extremely laborious, and, in
numerous instances, entirely inefficacious. By means, however, of the
fire or steam engines now in use, the quantity of water raised from
mines is perfectly astonishing. Four engines in one of the collieries at
Whitehaven discharge more than twenty hogsheads per minute, or upwards
of 30,000 hogsheads in every twenty─four hours.

The coal trade, which at present affords so important a nursery for our
seamen, and, in numerous other respects, yields advantages of the most
beneficial description to this country, was entirely unknown a few
centuries ago. Coals were not generally adopted as fuel until the
beginning of the reign of Charles I. They were, however, noticed in
documents anterior to the reign of Henry III., for, that monarch, in the
year 1234, renewed a charter, granted by his father, to the inhabitants
of Newcastle, by which they were permitted to dig coal upon payment of
100_l._ per annum. Coals had been introduced into London before 1306;
for in that year, the use of them as fuel was prohibited, from the
supposed tendency of their smoke to corrupt the air. About the beginning
of the sixteenth century, the best coals were sold in London at the rate
of 4_s._ 1_d._ per chaldron, and at Newcastle for no more than 2_s._
6_d._ During the ensuing century, however, they were received into such
general use, that, in 1648, on a scarcity of coal in London, many of the
poor are said to have died from want of fuel. The whole quantity of
coals imported into London has been estimated, on an average of four
years, ending in March, 1815, to amount to 1,170,000 chaldrons per
annum.

Some writers have imagined coal to be the remains of antediluvian
timber, which floated upon the waters of the deluge until several strata
of mineral substances had been formed: others conceive it to have been
antediluvian peat bog. It is called _pit coal_, from the circumstance
only of its being obtained from mines or pits; and, in London, for no
better reason than its having been conveyed thither by sea, it has the
name of _sea coal_.

Its uses as fuel are too extensively known to need here any
observations. By the distillation of coal an inflammable gas is
produced, which has of late been introduced for the lighting of
manufactories, and lighting several of the streets and shops of the
metropolis. This gas is conveyed by pipes, from the reservoir in which
it is collected, to great distances; and the light which it yields is
peculiarly brilliant and beautiful. It was at the foundery belonging to
Messrs. Boulton and Watts, at Birmingham, that the first public display
of _gas lights_ was made, in the year 1802, on the occasion of the
rejoicings for peace. In 1805 the cotton mills of Messrs. Phillips and
Lee, at Manchester, were lighted with gas, to the exclusion of lamps,
candles, and every other source of artificial light. In the beginning of
1816 it was estimated that, at the three gas─light stations, in
Peter─street, Westminster, Worship─street, and Norton Falgate, London,
twenty─five chaldrons of coals were used daily; and that these were
sufficient to supply with gas 125,000 large lamps. At the works in
Dorset─street, Fleet─street, the daily consumption of coal was about
three chaldrons, which afforded gas for 1,500 lamps.

The production of the _gas light_ is easily effected in miniature, by
putting common coal, pounded small, into the bowl of a tobacco─pipe, and
closely covering this with clay made into a stiff lute with water. When
the clay is dry, the bowl of the pipe must be put into the fire, and
there heated gradually. In a few minutes a stream of gas will issue from
the end of the pipe. This may be set on fire with a piece of paper, and
will burn with a bright flame. When the gas is no longer disengaged,
there will be found in the bowl of the pipe the remains of the coals, in
the form of coke.

It is estimated that one chaldron of good coals will afford from 17,000,
to 20,000 cubical feet of gas; and that one of the large burners in the
shops of London, consumes about four cubical feet per hour.

_Soot_ is produced from the smoke of burned coal, and is used as a
manure for cold, moist, and clayey meadows and pastures: and pounded
coal has been applied to the same purpose in some parts of the
Continent. By a process called charring, coal is divested of its humid,
acid, and bituminous particles, and is converted into a kind of cinder
called _coke_. This is employed in cases where intense heat is
requisite, as for the smelting of iron ore; and likewise where acid and
bituminous particles of coal would be detrimental, as in the drying of
malt.

What is usually termed _culm_ is the refuse or dusty coal, produced in
working the common coals. It contains much earthy matter, will not
kindle in an ordinary fire─place, but produces considerable heat and
flame in a furnace, where a strong current of air is introduced. In
England it is exempted from the high duty imposed on other coals, and is
sold at a very low price. It is used for burning lime, making salt, and
in steam engines.

219. _CANNEL COAL is of black colour, with little lustre, is not
laminar, but breaks in any direction, like pitch, and does not stain the
fingers._

This highly inflammable kind of coal is found abundantly in the
neighbourhood of Wigan, in Lancashire, where there is an entire stratum
of it about four feet in thickness. It is also found near Whitehaven, in
some of the pits at Newcastle, and in some parts of Scotland. Doubts
have been entertained respecting the name of this coal; but when it is
recollected that in Lancashire, whence it is chiefly brought, the word
candle is usually pronounced with the omission of the letter _d_, and
that, in many instances, the coal is used by the poor as a substitute
for candles, these will be immediately removed. In Scotland it has the
name of _parrot coal_.

No kind of coal takes fire so readily, nor burns with so cheerful and
brilliant a flame as this: and its not soiling the fingers, like pit
coal, renders the use of it peculiarly pleasant; but it does not cake,
and soon burns away. When first kindled, it crackles and splinters very
much; and, on this account, would be dangerous, were it not easily
prevented from so doing by being previously immersed for a little while
in water. Cannel coal has much the appearance of jet. It admits of being
turned in a lathe, and takes a good polish; and snuff─boxes and trinkets
made of it have in many instances been sold as jet (222). Of all the
kinds of coal that are used for gas─lights, none are said to be so
useful as this.

220. _STONE COAL, KILKENNY COAL, WELSH COAL, or GLANCE COAL, is of a
dark iron─black colour, with a metallic lustre and foliated texture; and
consists almost entirely of charcoal._

Unlike most other kinds of coal, this occurs both in stratified masses,
and in lumps, nested in clay. It is found in several countries of the
Continent, in Wales, Scotland, and near Kilkenny in Ireland.

When laid on burning coals, it becomes red hot, emits a blue lambent
flame in the same manner as charcoal; and is, at length, slowly
consumed, leaving behind a portion of red ashes. No smoke nor soot is
produced from this coal; but, on the contrary, it whitens the places
where the fume is condensed; and the effluvia which it gives out are
extremely suffocating.

This coal is chiefly used in the drying of malt.

221. _BOVEY COAL, BROWN COAL, or BITUMINOUS WOOD, is of brown colour,
and in shape exactly resembles the stems and branches of trees, but is
usually compressed. It is soft, somewhat flexible, and so light as
nearly to float when thrown into water._

The greatest abundance of this coal occurs at Bovey, near Exeter, from
which place it derives its name. The lowest stratum is worked at the
depth of seventy─five feet beneath the surface of the earth. It is also
found in Scotland, Ireland, and Germany.

As fuel, the Bovey coal is used only by the poorest classes of the
community, as, notwithstanding its burning with a clear flame, it emits
a sweetish but extremely disagreeable sulphureous gas, which is
injurious to the health of the inhabitants. It is principally used for
the burning of lime, and for the first baking of earthen ware.

222. _JET, or PITCH COAL, is a solid, black, and opaque mineral, harder
than coal, and found in detached_ _masses from an inch to seven or eight
feet in length, having a fine or regular structure, and a grain
resembling that of wood._

_It has sometimes been confounded with cannel coal (219), but it is
easily distinguished by its superior hardness: Jet cannot without
difficulty be scratched with a knife, whilst cannel coal may be marked
by the simple pressure of the nail._

The name of jet has been derived from Gages, a river of Lycia, whence
the ancients are said to have obtained this substance. It is frequently
cast ashore on the eastern coasts of England, together with pieces of
amber and curious pebbles, particularly near Lowestoft in Suffolk, and
in some parts of Yorkshire, where many persons employ their leisure in
searching for it, and forming it into various kinds of trinkets. Jet is
found in several countries of the Continent.

It is stated that in the district of Aude, in France, there are more
than 1,000 persons constantly employed in the fabrication of jet into
rosaries, buttons, ear─rings, necklaces, bracelets, snuff─boxes, and
trinkets of different kinds. Near fifty tons weight of it are annually
used for this purpose; and articles to the value of 18,000 livres are
said to be sold in Spain alone. In Prussia the amber diggers call it
_black amber_, because it is found accompanying that substance; and
because, like amber, it is faintly electric, or attracts feathers and
other light objects when rubbed. They manufacture it into various
ornamental articles, and sell these to ignorant persons, as black amber,
at a great price.

In different parts of the globe the trunks of trees, which have been
long buried, have passed into the state of jet; and, in almost all these
trees may be traced the distinctive characters of the species to which
they belong. They are more or less brittle, more or less unctuous,
according to the species, the degree of alteration, and the nature of
the soil. All of them have a smooth and glassy fracture, but all are not
adapted for the tool of the workman. When, for instance, the texture of
the tree presents only a mass of dry fibres, the jet obtained is dry and
brittle; and cannot be used in the forming of trinkets. But, if the
texture be unctuous the fibre acquires a considerable degree of
softness, is susceptible of being properly wrought, and receives a
perfect and beautiful polish.

A fictitious kind of jet is made of glass; and several varieties of
mineral pitch, and cannel coal, are imposed upon ignorant purchasers for
jet.

When jet is once set on fire it burns with a green flame, and continues
to burn for a considerable time, exhaling a strong bituminous smell. If
the heat be rendered greater, it melts.


                            GRAPHITE FAMILY.

223. _BLACK LEAD, or PLUMBAGO, is an inflammable mineral, which consists
of carbon, or charcoal (48), combined with iron, in the proportion of
about nine parts of the former to one of the latter._

_It is of dark iron─grey colour, with a strong metallic lustre, and so
soft that it is easily scratched with a knife. To the touch it is soft
and greasy; and, when handled, it stains the fingers. In weight it is
about twice as heavy as water._

The name of black lead has very improperly been given to this substance
from its appearance only, as it has no alliance whatever with lead. It
is usually found in kidney─shaped lumps of various size, and occurs in
several countries of Europe, but no where of such excellent quality as
in Borrowdale, Cumberland, where it has the name of _wadd_. The vein of
black lead lies between strata of slate, and is from eight to nine feet
thick. This mine is not opened more than once every three or four years,
the quantity thus obtained being found fully sufficient for the demand.
The only other mine of black lead in Britain is in Ayrshire, Scotland.

Artists in water─colours, if deprived of this mineral, would find great
difficulty in making their sketches; as the marks that are erroneously
made with it are more easily expunged than those of almost any other
substance. Hundreds of thousands of pencils are every year formed of
black lead. For this purpose the mineral is sawed into slender square
pieces. These are fixed into grooves, of the same shape, cut in cedar,
or some other soft wood; another piece of wood is then glued upon this,
and the whole is worked into a circular form. The finer kinds of black
lead are prepared for use by being boiled in oil before they are cut.
The coarser kinds, and the refuse of the sawings, are melted with
sulphur, and then cast into coarser pencils for carpenters. These may,
in general, be easily distinguished by their sulphureous smell. The
pencils that are manufactured in England are more esteemed on the
Continent than any others.

The powder produced in the sawing of pencils is employed for numerous
purposes. It is used for giving a bright gloss to cast─iron grates and
stoves, and defending them from rust, and from the action of fire. It
may also be advantageously applied to the inner surface of wooden
screws, to packing presses, the axles of various sorts of machines, to
slides, and other wood work, which are subject to friction. In this
respect it is far superior either to grease or soap. The makers of
razor─strops occasionally employ black lead in the composition which
they spread upon leather for the sharpening of razors; and, on the
Continent, it is sometimes used for blackening the hair. A coarser kind
of black lead is used for making the vessels that are used by chemists,
called crucibles.


                             RESIN FAMILY.

224. _AMBER is a substance usually of golden yellow colour,
semi─transparent, and of shining and somewhat resinous lustre. It is
occasionally seen of yellowish white colour, and nearly opaque._

The origin of amber is unknown. From the ants and other insects which it
frequently contains, there can be no doubt that it has once been in a
fluid state: and some writers have thought that it is a resinous juice,
gradually modified by the action of sulphuric acid (24); but this is
entirely conjecture. The ancients called it _electron_, and attributed
its formation to the sisters of Phaëton, who, lamenting the death of
their brother, were converted into poplar trees; these, it was said,
instead of tears, yielded every year this substance; which, issuing from
them in a fluid state, ran into the river, and there became hardened.

Amber is usually found in rounded and detached pieces, on the south
coast of the Baltic, on the eastern shores of England, and in small
quantity, on those of Sicily and the Adriatic; and a substance greatly
resembling it is occasionally found in gravel pits near London. The only
mines of amber at present known are in Prussia. These are worked in the
usual way, by shafts and galleries, to the depth of about 100 feet. The
amber is imbedded in a stratum of fossil wood, and occurs in rounded
pieces, from a few grains to three and even five pounds in weight. The
largest piece of amber ever known to be discovered in a detached state
was found near the surface of the ground, in Lithuania, about twelve
miles from the Baltic Sea. It weighed more than eighteen pounds, and was
deposited in the cabinet of the King of Prussia at Berlin. Very lately a
mass of amber, weighing thirteen pounds, was also found in Prussia. For
this piece 5000 dollars are said to have been offered; but the Armenian
merchants assert that it might have been sold in Constantinople for more
than 30,000 dollars.

Anterior to the discovery or general dispersion of precious stones from
India, amber was considered of great value as a jewel, and was employed
in all kinds of ornamental dresses. The ancient Romans were so partial
to this substance that Pliny, reprobating the great demand for it, says,
the Roman females would give larger sums for a puppet or figure in
amber, resembling a man or woman, however small its size, than they
would for the finest man or the most valiant soldier. Under the Emperor
Nero, persons were sent from Rome, for the purpose of collecting and
purchasing amber; and so much of it was at length obtained, that it was
used for ornamenting the nets and cordage employed in the theatres for
preventing the wild animals from approaching the populace there
assembled. It was likewise used to ornament the armour, the biers, and
funeral apparatus of such persons as were killed.

Amber is now chiefly in request by Greek and Armenian merchants, but it
is uncertain where they dispose of it. Some persons conjecture that it
is purchased by pilgrims previously to their journey to Mecca; and that,
on their arrival in that place, they burn it in honour of Mahomet.

The kind most in esteem is of a bright golden yellow colour. This is
occasionally manufactured into snuff─boxes, small vases, necklaces,
bracelets, cane─heads, and other ornamental articles, many of which are
purchased by the Turks, Russians, and Poles; but the general demand for
them has of late very much decreased. Some years ago the German artists
paid great attention to this substance; and many experiments were made
for the purpose of discovering means of removing its defects, and
improving its beauty. It is said that they possessed the art of
liquefying it to such a degree, that it could be run into moulds without
injuring its beauty; and that specimens of this liquefied amber are
preserved in the Electoral Cabinet at Dresden. There are still
considerable manufactories of amber at Stolpen, Konigsberg, Dantzic, and
Lubeck.

Amber, when wrought into ornaments, is first split on a leaden plate,
and then turned on a particular kind of whetstone. The polishing of it
is performed with chalk and water, or chalk and oil; and the work is
finished by rubbing the whole with clean flannel. Without great
attention it becomes very hot, and either flies into pieces, or takes
fire during the operation.

After having been roasted or melted, amber is readily soluble in oil,
and, in this state, constitutes the basis of several kinds of varnish.
It was formerly much used in medicine, but, in this respect, it is now
almost wholly neglected. Some persons, however, have still an absurd
notion that a collar or necklace of amber, tied round an infant’s neck,
will enable it to cut its teeth in safety. Oil of amber combined with
liquid ammonia constitutes a white soapy liquor called _eau─de─luce_.

It has already been mentioned that insects are occasionally found in
amber. These are generally in a very perfect state, and consist of
flies, small moths, &c. Grains of sand, pieces of iron pyrites, and the
leaves of plants, are also sometimes found in it. Insects, sand, and
other substances, are likewise remarked in a species of gum, called _gum
animè_, which, in colour, appearance, and qualities, so nearly resembles
amber, that it is almost impossible to distinguish the two substances
from each other. Large productions, which were formerly supposed to have
been made of amber, such as a column ten feet high in the Florentine
Museum, are now usually considered to have been formed of this gum; and
many of the large beads of what are sold as amber necklaces are made of
it.

If a piece of amber be fixed on the point of a knife and lighted, it
will burn entirely away, emitting at the same time a white smoke, and a
somewhat agreeable though sickly odour. When rubbed it has the property
of attracting light bodies; hence one of the ancient Greek philosophers
attributed to it a certain kind of life. From the name of _electron_,
which was given to it by them, in consequence of this property, we
derive our word electricity.


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                     CLASS IV.–METALLIC SUBSTANCES.

                                ───────

                         OF METALS IN GENERAL.


225. METALS, in a perfect state, are easily distinguished from other
minerals, by a peculiar brilliancy which pervades their whole substance,
and which has the name of _metallic lustre_; by their complete opacity,
and their great weight in proportion to that of other mineral
substances.

When taken from the earth they are found in one or other of the four
following states: 1. In a native or metallic state, 2. Combined with
sulphur, 3. In a state of oxide (21) 4. Combined with acid.

Metals, when found in a state of combination with other substances, have
the name of _ores_. They are in general deposited in veins (4), of
various thickness, and at various depths in the earth. The mode of
obtaining them is to penetrate from the surface of the earth to the
vein, and there to follow it, in whatever direction it may lie. The
hollow places thus formed are called _mines_, and the men employed in
them are denominated _miners_. When the veins are at a great depth, or
extend to any considerable distance beneath the surface of the earth, it
is necessary, at intervals, to make openings, or _shafts_, to the
surface, for the admission and circulation of the air; and also to draw
off the water which collects at the bottom, by drains, pumps, or
steam─engines, as the situation or circumstances require.

After the metallic ores are drawn from the mine, they, in general, go
through several processes before they are in a state fit for use. Some
of them are first washed in running water, to clear them from earthy
particles. They are then piled with combustible substances, and burnt or
roasted, for the purpose of ridding them of the sulphur or arsenic with
which they may happen to be combined, and which rises from them in a
state of fume or smoke. Thus, having been freed from impurities, they
undergo the operation of melting, in furnaces constructed according to
the nature of the respective metals, or the uses to which they are to be
subsequently applied.

The knowledge of metals is a subject of great importance to mankind.
Their use in trade is so frequent, and in the arts so various and so
interesting, that few objects can be more worthy of attention than
these.


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                       ORDER I.—MALLEABLE METALS;


OR, SUCH AS ARE CAPABLE OF BEING FLATTENED OR ELONGATED BY THE HAMMER,
WITHOUT TEARING OR BREAKING.

                                ───────

226. _PLATINA, the most ponderous of all the metals with which we are
acquainted, is, when purified, about twenty times heavier than water. It
is also one of the hardest and most difficult to be melted, is of white
colour, but darker and not so bright as silver, and is found only in
small blunted and angular grains or scales in the sands of some of the
rivers in South America._

If platina could be obtained in sufficient quantity, it would perhaps be
the most valuable of all metals. The important uses to which it is
applicable may easily be imagined when we state that it is nearly as
hard as iron, and that the most intense fire and most powerful acids
have scarcely any effect upon it. Platina is not fusible by the heat of
a forge, but requires either the concentrated rays of the sun in a
burning mirror, the galvanic electricity, or a flame produced by the
agency of oxygen gas.

It is admirably adapted for the uses of the philosophical chemist:
although vessels made of it must always be found expensive, from its
being necessary to solder them with gold; and although it has the
disadvantage of being subject to corrosion by the application or use of
caustic alkalies. Vessels made of it are not liable to be broken, and
are as indestructible as those made of gold. When properly refined, its
colour is somewhat betwixt that of silver and iron. Not being liable to
tarnish like silver, platina is manufactured into several kinds of
trinkets.

Its ductility is so great that it may be rolled into plates, or drawn
into wire; and platina wire, for strength and tenacity, is considered
much preferable to that either of gold or silver of equal thickness.
Platina is also made into mirrors for reflecting telescopes, into
mathematical instruments, pendulums, and clock─work; particularly where
it is requisite that the construction of these should be more than
usually correct, as platina is not only free from liability to rust, but
is likewise subject to very little dilatation by heat. It is sometimes
beaten into leaves and applied to porcelain, in the same manner as leaf
gold; and its oxide (21) is used in enamel painting, and might be used,
with great advantage, in the painting and ornamenting of porcelain. The
platina employed for all these purposes is repeatedly melted with
arsenic, as without the aid of this it could only be obtained in very
small masses, owing to the intense heat that is required for its fusion.

This extraordinary metal was unknown in Europe until about the year
1735, when it was first brought from South America by Don Antonio Ulloa.

227. _GOLD is a metal distinguished by its yellow colour; by its being
next in weight to platina, softer than silver, but considerably more
hard than tin; and being more easily melted than copper._

_It is found in various states, massive, in grains, small_ _scales, and
capillary, or in small branches. It cannot be dissolved in any acid
except that called aqua regia (207), and is more than nineteen times
heavier than water._

The countries of hot climates are those chiefly in which gold is
discovered. It abounds in the sands of many African rivers, and is very
common in several districts both of South America and India. The gold
mines of Lima and Peru have had great celebrity; but, since the late
commotions in the Spanish colonies, the working of them has been much
neglected. It is from Brazil that the greatest part of the gold which is
seen in commerce is brought. The annual produce of the various gold
mines in America has been estimated at nearly 9,500,000_l._ sterling.

The principal gold mines in Europe are those of Hungary, and next to
them those of Saltzburg. Spain is probably very rich in gold.
Considerable mines were worked there in former times, particularly in
the province of Asturia; but, after the discovery of America, these were
given up or lost. Gold has been found in Sweden and Norway, and also in
several parts of Ireland, but particularly in the county of
Wicklow.—Among the sands of a mountain stream in that county, and among
the sand of the valley on each side, lumps of gold are occasionally
found. Pieces have been discovered which weighed twenty─two ounces, but
they are generally much smaller, from two or three ounces to a few
grains. It is said that lumps of gold, of large size, have been used as
weights in some of the common shops, and that others have been placed to
keep open the doors of cottages and houses in some parts of Ireland, the
owners not knowing what they were. Gold is also occasionally found in
Cornwall, and some other counties of England. Wherever it occurs it is
commonly observed in a state of alloy with copper or silver, and in the
form of grains, plates, or small crystals.

Gold was formerly obtained in Scotland. It is asserted that, at the
marriage of James V. there were covered dishes filled with coins made of
Scottish gold, and that a portion of these was presented to each of the
guests by way of dessert. Very extensive operations for the discovery of
gold were carried on during the reign of Queen Elizabeth, at Leadhills,
in Lanarkshire, under the direction of an Englishman whose name was
Bulmer. The trenches, the heaps of soil that were turned up, and other
marks of these operations, are yet visible near the road between
Leadhills and Elvanfoot. It is said that 300 men were then employed; and
that, in the course of a few years, a quantity of gold was collected,
equal in value to 100,000_l._ sterling. Not many years ago similar
operations were commenced under the superintendence of a celebrated
manager of the Scottish lead mines. The gold was found immediately under
the vegetable soil; and the method of obtaining it was to direct a small
stream of water, so as to carry the soil along with it, to basins or
hollow places, where the water might deposit the matters carried down by
the force of its current. The matter thus deposited was repeatedly
washed, till the whole of the earthy substances were carried off. The
gold, being heaviest, sunk to the bottom, and remained behind. The soil
still furnishes gold; but the produce would by no means be equal to the
expense of collecting it. Searching for gold, therefore, is now regarded
only as an amusement, and not as a source of profit. Grains of this
metal are sometimes found, after great floods, among the sand of brooks
in different parts of Scotland.

The mode of extracting gold from its ore is by reducing it into a fine
powder, and mixing this powder with quicksilver (228). The latter having
the quality of uniting with itself every particle of the precious metal,
but being incapable of union with the other substances, extracts it even
from the largest portions of earth. The quicksilver, which has absorbed
the gold, is then separated by means of heat; it flies off in vapour,
and leaves the other metal in the vessel used for the operation.

Gold has been known, and in request, from the very earliest ages of the
world. By the assent of civilized nations, it has become the
representative of wealth under the form of money; and it is now an
universal circulating medium for the purchase of all kinds of
commodities. It has been chosen to occupy this important place on
account of its scarcity, its weight, and other valuable properties.

As gold is not liable to tarnish or rust, it is frequently employed for
ornaments of dress. But, beyond its use in the coinage, its most
important uses are for goldsmith’s work, in jewellery, and for gilding.
In each of these its standard or purity is different. That denominated
_coinage_, or _sterling gold_, consists of an alloy of about twenty─two
parts of gold with two parts of copper; whilst gold of the _new
standard_, of which gold plate, watch─cases, and many other articles are
made, consists of only eighteen parts of gold, and six parts of copper.
Each of these is stamped at Goldsmiths’ Hall; the former with a lion, a
leopard’s head (the mark of the goldsmith’s company), a letter denoting
the year, the king’s head, and the manufacturer’s initials; the latter
is stamped with the king’s head, letter for the year, a crown, the
number 18 to designate its quality, and the manufacturers initials. The
coinage gold of Portugal and America is of the same standard as our own;
that of France is somewhat inferior; and Spanish gold is inferior to the
French. The Dutch ducats and some of the Moorish coins are of gold
unalloyed. _Trinket gold_, which is unstamped, is in general much less
pure than any of the above; and the _pale gold_ which is used by
jewellers is an alloy of gold with silver.

The ductility and tenacity of this metal, particularly when alloyed with
copper, are extremely remarkable, and are fully proved by the great
extent to which a very small quantity of it may be beaten into leaves,
or drawn into wire. Leaves of gold may be beaten so thin, that a single
grain may be made into fifty─six leaves, each an inch square. These
leaves are only 1/282000 of an inch thick; and the gold leaf which is
used to cover silver wire is but the twelfth part of that thickness. An
ounce of gold upon silver wire is capable of being extended more than
1,300 miles in length: and sixteen ounces of gold, which, in the form of
a cube, would not measure more than an inch and a quarter on each side,
will completely gild a silver wire in length sufficient to compass the
whole earth like a hoop.

Gold is beaten into leaves upon a smooth block of marble, fitted into
the middle of a wooden frame about two feet square, in such manner that
the surfaces of the marble and of the frame are exactly level. On three
of the sides there is a high ledge; and the front, which is open, has a
flap of leather attached to it, which the man who beats the gold uses as
an apron for preserving the fragments that fall off. In this process
there are three kinds of animal membranes used, some of which are laid
between the leaves to prevent their uniting together, and others over
them to defend them from being injured by the hammer. The exterior cover
is of parchment. For interlaying with the gold, the smoothest and
closest vellum that can be procured is first used; and, when the gold
becomes thinner, this is exchanged for much finer skin, made of the
entrails of oxen, prepared for this express purpose, and hence called
_gold beater’s skin_. After the leaf has been beaten to a sufficient
degree of thinness, it is taken up by a cane instrument, and thrown flat
upon a leathern cushion, where it is cut to a proper size with a square
frame of cane, or wood edged with cane. These pieces are then fitted
into books of twenty─five leaves each, the paper of which has been well
smoothed, and rubbed with red bole (127), to prevent them from sticking.
The leaves are about three inches square, and the gold of each book
weighs somewhat more than four grains and a half.

It was anciently the custom to beat gold into thin plates, and to gild
the walls of apartments, the surfaces of dishes, drinking utensils, and
other articles, by covering them with such. But this was not only an
expensive, but it must have been a most clumsy mode of ornament. The
present modes of gilding are very different. When wood is to be gilded,
the surface is first smeared with an adhesive kind of oil, or with a
kind of glue called size; and the gold leaf, above mentioned, is then
spread upon it by a tuft of cotton or other soft substance.

The _gilding of iron or copper_ is performed by cleaning and polishing
its surface, and then heating it till it has a blue colour. When this
has been done, a layer of gold leaf is put on, slightly burnished down,
and exposed to a gentle fire. It is usual, in common work, to place
three such layers, or four at the most, each consisting of a single
leaf. The heating is repeated at each layer, and last of all the work is
burnished. For gilding in _or moulu_, as it is denominated by the
French, an amalgam consisting of ten parts of mercury and one part of
gold is used. This is spread upon the metal, and is afterwards exposed
to the action of a fire sufficiently strong to evaporate the mercury and
leave the gold behind. The gilding in _or moulu_ is much more solid and
permanent than that by the former method.

When gilding is pale and dirty, it may be revived by means of what is
called _gilding wax_, a composition of yellow wax, bole (127), verdigris
(230), and alum.

A very beautiful gilding upon metals, and particularly upon silver, is
effected by soaking clean linen rags in a solution of gold made by aqua
regia (207). The rags are dried and burnt; and the ashes are carefully
preserved. These ashes are used by taking a sound cork, moistening it
with a little water, dipping it into the ashes, and then rubbing
strongly a portion of them on the surface of the silver, which should be
perfectly clean and bright. By this simple and economical process, it
will be covered with an extremely thin coating of gold, the colour and
brilliancy of which may be heightened by burnishing. The ornaments upon
snuff─boxes, fans, and various kinds of trinkets, are merely thin plates
of silver, gilded in this manner.

The _edges of tea─cups_, and other similar articles, may be gilded,
though not in a very durable manner, by applying a thin coat of amber
varnish (224), and then placing leaf─gold upon it. When the varnish is
dry, the gold is to be burnished.

Gold, in a state of solution, is sometimes used for staining marble,
ivory, ornamental feathers, and other articles, a purple─red colour,
which cannot be effaced. By chemical processes an oxide (21) is obtained
from this metal, which is employed for giving those beautiful shades of
lilac, rose colour, red and purple, which we observe in glass and
porcelain.

A _gold powder for painting_ may be made by uniting one part of gold
with eight parts of mercury (228), and afterwards evaporating the latter
by heat.

The article denominated _gold wire_ is generally silver wire gilded,
very little wire being made entirely of gold. Its uses are chiefly for
embroidery and filagree work. _Gold thread_ consists of flatted silver
gilt wire, laid over a thread of yellow silk, by twisting it in a
machine with iron bobbins. It is of this, and not of gold, that the
article called _gold lace_ is made. The Chinese, instead of flatted
wire, use slips of gilt paper, which they interweave in their stuffs,
and twist upon silk threads.

228. _MERCURY, in its native state, is called quicksilver, and is found
in small globules of shining, silvery appearance, scattered through
different kinds of stones, clay, and ores. It is nearly fourteen times
heavier than water._

_The principal ore of mercury, and that from which the metal is chiefly
obtained, is_ cinnabar. _This is of red colour, and consists of mercury
mineralized with sulphur. It is sometimes found in a massive state,
sometimes in grains, and sometimes crystallized; and chiefly among rocks
of the coal formation._

The most productive mines of cinnabar are in the palatinate of Germany,
at Idria in Carniola, and at Almaden in Spain. Those of Idria are
supposed to be more valuable than any of the others. Their first
discovery, which was somewhat more than three hundred years ago, was
made in a very extraordinary manner. This part of the country was then
much inhabited by coopers; and one of the men, on retiring from work in
the evening, placed a new tub under a dropping spring, to try if it
would hold water; and, when he came in the morning, he found it so heavy
that he could scarcely move it. Examining into the cause of this
extraordinary circumstance, the man observed that it was owing to a
shining and ponderous fluid which was at the bottom. The affair was
noised abroad, and a society of persons was formed to search further,
and discover the mine from which this quicksilver had flowed. Such was
their success that the reigning Duke of Austria paid them a compensation
for the discovery, and took the mine into his own possession. The
greatest perpendicular depth of this mine is now more than 830 feet. It
is descended by buckets, or by ladders placed obliquely in a zigzag
direction. In some parts of the mine the pure metal flows in small
streams, so that in six hours a man has been known to collect more than
thirty─six pounds weight of it. In other parts it is found in a
multitude of little drops, either in ores or in clay. The whole produce
of the mine is said to exceed a hundred tons weight of mercury per
annum.

It has been asserted that, several years ago, in digging out clay for
the foundation of a house opposite to the King’s Arms inn, in the street
called Hyde─hill, in Berwick─upon─Tweed, a quantity of native mercury
was discovered. The clay, when dug out, lay for some time in the place
to which it was conveyed; and the mercury was observed to exude from the
small fissures or cracks that were formed as it dried. It is said that,
several years afterwards, in making some alteration in the yard of the
same house, the workmen penetrated into the same bed of clay; and that
it then appeared to be impregnated with native mercury, which ran out in
small globules.

Mercury is sometimes imported into Europe from Peru, and from the East
Indies.

The mode of extracting it from _cinnabar_ is said to be by mixing this
ore either with pounded chalk, or with half its weight of iron filings,
and distilling it in a stoneware retort. By this process the sulphur
combines with the iron, and the mercury, in a state of purity, passes
into the receiver.

When pure or native mercury occurs in mixture with other substances,
these are stamped or ground into a coarse powder. Water is poured upon
them; they are briskly stirred until the water becomes thick and turbid,
and then are left to settle. This operation is repeated till the water
runs off perfectly clear. The substance at the bottom, which is
principally mercury, is then put into large iron retorts and the metal
is obtained, free from all extraneous matters, by distillation.

It is the singular property of this metal, which has no other alliance
whatever with silver than its appearance, to be capable of division, by
the least effort, into an indefinite number of particles, each of which
assumes a spherical form; and to be always in a fluid state in the
common temperature of our atmosphere. Even during the most intense
frost, it still retains its fluidity. By the effect, however, of extreme
cold artificially produced, mercury becomes a solid metal, and in this
state may be beaten with a hammer and extended without breaking; but
care must be taken that it does not touch the fingers, as it would
blister them and cause unpleasant sores, in the same manner as any
burning substance.

Mercury has been known from the remotest ages; and it was employed by
the ancients in gilding, and in the operations of separating gold and
silver from their ores, in the same manner as at present. Being the
heaviest of all fluids of which we have any knowledge, and not
congealing in the temperature of our climate, it has been preferred,
before all others, for barometers, as a measure of the weight of the
atmosphere. And, as heat dilates mercury similarly to other fluids, it
is likewise made into thermometers. Mercury is sometimes used in
medicine in its pure metallic state.

The combinations of mercury with other metals are termed _amalgams_.
That of mercury and gold is formed so readily, that if gold be dipped
into mercury, its surface immediately becomes as white as silver. An
amalgam of mercury and gold is employed for the gilding, and of mercury
and silver for the silvering of metals.

Mercury and tin combined together form the substance that is used for
the _silvering of looking─glasses_. The process is as follows: A
quantity of tin─foil, equal in size to the glass, is evenly placed on a
flat stone or table; and mercury, in which some tin has been dissolved,
is poured upon it, and spread with a feather, or bunch of cloth, until
its union has covered every part. A plate of glass is then cautiously
slided upon it, from one end to the other, in such manner that part of
the redundant mercury is driven off, or swept away before its edge. The
remainder is now united to the tin. The glass is then loaded with
weights all over, so as to press out still more of the mercury. By
inclining the table, this remaining mercury becomes discharged; and, in
a few hours, the rest of the tin─foil and mercury adhere so firmly to
the glass, that the weight may be removed without any danger of its
falling. About two ounces of mercury are requisite for covering, in this
manner, three square feet of glass.

By means of mercury a _fulminating powder_ is made, which, when struck
with a hammer on an anvil or flat iron, such as is used by laundresses,
explodes with a stunning and disagreeable report, and with such force as
to indent both the anvil and the hammer. Four or five grains are as much
of this powder as ought to be used for such experiments. Its force is
much greater than that of gunpowder, but does not extend so far. Hence
it is a substance which might be rendered of great use in the blasting
of rocks.

_Corrosive sublimate_ is an extremely poisonous preparation from
mercury. Among other uses, it is employed by dyers as a mordant to fix
their colours. From certain proportions of corrosive sublimate rubbed
together, until they are perfectly incorporated, is formed _calomel_; a
salt which, of late years, has been extensively and most usefully
employed in medicine.

A valuable red colour or pigment called _vermilion_, or _artificial
cinnabar_, which was as well known to the ancients as it is to the
moderns, is usually formed of three parts of mercury and one of sulphur,
melted together, heated to redness, and then sublimated out of contact
of the air. The manufacture of vermilion was long kept a secret by the
Dutch; and it is stated that, before the late war, nearly 50,000 pounds
weight of it were annually made, in three furnaces, by four workmen,
near Amsterdam. Native cinnabar is sometimes used for the same purpose;
but the artificial kind is preferred on account of the purity and
brightness of its colour.

229. _SILVER is a white, brilliant, sonorous, and ductile metal,
somewhat more than ten times heavier than water._

_It is found in different states. Of these the principal is denominated_
native silver, _from its being nearly in a state of purity. Native
silver sometimes occurs in small lumps, sometimes in a crystallized
form, and sometimes in leaves, threads, or wire. In many instances the
latter are so connected with each other as to resemble the branches of
trees, in which case the ore is called_ dendritic. _There are also
several_ ores of silver, _in which this metal is combined with lead,
antimony, arsenic, sulphur, and other substances._

The silver that is produced from the mines of Potosi, in South America,
is of the dendritic kind; and is considered by the Spaniards as the
purest that is known. A range of mountains near Potosi, about twenty
miles in circumference, is said to be perforated by more than 300
shafts, or openings of mines, and to produce, in the whole, from 30,000
to 40,000 dollars’ worth of ore per week. The annual produce of the
silver mines in America has been estimated at near 2,400,000_l._
sterling.

Silver is also found in several parts of Europe; and, some years ago,
there were mines of this metal, worked to a great extent, at Konigsberg
in Norway. These were discovered in 1623, and they were found so
profitable, that in 1751 forty─one shafts and twelve veins were wrought
there; and 3,500 officers, artificers, and labourers, were employed. The
perpendicular depth of the principal shaft was more than 750 feet.
Specimens of native silver are not uncommon from some of the
copper─mines of Cornwall; and, many years ago, a vein of silver ore was,
for a short time, wrought with considerable advantage in the parish of
Alva, Stirlingshire, Scotland. It is said that from 40,000_l._ to
50,000_l._ worth of silver was obtained from it before the repository
was exhausted. We are informed that a mass of capillary native silver
was found, in veins traversing the blue─coloured limestone of Isla, one
of the Western Islands of Scotland. Great quantities of silver are
extracted from lead. There was lately melted in one refining house in
London 50,000_l._ worth of this metal, from lead of the Beralston mines
in Devonshire.

Different methods are employed, in different countries, to extract
silver from its ore. In Mexico and Peru the mineral is pounded, roasted,
washed, and then mixed with mercury in vessels filled with water; a mill
being employed for the more perfectly agitating and mingling them. By
this process the silver combines with the mercury. The alloy thus
obtained, after undergoing some further processes, is submitted to the
action of heat, by which the mercury passes off in a state of vapour,
leaving the silver behind. The silver is then melted and cast into bars
or ingots. In other countries, after the earthy matters are cleared from
the silver ore by pounding and washing, the remainder is melted with
lead: which, by a subsequent process, is separated, and leaves the
silver alone and pure.

This metal ranks next in value to gold. Like gold, it is coined into
money, and is manufactured into various kinds of utensils, such as
goblets, vases, spoons, and dishes, which have the general appellation
of _silver plate_. For all these purposes it is alloyed with copper,
which does not affect its whiteness, and is not easily detected, unless
it be in too great proportion: the intention of this is to render it
harder than it would otherwise be, and thereby the better to adapt it to
receive fine and sharp impressions on being cast. Our _standard silver_
is composed of somewhat more than 12¼ parts of pure metal and one part
of copper; and the metal of this standard is used, both for silver
plate, and in the coinage. The mark or stamp which is given to it at
Goldsmiths’ Hall is similar to that which has been explained for
sterling gold.

After platina (226) and gold (227), silver is considered the most
unchangeable of all metals. The air does not easily act upon its surface
in such manner as to injure it; but, when long exposed to the
atmosphere, especially in frequented or smoky places, it acquires a
covering or rust of dark brown colour, which, on examination, is found
to be what chemists denominate _sulphuret of silver_. The fumes of
sulphur and other inflammable substances blacken silver. Various powders
have been contrived with a view to restore to plate its original lustre;
but these should be used with caution, as some of them are very
injurious.

Silver is nearly as ductile as gold. It may be beaten into leaves so
thin that a single grain in weight will cover a space of more than
fifty─one inches; and it may be drawn into wire much finer than a human
hair, indeed so fine that a single grain of silver has, in this form,
been extended nearly to the length of 400 feet. It is this wire gilded
that has the name of gold wire; and what is denominated _gold lace_
(227) is but flatted silver thread gilt, twisted round silk, and woven.

The _plating_ of copper with silver is a very useful operation, and is
thus performed. Plates of silver are bound with iron wire, upon small
ingots of copper. The quantity generally allowed is one ounce of silver
to twelve ounces of copper. The surface of the plate of silver is made
not quite so large as that of the copper; and upon the edges of the
copper, which are not covered by the silver, a little borax (204) is
put. By exposing the whole to a strong heat, the borax melts; and, in
melting, contributes to fuse that part of the silver to which it is
contiguous, and to attach it, in that state, to the copper. The ingot,
with its silver plate, is then rolled between steel rollers moved by
machinery, till it is of proper thickness. It is afterwards cut into
such sizes and to such shapes as may be required for use. An ounce of
silver is thus often rolled out into a surface of three square feet,
having its thickness, upon the copper, not more than the
three─thousandth part of an inch. Hence we ought not to be surprised at
the silver being soon worn from the sharp edges of plated goods. To
prevent this, it is customary, with the best articles, to have all the
edges, and the parts liable to be worn, formed, to a considerable
thickness, of silver.

What is called _French plate_ is made by heating copper, or more
frequently, brass, to a certain degree, then applying leaf─silver to the
surface, and strongly rubbing it with a burnisher. The durability of
this plating depends of course on the number of leaves which are applied
on a given surface. For ornaments that are not much used ten leaves may
be sufficient; but a hundred will not last long, if the metal be exposed
to frequent handling or washing.

Besides the above, there are various modes of _silvering_ metal
articles, or, as it is called, _washing_ them with silver. All these are
performed by different chemical preparations of this metal.

The article denominated _shell─silver_, used by painters, is prepared,
by carefully grinding silver─leaf, with a little honey or gum water upon
a slab, or in a mortar, and separating the honey or gum by means of
water. When this is washed away, the silver may be put on paper, or kept
in shells, for use. When it is to be used, it must again be diluted with
gum water.

The application of silver─leaf for the silvering of paper or wood is
similar to that of gold─leaf (227).

Silver, dissolved in aqua fortis (nitric acid, 30), yields crystals,
which, afterwards melted in crucibles, form that grey mass usually
called _lunar caustic_, and by chemists _nitrat of silver_. This
preparation is of considerable use in surgical cases, being employed to
keep down fungous or proud flesh, in wounds and ulcers, and also for the
consuming of warts, small wens, and other excrescences upon the skin. It
is likewise, though a most violent medicine, sometimes given internally,
but in very small doses, to persons subject to epileptic fits. The
liquid in which the silver is dissolved becomes excessively caustic. It
gives to the skin, the hair, and almost all animal substances, an
indelible black colour. Hence it is often used as a specific for dyeing
the human hair. No person, however, would employ it for this purpose,
who was acquainted with its injurious qualities, not only to the hair
itself, but also to the skin, if permitted to come in contact with it.

The article called _indelible_, or _permanent marking ink_, for marking
linen, and other wearing apparel, is formed by dissolving, in a glass
mortar, two drachms of nitrat of silver, in six drachms of pure water,
and then adding to them two drachms, by measure, of thick gum water.
This is the ink for writing on the linen.—In another vessel dissolve
half an ounce of salt of tartar, or of the subcarbonat of soda, of
commerce, in four ounces of water; and add to the solution half an
ounce, by measure, of thick gum water. This forms the preparatory
liquor. With this the linen is to be thoroughly wetted at the part
intended to be marked. The linen is to be dried, and then to be written
upon by a clean pen dipped in the marking ink. The letters will at first
be pale, but by exposure to light and heat, they will soon become black;
and be so permanently fixed, that no washing nor bleaching can efface
them.

The attention of the curious has of late been turned to a very
extraordinary compound called _fulminating silver_, which explodes
without heat, and with even the slightest degree of friction. Of this
compound little _fulminating balls_ have been made. These are globules
of thin glass, each somewhat larger than a pea, and containing a grain
or two of fulminating silver. After the silver is put in, it is secured
by a piece of soft paper, pasted over the ball, so as completely to
cover it. These balls explode by merely crushing them under the heel of
the shoe. What are called _fulminating bombs_ are similar balls, but of
the size of hazel nuts. No one should attempt to explode these by
crushing them with the shoe, as their explosive effect is so violent as
sometimes to prove injurious.

Fulminating silver requires the utmost care. It should never be put into
phials, nor should it be in any way handled so as to produce much
friction. It is the most dangerous preparation that is known. The mere
touch of a hard substance will sometimes explode it; and its very
preparation is so hazardous that this ought never to be attempted
without a mask upon the face with strong glass eyes.

The following are three pleasing experiments with preparations of
silver:

1. Mix or amalgamate together four parts of silver leaf with two parts
of mercury (228) and dissolve this in diluted aqua fortis. To the
solution add as much water as will be equal to thirty times the weight
of the metals employed. Pour a portion of the above mixture into a
phial, and place at the bottom a small piece of silver. After it has
stood awhile, little filaments of silver will be seen to shoot up from
it somewhat in the form of a shrub. This apparent vegetation is
popularly called the _tree of Diana_.

2. A production nearly similar may be obtained by adding a little
quicksilver to a solution of nitrat of silver in water.

3. Drop upon a clean plate of copper a small quantity of solution of
lunar caustic, or nitrat of silver. In a short time a metallic
vegetation will be perceptible, branching out in pleasing forms, and in
various directions.

230. _COPPER is a red or orange─coloured metal, about nine times heavier
than water. It is the most sonorous of all metals, and, except iron, the
most elastic._

_It is found under a great variety of forms, sometimes in masses of pure
metal, but, more frequently, in combination with other substances,
particularly sulphur._

There are valuable copper mines in every quarter of the world; and the
use of copper is probably of greater antiquity than that of any other
metal. It is mentioned in the Old Testament; and, at a very early
period, domestic utensils and instruments of war were made of bronze, or
a compound of copper and tin. Even during the Trojan war, as we learn
from Homer, the combatants had no other armour than what was made of
bronze. The Greek and Roman sculptors are said to have executed fine
works of art in porphyry, granite, and other hard minerals, by means of
copper instruments; whence historians have been induced to believe that
the ancients possessed the secret of rendering this metal as hard as
steel: some of them even imagined that they had the means of converting
it into steel.

Copper is very abundant in several parts of Great Britain, particularly
in the island of Anglesea. The copper mines of Anglesea are situated on
the top of a mountain, and form an enormous cavity more than five
hundred yards long, a hundred yards broad, and a hundred yards deep. The
ore is got from the mine by pickaxes, and blasting with gunpowder. It is
then broken with hammers into small pieces, an operation which is
chiefly performed by women and children. After this, it is piled into
kilns of great length, and each about six feet high; from the upper
parts of which flues are attached that communicate with what are called
sulphur chambers. The kilns are closely covered; and fires are lighted
in different parts, that the ore may undergo the process of roasting.
The whole mass gradually kindles, and the sulphur, which is combined
with the ore, is expelled in fumes, by the heat, and is conveyed,
through the flues, to the sulphur chamber. This process occupies from
three to ten months, according to the size of the kilns; and, during
that period, the sulphur chamber is cleared four or five times. When the
operation is complete, or the ore is freed from the sulphur, it is taken
to places denominated slacking pits. It is subsequently conveyed to the
smelting houses, where, by intense heat, the pure metal is drawn off in
a fluid state.

As the water, which passes through several parts of the Paris mine, is
strongly impregnated with sulphat of copper (209), or copper held in
solution by sulphuric acid (24), the proprietors turn the course of this
water through certain large and shallow pits, which they have formed for
the purpose, and in each of which they place a quantity of iron. A
decomposition here takes place: the iron is corroded, and, at length,
entirely dissolved, and the copper, in the form of a brown mud, falls to
the bottom. One ton weight of iron, thus immersed, will produce nearly
two tons of copper mud, each of which, when melted, will yield sixteen
hundred weight of metal. This mode of obtaining copper is said to have
been an accidental discovery from one of the workmen, several years ago,
having left a shovel in the water, which, when afterwards taken out,
appeared changed into copper.

The magnitude of the above mentioned copper works may readily be
conceived, when it is stated that the beds of ore are, in some places,
more than sixty feet in depth: that the proprietors employ more than
1000 workmen; and that they ship, from the adjacent port of Amlwch,
upwards of 20,000 tons of copper, annually.

There is at Ecton, in Staffordshire, a copper mine which is now worked
at the depth of 1416 feet below the surface of the ground. This is the
deepest mine in England.

The uses of copper are numerous and important. When rolled into sheets,
betwixt large iron cylinders, it is employed for the covering of houses,
sheathing the bottoms of ships, and other purposes. As a covering for
houses, copper is lighter than slate, but whether it be more durable has
not been yet ascertained. The coppering of ships tends to facilitate
their progress through the water, by presenting a smoother surface than
that of wood, and not permitting shell animals to fasten to it as they
do to wood. It likewise preserves the bottoms of the ships from being
punctured by marine worms; and consequently secures to them a longer
duration than they would otherwise have. Plates, or flat pieces of
copper, are used by artists for engraving pictures upon, either by
cutting them with a sharp steel instrument, or corroding them with aqua
fortis (206), in lines drawn by a needle through a thin coat of wax
spread upon their surface.

Copper is manufactured into various kinds of cooking utensils. Great
care, however, ought to be taken that acid liquors, or even water
intended for drinking, or to be mixed with food, be not suffered to
stand long in such vessels, otherwise they will dissolve so much of the
metal as to give them disagreeable and even poisonous qualities. Yet, it
is remarkable that, while acid liquors are kept boiling, they do not
seem to dissolve any of the metal. Hence it is that confectioners, by
skilful management, prepare the most acid syrups in copper vessels,
without their receiving any unpleasant taste or injurious quality from
the metal. All vessels formed of this metal which are employed in
cookery, ought to have their inner surface covered with a coat of tin
(238).

As copper does not, like iron, strike fire by collision, it has on this,
as well as on some other accounts, been substituted for iron in the
machinery which is employed in gunpowder mills. It is also made into
water pipes, and sometimes into sash frames. Under the hammer it is
capable of being beaten into thin leaves like gold. Copper wire is much
employed by bell─hangers and other artisans. The filings of this metal
are used for giving a green colour to some kinds of artificial
fire─works.

Several preparations of copper are employed in medicine, some of them
internally, and others externally; but most of the former are violently
emetic.

_Verdigris_ is a rust or oxide (21) of copper, usually prepared from
that metal by corroding it with vinegar. There is a large manufactory of
verdigris at Montpelier in France. The workmen place alternate strata of
copper plates and husks of grapes, the latter of which speedily become
acid and corrode the metal. The verdigris, thus formed, is scraped off
as it collects on the surface; it is afterwards dried, and put in bags
or casks for sale. A manufactory of verdigris has lately been
established at Deptford, near London.

A solution of this substance in distilled vinegar affords permanent
crystals, which are improperly called _distilled verdigris_, and are
made into a green paint. Verdigris is principally consumed by dyers in
combination with logwood, for striking a black colour. It is a virulent
poison.

Oxide of copper is employed for giving a beautiful green colour to
porcelain. It also imparts the same colour to glass, and hence is
frequently employed for the formation of artificial emeralds.

                          _Alloys of Copper._

Of all metals that are known, copper is the most susceptible of alloy.
The most frequent and useful of these alloys are made with copper and
zinc, in different proportions.

_Brass_ is an alloy composed of three parts of copper, and about a
fourth part of zinc (241). It is a beautiful, useful, and well─known
yellow metal. Not being so apt to tarnish and rust as copper, and being,
in other respects, better adapted for the purpose than that metal, it is
much used for clock─work, and for mathematical and astronomical
instruments. It is more ductile than either copper or iron, and hence is
peculiarly fitted to be made into wire, for the strings of musical
instruments, and other purposes. Sieves are woven with brass wire, after
the manner of cambric weaving, and of such extreme fineness that similar
ones could not possibly be made with copper wire. Brass wire, flatted
and gilded, is sometimes made into lace. The finest brass is
manufactured at Geneva. It unites great beauty of colour to a high
degree of ductility; and is used chiefly for escapement wheels, and
other nicer parts of watch─making. For work in which there is no
friction it is necessary to cover brass with a kind of varnish or
_laquer_, to improve its colour, and prevent it from being tarnished by
exposure to the atmosphere.

_Prince’s Metal_, or _Pinchbeck_, is an alloy containing three parts of
zinc (241), and four of copper. This metal has nearly the same colour as
gold, and was formerly much in use for the manufacture of ornamental
articles of different kinds.

_Dutch Gold_ is formed by the cementation of copper─plates with calamine
(241), hammered out into leaves. This article is chiefly manufactured in
Holland and Germany, and has about five times the thickness of gold
leaf.

_Bronze_, and _the metal of which cannons are made_, consist of from six
to twelve parts of tin (238) combined with 100 parts of copper. This
alloy is brittle, heavier than copper, and of a yellow colour. Before
the method of working iron was brought to perfection, it was used by the
ancients for the manufacture of sharp─pointed instruments; and it is
supposed to have been the _æs_ or brass of the Romans.

_Bell Metal_, or the metal of which bells are formed, is usually
composed of three parts of copper and one of tin. Its colour is greyish
white; and it is very hard, sonorous, and elastic.

Bronze and bell metal are not, however, always made of copper and tin
only. They frequently have other admixtures, consisting of lead, zinc,
or arsenic. Bell─makers sometimes abuse the vulgar credulity by
pretending that they add a certain quantity of silver to the alloy, for
the purpose of rendering the bells more melodious: but they are better
acquainted with their business than to employ so valuable a metal in the
operation.

_White Copper_ is an alloy composed of equal parts of copper and arsenic
(242). The metal produced by this mixture is of a whitish colour, but
with a coppery tinge. It is freed from the latter by being melted
several times; and, by this process, is at last rendered as white as
silver. White copper is very brittle; but, if the arsenic be evaporated
by heat, it resumes its ductility, and still preserves its white colour.
When the operation is well performed, it is easy, at the first glance,
to mistake white copper for silver; but the difference may immediately
be ascertained from the properties inherent to the two metals.

White copper is employed in the manufacture of many kinds of trinkets:
and of a great number of domestic utensils; such as tea─pots,
coffee─pots, and candle─sticks.

231. _MALACHITE is a solid green copper ore, the surface of which has
frequently a bubbled appearance, and the interior is marked with
numerous irregular zones, and layers of different shades of green. It is
somewhat more than three times as heavy as water, and is so soft as to
be easily scratched by a knife._

In its appearance, malachite somewhat resembles green jasper; but it is
by no means so hard. It is, however, capable of being cut and polished
as a gem, and is manufactured into various kinds of trinkets, which of
late years have been much in request for necklaces, brooches, and
bracelets. It is also cut into slabs, and mounted into snuff─boxes. Such
is the size of which it is sometimes found, that M. Patrin saw, at
Petersburgh, a plate of malachite thirty─two inches long and seventeen
inches broad, which was valued at 20,000 livres; but the finest
specimens in Europe are some slabs that are adapted as the tops of
tables, sideboards, &c. at Trianon, in the Park of Versailles: the
largest of these are nearly four feet in length and two feet wide. They
may indeed have been formed by various pieces joined together; but, if
so, the joints are so completely concealed as not to be discoverable
even by the closest examination. Malachite is sometimes employed for the
engraving of cameos, but is seldom cut in intaglio. Smaller pieces of
this substance, that are used for trinkets, are about the same value as
carnelian. Independently of its use, in the above respects, and also as
an ore of copper, malachite, when pure, is ground into powder, and
employed as a green pigment.

The Vosges Mountains in Lorraine, and certain copper mines of Saxony,
are celebrated for producing very fine specimens of malachite. This
beautiful mineral is also found in our own country, in the copper mines
of Cornwall and Wales.

_232. TURQUOISE. The beautiful light blue substances that are called
turquoises have usually been considered as the bones or teeth of
animals, impregnated with blue oxide (21) of copper; but they are
sometimes found in nodules which are certainly not of an osseous
nature._

Turquoises are frequently set in rings, necklaces, brooches, and other
female ornaments. In Persia they are very common; and, amongst the
Turks, are held in such estimation that persons of rank almost
constantly wear them in some part of their dress, as ring─stones, and to
adorn the handles of stilettoes. They are imported into England from
Russia, stuck with pitch upon the ends of straws; because if mixed
together in parcels, the purchaser would not easily be able, in turning
them over, to observe their colour, and ascertain their value.

In the turquoise there is nothing that can recommend it to notice except
the agreeable softness of its colour, which is particularly
distinguishable by candle─light; this alone has rendered it so
fashionable as an ornament in female dress, for rings, ear─drops, and
brooches, that the demand for it is at present greater than the supply.
Imitations of turquoise are easily made in paste, and not unfrequently
imposed upon the ignorant purchaser; but in these, though the colour is
correctly given, there is a glassy lustre much higher than that of the
real stone.

Of late years a spurious kind of turquoise has also found its way into
Europe, which is much softer than the genuine kind; has more of a green
than a blue cast, and is by no means capable of so good a polish.

233. _IRON is a well─known metal, of livid greyish colour, hard and
elastic, and capable of receiving a high polish. Its weight is nearly
eight times as great as that of water._

_It is seldom found in a truly native state, but occurs, abundantly, in
almost every country of the world, in a state of oxide (21), and
mineralized with sulphuric (24), carbonic (26), and other acids._

_Iron is found in plants, in several kinds of coloured stones, and even
in the blood of animals._

Of all the metals there are none which, in the whole, are so useful, or
are so copiously and variously dispersed as iron. Its uses were
ascertained at a very early period of the world. Moses speaks of
furnaces for iron, and of the ores from which it was extracted, and
tells us that swords, knives, axes, and instruments for cutting stones,
were, in his time, all made of this metal.

The most considerable iron mines at present existing are those in Great
Britain and France. After iron ore is dug out of the earth, it is
crushed or broken into small pieces, by machinery. It is next washed, to
detach the grosser particles of earth which adhere to it. This operation
ended, it is roasted in kilns, formed for the purpose, by which the
sulphur, and some other substances that are capable of being separated
by heat, are detached. It is then thrown into a furnace, mixed with a
certain portion of limestone and charcoal, to be melted. Near the bottom
of the furnace there is a tap─hole, through which the liquid metal is
discharged into furrows made in a bed of sand. The larger masses, or
those which flow into the main furrow, are called _sows_; the smaller
ones are denominated _pigs_ of iron; and the general name of the metal
in this state is _cast iron_.

With us iron is employed in three states, of cast iron, wrought iron,
and steel.

_Cast iron_ is distinguishable, by its properties of being, in general,
so hard as to resist both the hammer and the file; being extremely
brittle, and for the most part, of a dark grey or blackish colour.

A great number of useful and important articles are formed of cast iron,
such as grates, chimney backs, pots, boilers, pipes, and cannon shot.
These are made by casting ladles full of the liquid metal into moulds
that are shaped, for the purpose, in sifted sand.

_Wrought iron._ The process of converting cast iron into wrought or
malleable iron, is called _blooming_. The cast iron is thrown into the
furnace, and kept melted by the flame of combustibles which is made to
play upon its surface. Here it is suffered to continue for about two
hours, a workman constantly stirring it, until, notwithstanding the
continuance of the heat, it gradually acquires consistency, and
congeals. It is then taken out, while hot, and violently beaten with a
large hammer worked by machinery. In this state it is formed into bars
for sale.

The value of iron is beyond all estimate, and infinitely greater than
even that of gold. By means of this metal the earth has been cultivated
and subdued. Without it houses, cities, and ships, could not have been
built; and few arts could have been practised. It forms also the
machinery by which the most useful and important mechanical powers are
generated and applied.

_Steel_ is usually made by a process called _cementation_. This consists
in keeping bars of iron in contact with powdered charcoal, during a
state of ignition, for several hours, in earthen troughs, or crucibles,
the mouths of which are stopped up with clay. Steel, if heated to
redness, and suffered to cool slowly, becomes soft; but if plunged,
whilst hot, into cold water, it acquires extreme hardness. It may be
rendered so hard as even to scratch glass; and at the same time, it
becomes more brittle and elastic than it was before. Although thus
hardened, it may have its softness and ductility restored, by being
again heated, and suffered to cool slowly. A piece of polished steel, in
heating, assumes first a straw─yellow colour, then a lighter yellow,
next becomes purple, then violet, then red, next deep blue, and at last
of all bright blue. At this period it becomes red hot, the colours
disappear, and metallic scales are formed upon, and encrust its surface.
All these different shades of colour indicate the different tempers that
the steel acquires by the increase of heat, from that which renders it
proper for files, to that which fits it for the manufacture of watch
springs. Mr. Stoddart has availed himself of this property to give to
surgical, and other cutting instruments, those degrees of temper which
their various uses require.

The kind of steel which has been most celebrated in this country is that
imported from Syria under the name of _Damascus steel_. Germany is also
noted for its steel. The best steel manufactured in Britain is known by
the name of _cast steel_; and the making of it, although it was long
kept a profound secret, is now discovered to be a simple process. It
consists merely in fusing it with carbonat of lime (140), or in what is
called cementation, with charcoal powder, in a peculiar kind of furnace.
The iron produced in Sweden is considered superior to that of any other
country in Europe for the manufacture of steel.

All kinds of edge tools, where excellence is required, are made of
steel; and a steel instrument may be immediately known from an iron one,
by letting fall upon it a drop of nitric acid or aqua fortis (206),
somewhat diluted with water. If it be steel, this will occasion a black
spot; but if it be iron, it will not have this effect. Steel is
attracted by the magnet, and is capable of receiving a permanent
_magnetic property_, which has led to the discovery of the mariner’s
compass. Had iron been productive of no other advantages to mankind than
this, it would on this account alone have been entitled to their
greatest attention.

Iron, when exposed to the moisture of the atmosphere, becomes gradually
covered with a brown, or yellowish substance, known by the name of
_rust_, which, if suffered to continue without interruption, will
corrode the entire substance of the iron. The rust or oxide of iron (21)
is a substance in considerable request by calico printers for a dye.
_Iron─moulds_ are spots on linen occasioned by its exposure to iron in
damp situations; these are removeable only by the application of an
acid.

There are various modes of _preserving iron and steel_ from rust. The
following is recommended by an eminent French chemist as one of the
best. Mix copal varnish, made greasy with oil, with about four─fifths of
the best spirit of turpentine. Apply this by means of a sponge, over the
whole surface, and allow it to dry. This varnish may be successfully
used for all the metals; and particularly for the preservation of such
philosophical instruments as, by being brought into contact with water,
are liable to lose their splendour, and become tarnished.

234. _METEORIC STONES are a species of iron ore, which have at different
times been known to fall from the atmosphere._

_They have been seen only in shapeless masses, of from a few ounces to
several hundred pounds in weight. Their texture is granular. They are
covered externally with a thin blackish crust, and are, internally, of
an ashy grey colour, mixed with shining minute particles._

There is sufficient evidence to show that solid masses of stone have
been observed to fall from the air at a period considerably anterior to
the Christian era. Notwithstanding this, so very extraordinary was the
phenomenon, that, until the year 1802, it was generally regarded by
philosophers as a vulgar error. Mr. Howard, in that year, submitted to
the Royal Society a paper which contained an accurate examination of the
testimonies connected with events of this kind; and described a minute
analysis of several of the substances which had been said to have fallen
in different parts of the globe. The result of his examination was that
all these stony bodies differ completely from every other known stone;
that they all resemble each other, and are all composed of the same
ingredients.

The greatest number of the stones which have fallen from the air have
been preceded by the appearance of luminous bodies or meteors. These
meteors have burst with an explosion, and then the shower of stones has
fallen to the earth. Sometimes the stones have continued luminous until
they sunk into the earth, but most commonly their luminousness
disappeared at the time of the explosion. Their motion through the air
is surprisingly rapid, in a direction nearly horizontal; but they seem
to approach the earth before they explode. In their flight they have
frequently been heard to yield a loud whizzing sound. They are hot when
they first reach the earth; and exhibit, on their surface, visible marks
of fusion.

A general tradition has prevailed in almost all ages, and amongst all
people, of the fall of solid bodies from the atmosphere, under various
denominations, but, with us, more particularly, under that of
_thunderbolts_. In barbarous and uncivilized countries, these have
usually been ascribed to the miraculous judgment of the deity; and they
may be considered as the true origin of the worship of stones. The image
of Diana, mentioned in the Acts of the Apostles, as believed by the
Ephesians to have fallen down from Jupiter, and the Palladium or sacred
statue of Minerva, which also is said to have fallen from Heaven, and to
have been preserved in Troy, as a treasure, on the safety of which that
of the city depended, had each, no doubt, this origin. The Psalmist
evidently alludes to the falling of meteoric stones, when, speaking of
the Almighty, he says, “He made darkness his secret place; his pavilion
round about him with dark water, and thick clouds to cover him. At the
brightness of his presence his clouds removed; hailstones and coals of
fire. The Lord also thundered out of Heaven, and the Highest gave his
thunder; hailstones and coals of fire.”

Among numerous other instances of these stones, it is recorded that, on
the seventh of November, 1492, betwixt eleven and twelve o’clock at
noon, a dreadful clap of thunder was heard at Ensisheim, a considerable
town in Alsace, and that a huge stone was seen to fall on a field lately
sown with wheat. On several of the neighbours going to the place, the
hole it had formed was found to be about three feet in depth, and the
stone when dug out, weighed two hundred and sixty pounds. It was
preserved in the cathedral of Ensisheim until the beginning of the
French Revolution, when it was conveyed to the public library at Colmar.
There are in the British Museum two small pieces of this stone, and
fragments of several other meteoric stones which have fallen in
different parts of the world.

Two stones fell near Verona in Italy, in the year 1672, one of which
weighed three hundred, and the other two hundred pounds.

Mr. Sowerby, the publisher of English Botany, and of several other
highly estimable works, possessed a meteoric stone which fell near Wold
Newton in Yorkshire, in the afternoon of the thirteenth of December,
1795, and weighed fifty─six pounds. Whilst this stone was in motion
through the air, several persons perceived a body passing along the
clouds, although they were unable to ascertain what it was. It passed
over several different villages, and was also accurately and distinctly
heard. The day was foggy; and, though there was some thunder and
lightning at a distance, it was not until the stone fell that an
explosion took place which alarmed all the adjacent country; and
created, distinctly, a sensation that something very extraordinary had
happened. A shepherd belonging to Captain Topham was within a hundred
and fifty yards of the place where it fell; George Sawden, a carpenter,
within sixty yards; and John Shepley, one of Captain Topham’s farming
servants, was so near that he was forcibly struck by some of the mud and
earth that were raised by the stone dashing into the ground. In its fall
the stone excavated a place nineteen inches in depth (seven inches of
which were in a solid rock of chalk), and somewhat more than three feet
in diameter, fixing itself so firmly that some labour was required to
dig it out.

Another stone of considerable size fell in Scotland on the fifth of
April, 1704. A misty commotion was observed in the atmosphere, and,
nearly at the time of the stone falling, a report was heard as loud as
if three or four cannon had been fired at a little distance. The report
was succeeded by a violent rushing or whizzing noise; and, almost
immediately afterwards, the stone fell into a drain, in the presence of
two men and two boys, splashing the water to a distance of twenty feet
around. The stone, when dug out, was found to have sunk about eighteen
inches into the earth.

On the fifth of November, 1814, about half past four o’clock in the
afternoon, a dreadful peal of thunder was heard in the Doab in Persia,
and was immediately succeeded by a shower of large stones, many of them
from twenty─six to thirty pounds weight each. Several inhabitants of the
adjacent country were present at the time; and not fewer than nineteen
of the stones were collected.

Professor Pallas, many years ago, discovered lying on the surface of a
hill in Siberia, a mass of native iron, which weighed 1680 pounds. It
was considered by the natives as a holy relic, and was believed by them
to have fallen from heaven. M. de Bougainville, the French
circumnavigator, discovered, on the banks of the river La Plata, in
South America, an enormous mass of native iron, which he calculated to
have weighed about 100,000 pounds. And a mass of native iron, appearing
in every respect to have been of meteoric origin, was, some years ago,
discovered in the district of St. Jago del Estro, in South America. It
was in the middle of a great plain, and had no rock nor mountain near
it, and was calculated to have weighed about thirty tons.

The origin of meteoric stones is involved in great obscurity. Some
writers have imagined that they might be projected from distant
volcanoes; others, that they may have been detached from rocks, and had
their substance considerably changed by a concurrence of natural causes;
others, that they may have been generated in the air by a combination of
mineral substances; and others, that they may have been projected from
the moon. The latter was the opinion of La Place the astronomer, who
says that a mass, if thrown by a volcano from the moon, with a velocity
of about a mile and half per second, it will thence be projected beyond
the sphere of the moon’s attraction, and into the confines of that of
the earth; the consequence of which will be, that the mass must
presently fall to the earth, and become a part of it.

235. _LOADSTONE, or MAGNETIC IRONSTONE, is a compact blackish kind of
iron ore, which is possessed of the power of attracting iron, as well as
every substance which contains ferruginous particles. It is betwixt four
and five times as heavy as water._

This mineral is found in masses of different form and size in most of
the iron mines of Europe and America, and, when submitted to the
furnace, it yields a considerable proportion of metal. It makes
excellent bar iron, but very indifferent cast iron. In Sweden, and
particularly at Roslager, magnetic iron stone is found quite pure, and
the iron that is wrought from it is imported in considerable quantities
into Great Britain, for the purpose of being manufactured into steel.

The appellation of load, or leading stone, has been given to this kind
of iron from its magnetic virtues; for it is not only endowed with the
property of attracting iron, but also of pointing itself, and even
enabling a needle touched with it to point, towards the poles of the
world. We are, however, entirely ignorant what is the cause of this very
extraordinary property.

Artificial magnets, constructed of steel, not only possess all the
essential virtues of the genuine loadstone, but even in a much higher
degree. The natural magnet is consequently now little esteemed except as
an object of curiosity.

236. _PYRITES, or MARCASITE, is a mineral substance, formed by a
combination of iron with sulphur._

_It is usually of a bronze, yellow, or brownish colour, very various in
form, being massive, globular, club─shaped, oval, or crystallized; and
so hard as to strike fire with flint._

Few minerals are more common than this, as it occurs, in some state or
other, in almost every rock and vein. It is often found among coals;
and, when heated, decrepitates with a loud unpleasant noise and
sulphureous smell. To the decomposition of this mineral it is that the
hot temperature of almost all the mineral waters may be ascribed.

The name of pyrites, which in the Greek language signifies _firestone_,
has been obtained by this mineral from its property of striking sparks
from steel. It was formerly used for fire─arms, as we now use flints. In
commerce it is known by the name of marcasite. Some years ago it was
much used, particularly in France, for the making of buttons and
buckles; and was cut and polished, by lapidaries, for trinkets,
particularly for the rims and hands of watches, and various kinds of
female ornaments. If skilfully cut in the form of small rose diamonds,
although an opaque substance, it has somewhat the appearance of a
diamond. In the tombs of the Peruvian princes, with whom a considerable
portion of their valuables was always interred, there have been found
polished plates of marcasite, which appear to have served them as
mirrors.

This mineral is never worked as an ore of iron; and it is principally
valued on account of the sulphur which can be obtained from it by means
of heat; and the green vitriol, or copperas (208), which it affords by
exposure to the air.

Ignorant persons frequently mistake iron pyrites for gold; but it is
easily distinguished from that precious metal by its brittleness. It
breaks when hammered, whereas gold is malleable, or may be extended by
hammering: it also strikes fire with steel, which gold will not.

237. _RED OCHRE, REDDLE, or RED CHALK, is an iron ore of blood─red
colour, which is sometimes found in powder, and sometimes in a hardened
state. It has an earthy texture, and stains the fingers when handled._

The principal use of red chalk is for drawing: the coarser kinds are
employed by carpenters and other mechanics, and the finer kinds by
painters. For the latter purpose it should be free from grit, and not
too hard. In order to free it from imperfections, and render it better
for use, it is sometimes pounded, washed, mixed with gum, and cast into
moulds of convenient shape and size.

Under the name of reddle, this substance is much used for the marking of
sheep; and (when mixed with oil) for the painting of pales, gates, and
the wood─work of out─buildings.

Another kind of iron ore, or rather a compound of the ores of iron and
manganese, is called _umber_. This mineral, which is of a brown colour,
is found in beds in the island of Cyprus, and is used as a kind of paint
both in a raw state and burnt.

238. _TIN is a white metal, somewhat like silver in appearance, but is
considerably lighter, and makes a squeaking or crackling noise when
bent. It is very soft and ductile, and has but little elasticity._

_This metal is always found either in a state of oxide (21), or in
combination with sulphur and copper; and is about seven times as heavy
as water._

The principal tin mines which are known to us are those of Cornwall,
Devonshire, Germany; the island of Banca, and peninsula of Malacca, in
India; and Chili and Mexico in America. Of these the most celebrated are
the mines of Cornwall, which are known to have been worked before the
commencement of the Christian era. Diodorus Siculus, who wrote forty
years before the birth of Christ, gives an account of these mines, and
says that their produce was conveyed to Gaul, and thence to different
parts of Italy. This species of metal was used in the time of Moses, and
is mentioned in the writings of Homer.

Tin is found in veins, or beds, but chiefly in veins, running through
granite and other rocks. In some of the valleys and low grounds of
Cornwall, the tin ore is found in rounded grains and masses. In these
situations, small grains of gold are sometimes found with it. To
separate the tin from earthy and other matters with which it is
intermixed, streams of water are passed over them; and these deposits
have the name of _stream─works_.

When the tin ore has been dug from the earth, or has been collected at
these stream─works, it is thrown into heaps, and broken to pieces. After
this it is washed, and subsequently roasted in an intense heat, for the
purpose of dissipating some of the substances with which it is combined.
It is lastly melted in a furnace, and thereby reduced to a metallic
state. The metal is then poured into quadrangular moulds of stone, each
containing about 320 pounds weight. These have the denomination of
_block─tin_, and are stamped by officers of the Duke of Cornwall, with
the impression of a lion, the arms of that duchy. This is rendered a
necessary operation before the tin can be offered for sale; and on
stamping, it pays a duty of four shillings per hundred weight to the
Prince of Wales, as Duke of Cornwall, who thence derives a very
considerable income.

The article usually called _tin_, or _tin─plate_, and, in Scotland,
_white iron_, of which saucepans, boilers, drinking vessels, and other
utensils of domestic economy are made, consists only of thin iron plate
coated with tin. It is thus formed. The iron plates are immersed in
water rendered slightly acid by spirit of salt (muriatic acid, 202) or
spirit of vitriol (sulphuric acid, 211): after which, to clean them
completely, they are scoured quite bright. These plates are then each
dipped into a vessel filled with melted tin, the surface of which is
covered with suet, pitch, or resin, to prevent the formation of dross
upon it. The tin not only covers the surface of the iron, but completely
penetrates it, giving to its whole substance a white colour.

In a manner similar to this, stirrups, buckles, bridle─bits, and other
articles, are tinned.

Iron is usually tinned before, but copper always after it has been
formed into utensils. The object to be attained by the tinning of copper
is to prevent the vessels made of that metal from being corroded, and to
preserve the food prepared in them from being mixed with any particles
of that poisonous substance called verdigris, which is formed by such
corrosion. In the tinning of copper vessels, their interior surface is
first scraped very clean with an iron instrument, and then rubbed over
with sal─ammoniac (207), for the purpose of more completely cleansing
them, and also of preventing the formation of verdigris from the copper
during the operation. The vessel is then heated, and a little pitch is
thrown into it. While quite hot, a piece of tin is applied to the
copper, and this, instantly uniting with it, soon clothes the whole
surface with tin.

This metal, when amalgamated with mercury, is used for the silvering of
looking─glasses (228). When tin is melted in an open vessel, its surface
is soon found to be covered with a grey powder, which is an oxide (21)
of the metal, and is generally called _dross_. If the heat be continued,
the colour of this powder becomes yellow. In this state it is known by
the name of _tin─putty_, and is employed in polishing glass, steel, and
other hard substances. When the heat is very violent, the metal takes
fire, and is converted into a fine white oxide, which is used to render
glass opaque, for the forming of enamel. Oxide of tin is also an
important article to dyers. It is employed by them, in large quantities,
to give brightness to such colours as are used in forming scarlets and
other reds: and to precipitate the colouring matter of other dyes.

Tin is an essential ingredient in _bell─metal_, _bronze_, _pewter_, and
various other compounds. It may be combined with lead, in any
proportion, by fusion; and this alloy is harder, and possesses much more
tenacity than tin. The hardest alloy is a composition of three parts of
tin and one of lead. The presence of the tin destroys, in a great
measure, the noxious qualities of the lead. It is sometimes customary to
tin copper vessels with this mixture, and it has been ascertained that
such vessels are in no respects injurious.

There are three kinds of _pewter_ in common use. These are called
_plate_, _trifle_, and _ley pewter_. The first, which is made into
plates and dishes, is formed of tin, with a small proportion of lead and
antimony (245). The second, or _trifle pewter_, which is made in
somewhat different proportions, is used for the quart and pint pots of
the publicans: and the _ley pewter_, which is formed of three parts of
tin and one of lead, is manufactured into wine and spirit measures.

Tin may be beaten into leaves or plates that are much thinner than
paper. But, when it is thus worked, several leaves must be joined
together. They then support each other, and yield to the hammer without
tearing. These leaves are used for the silvering of glass globes, and
the plating of other metals. Those that are used for the silvering of
looking─glasses are much thicker. The article called _tin─foil_ is an
alloy, consisting generally of two parts of tin and one of lead; and
capable of being beaten to less than the thousandth part of an inch in
thickness.

239. _LEAD is a heavy metal, of pale and livid grey colour when broken,
not sonorous when pure, very flexible, and so soft that it may be marked
with the nail. It stains paper or the fingers of a bluish colour, and is
about eleven times heavier than water._

T_he most common state in which lead is found is in combination with
sulphur and a small portion of silver. This ore is known by the name of_
galena, _and is frequently in the form of blackish cubical crystals.
Lead is also found in union with arsenic (242) and many acids._

Great Britain possesses the most important lead─mines in the world; and
those that are best known are in the counties of Flint and Derby. The
latter are supposed to have been worked even in the time of the Romans.

Lead mines are entered sometimes by perpendicular shafts, and sometimes
(when in the sides of hills) by levels. In some of the Derbyshire mines,
where the depth of the veins will admit of it, the men work, at
different heights, of from four to six feet above each other, along what
are called stoops; the uppermost men being two or three yards before
those next in succession, and thus forming a kind of steps. The
implements used are picks, hammers, and strong iron wedges; and the
rocks are also frequently loosened by means of gunpowder.

When the ore is brought out of the mine, it is sorted and washed, to
free it from dirt and rubbish. After this it is spread on a board; the
best pieces are picked out and separated; and those containing ore mixed
with spar (194) or other substances, are placed separate, to be broken,
and again picked. After the ore, by pickings and washing, has been
sufficiently cleansed from extraneous matters, it is roasted in a kind
of kiln to free it from the sulphur that is combined with it. The next
process is to mix it with a certain quantity of coke, charcoal, or peat,
and submit it to the smelting furnace. In this furnace there are
tap─holes, which, when the lead is melted, are opened, and the metal, in
a fluid state, runs into a large iron pan. The dross which floats on its
surface is now skimmed off; and the metal is taken out by ladles, and
poured into cast iron moulds, with round ends. The lead thus formed, is
ready for use, and has the name of _pig lead_. According to their size,
the pieces that are thus cast have the appellation of _pigs_, and
_half─pigs_.

Lead is mentioned in the Sacred Writings; and is described by Homer as
in common use at the period of the Trojan war. The ancients seem to have
considered it as nearly allied to tin. The Romans employed it to sheathe
the bottoms of their ships, fastening it to the planks and timbers by
nails made of bronze.

When first melted, lead is bright, but it soon tarnishes by exposure to
the air. It melts at a temperature very low in comparison with most
other metals; and when a strong heat is applied, it boils and
evaporates.

Lead is much employed in the useful arts. When rolled between iron
cylinders to a requisite state of thinness and uniformity, it is used
for the covering of houses and churches, notwithstanding the danger, in
case of fire, to persons within, who are exposed to a shower of burning
metal. It is cast into pipes, cisterns, and reservoirs for water, as
well as into large boilers for chemical purposes. But all culinary or
domestic vessels made of lead, particularly if intended for the keeping
of acid liquors, should carefully be avoided, as the surface of the lead
is thereby corroded, and the liquid contained in them is rendered
poisonous. Hence arises that dreadful complaint, too well known where
cyder is kept in leaden cisterns, called the _Devonshire colic_; hence
also the injury which sometimes follows from the use of lead in the
glazing of coarse earthenware.

Great quantities of lead are consumed for the making of _shot_. For this
purpose the metal is alloyed with arsenic (242), to render it more
brittle; and to render the grains more round and perfect than they
otherwise would be. Shot is formed by dropping the melted alloy into
water, through an iron or copper frame, perforated with round holes,
according to the size required. For the smallest shot the elevation is
about ten feet above the water; and for the largest about a hundred and
fifty feet.

An alloy of lead and tin, in the proportion of two parts of lead and one
of tin, forms the _solder_ which is used by plumbers. The _types_ that
are used by printers for very large characters are sometimes composed of
an alloy of lead and copper. Lead is also used, with tin, in the
manufacture of _pewter_.


                           _Oxides of Lead._

The different oxides (21) of lead are easily soluble in oil, and
consequently are of great use to painters. Of these the following are
the most important:

_White Lead_, or _Ceruse_.—This is made by suspending thin plates of
lead over heated vinegar, in such manner that the vapour which rises
from the acid may circulate about the plates. By this process the plates
become at length entirely corroded, and converted into a heavy white
powder. The manufacture of white lead is a most unhealthy trade, and is
confined to a few persons, who have large conveniences for the purpose.
This substance, when mixed with oil, is used as a paint for wood─work
both of the outsides and insides of buildings. The fumes that are
emitted from white paint are extremely noxious. Persons who breathe them
are frequently seized with pains, and experience symptoms not much
unlike those that precede palsy; and the danger which attends the
inhabiting of apartments recently painted is well known. The odour of
vinegar will correct the pernicious effect of these exhalations, by
acting as a solvent, and combining with, and precipitating them. We are
informed that white lead, dangerous as it is, was in great request among
the Roman ladies as a cosmetic. It is sometimes used as an external
application for ulcers and other kinds of sores.

_Massicot_ is a mineral substance of yellow colour, used for painting,
and prepared from the dross or pellicle that is formed by the melting of
lead.

_Red Lead_, or _Minium_, is a mineral substance of red colour, used for
painting, and made, by a tedious and troublesome process, from massicot.
For this purpose the massicot is ground to a fine powder, put into a
furnace, and constantly stirred, whilst the flame of the burning coals
plays against its surface for about forty─eight hours, when it is
converted into a red powder, which is the article under consideration.
It is subsequently passed through very fine iron sieves. The use of red
lead as a pigment is well known; but as it is liable to turn black,
vermilion is generally preferred to it. It is sometimes employed in
medicine as an external application for abating inflammations, for
cleansing and healing ulcers, and the like; and is used in the
manufacture of glass.

_Litharge_ is another kind of oxide of lead. This is prepared by
exposing calcined lead to a brisk fire for a certain length of time. The
substance, on cooling, concretes into a flaky matter. Litharge is used
by potters for the glazing of earthenware, but vessels that are glazed
with it are thereby rendered unwholesome. It is also employed, in the
composition of the finer kinds of glass, for the purpose, not only of
giving them greater transparency, but also of rendering them capable of
sustaining sudden changes from heat to cold, and of giving to them a
susceptibility of being cut without breaking. It, however, adds
considerably to the weight of the glass.

_Litharge Plaster_, or _Diachylon Plaster_, as it is more frequently
called, is prepared by boiling two pints of olive oil with one pint of
litharge, adding water, and constantly stirring the mixture till they
are duly incorporated. This plaster is applied in excoriations of the
skin, slight wounds, and other sores.

_Sugar of Lead_ is a preparation either from the metal itself, or from
white lead and distilled vinegar. It is usually observed in the form of
small slender crystals, which have a glossy appearance like satin. This
substance is employed, in considerable quantity, by dyers and calico
printers; and is the basis of a liquid frequently used in medicine,
called _Goulard_, or _Goulard’s Extract_. Although in itself a most
virulent poison, it is often used by unprincipled dealers for correcting
the rancidity of oil of almonds and olive oil; and a similar pernicious
fraud is practised by dissolving a portion of it in wines which are
becoming acid, in order to correct their acidity. These frauds, however,
are easily detected by preparations or tests, which are sold by chemists
for that purpose. Perhaps the best and simplest test is Harrowgate
water: a little of this poured into the suspected compound will discover
the presence of lead by giving to the fluid a dark brown or blackish
tinge.

The following is a pleasing experiment. Dissolve an ounce of sugar of
lead in about a quart of water; filter the solution through a piece of
blotting paper, and put it into a glass decanter, suspending in it a
piece of zinc by a brass wire. A decomposition will take place; the lead
will be set at liberty, and will attach itself to the zinc, forming
there a sort of metallic tree.

                  *       *       *       *       *

It has been stated that silver is usually a component part of lead ore.
To disengage this, where the quantity is sufficient to repay the
expense, the lead, after it has been smelted, is subjected to the action
of what is called a refining furnace. A continued blast of fresh air is
thrown upon its surface by means of large bellows, while the lead is
kept in a state as intensely hot as possible. This by degrees converts
the lead into a yellow scaly oxide or dross. The oxide, thus formed, is
driven off from the melted metal as it rises, and the silver is left
alone at the bottom, in a metallic state. After the operation is
complete, the oxide is fused with charcoal, and again reduced to
metallic lead.

                  *       *       *       *       *

We must not omit to mention that, in some of the mines of Derbyshire,
there is a singular variety of lead ore called _slickenside_. This is a
kind of galena, which presents, to the eye, a smooth and bright surface,
appearing as if it were plated. Sometimes it forms the sides of
cavities; and it has the extraordinary property, when merely pierced
with the miner’s tool, of rending with great violence, and exploding
with a crackling noise. Some miners, fearless of danger, venture to
scratch it with their tools; and, on coming again to the spot, they
often find that, during their absence, the slickenside has exploded, and
fallen off in considerable quantity. Sometimes, however, they suffer for
their imprudence. Mr. Mawe, in his account of the Mineralogy of
Derbyshire, says, that he has seen a man come out of a mine cut
violently, as if he had been stabbed about the neck and in other parts
of the body, in consequence of the explosion of slickenside which he had
pierced. The cause of this extraordinary phenomenon has not been
explained.

240. _NICKEL, when pure, is a fine white metal, somewhat resembling
silver in appearance, but it is attracted by the magnet, and has itself
the property of attracting iron._

_It is ductile and malleable, difficult of fusion, and about nine times
heavier than water. This metal is always mixed with arsenic (242) and
iron._

Nickel is found in Cornwall, and in some other counties of England; in
Germany, Sweden, France, Spain, and several parts of Asia. The Chinese
employ it in making white copper; and, in conjunction with copper and
zinc, they manufacture it into various kinds of children’s toys. Nickel
gives a certain degree of whiteness to iron. It is used, with advantage,
by some of the Birmingham manufacturers, in combination with that metal,
and by others in combination with brass. If it were possible to discover
an easy method of working nickel, there can be little doubt but it would
be found a very valuable metal for surgical instruments, for compass
needles, and other articles, as it is not, like iron, liable to rust.
When nickel is freely suspended, it points to the north and south, in
precisely the same manner as the common magnetic needle.

Oxide of nickel is used for giving colours to enamels and porcelain. In
different mixtures it produces brown, red, and grass─green tints.

241. _ZINC, or SPELTER, as it is sometimes called, is a bluish white
metal formed in thin plates adhering together. It has a very perceptible
taste, is about seven times heavier than water, rather harder than
silver; and possesses but a small degree of malleability and ductility,
except under certain circumstances._

_This metal is never found in a pure state; and the principal ores from
which it is procured are known by the names of_ Calamine _and_ Blende.
_Of these the former is an oxide (21) of zinc combined with carbonic
acid (26), and the latter is a combination of zinc with sulphuric acid
(24)._

The ores of zinc are very abundant in many countries. We are informed
that nearly the whole of Flintshire in North Wales abounds with
calamine; and that, so entirely ignorant were the inhabitants of its
use, as, till after the middle of the eighteenth century, to have even
mended their roads with it. These roads, however, have since been turned
up in many places, and the materials have been converted to more
valuable purposes. Derbyshire affords a great quantity of the ores of
zinc, particularly calamine. This is found at various depths, generally
in beds of yellow, or reddish brown clay, and usually near some vein of
lead ore.

The mode of extracting zinc from its ore is by distillation. The process
adopted, in some parts of Saxony, is equally simple and ingenious. An
inclined stone is placed near the anterior part of a furnace, in which
the ore of lead containing zinc is fused. A great part of the zinc
condenses upon this stone, and flows, in drops or globules, into a
quantity of charcoal placed at the bottom to receive it. These globules
are afterwards again melted, to run the metal into a mass.

When exposed to the air, the surface of zinc is soon tarnished, but it
scarcely undergoes any other change. It has a certain degree of
ductility. When heated a little above 218° of Fahrenheit, it is
malleable; and, when annealed, may be passed through rollers, and formed
into thin sheets or leaves. Although, previously to being thus heated,
it is brittle; on now cooling, it continues soft, flexible, and ductile.
The inconvenience arising from the brittleness of the zinc being
removed, this metal is applicable to many useful purposes. It may even
be drawn into wire, but the tenacity of this is not great: a piece of
zinc wire, one tenth of an inch in diameter, will sustain only a weight
of twenty─six pounds without breaking. It has been proposed to
substitute zinc in the place of tin for the lining of copper vessels;
but it has not hitherto been ascertained whether this can be done with
effect, and without injury. Prizes have of late been offered, to a
considerable extent, in France, for the ascertainment of this fact. In
China, zinc is employed as a current coin of the country; and for this
purpose it is used in the utmost purity. The Chinese also, as well as
the artists of our own country, employ it to a great extent in various
alloys. It is used in the manufacture of _brass_, _pinchbeck_ or
_prince’s metal_, and _bronze_, all of which consist of this metal in
combination with different proportions of copper (230). _Tutenag_ is a
well known white metal, made principally of zinc, and used for forming
candlesticks and other articles. When tutenag is well manufactured, it
is of good colour, and not more disposed to tarnish than silver. Zinc is
one of the metals employed to form the galvanic or voltaic apparatus;
and its filings are mixed with gunpowder, to produce those brilliant
stars and spangles which are seen in the best kinds of artificial
fire─works. Preparations of zinc are occasionally used in medicine. If a
thin plate of zinc be applied to the upper surface of the tongue, and a
shilling to the lower surface, and both metals, after a little while, be
brought into contact, a very peculiar taste will, at that instant, be
perceived. The same sensation will be perceived, though in a weaker
degree, if the silver be placed at the top and the zinc at the bottom.

If a silver probe be introduced high up one of the nostrils, and be
brought into contact with a piece of zinc placed on the tongue, a
sensation not unlike that of a strong flash of light will be produced in
the corresponding eye. A similar perception will result, both at the
moment of contact and that of separation, if one of the metals be
applied as high as possible between the gums and upper lip, and the
other in a similar situation with the under lip, or even under the
tongue.

A white oxide (21) prepared from zinc, was, some years ago, proposed as
a substitute for white lead in house painting. This oxide is not
dangerous in its application; and does not become yellow when mixed with
oil. But these advantages are counterbalanced by some defects, which
have hitherto caused it to be rejected. It is lighter than white lead:
does not cover the surface so equally, nor so well; and is of
considerably higher price.

CALAMINE.—The principal use of calamine is in the manufacture of brass
(230); and the mines of Derbyshire, and of Limbourg in the Netherlands,
supply with this mineral nearly all the brass works in Europe. After the
calamine is dug out of ground, it is reduced to pieces not in general
larger than a nut. It is then roasted for five or six hours, in what is
called a reverberating furnace. The large pieces are separated, and the
small ones are passed through a sieve. It is washed; and, when dry, is
ground in a mill. In this state it is sold. The principal demand for it
is at Birmingham, for the different brass founderies in that town.

The use of calamine in the composition of brass was known at a very
early period. It is mentioned by Aristotle, who also makes a distinction
between the compound resulting from the mixture of copper and calamine
or brass, and that resulting from the mixture of copper and tin or
bronze.


────────────────────────────────────────────────────────────────────────




                       ORDER II.—BRITTLE METALS,


OR SUCH AS ARE NOT CAPABLE OF BEING FLATTENED OR ELONGATED BY THE HAMMER
  WITHOUT TEARING OR BREAKING.

242. ARSENIC, _in a metallic state, has a bluish white colour, and
considerable brilliancy; it is remarkably brittle, is the softest of all
known metals, and is somewhat more than eight times heavier than water._

_It is found nearly pure, and in considerable abundance, in different
parts of Germany; usually occurring in masses of various shapes, and in
combination with a small portion of iron, gold, or silver._

_The arsenic sold in the shops, and too well known for its poisonous
qualities, is an oxide (21) of this metal artificially prepared._

In some mines on the Continent arsenic is very abundant, and is found
extremely injurious to the workmen. Being very volatile, its fumes
affect and destroy the lungs, and occasion death in a short time to many
of them. One of its ores, _arsenical pyrites_, is found abundantly in
Cornwall and Devonshire, accompanying ores of copper and tin; and, in
combination with other metals, it occurs, in a greater or less
proportion, in almost all mines.

Arsenic is occasionally used in the arts. It is employed in various
metallic combinations where a white colour is required, and,
particularly, for the whitening or bleaching of copper, which is thereby
also rendered capable of taking a fine polish; hence its use in many of
the compositions for the mirrors of reflecting telescopes, and for other
optical instruments. The manufacturers of glass frequently employ the
oxides of arsenic in the fabrication of that article. Arsenic is used in
the processes of dyeing and calico printing; and for the imparting of
different artificial shades and colours to furs. It is also used in the
manufacture of small shot, from its rendering the lead more brittle, and
better capable of being formed into grains, than it would be without
such admixture.

The arsenic of commerce is prepared to a great extent in Bohemia and
Saxony, by roasting cobalt ores for the manufacture of zaffre (247).
_White arsenic_ is made, by mixing the common oxide with potash, and
submitting it to a certain degree of heat, in vessels adapted to the
purpose; the arsenic, rising in fumes, is separated, leaving the sulphur
behind, united to the potash. This process is called sublimation.

Of all substances with which we are acquainted this is perhaps the most
deadly. If only a few grains of it be taken into the stomach, it proves
fatal; and it has frequently proved the more injurious from its
deceitful appearance, in which it somewhat resembles salt or white
sugar. Carelessly left in places open to the access of children, arsenic
has not unfrequently been mistaken by them for sugar, and has been
attended with the most dreadful consequences. If thrown on heated coals,
however, it is immediately known, by the smell of garlic, and the white
fumes which it gives out. The best remedy for this poison is said to be
a few scruples of liver of sulphur (sulphuret of potash), dissolved in
half a pint or a pint of water, and administered a little at a time, as
the patient can bear it.

Notwithstanding its deleterious qualities, arsenic is occasionally used
in medicine, though in extremely small doses; and it has, in particular,
been found efficacious in many cases of intermittent fever.

It is employed as a poison for rats and mice; and, diluted with water,
it attracts and poisons flies, whence it is sometimes called by the
French, _poudre a mouches_. There cannot, however, be too great caution
used either in the preparation, or in the application, of this fatal
poison.

243. _YELLOW ORPIMENT is a mineral substance of lemon colour, which
consists of arsenic in combination with sulphur; and in the proportion
of about fifty─seven parts of the former and forty─three of the latter._

_It is about thrice as heavy as water; and is found both in a massive
and crystallized state; but the crystals are so confused that their
figures cannot easily be determined._

The orpiment of commerce is an artificial production, and is chiefly
imported from different parts of the Levant. The Turks, and other
Orientals, use it in the depilatories which serve to render bald the top
of the head. A very beautiful, but fugitive pigment, called _King’s
yellow_, is prepared from this mineral; and other preparations of
orpiment are occasionally used by painters, and also by dyers and calico
printers. The whole of these, however, are extremely poisonous.

Orpiment is found in a natural state, along with copper and other ores,
in Natolia, Servia, Hungary, Turkey, and some other countries.

244. _REALGAR, or RED ORPIMENT, is a mineral substance of red or orange
colour, which consists of arsenic in combination with sulphur; and in
the proportion of seventy─five parts of the former, and twenty─five of
the latter._

_It is somewhat more than three times as heavy as water; and occurs
sometimes in a crystallized, and sometimes in a massive or disseminated
state._

This production, which, by ignorant persons, is not unfrequently
mistaken for red lead, is in considerable request by painters, dyers,
and calico printers. In China it is manufactured into small pagodas and
other ornaments. And the Chinese form it into medical cups, and use
lemon juice which has stood for some hours in them, as a cathartic.
Realgar is poisonous, but by no means so much so as arsenic (242).

It is found in Sicily, Hungary, and various parts of Germany: and is
very common in several districts of China.

245. _ANTIMONY is a compact metallic substance of brilliant and slightly
bluish white colour, destitute of ductility, and about seven times
heavier than water._

_Its texture is laminated, the plates crossing each other in almost
every different direction. It is as hard as silver, and so brittle that
it may easily be reduced to powder, in a mortar._

In the state of the Connecticut, North America, it is said that
antimony, in a pure metallic form, is found in such abundance that, in
some places, large masses of it may be seen lying on the surface of the
ground. The principal supply of antimony in Europe is from an ore which
is found in Hungary and Norway, called _sulphuret of antimony_. The
process of bringing it into a state for use is very simple. The mineral
is put into pots, each of which has a hole in the bottom, and which is
placed on another pot bedded in the earth. The upper pots, which are
filled with the mineral, are heated. As soon as the antimony is fused it
flows into the lower pots, while the substances with which it was
combined remain in the upper ones. The antimony fixes, and forms cakes
of the shape of the pots which receive it. In this state the metal
presents, in its fracture, a surface thick─set, with long needle─shaped
crystals, which, lying by the side of each other, compose, as it were,
the whole of the mass. It is afterwards re─melted and cast into cakes
for sale.

This metal, in a pure state, or alloyed only with a very small portion
of silver and iron, is found in veins of mountains in some parts of
France and Sweden, occurring in massive and kidney─shaped lumps of white
colour.

The only mine of antimony in Britain, which is of any importance, is at
Glendinning in Dumfries─shire. It was discovered in 1760, in searching
for lead ore, but was not regularly worked till 1763. In the first five
years about a hundred tons’ weight of antimony were obtained from it.
This at 84_l._ per ton, produced the sum of 8400_l._ The undertaking was
afterwards relinquished, but, as the price of antimony is now at least
thrice what it then was, it is supposed that this work, if resumed,
might prove an advantageous speculation. The vein of ore is only from
eight inches to a foot and a half in thickness.

Antimony was known to the ancients. The earliest account we have of it
is in the Sacred Writings. The passage in the Second Book of Kings,[4]
which states that, on the approach of Jehu to the city of Jezreel,
“Jezebel painted her face,” implies, in the original, that she stained
her eyes and eyebrows with antimony, for the purpose of making them look
black and large, a custom which, at that period, was prevalent in
several of the Eastern countries. Antimony was likewise considered by
the ancients a remedy against inflammations of the eyes.

This metal is the basis of many of the officinal preparations which are
now in use; and it was the basis of many others which were formerly
used, but are now discontinued. No mineral substance has so much
attracted the attention, or so much divided the opinion of physicians,
as antimony. One party extolled it as an infallible specific for almost
every disease; whilst another described it as a virulent poison, which
ought to be expunged from the list of medicines. It was on this metal
that the alchemists of the middle ages principally founded their hope of
discovering the philosopher’s stone; and, by a kind of good fortune, of
which we can cite but few examples, it has happened that, in pursuing a
chimera, they hit upon a succession of important realities. To the
unremitted perseverance with which they tormented this metal, if we may
so express it, the art of healing has been most essentially indebted.

Footnote 4:

  Ch. ix. v. 30. See also Ezek. Ch. xxiii. v. 40.

The first rational account of the properties of antimony was given,
about the end of the seventeenth century, by a French chemist, whose
name was Lemeri. Its great importance in medicine will be seen by an
enumeration of some of the most valuable preparations of it which are
still in use.

_Antimonial Wine_ is prepared from antimony, in conjunction with white
Lisbon wine. It is employed as an emetic; but, if mixed with milk, this
quality is said to be completely destroyed, and it becomes narcotic.

_Emetic Tartar_, which is much more employed in this country than all
the other antimonial preparations put together, is formed from antimony
mixed with its own weight of tartar, and a certain proportion of water,
and afterwards boiled, filtered, and suffered to crystallize.

_Butter of Antimony_ is obtained from a combination of antimony with
corrosive sublimate. It is denominated by chemists muriat of antimony,
and is usually a thick fatty mass of greyish white colour.

_Glass of Antimony_ is a vitreous substance of reddish brown colour,
which is occasionally used in medicine, but more frequently in colouring
the imitations of yellow diamond, Oriental, Brazil, and Saxon topaz,
hyacinth, emerald, and beryl.

_James’s Powder_, or _Antimonial Powder_, is a well─known medicine,
composed of phosphat of lime and antimony.

An alloy consisting of sixteen parts of lead and one part of antimony
constitutes the metal of which _printers’ types_ are formed. This alloy
does not differ from lead except in being considerably harder and more
tenacious. The plates on which music is engraved are formed of a mixture
of tin and antimony; and the oxides of antimony are used for the
colouring of glass.

246. _BISMUTH is a reddish white semi─metal, harder than silver, and
composed of broad brilliant plates adhering together._

_It is nearly ten times heavier than water, and is so brittle as readily
to break under the hammer. None of the semi─metals are so easy to be
fused as this; it melts even in the flame of a wax candle, and long
before it becomes red hot, and has the singular property of expanding as
it cools._

The ores of bismuth chiefly occur in Sweden, Norway, Germany, France,
and England. This metal appears to have been known to the ancients. It
was confounded by them with tin; and, even in our own manufactories, it
is known to the workmen by the name of _tin─glass_.

It is not of much use in the arts; but its fusibility renders the
working of it very simple and easy. It is employed in the composition of
some of the soft kinds of solder; and is also used for giving hardness
to tin and other metals. Amalgamated with mercury it renders that metal
less fluid; and the addition of it to mercury and tin is found useful in
the foliating or silvering of looking─glasses. Some manufacturers use it
in the composition of pewter; but it is said that this ought not to be
done, particularly for the formation of vessels intended to contain
food, as bismuth partakes of the noxious properties of lead, and
sometimes contains even arsenic. It is also occasionally employed in the
fabrication of printers’ types.

A very singular metal is formed by melting together eight parts of
bismuth, five of lead, and three of tin. Tea─spoons formed of this metal
surprise all who are unacquainted with their nature: they have somewhat
the appearance of common spoons, but they melt as soon as they are put
into boiling water.

Bismuth reduced to powder, mixed with the white of eggs and applied to
wood, gives it, when gradually dried and rubbed with a polisher, the
appearance of being silvered. If this metal be dissolved in aquafortis
(30), and water be poured into the solution, a white powder
precipitates, which is an oxide of bismuth, and which, after being well
washed, is used as a pigment, under the name of _pearl─white_. From its
beautiful appearance, this powder is sometimes employed by ladies for
painting their skin; a practice which cannot be too much condemned, both
on account of the danger with which it is attended, and from its soon
injuring both the texture and natural colour of the skin. It has the
further disadvantage of turning black when touched by the fumes of fetid
and other substances; and ladies, who have used this cosmetic, and have
afterwards bathed in the Harrowgate waters, have come from the bath a
perfectly tawny colour. It was probably the oxide of bismuth which the
Roman ladies used for whitening their skin; for Martial, in speaking of
a lady, who made too free an use of cosmetics, describes her as afraid
even of the sun. The oxide of bismuth is used in the composition of most
of the pomades employed in France for painting the face.

A preparation of bismuth has lately been employed in medicine, as a
remedy against spasmodic affections of the stomach.

The following is a pleasing experiment, illustrative of metallic
crystallization. Melt a ladleful of bismuth, and allow it to cool slowly
and quietly till a thin crust is formed on the surface: then, with a
pointed iron, make two small opposite apertures through the crust: and,
through one of these, quickly pour out the fluid portion, as carefully
and with as little motion of the mass as possible. The air having
entered by the other aperture, there will appear, on removing the upper
crust by means of a chisel, when the vessel has become cold, a
cup─shaped concavity, studded with very brilliant crystals, and more or
less regular according to the quantity of metal employed, the
tranquillity and slowness with which it has cooled, and the dexterity
with which the fluid portion of the mass was poured off before it became
solid. The same effect may be produced by melting bismuth in a crucible
which has a hole in the bottom, lightly closed by an iron rod or
stopper; this is to be drawn out when the mass begins to congeal. By so
doing, the upper portion, which is fluid, is made to run off, and a cake
studded with crystals will be left.


247. _COBALT is a semi─metal of grey colour with a shade of red,
brittle, somewhat harder than silver, nearly eight times as heavy as
water, is attracted by the magnet, and is itself capable of being
rendered permanently magnetical._

_The ores of cobalt are not numerous, and are, for the most part,
combinations of this substance with other metals, or of its oxides (24)
with arsenic, or with sulphuric acid (21)._

The name of this metal implies an evil being, (_Kobold_, German, goblin)
and is said to have been given on account of the vapour of arsenic,
which issues from it, tormenting the miners, and making them believe
that they are afflicted by wicked spirits. Hence it was once customary
in Germany to introduce into the church service a prayer that God would
preserve miners and their works from _cobalts_ and _spirits_.

Cobalt is found in several parts of Europe, but most plentifully in the
southern borders of France, and in Saxony; and the cobalt ores of Hesse,
although they were formerly used for no other purpose than the mending
of roads, are said now to yield a clear profit of nearly 15,000_l._ a
year. Some parts of our own country yield this substance in considerable
abundance, particularly the Mendip Hills in Somersetshire, and a mine
near Penzance in Cornwall.

After the ore is taken from the earth, it is broken into pieces about
the size of a hen’s egg, and the stony parts are picked out. The sorted
mineral is then pounded in mills, and sifted through brass─wire sieves.
The lighter particles are next carried off by water. After undergoing
some other preparations, to rid it of the impurities and foreign matters
with which it is connected, it appears in the form of a dark grey oxide.
The working of the cobalt ores in Germany is considered so injurious, on
account of the arsenic with which they are combined, that much of the
labour is performed by criminals who are condemned to it for the
commission of crimes which, by the laws of the country, have deserved
the punishment of death.

As a metal, cobalt was unknown till the year 1733, when it was
discovered by a celebrated Swedish chemist whose name was Brant. In its
metallic state it is not employed in the useful arts; but in a state of
oxide it is found extremely valuable in the colouring of porcelain, in
painting, enamelling, and for other purposes. Cobalt and ultramarine
form the most permanent blue colours with which we are acquainted. The
old painters generally used them for the representation of the sky and
of blue drapery, and this is the reason why these parts in some old
pictures have been found so much more durable than any others.

_Zaffre_ is an oxide of cobalt mixed with about three times its own
weight of calcined and pounded flint. It has been chiefly imported into
this country from Saxony and Bohemia, but it is now also manufactured
from cobalt dug from mines in the Mendip Hills and in Cornwall. In
Staffordshire there are several persons who carry on a considerable
trade in preparing this colour for the earthenware manufacturers of that
county.

This substance is extremely valuable for the colouring of porcelain and
glass; as it resists without change, the effects of the most intense
heat. Hence also it is advantageously used for giving various shades of
blue to enamels, and to glass manufactured in imitation of lapis lazuli,
turquoise, sapphire, and various precious stones. So intense is the
colour imparted by it that a single grain of zaffre will give a full
blue tint to 240 grains of glass.

_Smalt_ is a kind of glass, of dark blue colour, formed by melting
zaffre with three parts of sand and one of potash; when this substance
is ground to a coarse powder, it has the name of _strewing─smalt_, and
is much used by sign painters, as an ornamental filling up of the vacant
space betwixt the letters of signs. In Germany it is frequently employed
instead of sand for the purpose of drying ink after writing. The same
substance reduced to a perfectly fine or impalpable powder, is the
article which is sold under the name of _powder─blue_, and which is not
only used by laundresses and others in the getting up of linen, but also
as the basis of several kinds of paint; and by the manufacturers of
writing and printing papers, to give a blue tinge to those articles.

A solution of the oxide of cobalt in spirit of salt (muriatic acid, 29)
and afterwards diluted till nearly the whole of its colour disappears,
forms one of the most beautiful _sympathetic inks_ with which we are
acquainted. If a landscape be drawn with Indian ink, and, afterwards,
the foliage be washed over with this solution, it will have no peculiar
appearance; but, on holding the paper near the fire, the part
representing the vegetation will gradually assume a green tint, which
will subside on removing the paper into a cool situation.


248. _MANGANESE, in the state that we usually see it, is a black oxide
of a metal which is of a silvery grey colour, of leafy or foliated
texture, and somewhat more than six times as heavy as water._

Mines of manganese have long been worked in several parts of Great
Britain, but particularly in the counties of Devon and Somerset. Near
Exeter and in the Mendip Hills this mineral is found in great abundance.

It is employed for various useful purposes. In the manufacture of the
finer kinds of glass it is used in a double capacity, both as a
colouring material and as a destroyer of colour. As a colouring
ingredient, the imitators of several precious stones are indebted to it
for the red and purple tints which they give to the oriental ruby, the
balais ruby, and the amethyst.

The violet colour given to porcelain is obtained from manganese. This
substance is also used for the glazing of black earthen ware, as a
paint, and an ingredient in printers’ ink. As a discharger of colour it
is applied in small quantities, and, by the oxygen which it gives out,
it is said completely to destroy any tinge left in the glass, by the
presence of iron, and some other colouring matters. This property has
obtained for it the appellation of the _soap of glass_.

It is from manganese that all the oxygen gas (21) used by chemists is
obtained. By the application of a red heat this is yielded in such
abundance that an ounce of the oxide of this metal will yield about two
quarts of gas. The consumption of manganese has, of late years, become
very considerable by the discovery of the oxygenated muriatic acid,
which is now extensively used in the bleaching of linen and cotton; that
liquor being made by the distillation of the oxide of manganese with
spirit of salt (muriatic acid, 29).


────────────────────────────────────────────────────────────────────────




                           COMPOUND MINERALS,


                                   OR

                                 ROCKS.

                                ───────


249. There exist considerable masses of minerals in a state of
combination, or aggregation with each other. These constitute the rocks
and soil of which the globe of the earth is composed; and the study of
them is called GEOLOGY. The opinions of learned men relative to their
structure, and original formation, have produced various systems
denominated _theories of the earth_; but, when we consider that the
greatest depth beneath the surface to which the art and industry of man
have been able to penetrate, does not exceed 1/35000 part of the earth’s
diameter, we must confess that this is very insufficient to allow of any
correct opinion being thereby formed concerning the structure of the
whole.

Modern geologists, for the more convenient arrangement of the compound
minerals, have divided them into four classes, which they denominate
_primitive rocks_, _secondary rocks_, _alluvial depositions_, and
_volcanic rocks_.


                          I. PRIMITIVE ROCKS.

250. _These are so called from their being considered by geologists, to
belong to the first formed parts of the globe._

Rocks of this description are of a nature extremely hard. They contain
no vestiges whatever of animal or organic remains; and the substances of
which they are composed are crystallized. They rise through other rocks
at various elevations, in every quarter of the globe; and never either
alternate with, or rest upon rocks that enclose organic remains, though
they are themselves frequently covered by such.

The following are the principal kinds.

251. _GRANITE or moonstone is a compound rock composed of felspar (110),
quartz (76), and mica (123), each in crystalline grains of various size,
and promiscuously arranged; sometimes one and sometimes the other of
these ingredients predominates, but generally the felspar._

This is one of the most common and most widely extended rocks that are
known; and is considered as the foundation on which the secondary rocks
are deposited. In Cornwall it is very abundant, and veins both of copper
and tin are found in it. Granite forms the summits of the highest
mountains in Scotland, of the highest of the Grampian Hills, the Alps,
and the Pyrenees; and indeed the loftiest parts of most of the countries
of the world. The Logan or rocking stones, in Cornwall, are immense
blocks of granite.

The uses of this stone are numerous and important. Millstones, steps,
troughs for stamping mills, and innumerable other articles, are made of
it. The streets of London are chiefly paved with granite, and its
hardness and durability render it peculiarly eligible for this use.
Weather has little effect upon it. Consequently, when applied to
architectural purposes it is found infinitely preferable to Portland
stone, of which nearly all the public buildings of modern date in London
have been constructed, and many of which are fast going to decay. This
circumstance induced the proprietors of the Waterloo Bridge to adopt
granite in the construction of that edifice. Mr. Smeaton also chose it
for the outer walls of the Eddystone Lighthouse.

252. SCOTTISH GRANITE.—Scotland is remarkable for many kinds of granite,
some of which are susceptible of an excellent polish. The greatest part
of the mountain of Ben Nevis, near Fort William, is composed of a
reddish granite, one of the best and most beautiful that is known. This
mountain is nearly a mile in perpendicular height, and is said to
contain granite enough for all the kingdoms of the earth, although they
should be as partial to this stone as the ancient Egyptians were.
Columns and obelisks of any size and height might be cut from it: for
the rock is one uniform mass, without appearance of strata, division, or
fissure of any kind. A convincing proof has been given of the strength
and hardness of this granite, in a fragment of several tons’ weight,
which fell from nearly the top of a precipice five hundred yards in
height, upon a hard and solid rock below, and yet continued entire.

253. GRANITE OF INGRIA.—A beautiful red granite is found in some parts
of Russia, remarkable on account of the felspar (110) that it contains,
appearing in round or oval pieces, from half an inch to two inches in
diameter. This granite, when polished, exhibits shining spots of round
or oval shape, which give to it somewhat the appearance of being studded
with precious stones.

The royal summer garden at Petersburg is decorated with a superb
colonnade of Ingrian granite. The columns are sixty in number, and each
of a single piece twenty feet high, and three feet in diameter. Many of
the public buildings in Petersburg are of this granite. An immense block
of it thirty─two feet long, twenty─one feet broad, and seventeen feet
high, forms the pedestal of the celebrated equestrian statue of Peter
the Great, in that city.

254. GRAPHIC GRANITE.—A singular kind of granite has been discovered in
the island of Corsica, and lately near Portsoy in the north of Scotland.
The ground of this granite is a whitish or reddish yellow felspar, in
which are embedded crystals of quartz each from an inch to an inch and
half long, and several lines in diameter. The name of graphic granite
was given to it in consequence of an imaginary resemblance which the
sections of these crystals have to Hebrew, or Arabic, and sometimes to
musical characters.

255. _GNEISS is a primitive rock, consisting, like granite, of felspar
(110), quartz (76), and mica (123), but differing from that rock in its
structure, being slaty._

Mountains of gneiss are not so steep as those of granite, and their
summits are usually rounded. Ben Lomond and others in Scotland, and
mount Rosa in Italy, are almost wholly of gneiss, as well as the middle
part of the Pyrenees. It is not an uncommon rock, but in Britain is of
less frequent occurrence than granite.

Many valuable metallic ores are found in veins of gneiss. This rock also
sometimes contains crystals of garnet (70), and tourmaline (69).

256. _MICA SLATE, or MICACEOUS SCHISTUS, is a primitive rock of slaty
structure, consisting principally of quartz (76) and mica (123)._

Like gneiss, it is rich in ores. It often contains beds of magnetic
ironstone (235), galena (239), copper, blende (241), cinnabar (228), and
sometimes even gold. It frequently has garnets, and sometimes
tourmalines (69), interspersed in different parts of it.

Mica slate occurs in many parts of Scotland; the mountain of
Schehallien, and the rocky adjacent country, are in a great degree
composed of it.

257. _CLAY SLATE is a primitive rock generally of dull blue colour, more
or less compact, always slaty, and always stratified._

Under the appellation of clay slate are included _roofing slate_ (120),
_whet slate_ (122), _drawing slate_ (121), and some other kinds already
described.

Few rocks abound more in veins and beds of valuable metals than slate.
In different countries it contains ores of tin, lead, cobalt (247),
silver, and copper; and gold, and mercury (228) sometimes occur in it.
The celebrated quicksilver mines of Idria (228), and the immense mass of
copper at Parys mountain in the island of Anglesea (230), are in clay
slate. Crystals of pyrites (236), and sometimes garnets (70), and thin
layers of quartz (76), and felspar (110), are all occasionally found
embedded in it.

This is a widely─extended rock; it sometimes forms whole mountains, and
even chains of mountains; but these usually have a gentle acclivity. The
summit of the celebrated mountain called Skiddaw in Cumberland is of
clay slate.

258. _PRIMITIVE LIMESTONE is a simple mountain rock of crystalline or
granular structure; and generally of white, yellowish, greenish, or
reddish colour._

To this species of rock belong many of the rich and beautiful kinds of
marble already described (143, &c.). Carrara, or statuary marble (146),
is a familiar instance of it. Whole mountains in Stiria, Carinthia,
Carniola, and the Pyrenees, and three mountains in Switzerland, 10,000
feet in height, are of primitive limestone. The mountain of Filabres in
Spain, is said to consist of one block of white granular marble, 2,000
feet high, and three miles in circuit; without intermixture of other
earths or stones, and almost without a fissure.

Various mineral ores, in beds and veins, as lead, zinc (241), and iron,
are occasionally found in this kind of rock.

259. _PRIMITIVE TRAP is a mountain rock composed of a black mineral
called hornblende, mixed, in some varieties, with felspar (110), and, in
others, with mica (123)._

The word _trap_ is of German origin, signifying a _stair_; and rocks of
this formation are called trap rocks, because their strata, when
exposed, usually jut out, one beneath the other, somewhat like a stair.
Under this term is comprehended a series of rocks, distinguished chiefly
by the hornblende, which they all contain.

Rocks belonging to this formation are numerous. They occur in Scotland;
and abundantly in Derbyshire and some other parts of England. In many
countries they constitute considerable hills. They abound in ores.

260. _SERPENTINE is a primitive rock, usually consisting of quartz (76),
magnesia (198), alumine (197), with a portion of oxide (21) of iron._

This rock and its various uses, have been already described (132). It
generally occurs in shapeless masses and beds; and seldom in distinct
strata. It is found in Cornwall, the island of Anglesea, and several
parts of Scotland; but it rarely forms mountains.

Ores of lead, silver, and copper, are sometimes found in serpentine.

261. _PORPHYRY is a primitive rock, consisting of quartz (76) or felspar
(110), or both, embedded in a solid and compact cement or ground._

_The ground or basis of porphyry varies in the different kinds. In some
it is claystone, in others pitchstone, hornstone, or compact felspar._

When not covered by other formations, porphyry sometimes forms single
rocks; but it never constitutes elevated mountains. It occurs in beds of
considerable magnitude, but never appears in distinct and well─defined
strata.

There are many beautiful and splendid works in porphyry. Obelisks,
statues, and columns, wrought in it, have had great celebrity. It is
susceptible of a polish as high as that of marble, but is so hard, that
the expense of working it has caused it to be much neglected by the
moderns. This hardness, however, renders it very durable, and also
constitutes it a material of great utility for mortars, slabs for
grinding colours upon, and for several other purposes.

Porphyry was much esteemed by the ancient Egyptians; and Pliny informs
us that the procurator─general in Egypt, under Claudius Cæsar, brought
thence, for that Emperor, certain statues of porphyry, which he
conceived to be very valuable: this act, however, was not much approved,
and the example was not followed by any other Roman.

The principal quarries of porphyry are in Egypt; but this stone is also
found in Italy, Germany, and various parts of the European continent. It
may be traced from Norway to the borders of the Black Sea, and it has
been discovered in some of the western and northern parts of Great
Britain.

262. _SIENITE is a rock composed chiefly of felspar (110) and
hornblende. Its colours are usually reddish and black._

_Some varieties of it contain quartz (76) and mica (123), with but
little hornblende. In these the colours are various._

Although this is a less abundant rock than any of those that have yet
been mentioned, it occurs, in great abundance, at Mount Mado, in the
island of Jersey. There are extensive quarries of it in that mountain,
not only for the use of the island, but for exportation to England, and
other distant countries. The cliffs, for a long space, and an elevation
of a hundred feet or more, consist entirely of sienite, in large masses,
which are apparently uninterrupted by a single fissure. Shafts for
columns of considerable length have been taken from these quarries; and,
were the demand sufficient to call for new openings, it is imagined that
columns of twenty feet and upwards in length might be raised. The
felspar is of a flesh colour, and the stone is capable of a beautiful
polish.

A somewhat similar kind of sienite is found at Grande Roque, in the
island of Guernsey, in large masses, which are quarried for building
stones. Sienite also occurs in some parts of Scotland and Derbyshire; in
Saxony, Hungary, the island of Cyprus, and Egypt. Its name has been
derived from that of the city of Syene, in Upper Egypt, where it is
found in great abundance.

Sienite was much used by the ancients in ornamental architecture. What
was called the red granite of Egypt (for this rock has usually been
considered a granite) furnished numerous magnificent obelisks and
columns, of a single piece, which have been much admired in Rome and
other places. The ancient artists sometimes cut this kind of stone into
statues, vases, monumental and other works. The celebrated column in
Egypt, upwards of ninety feet high, and known by the name of Pompey’s
Pillar, is formed of sienite.

In veins of this rock are found, in different countries, many kinds of
metallic ores: among others, silver, iron, tin, copper, and lead.

263. _QUARTZ ROCK is a simple mountain rock, usually of granular
texture, and whitish colour._

_It sometimes contains mica, in which case it has a slaty form._

In certain mountains of Scotland, and the Scottish islands, quartz rock
is very abundant. On the Continent it appears in Saxony, Bohemia,
Silesia, and several other countries. We are informed that a mountain,
350 feet high, and near 5000 feet broad and long, one of the Altaisch
chain, in Siberia, consists entirely of a milk─white quartz.

The uses of quartz have been already described (76, &c.) This kind of
rock does not contain metallic ores of any description.

                          II. SECONDARY ROCKS.

264. SECONDARY ROCKS _are composed of, or at least contain within them,
the mineralized remains of organic substances_. These must necessarily
have been formed at a period subsequent to the formation of those
organized bodies the remains of which they enclose; and they have
apparently been formed by the deposition of water. Hence it is that, to
distinguish them from rocks of the preceding class, they have received
the appellation of secondary. They always rest upon or cover primitive
mountains, and sometimes lean upon their sides or invest them.

Werner, the celebrated German mineralogist, makes two divisions of
secondary rocks. The first of these he denominates _transition rocks_,
and states that they are less perfectly crystallized than the primitive
rocks; and that they enclose the remains of marine animals, no species
of which are at this time known to exist: the other division he terms
_floetz_, or _flat rocks_, because they are generally disposed in
horizontal or flat strata. Some of the latter contain the fossil remains
of marine animals and shells, approaching in character and appearance to
the kinds which are now found in the ocean; and others contain shells
precisely similar to those now known to exist. These rocks usually occur
at the foot of primitive mountains, or in deep valleys.


                          1. TRANSITION ROCKS.

265. _TRANSITION LIMESTONE is distinguished by containing marine
petrifactions of corals, and other zoophytes which are supposed no
longer to exist. It often contains veins of calcareous spar, and
exhibits a variety of colours, which give to it a marbled appearance._

This species of limestone occurs in immense beds, and forms a great
portion of the mountainous parts of Derbyshire and Scotland; but it does
not rise so high, on the sides of mountains, as primitive rocks (250).

It often contains veins of valuable metallic ores. When cut and
polished, many of the varieties of transition limestone are beautiful
marbles; some of them have been already described.

266. _GREY WACKA is a transition rock, composed of pieces of quartz
(76), flinty slate, felspar (110), and clay slate (120), cemented
together by a basis of clay slate._

_It has various appearances, the pieces being sometimes as large as a
hen’s egg, and sometimes so small that they can scarcely be perceived by
the naked eye._

When the rocks of grey wacka are not covered by those of any other
formation, they form round─backed hills, usually insulated towards the
tops, and intersected by deep valleys. They are widely distributed: and
are often extremely rich in ores, both in beds and veins. Almost all the
mines of copper, lead, and zinc, in the Hartz, are in grey wacka; and,
in Transylvania, this species of rock is traversed by numerous small
veins of gold.


                       2. FLOETZ, OR FLAT ROCKS.

267. _OLD RED SANDSTONE, or MILLSTONE GRIT, is a floetz or flat rock,
composed of large grains of sand or quartz (76), coloured by oxide (21)
of iron, and usually cemented together by a kind of clay._

In several parts of Derbyshire this kind of rock forms the uppermost
stratum; and in some places, is known to be 120 yards thick.

What are known by the name of _peak millstones_ are formed of millstone
grit. They are chiefly obtained from quarries near Nether Padley, in
Hathersede, Derbyshire; a very inaccessible part of the country, but
where the stone is of better quality than it can elsewhere be procured.
These millstones are made of different dimensions, from two feet in
diameter, and eight inches thick, to five feet and half in diameter, and
seventeen inches thick.

Some of the beds of millstone grit, which have spherical stains in them,
of light red colour, are said to be infusible; and are consequently a
valuable stone for lining the hearths of iron and other furnaces, where
an intense heat is required. These are called _firestones_, and Roches
quarry, near Upper Town, in Ashover, Derbyshire, is famous for them.

The upper beds of this kind of rock are often thin, and capable of
division, so as to make excellent _paving stones_, or _flags_. There is
a particular bed of it at Stanton, in the Peak of Derbyshire, so porous
that it is made into _filtering stones_ for the cleansing of turbid
water.

268. _THIRD SANDSTONE, GRITSTONE, or FREESTONE, is another kind of
floetz or flat rock, formed of very small agglutinated particles of
sand. It is opaque, usually of whitish colour, and found in large
masses, of various degrees of hardness._

The name of _freestone_ has been given to this kind of rock, from its
capability of being broken or hewn, with nearly equal facility, in any
direction. Hence, as well as from its great durability, it is peculiarly
esteemed for buildings. It is also formed into cisterns and troughs of
various kinds; into pillars for supporting corn ricks; into _rolling
stones_; and into _grinding stones_ for cutlers, edge─tool makers, and
workers in polished steel. _Paviors’ flags_, or the stones used for the
paving of footpaths, yards, kitchens, and out─houses, are generally flat
pieces of freestone.

_Scythestones_, or stones for the sharpening of scythes upon, are made
of freestone. Considerable numbers of these are wrought in Derbyshire;
and the dexterity that is displayed in cleaving and forming them is
somewhat remarkable. The workmen use sharp─pointed picks, several very
small wedges, and a hammer. A proper block of stone being selected, two
or three of these small wedges are set in a row, by gentle blows of the
hammer. These blows are successively repeated till the stone splits. The
wedges are then set in a straight line into the face of the piece split
off, and the stone is cleft again in that direction. In this manner the
sub─divisions are continued, until a piece remains of size to make two
scythestones, each an inch and a half square, and about twelve inches
long. This the workman holds in his left hand, nearly upright; with the
point of his pick he traces a deep nick down the middle of first one
side and then the other; and then by a slight blow of his pick he
separates it, into two, so dexterously, that not more than three or four
in a hundred are broken in the cleaving. Such stones as are intended for
round rubbers, are first reduced into an octagonal shape by the point of
the pick, and then handed over to women and boys, who grind or rub them
in a notch formed in a hard stone, until they are of the requisite
shape. The square ones are finished by being ground on a flat stone.

                  *       *       *       *       *

Other rocks, belonging to what is called the floetz, or flat formation,
have been already mentioned, under the heads of _lime─stone_ (140),
_gypsum_ (192), _rock salt_ (202), _chalk_ (141), and _coal_ (217).


                       III. ALLUVIAL DEPOSITIONS.

269. _These are described to comprehend all such substances as have been
formed from previously existing rocks, of which the materials have been
worn down, by long exposure to the agency of water and air, and
afterwards deposited in nearly horizontal beds on the surface of the
land._ Alluvial deposits have been formed, and are still forming in
every quarter of the globe. They occur both in mountainous regions and
in flat countries, filling up the valleys or hollows in the one; and
often forming vast and extended plains in the other.

They consist of _peat_, _sand_, _gravel_, _loam_, _clay_, and other
substances.

IV. VOLCANIC ROCKS.

270. _Volcanic rocks are composed of such mineral substances as have
been ejected from volcanoes, or have been formed by the agency of
subterraneous fires, and have undergone certain changes in such fires._

They are of two kinds; the one called _pseudo volcanic_, such as burnt
clay, porcelain jasper, and earth─slag, which have been altered in
consequence of the burning of beds of coal in their neighbourhood; and
the other, called _true volcanic_ minerals, such as stones, ashes, and
lava, which have been thrown out of real volcanoes.

271. It will somewhat tend to illustrate the history of the mineral
kingdom, to state, in conclusion, under a tabular form, the relative
heights of the principal mountains, or masses of rocks, which occur in
the different countries of the world; previously remarking, that the
most lofty and magnificent of these, respecting which any account
sufficiently authentic has hitherto been obtained, are the mountains of
Nepaul and Thibet, in Asia, one of the former being 27,667, and the
highest of the latter measuring at least 23,262 feet, or from 4½ miles
to 5¼ miles in perpendicular height above the level of the sea.
Previously to the knowledge that has lately been attained respecting the
Asiatic mountains, those of the Andes, on the continent of South
America, had been considered by far the highest in the world. One of
them, Chimborazo, is 20,900 feet in height. Of the European mountains,
the highest is Mont Blanc, in Switzerland, which measures 15,680 feet,
or about 2¾ miles. The loftiest summit within the British islands is Ben
Nevis, in Inverness─shire, Scotland, which does not exceed 4,380 feet,
or somewhat more than three quarters of a mile; and the great pyramid of
Egypt, the loftiest work of human art and industry with which we are
acquainted, and which will serve as a point in the scale, measures only
477 feet.

272. It has been remarked that the greatest altitude at which _bananas_
and other _palm─trees_ grow in America is about 3280 feet above the
level of the sea (Frontispiece, Fig. 48): that in the torrid zone, the
superior limits of _oaks_ is about 10,500 feet (49), of _pines_ 12,000
feet (50), and of _lichen plants_ 18,225 feet (51). The American
travellers, Messrs. Humboldt and Bonpland, on the twenty─third of June,
1802, ascended the mountain of Chimborazo to the height of 19,400 feet
(52). The highest flight that has been remarked of the South American
vulture, called the _condor_, was 21,000 feet (53). M. Lussac, on the
16th of September, 1804, ascended in a balloon from Paris, to the height
of 22,900 feet. In Switzerland, the limit of perpetual snow is above the
altitude of 9000 feet (54).


                  =Height of the Principle Mountains.=

                                                        _Frontispiece._

                                                                Ft.
                                                              above

                                                        Fig. the sea

=_British Islands._=

              Scotland Ben Nevis, Inverness─shire       1    4380
                       Ben Lawers, Perthshire           2    4051
               England Skiddaw, Cumberland              3    3530
                       Cross Fell, Cumberland           4    3390
                       Helvellyn, Cumberland            5    3324
                       Wharnside, Yorkshire             6    2480
                       Ingleborough, Yorkshire          7    2380
                 Wales Snowdon, Caernarvonshire         8    3568
                       Cader Idris, Merionethshire      9    3550
               Ireland Macgillicuddy’s Reeks, Kerry    10    3404
                       Sleibh─Dorin, Londonderry       11    3150

=_Continent of Europe._=

                France Mont d’Or, Auvergne             12    6707

                       Puy de Sausi, Auvergne          13    6700

              Pyrenees Mont Perdu, the highest of the  14  11,283
                       Pyrenees

                       Le Pic Blanc, Spain             15  10,205

                  Alps Loucira                         16  14,451

                       Loupilon                        17  14,144

           Switzerland Mont Blanc, highest mountain    18  15,680
                       in Europe

                       Mont Rosa                       19  15,555

                       Mont St. Gothard                20  10,014

                 Italy Mont Cimone                     21    6401

                       Vesuvius                        22    3900

               Germany Ortler─Spitze, Tyrol            23  15,430

                       Ostelle, Saltzburg              24  12,800

                       Carpathian Mountains, highest   25    8640
                       summit

                       Lomnitz Peak                    26    8640

                Sweden Areskutan, Jempland             27    6180

=_Islands._=

             Teneriffe Peak of Teneriffe               28  12,236
                Sicily Ætna                            29  10,963
               Jamaica Blue Mountains                  30    7431
               Iceland Snæfiel                         31    6860
                       Hecla                           32    4900

=_Asia._=

                 India Dhawalgeri in Nepaul            46  27,667
                       Mountains of Thibet             47  23,262
                Turkey Mount Lebanon, estimated at     33    9520
               in Asia Mount Ararat, estimated at      34    9500
                       Mount Ida                       35    4960

=_America._=

          Andes, South Chimborazo, Quito               36  20,900
              America. Cotopaxi, Quito                 37  18,880


               =Height of Remarkable Lakes, Cities, &c.=

                  Alps Lake of Lausanne                38    8640

                       Lake of Lanzon, on the          39    6797
                       mountain of Olan

           Switzerland Lake of Lucerne                 40    1408

         South America City of Riobamba, Quito         41  18,800

                       City of Quito                   42    9356

         North America City of Mexico                  43    7424

               Austria Town of Eisenerz                44    2056

                 Egypt The great Pyramid               45     477


────────────────────────────────────────────────────────────────────────




                           WATER IN GENERAL.

                                ───────


273. WATER, generally speaking, is a transparent and nearly
incompressible fluid, the component parts of which are two kinds of gas,
called hydrogen (45) and oxygen (21).

It is _liquid_ in the common temperature of our atmosphere, assumes a
solid state under the denomination of _ice_, in a cold temperature (32°
of Fahrenheit’s thermometer); and, by heat at 212°, is converted into an
elastic vapour of almost incredible force, called _steam_. At any
temperature betwixt these two points, it returns, unaltered, to its
liquid state. The weight of water is about 816 times greater than that
of atmospheric air.

Water abounds in, and may be considered as, a kind of general cement to
all solid bodies. It performs the most important functions both in the
animal and vegetable kingdoms, and even enters largely into their
composition.

A chief part of the nutrition of vegetables is the water which they
absorb from the earth through the pores of their roots. The great
quantity so absorbed may readily be imagined, when it is stated that the
driest and most compact kinds of wood, such as even heart of oak, when
converted into charcoal, lose, during the process, full three─fourths of
their weight; and that the fluid which escapes is nearly pure water.
This fluid is found in the driest of solid bodies, whatever be their
description. A piece of hartshorn kept for forty years, and thereby
become as hard and dry as metal (so that if struck against a flint it
would give sparks of fire), upon being distilled, was found to yield an
eighth part of its weight of water.

Every being with life, in a great degree, lives by it; and whatever
grows, through it receives its growth; and wherever it enters, it
promotes and sustains life, preserving the whole of created nature in
their proper classes of existence. And whether we consider it as
productive of health to animals and vegetables, as requisite to the
existence and beauty of the earth, or as one of the great powers by
which the Almighty works in the support of the world, we cannot but
admire and adore the wisdom by which it has been ordained.

In the various kinds of water, even of that which is commonly used in
drinking, and for the preparation of food, there is great difference
both of taste and appearance. This difference is chiefly occasioned by
the foreign matters which they hold in solution or suspension. In some
cases the quantity of these is so minute as to have but little influence
on the taste; but in others they alter its properties altogether, and
render the water noxious, or medicinal, or unfit for the preparation of
food.

The _chemical analysis of water_, for the purpose of ascertaining the
different substances which it holds in solution, is one of the most
difficult and complicated operations that is known in this branch of
science; and one that exercises, in a peculiar degree, both the skill
and industry of the operator. The difficulty arises not only from the
diversity of the bodies which occur, but from the very minute quantities
of some of them.

These bodies are discovered by an addition to the water of certain
substances, the consequence of which is some change in its appearance,
and this change indicates the presence or absence of the bodies
suspected.

The substances thus employed are very numerous, and have the name of
_tests_. The methods of ascertaining the exact proportion of each of
these ingredients are much too complicated to require a place in the
present work.

Water cannot be obtained in any state of perfect purity except by the
artificial process of distillation.


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                         ORDER I.—COMMON WATER.


274. _RAIN WATER is considered to be next in purity to distilled water,
from its having undergone a natural distillation. Its foreign contents
vary according to the state of the air through which it falls. Hence,
for instance, when it passes through the atmosphere of a smoky town, it
becomes impure: and when collected in towns, it frequently acquires a
small quantity of sulphat of lime (192), and calcareous matter from the
mortar and plaster of the houses._

This water is always very soft; and is, consequently, well calculated
for the dissolving of soap, in washing and other processes. It is also
peculiarly adapted to the solution of alimentary or colouring matter, in
the preparation of food and dyeing, and is accordingly used to great
extent for these purposes. By the addition of a small quantity of a
solution of barytes (195), it may be rendered sufficiently pure for all
chemical uses.

If rain water be long kept, especially in hot climates, it acquires a
disagreeable smell, and becomes putrid, and full of animalculæ.

275. _ICE and SNOW WATER are equal to rain water in purity; and the air
having been expelled from them during the process of freezing, they are
consequently devoid of air when first melted._

Ice and snow, in their natural state, are highly important to mankind.
It is a general law of nature that all bodies become more dense and
heavy by exposure to cold; but the freezing of water is an exception to
this law, and for a purpose of extreme benefit to mankind. By this
ordination it is that ice always rises to the surface of the water, and
thus preserves from the effects of the surrounding cold, a vast body of
heat in the fluid beneath; and is itself ready to receive its own
accustomed quantity upon the first change of the atmosphere. The
expansion of water, in freezing, is owing to its assuming a crystallized
form; and this expansion is often so great that glass bottles, filled
with water, are burst by it.

During the intense cold of winter, snow, which is of a soft and spongy
texture, is considered of great utility in preventing the immediate
access of the atmospheric air to the ground; it has doubtless been
designed by Providence as a garment to protect the incipient vegetation,
at that inclement season, from injury.

The inhabitants of all the extreme northern parts of the world use
thawed snow for their constant beverage during winter; and the vast
masses of ice which float in the polar seas afford an abundant supply of
fresh water to the navigators of those dreary regions. Snow water has,
however, long lain under the imputation of occasioning those
extraordinary swellings in the neck, which deform the inhabitants of
some of the alpine valleys of Switzerland; but this opinion is not
supported by any well─authenticated facts. Indeed it is rendered quite
improbable by the frequency of this disease in the island of Sumatra,
where ice and snow are never seen: and by its being quite unknown in
Chili and Thibet, though the rivers of these countries are chiefly
supplied by the melting of the snows.

276. _SPRING WATER is nothing more than rain water, which having
gradually filtered through the earth, collects at the bottom of
declivities, and there makes its way to the surface._

_It is obvious that spring water must be nearly as various in its
contents as the substances through which it flows._

Ordinary springs pass insensibly into mineral springs, according as
their foreign contents become more abundant; but it has not unfrequently
happened that waters have acquired great medical reputation from their
purity only. Although by far the greater number of springs are cold,
some are hot, or at least are of a temperature which, at all times,
exceeds that of summer heat: and this warmth is so little influenced by
the state of the atmosphere, that it is nearly the same both in summer
and winter.

The water of almost every spring is of such nature that it will not
dissolve, but curdles, soap; and cannot be used for dressing several
kinds of food. Water of this description is denominated _hard_, a
property owing to the great proportion of earthy salts which it holds in
solution, and which, at the same time, are not in such abundance as to
impair its taste. The most common of these salts is selenite, or sulphat
of lime (192), and chalk, or carbonat of lime (140); when it contains
only the latter, the water is easily rendered soft by boiling, which
expels the excess of carbonic acid (26), and thus causes the chalk to be
precipitated. Hence originates the earthy crust or _fur_ in such tea
kettles as have had hard water several times boiled in them.

The water of deep wells is for the most part much harder than that of
springs which overflow their channels.

277. _RIVER WATER is a mixture of spring and rain water, which, from
much agitation, and by long exposure to the air, in the course of its
channel, becomes, in general, tolerably soft and free from earthy
salts._

For washing, and other purposes of domestic economy, river water, from
its softness and purity, is not only preferable to spring water, but
also serves for many uses to which the latter cannot be at all applied.
As a beverage, however, it is in general vapid and unpleasant.

The waters of some rivers, particularly where the beds, over which they
flow, are sandy or stony, are remarkably pure. This is the case with
several of those in Switzerland, Wales, Scotland, and the northern
counties of England. The river Seine has great repute in France on this
account: it has been found, on accurate examination, even more pure than
Bristol water.

That of the river Thames, impregnated as it would appear to be with
putrid remains, is soft and good, when taken up at low water; and, after
rest and filtration, is found to contain but a small portion of any
thing either noxious or unpleasant. It is preferred, by mariners, to
most other water for sea store; but it soon becomes putrid, and
undergoes a remarkable spontaneous change. When, after having been kept
a month or two, a cask is opened, a quantity of inflammable air escapes,
and the water is black and nauseous. If, in this state, it be racked off
into large earthen vessels (oil jars it is said are commonly used for
the purpose), and exposed to the air, it gradually deposits a portion of
black slimy mud, and becomes perfectly clear, sweet, and fit for use.

278. _STAGNANT WATER contains greater impurities than any other. In
ponds and marshes particularly, it is filled with the remains of animal
and vegetable matters, which are there undergoing a gradual
decomposition._

_The water of lakes is not, in general, so much contaminated as this;
but from the same cause, it frequently has a slimy appearance, a
brownish colour, and an unpleasant taste._

From the putrefying contents of stagnant water, nutriment is afforded to
various living plants and insects which there supply the place of those
that perish. Its taste is vapid, unpleasant, and wholly destitute of
that agreeable freshness which is found in spring water. It is, however,
generally soft, and, by filtration, it may be freed from many of its
impurities.

The air which issues from marshes and stagnant pools is extremely
noxious, and is the cause of agues and other distressing complaints, to
such persons as reside in the neighbourhood of them or are much exposed
to them; and the injurious effects of such air have also been considered
to extend to the internal use of these waters.


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                          ORDER II.—SEA WATER.


279. _SEA WATER is a very heterogeneous compound, not only containing a
considerable portion of saline substances, but holding also suspended in
it an infinite number of minute animal and vegetable particles, to the
gradual putrefaction of which its peculiarly nauseous and bitter taste,
at the surface, is in some measure to be attributed._

_The average quantity of salt in sea water is estimated to amount to
about one─thirtieth part of its weight. It likewise contains a certain
portion of muriat of magnesia, sulphat of magnesia or Epsom salts (199),
and a small quantity of sulphat of lime (192). Sea water, taken from a
great depth, has not the bitterness which the water of the surface has:
it is only saline._

No natural waters, if we except certain brine springs and salt lakes,
are so saline as those of the ocean; and the latter differ, in this
respect, in different parts of the world. At the tropic, the sea is in
general more salt than it is at the poles, a wise ordination to preserve
it, in those climates, from the great tendency to putrefaction: and, at
a considerable depth, it is always found more salt than at the surface.
The water of the Baltic is much less salt than that of the Atlantic; and
it is a remarkable circumstance, that its saline contents are increased
by a west wind, but still more so by a gale from the north west.

Some philosophers have endeavoured, but to little purpose, to account,
from second causes, for the saltiness of the ocean. Dr. Halley persuaded
himself that it might have been gradually acquired, in very minute
portions, by a deposit of salt washed down from the land by rivers, and
that, as it could not be carried off by evaporation, instead of being
diminished, it must be constantly increasing. But this idea of salting
the sea with fresh water, is, to say the least of it, somewhat absurd,
more particularly as it presumes that the sea was originally
unimpregnated with salt. Had this been the case, the putrefaction of the
immense mass of animal and vegetable substances which it gradually
contained, would, in a short time, have proved fatal to the whole
inhabitants of the earth.

The temperature of the sea, although it must necessarily vary in the
different seasons, is much more uniform than that of any inland water
exposed to the atmosphere. This is, in a great measure, attributable to
its vast body of water, and the perpetual agitation to which it is
exposed.

Sea water, when congealed by frost, is found to reject all, or nearly
all, its saline particles; and consequently, when thawed, its ice yields
water so fresh that it may be drunk without unpleasantness. The freezing
of sea water is not unfrequently practised in the northern parts of the
world, with a view to lessen the trouble and expense of extracting salt
from it, for domestic and other uses (202). Salt water may likewise be
rendered fresh and palatable by distillation, a mode which is now very
generally practised at sea.

The sea shore has of late become so much frequented by invalids, for the
purpose of bathing, that there is scarcely a fishing village, on the
whole extent of our coast, but which is provided with some accommodation
for bathers. As a cold bath, sea water is employed, with advantage, in
all those cases of debility for which cold bathing has, in general, been
recommended. It is also used as an external application in tumours and
some other complaints; and, taken internally, as a remedy in various
disorders.

It is to sea water that we are chiefly indebted for the salt which we
use at table, and for all the purposes of domestic economy (202). From
this water is also obtained those salts used in medicine, called
Glauber’s (203) and Epsom salts (199).


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                       ORDER III.—MINERAL WATERS.


                    1. THE MORE SIMPLE COLD WATERS.

280. _MALVERN WATER is a simple cold water, perfectly bright and
pellucid: it has an agreeable, and somewhat pungent flavour; but, in
other respects, it does not differ in taste from pure and good soft
water._

_It contains carbonic acid (26), and a very small portion of earth,
either lime or magnesia; but, the carbonic acid perhaps excepted, the
foreign bodies are less in quantity than those even of our common spring
water._

The spring from which this water principally issues is denominated the
Holy Well: and is situated high up the hill, about midway between the
villages of Great and Little Malvern, in Worcestershire.

Both as an external and internal application, the waters of Malvern have
been considered beneficial in many obstinate complaints. It is a
singular circumstance respecting them that, notwithstanding their
apparent purity, if they be exposed to the air in an open vessel, they
will soon acquire a fetid and unpleasant smell.

Malvern is principally frequented during the summer season.[5]

Footnote 5:

  Adjoining to Great Malvern, and a little higher up the hill, there is
  a very light and pleasant _chalybeate water_.


                    2. THE MORE SIMPLE WARM WATERS.

281. _BRISTOL HOT─WELL WATER is pure, warm, and slightly acidulated,
clear, sparkling, and agreeable to the palate, but without any very
decided taste. It is also destitute of smell. When poured into a glass
it sends forth numerous air─bubbles. The heat of this spring is very
moderate, the average_ _being about 74° of Fahrenheit’s thermometer; and
this heat does not sensibly vary during summer or winter._

_The foreign contents of the hot─well water are muriat of magnesia,
common salt, Glauber’s salt, sulphat of lime (192), and chalk: but these
are in extremely small quantity. It also contains at the rate of about
thirty cubic inches of carbonic acid gas, or fixed air (26), in every
gallon._

This water springs from the bottom of the southern extremity of St.
Vincent’s rock, a lofty cliff of limestone situated on the north bank of
the river Avon, and about a mile below the city of Bristol. And,
although it is considerably higher than the river, it is so far affected
by the spring tides as to become, thereby, in some degree turbid. The
discharge of water amounts to about forty gallons in a minute.

There is another spring at _Clifton_, on the summit of the same hill,
from the bottom of which the waters of the hot─well issues. This is
called the _Sion spring_, and is one or two degrees colder, but, in
other respects, it very nearly resembles the water of the hot─well.

Its discovery was somewhat remarkable. A Mr. Morgan, an attorney of
Bristol, having erected a house near the spot, sunk a well for the
supply of his family with water. The workmen had proceeded to the depth
of nearly 240 feet without success, when they were suddenly alarmed by
the gushing forth of such an abundance of water that they were compelled
to retreat with precipitation. The proprietor was so far disappointed of
his hopes as to find that this was a spring of warm instead of cold
water. But the circumstance induced him to erect an engine to raise the
water for medicinal purposes; and, since that period, a pump room and
bathing houses have been prepared for the accommodation of visitors.

The water of each of these springs, besides being used medicinally in
pulmonary consumptions and other complaints, is employed very
extensively at table, and for all domestic purposes. It is remarkable
for softness and purity; and, from its quality of continuing untainted
for a great length of time, even in hot climates, is a valuable water
for long voyages, and is accordingly exported in considerable quantities
to distant parts.

The season of general resort to Clifton and the hot─wells is from about
the middle of April to the end of October.

282. _MATLOCK WATER is a simple warm water, which, in its sensible
properties, exclusive of its temperature, which is only about 66° of
Fahrenheit, is scarcely different from good spring water. It is
beautifully clear, and exhales no steam, except in very cold weather._

The medicinal virtues of this water have chiefly been ascribed to its
temperature. Its supply is very copious, and from several different
sources. Though recommended in some internal complaints, it is
principally employed as a bath; and, in this respect, it forms a medium
betwixt the waters of Bath or Buxton and those of the generality of cold
baths.

Matlock, which is a beautifully romantic village, situated in a hilly
part of Derbyshire, and at the distance of 143 miles north of London,
was first brought into public notice about the year 1698, shortly after
which period the first bath was erected. It is chiefly frequented from
the month of May to that of October; or, if the weather continue fine,
till near the beginning of November.

283. _BUXTON WATER is a simple warm water, which contains so little
foreign matter, as scarcely to be distinguishable from common spring
water heated to the same temperature. It has neither smell nor taste;
and, though it sparkles a little in the glass, when first drawn, this is
not apparently more than what is observable in the water of many common
springs._

_Its temperature, in the bath called the Gentleman’s bath, is invariably
82°._

Buxton has been celebrated, for its warm springs, nearly two centuries
and a half. As early as the year 1572 a treatise on their virtues was
published: this states them to have been at that time much resorted to
by persons from all the adjacent counties. The water is employed both
externally and internally, and to great extent. Its principal value, as
a bath, arises from its very copious supply, its purity, and its high
temperature. The sensation which is felt from bathing in it is
considered to be such as would be experienced from any bath heated to
the highest temperature which is compatible with giving some sensation
of cold when the body is first plunged into it. This water is also used
as an internal medicine; and is frequently used by the inhabitants as
their common beverage, and for such domestic purposes as its hardness
will admit.

There are several springs and several distinct baths; but the original
and most ancient of them is called St. Ann’s Well, and is enclosed in an
elegant stone building. These waters are frequented by persons afflicted
with the rheumatism, gout, diseases of the alimentary organs, and
kidneys, and various other complaints: and the chief influx of company
is during the summer and autumnal months.

The situation of Buxton is in a narrow and funnel─shaped valley,
surrounded by wild, bleak, and dreary mountains, in the midst of the
county of Derby, and about 160 miles north of London.


                  3. HOT CARBONATED CHALYBEATE WATER.

284. _BATH WATER is a hot carbonated chalybeate. When first drawn, it
appears clear and colourless, nor does it afford any signs of briskness
or effervescence. The temperature of the water drawn from the King’s
Bath, which is that usually employed for drinking, is 116° of
Fahrenheit, and that of the Cross Bath is 112°. No odour whatever is
perceptible from a glass of fresh water; but from a large body of it the
nose is affected by a slight degree of pungency. When the water is hot
from the pump, it fills the mouth with a strong chalybeate impression
without any pungency, and accompanied with scarcely any kind of saline
taste; and, what is remarkable, as soon as the water cools, the
chalybeate taste is entirely lost, and nothing but an extremely slight
saline sensation remains upon the palate._

_The foreign contents of Bath water are sulphat of lime (192), chalk,
Glauber’s salt (203), and common salt; together with a very small
portion of oxide of iron (21), yet sufficient to give iron mould stains
to the linen of the bathers. The water curdles soap, and is so hard as
to be unfit for many domestic purposes._

The city of Bath has been celebrated for its hot springs even from the
time of the Romans. These are of higher temperature than any within the
British dominions; and indeed are the only natural waters which we
possess that are at all hot to the touch, the other thermal waters being
of heat below the animal temperature.

There are three principal sources of these waters, called the King’s
Bath, the Cross Bath, and the Hot Bath; and they differ slightly in
their properties. The springs arise within a short distance of each
other, at the lower part of the city; and yield so copious a supply that
all the large reservoirs used for bathing are filled every evening with
water fresh from their respective fountains.

The application of the water externally is either general or local. The
latter consists in pumping it for a considerable time on the part
affected. This is called _dry pumping_, because in it only one part of
the body is wetted, whilst the rest is kept dry; and in many cases, it
is found an excellent remedy.

The diseases for which these waters are resorted to are very numerous,
and are amongst the most important and difficult to be cured that come
under medical treatment.


                   4. HOT ALKALINE SULPHUREOUS WATER.

285. _AIX─LA─CHAPELLE or AKEN WATER, is an alkaline sulphureous water,
much hotter than that of any of the springs in England, varying in
temperature in the different baths from 112° to 143°. It has a saline,
bitterish, and somewhat alkaline taste; and its smell precisely
resembles, but is greatly more powerful than, that of Harrowgate water
(299)._

_It contains a small quantity of chalk, common salt, and carbonat of
soda (201), the latter of which renders it soapy to the touch. But the
most striking feature in this water is_ _the unusual quantity of sulphur
which it contains; and which is so extremely volatile on the application
of heat, that none of it is left in the residuum after evaporation. In
this water there is also a considerable portion of carbonic acid._

The city of Aix─la─Chapelle is in the circle of Westphalia, betwixt the
rivers Meuse and Rhine, about seventy miles east of Brussels, and in a
rich and fertile country. Its waters have been in great medical repute,
and have attracted a numerous concourse of visitants for many centuries
past. Their reputation was so well established, even in the time of
Charlemagne, that he frequently resided at Aix: and he is said to have
been so much delighted in the use of the waters as to have sometimes
even held his levee at the baths.

In this city, and in the small territory that belongs to it, there are
several sources of hot water. Of these the principal spring is enclosed
in a stone cistern, which is vaulted and almost conical at the top, and
the parts of which are connected with the utmost care, to prevent the
vapour from escaping. From this spring the water flows, in a copious
stream, into several spacious and elegant baths, in the different parts
of the city, distinguished by the names of the Emperor’s Bath, the
Nobles’ Bath, the Poor’s Bath, and other appellations. In most of these
there is every necessary apparatus for bathing by immersion, for vapour
bathing, and for pumping on any particular parts of the body.

The water rises, with great quickness, from the springs, and sends forth
bubbles of air, which burst with a slight noise when they reach the
surface. It is at first perfectly colourless and pellucid, and emits a
large portion of steam, and with it a strong sulphureous smell, which is
perceptible at a great distance.

Its temperature is so high, that, in the large baths, it requires to
stand from fifteen to eighteen hours before it is sufficiently cooled
for tepid bathing; and it is one of the few natural springs which are
hot enough to be employed as a vapour bath without the addition of
artificial heat. On standing to cool, it gradually loses its clearness,
acquires a milky hue, and deposits an earthy sediment, which is entirely
calcareous. At the same time it loses its offensive smell, and, when
cold, has scarcely any odour.

Wherever a large quantity of this water passes hot from the spring
through a confined place, the upper covering becomes encrusted with
sulphur. This is particularly the case with respect to the dome of the
vault that encloses the great source which supplies the Emperor’s bath,
and which is opened, from time to time, for the purpose of having the
sulphur brushed off.

From the waters of Aix─la─Chapelle, though only internally used, the
body acquires a sulphureous smell; and even silver worn in the pocket
becomes tarnished.

286. _BORSET WATER is of two kinds. One of these resembles the water of
Aix in every respect, except as to the impregnation of sulphur, which is
much weaker: its temperature is 132°. The other contains no sulphur: it
is, however, equally alkaline, and the heat is as high as 152°, which
much exceeds the hottest of the waters of Aix._

Both these waters are used by fullers and cloth─workers, on account of
the convenience they afford, without expense, of a sufficiency of hot
and somewhat alkaline fluid which is well adapted for the cleansing of
woollen cloth.

In the latter of the above─mentioned springs a large portion of earth is
suspended. This, as the water cools, is deposited, and forms hard
incrustations of considerable thickness round every substance with which
it comes in contact. It is not, however, on this account found less
useful for the scouring of cloth, boiling of vegetables for the table,
or any of those domestic purposes for which soft water is required.

In this spring there is a considerable portion of carbonic acid gas, or
fixed air (26), which is continually escaping from the fresh water, and
is in sufficient quantity to corrode, in a short time, the leaden
covering that is used for the vapour baths, and any iron within its
reach.

After having supplied several baths, the stream flows into a large fish
pond, where it is still of blood heat. In this pond we are informed that
carp and tench multiply very fast, and grow to an enormous size; but
that their flesh is soft and without flavour, until they have been
removed, for about six months, into a pond of cold water, where they
become perfectly firm and good for the table.

In their medicinal application these waters are chiefly employed
externally, and their great heat allows of every convenience for vapour,
hot, warm, and tepid bathing. The village of Borset, or Bordscheit, in
which they are found, is situated about a quarter of a mile south of
Aix─la─Chapelle (285).


          5. HOT, SALINE, HIGHLY CARBONATED CHALYBEATE WATER.

287. _THE VICHY WATERS are hot, saline, and chalybeate. They vary in
some degree in the different springs, have a salt and somewhat bitter
taste, and a considerable pungency of smell. They are alkaline, and
about the temperature of 120°._

There are, at Vichy, a small town on the banks of the river Allier,
about 180 miles south─east of Paris, no fewer than six different springs
of hot water, which vary somewhat in their temperature, and in the
proportion of their foreign contents. The valley in which this town is
situated is highly fertile and beautiful, and abounds in vineyards and
fruit─trees.

It is remarkable that sheep, cows, and other animals, crowd to drink
this water with great eagerness, and even to lick the stones and sides
of the channel through which it flows. Their partiality for it is so
great that, at certain times, they are known to swim across the river
Allier, in considerable numbers together, without even tasting of that
water, and to proceed, without interruption onward, until they reach
this their favourite beverage.

288. _CARLSBAD WATER is hot, saline, and chalybeate, having an
unpleasant alkaline and bitter taste, though scarcely any smell. Its
constant temperature is 165°. It contains chalk, Glauber’s salt (203),
common salt, and carbonat of soda (201), together with a small portion
of iron; and carbonic acid gas, or fixed air (26), in considerable
quantity._

The town of Carlsbad, situated on the river Eger, in Bohemia, and its
springs (which have the name of _Caroline baths_), received their
appellation from the Emperor Charles the Fourth, who is said to have
himself discovered the latter, in the year 1370, whilst hunting; and,
since that period, few waters have more engaged the attention of
chemists and physicians than these. Carlsbad is now much frequented
during the summer months, and has good accommodations as a watering
place. Its water is remarkable for a rapid and copious deposition of
calcareous earth, which takes place always on cooling, and forms a very
hard and beautiful crust on the inner surface or tube of any channel
through which it flows; and forms petrifactions round moss, pieces of
straw, or other extraneous substances which are put into the stream,
even for so short a time as twenty─four hours. All the iron which the
fresh water contains is also precipitated by cooling, and rather sooner
than the calcareous earth. A very fine laminated calcareous stone in
variegated colours is thus formed in large masses around the channel of
the stream, which, when polished, is almost equal in beauty to jasper.

Of the hot springs of this neighbourhood the principal is called the
_Sprudel_. It boils up, with great violence, and discharges about 352
cubic feet of water hourly, through a curious natural vault or
incrustation which it has gradually formed. This water supplies the
greater number of the baths. The other springs are, in general, of much
lower temperature: they do not exceed from 114° to 125°, and they differ
somewhat from each other in their chemical properties. They all contain
a large portion of carbonic acid gas, or fixed air, and this is given
out in such quantity by the water, that it fills several caverns, in the
rocks adjoining to the springs, rendering them fatal to all animals
which incautiously enter them.

The waters of Carlsbad are used for the removal of a great variety of
disorders, but particularly such as are connected with indigestion. They
are likewise used in obstructions of the bowels, and diseases of the
kidneys. About five pints, divided into fourteen portions, are, on an
average, drunk by each individual every day.

The Sprudel spring is better than that of any mineral waters which are
employed medicinally. It requires to be considerably cooled before it
can either be used as a bath, or drunk. Its heat is such that it is
occasionally employed, in place of water artificially heated, for
several domestic purposes, such as the scalding of fowls and hogs, the
feathers and hair of which it immediately loosens.

Several hundred pounds weight of Glauber’s salt are annually prepared
from this water.


                        6. SIMPLE SALINE WATERS.

289. _SEDLITZ WATER is very salty and bitter. It contains a small
portion of chalk, some sulphat of lime (192), carbonat of magnesia,
muriat of magnesia, and a very great proportion of Epsom salt (199), to
which its bitter taste and medicinal virtues are principally
attributed._

The spring for which the village of Sedlitz, in Bohemia, has long been
celebrated, was, for many years, wholly neglected by the inhabitants, on
account of the bitter and nauseous taste of its water, which rendered it
unfit for nearly all domestic purposes. Its virtues, as a medicine, were
first brought into notice about the year 1721, by Hoffman, the
celebrated Prussian physician.

This water is considered a valuable remedy in cases of indigestion, for
removing scorbutic humours, and in several other complaints.

290. _EPSOM WATER is saline, and partakes, in some degree, of the nature
and qualities of Sedlitz water, but it is by no means so powerful. It is
transparent and colourless; and, when first taken into the mouth, has
scarcely any taste, but it leaves a decidedly bitter and saltish taste
on the palate._

_This water contains sulphat of magnesia, or Epsom salt (199), selenite,
and a small portion of chalk._

Although the Epsom waters, on account of their deficiency of strength,
are now scarcely ever employed in medicine, yet they were among the
first saline cathartic springs which were brought into use in this
country. The salt to which they owe their property, and which is known
throughout Europe by the name of Epsom salt, was, for many years,
prepared almost exclusively from them and from Sedlitz water. But the
quantity which they supplied was found so very inadequate to the
increasing demands for this salt in medicine, that Epsom Salt has, for
some time past, been manufactured from sea water.

Epsom water, if closely corked, may be kept for several months without
injury: but, otherwise, it soon becomes putrid. The spring from which it
issues is situated about half a mile from the town of Epsom in Surrey,
sixteen miles south of London.

There are, in the neighbourhood of London, many springs of similar
quality to this of Epsom: of these the principal are at Acton, Kilburne,
Bagnigge Wells, and formerly the Dog and Duck in St. George’s Fields;
but they are, in general, so weak as to render very large quantities of
the water necessary to produce any sufficient medical effect.


                  7. HIGHLY CARBONATED ALKALINE WATER.

291. _SELTZER WATER is an highly carbonated alkaline water. When fresh,
or well preserved, it is perfectly clear, and sparkles much when poured
into a glass. It is somewhat pungent, slightly saline, and a little
alkaline to the taste._

_It contains chalk, carbonat of magnesia, carbonat of soda (201), and
common salt; and more carbonic acid gas, or fixed_

_air (26), than any water hitherto known. It is hard, and curdles with
soap._

The spring which supplies this water is situated in Nieder Seltzer, a
village in a fine woody country, within the bishopric of Treves; and
there are few mineral springs which have acquired so much celebrity for
medical virtues as this. The diseases, for the removal of which it has
been successfully applied, are too numerous to be here particularized.

To the taste it is very agreeable, and when drunk in moderate quantity,
it exhilarates the spirits, increases the appetite, and produces no
particular determination to the bowels. It is to the strong impregnation
with carbonic acid, and the small proportion of soda which it contains,
that its most important benefits are owing.

If it be closely corked and sealed, Seltzer water may be kept without
injury, or even alteration, for a very considerable time; but, if
exposed to the air, it soon becomes fetid. It is used as a common drink
at table in many parts of Germany and Holland, and is even brought into
England in stone bottles, each containing about three pints. A large
proportion of Seltzer water, either genuine or artificial, is consumed
in this country.


                         8. CHALYBEATE WATERS.

292. Are such as contain a portion of iron. This is easily detected by
the property which it has of striking a black colour with tincture of
nutgalls.

293. _TUNBRIDGE WATER is a carbonated chalybeate, the small portion of
iron which it contains being held in solution by carbonic acid (26). It
is, however, neither brisk nor acidulous. To the taste it is simply
chalybeate; and that only in a slight degree._

_Its foreign contents are oxide of iron (21), a small portion of common
salt, muriat of magnesia, and sulphat of lime (192), carbonic acid gas
or fixed air (26), and other gases, but these only in small quantity._

Tunbridge Wells is a populous village, situated in a sandy but romantic
valley in the county of Kent, about five miles from the town of
Tunbridge, and thirty─six miles south of London. There are, at this
place, many chalybeate springs, all of which nearly resemble each other
in their chemical properties. Two of them, however, are chiefly used,
each of which yields about a gallon of water in a minute.

When first taken from the stone basin into which it flows, the water is
perfectly clear and bright, and exhales no particular smell. It does not
sparkle in the glass, but a few bubbles slowly separate, and adhere to
the sides of the vessel. When it has stood for some hours exposed to the
air, it becomes turbid, and otherwise undergoes a very material change.
As it does not properly curdle soap, it may be denominated a soft water.

The original discovery of this water, as to its medical properties, is
usually considered to have been in the reign of James the First. The
season for drinking it commences as early as March or April, and
continues till November.

_294. SPA WATER, the celebrity of which has given a general appellation
to most other mineral springs, is a highly carbonated chalybeate water,
which contains a great proportion of carbonic acid (26). It has an
agreeable acidulous taste, mixed with a strong impression of chalybeate,
which remains on the palate for a considerable time after it has been
drunk._

_It contains oxide of iron (21), chalk, carbonat of magnesia, carbonat
of soda (201), and common salt, together with about forty─five parts in
a hundred of carbonic acid gas or fixed air (26); and is sufficiently
soft to mix both with milk and soap without curdling._

Spa is a small but celebrated town in the Netherlands. It is situated on
the little river Weze, about twenty miles south─east of Liege, and seven
miles south─west of Linsburg; and is surrounded by rude and uncultivated
mountains, many of which are covered with wood, and others with heath or
morasses. In its neighbourhood there are no fewer than sixteen mineral
springs, five of which are more celebrated than the others. The most
copious and most frequented of the whole is the _Pouhon spring_, in the
market─place of Spa. This is a large, slow, and deep spring, the descent
to which is by several steps. In cold dry weather the water, when first
taken up, appears colourless and perfectly transparent: it scarcely
sparkles, but it soon covers the inside of the glass with small
air─bubbles, which it also emits very copiously when shaken. During
moist weather the surface of the well appears somewhat turbid: and, on
the approach of rain, a whistling or humming noise is heard, which is
called by the country people the music of the spring.

If this water be bottled, and then set in a warm place, it will
generally force out the cork, with a loud explosive noise. In preserving
it for exportation, it is consequently necessary to wire the corks
firmly down. In this state, if well cemented, it may be kept perfectly
good for more than two years.

It is somewhat remarkable, respecting this water, that if it be taken in
a full draught, particularly in hot weather, or upon an empty stomach,
it produces a swimming in the head, and a degree of intoxication, which
frequently continues for half an hour or upwards, and is very similar to
that which arises from the drinking of spirituous liquor, but it does
not leave the same debility.

295. _PYRMONT WATER is a highly carbonated chalybeate. When recently
taken from the spring, it is clear and pellucid, and sends forth a
copious stream of bubbles for a considerable time. In this respect it
far exceeds any of the mineral waters with which we are acquainted. Its
taste is pleasant, being strongly acidulated, and having a pungency not
unlike that of brisk Champagne wine; but it is at the same time strongly
chalybeate, and a little bitterish._

_It chiefly contains oxide of iron (21), chalk, carbonat of magnesia,
Epsom salt (199), sulphat of lime (193), and common salt, and a great
proportion of carbonic acid gas, or fixed air. It is very hard._

Pyrmont is a town of Westphalia, and about thirty─eight miles south─west
of Hanover. It is the capital of a county, has a strong fort, and is
well known on account of its mineral springs.

The water which issues from these springs constantly emits so large a
quantity of gas as to have a sensible pungency of smell to those who
stand around, and even to make the water─servers giddy. It forms an
atmosphere over the surface of the well which proves fatal to ducks and
small birds that attempt to swim across. The gas contained in the water
is estimated to be nearly equal in bulk to the water. It is owing to
this, that Pyrmont water, if bottled and well corked, and afterwards
removed into a warm place, will frequently burst the bottles.

When drawn fresh from the spring and drunk copiously, it produces a
temporary kind of intoxication. It also enlivens the spirits and
increases the appetite. This water is sent in bottles, by the Weser, to
Bremen, whence it is exported to various parts of the world.

296. _CHELTENHAM WATER is a saline, carbonated, chalybeate, which has a
slight sulphureous smell, and a brackish, somewhat bitter, and
chalybeate taste, but no briskness nor pungency._

_Its foreign contents are Glauber’s salts (203), muriat and carbonat of
magnesia, common salt, and oxide of iron, together with a portion of
carbonic acid gas, and some other kinds of gas._

The original discovery of the mineral spring at Cheltenham was about the
year 1716. The water of this spring issues slowly, and in a scanty
stream of not more than 35 pints in an hour, from a bed of sand
intermixed with blue clay. The well is sunk to the depth of six feet,
and is excluded from communication with the external air. This spring is
denominated the _Old Spa_.

In the year 1788, on digging a well for a private house, another spring
was accidentally discovered, which is of nearly the same nature as this,
and produces a much more abundant supply of water. It is about a hundred
yards distant from it, is upwards of forty feet deep, and is drawn by a
pump.

When Cheltenham water is fresh drawn, it appears tolerably clear, though
not perfectly transparent. After standing some time, it becomes more
turbid, and air─bubbles, in small quantity, rise from it. It contains
more salt than perhaps any other waters, except those of the sea and
some brine springs; and by far the greatest part of the salts are of a
purgative kind. It is also a very strong chalybeate, and has a slight
impregnation of sulphur.

This water cannot long be kept, nor can it be transported to any
distance without being materially altered. In order, however, to reduce
its valuable parts to a more convenient form, for carriage and keeping,
the salts are extracted from it on the spot, by evaporation, and
crystallizing the residuum. These salts are much used, in addition to
the fresh water, for the purpose of increasing its operation on the
bowels.

Cheltenham is a small town in the county of Gloucester. It is about
ninety─five miles north─west of London, situated in a sandy vale,
surrounded with hills of moderate height, and in the midst of a fertile
and well cultivated country.

297. _BRIGHTON CHALYBEATE WATER is a vitriolated chalybeate, which, when
fresh, has a peculiar and faint smell not uncommon in ferruginous
waters, and a strong though not unpleasant chalybeate taste._

_It contains sulphat of iron or vitriol (208), sulphat of lime (182),
common salt, muriat of magnesia, siliceous earth, and a certain portion
of carbonic acid gas (26)._

Brighton is a well─known market─town, situated on the coast of Sussex,
and about fifty─four miles south of London. The chalybeate spring is at
Wick, on the declivity of a small eminence nearly a mile west of the
town, and a quarter of a mile from the sea. A small but neat building
has been erected immediately over the spot from which the water issues,
and where it is received, a few feet under ground, into a basin of
Portland stone. This reservoir contains only a few gallons of water, but
it fills again almost as soon as it is emptied.

The water is so hard as instantly to curdle soap. It is considered
useful in cases of debility, indigestion, and such diseases for which
chalybeate and tonic remedies are required. The sea─bathing at Brighton
is, in many cases, an additional and important advantage to those
persons who use the chalybeate water.


                      9. COLD SULPHUREOUS WATERS.

298. HEPATIC, or SULPHUREOUS WATERS, are so strongly impregnated with
sulphur, united either to hydrogen (45), or to an alkali, or both, as
thereby to acquire a very sensible smell and taste. They have the
property of blacking silver and lead; and are immediately known by the
smell, which is very fetid, and like that which arises from the scouring
of a foul gun─barrel, or, as some persons suppose, like the smell of
rotten eggs.

The taste of these waters is peculiar, and rather sweetish. They
constitute a drink which, at first, is very unpalatable, but which, by
habit, is soon reconciled to the drinker. None of them will bear
carriage to any distance.

299. _HARROWGATE WATER is a cold sulphureous water, which has a very
strong and fetid smell, like that of a damp rusty gun─barrel. To the
taste it is bitter, nauseous, and strongly saline._

_Its foreign contents are common salt, muriat of lime, muriat of
magnesia, chalk, carbonat of magnesia, Epsom salt (199), carbonic acid
gas, or fixed air (26), azotic gas, and sulphureted hydrogen gas._

There are, at Harrowgate, four distinct sulphureous springs, which
appear to have their rise in a large bog, at a small distance from the
wells. The water of all these springs is similar in its properties and
its distinguishing characters, but as one of them is more strongly
impregnated with sulphur than the others, this alone is used for
drinking, whilst the other three are employed to supply the baths.

When the water of the former of these springs is first taken up, it is
perfectly clear and transparent; and sends forth a few air─bubbles.
Notwithstanding both its nauseous smell and taste, such is the power of
habit in reconciling it to the palate, that, after a little while,
nearly all persons who drink this water do it without disgust.

When exposed to the air it loses its transparency, and assumes a
somewhat greenish colour: the sulphureous odour abates; and, at last,
the sulphur is deposited on the bottom and sides of the vessel in which
it is kept.

Such is the nature of Harrowgate water that a secret correspondence has
often been carried on by means of it. A letter written with solution of
sugar of lead is illegible; but if dipped into this water the writing
will not merely become visible, but, in a short time, will appear almost
black. Hydrogen has the property of reviving the metallic oxides: hence
also it is that ladies who have used metallic cosmetics have become of a
dark tawny colour by bathing in these waters.

Harrowgate has long been celebrated for its sulphureous waters. It has
also two very valuable chalybeate springs, called the _Old Spa_, and the
_Tewit Well_, the water of which was formerly used internally, whilst
the other water was confined to external use. But, at present, the
latter is employed to very great extent as an internal medicine.

The two villages of High and Low Harrowgate are situated in a pleasant
open country, in the centre of the county of York, near the town of
Knaresborough, and about 212 miles north of London.

300. _MOFFAT WATER is a cold sulphureous water, the smell of which is
precisely similar to that of Harrowgate water, and the taste simply
saline, and without any bitterness._

_Its foreign contents are common salt, together with carbonic acid gas,
azotic gas, and sulphureted hydrogen gas. It is consequently very simple
in its composition._

Moffat is a village situated, at the head of a valley, on the banks of
the river Annan, and about fifty─six miles south─west of Edinburgh. It
is surrounded by hills, some of which are very lofty. This village has
obtained so much celebrity, on account of its waters, as to be
considered the Harrowgate of North Britain. These issue from a rock
which is at a little distance below a bog, whence, probably, they derive
their sulphureous ingredients. The principal spring is contained within
a stone building, and affords a sufficient quantity of water to supply
every demand. It is drawn by a pump.

When the water is first taken from the well it appears somewhat milky
and bluish. It sparkles a little; but, on being exposed to the air, it
becomes turbid, and throws up a thin film, which, on examination, will
be found pure sulphur. This change takes place even in close vessels, so
that it cannot be sent to any distance with advantage.

The common people so much esteem this water that many of them drink at
the rate of from six to ten quarts of it in a morning, and one instance
has been stated of a person drinking thirty─two quarts of it in eight
hours.


────────────────────────────────────────────────────────────────────────




                                 INDEX
                                 TO THE
                             FIRST VOLUME.

                                ───────

 Acid, sulphuric, 12; how made, properties and uses of, 145

 Acid, phosphoric, 12

 Acid, carbonic, 12

 Acid, fluoric, 13; how made, properties and uses of, 120

 Acid, boracic, 13

 Acid, muriatic, 13; How made and uses of, 132

 Acid, nitric, 14; How made, and uses of, 138

 Adamant. See Diamond.

 Adamantine spar. See Corundum.

 Adularia, description and uses of, 70

 Agate, description, uses, &c. of, 61, 62
 ——, different kinds of, 63

 Alabaster, description and uses of, 117
 ——, calcareous, account and uses of, 111, 112

 Alkalies, 18

 Alumine, 15, 123

 Alluvial depositions, 235

 Alum, description and uses of, 123, 124
 ——, Roman and Roche, 123
 ——, how procured and made, 123

 Amalgams, what they are, 176

 Amazon stone, description and use of, 69

 Amber, description and history of, 161
 ——, where found, and how wrought, 162
 ——, uses and properties of, 163
 ——, varnish, 163
 ——, gum animè often mistaken for, 164

 Amethyst, oriental, 32
 ——, common, description and uses of, 48

 Amianthus. See Asbestos.

 Ammonia, muriat of. See Sal─ammoniac.

 Antimony, description of, and whence obtained, 215
 ——, how prepared, and uses of, 216, 217
 ——, butter and glass of, 217
 ——, oxides of, 217

 Antimonial powder, of what composed, 217
 —— wine, how prepared, and use of, 217

 Aqua marine, description, value, and uses of, 39, 40
 ——, where found, how cut and set, 40

 Aqua fortis, mode of manufacturing, and uses of, 138

 Aqua regia, of what made, 139

 Argil, 15

 Arsenic, description of, and whence obtained, 212
 ——, how prepared for use, and the uses of, 213
 ——, poisonous effects of, how counteracted, 213
 ——, how to know from any other substance, 213

 Asbestos, use of, for making incombustible cloth, &c., 93, 94

 Asphalt, description of, where found, and uses of, 149, 150

 Avanturine, description, uses, and value of, 50
 ——, imitations of, how made, 50

 Axestone, description and use of, 89

 Azure stone, description and uses of, 67, 68
 ——, imitation of, how made, 68


 B.

 Barilla. See Soda.

 Barium, 17

 Barytes, description and uses of, 120
 ——, sulphat of, 121

 Basalt, description and uses of, 95, 96

 Bath stone, description and uses of, 114

 Bell metal, of what made, 188

 Beryl. See Aqua marine:aqua─marine#.

 Betton’s British oil, what it is, 146

 Biscuit porcelain, what it is, and how made, 75

 Bismuth, description and uses of, 217, 218
 ——, singular fusible metal prepared from, 218
 ——, experiment with, illustrative of metallic crystal, 234

 Bitumen. See Asphalt, 149
 ——, elastic, 149

 Black chalk, description and use of, 80

 ——, pencils, how made, 80

 Black tin, what it is, 200

 Bloodstone, description and uses of, 59
 ——, singular specimen of, 59

 Blue John. See Fluor spar.

 Blende, 209

 Bole, description and uses of, 87

 Bologna phosphorus, or Bononian stone, how prepared, and properties of,
    121

 Boracic acid, 13

 Borax, description of, whence and how obtained, 134
 ——, preparation and uses of, 135

 Bottles, how made, 55

 Brass, how made, and uses of, 187
 —— wire, properties and uses of, 187

 Bricks, how made, 72

 Brimstone. See Sulphur.

 Bristol diamonds, 47

 Bronze, how made, and uses of, 187

 Burning spring, description of one in Shropshire, 147

 Burr─stone, or millstone, description of, 44
 ——, where found, uses of, and how split, 45

 Buxton diamonds, 47


 C.

 Cachalong opal, description and use of, 65

 Calamine, description and uses of, 209─211

 Calcareous substances, 17, 97

 Calcedony, description and uses of, 56, 57

 Calcium, 18

 Calomel, how made, and uses of, 177

 Caloric, 9

 Calp. See Lias.

 Caoutchouc mineral, 149

 Carbon, 20

 Carbonats, 13

 Carbonic acid, 12

 Carbuncle, 43

 Carnelian, description, uses, and value of, 57

 Cat’s─eye, description of, how cut, and uses of, 50

 Cave of Fingal, account of, 96

 Cairn gorum crystal, whence obtained, how wrought, and uses of, 49

 Ceruse. See White lead.

 Chalk, description and uses of, 99
 ——, black, description and uses of, 80
 ——, red, how prepared, and uses of, 199

 Chinese grotesque figures, of what made, 84

 Choke damp in coal─mines, what it is, how produced, and how to prevent
    the injurious effects of, 154

 Chrysoberyl, description, value, and uses of, 35

 Chrysolite, description of, how cut, and uses of, 95

 Chrysoprase, description of, how cut, imitations, and uses of, 58, 59

 Cinnabar, artificial, how manufactured, and use of, 177

 Cinnamon stone, 44

 Clay, various kinds, description and uses of, 71, 72

 Clay─slate. See Roofing─slate.

 Coal, description of, where found, and value of, 151
 ——, supposed origin, and various uses of, 155

 Coal mines, account of, 152

 Coal trade, history, &c. of, 154─156

 Coal, cannel, what, why so called, and uses of, 157
 ——, stone, Kilkenny, or Glance, and Welsh, 158
 ——, Bovey, or brown, 158
 ——, pitch, 158
 ——, parrot, 157

 Cobalt, account of, whence obtained, and uses of, 220
 ——, oxide of, 221

 Coke, uses of, 156

 Copper, description and ancient uses of, 183
 ——, mines of Anglesea described, 183
 ——, how extracted from the ore, &c., 183
 ——, uses of, 185, 186
 ——, vessels, in what respects pernicious, 185
 ——, oxide of, uses of, 186
 ——, alloys of, 186
 ——, white, of what made, and uses of, 188
 ——, how to gild, 172
 ——, sulphat of. See Vitriol, white.

 Copperas. See Vitriol─green.

 Cornish diamonds, 47

 Corrosive sublimate, what it is, and uses of, 177

 Corundum, description and uses of, 34

 Crystal, description and uses of, 45─47
 ——, where found, how wrought and polished, 46, 47

 Culm, what it is, and the uses of, 157


 D.

 Derbyshire spar. See Fluor spar.

 Diachylon plaster, how made, and uses of, 206

 Diamond, description of, 23
 ——, where found, how obtained, and how known, 23, 24
 ——, properties of, 24
 ——, how cut, polished, and set, 26
 ——, value and uses of, 26, 27
 ——, account of several remarkable diamonds, 27, 28, 29
 ——, Buxton, Cornish, and Carrara diamonds, 47, 102

 Drawing slate. See Black chalk.

 Dropping well at Knaresborough, 113

 Dutch gold, how made, 187

 Dykes, mineral, 3


 E.

 Earth, 14

 earthenware, how manufactured, 71

 Eau─de─luce, of what made, 164

 Egyptian pebble, description and uses of, 61

 Electron of the ancients, what it was, 162

 Emerald, description of, where found, how set, and how valued, 38
 ——, oriental, 32
 ——, false, 49

 Emery, description, properties, and uses of, 33
 ——, how prepared for use, 33
 ——, red, 43

 Epsom salts, description of, how made, and uses of, 126


 F.

 Faults, in mining, what they are, 3

 Felspar, common, description and uses of, 69
 ——, Labrador, 69

 Figure stone, description and uses of, 84

 Filtering stone, of what made, 233

 Fire damp in coal─mines, what it is, how produced, &c., 19, 153

 Flint, description and uses of, 53, 54
 ——, gun─flints, how made, 54

 Florence marble, description and use of, 115

 Fluat of lime, 119

 Fluats, 13

 Fluoric acid, what it is, 13
 —— ——, how to etch on glass by means of, 120
 —— ——, mode of obtaining, 120

 Fluor spar, description and properties of, 119
 —— ——, how manufactured, and the uses of, 119

 Flux, white, of what made, 137
 ——, black, 137

 Freestone, description and uses of, 233

 French chalk, description and uses of, 92

 Fuller’s earth, description and use of, 87

 Fulminating powder, 176

 Fulminating silver, extraordinary properties of, 182

 Fumigating of rooms, how effected, 133

 Fur in tea kettles, how formed there, 114


 G.

 Galena, what it is, 203

 Gangue, in mining, what it is, 4

 Garnet, precious, where found, how cut, and value of, 42, 43
 –– ——, how set, and uses of, 42
 ——, common, 43
 ——, Syrian and pyrope, 43

 Gas, what it is, 10

 Gas lights, history and uses of, 156
 —— ——, how produced, 156
 –– ——, how exhibited on a small scale, 156

 Gems, engraving, cutting, and value of, 21─23
 ——, imitations of, 22

 Giant’s causeway, account of, 95

 Gilding on iron or copper, how performed, 172
 —— in or─moulu, what it is, 172
 —— on silver, how performed, 172
 —— on the edges of tea─cups, 173
 —— wax, how made, and use of, 172
 ——, ancient mode of, 172
 ——, on wood, 172


 Glass, how made, 55
 ——, bottles, how made, 55
 ——, window and plate, how made, 55, 56
 ——, annealing of, the use of, 56
 ——, how to etch on, 120
 ——, Muscovy. See Mica.

 Glauber salt, description of, how obtained, and uses of, 123
 —— ——, pleasing experiment with, 134

 Glimmer. See Mica.

 Glucine, 16

 Gneiss, 226

 Gold, description and properties of, 167, 168
 ——, how obtained from mines in America and Europe, 168
 ——, found in Ireland and Scotland, 168, 169
 ——, mode of extracting from the ore, 169
 ——, value and uses of, 170
 ——, coinage or sterling gold; and gold of the new standard, 170
 ——, description of the stamps on gold plate, 170
 ——, how alloyed, 170
 ——, coinage gold of Portugal, America, France, Spain, Holland, and
    Morocco, 170
 ——, trinket and pale gold, how alloyed, 170
 ——, ductility and tenacity of, 170

 Gold leaf, how beaten, 171

 Gold wire, 173

 Gold thread and lace, what they are, 173

 Gold powder for painting, how made, 173
 ——, Dutch, how made, 187

 Gold─beaters’ skin, how made, and uses of, 171

 Granite, description and uses of, 225
 ——, various kinds of, 225

 Goulard, of what made, 207

 Grey─wacka, 232

 Grindstones, of what made, 234

 Gritstone, description and uses of, 233

 Gun─barrels, how browned, 141

 Gun─flints, how made, and how to choose, 54

 Gunpowder, how made, 137

 Gypsum. See Alabaster.
 ——, fibrous, description and uses of, 118


 H.

 Hair, pernicious effects of preparations to colour the, 181

 Heliotrope. See Bloodstone.

 Hone, or whetslate, description and use of, 80

 Hyacinth, description and uses of, 30

 Hydrogen, 19


 I.

 Inflammable air, 19

 Ink, indelible, for marking linen, how made, 181
 ——, sympathetic, how made, 222

 Instantaneous light, matches and bottles for procuring, how made, 145

 Iron, description and uses of, 190
 ——, mines, account of, 190
 ——, how extracted from the ore, 191
 ——, cast iron, what, and uses of, 191
 ——, wrought iron, how made, and uses of, 191
 ——, how preserved from rust, 193
 ——, native, account of extraordinary masses of, 197
 ——, magnetic, or loadstone, description and uses of, 197
 ——, white, what, 201

 Iron pyrites, description and uses of, 198
 ——, how to gild on, 172
 ——, sulphat of. See Vitriol, green.


 J.

 Jade, description and uses of, 88

 James’s powder, of what made, 217

 Jargoon, description and uses of, 29

 Jasper, description and uses of, 60
 ——, various kinds of, 61
 ——, agate. See Agate.

 Jet, description, properties, and uses of, 158
 ——, imitation of, 160


 K.

 Kaolin, what it is, and how made, 74

 Ketton stone, description and use of, 114


 L.

 Labrador felspar, description and uses of, 69

 Lapis lazuli. See Azure stone.

 Lapis ollaris, description and use of, 90

 Lazulite. See Azure stone.

 Lead, description of, 203
 ——, how extracted from the ore, 218
 ——, pig lead, what it is, 204
 ——, ancient and modern uses of, 204
 ——, injurious effects of leaden vessels, 204
 ——, alloys and oxides of, 205
 ——, silver, how obtained from, 178, 207
 ——, white, how manufactured, and uses of, 205
 ——, red or minium, how manufactured, and uses of, 206
 ——, sugar of, 207
 ——, how detected in wine, &c., 207
 ——, pleasing experiment with, 207

 Lead mines, account of, 203

 Lemnian earth, how obtained and use of, 86

 Lias, use of for multiplying drawings, 116

 Lime, 17; how burnt, and various uses of, 97
 —— water, how made, 98

 Lime carbonat of, 99

 Lime sulphat of, 117

 Lime fluat of, 119


 Limestone, description and uses of, 99
 ——, primitive, 228
 ——, transition, 232

 Litharge, how made and uses of, 206
 —— plaster, of what made, 206

 Loadstone, description of, where found, and uses of, 197

 Loam, description and uses of, 73

 Looking─glasses, process of silvering, 176

 Lunar caustic, what it is, and uses of, 181

 Lydian stone, description and uses of, 53


 M.

 Magnesia, how prepared and uses of, 125

 Malachite, description and uses of, 188

 Manganese, description of, how obtained, and uses of, 222

 Marble, description and uses of, 100
 ——, statuary, 102—105—109
 ——, Pentelic, Greek white, and Parian, 101
 ——, Carrara, Luni, and Verde antique, 102
 ——, Sienna, Brocatello, Mandelato, Verde di Prato, Lago Maggiore,
    Bretonico, and Campan, 103
 ——, Griotte, Marquese, Sarencolin, St. Beaume or Languedoc, Breccia of
    the Pyrenees, 104
 ——, white Spanish, Seville, Tortosa, Grenada, Spanish Breccia, 105
 ——, Lumachelli, Sicilian, Swiss, Portuguese, Russian, Asiatic marble of
    Tabriz, African, American, 106
 ——, Petworth, Purbeck, 107
 ——, Babbicombe, Derbyshire, Kendal, Mona, Tirie, 108
 ——, Assynt, Isle of Sky, Sutherland, Glen Tilt, 109
 ——, Blairgowrie, Glenavon, Ballichulish, Blairmachyldach, 110
 ——, mode of cutting and polishing, 111
 ——, black, 111
 ——, Florence, 115
 ——, Cottam, 116

 Marcasite. See Pyrites.

 Marking ink, for linen, &c. how made and used, 181

 Marl, description and uses of, 114

 Matrix, 4

 Meerschaum, how obtained, prepared, and used, 84

 Mercury, the ores of, 173
 ——, how extracted from the ore, 175
 ——, properties and uses of, 175, 176

 Mercury mines in India, description of, 175

 Metals, different states in which they are found, 165
 ——, how obtained and prepared for use, 165

 Meteoric stones, description of, 193
 —— ——, extraordinary instances of their falling from the air in 1492,
    1672, 1704, 1795, 1814, &c., 195
 —— ——, opinions of learned men respecting, 197
 —— ——, properties of, 194

 Mica, description of, how obtained, and uses of, 81

 Mica slate, or micaceous schistus, 227

 Millstones. See Burr Stone.
 ——, Peak, what formed of, 233
 ——, of granite, 225

 Millstone grit, description and uses of, 233

 Mineral green, of what made, 141

 Mineral oil. See Petroleum.

 Minerals, systematic arrangement of, 4

 Mineral tar, description and uses of, 148, 149

 Minium, how manufactured, and uses of, 206

 Mochoa stone, description and use of, 63
 —— ——, imitations of, how made, 63

 Mona marble. See Serpentine.

 Moonstone, description and use of, 70

 Mountains, comparative heights of the principal, 237

 Muriatic acid, 13

 Muriats, 13

 Muscovy glass. See Mica.

 Music plates, of what made, 217


 N.

 Naphtha, where found, uses and properties of, 146

 Natron, description of, how obtained and uses of, 128

 Nephrite. See Jade.

 Nickel, description and uses of, 208
 ——, oxide of, and for what used, 209

 Nitrats, 14

 Nitrat of silver, uses of, 181

 Nitre, description of, how and whence obtained, 136
 ——, how manufactured, and uses of, 136, 137

 Nitric acid. See Aqua fortis.

 Nova Mina topaz, 37


 O.

 Ochre, red, description and uses of, 199

 Obsidian, description and uses of, 66

 Oil, rancidity of, how corrected, 207

 Onyx, description and use of, 57

 Opal, description of, where found, use and value of, 63
 ——, imitations of, 64
 ——, Hydrophanous, singular quality, use, and value of, 64
 ——, Common, 65
 ——, Mother of pearl, and wood opal, 65, 66

 Orpiment, yellow, description and uses of, 214
 ——, red, 214

 Oxides, 11

 Oxygen, 10
 —— gas, 11


 P.

 Paint, white, how to prevent pernicious effects of, 205
 —— ——, made of oxide of zinc, 211

 Paviour’s flags, of what made, 234

 Paving stones, 225, 233

 Pearl─ash, what it is, and how prepared, 136
 —— white, of what made, and use of, 218

 Pebbles, 46

 Petrifactions. See Tufa.

 Petrifying springs, at Knaresborough and Matlock, 113

 Petroleum, description, properties, and uses of, 157

 Petunzè, 69

 Pewter, of what made, 202

 Phosphats, 12

 Phosphoric acid, 12─20

 Phosphorus, 19

 Pinchbeck, of what made, and use of, 187

 Pipe─clay, description and use of, 72

 Plaster of Paris, of what made, and use of, 118

 Plate glass, how made, 56

 Plating of copper, &c. how performed, 180

 Platina, description, properties, and uses of, 166, 167

 Pompey’s pillar, of what formed, 230

 Ponderous earth. See Barytes.

 Porcelain─clay, description and use of, 74
 ——, Chinese, French, and English porcelain, account of, 74
 ——, how manufactured, glazed, and painted, 74, 75
 ——, biscuit, how made, 47, 75

 Porphyry, description and uses of, 229

 Portland stone, description and use of, 114

 Potash, description of, how obtained, and use of, 135

 Potstone, description and use of, 90

 Pottery, how made, 73

 Powder blue, of what made, and use of, 222

 Prince’s metal, what it is, and for what used, 187

 Printer’s types, of what made, 205, 218

 Pumice, description and use of, 67

 Pyrites, description, properties, and uses of, 198, 199


 Q.

 Quartz, description, properties, and uses of, 44
 ——, rock, 231

 Queen’s ware pottery, of what made, 73

 Quick lime, how made, 98

 Quicksilver. See Mercury.


 R.

 Red chalk and Reddle, description and uses of, 199

 Realgar, description and uses of, 214

 Rocks, systematic arrangement of, 7, 224
 ——, primitive, description of, 224
 ——, secondary, 231
 ——, transition, 232
 ——, floetz or flat, 233
 ——, volcanic, 235

 Rock oil. See Naphtha.

 Roe stone. See Ketton stone.

 Roofing slate, description of, 76
 —— ——, how to choose, 77
 —— ——, Welsh and Westmoreland, 78
 —— ——, French, 76
 —— ——, various uses of, 77─80

 Rolling stones, of what made, 234

 Rotten stone, description and use of, 76

 Rouge, of what made, 84, 91

 Rubellite, valuable specimen of, 41

 Ruby, Oriental, description of, 31
 ——, whence imported, value, properties, and uses of, 31, 32
 ——, spinel, description, value, and uses of, 32
 ——, Balais, 32
 ——, false, 49

 Ruin marble. See Florence marble.


 S.

 Sal ammoniac, description of, how made, and uses of, 138, 139

 Salt, common, description and uses of, 129
 ——, mines in Poland, description of, 129
 ——, mines in Chester, 130
 ——, mountains of, in Spain, 130

 —— springs, 131

 Salt, how manufactured, 131
 ——, bay, 132
 ——, spirit of, how made, and uses of, 132

 Saltpetre. See Nitre.

 Sand, common, description and uses of, 52

 Sandstone, 234

 Sapphire, Oriental, description of, how cut and set, 30
 ——, properties, value, and use of, 30, 31
 ——, false, or water, 49

 Sardonyx, 57

 Scots pebbles, description and use of, 62

 Scythe─stones, how made, 234

 Sea froth. See Meerschaum.

 Sea water, description and properties of, 244
 —— ——, cause of its bitterness, and saltiness, 244
 —— ——, uses of, 245

 Serpentine, description and uses of, 89, 90

 Shell silver, how prepared, 181

 Shot, how made, 205

 Sienite, description and uses of, 230

 Silex, 15

 Siliceous earth, 15

 Silicium, 15

 Silver, description of, 177
 —— mines of Potosi and Norway, account of, 177, 178
 ——, found in Scotland, 178
 ——, extracted from lead, 178
 ——, how extracted from its ores, 178
 ——, value and uses of, and how alloyed, 179
 ——, marks or stamps on silver plate explained, 179
 ——, nitrat of, uses of, 181
 ——, fulminating, extraordinary properties of, 182
 ——, experiments with preparations of, 182
 ——, how to gild, 172

 Silver plate, how cleaned, 179
 ——, ductility of, 179

 Silver wire, 179

 Silvering of looking─glasses, process of, 176
 —— of metals, how performed, 186
 —— of paper and wood, 181

 Slate. See Roofing slate, and Writing slate.

 Slate pencils, how made, 78

 Slickenside, extraordinary properties of, 218

 Smalt, of what formed, and uses, 221
 ——, strewing, 221

 Smaragdus, 38

 Snowdon diamonds, what they are, 47

 Soap, how made, 127

 Soap, boiling, illustration of, 127
 ——, white, yellow, and soft, of what made, 128
 —— of glass, what it is, 223

 Soapstone. See Steatite.

 Soda, description and uses of, 126
 ——, carbonat of, 128
 ——, muriat of, 129
 ——, sulphat of, 133

 Solder, of what made, 205

 Soot, uses of, 156

 Spanish chalk, 84

 Spanish white, of what made, 100

 Spelter. See Zinc.

 Stalactites, description and uses of, 112

 Stalagmite, 112

 Steatite, description and uses of, 83

 Steel, how made, and uses of, 192, 193
 ——, Damascus, what, 192
 ——, cast, how made, 192
 ——, how to preserve from rust, 192

 Strontian, 17

 Stucco, of what made, 118

 Sulphur, 19; description of, and how manufactured, 143
 ——, uses and properties of, 143, 144
 ——, singular experiment with, 145

 Sulphuric acid, how prepared, properties and uses of, 145

 Sympathetic ink, how made and used, 222


 T.

 Table slates, how made, 78

 Talc, common, or Venetian, description and uses of, 91
 ——, indurated. See French chalk.

 Tamarind─tree, petrified. See Woodstone.

 Tartar, emetic, how prepared, 217

 Tea─cups, how to gild, 173

 Tea─urns, how browned, 141

 Thunderbolts. See Meteoric stones.

 Tiles, how made, 72

 Tin, description of, 200
 ——, alloys of, 202
 ——, block, and tin plate, what, and uses of, 200, 201
 ——, how extracted from the ore, 200

 Tin mines, and steam works, account of, 200

 Tin putty, how made, and uses of, 202

 Tin foil, how made, and uses of, 203

 Tin─glass. See Bismuth.

 Tincal. See Borax.

 Tinning of iron and copper, how performed, 201

 Tobacco pipes, how made, 73
 —— ——, Turkish, of what made, 84

 Topaz, description of, where found, and how obtained, 35, 36
 ——, value, uses, and properties of, 36
 ——, Oriental, 32
 ——, Brazilian, Saxon, Bohemian, blue, pink, white, or Nova Mina, 37

 Tourmaline, description and properties, and uses of, 40

 Trap, primitive, 228

 Tripoli, description and use of, 76

 Tufa, description and uses of, 113, 114

 Turkey stone, description and uses of, 81

 Turquoise, description of, how imported, and uses of, 189
 ——, spurious kind, how detected, 190

 Tutenag, of what made, and uses of, 210


 U.

 Ultramarine, how made, and uses of, 68

 Umber, description and use of, 199


 V.

 Verde antique marble, 102

 Verdigris, how made, and uses of, 186
 ——, distilled, what, and uses of, 186

 Vermilion, what it is, and how made, 177

 Vesuvian, description and use of, 43

 Vienna white, of what made, 100

 Vitriol,
 ——, blue, description of, how made and uses of, 140
 ——, green, or iron vitriol, 199
 ——, white, 141
 ——, spirit of. See Sulphuric acid.
 —— ——, pleasing experiment with, 142


 W.

 Water, uses and analysis of, 238, 239
 ——, rain, description and properties of, 240
 ——, ice and snow, description, properties, and uses of, 240
 ——, spring, river, and stagnant, 241─245
 ——, putrid, how to render sweet, 243
 ——, sea, 244
 ——, Malvern, 246
 ——, Bristol Hot─well, 246
 ——, Matlock and Buxton, 248
 ——, Bath, 249
 ——, Aix─la─Chapelle, or Aken, 250
 ——, Borset, 252
 ——, Vichy, 253
 ——, Carlsbad, 254
 ——, Sedlitz, 255
 ——, Epsom, 256
 ——, Seltzer, 256
 ——, Tunbridge, 257
 ——, Spa, 258
 ——, Pyrmont, 259
 ——, Cheltenham, 260
 ——, Brighton chalybeate, 261
 ——, Harrowgate, 262
 ——, Moffat, 264

 Whet─slate, description and uses of, 80

 Whiting, of what made, 100

 Window glass, how made, 55

 Wine, antimonial, how prepared, and use, 217
 ——, how to detect the adulteration of, 207

 Woodstone, description and uses of, 51

 Writing slates, how made, 78


 Y.

 Yttria, 16


 Z.

 Zaffre, what, how made, and uses of, 221

 Zinc, whence obtained, and how extracted from the ore, 209
 ——, uses and properties of, 210
 ——, oxide of, used as paint, 211
 ——, white, how prepared, 141

 Zircon, 29




                             END OF VOL. I.




      C. Baldwin, Printer,
    New Bridge─street, London.


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 ● Transcriber’s Notes:
    ○ The outline provide by the author (page 21) did not match the text
      in two places:
        ▪ “II. SOFT STONES” was changed to “ORDER II. SOFT STONES”.
        ▪ “ORDER II.—SALINE STONES” was changed to “ORDER III—SALINE
          STONES”.

    ○ Minor typographical errors were silently corrected.
    ○ Missing or obscured punctuation was silently corrected.
    ○ Inconsistent spelling and hyphenation were made consistent only
      when a predominant form was found in this book.
    ○ Text that was in italics is enclosed by underscores (_italics_);
      text that was bold by “equal” signs (=bold=).