Produced by Chris Curnow, Heike Leichsenring and the Online
Distributed Proofreading Team at http://www.pgdp.net (This
file was produced from images generously made available
by The Internet Archive)











  LEGAL CHEMISTRY.



  A GUIDE

  TO THE

  DETECTION OF POISONS,
  EXAMINATION OF TEA, STAINS, ETC.,



  AS APPLIED TO

  CHEMICAL JURISPRUDENCE.



  TRANSLATED WITH ADDITIONS FROM THE FRENCH OF


  A. NAQUET,

  _Professor to the Faculty of Medicine of Paris_.


  BY


  J. P. BATTERSHALL, Nat. Sc. D., F.C.S.



  _SECOND EDITION, REVISED, WITH ADDITIONS._

  NEW YORK:
  D. VAN NOSTRAND, PUBLISHER,
  23 MURRAY STREET AND 27 WARREN STREET.

  1884.




        COPYRIGHT.
  D. VAN NOSTRAND.
             1876.




Transcriber's Note:

Text originally marked up as bold is surrounded by *, text in italics by
_. Obvious printer errors have been corrected. A list of all other
changes can be found at the end of the document. In the Appendix of the
book, only the most obvious errors of punctuation were remedied.




PREFACE.


The importance of exact chemical analysis in a great variety of cases
which come before the courts is now fully recognized, and the
translation of this excellent little book on Legal Chemistry, by one of
the most distinguished French Chemists, will be appreciated by a large
class of American readers who are not able to consult the original.
While it is to be regretted that the author has not presented a much
more complete work, there is an advantage in the compact form of this
treatise which compensates, in some degree, for its brevity.

The translator has greatly increased the value of the book by a few
additions and his copious index, and especially by the lists of works
and memoirs which he has appended; and while he could have further
increased its value by additions from other authors, we recognize the
weight of the considerations which induced him to present it in the form
given to it by the author. Some chapters will have very little value in
this country at this day, but the translator could not, with propriety,
omit anything contained in the original.

  C. F. CHANDLER.




PREFACE TO THE SECOND EDITION.


The principal change to note in this edition of the LEGAL CHEMISTRY is
the addition of a chapter on Tea and its Adulteration. The general
interest at present evinced concerning this species of sophistication
appeared to call for a simple and concise method of examination which
would include the requisite tests without entering upon an exhaustive
treatment of the subject. The translator's practical experience in the
testing of tea at the United States Laboratory of this city has enabled
him to make a few suggestions in this regard which, he trusts, may be of
use to those interested in food-analysis. Numerous additions have also
been made to the bibliographical appendix.

  J. P. B.




CONTENTS.


                                                                    PAGE
  INTRODUCTION                                                         5

  METHODS OF DESTRUCTION OF THE ORGANIC SUBSTANCES

    By means of Nitric Acid                                            8

     "        " Sulphuric Acid                                         9

     "        " Nitrate of Potassa                                    10

     "        " Potassa and Nitrate of Lime                           12

     "        " Potassa and Nitric Acid                               12

     "        " Chlorate of Potassa                                   13

     "        " Chlorine                                              13

     "        " _Aqua Regia_                                          14

    Dialysis                                                          15

  DETECTION OF POISONS, THE PRESENCE OF WHICH IS SUSPECTED.

    Detection of Arsenic                                              17

      _Method used prior to Marsh's test_                             17

      _Marsh's test_                                                  21

      _Raspail's test_                                                29

      _Reinsch's test_                                                30

    Detection of Antimony                                             30

      _Flandin and Danger's apparatus_                                32

      _Naquet's apparatus_                                            34

    Detection of Mercury                                              36

      _Smithson's pile_                                               36

      _Flandin and Danger's apparatus_                                37

    Detection of Phosphorus                                           39

      _Orfila's method_                                               39

      _Mistcherlich's method_                                         40

      _Dusart's method, as modified by Blondlot_                      40

      _Fresenius and Neubauer's method_                               42

      _Detection of Phosphorus by means of bisulphide of carbon_      43

      _Detection of Phosphorous Acid_                                 45

      _Estimation of Phosphorus_                                      45

    Detection of Acids                                                46

      _Hydrochloric Acid_                                             46

      _Nitric_        "                                               47

      _Sulphuric Acid_                                                47

      _Phosphoric_  "                                                 48

      _Oxalic_      "                                                 49

      _Acetic_      "                                                 49

      _Hydrocyanic_ "                                                 50

    Detection of alkalies and alkaline earths                         52

    Detection of chlorine, bromine and iodine                         54

      _Chlorine and Bleaching Chlorides_                              54

      _Bromine_                                                       55

      _Iodine_                                                        56

    Detection of Metals                                               56

    Detection of alkaloids and some ill-defined organic substances    65

      _Stas's method_                                                 65

       "      " _as modified by Otto_                                 69

       "      "       "      " _Uslar and Erdman_                     70

      _Rodgers and Girdwood's method_                                 71

      _Prollius's method_                                             72

      _Graham and Hofman's method_                                    73

      _Application of Dialysis in the detection of Alkaloids_         74

      _Identification of the Alkaloid_                                74

      _Identification of Digitaline, Picrotoxine and Colchicine_      80

  METHOD TO BE EMPLOYED WHEN NO CLEW TO THE NATURE OF THE
  POISON PRESENT CAN BE OBTAINED                                      85

    Indicative tests                                                  86

    Determinative tests                                               94

  MISCELLANEOUS EXAMINATIONS                                          96

    Determination of the nature and color of the hair and beard       96

      _Determination of the color of the hair and beard_              96

      _Determination of the nature of the hair_                       99

    Examination of Fire-arms                                         100

      _The gun is provided with a flint-lock and was charged with
       ordinary powder_                                              100

      _The gun is not provided with a flint-lock_                    103

    Detection of human remains in the ashes of a fire-place          104

    Examination of writings                                          105

    Examination of writings, in cases where a sympathetic ink has
    been used                                                        110

    Falsification of coins and alloys                                112

    Examination of alimentary and pharmaceutical substances          114

      _Flour and Bread_                                              114

      _Fixed Oils_                                                   128

    _a Olive Oil intended for table use_                             128

    _b Olive Oil intended for manufacturing purposes_                130

    _c Hempseed Oil_                                                 130

      _Tea_                                                          130

      _Milk_                                                         137

      _Wine_                                                         142

      _Vinegar_                                                      147

      _Sulphate of Quinine_                                          148

    Examination of blood stains                                      150

    Examination of spermatic stains                                  158

  APPENDIX                                                           163

    Books of Toxicology, etc.                                        163

    Memoirs on Toxicology, etc.                                      168

  INDEX                                                              187




LEGAL CHEMISTRY.


The term Legal Chemistry is applied to that branch of the science which
has for its office the solution of problems proposed in the interest of
Justice. These most frequently relate to cases of poisoning. When the
subject of the symptoms or anatomical lesions produced by the reception
of a poison is under consideration, the services of a medical expert are
resorted to; but when the presence or absence of a poison in the organs
of a body, in the _egesta_ of an invalid or elsewhere is to be
demonstrated, recourse is had to the legal chemist. Investigations of
this character require great practice in manipulation, and, however well
the methods of analysis may be described in the works on the subject,
there would be great danger of committing errors were the examination
executed by an inexperienced person. The detection of poisons, although
perhaps the most important, is not the only subject that may come within
the province of the legal chemist; indeed, it would be somewhat
difficult to define, _a priori_, the multitude of questions that might
arise. In addition to cases of supposed poisoning, the following
researches are most often required:

1. The examination of fire-arms.

2. The analysis of ashes, in cases where the destruction of a human
body is suspected.

3. The detection of alteration of writings, and of falsification of
coins and precious alloys.

4. The analysis of alimentary substances.

5. The examination of stains produced by blood and by the spermatic
fluid.

Each of these researches justly demands a more extended consideration
than the limits of this work would permit. The several subjects will be
treated as briefly as possible, and at the same time, so as to convey an
exact idea of the methods employed, leaving to the expert the selection
of the particular one adapted to the case under investigation. We will
first mention the methods used in the search for toxical substances. The
poisons employed for criminal purposes are sometimes met with in a free
state, either in the stomach or intestines of the deceased person, or in
the bottles discovered in the room of the criminal or the victim. Under
these circumstances, it is only necessary to establish their identity by
means of their chemical properties, as directed in the general treatises
on chemistry, or by their botanical, or zoological character, in case a
vegetable or animal poison, such as cantharides, has been administered.
Examinations of this class are extremely simple, the analysis of the
substances found, confined to a few characteristic reactions, being a
matter of no great difficulty. We will not here dwell longer upon this
subject, inasmuch as the analytical methods used are identical with
those employed in more complicated cases, with the sole difference that,
instead of performing minute and laborious operations in order to
extract the poisons from the organs in which they are contained, with a
view of their subsequent identification, we proceed at once to establish
their identity. The directions given in regard to complicated
investigations apply, therefore, equally well to cases of a more simple
nature. The detection of a poison mixed with the organic substances
encountered in the stomach, or absorbed by, and intimately united with
the tissues of the various organs is more difficult. If, however, other
information than chemical can be obtained, indicating the poison
supposed to be present, and the presence or absence of this one poison
is the only thing to be determined, positive methods exist which admit
of a speedy solution of the question. When, on the other hand, the
chemical expert has not the advantage of extraneous information, but is
simply asked,--whether the case be one of poisoning?--nothing being
specified as to the nature of the poison used, the difficulty of his
task is greatly increased. Up to the present time, the works on
Toxicology have, it is true, given excellent special tests for the
detection of particular poisons; but none have contained a reliable
general method, which the chemical expert could use with the certainty
of omitting nothing. Impressed with this need, we proposed, in 1859, in
an inaugural dissertation then presented to the Faculty of Medicine, a
general method, which, after some slight modifications, is now
reproduced. The special methods which allow of the detection of various
individual poisons will, however, first be indicated. In cases where the
poison is mixed with organic matter, the latter must be removed as the
first step in the investigation, as otherwise the reactions
characteristic of the poison searched for would be obscured. When the
poison itself is an organic substance, this separation is effected by
processes modified according to the circumstances. If the detection or
isolation of a metallic poison is to be accomplished, the most simple
method consists in the destruction of the organic substances. The
various methods for effecting this decomposition will now be described.




I.

METHODS OF DESTRUCTION OF THE ORGANIC SUBSTANCES.


BY MEANS OF NITRIC ACID.

In order to destroy the organic matters by this process, a quantity of
nitric acid equal to one and a half times the weight of the substances
taken is heated in a porcelain evaporating dish, the amount of acid
being increased to four or six times that of the organic substances if
these comprise the brains or liver. As soon as the acid becomes warm,
the suspected organs, which have previously been cut into pieces, are
added in successive portions: the organs become rapidly disintegrated,
brownish-red vapors being evolved. When all is brought into solution,
the evaporation is completed and the carbonaceous residue obtained
separated from the dish and treated either with water, or with water
acidulated with nitric acid, according to the nature of the poison
supposed to be present.

Several objections to this method exist, the most serious of which is
based upon the fact that the carbonaceous residue, containing, as it
may, nitric acid, readily takes fire and may therefore be consumed, or
projected from the vessel. This objection is a grave one, and is not
always entirely removed by the continual stirring of the materials.
According to _M. Filhol_, the addition of 10 to 15 drops of sulphuric
acid to the nitric acid taken obviates the difficulty; not having
personally tested the question we cannot pronounce upon it. If it be the
case, this process is an advantageous one, as it is not limited in its
application, but can be used in the separation of all mineral poisons.


BY MEANS OF SULPHURIC ACID.

The organic matter to be decomposed is heated with about one-fifth of
its weight of concentrated sulphuric acid, the complete solution of the
materials being thus accomplished. The excess of acid is next removed by
heating until a spongy carbonaceous mass remains. The further treatment
of this residue depends upon the nature of the poison supposed to be
present. If the sulphate of the suspected poison is a soluble and stable
compound, the residue is directly treated with water; if, on the
contrary, there is reason to think that the sulphate has suffered
decomposition, the mass is taken up with dilute nitric acid; if,
finally, the presence of arsenic is suspected, the residue is moistened
with nitric acid, in order to convert this body into arsenic acid. The
acid is afterwards removed by evaporation, the well pulverized residue
boiled with distilled water, and the solution then filtered.

This method, when applied in the detection of arsenic, is objectionable
in that the carbonaceous residue, in contact with sulphuric acid, almost
invariably contains sulphurous acid, detected by means of permanganate
of potassa. This acid, being reduced in the presence of hydrogen, would
cause the formation of insoluble sulphide of arsenic, and in this way
prevent the detection of small amounts of arsenic by the use of Marsh's
apparatus. _M. Gaultier de Claubry_, indeed, states that he has not been
able to detect the presence of sulphurous acid in the carbonaceous
residue; but one affirmative result would, in this case, outweigh twenty
negative experiments. A further objection to this process consists in
the fact that the materials to be destroyed almost always contain
chlorides, which, in presence of sulphuric acid and an arsenical
compound, might determine the formation of chloride of arsenic, a
volatile body, and therefore one easily lost. This difficulty is
doubtless of a less serious nature than the preceding, as the operation
can be performed in a closed vessel provided with a receiver which
admits of the condensation of the evolved vapors; but even then the
process would be prolonged. The above method is still again
objectionable on account of its too limited application, it being
serviceable almost exclusively in cases where the poisoning has been
caused by arsenic, for, if applied in other instances, a subsequent
treatment would be necessary in order to redissolve the metal separated
from its decomposed sulphate.


BY MEANS OF NITRATE OF POTASSA.

This method was formerly executed as follows: Nitrate of potassa was
fused in a crucible, and the substances to be destroyed added in small
portions to the fused mass. The organic matter soon acquired a pure
white color; owing, however, to the imperfect admixture of the organic
matter with the salt used for its decomposition, it was necessary to
take a large excess of the latter.

The following process, suggested by _M. Orfila_, remedies this
inconvenience: The organs are placed in an evaporating dish, together
with one tenth of their weight of caustic potassa, and a quantity of
water varying with the weight of the substances taken. An amount of
nitrate of potassa equal to twice the weight of the organic matter is
next added, and the mixture evaporated to dryness. The residue is then
thrown by fragments into a Hessian crucible heated to redness, the
portions first taken being allowed to become perfectly white before more
is added.

Whichever process has been employed, the fused mass is decanted into a
porcelain crucible, which has previously been heated in order to avoid
danger of breakage. The portion remaining in the vessel is taken up by
boiling with a small quantity of distilled water, and the solution so
obtained likewise added to the crucible. The mass is then heated with
sulphuric acid until all nitrous fumes are expelled, as these could give
rise to an explosion, when, in the search for arsenic, the substance is
introduced into Marsh's apparatus. As soon as the nitric acid is
completely expelled, the liquid is allowed to cool; the greater portion
of the sulphate of potassa formed now separating out in crystals. The
fluid is next filtered and the crystalline salt remaining on the filter,
washed, at first with a little distilled water, then with absolute
alcohol, which is subsequently removed from the filtrate by boiling.
This method is scarcely applicable otherwise than in the detection of
arsenic, as in other instances the presence of a large amount of
sulphate of potassa would be liable to affect the nicety of the
reactions afterwards used. Its application, even in the search for
arsenic, is not to be strongly recommended; on the contrary, the
separation of the potassa salt by filtration is indispensable, as
otherwise a double salt of zinc and potassium, which might be formed,
being deposited upon the zinc used in Marsh's apparatus, would prevent
the disengagement of hydrogen, and every chemist is too well aware of
the difficulty of thoroughly washing a precipitate, not to fear the
possible loss of arsenic by this operation.


BY MEANS OF POTASSA AND NITRATE OF LIME.

In this method the organic materials are heated with water and 10 to 15
per cent. of caustic potassa. As soon as disintegration is completed,
nitrate of lime is added, and the mixture evaporated to dryness. A
glowing coal is then placed upon the carbonaceous residue obtained: the
mass, undergoing combustion, leaves a perfectly white residue. This
residue dissolves in hydrochloric acid to a clear fluid which is then
examined for poisons.

The above process possesses the undeniable advantage of completely
destroying the organic substances, at the same time avoiding the
introduction of sulphate of potassa, the presence of which impairs the
usefulness of the preceding method; but it necessitates the presence of
numerous foreign bodies in the substance to be analysed, and this should
be avoided. The _absolute purity_ of reagents is not always to be
attained, and the results of an analysis are the more certain, in
proportion as they are less numerous and more easily purified.


BY MEANS OF POTASSA AND NITRIC ACID.

It has been proposed, instead of using nitrate of lime, to dissolve the
organic matter in potassa and then saturate the fluid with nitric acid.
This method is evidently more complicated than the simple treatment with
nitrate of potassa, and possesses, moreover, no advantages over the
latter process.


BY MEANS OF CHLORATE OF POTASSA.

The organic materials are treated with an equal weight of pure
hydrochloric acid, and water added, so as to form a clear pulp. This
being accomplished, two grammes of chlorate of potassa are added to the
mixture at intervals of about five minutes. The fluid is next filtered,
and the insoluble residue remaining on the filter washed until the
wash-water ceases to exhibit an acid reaction. The filtrate is then
evaporated, an aqueous solution of sulphurous acid added, until the odor
of this reagent remains distinctly perceptible, and the excess of the
acid removed by boiling the solution for about an hour. The fluid is now
adapted to further examination for arsenic, or other metallic poisons.

This method is one of the best in use, both chlorate of potassa and
hydrochloric acid being reagents easily procured in a state of great
purity; their use, however, is liable to the objection that they convert
silver and lead into insoluble chlorides.


BY MEANS OF CHLORINE.

_M. Jacquelain_ suggests, in the search for arsenic, the decomposition
of the organic matters by means of a current of chlorine, and recommends
the following process: The organic substances are bruised in a mortar
and then macerated with water. The fluid so obtained, in which the
organic matter is held suspended, is next placed in a flask into which a
current of chlorine is passed until all the organic matter is deposited
in colorless flakes on the bottom of the vessel. The flask is then well
closed and allowed to stand for 24 hours, when the odor of the gas
should still be perceptible. The fluid is now filtered, the filtrate
concentrated by heating in a vessel which permits of the preservation of
the volatile chloride of arsenic possibly present, and then examined for
poisons.

This process fails to possess the degree of generality desirable, and
presents the disadvantage of requiring considerable time for its
execution.


BY MEANS OF AQUA REGIA.

This method is exceedingly simple: _Aqua regia_ (a mixture of two parts
of hydrochloric and one part of nitric acids) is placed in a tubular
retort provided with a receiver, and the organic materials, which have
previously been cut into small pieces, added; the reaction commences
immediately; if it is not sufficiently active, it is accelerated by a
gentle heat: lively effervescence now occurs, and the destruction of all
non-oleaginous substances is soon accomplished. The latter substances
alone are not immediately decomposed by _aqua regia_, which attacks them
only after prolonged action. As soon as the operation is concluded, the
apparatus is removed from the fire and taken apart. The fluid condensed
in the receiver is added to that remaining in the retort, and the whole
thoroughly cooled in an open dish. The fatty matters now form a solid
crust upon the surface of the fluid, which is removed and washed with
distilled water, and, the washings being added to the rest of the
solution, the latter is directly examined for metallic poisons. It is
recommended by _Gaultier de Claubry_, in cases where the detection of
arsenic is desired, to saturate and afterwards boil the suspected fluid
with sulphuric acid, in order to remove the nitric and hydrochloric
acids present.


DIALYSIS.

The application of the dialytic method was first proposed by _Graham_.
By its use we are enabled to distinguish between two large classes of
bodies, viz., _colloids_ and _crystalloids_. Albumen, gelatine, and
analogous substances are typical of colloid bodies; crystalloid
substances, on the other hand, are those that are capable of
crystallization, either directly or in their compounds, or, in case they
are fluids, would possess this property when brought to the solid state.
Graham discovered that when an aqueous solution containing a mixture of
colloid and crystalloid substances is placed in a vessel having for its
bottom a piece of parchment or animal membrane, and this is immersed in
a larger vessel filled with water, all of the crystalloids contained in
the first vessel transverse the porous membrane and are to be found in
the larger vessel, the colloid bodies being retained above the membrane.
The organic matter to be eliminated in toxicological researches being
colloids, and the poisons usually employed being crystalloids, the value
of dialysis as a method of separation is evident. The process is
executed as follows:

  [Illustration: Fig. 1.]

A wooden,--or better, a gutta-percha--cylinder (Fig. 1), 5 cubic
centimetres in height and from 20 to 25 c. c. in diameter, is employed.
A piece of moistened parchment is securely attached to one of the
openings of the cylinder, which, upon drying, shrinks and completely
closes the aperture. If its continuity becomes impaired, the pores of
the membrane should be covered with the white of an egg which is
subsequently coagulated by the application of heat. The organs
previously cut into small pieces, or the materials found in the
alimentary canal, etc., after having been allowed to digest for 24 hours
in water at 32°[A]--or, in dilute acids, if the presence of an alkaloid
is suspected,--are then placed in the upper vessel, which is termed the
dialyser. The whole should form a layer not over 2 cubic centimetres in
height. The dialyser is next placed in the larger vessel filled with
distilled water. In about 24 hours three-quarters of the crystalloid
substances present will have passed into the lower vessel. The solution
is then evaporated over a water-bath, and submitted to analysis. The
portion remaining in the dialyser is decomposed by one of the methods
previously described, in order to effect the detection of any poisonous
substances possibly present. Instead of the above apparatus, the one
represented in Fig. 2 can be employed. The fluid under examination is
placed in a bell-shaped jar, open at the top and closed below with a
piece of parchment, which is then suspended in the centre of a larger
vessel containing water. In other respects the operation is performed in
the same manner as with the apparatus represented in Fig. 1.

  [Illustration: Fig. 2.]

  [A] The degrees of temperature given in the text refer to the
  centigrade Thermometer; their equivalents on the Fahrenheit scale can
  be obtained by means of the formula:

          9/5 C° + 32 = F°.

  --_Trans._




II.

DETECTION OF POISONS, THE PRESENCE OF WHICH IS SUSPECTED.


DETECTION OF ARSENIC.

It is frequently required, in chemical jurisprudence, to institute a
search for arsenic in the remains of a deceased person, whose death is
supposed to have been caused by the reception of a poison. Under these
circumstances the poison is mixed with a mass of substances which would
obscure its characteristic properties, and it becomes necessary, in
order to accomplish its identification, to isolate it, and then, by
decisive reactions, determine its character. Three methods exist which
permit of this result; they are:

1st. The method used prior to Marsh's test.

2nd. Marsh's test.

3rd. A method more recent than Marsh's, proposed by _M. Raspail_.


METHOD USED PRIOR TO MARSH'S TEST.

The materials supposed to contain arsenic are boiled in water which
has been rendered strongly alkaline by the addition of pure potassa. The
fluid is then filtered, an excess of hydrochloric acid added, and a
current of sulphuretted hydrogen conducted through it. If arsenic be
present in the suspected fluid, it is soon precipitated as a yellow
sulphide. In dilute solutions the formation of the precipitate fails to
take place immediately, and only a yellow coloration of the fluid is
perceptible; upon slightly boiling the solution, however, the
precipitation of the sulphide is soon induced. The precipitate is
collected on a filter, well washed with boiling water, and then removed,
if present in a quantity sufficient to admit of this operation. It is
next dissolved in ammonia,[B] and the solution so obtained subsequently
evaporated to dryness on a watch-glass. The residue of sulphide of
arsenic is placed in a tube closed at one end containing nitrate of
potassa in a state of fusion: it is decomposed by this treatment into a
mixture of sulphate and arsenate of potassa, the reaction being
completed in about fifteen minutes. The mixture is now dissolved in
water, and lime water added to the solution: a precipitate of arsenate
of lime is formed, which is separated from the fluid by filtration,
dried, mixed with charcoal, and introduced into a second tube. A few
pieces of charcoal are then placed in the tube adjoining the mixture and
exposed to a red heat, the part of the tube containing the arsenical
compound being also heated. By this operation the arsenic acid is
reduced to arsenic, which is deposited upon the cold portion of the tube
in the form of a metallic mirror. This mirror is then identified by
subsequent reactions. The method just described is no longer in use,
although the precipitation of the arsenic by sulphuretted hydrogen is
still often resorted to in its separation from the other metals with
which it may be mixed. The destruction of the organic substances is,
however, accomplished by means of chlorate of potassa and hydrochloric
acid. To insure the complete precipitation of the arsenic, it is
advisable to conduct sulphuretted hydrogen through the solution, at a
temperature of 70° for twelve hours, and then allow the fluid to remain
in a moderately warm place, until the odor of the gas is no longer
perceptible, the vessel being simply covered with a piece of paper. The
precipitate is next freed from the other metals possibly present, as
directed in the general method of analysis, collected on a filter, and
dissolved in ammonia. The ammoniacal solution is evaporated on a watch
crystal, as previously described, and the residuary sulphide reduced to
metallic arsenic. This reduction is effected by a process somewhat
different from the one previously mentioned: the residue is fused, in a
current of carbonic acid gas, with a mixture of carbonate of soda and
cyanide of potassium. The apparatus employed is represented in Fig. 3:
_a_, is an apparatus producing a constant supply of carbonic acid. Upon
opening Mohr's clamp, _g_, the gas passes into the flask _h_, which
contains sulphuric acid; it is then conducted, by means of the tube _i_,
into the reduction tube _k_, which has an interior diameter of 8 mm.
This tube is represented, in half size, in Fig 4.

  [B] The sulphur, usually accompanying the precipitate of sulphide of
  arsenic, is insoluble in ammonia.--_Trans._

  [Illustration: Fig. 3.]

  [Illustration: Fig. 4.]

The reduction is performed as follows: The sulphide of arsenic is
ground in a small mortar, previously warmed, together with 12 parts of a
mixture consisting of 3 parts of carbonate of soda and 1 part of cyanide
of potassium, both salts being perfectly dry. The powder thus obtained
is placed upon a piece of paper rolled in the form of a gutter, and
introduced into the reduction tube. The latter is then turned half round
its axis, so as to cause the mixture to fall in _de_ without soiling the
other parts of the tube. The paper is now withdrawn and the apparatus
mounted. Upon opening the clamp _g_, and strongly heating the mixture by
either the flame of a gas or an alcohol lamp, a mirror-like ring of
metallic arsenic is deposited at _h_, if this poison be present in the
substances under examination. When the coating is too minute to permit
of perfect identification, it should be driven by heat to a thinner part
of the tube; in this way it is rendered easily visible, being condensed
upon a smaller space.

The above process possesses the advantage of not allowing arsenic to be
confounded with any other body; it also permits of a quantitative
estimation of the poison present. For this purpose, it is only necessary
to previously weigh the watch-crystal, upon which the ammoniacal
solution of sulphide of arsenic was evaporated, and to determine its
increased weight after the evaporation; the difference of the two
weighings multiplied by 0.8049, gives the corresponding weight of
arsenious acid, and by 0.6098, the weight of the corresponding amount of
metallic arsenic.


MARSH'S TEST.

Marsh's test is based upon the reduction of arsenious and arsenic acids
by nascent hydrogen, and the subsequent transformation of these bodies
into water and arsenetted hydrogen, a compound from which the arsenic
can be readily isolated. When pure hydrogen is generated in a flask
having two openings, one of which is provided with a perforated cork
through which a safety-tube passes, the other with a tube bent at a
right angle and drawn out to a small point at the free extremity, the
evolved gas, if ignited, burns with a pale non-luminous flame. The air
should be completely expelled from the apparatus before igniting the
gas. Upon bringing a cold porcelain saucer in contact with the point of
the flame, only water is formed. If, however, a small quantity of a
solution containing arsenious or arsenic acids is introduced into the
apparatus by means of the safety-tube, arsenetted hydrogen is produced.
This gas burns with a bright flame, yielding fumes of arsenious acid. In
case a large amount of the poison is present, it can be recognized by
the appearance of the flame, and by inclining a glass tube towards it
upon which a portion of the arsenious acid becomes deposited. These
indications are, however, not distinguishable in presence of only a
small amount of arsenic, and the following distinctive properties of the
gas should be verified:

1st. At an elevated temperature it is decomposed into its two
constituent elements.

  [Illustration: Fig. 5.]

  [Illustration: Fig. 6.]

2nd. The combustibility of the constituents differs: the arsenic being
less combustible than the hydrogen, begins to burn only after the
complete consumption of the latter body has taken place. For this reason
the flame (Fig. 5) is composed of a dark portion _O_ and a luminous
portion _I_, which surrounds the first. The maximum temperature exists
in _O_ at the point of union of the two parts of the flame. Owing to an
insufficient supply of oxygen, the complete combustion of the arsenic in
this part of the flame is impossible, and if it be intersected by the
cold surface _A B_, that body is deposited as a brown spot, possessing a
metallic lustre. The metallic deposit originates, therefore, from the
decomposition of the arsenetted hydrogen by heat and from its incomplete
combustion. If the spot is not large, it fails to exhibit a metallic
lustre; an experienced chemist, however, will be able to identify it by
the aid of proper tests. Spots are sometimes obtained when the substance
under examination does not contain the least trace of arsenic. These may
be caused by antimony or by a portion of the zinc salt in the generating
flask being carried over by the gaseous current. This difficulty is
remedied by giving the apparatus the form represented in Fig. 6. _A_ is
the flask in which the gas is generated. The delivery-tube _I_ connects
with a second tube _H_, filled with asbestus or cotton; this is united
by means of a cork with a third tube _C_, made of Bohemian glass. The
latter tube is quite long, and terminates in a jet at its free end,
enclosed in tin-foil;[C] it passes through the sheet-iron furnace _R_,
supported upon _G_. The screen _D_ protects the portion _D E_ of the
tube _C_ from the heat. The gas disengaged is ignited at _E_ and the
porcelain dish _P_ is held by the hand in contact with the flame. The
apparatus being mounted, zinc, water and some sulphuric acid are placed
in the generating flask,[D] and the solution containing arsenious acid
added: the evolution of gas commences immediately. The tube _H_ serves
to retain any liquids that may be held suspended. The gas then passes
through the part _C D_ of the tube _C_, which is heated by placing a few
live coals upon the furnace _R_. The greater portion of the arsenetted
hydrogen is decomposed here, and is deposited on the cold part of the
tube, in a mirror-like ring. The small quantity of gas that escapes
decomposition, if ignited at _E_, produces a metallic spot on the dish
_P_. In order to determine that the spots are due to the presence of
arsenic, and not produced by antimony, the following tests should be
applied:

  [C] The fusing of the point of the tube is also prevented by
  platinizing it. The tube is drawn out, its end roughened by filing,
  and then immersed in solution of bichloride of platinum, so that a
  drop or two of the fluid adheres. The point, upon heating, now
  acquires a fine metallic lustre, and by repeating the operation a few
  times a good coating of platinum is produced both on the exterior and
  interior of the tube.--_Trans._

  [D] The addition of a few drops of solution of bichloride of platinum
  to the mixture of zinc, water and sulphuric acid is
  advisable.--_Trans._

1. The color of the spots is distinctive: arsenical spots are brown and
exhibit a metallic lustre, whereas those originating from antimony
possess a black color, especially near their border. This difference is,
however, not perceptible when the deposits have a large surface.

2. If the mirror be arsenical, it is readily volatilized from one part
of the tube to another, when the latter is heated, and a current of
hydrogen, or carbonic acid gas made to pass through it. Spots that are
due to the presence of antimony are much less volatile.

3. If the tube is held in an inclined position so that a current of air
traverses it, and the part containing the arsenical mirror heated, the
arsenic oxidizes and arsenious acid is sublimed and deposited higher up
in the tube in the form of a ring, which exhibits octahedral crystals
when examined with a magnifying glass. This ring should be further
tested as follows:

_a._ If it is dissolved in a drop of hydrochloric acid and a solution
of sulphuretted hydrogen added, a yellow precipitate of sulphide of
arsenic is formed. This compound is soluble in ammonia and in alkaline
sulphides, but insoluble in hydrochloric acid.

_b._ If the ring is dissolved in pure water and an ammoniacal solution
of sulphate of copper added, a beautiful green precipitate ("_Scheele's
green_"), consisting of arsenite of copper, is produced.

4. When produced by arsenic the spots are soluble in nitric acid, and
upon evaporating the solution so obtained to dryness, a residue of
arsenic acid, which is easily soluble in water, remains. If an
ammoniacal solution of nitrate of silver is added to the aqueous
solution of the residue, a brick-red precipitate is produced. Spots
consisting of antimony give, when treated with nitric acid, a residue of
an intermediate oxide, insoluble in water.

5. Upon treating the spots with a drop of solution of sulphide of
ammonium, the sulphide of the metal present is formed: if sulphide of
arsenic is produced its properties, as enumerated above, can be
recognized. It may be added that the sulphide of antimony formed is
soluble in hydrochloric acid, and possesses an orange red color, whereas
sulphide of arsenic is yellow.

6. When spots originating from arsenic are treated with a solution of
hypochlorite of soda (prepared by passing chlorine into solution of
carbonate of soda), they are immediately dissolved; if, on the other
hand, they are produced by antimony, they remain unaltered by this
treatment.

Such are the properties exhibited by soluble compounds of arsenic when
treated by Marsh's process; the following precautions are, however,
necessary when this test is made use of in medico-legal examinations.

1. If small white gritty particles, resembling arsenious acid, are
discovered in the stomach or intestines, they are directly introduced
into Marsh's apparatus. When this is not the case, the destruction of
the organic matter is indispensable even though, instead of the organs
themselves, the contents of the alimentary canal are taken. In the
latter instance, the solids are separated from the fluids present by
filtration, the solution evaporated to dryness and the residue united
with the solid portion; the organic matter is then destroyed by one of
the methods previously described. In the special case of arsenic, the
separation of the poison from the accompanying organic materials can be
accomplished by a process not yet mentioned which may prove to be of
service. The suspected substances are distilled with common salt and
concentrated sulphuric acid. By this operation the arsenic is converted
into a volatile chloride which distils over. The poison is isolated by
treating this compound with water, by which it is decomposed into
hydrochloric and arsenious acids. We must give preference, however, to
the method by means of chlorate of potassa and hydrochloric acid.

2. The solution having been obtained in a condition suitable for
examination, the air is completely expelled from the apparatus by
allowing the gas to evolve for some time, and the suspected fluid then
introduced into the generating flask. Danger of explosion would be
incurred were the gas ignited when mixed with air.[E]

  [E] The effervescence of the mixture is prevented by _slowly_ adding
  the arsenical solution to the generating flask. In order to avoid loss
  of arsenetted hydrogen, the cold dish should be directly applied to
  the flame even before the introduction of the suspected solution, and
  its position changed at short intervals, so as to allow the deposit to
  be formed on different parts.-_Trans._

3. It is indispensable, in applying this test, to have a second
apparatus in which only the reagents necessary to generate hydrogen are
placed: in this way, if no spots are now produced by the use of the
second apparatus, it is certain that those obtained when the first
apparatus is employed do not originate from impurities present in the
reagents used.

It has come under the author's observation, however, that a sheet of
zinc sometimes contains arsenic in one part and not in another; in fact,
the shavings of this metal, as purchased for laboratory use, are often
taken from lots previously collected, and may therefore have been
prepared from several different sheets. If this be the case, it is
supposable that the zinc used in the second apparatus may be free from
arsenic, whereas the metal with which the suspected solution is brought
in contact may contain this poison; serious danger would then exist of
finding indications of the presence of arsenic in materials that did not
originally contain a trace of the metal. In order to obviate this
important objection, which might possibly place a human life in
jeopardy, we propose the following modifications: Pure mercury is
distilled and its absolute purity established. As the metal is a fluid
and is therefore homogeneous, it is evident if one portion be found
pure, the entire mass is so. Sodium is then fused under oil of naphtha,
in order to cause the complete admixture of its particles, and the
purity of the fused metal in regard to arsenic tested. An amalgam is
next prepared by uniting the mercury and sodium. This is eminently
adapted to toxicological investigations: in order to generate a supply
of very pure hydrogen, it is only necessary to place the amalgam in
water kept slightly acid by the addition of a few drops of sulphuric
acid, by means of which the disengagement of gas is rendered more
energetic.[F]

  [F] Owing to the impurities often occurring in zinc, the use of
  distilled magnesium in Marsh's apparatus has also been suggested. This
  metal is now to be obtained in a state of great purity; it is,
  however, sometimes contaminated with silicium, which body likewise
  gives rise to a metallic deposit, but one that is readily
  distinguished from arsenical spots by its insolubility in nitric acid,
  _aqua regia_, and in hypochlorite of soda. The presence of magnesium
  causes the precipitation of the non-volatile metals possibly contained
  in the fluid tested for arsenic.--_Trans._

It should be borne in mind that the solution introduced into Marsh's
apparatus must not contain organic substances, and that, in case their
destruction has been accomplished by means of nitric acid all traces of
this compound are to be removed. The sulphuric acid used should also be
completely freed from nitrous vapors. According to _M. Blondeau_,
nascent hydrogen in the presence of nitrous compounds converts the acids
of arsenic not into arsenetted hydrogen (As H{3}), but into the _solid_
arsenide of hydrogen (As{4} H{2}). This latter compound, upon which pure
nascent hydrogen has no effect, is transformed into gaseous arsenetted
hydrogen by the simultaneous action of nascent hydrogen and organic
substances. These facts are of the greatest importance, for they might
possibly cause a loss of arsenic when it is present, as well as
determine its discovery when it is absent.

The first case is supposable: should traces of nitric acid remain in
the solution, the arsenic would be transformed into solid arsenide of
hydrogen and its detection rendered impossible. The second case may also
occur: if the zinc placed in the apparatus contains arsenic, and the
sulphuric acid used contains nitrous compounds, the evolved gas will
fail to exhibit any evidence of the presence of arsenic, owing to the
formation of the solid arsenide of hydrogen. Upon adding the suspected
solution, which, perchance, may still contain organic substances, this
arsenide is converted into arsenetted hydrogen, and the presence of
arsenic will be detected, although the solution under examination was
originally free from this metal.


RASPAIL'S METHOD.

M. Raspail suggests the following method for detecting arsenic: The
surface of a brass plate is rasped by filing. In this condition the
plate may be regarded as an innumerable quantity of voltaic elements,
formed by the juxtaposition of the molecules of zinc and copper. The
suspected materials are boiled with caustic potassa, the solution
filtered, a drop of the filtrate placed upon the brass plate, and a drop
of chlorine water added. If the plate is then allowed to stand for a
moment and the substance under examination contains arsenic, a
mirror-like spot is soon deposited upon its surface. In order to avoid
confounding this deposit with those produced by other metals, the
substitution of granulated brass for the plate is in some cases
advisable. The granulated metal is dipped successively in the suspected
solution and in chlorine water. The granules retain a small quantity of
the solutions and, owing to the action of the chlorine water, become
covered with metallic spots, if arsenic be present. They are then dried,
placed in a tube closed at one end, and exposed to the heat of an
alcohol lamp. In case the spots are arsenical, the metal volatilizes and
condenses in a ring upon the cold part of the tube, which is submitted
to the tests previously described.

This method can hardly be of great service, inasmuch as it extracts the
poison from but a very small portion of the solution containing it: we
have not, however, personally tested its merits.[G]

  [G] The omission in the text of Reinsch's test should be supplied.
  This test is based upon the fact that when solutions of arsenious acid
  or an arsenide are acidulated with hydrochloric acid and boiled with
  metallic copper, the latter becomes covered with a film consisting
  largely of metallic arsenic: it is extensively employed in
  chemico-legal examinations. The materials to be examined are
  completely disintegrated by boiling with hydrochloric acid, and the
  fluid filtered. Some pure copper gauze or foil, having a polished
  surface, is then immersed in the boiling solution, and notice taken of
  the formation of a grey deposit. If a coating be formed, fresh pieces
  of the metal are added, so long as they become affected. The copper is
  then withdrawn from the solution, thoroughly washed with water, and
  dried, either by means of the water-bath or by pressing between
  bibulous paper. It is next introduced into a dry tube, and heated over
  a spirit lamp. The arsenic present volatilizes and is oxidized to
  arsenious acid which forms a deposit, consisting of octahedral
  crystals, on the cold part of the tubes. These are subsequently tested
  by means of the reactions distinctive of arsenious acid. It need
  hardly be added that the absolute purity of both the hydrochloric acid
  and of the copper is to be carefully established. The deposit obtained
  in the above operation was formerly regarded as pure arsenic, but it
  has been proved to be an alloy consisting of 32 per cent. arsenic, and
  68 per cent. copper. Reinsch's test possesses the advantage of
  requiring but little time for its execution, of being applicable to
  complex organic mixtures, and of effecting the detection of a very
  minute trace of the poison.--_Trans._


DETECTION OF ANTIMONY.

Strictly speaking the salts of antimony are more therapeutic than
poisonous in their action. In fact they usually act as emetics and,
under certain circumstances, may be taken in large doses without
incurring serious results. There are instances, however, in which their
action is truly toxical, and it becomes necessary to effect their
detection in the organs of a body. It should be remarked that these
salts, if absorbed, remain by a kind of predilection in the liver and
spleen. A special examination of these organs should therefore be
instituted, particularly if the fluids of the alimentary canal are not
at hand, which is frequently the case when some time has elapsed before
the investigation is undertaken.

The remarks made in the preceding article concerning the distinctive
properties of arsenic and antimony need not be repeated here. The search
for antimony is likewise executed by aid of Marsh's apparatus. We will
confine ourselves to a description of a modification to this apparatus
proposed by _MM. Flandin_ and _Danger_, and employed in the separation
of antimony and arsenic, when a mixture of these metals is under
examination. Another process, by means of which we arrive at the same
result with greater certainty and by the use of a less expensive
apparatus, will then be mentioned. We will, however, first indicate the
preferable method of destruction of the organic substances.

Were the decomposition performed by means of sulphuric acid, sulphate of
antimony, a slightly soluble salt and one not well adapted to the
subsequent treatment with nascent hydrogen, would be formed. In order to
obtain the metal in a soluble state, the formation of a double tartrate
of antimony and soda is desirable. This may be accomplished in the
following manner:

1. A cold mixture of nitrate of soda, sulphuric acid, and the suspected
materials is prepared in the proportion of 25 grammes of the nitrate to
39 grammes of the acid, and 100 grammes of the substance under
examination. This mixture is heated and evaporated to dryness, and the
decomposition of the organic matter completed in the usual manner. The
carbonaceous residue obtained is pulverized, and then boiled with a
solution of tartaric acid. By this treatment the antimonate of soda
present is converted into a double tartrate of antimony and soda, which
is easily soluble in water. The solution is filtered and then introduced
into Marsh's apparatus.

2. Another method consists in heating the substances under examination
with one half of their weight of hydrochloric acid for six hours on a
sand-bath, avoiding boiling. The temperature is then increased until the
liquid is in a state of ebullition, and 15 to 20 grammes of chlorate of
potassa, for every 100 grammes of the suspected matter taken, added in
successive portions, so that a quarter of an hour is required for the
operation. The liquid is next filtered, and the resinous matter
remaining on the filter well washed with distilled water; the washings
being added to the principal solution. A strip of polished tin is then
immersed in the liquid: in presence of a large amount of antimony the
tin becomes covered with a black incrustation: if but a minute quantity
of the metal is contained, only a few blackish spots are perceptible.
After the tin has remained immersed for 24 hours, it is withdrawn and
placed in a flask together with an amount of hydrochloric acid
sufficient for its solution in the cold. If, after several hours,
blackish particles are still observed floating in the liquid, they can
be dissolved in a few drops of _aqua regia_. The solution may then be
directly introduced into Marsh's apparatus.


APPARATUS PROPOSED BY FLANDIN AND DANGER.

  [Illustration: Fig. 7.]

This apparatus consists of a wide necked jar _A_ (Fig. 7) for the
generation of the gas, the mouth of which is closed with a cork having
two openings. The safety tube _S_, which is funnel-shaped at its upper
extremity and has its lower end drawn out to a point, passes through one
of these apertures; the other opening contains the small delivery tube
_B_, open at both ends, and terminating in a point at its upper
extremity: it is also provided with lateral openings, in order to
prevent the solution being carried up to the flame. The second part of
the apparatus is the condenser _C_, 0.03 metre in diameter, and 0.25
metre in length. This terminates at its lower extremity with a cone, and
connects at the side with the tube _T_, slanting slightly downwards. In
the interior of the condenser, the cooler _E_ is contained, the lower
end of which is nearly in contact with the sides of the opening _O_. The
combustion tube _D_, 0.01 metre in diameter, is connected by means of a
cork with the tube _T_; it is bent at right angles, and encloses the
tube _B_, in such a manner as to allow the evolved gas to burn in its
interior. The dish _F_ is placed beneath the opening _O_. If the gas
which burns in the combustion tube contains arsenetted hydrogen, water
and arsenious acid are produced. A portion of this acid is retained in
the tube _D_, the remainder is carried over, with the aqueous vapor,
into _C_, where it condenses, and finally falls into the dish _F_. Both
portions are subsequently examined by means of reactions necessary to
establish the presence of the acid. If the ignited gas contains
antimonetted hydrogen, water and an intermediate oxide of antimony are
formed. The latter compound is entirely retained in the tube _D_
separated from the greater part of the arsenious acid, if this body be
present, and can be brought into solution by means of a mixture of
hydrochloric and tartaric acids. A fluid is then obtained which can be
introduced into Marsh's apparatus, or otherwise examined for antimony.


NAQUET'S APPARATUS.

  [Illustration: Fig. 8.]

Although the separation of arsenic from antimony is the chief object in
making use of the apparatus proposed by Flandin and Danger, it is
evident that this result is not fully accomplished, since a small
portion of arsenious acid remains in the tube _D_ (Fig. 7), together
with the intermediate oxide of antimony. The following method secures
the complete separation of these metals: An amalgam of sodium and
mercury is introduced into the flask _A_, (Fig. 8), which is provided
with two openings. The tube _B_, terminating in a funnel at its upper
extremity, passes through one of these orifices. The other aperture
contains a cork enclosing the small tube _C_, which is bent at a right
angle and communicates, by means of a cork, with the larger tube _D_
filled with cotton or asbestus. A set of Liebig's bulbs, _E_, containing
a solution of nitrate of silver, is attached to the other extremity of
this tube. The apparatus being mounted, the solution under examination
is slightly acidulated and introduced by means of the tube _B_ into the
flask _A_: the disengagement of gas begins immediately. If arsenic and
antimony are contained in the solution, arsenetted hydrogen and
antimonetted hydrogen are evolved. Both gases are decomposed in passing
through the solution of nitrate of silver contained in the Liebig bulbs:
the arsenetted hydrogen causes a precipitation of metallic silver, all
the arsenic remaining in solution as arsenious acid; the antimonetted
hydrogen is decomposed into insoluble antimonate of silver. After the
operation has continued for several hours, the apparatus is taken apart,
the nitrate of silver solution thrown on a filter, and the precipitate
thoroughly washed. An excess of hydrochloric acid is then added to the
filtrate, and the precipitate formed separated from the solution by
filtration, and well washed. The wash-water is added to the solution,
and the whole then examined for arsenic by means of Marsh's test.

The precipitate formed in the nitrate of silver solution, which
contains antimonate of silver, is well dried, mixed with a mixture of
carbonate and nitrate of soda, and calcined in a porcelain crucible for
about three-quarters of an hour. The crucible is then removed from the
fire, and the cooled mass treated with hydrochloric acid until a drop of
the filtered fluid ceases to give a residue when evaporated upon a
watch-glass to dryness. A current of sulphurous acid is now conducted
through the filtered solution until the odor of this gas remains
persistent. The excess of acid is then removed by boiling, and the
solution placed in Marsh's apparatus and tested for antimony.


DETECTION OF MERCURY.

If a mercurial salt exists in a considerable quantity in the substances
extracted from the alimentary canal, or ejected either by stools or
vomiting, it can be isolated by treating these materials with water,
filtering the liquid, and evaporating the filtrate to dryness. The
residual mass is taken up with alcohol, and the solution again filtered
and evaporated. Upon dissolving the residue obtained by this operation
in ether and filtering and evaporating the solution, a residue is
obtained which when dissolved in water forms a fluid wherein the
presence of mercury can be detected by means of the ordinary tests.

When, however, only a minute quantity of mercury is present, and this
has been absorbed, its detection is more difficult. It will be necessary
under these circumstances to make use of either Smithson's pile or
Flandin and Danger's apparatus.


SMITHSON'S PILE.

Smithson's pile consists of a small plate of copper around which a
piece of thin gold foil is wrapped. This is immersed in the solution to
be tested for mercury, which has previously been slightly acidulated: if
mercury be present, the plate acquires a white color which disappears
upon exposure to the flame of a spirit-lamp. A similar reaction occurs
in presence of tin, as this metal would likewise be deposited upon the
plate, and, upon heating, would penetrate the metal and restore to it
its natural color. The danger of mistake arising from this fact is
obviated by introducing the copper plate into a tube closed at one end
and bent at a right angle. The open extremity of the tube is drawn out
to a fine point and immersed in water contained in a second tube also
closed at one end. Upon heating the plate in the flame of an alcohol
lamp, the white color disappears if produced by mercury, and at the same
time this metal condenses in the narrow extremity of the tube. The
metallic globules formed can be recognized either by the naked eye or
with the aid of a lens, or by rubbing them with a piece of gold foil
when the latter will acquire a white coating.

When Smithson's pile is employed, the organic substances are most
advantageously decomposed by means of chlorine. It is advisable to
operate with as small a quantity of fluid as possible, for, owing to the
volatility of bichloride of mercury, a portion of this salt may be lost
by the evaporation of aqueous, alcoholic, and even etherial solutions,
and the detection of minute quantities rendered impossible.


APPARATUS PROPOSED BY FLANDIN AND DANGER.

  [Illustration: Fig. 9.]

This apparatus consists of a stand _S_, (Fig. 9) supporting a balloon
_A_, which serves as the reservoir of the suspected solution, and a
funnel _B_, into which the neck of the balloon is dipped. The funnel _B_
is bent at a right angle and is drawn out at its lower end under which
the dish _C_ is placed for the reception of the escaping fluids. A fine
wire of pure gold, forming the negative electrode of a Bunsen's battery,
passes through the lower extremity of the funnel. The end of this wire
nearly comes in contact with a second wire, inserted in the upper part
of the funnel, and connected with the positive pole of the battery. If
the balloon filled with the solution is inverted and immersed in the
funnel _B_, its neck will be submerged at first; soon, however, it
becomes uncovered, owing to the depression of the level of the fluid
caused by the escape of the latter through the tapering extremity of the
funnel: a bubble of air then passes in the balloon and expels a drop of
the solution. This process is repeated at short intervals, causing a
continuous flow of the fluid, the rapidity of which is easily regulated
by elevating or lowering the balloon, thus raising or depressing the
level of the liquid. The apparatus having been mounted in this manner
and the battery set in action, the disengagement of gas commences.
Should mercury be contained in the solution under examination, this
metal will be deposited upon the negative wire. When the operation is
completed this wire is detached from the apparatus, washed with ether,
and dried. It is then introduced into a small tube provided with a bulb,
and the mercury volatilized by means of the blow pipe flame: the metal
condenses in the bulb of the tube in globules which are readily
recognized. They can also be dissolved in nitric acid, and the presence
of a mercurial salt in the solution confirmed by further tests.

The solution to be examined in the preceding apparatus, is prepared as
follows:

The suspected organic matter is treated with cold sulphuric acid of 66°
_B._ until liquefied, and hypochlorite of lime, and distilled water then
added: if necessary, the evolution of chlorine can be accelerated by a
further addition of sulphuric acid. As soon as the liquid becomes clear,
it is filtered, concentrated and examined as described above. The
solution contains the mercury in the state of bichloride, a salt soluble
in water and well adapted to the above test.

The substitution of a large balloon, having a capacity of about 2
litres, in place of the small vessel of Flandin and Danger's apparatus,
is to be recommended as doing away with the necessity of evaporation; an
operation which invariably causes a loss of substance. The apparatus,
modified in this manner, is the most delicate in use for the detection
of mercury.


DETECTION OF PHOSPHORUS.


ORFILA'S METHOD.

The solid substances found in the alimentary canal are mechanically
separated from the fluids present by means of a linen cloth. They are
then examined by aid of a magnifying glass, and any fragments of
phosphorus found separated and preserved under water. If none are
discovered, the presence of phosphorescent vapors may possibly be
detected by examining the materials in the dark. In any case, a portion
of the suspected materials should be treated with nitrate of silver: in
presence of phosphorus the materials acquire, first, a reddish-brown,
then, a black color. The remaining portion is spread upon a shovel and
heated: a white flame, burning at various points of the mass, and
originating from the combustion of phosphorus, is observed, if this body
be contained in the substances under examination. This method is
evidently far from perfect.


MITSCHERLICH'S METHOD.

Mistcherlich's method is based upon the luminosity of the vapors of
phosphorus. The suspected materials are moistened with dilute sulphuric
acid, and heated, in a flask communicating with a glass worm which
passes through a glass cooler into a receiver. If the apparatus is
placed in the dark, and the materials contain phosphorus, luminous
vapors will be observed in the flask and receiver. When the quantity of
the poison present is considerable, the phosphorous acid formed can be
collected and its properties tested.


DUSART'S METHOD, AS MODIFIED BY BLONDLOT.

  [Illustration: Fig. 10.]

Dusart's process takes advantage of the facility with which hydrogen
combines with phosphorus. The substances under examination are placed
between two asbestus stoppers in a tube, one end of which tapers to a
point, and a current of pure hydrogen conducted over them. In presence
of phosphorus the evolved gas will burn with a green flame, and, upon
bringing this in contact with a porcelain plate, red spots will be
deposited upon the latter. _Blondlot_ prefers to introduce the suspected
materials into the flask in which the hydrogen is generated. He employs
the apparatus represented in Fig. 10: _a_ is a flask for evolving
hydrogen; _b_ is a U tube, filled with fragments of pumice stone which
are saturated with a concentrated solution of potassa; _c_ is a Mohr
clamp; _d_ a screw-clamp; _e_ a platinum jet. This jet is necessary in
order to avoid a yellow coloration of the flame by the soda contained in
the glass. Pure hydrogen is at first evolved, in order to ascertain that
the flame is colorless and red spots are not produced when it is
intersected by a cold plate. The purity of the reagents used having thus
been confirmed, the clamp _d_ is closed until the acid is forced back
into _f_; and the materials to be examined are then added to the fluid.
Upon opening the clamp the liquid passes from _f_ into _a_, and the
evolution of gas recommences. The gas is then ignited: the flame
possesses the characteristic properties mentioned above, if the
suspected substances contain phosphorus.


METHOD PROPOSED BY FRESENIUS AND NEUBAUER.

According to this method, the materials are brought into a flask
provided with a doubly-perforated stopper, and water, acidulated with
sulphuric acid, added. The flask is then heated over a water-bath, and a
current of carbonic acid conducted through the mixture for at least two
hours. The gas, on leaving the flask, passes into a solution of nitrate
of silver. Should no precipitate form in this solution, the absence of
free phosphorus is established, for, were this body present, a portion
would be volatilized, and a black precipitate, consisting of phosphide
of silver, together with phosphoric acid, produced. The formation of a
black precipitate is, however, not necessarily a proof of the presence
of phosphorus. In order to conclusively determine the character of the
precipitate, it is collected on a filter and examined by the method of
Dusart and Blondlot.

This process has given result in cases where none were obtained by
Mistcherlich's method. It possesses, moreover, an advantage over the
latter process, in not being influenced by the presence of foreign
bodies; whereas, in Mistcherlich's method, some time must elapse before
the luminosity of the vapors becomes apparent if ether or alcohol is
contained in the solutions, and this phenomenon totally fails to appear
in presence of oil of turpentine.


DETECTION OF PHOSPHORUS BY THE USE OF BISULPHIDE OF CARBON.

In a report read before the Academy of Sciences in 1856, presented by an
examining commission, of which MM. _Dumas_, _Pelouze_ and _Claude
Bernard_ were the reporters, the following results were contained:
Phosphorus may remain, in the _free state_, in the organs fifteen days
after death, and even then its isolation can easily be accomplished. For
this purpose the stomach or intestines, and the articles of food
contained therein, are cut into pieces and treated with bisulphide of
carbon. Upon filtering the liquid, a solution is obtained containing all
the phosphorus present, which exhibits the following properties: 1st,
When ignited, it burns with a very luminous flame; 2nd, if allowed to
spontaneously evaporate (the combustion of the phosphorus being
prevented by the organic matter present [_Naquet_]) an inflammable
residue is obtained, which, if dissolved in boiling monohydrated nitric
acid, gives a solution that, after saturation with ammonia, produces a
precipitate soluble in acids in solutions of barium salts. If the
solution is mixed with perchloride of iron, and the sesquioxide of this
metal subsequently eliminated by the addition of ammonia, it no longer
causes a precipitation in barium solutions. The fluid acquires a yellow
coloration when boiled with a solution of molybdate of ammonia.

According to our personal experience, the apparatus employed by Flandin
and Danger for the detection of arsenic, can also be made use of in the
examination of the bisulphide of carbon solution. To this end, the fluid
supposed to contain phosphorus is mixed with perfectly pure alcohol, and
the mixture placed in a small spirit-lamp provided with a very loose
asbestus wick. The lamp is then ignited and the flame introduced in the
combustion tube _D_ (Fig. 11).

  [Illustration: Fig. 11.]

By the combustion of the mixture, sulphurous, carbonic, phosphorous
acids and water are formed. The water condenses in _c_, and, falling
into the dish _F_, carries with it the sulphurous and phosphorous acids.
The acid liquid collected in this way is evaporated to dryness, some
nitric acid added, and the solution again evaporated. The remaining mass
is then dissolved in water to which some ammonia is added, and the
solution tested for phosphoric acid. This method is an advantageous one
as the phosphoric acid formed must originate from phosphorus in the
_free state_, and not from any phosphates which, owing to the presence
of organic matter, might be contained in the bisulphide of carbon
solution. It would, however, lead the analyst into error if the person,
supposed to have been poisoned had eaten cerebral substances or eggs
previous to death, as these contain glycero-phosphoric acid; it is
therefore advisable to compare the results given by this process with
those obtained by the use of other methods.


DETECTION OF PHOSPHOROUS ACID.

Provided free phosphorus has not been detected, it is necessary to
search for phosphorous acid. To this end, the residue remaining in the
flask, in either Mistcherlich's or Fresenius and Neubauer's method, is
introduced into the apparatus of Dusard and Blondlot. If the phosphorus
reaction appears, it is sufficient; otherwise, its production may have
been hindered by the presence of organic matter. In case, therefore, the
flame is colorless, the evolved gas is conducted into a neutral solution
of nitrate of silver. If the materials contain phosphorous acid, a
precipitate of phosphide of silver is formed which should be collected
and washed. The precipitate, which is now free from organic matter, is
then examined for phosphorous acid by means of the apparatus of Dusard
and Blondlot.


ESTIMATION OF PHOSPHORUS.

The best process for determining quantitatively the amount of
phosphorus present is the one recommended by Fresenius and Neubauer. The
gaseous current is continued until a fresh nitrate of silver solution is
no longer precipitated. The solution is filtered, the precipitate washed
and then dissolved in nitric acid. The silver is next precipitated by
addition of hydrochloric acid, the fluid again filtered, and the
precipitate well washed. The washings are added to the filtrate, and the
liquid concentrated in a porcelain capsule. A solution of sulphate of
magnesia, containing ammonia, is next added to the fluid, and the
phosphoric acid determined as pyrophosphate of magnesia: the precipitate
formed, is washed, heated to redness, in order to convert it into the
pyrophosphate, and then weighed.


DETECTION OF ACIDS.

The search for acids is to be instituted exclusively in the alimentary
canal and its contents. Were acids contained in the other organs, their
presence would be due to the blood in which they had previously been
absorbed, and, as in this case they would be partially neutralized by
the bases contained in the blood, a conclusive decision in regard to
their original existence in the suspected materials would be impossible,
the salts of the acids usually searched for being normal constituents of
the blood. In order to detect the presence of acids, the alimentary
canal and contents are first boiled with water which is renewed until
the solution ceases to exhibit an acid reaction when tested with litmus
paper. The fluid is then filtered, alcohol added to the filtrate, in
order to precipitate organic substances, the liquid again filtered, and
the solution tested separately for the various acids as directed below.


HYDROCHLORIC ACID.

The solution is placed in a retort provided with a receiver and
distilled until the residual fluid assumes a pasty consistence: the
operation is then discontinued. If hydrochloric acid be present in the
materials under examination, the distillate will have an acid reaction,
and, upon addition of solution of nitrate of silver, a white
precipitate, which is easily soluble in ammonia but insoluble in nitric
acid and in short possesses all the properties of chloride of silver,
will be formed.


NITRIC ACID.

The distillate, obtained as in the preceding process, is neutralized by
the addition of potassa or soda, and evaporated to dryness. The residue
is mixed with copper filings, and introduced into a glass tube closed at
one end and provided at the other with a cork through which a
delivery-tube passes. Sulphuric acid is then added to the mixture, the
cork inserted, the tube heated, and the evolved vapors conducted into a
solution of protosulphate of iron. The latter solution acquires a brown
coloration which, upon addition of sulphuric acid, changes to a violet,
if nitric acid be present. Upon conducting the disengaged gas into a
solution of narcotine, the latter acquires a beautiful red color.

Another portion of the residue should deflagrate when saturated with an
alkali and projected upon live coals.


SULPHURIC ACID.

In order to detect this acid, the solution obtained by treating the
organs with water is not distilled but is concentrated to one-sixth of
its original volume, and then agitated with ether for about ten minutes.
By this treatment the ether takes up the free sulphuric acid, but not
the acid sulphates present. After ten minutes contact, the ether is
decanted and allowed to spontaneously evaporate. Upon treating the
residue, which contains the free sulphuric acid and fatty substances,
with water, a solution containing only the sulphuric acid is obtained.
Nitrate of baryta is then added to a portion of the fluid: in presence
of sulphuric acid, a white precipitate, insoluble in acids, is produced.
If this is heated on charcoal before the blow-pipe, a mass is formed,
which, when moistened with hydrochloric acid and placed upon a clean
silver coin, produces a black spot on the metal. Another portion of the
solution is mixed with copper and the mixture evaporated in a tube
closed at one end: sulphurous acid is evolved towards the end of the
operation. This gas is detected by allowing it to pass over paper
saturated with a mixture of iodic acid and starch; a blue coloration is
produced which, owing to the transformation of the iodine set free into
hydriodic acid, subsequently disappears. (We have never been able to
effect the disengagement of sulphurous acid spoken of above when an
exceedingly dilute sulphuric acid was used, even upon evaporating the
mixture to dryness, notwithstanding Orfila's statement that the reaction
occurs very readily.)


PHOSPHORIC ACID.

The aqueous solution is evaporated to dryness, the residue taken up
with alcohol of 44° B., the fluid again evaporated, and the second
residue dissolved in water. Upon adding acetate of lead to the solution,
a white precipitate is produced if phosphoric acid be present. The
precipitate is washed, suspended in water and a current of sulphuretted
hydrogen passed through the mixture. If the fluid is then filtered, and
the excess of sulphuretted hydrogen expelled from the filtrate by
boiling, a liquid possessing the distinctive properties of a solution of
phosphoric acid will be obtained. This should then be submitted to the
following tests: Some pulverized charcoal is added to a portion of the
solution, the mixture evaporated to dryness, and the residue obtained
introduced into a Hessian crucible heated to redness: in presence of a
considerable amount of the acid, free phosphorous is liberated and burns
with a bright flame in the upper part of the crucible. In case this
reaction fails to occur, other portions of the fluid are treated with a
solution of a baryta salt, which causes a white precipitate, soluble in
nitric acid; with an ammoniated solution of sulphate of magnesia, which
throws down a crystalline white precipitate; and by boiling with
molybdate of ammonia, acidulated with nitric acid, which produces a
yellow precipitation, or at least a yellow coloration of the solution.


OXALIC ACID.

The solution is subjected to the same treatment as in the search for
phosphoric acid, with the exception that, instead of adding acetate of
lead to the fluid obtained by taking up the residue left from the
alcohol with water, it is divided into two portions which are examined
separately. A solution of a lime salt is added to one portion: if oxalic
acid be present, a precipitate, which is insoluble in acetic acid or in
chloride of ammonium, and effervesces when slightly calcined and treated
with hydrochloric acid, is formed. Nitrate of silver is added to the
remaining portion of the solution: the formation of a precipitate, which
detonates when dried and heated in a glass tube closed at one end, is
further evidence of the presence of the acid.


ACETIC ACID.

The solution obtained by treating the alimentary canal with water is
distilled, as in testing for nitric and hydrochloric acids, and the
following properties verified in the distillate: 1st. It has an acid
reaction, and possesses the odor of vinegar; 2nd, unless previously
neutralized with a base, it fails to redden the per-salts of iron; 3rd,
if the distillate is added to a solution of the per-salts mentioned and
sulphuretted hydrogen conducted through the fluid, a black precipitate
is formed; 4th, upon boiling the still acid fluid with a small quantity
of starch, the property of the latter to become colored in presence of
free iodine is not changed; 5th, if heated with an excess of litharge, a
basic salt which restores the blue color to reddened litmus paper is
produced.


HYDROCYANIC ACID.

The detection of hydrocyanic acid requires special precautions. The
substances to be examined are mixed with water, if solids are present,
and introduced into a retort provided with a delivery-tube which dips in
a solution of nitrate of silver. The retort is then heated over a
water-bath. If the evolved vapors produce a precipitate in the silver
solution, the heating is continued until a fresh portion of the latter
is no longer affected. The operation is now interrupted, hydrochloric
acid added to the retort, and heat again applied. Should a second
precipitation of cyanide of silver occur, the presence of a _cyanide_ in
the suspected materials is indicated; whereas the formation of a
precipitate by the simple action of heat would point to the presence of
free hydrocyanic acid or cyanide of ammonium.[H] In case the latter
compound is present, ammonia will be contained in the distillate.

  [H] Ferrocyanides and ferricyanides--non-poisonous
  compounds--likewise, evolve hydrocyanic acid when distilled with a
  strong acid. Their presence is indicated by stirring a small portion
  of the materials with water, filtering the fluid, acidulating the
  filtrate with hydrochloric acid, and testing two portions: one with
  sesquichloride of iron, the other with protosulphate of iron. If
  either of the above salts be present, a blue precipitate is
  produced.--_Trans._

In order to identify the cyanogen, a portion of the precipitate is
collected upon a small filter, washed, dried, and then allowed to fall
into a rather long tube, closed at one end, in the bottom of which some
iodine has previously been placed. A column of carbonate of soda is then
introduced above the precipitate for the purpose of retaining the excess
of iodine probably taken. Upon heating the lower end of the tube, white
fumes of iodide of cyanogen, which condense in needles upon the cold
portion of the tube, are produced. These are easily recognized by aid of
a magnifying glass. They are colorless and are readily volatilized by
heat. Some ammonia is next added to a solution of protosulphate of iron,
the precipitate formed thoroughly washed, and exposed to the air until
it acquires a greenish hue. The iodide of cyanogen is then withdrawn
from the tube and mixed with potassa-lye and the precipitate mentioned
above. The mixture is evaporated to dryness, the residue obtained
treated with water and the filtered solution then acidulated with
hydrochloric acid. If a solution of a persalt of iron is now added to
the fluid, a blue precipitate is formed. The addition of salts of copper
produces a reddish precipitation.

The remainder of the precipitate formed in the nitrate of silver
solution is heated with sulphur and then boiled with an aqueous solution
of chloride of sodium: if cyanogen is contained in the precipitate, a
solution of sulphocyanate of soda will be formed, and upon adding
sesquichloride of iron an intense red coloration produced.

It is evident that the presence of another acid in the solution
examined for hydrocyanic acid would render the detection of _cyanides_
impossible, but in all cases hydrocyanic acid can be separated without
arriving at a decision in regard to its original state of combination.
Nitric, hydrochloric, and several other acids would not be distilled at
the temperature of the water-bath; an examination for these by the
methods already described can therefore be instituted simultaneously
with the search for hydrocyanic acid.


DETECTION OF ALKALIES AND ALKALINE EARTHS.

The separation of these bodies in the caustic state is a matter of
difficulty owing to the great tendency they possess to become converted
into carbonates; the carbonates of lime, baryta and strontia, moreover,
being non-poisonous in their effects, will not be employed with criminal
intent, and the carbonates of soda and potassa are extensively used as
pharmaceutical preparations. Notwithstanding the small chances of
success, the isolation of the compounds under consideration in the
caustic state is to be attempted.

To this intent, the organs to be analysed, together with their
contents, are placed in a glass retort provided with a receiver, water
added, and the mixture boiled. The distillate will contain the ammonia
present. When, however, putrefaction has begun, the detection of this
compound does not necessarily indicate its original presence in the
suspected materials. If, after an hour's boiling, the fluid in the
retort possess an alkaline reaction, it is to be examined for soda,
potassa, strontia, baryta and lime. The undistilled solution is
filtered, the filtrate evaporated to dryness, and the residual mass
treated with alcohol. By this treatment, potassa and soda go in
solution, lime, baryta and strontia[I]--as well as the alkaline
carbonates--remaining undissolved. The potassa and soda are separated
from the other salts present by filtering and evaporating the alcoholic
solution to dryness and then calcining the residue in a silver crucible.
The mass, which should still be alkaline, is then dissolved in dilute
sulphuric acid. If the solution is turbid, traces of baryta or strontia
may still be present and should be removed by filtration. Some
hydrochloric acid and solution of bichloride of platinum are then added
to a portion of the filtered liquid: in presence of _potassa_ a yellow
precipitate is formed.

  [I] Baryta and strontia dissolve in alcohol, but only when they are
  anhydrous and the alcohol is absolute, which is not the case here.

Another portion is treated with tartaric acid: a white granular
precipitate is produced. Hydrofluosilicic acid is added to a third
portion of the solution: the formation of a gelatinous precipitate is a
further indication of the presence of potassa. If the preceding tests
have given negative results, and a white precipitate is formed by the
addition of antimonate of potassa to another portion of the solution,
_soda_ is present. In both cases, it is necessary to confirm the results
by means of the spectroscope.

The above reactions are distinctive only in the absence of metals
precipitated by sulphuretted hydrogen, sulphide of ammonium or carbonate
of soda, and small portions of the solution should be tested with these
reagents.

In order to detect baryta, strontia and lime, the residue, insoluble in
alcohol is dissolved in dilute nitric acid, and an excess of carbonate
of ammonia added to the solution: the three bases, if present, are
precipitated as carbonates. The precipitate formed is separated from the
solution by filtration, dissolved on the filter in dilute hydrochloric
acid, and the solution then filtered and divided into two parts:
sulphuric acid is added to one, the fluid filtered from the precipitate
of sulphate of baryta formed, and the filtrate treated with ammonia and
oxalate of ammonia. If _lime_ be present,--although its sulphate is not
easily soluble--sufficient will be contained in the filtrate to give a
white precipitate of oxalate of lime.

The remaining portion of the solution is evaporated to dryness, and the
residue treated with absolute alcohol. Chloride of strontium goes into
solution, chloride of barium remaining undissolved. If upon evaporating
the alcoholic solution a residue is obtained which, when dissolved in
water, produces turbidity in a solution of sulphate of lime, _strontia_
is present.

The residue, insoluble in alcohol, is dissolved in water. If a
precipitate is produced by the addition of sulphuric acid or
hydrofluosilicic acid to the solution, _baryta_ is present. The latter
reaction distinguishes baryta from strontia, which is not precipitated
by hydrofluosilicic acid. Should the tests mentioned above fail to give
affirmative results, and poisoning by means of baryta and strontia be
nevertheless suspected, these compounds may possibly have remained in
the materials contained in the alimentary canal, in the state of
insoluble sulphates. To effect their detection under these circumstances
the organic substances must be decomposed by means of sulphuric acid.
The carbonaceous residue is calcined in a crucible at an elevated
temperature, and the remaining mass treated with water. In this way, a
solution of sulphides of barium and strontium is obtained, which is then
tested as directed above.


DETECTION OF CHLORINE, BROMINE, AND IODINE.


CHLORINE AND BLEACHING CHLORIDES.

The detection of chlorine is very difficult owing to the great tendency
it possesses to become converted into chlorides or hydrochloric acid,
and it is only when found in a free state that its discovery is of
importance.

In case the gas exists uncombined in the alimentary canal, its odor
will be perceptible, and, upon boiling the suspected materials with
water, vapors will be evolved which impart a blue color to paper
saturated with a mixture of iodide of potassium and starch paste. If the
addition of sulphuric acid is necessary in order to produce the above
reactions, there is reason to suspect the presence of "chloride of lime"
or "_Eau de Javelle_."[J]

  [J] The so-called "chloride of lime" is probably either a mixture of
  chloride and hypochlorite of calcium or an oxydichloride of the metal;
  "_Eau de Javelle_" is the corresponding potassium compound.--_Trans._


BROMINE.

In case bromine exists in a free state at the time the autopsy is made,
its presence will be detected by the reddish color and unpleasant odor
it possesses. Its isolation is accomplished by treating the materials
with bisulphide of carbon which, upon dissolving the bromine, acquires a
red color. If potassa is then added to the solution, it combines with
the bromine and, upon evaporating the decanted fluid, calcining the
residue, and treating it with water, a solution of bromide of potassium
is obtained. Upon adding chlorine-water and ether to a portion of the
fluid, and shaking the mixture, the bromine is liberated and is
dissolved by the ether. The etherial solution of bromine, which
possesses a reddish-yellow color, does not mingle with, but floats upon
the surface of the colorless aqueous solution.

If nitrate of silver is added to another portion of the aqueous solution
of bromide of potassium, a precipitate of bromide of silver, soluble in
ammonia, is formed.

In case the bromine has been converted into a bromide, it is necessary
to boil the alimentary canal and the articles of food contained therein
with water. The fluid is next filtered and agitated with chlorine-water
and ether. The liberated bromine is dissolved by the ether, which
acquires a reddish-yellow color. Upon decanting the solution, and
treating it with potassa, bromide of potassium is formed, and can be
detected as directed above.


IODINE.

The detection of iodine is accomplished by a process almost identical
with the above. The isolation of the iodine having been effected, it
remains to be ascertained that it imparts a blue color to starch paste,
and a violet color to bisulphide of carbon.


DETECTION OF METALS.

Under this head we will indicate the systematic course of analysis to be
pursued, supposing a mixture of several metals including arsenic and
antimony, to be under examination.

The organic substances are first destroyed by means of chlorate of
potassa and hydrochloric acid. When this is accomplished, the excess of
chlorine is removed by boiling and the liquid filtered. The portion
remaining on the filter is preserved: it contains all the silver and a
large portion of the lead, if these metals are present. We will
designate the residue as A, the filtrate as B.


TREATMENT OF RESIDUE A.

The residue is calcined with a little carbonate of soda and cuttings of
pure Swedish filtering paper, the chlorides present being reduced to the
metallic state by this treatment. The residue is next taken up with
water acidulated with nitric acid, and the solution filtered. An
insoluble residue, that may remain, is washed with hot water until the
wash-water ceases to precipitate solution of nitrate of silver, and
dried. It is then dissolved in boiling nitric acid, the solution diluted
with water, and filtered.[K]

  [K] If an insoluble residue remains by the treatment with nitric
  acid, it may consist of _tin_. In this case, it is dissolved in _aqua
  regia_, the metal precipitated by immersing a plate of zinc in the
  solution and then re-dissolved in boiling hydrochloric acid. Upon
  adding chloride of gold to the solution so obtained, a purple
  precipitate is formed. Sulphuretted hydrogen produces a brown
  precipitate, soluble in sulphide of ammonium, in presence of tin.

Sulphuric acid is added to the filtrate: if no precipitate forms, the
absence of _lead_, in the residue A, is indicated. If, on the contrary,
a precipitate is produced, it is collected upon a filter and washed. In
order to make sure that the precipitate consists of sulphate of lead, it
is treated with a solution of tartrate of ammonia: it should dissolve,
forming a solution in which sulphuretted hydrogen produces a black
precipitate.

The fluid which has failed to be precipitated by the addition of
sulphuric acid, or the filtrate separated from the precipitate formed,
can contain only silver. Upon adding hydrochloric acid, this metal is
thrown down as a caseous white precipitate, which is soluble in ammonia,
but insoluble in boiling nitric acid, and blackens upon protracted
exposure to light. The formation of a precipitate possessing these
properties, leaves no doubt as to the presence of _silver_.

_Remark._--In the operations described above, as well as in those
following, the difficulty in separating minute precipitates from the
filter is often experienced. When the precipitate is to be dissolved in
reagents that do not affect the paper, such as ammonia, tartrate of
ammonia, and dilute acids, it can be brought in solution directly on the
filter. In cases, however, where reagents which attack the paper are
employed, the precipitate should be separated. This is accomplished by
mixing a small quantity of pure silica, obtained by the decomposition of
fluoride of silicium by water, with the solution, before filtering. The
precipitate becomes intimately mixed with the silica, and can then be
readily removed from the paper. The presence of silica does not
interfere, it being insoluble in the reagents commonly made use of.


TREATMENT OF FILTRATE B.

A current of sulphuretted hydrogen is conducted for twelve hours through
the solution, which is kept at a temperature of 70°. by means of a
water-bath. The flask containing the liquid is then closed with a piece
of paper, and allowed to remain in a moderately warm place until the
odor of the gas is no longer perceptible. The solution is next filtered
with the precaution mentioned in the preceding remark, and the
precipitate (_a_) thoroughly washed. The water used in this operation is
united to the filtrate, and the fluid (_b_) examined as directed further
on.


TREATMENT OF PRECIPITATE _a_.

In order to free the precipitate from the organic substances possibly
present, at the same time avoiding a loss of any metal, it is dried,
moistened with nitric acid, and the mass heated on a water-bath. Some
Swedish filtering paper is next added, the mixture well impregnated with
sulphuric acid, and then maintained for several hours at a temperature
of about 170°. until a small portion (afterwards returned) gives a
colorless solution when treated with water. The residue is now heated
with a mixture of one part of hydrochloric acid and eight parts of
water, the liquid filtered, the matter remaining undissolved washed with
dilute hydrochloric acid, and the washings united with the filtrate.

The residue I. and the solution II. are separately examined as directed
below.


RESIDUE I.

This may contain lead, mercury, tin, bismuth and antimony. It is heated
for a considerable time with _aqua regia_, the solution filtered, and
the second residue, should one remain, washed with dilute hydrochloric
acid. If the second residue is fused with cyanide of potassium, the
compounds present are reduced to the metallic state. The liberated
metals are treated with nitric acid, which dissolves _lead_, but leaves
_tin_ as insoluble metastannic acid. The nitrate of lead is then
filtered from the metastannic acid, and both metals are identified as
described in the treatment of residue A.

The solution, obtained by the action of _aqua regia_ on residue I, is
treated with sulphuretted hydrogen. The tin and antimony are separated
from the lead, mercury and bismuth by treating the precipitate produced
with sulphide of ammonium, which dissolves only the sulphides of the
first two metals. The solution in sulphide of ammonium is afterwards
examined for these metals, as directed under the head of solution IV.,
the search for arsenic, however, being here omitted.

Upon treating the residue insoluble in sulphide of ammonium with nitric
acid, lead, copper and bismuth go into solution, mercury remaining
undissolved. The liquid is filtered, and the undissolved mercury
submitted to the special examination previously described.

Sulphuric acid is added to the solution and the precipitate of sulphate
of lead formed, separated, washed, and examined as directed while
treating of residue A.

Finally, the solution separated from the lead is tested for _bismuth_
and _copper_, as in examination of precipitate III.


SOLUTION II.

The solution is concentrated by heating on a water-bath, a small
quantity of carbonate of soda cautiously added to a portion, and notice
taken if a precipitate forms. The part taken is then acidulated with a
little hydrochloric acid, returned to the principal solution, and
sulphuretted hydrogen conducted through the fluid, as in the examination
of solution B. In case a precipitate fails to form, all metals are
absent; if, on the contrary, a precipitate (_c_) is produced, it is
examined as directed below.

EXAMINATION OF PRECIPITATE _c_.

If the solution merely became turbid, or the precipitate formed was of
a pure white color, it consists probably of sulphur. It is, however,
indispensable, even in this case, to collect the precipitate and examine
it for _arsenic_. Provided it is of a pure yellow color, it is treated
with ammonia. In case it is entirely dissolved by this treatment, and
the addition of carbonate of ammonia failed to produce a precipitate in
solution II., it is certain that arsenic, and no other metal, is
present. Under these circumstances, the ammoniacal solution is examined
as directed in the article on the detection of arsenic. If, on the other
hand, the precipitate is not yellow, or being yellow, is but imperfectly
soluble in ammonia, and a precipitate was formed by the addition of
carbonate of ammonia to solution II., it is necessary to likewise search
for tin, antimony, mercury, copper, bismuth and cadmium. In this case,
the precipitate is placed in a small flask, allowed to digest for
several hours with ammonia and sulphide of ammonium in a moderately warm
place, and the solution filtered.

The remaining residue (III.) is washed, labelled, and preserved for
subsequent examination; the _filtrate_ (IV.) is treated as directed
below.


TREATMENT OF SOLUTION IV.

The solution, to which the water used in washing the residue has been
added, is evaporated to dryness, the residue obtained taken up with pure
fuming nitric acid, and the liquid again evaporated. The second residue
is next saturated with a solution of carbonate of soda. A mixture of 1
part of carbonate and 2 of nitrate of soda is then added, the mixture
evaporated to dryness, and the residual mass heated to fusion. The fused
mass, when cold, is treated with cold water, and any remaining residue
washed with a mixture of equal parts of alcohol and water. The filtered
fluids are now evaporated in order to remove the alcohol, sulphuric acid
is then added, and the mixture heated until white fumes of the acid
begin to evolve. In this way the complete expulsion of the nitric acid
present is rendered certain. When cold, the residue is treated with
water and the _solution_ introduced into Marsh's apparatus, or, in case
a quantitative estimation of the arsenic is desired, it is treated with
sulphuretted hydrogen and the weight of the precipitate formed
determined, as directed under the detection of arsenic.

Should a residue insoluble in water remain, it may contain tin,
antimony and traces of copper. Upon dissolving it in _aqua regia_ and
placing a sheet of pure zinc in the solution, these metals are thrown
down in the metallic state. The precipitate is collected, the zinc
present completely removed by treatment with _dilute_ hydrochloric acid,
and the residue boiled with concentrated hydrochloric acid which
dissolves the _tin_ present. The fluid is filtered and the _filtrate_
tested for this metal by adding solution of chloride of gold, which, in
its presence, produces a purple precipitate, and, by treating it with
sulphurated hydrogen, which forms a brown precipitate, soluble in
sulphide of ammonium.

If the _residue_, insoluble in concentrated hydrochloric acid, is
thoroughly washed and then treated with nitric acid, the copper present
goes in solution. The fluid is filtered, and ammonia added to the
filtrate: in presence of _copper_, the solution acquires a blue color,
and gives a reddish precipitate upon addition of ferrocyanide of
potassium.

_Antimony_, if present, remains by the treatment with nitric acid as an
insoluble intermediate oxide. This is dissolved in hydrochloric acid, in
which it is now soluble, and the solution introduced into Marsh's
apparatus.


TREATMENT OF PRECIPITATE III.

This precipitate may contain the sulphides of mercury, copper, cadmium
and bismuth. Upon treating it with nitric acid, all but the sulphide of
mercury are dissolved. In case no residue remains, the absence of
_mercury_ is indicated; if, on the other hand, a residue is left, it is
well washed, dissolved in _aqua regia_, and the solution examined,
either by means of Smithson's pile, or in the apparatus of Flandin and
Danger. (_Vide Detection of Mercury._)

Whether a residue remains or not, an excess of ammonia is next added to
the filtered solution in nitric acid: the formation of a permanent
precipitate denotes the presence of _bismuth_. In this case, the fluid
is filtered, and the alkaline filtrate further tested for copper and
cadmium. For this purpose, cyanide of potassium is added, and
sulphuretted hydrogen conducted through the filtrate: if _cadmium_ be
present, a yellow precipitate is produced, copper not being thrown down
in presence of an alkaline cyanide. The precipitate of sulphide of
cadmium is separated from the solution by filtration, and the filtrate
saturated with hydrochloric acid. _Copper_, if present, is now
precipitated as sulphide: its separation is completed by conducting
sulphuretted hydrogen through the fluid.

The precipitate is collected, washed, dissolved in nitric acid, and its
identity established as previously directed. If the metal be present in
sufficient quantity, it should be obtained in a metallic state upon a
plate of iron; it is then coherent, possesses its natural color, and can
conveniently be exhibited to the Jury.


TREATMENT OF SOLUTION _b_.

This solution may contain: cobalt, nickel, iron, manganese, chromium,
zinc and aluminium. Of these, only zinc and chromium are poisonous; the
search for these two metals is therefore all that is necessary in
criminal cases. The solution is treated with a slight excess of ammonia,
sulphide of ammonium added, and the fluid, after being allowed to stand
for several hours, filtered. The precipitate may consist of sulphide of
zinc and hydrated oxide of chromium, as well as of traces of sulphide of
iron and phosphate of lime. If the suspected materials contained a
_chromate_, this salt, in presence of hydrochloric acid and sulphuretted
hydrogen, would be converted into sesquichloride of chromium a compound
which is precipitated by sulphide of ammonium as a hydrated oxide.

The precipitate is washed with water, to which a little sulphide of
ammonium is added, then dried, and fused with four times its weight of a
mixture of equal parts of carbonate and nitrate of potassa. After the
mass has remained in a state of fusion for a quarter of an hour, it is
treated with boiling water, mixed with a little alcohol, in order to
decompose the manganate that would be present were manganese contained
in the materials under examination. The alcohol is then expelled by
boiling the fluid, and the solution filtered. The _filtrate_ may contain
phosphate of potassa, originating from the phosphate of lime present,
and _chromate of potassa_, resulting from the oxidation of the
sesquioxide of chromium. In presence of the latter compound, the
following reactions will occur in the solution: 1st., Upon acidulation
with acetic acid and addition of solution of acetate of lead, a yellow
precipitate, soluble in potassa, is formed; 2nd., if hydrochloric acid
is added and sulphuretted hydrogen conducted into the solution, the
latter acquires a green color, and, upon adding ammonia, a bluish-grey
precipitate of chromic hydrate is produced; 3rd., if nitrate of silver
is added to the solution, a brick-red precipitate is formed.

The _precipitate_ remaining on the filter, may consist of zinc, mixed
with the oxides of iron, nickel, cobalt, aluminium and manganese. It is
dissolved in boiling hydrochloric acid, acetate of soda added, and the
fluid boiled until no further precipitation occurs. The iron is now
completely separated. The solution is then filtered, the precipitate
washed, and an excess of potassa added to the _filtrate_; if the
solution contains cobalt, nickel or manganese--which is improbable--a
permanent precipitate is formed. This is separated from the fluid by
filtration: its further examination is, however, unnecessary, as the
metals of which it consists are not poisonous. The _filtrate_ may
contain aluminium and _zinc_. The latter metal is detected by
acidulating the filtrate with acetic acid, and adding a solution of
sulphuretted hydrogen: in presence of zinc a white precipitate of its
sulphide is formed.

In case organic substances are present, the precipitation of chromium by
sulphide of ammonium may possibly have been hindered, and the metal have
passed into the filtrate. When, therefore, chromium is not detected in
the precipitate, the filtrate should also be examined. For this purpose,
the fluid is evaporated to dryness, and the residue obtained fused with
a mixture of nitrate and carbonate of soda. The fused mass is then taken
up with water, the solution acidulated with acetic acid, and a solution
of acetate of lead added: if chromium be present, a yellow precipitate,
soluble in potassa, is produced.


DETECTION OF ALKALOIDS AND SOME ILL-DEFINED ORGANIC SUBSTANCES.[L]

A general method for effecting the detection of alkaloids was first
proposed by _Stas_. Since the publication of this method, modifications
to it have been recommended by _Otto_, and by _L. Uslar_ and _J.
Erdman_. Other processes have been suggested by _Rodgers_ and _Girwood_,
by _E. Prollius_, and by _Graham_ and _Hofman_. The latter will
doubtless become general in their application; but up to the present
time they have been employed exclusively in the detection of strychnine.
Dialysis has also been recently applied in the separation of alkaloids.

  [L] Colchicine, picrotoxine and digitaline.


STAS'S METHOD.

This method is based upon the facts: (_a_), that the acid salts of the
alkaloids, especially those containing an excess of tartaric or oxalic
acids, are decomposed by caustic alkalies and by the bicarbonates of
soda and potassa; (_b_), that the alkaloids, when liberated in this
manner, are combined with a certain amount of water which determines
their solution in ether, although, in a desiccated state they may be
insoluble in this menstruum; (_c_), that they may be extracted from
their aqueous solutions by agitation with ether.

Stas's original method is as follows: The suspected substances, if
organs are contained, are cut into fine shreds, then mixed with absolute
alcohol, 0.5 to 2. grammes of tartaric or oxalic acid added and the
whole introduced into a flask and heated at a temperature of 60° to 75°.
When quite cold, the mixture is filtered, and the undissolved portion
remaining on the filter washed with absolute alcohol, the washings being
added to the filtrate. The alcoholic solution is evaporated, either by
placing it under a bell-jar connected with an air-pump, or by passing a
current of air, having a temperature not exceeding 35° over it, until
reduced to a quarter of its original volume: the complete expulsion of
the alcohol being then rendered certain. If insoluble matter separates
during this operation, the concentrated fluid is passed through a
moistened filter, the water used in washing the residue being united to
the filtrate which is then evaporated to dryness by aid of the air-pump
or by placing the fluid in a bell-jar over concentrated sulphuric acid.
When the evaporation is completed, the residue is treated with absolute
alcohol, the alcohol allowed to evaporate at the ordinary temperature of
the air, and the second residue dissolved in the smallest possible
amount of water. The fluid thus obtained is placed in a test-tube, and a
concentrated solution of bicarbonate of soda added so long as
effervescence takes place. Ether is then added, the mixture thoroughly
shaken, and after it has remained at rest for some time, a small portion
of the supernatant ether removed and evaporated on a watch-glass: the
residue obtained will consist of the alkaloid present. Two cases are now
possible: the alkaloid is a solid, or it is a liquid and is volatile.

The further treatment of the solution is modified according to these
circumstances.


_a._ THE ALKALOID IS LIQUID AND VOLATILE.

If, upon the evaporation of the ether, oily streaks were left on the
watch-glass, a volatile alkaloid is probably present.

In this case, a solution of caustic potassa is added to the test-tube,
the mixture shaken, the supernatant ether decanted[M] into a flask and
the remaining solution again washed with ether until the last portion
fails to leave a residue upon evaporation. The etherial fluids are then
united, and two cubic centimetres of water, acidulated with one-fifth of
its weight of sulphuric acid, added. This acid retains the alkaloid,
which is now in the state of a pure acid-sulphate soluble in water, the
animal matters present remaining dissolved in the ether. The ether, in
which some sulphate of conia may be contained--although the greater
portion of this compound would remain in the aqueous solution--is then
decanted. The remaining aqueous solution of the pure sulphate of the
alkaloid is placed in a test-tube, a solution of caustic potassa and
some ether added, and the mixture well shaken. The ether is next
decanted and allowed to spontaneously evaporate in a dry place at a very
low temperature, and the ammonia possibly present is then removed by
placing the vessel containing the residue over sulphuric acid. The
residue now obtained consists of the alkaloid present in a state of
purity, and can be directly identified by means of the reactions
described further on.

  [M] The necessity of decanting etherial and other solutions is
  advantageously obviated by the use of a pipette.--_Trans._


_b._ THE ALKALOID IS SOLID.

It sometimes occurs that ether fails to take up all of the alkaloid
present in the fluid treated with bicarbonate of soda. Under these
circumstances the fluid should be mixed with caustic potassa, the
mixture shaken, and the ether decanted; this operation being repeated
several times, until the entire amount of the alkaloid is removed; the
ethereal fluids are then united in a capsule, and allowed to
spontaneously evaporate. The result of the evaporation may be solid;
more frequently, however, a milky liquid remains which restores the blue
color to reddened litmus paper; if so, the presence of a vegetable
alkaloid is certain. In order to purify the residue, a few drops of
water, slightly acidulated with sulphuric acid, are added to the
capsule, and the latter turned, so as to bring the fluid in contact with
the substance at all points; in this manner a colorless and limpid fluid
is obtained, the fatty substances adhering to the dish. The liquid is
decanted into a second capsule, the remaining residue washed with a
little acidulated water, and the washings likewise added to the
principal solution. The fluid is now evaporated either _in vacuo_, or
over sulphuric acid, to about three-fourths of its original volume a
concentrated solution of neutral carbonate of potassa added, and the
mixture treated with absolute alcohol, which dissolves the liberated
alkaloid, and separates it from the sulphate of potassa formed and the
excess of carbonate of potassa. The alcoholic solution is decanted and
allowed to evaporate _in vacuo_ or in the air: the alkaloid now
crystallizes out in a state suitable for further examination.


MODIFICATIONS TO STAS'S METHOD, PROPOSED BY OTTO.

In Stas's method, the loss of morphine is possible, for, if ether is not
added immediately after the addition of carbonate of soda, this alkaloid
crystallizes and is then no longer soluble in that menstruum; and, if
the ethereal solution is not quickly decanted, the portion dissolved
will likewise separate out in small crystals. In both cases, morphine
will remain in the aqueous solution from which the other alkaloids have
been extracted by the ether. _M. Otto_ recommends the addition of
chloride of ammonium and a little soda-lye, in order to dissolve the
alkaloid. Upon allowing the solution so obtained to stand for some time
exposed to the air, crystals of morphine are deposited.

According to the same authority, it is advisable to omit the distinction
drawn by Stas between volatile and fixed alkaloids, and submit both to
the treatment recommended for those that are volatile.

Otto also recommends the agitation of the fluid containing the oxalates
or tartrates of the alkaloids with ether, previously to their separation
by means of bicarbonate of soda. By this treatment the elimination of
the coloring matter present--as well as of _colchicine_, _digitaline_,
_picrotoxine_, traces of _atropine_, and various impurities--is
accomplished. As soon as the ether ceases to become colored and to leave
a residue upon evaporation, alkali is added, and the operation concluded
as usual. In this way the alkaloid is obtained, almost directly, in a
pure condition. This last modification appears to us to be a very happy
one, inasmuch as it greatly facilitates the purification of the alkaloid
present.


MODIFICATIONS TO STAS'S METHOD, PROPOSED BY USLAR AND ERDMAN.

1st. The materials to be examined are brought to the consistence of a
thin paste, and digested for about two hours with water, to which some
hydrochloric acid has been added, at a temperature of 60° to 80°. The
mixture is then filtered through a moistened linen cloth, and the
residue washed with warm acidulated water; the washings being added to
the solution.

2nd. Some pure quartz sand--or, preferably, silica prepared by the
decomposition of fluoride of silicium--is added to the filtrate, the
fluid supersaturated with ammonia, and evaporated to dryness over a
water-bath: the addition of silica renders the residue friable.

3rd. The residue is boiled repeatedly with amylic alcohol, which
extracts all the alkaloid present as well as the fatty and coloring
matters, and the extracts filtered through filter paper that has been
moistened with amylic alcohol.

4th. The filtered fluid is thoroughly agitated with ten or twelve times
its volume of almost boiling water acidulated with hydrochloric acid:
the hydrochlorate of the alkaloid present goes into the aqueous
solution, the fatty and coloring substances remaining dissolved in the
oily supernatant layer. The latter is separated by means of a pipette,
and the acid aqueous solution shaken with fresh quantities of amylic
alcohol until completely decolorized.

5th. The aqueous solution is then concentrated, ammonia added, and the
mixture well shaken with warm amylic alcohol, in which the alkaloid
dissolves. As soon as the solution forms a supernatant layer upon the
surface of the fluid, it is drawn off with a pipette and evaporated on a
water-bath. In this manner, the alkaloid is usually obtained in a
sufficient state of purity to admit of its immediate identification; if,
however, a small portion turns brown when treated with concentrated
sulphuric acid, the process of purification must be repeated. Under
these circumstances it is re-dissolved in dilute hydrochloric acid, the
solution repeatedly shaken with amylic alcohol, in order to extract the
impurities present, and the alkaloid then extracted with ammonia and
amylic alcohol, as previously directed.

The method of _von Uslar_ and _Erdman_ differs from that of Stas merely
in the substitution of amylic alcohol for ether, and of hydrochloric
acid for oxalic or tartaric acid. It offers no advantages over Stas's
method if the alkaloids present are soluble in ether but is even less
advantageous in this case, inasmuch as its execution requires a longer
time. In cases where the detection of morphine, or an unknown alkaloid,
is desired, the use of amylic alcohol instead of ether is, it is true,
preferable; still, with the exercise of care, ether can also be
employed, and, as this process greatly facilitates examinations when no
clew to the poison present exists and all alkaloids may possibly be
absent, we prefer it to the one just described.


RODGERS AND GIRDWOOD'S METHOD.

This method--which as yet has only been employed in the detection of
strychnine--is based upon the solubility of this alkaloid in chloroform.
The substances under examination are digested with dilute hydrochloric
acid, and the mixture filtered. The filtrate is then evaporated to
dryness on the water-bath, the residue taken up with pure alcohol, the
alcoholic solution evaporated, the second residue treated with water,
and the solution so obtained filtered. The filtrate is next
supersaturated with ammonia, and well shaken with chloroform, which,
upon being separated by means of a pipette and evaporated, leaves the
alkaloid in an impure state. Concentrated sulphuric acid is then poured
upon the alkaloid: the latter is not affected by this treatment, whereas
the foreign organic substances present are carbonized. After the lapse
of several hours, the mixture is treated with water, the fluid filtered,
and the strychnine extracted from the filtrate by means of ammonia and
chloroform, as already described. The operation is repeated until the
residue obtained by evaporating the chloroform is no longer affected by
the treatment with sulphuric acid.


PROLLIUS'S METHOD.

The suspected substances are boiled with aqueous alcohol, mixed with
tartaric acid, and evaporated at a gentle heat. The remaining aqueous
solution is then passed through a moistened filter, ammonia added to the
filtrate, and the mixture shaken with chloroform. The chloroform is
separated, the last trace of the original solution removed by washing
with water, three parts of alcohol added, and the fluid evaporated. If
strychnine be present, it will now separate out in crystals. This method
is applicable only in presence of a considerable quantity of strychnine,
and is less serviceable than the one preceding.


GRAHAM AND HOFMAN'S METHOD.

This method, which is applied to the detection of strychnine in beer, is
founded upon the fact that an aqueous solution of a strychnine salt
yields the alkaloid to animal charcoal, from which it can be
subsequently extracted by boiling with alcohol. The beer to be examined
is shaken with 30 grammes of animal charcoal, and the mixture then
allowed to stand twenty-four hours, with occasional shaking. The
solution is next filtered, the animal charcoal washed with water, and
boiled for half-an-hour with four times its weight of 90 per cent.
alcohol. The apparatus represented in Fig. 12 is employed, in order to
avoid a loss of substance in this operation.

  [Illustration: Fig. 12.]

The alcohol is filtered hot, evaporated, and the residue obtained
treated with a small quantity of solution of potassa, and then agitated
with ether. Upon spontaneous evaporation, the ethereal solution leaves
the strychnine present in a comparatively pure state.

_Macadam_ proposes to use this process for the detection of strychnine
in animal bodies. For this purpose, the suspected materials are heated
with a solution of oxalic acid, as in Stas's method, and the strychnine
detected in the filtered solution in the manner just described. This
method is scarcely to be recommended: the use of animal charcoal is
doubtless serviceable in the examination of beer, as it effects the
separation of a small amount of strychnine from a large quantity of
fluid, but its application to other researches is much less to be
advised.


APPLICATION OF DIALYSIS IN THE DETECTION OF ALKALOIDS.

In order to apply the dialytic method to the separation of alkaloids,
the suspected substances are heated with hydrochloric acid, and the
solution introduced into the dialyzer. The hydrochlorates of the
alkaloids, being crystalline bodies, transverse the membrane, and are
contained, for the greater part, after twenty-four hours, in the outer
solution. The fluid is then concentrated, and the alkaloids either
directly precipitated, or purified by one of the preceding methods.


IDENTIFICATION OF THE ALKALOID.

The alkaloid having been isolated by one of the preceding methods, it
remains to establish its identity. Owing to the small number of
reactions characteristic of organic compounds, this is a matter of
considerable difficulty. There are two cases possible: the alkaloid may
either be volatile or fixed.


THE ALKALOID IS VOLATILE.

In this case it may consist of nicotine, conine or aniline: less known
alkaloids (piccoline, etc.) may also be present. We will confine
ourselves to the consideration of the three first mentioned.

The alkaloid is divided into several portions which are placed on
watch-glasses and submitted to the following tests:

_a._ A drop is treated with nitric acid: this may, or
may not, impart a red tint to the alkaloid; if it
does, another drop is treated with dry hydrochloric
acid gas: if it assumes a deep violet color, it
probably consists of                                           _conine_.

_b._ In case a red color was not produced by the
addition of nitric acid, another drop is treated with
chloride of lime. If it acquires a violet tint, and
two other drops, when heated, one with arsenic acid,
the other with nitrate of mercury, become red, the
body present consists of                                     _aniline_.
or an homologous base.

_c._ Should the above tests fail to give positive
results, and the substance, when treated with
chlorine, assumes a blood-red color, and with
hydrochloric acid does not change in the cold but
turns to a deep violet color upon boiling, it probably
consists of                                                 _nicotine_.


THE ALKALOID IS FIXED.

A very minute quantity is dissolved in the smallest possible amount of
hydrochloric acid, and an excess of ammonia added. Three cases are now
possible: (_a_) A precipitate, insoluble in an excess of the
precipitant, is immediately formed; (_b_) a precipitate is formed,
which, at first dissolves, but is subsequently deposited from the fluid;
(_c_) no precipitate is produced, or, in case one forms, it dissolves in
an excess of the precipitant and fails to separate out upon allowing the
fluid to stand.


_a. Ammonia produces a permanent precipitate._

A small quantity of an aqueous solution of carbonic acid is poured over
the alkaloid in the water-glass, and notice taken whether it dissolves
or not: in either case the mixture is evaporated on a water-bath to
dryness, in order to avoid a loss of substance.


CARBONIC ACID FAILS TO DISSOLVE THE ALKALOID.

After the evaporation is completed, ether is added to the watch-glass:
the alkaloid may, or may not, be dissolved. The ether is then evaporated
at the ordinary temperature of the air.

_Ether fails to dissolve the alkaloid._

It probably consists of                                     _berberine_.

In this case, it will possess a yellow color, and its
hydrochlorate will give a reddish-brown precipitate
upon addition of sulphide of ammonia.

_Ether dissolves the alkaloid._--A small portion is
treated with nitric acid. If an intense green
coloration is produced, the remaining portion is
dissolved in ether, and an ethereal solution of oxalic
acid added. If the precipitate now formed does not
dissolve upon the addition of a little water, there is
reason to suppose the presence of                             _aricine_.

Provided the addition of nitric acid did not produce a
coloration, the mixture of the alkaloid and this acid
is treated with a small quantity of sulphuric acid: if
the fluid now acquires a red color, the substance
probably consists of                                        _narcotine_.

Should both nitric and sulphuric acids fail to cause a
reaction, the alkaloid is dissolved in ether,
precipitated by an ethereal solution of oxalic acid,
and the precipitate treated with a little water. If it
dissolves, it probably consists of                        _papaverine_.


CARBONIC ACID DISSOLVES THE ALKALOID.

The substance is treated with ether, notice being taken if it dissolves,
which is evaporated at the ordinary temperature of the air so as to
prevent a loss of minute portions of the alkaloid.

_Ether dissolves the alkaloid._--If nitric acid gives
first a scarlet, then a yellow color, sulphuric acid a
yellow, changing to red and violet, and hydrochloric
acid a violet color, the alkaloid present is probably
                                                            _veratrine_.

If the above colorations are not produced, chlorine
water is added to another portion of the substance,
then ammonia; the formation of a green color, changing
to violet and turning red upon a renewed addition of
chlorine water, denotes the presence of                       _quinine_.

In case all of these tests give but negative results,
and the alkaloid is soluble in concentrated sulphuric
acid, a solution being formed which assumes a
reddish-violet tint when stirred with a glass rod
previously dipped in bromine water, the presence of
                                                             _delphine_.
is indicated.

_Ether fails to dissolve the alkaloid._--If the
substance is capable of being sublimed,[N] it consists
of                                                        _cinchonine_.

  [N] Cinchonine, when sublimed, condenses in minute brilliant
  needles.--_Trans._


_b. Ammonia produces a precipitate, which redissolves in an excess of
the precipitant, but separates out after the lapse of an hour._

The substance is treated with cold absolute alcohol
and its solubility in this menstruum noted. If it
readily dissolves, it probably consists of                    _brucine_.

The presence of this alkaloid is confirmed by applying
the following tests: (1) Nitric acid imparts a
blood-red color to the substance; (2) if treated with
sulphuric acid, it acquires a reddish tint which
subsequently changes to yellow and green; (3) chlorine
at first fails to cause a coloration, but after some
time a yellow color which afterwards changes to a red
is produced; (4) upon treating the substance with
bromine, it immediately assumes a violet tinge.

In case the alkaloid is only slightly soluble in
alcohol, there is reason to infer the presence of
                                                           _strychnine_.

The following confirmatory tests should be applied:
(1) If the substance is treated with a mixture of
sulphuric acid and an oxidizing body, such as
bichromate of potassa, binoxide of manganese, or
peroxide of lead it acquires a violet color, which
changes into red and finally passes into a clear
yellow; (2) the addition of bichloride of platinum
produces a precipitation of the hydrochlorate.

Should, however, the substance be only slightly soluble
in alcohol, and the above reactions fail to take place,
the presence of                                              _solanine_.
is indicated. In presence of this alkaloid the following
reactions will occur: (1) Upon treating the substance
with concentrated sulphuric acid, it assumes a rose
tint, which changes after some time has elapsed first to
a deep violet, then to a brown color; (2) a solution of
a salt of the alkaloid reduces gold and silver salts;
(3) the addition of oxalic acid produces a precipitate
in the aqueous and even acid solution of its salts.


_c. Ammonia fails to produce a precipitate, or redissolves permanently
the one formed._

The solubility of the alkaloid in ether is ascertained. If it be
soluble, it may consist of aconitine, atropine or codeine; if insoluble,
of emetine or morphine.

_The alkaloid is soluble in ether._--If bichloride of
platinum fails to precipitate the hydrochlorate from a
neutral solution of the alkaloid, and sulphuric acid
causes it to assume a yellow color which subsequently
changes to a reddish-violet, it probably consists of
                                                            _aconitine_.

In case bichloride of platinum causes a precipitate
and sulphuric acid fails to produce the yellow
coloration referred to above, the presence of either
atropine or codeine is indicated. In order to decide
which of these bases is present, the substance is
dissolved in pure chloric acid and the solution allowed
to spontaneously evaporate. If the alkaloid is
deposited during this operation, it probably consists
of                                                           _atropine_.

If this is not the case, there is reason to infer the
presence of                                                   _codeine_.

_The alkaloid is insoluble in ether._--If it dissolves
in acetone it probably consists of                            _emetine_.

If acetone fails to dissolve it, the presence of
                                                             _morphine_.
is indicated.

The following confirmatory tests should be applied: (1)
Upon treating the substance with nitric acid, it
acquires a blood-red color; (2) the addition of a
solution of a persalt of iron produces an evanescent
blue coloration; (3) chloride of gold is colored blue,
when treated with the alkaloid; (4) the substance
reduces iodic acid: this reduction is detected by
adding to the acid a little starch-paste, which turns
blue upon the liberation of the iodine; (5)
permanganate of potassa, if heated with the substance,
is reduced and acquires a green color.


IDENTIFICATION OF DIGITALINE, PICROTOXINE AND COLCHICINE.

It has already been remarked that in exhausting the first acid solution
with ether--previous to the neutralization, according to Otto's
method--colchicine, a weak alkaloid, digitaline, an indefinite mixture,
picrotoxine (which appears to possess the properties of an acid), and
traces of atropine, pass into solution.

The ether is evaporated on a water-bath to dryness, the residuary mass
treated with slightly warmed water and the solution filtered from the
undissolved resinous matter. The aqueous solution is next rendered
feebly alkaline by addition of soda lye, and then well agitated with
ether, until this fluid ceases to leave a residue upon evaporation. The
ethereal solution is now decanted, and the water present removed by
means of chloride of calcium. If it is evaporated, a residue containing
the _colchicine_, _digitaline_ and traces of atropine (mixed possibly
with a minute quantity of picrotoxine, which is here left out of
consideration) is obtained.

_a._ The _alkaline solution_, from which the ether has been removed, is
acidulated with hydrochloric acid and again shaken with ether. The
_picrotoxine_ present is now dissolved, and upon dehydrating (by means
of fused chloride of sodium) and evaporating the ethereal solution can
be obtained in crystals. The crystals of picrotoxine are easily
recognized by their forming in feathery tufts as well as by their length
and silky brilliancy. Should crystals fail to form in a short time, it
is advisable to take up the residue, left by the evaporations of the
ether, with slightly warmed alcohol, and to allow the latter to
spontaneously evaporate on a watch-glass, or, if the quantity of
substance is exceedingly minute, on the slide of a microscope. After
determining the form of the crystals, it should be ascertained that they
possess an intense bitter taste and exhibit the other characteristic
properties of picrotoxine. The following reaction is distinctive: If the
crystals are dissolved in an aqueous solution of soda and a few drops of
"Fehling's solution"[O] added, a reddish precipitate of cuprous oxide is
formed.

  [O] An alkaline solution of tartrate of copper, employed in the
  examination of sugar, urine, and wine.--_Trans._

_b._ Provided picrotoxine has not been found, the _ethereal solution_
obtained by agitating the alkaline fluid with ether is to be examined
for colchicine and digitaline. To this end, the residue obtained upon
evaporating the solution to dryness is taken up with water, and the
filtered fluid tested as follows: 1. It is ascertained if a drop of the
solution possesses the bitter taste of digitaline. 2. Another drop is
treated with solution of tannin; if either alkaloid be present, a
precipitate is formed. 3. Two drops of the solution are next tested: one
with tincture of iodine, the other with chloride of gold. These reagents
precipitate colchicine, but do not affect solutions of digitaline or
picrotoxine. Unfortunately traces of atropine, possibly present, would
cause the same reaction; the test therefore fails to be conclusive. 4.
Several portions of the solution are evaporated on watch crystals.
Concentrated nitric acid is added to one portion: if colchicine be
present, an evanescent violet coloration is produced, which changes to a
light yellow upon addition of water, and to a pure yellow or
reddish-orange color, if the mixture is saturated with a slight excess
of caustic alkali. 5. Another portion of the residue is dissolved in a
few drops of concentrated sulphuric acid, and the solution stirred with
a glass rod moistened with bromine water: in presence of digitaline a
violet-red color is produced. This coloration is more distinct when a
small quantity of the alkaloid and an excess of sulphuric acid are
present. 6. If a large amount of substance is at hand, the residue can
be boiled with hydrochloric acid, and the green or brownish color and
characteristic odor of digitaline produced, in case this body be
present: this, however, is not a very delicate test. 7. Finally; it is
advisable when the presence of digitaline is suspected to ascertain its
physiological action. For this purpose, a minute quantity of the
substance is placed upon the heart of a frog: in presence of the
alkaloid, the pulsations are immediately retarded, or even arrested.

       *       *       *       *       *

Although by means of the tests given above the existence of a special
alkaloid, or of one of the ill-defined substances just mentioned, may be
justly regarded as probable, its presence has not yet with certainty
been demonstrated. This is especially true in cases where the compound
possesses but few characteristic properties. When possible, the
suspected substance should be obtained in a crystaline form, and then
compared by aid of the microscope--if the small quantity present permits
of no other examination--with crystals of the pure alkaloid, prepared
under the same conditions.

In case 20 or even 10 centigrammes of substance are at hand, it is
best to convert the alkaloid into its hydrochlorate, and evaporate the
solution of this salt to dryness. The residue, after being weighed, is
dissolved in water, and a solution of sulphate of silver added. The
precipitate of chloride of silver formed is collected and carefully
weighed, in order to calculate the weight of the chlorine contained in
the hydrochlorate and consequently the molecular weight of the alkaloid.
The filtrate from the chloride of silver, which contains the alkaloid in
the state of sulphate, is treated with hydrochloric acid, to remove the
excess of silver present and the fluid then filtered. The filtrate is
next shaken with potassa and ether. Upon decanting and evaporating the
ethereal solution, a residue consisting of the alkaloid present is
obtained, which is then purified by crystallization from alcohol. An
elementary analysis of the alkaloid is now executed. _Certainty_ as to
the presence of an individual alkaloid is attainable only when the
execution of this confirmatory test is possible. The reactions
previously described can be performed with fifteen centigrammes of
substance, and this amount is sometimes contained in a cadaver. If but
one or two centigrammes are at hand, it is still possible to detect the
presence of an alkaloid; a conclusion, however, as to _which_ cannot be
arrived at, especially if the substance found is a liquid or an
amorphous body, and one that presents few distinctive properties.




III.

METHODS TO BE EMPLOYED, WHEN NO CLEW TO THE NATURE OF THE POISON PRESENT
CAN BE OBTAINED.


If poisoning has been caused by the administration of a mixture of
numerous substances and these greatly differ in their properties, it is
impossible to demonstrate in an incontestible manner the presence of
each individual poison. This contingency fortunately but seldom arises;
the criminal usually has recourse to one or two poisons, the detection
of which is possible. It must not be imagined, however, that the
presence of a poison in an organ can at once be detected with certainty
by the mere application of a few tests; because, in searching for a
substance which is absent, we may unwittingly destroy the one present,
or, at least, transform it into combinations which would not allow of a
definite conclusion as to its original condition.

In order to follow a systematic method in researches of this nature, it
is advisable to divide the materials under examination into three parts:
one portion is preserved, in order to ascertain its physiological
effects on animals, the chemical analysis having failed to give positive
results. The other portions are submitted to analysis, but with slightly
different objects in view; one is subjected to a series of tests which
are adapted, under all circumstances, to place the chemist on the track
of the poison present, and which, in some cases, may even give
conclusive and definite results. Should these tests furnish only
_indications_ of the nature of the poison, the remaining portion serves,
with the assistance of this information, to establish beyond doubt the
identity of the substance.


INDICATIVE TESTS.

Two cases may present themselves: the materials to be examined possess
either an alkaline (or neutral) or an acid reaction. As the methods to
be pursued in either of these cases differ somewhat, they will be
treated separately.


THE SUBSTANCE POSSESSES AN ACID REACTION.

The materials are mixed with water, placed in a retort provided with a
delivery-tube which dips in a solution of nitrate of silver, and heated
over a water-bath: if a _cyanide_ be present, hydrocyanic acid will be
disengaged, and a white precipitate of cyanide of silver formed: this is
examined as previously directed (_vide_ p. 50).

In case a precipitate is not produced by the above treatment, more
water is added to the retort, and the mixture boiled for about an hour,
care being taken to collect the evolved vapors in a well-cooled
receiver. The portion remaining in the retort is thrown on a filter and
the filtrate obtained united with the distillate. The residue remaining
on the filter is next washed with boiling absolute alcohol, the washings
being added to the aqueous solution. In this way, the suspected
substances are divided into soluble and insoluble portions, which are
examined separately, as directed below.


_a._ LIQUID PORTION.

If the addition of alcohol caused a precipitation of animal matters,
these are separated by filtering the solution. The filtrate is then
placed under a bell-jar over concentrated sulphuric acid until its
volume is considerably reduced. The solution may contain organic and
inorganic bases and acids. In order to detect all bodies that are
present, the following course is pursued:

(1). A current of sulphuretted hydrogen is conducted through the
solution: the precipitation of some metals, usually thrown down by this
gas, may fail to take place in this instance, owing to the presence of
organic substances; however, some metals are precipitated, even in
presence of organic compounds, and organic acids are but seldom present.
In case a precipitate is formed, it is mixed with pure silica, collected
on a filter, and treated with nitric acid. If the precipitate fails to
dissolve, it is treated with _aqua regia_. In either case, the solution
obtained is examined for metals by the ordinary methods.

(2). The solution in which sulphuretted hydrogen failed to produce a
precipitate, or the filtrate separated from the precipitate formed, is
divided into two parts: one portion is treated with ether and a solution
of potassa; the other with ether and a solution of soda. Both mixtures
are then well agitated, and notice taken if the ether dissolves any
thing: if so, the operation is repeated several times until all soluble
substances are removed. The ethereal solutions are next decanted and
united, and then submitted to the examination for alkaloids as directed
pp. 65-84.

(3). If--the above treatment giving either positive or negative
results--a precipitate insoluble in ether is formed by the addition of
potassa or soda, it is collected on a filter, washed, and dissolved in
an acid. The solution is then tested for mineral bases.

(4). In case no definite result has been obtained by the preceding
operations, one of the portions (for instance, the one to which potassa
was added) is tested for the acids possibly present in the state of
salts. The solution is divided into two parts (A and B) which are
examined separately:

PORTION A.--This is evaporated to dryness and the residue divided into
four parts which are then tested for hydrofluoric, nitric, oxalic, and
acetic and formic acids.

_a._ HYDROFLUORIC ACID.--A portion of the residue is heated in a
platinum crucible with sulphuric acid, and the crucible covered with the
convex face of a watch-crystal coated with wax in which lines have been
traced with a pointed piece of wood. If, after gently heating the
crucible for some time and removing the watch-crystal, the lines traced
in the wax are found to be etched in the glass, the substance under
examination contains a _fluoride_.

_b._ NITRIC ACID.--If this acid be present, and a second portion of the
residue is heated with sulphuric acid and copper, reddish-fumes are
evolved. Upon conducting the vapors into a solution of sulphate of iron
or narcotine, the reactions already mentioned in treating of nitric acid
take place.

_c._ OXALIC ACID.--The third portion of the residue is heated with
sulphuric acid, and the evolved gas carefully collected. It should then
be confirmed by an elementary analysis that the gas consists of equal
volumes of carbonic oxide and carbonic acid. This test is not
conclusive; it is also necessary to ascertain if the precipitate
produced by the addition of a baryta solution (_vide_: under portion
_B._) produces the same reaction, inasmuch as other organic bodies could
give rise to carbonic oxide and carbonic acid, and the danger of both
admitting the presence of oxalic acid, when it is absent, and omitting
its detection, in case it is present, would be incurred.

_d._ ACETIC AND FORMIC ACIDS.--The fourth portion of the residue is
distilled with dilute sulphuric acid. After determining that a small
portion, previously neutralized with a base, acquires a red color, upon
addition of a solution of a persalt of iron, the distillate is divided
into two parts. One portion is treated with bichloride of mercury: if
_formic acid_ be present, metallic mercury is formed, with evolution of
carbonic acid which produces turbidity in lime-water. The remaining
portion of the fluid is digested, in the cold, with an excess of
litharge: in presence of _acetic acid_, a soluble basic salt of lead,
possessing an alkaline reaction, is produced.

PORTION B.--The second portion of the solution is supersaturated with
nitric acid, and this neutralized by addition of a slight excess of
ammonia. The ammonia is then expelled by boiling the fluid, and a
solution of nitrate of baryta added. If a _precipitate_ forms, it is
collected and subsequently examined for sulphuric, phosphoric, oxalic
and boric acids as directed below. The _filtrate_ is preserved and
tested for hydrochloric, hydrobromic and hydriodic acids.

_a._ OXALIC ACID.--A portion of the precipitate produced by the addition
of nitrate of baryta is submitted to the test mentioned under the
treatment of portion _A_.

_b._ SULPHURIC ACID.--If an insoluble residue remains upon treating the
remainder of the precipitate with dilute hydrochloric acid, it consists
of sulphate of baryta and indicates the presence of _sulphuric acid_.

_c._ PHOSPHORIC ACID.--An excess of solution of alum and ammonia is
added to the portion of the precipitate dissolved in hydrochloric acid.
If phosphoric acid be present, insoluble phosphate of alumina is
precipitated. This is brought upon a filter: the _filtrate_ being
preserved and subsequently examined for boric acid. Upon boiling the
precipitate with solution of silicate of potassa, silicate of alumina is
thrown down, and phosphate of potassa remains in solution. Chloride of
ammonia is now added to the liquid--in order to eliminate the excess of
silica from the silicate--and the solution filtered. The _filtrate_ is
then tested for phosphates, by means of molybdate of ammonia (_vide_:
_detection of phosphoric acid_, p. 48).

_d._ BORIC ACID.--The filtrate from the precipitate of phosphate of
alumina is evaporated to dryness, the residue mixed with sulphuric acid
and alcohol, and the latter ignited. If the substance contains _boric
acid_, the alcohol will burn with a _green_ flame.

The _filtrate_, separated from the precipitate produced by the addition
of nitrate of baryta, may contain hydrochloric, hydrobromic and
hydriodic acids. In order to detect these compounds, some nitrate of
silver is added to the solution, and the precipitate that may form
carefully washed and decomposed by fusion with potassa. The mass is then
dissolved in water, and the solution submitted to the following tests:

_e._ HYDRIODIC ACID.--Some starch paste and nitric acid--containing
nitrous acid in solution--are added to a portion of the solution: in
presence of an _iodide_, the fluid immediately acquires a blue color.

_f._ HYDROBROMIC ACID.--In case iodine has not been detected, chlorine
water and ether are added to a second portion of the fluid, and the
mixture well agitated. If _bromine_ be present, the ether will assume a
_brown_ color. In case iodine is also contained in the fluid, and the
detection of bromine is desired, it is necessary to acidulate the
solution with hydrochloric acid, and then shake it with chloride of lime
and bisulphide of carbon. The bisulphide of carbon dissolves the iodine,
acquiring a _violet_ color, which disappears upon a renewed addition of
chloride of lime; whereas, in presence of bromine an _orange_ coloration
remains, even after the disappearance of the iodine reaction.

_g._ HYDROCHLORIC ACID.--Since the substance under examination will
already contain hydrochloric acid, it is unnecessary, in most cases, to
institute a search for this compound. Nevertheless, it may be well to
take a quantity of the solution, corresponding to a known weight of the
original substance, and precipitate the acid by adding nitrate of
silver. The precipitate formed is dried and weighed. It is then heated
in a current of chlorine, in order to completely convert it into
chloride of silver, and its weight again determined. Only in case the
amount of chloride found is very large, is it to be inferred that the
poisoning has been caused by hydrochloric acid.

_h._ HYDROSULPHURIC ACID.--(_Sulphuretted hydrogen_). If the precipitate
produced by nitrate of silver possesses a black color, it may consist of
a _sulphide_. Upon treating a portion with solution of hyposulphite of
soda, all but the sulphide of silver is dissolved. In case a residue
remains, it is calcined with nitrate of soda, and the sulphate formed
detected by adding a soluble barium salt to its solution.

Sulphates, chlorides, carbonates and phosphates are most frequently met
with in the preceding examination, and it should be carefully noticed
which of these salts exist in the greatest abundance. If acids of
comparatively rare occurrence (such as the oxalic and tartaric) are
found, their approximate amount is also to be noted. These facts,
together with the original acidity of the materials and the absence of
other toxical bodies, would lead to the conclusion that the poisoning
was caused by the reception of an acid, as well as to the identification
of the special acid used. In subsequently effecting the detection of the
poison by the determinative tests, the danger of destroying other
poisons possibly contained in the substance will be obviated, as the
question of the absence or presence of these latter will have been
previously decided.

(5). The examination for acids concluded, the various fluids which have
accumulated, and from which the acids present have been separated, are
united and the whole evaporated to dryness. The organic substances,
present in the residue obtained, are destroyed by means of nitric acid,
and the residual mass examined for _soda_. If this substance has not
been introduced into the portion of fluid examined, and is discovered in
a quantity largely in excess of the amount normally contained in the
organism, it is probable that poisoning has been caused by its
administration, and that an acid has also been given, either in order to
mask the poison, or to act as an antidote. In this case, it is necessary
to carefully search for acetic acid, as this is the substance usually
employed as an antidote for alkalies.

(6.) Whatever results have been obtained by the preceding examinations,
the portion of the fluid which has been treated with soda (_vide_ p.
87) is evaporated to dryness. The organic matters possibly present
are destroyed by means of nitric acid, or _aqua regia_, and the residue
taken up with water. The solution so obtained is then examined for
metals (including potassa, which salt has not been introduced into this
portion of the fluid in any of the preceding operations) by the usual
methods.

(7). The soluble portion of the suspected materials having been
thoroughly tested, the undissolved substances remaining on the filter
are next examined.


_b._ SOLID PORTION.

(1). The organic matter present is first destroyed by treatment with
_aqua regia_. The fluid is then evaporated to dryness, and the residue
heated until the nitric acid is entirely expelled; the escaping vapors
being collected in a cold receiver. The residue is next taken up with
water, the solution filtered, and sulphuric acid added. Should a
precipitate of sulphate of lime, sulphate of baryta or sulphate of
strontia form, it is separated from the fluid and further examined. The
filtered solution is then introduced into Marsh's apparatus, sodium
amalgam being employed for generating the hydrogen, and tested for
_arsenic_ and _antimony_ by means of the reactions previously given.

(2). Whether one of the above poisons be discovered or not, the still
acid fluid is removed from the flask, a current of chlorine conducted
through it for several hours and the solution then examined for
_mercury_ by Flandin and Danger's method. In case mercury is found it
could scarcely have originated from the metal in Marsh's apparatus, as
this would not be attacked by cold dilute sulphuric acid: however, to
remove all doubts, the test should be repeated with a portion of the
substances reserved for the examination by the determinative tests.

(3). Whatever have been the results of the above examinations, it is
still to be ascertained if the fluid, which has been successively
treated by Marsh's and Flandin and Danger's methods, does not contain
other metals. This is accomplished by means of the ordinary reactions.


THE SUBSTANCE POSSESSES A NEUTRAL OR AN ALKALINE REACTION.

The examination is conducted in precisely the same manner as in the
preceding case, excepting that the materials are first acidulated with
oxalic or tartaric acids. Particular attention should be given to the
search for soda, potassa, lime, baryta and strontia, and the
determinative tests subsequently applied according to the indications
obtained.


DETERMINATIVE TESTS.

In many instances the tests we have termed indicative become
determinative in their character. This is the case when the isolation of
an alkaloid or a metal (unless mercury be found under the circumstances
already mentioned) is accomplished; the results obtained are then
_conclusive_. If, on the other hand,--not being able to separate either
an alkaloid or a metal--upon saturating the originally acid fluid with
potassa, or soda, the salts of these bases have been found in abundance,
there is reason to _infer_ that the poisoning has been caused by an
acid; or, if, after the neutralization of the originally alkaline
solution with an acid, potassa or soda are discovered in a large
quantity, poisoning by an alkali is _indicated_.

In case the fluid is neutral, but more or less colored and odoriferous,
and iodides or bromides are detected, we may justly _suspect_ that the
poisoning has been caused by the reception of iodine or bromine.

According to the indications furnished, iodine, bromine, one, or all of
the acids, the caustic alkalies, etc., are then detected by means of the
methods to be employed in cases where the expert has a clew to the
poison present. In this manner, the presence of potassa and soda, and of
bromine and iodine, even in mixtures, is easily ascertained. It only
remains to mention the course to be pursued when suspicion exists that
poisoning has been caused by the administration of a mixture of several
acids. The suspected materials are boiled with water, and alcohol added
to the solution in order to coagulate the animal matters. The solution
is next filtered, the filtrate placed in a retort provided with a
receiver and distilled until the residual portion acquires a pasty
consistency. In this way, the acids present are separated into two
classes: (_a_) those that are sufficiently volatile to have passed into
the receiver, such as, acetic, nitric, hydrochloric and sulphuric acids
(the latter acid will only be partially volatilized); and (_b_) those
that remain in the retort. The former are detected by examining the
distillate as previously directed.

The residue remaining in the retort is treated with absolute alcohol,
the fluid filtered, and a solution of acetate of lead added to the
filtrate: sulphuric, phosphoric and oxalic acids, if present, are
precipitated. The precipitate is suspended in water and decomposed by
means of sulphuretted hydrogen. The acids contained are now set free,
and are detected by applying the tests already mentioned.

If there be reason to suspect the presence of both sulphuric and oxalic
acids, the distillation is discontinued after a short time. The two
acids are dissolved by shaking the moderately concentrated fluid
remaining in the retort with ether, and, upon evaporating the solution,
will be obtained in a state suitable for examination. Oxalic acid is
then detected by means of sulphate of lime; sulphuric by means of
oxalate of baryta.

The above examinations would fail to effect the detection of
_phosphorus_, and it is necessary to examine a separate portion of the
original substance for this body.




IV.

MISCELLANEOUS EXAMINATIONS.


DETERMINATION OF THE NATURE AND COLOR OF THE HAIR AND BEARD.

A criminal, in order to conceal his identity, may change the color of
the hair and beard by artificial means; either to a darker shade, in
case they were naturally of a light color, or, to a lighter hue, if they
were originally dark, and the chemical expert may be called upon to
detect this artificial coloration, and restore the original color of the
hair.

It may also happen, that portions of hair still adhere to the clots of
blood sometimes found on an instrument which has been employed in the
commission of a crime, and consequently the question may arise as to the
nature of the hair, whether it be human or animal.


DETERMINATION OF THE COLOR OF THE HAIR AND BEARD.

The mode of examination necessary when the hair has been blackened is
different from that used when it has been decolorized.


_The hair has been blackened._

As various methods of dyeing hair black are in use, the means of
restoring the original color differ. The following are the methods most
usually employed in dyeing:

1º. The hair is well rubbed with a pomade, in which finely pulverized
charcoal is incorporated. This preparation, which is sold under the name
of "_mélaïnocome_," possesses the disadvantage of soiling the fingers
and clothing, even for several days after its application.

2º. The hair is moistened with a dilute solution of ammonia, and a
perfectly neutral solution of a bismuth salt (chloride or nitrate) is
then applied. It is subsequently washed, and allowed to remain in
contact with a solution of sulphuretted hydrogen.

3º. The same operation is performed, a lead compound being substituted
for the bismuth salt.

4º. A mixture of litharge, chalk, and slacked lime is applied, and the
head covered with a warm cloth. The hair is afterwards washed, first
with dilute vinegar, then with the yolk of an egg.

5º. The hair is first cleansed with the yolk of an egg, and then
moistened with a solution of plumbate of lime; or,

6º. It is moistened with a solution of nitrate of silver, to which a
quantity of ammonia sufficient to dissolve the precipitate first formed
has been added.

The first method merely causes a mechanical admixture of a coloring
matter with the hair. In the four succeeding processes, a black metallic
sulphide is produced; either by the subsequent application of a solution
of sulphuretted hydrogen, or by the action of the sulphur normally
present in the hair.

In the last method, the formation of sulphide of silver doubtless
occurs; but the principal change that takes place is probably due to the
action of light, which, as is well known, decomposes the salts of
silver.

In order to restore the original color to hair which has been treated
with "_mélaïnocome_," it is only necessary to dissolve in ether the
fatty matters present, and then remove the charcoal by washing with
water.

In case the hair has been dyed by means of a bismuth or lead salt (as in
methods 2, 3, 4 and 5), it is immersed for several hours in dilute
hydrochloric acid: the metal present dissolves, as chloride, and the
original color of the hair is rendered apparent. It then remains to
detect the metal dissolved in the acid solution, in order to establish,
beyond doubt, the fact that a dye has been employed. This is
accomplished by means of the methods used for the detection of metals in
cases of supposed poisoning.

If, finally, an ammoniacal solution of nitrate of silver has been
employed to cause the coloration, the hair is immersed, for some time,
in a dilute solution of cyanide of potassium, and the fluid subsequently
examined for silver. In case a portion of the salt has been converted
into the sulphide, it will be difficult to restore the original color,
as the removal of this compound is not easily effected.


_The hair has been decolorized._

Black hair can be bleached by means of chlorine-water, the various
shades of the blonde being produced by the more or less prolonged action
of the reagent. In this case, the odor of chlorine is completely removed
only with great difficulty, and the hair is rarely uniformly
decolorized. The expert may therefore be able to observe indication that
will greatly assist him in arriving at a definite conclusion. The hair
should be carefully examined up to the roots: if several days have
elapsed since the decolorization has been performed, the lower portion
of the hair will have grown and will exhibit its natural color. No
method has yet been proposed that restores the original color to
bleached hair. It is very possible, however, that this end would be
attained by allowing nascent hydrogen to act upon the decolorized hair.
For this purpose, it would be necessary to immerse it in water
containing some sodium amalgam, and slightly acidulated with acetic
acid.


DETERMINATION OF THE NATURE OF THE HAIR.

In examinations of this character use is made of the microscope. The
hair to be examined is suspended in syrup, oil, or glycerine and placed
between two thin glass plates. Human hair is sometimes cylindrical;
sometimes flattened. It consists either of a central canal, or of a
longitudinal series of oblong cavities which contain oily coloring
matter, and possesses the same diameter throughout its entire length.
The brown hair of the beard and whiskers, medium-sized chestnut hair,
the hair of a young blonde girl, and the downy hair of a young man
possess respectively a diameter of 0.03 to 0.15; 0.08 to 0.09; 0.06; and
0.015 to 0.022 millimetres. These exhibit on the surface slightly
projecting scales, which are irregularly sinuous at the border,
separated from each other by a space of about 0.01 m.m., and are
transparent, whatever may be their color.

The hair of ruminants is short and stiff, and is characterized by
containing cavities filled with air. Wool, however, forms an exception,
as it consists of entire hairs, homogeneous in appearance and possessing
imbricated scales, which bestow upon it the property of being felted.

The hair of the horse, ox and cow never exceeds 12 m.m. in length, and
is tapering, its diameter gradually diminishing from the base. It is
perfectly opaque, and does not appear to possess a central canal; has a
reddish color, and frequently exhibits lateral swellings, from which
small filaments occasionally become detached, in the same manner as a
twig separates itself from the parent branch.


EXAMINATION OF FIRE-ARMS.

(_Proposed by M. Boutigny._)

The examination of fire-arms is sometimes useful in determining the date
at which a weapon has been discharged or reloaded. The methods used in
examinations of this nature vary, as the weapon under inspection is one
provided with a flint or an ordinary percussion lock. The value of the
tests employed is also affected by the kind of powder used; _i. e._,
whether common gunpowder, gun-cotton or white gunpowder (prepared by
mixing yellow prussiate of potassa, chlorate of potassa and sugar) has
been taken.


THE GUN IS PROVIDED WITH A FLINT-LOCK, AND WAS CHARGED WITH ORDINARY
POWDER.

In case the weapon has been wiped or exposed to moisture subsequent to
its seizure, it is impossible to form any conclusion as to the date of
its discharge, etc. It is therefore advisable, upon receiving the
weapon, to carefully wrap the lock in a woollen cloth, and to close the
barrel. The exterior of the gun is at first submitted to a careful
examination, and notice taken of the approximate thickness of any
existing rust spots. The fire-pan and adjacent portion of the barrel are
also examined by aid of a magnifying glass, especial attention being
given to the detection of traces of a moist and pulverulent incrustation
of a greyish or blackish color, formed by the combustion of the
gunpowder, and of crystals of sulphate of iron. If the weapon is loaded,
the wad is withdrawn and the color of its cylindrical portion and of the
powder, as well as the size of the ball or shot, noted.

This preliminary examination ended, the barrel and fire-pan are
separately washed with distilled water, and the washings passed through
filter paper which has previously been well washed, first with pure
hydrochloric acid, then with distilled water. The filtrate is next
divided into three portions, and these separately examined for: (1)
sulphuric acid, by addition of chloride of barium; (2) for iron, by
oxidizing the salts contained in the fluid with a few drops of nitric
acid and adding a solution of ferrocyanide of potassium, the presence of
iron being indicated by the formation of a blue coloration, or a blue
precipitate; and (3) for sulphides, by means of a solution of subacetate
of lead.

If a bluish-black incrustation is discovered on the fire-pan or on the
neighboring portions of the barrel, and both rust and crystals of
sulphate of iron are absent, and the washings, which were originally of
a light-yellow color, assume a chocolate-brown coloration upon the
addition of solution of subacetate of lead, _the gun has been discharged
within two hours at the longest_.

If the incrustation possesses a lighter color and traces of iron have
been detected in the washings, but neither rust nor crystals have been
discovered on the barrel or fire-pan, _the weapon has been discharged
more than two, but less than twenty-four hours_.

In case minute crystals of sulphate of iron and spots of rust are found,
and the washings contain iron in a considerable quantity, _the weapon
has been discharged at least twenty-four hours, at the longest ten
days_.

If the quantity of rust found is considerable, but iron is no longer to
be detected, _the discharge of the gun occurred ten days, at the longest
fifty days, previously_.

_If the weapon has been reloaded immediately after its discharge without
having been previously washed_, the portions of the wadding which have
come in contact with the barrel will possess a greyish-black color
during the first four days, the color gradually becoming lighter, until,
at the fifteenth day, it turns grey and remains so permanently. In this
case, the washings will contain sulphuric acid. The objection has been
advanced to the last test that sulphuric acid might be discovered, even
if the gun had not been discharged, if the paper of which the wadding
was made contained plaster. M. Boutigny states, however, that this
objection is untenable, if the wadding has not been moistened by the
water introduced into the barrel.

_In case the gun has been washed and dried before being reloaded_, the
cylindrical portion of the wadding possesses an ochre-yellow color up to
the first or second day, assumes a decided red hue on the days
following, and acquires a clear rusty color on the sixth day. During the
fifth day the powder also possesses a reddish appearance, owing to an
admixture of rust. Sulphuric acid is not present in the washings.

_If the weapon has been reloaded immediately after being washed_, the
wadding possesses a greenish-yellow appearance for the first few hours,
and subsequently acquires a reddish color, as in the preceding case.

_If, finally, the barrel has been washed with turbid lime-water_, rust
is still to be found and the wadding possesses the color mentioned
above. The following colorations are also to be observed in case the gun
has not been washed, or has been dried near a fire:

                         BARREL DRIED NEAR A FIRE.     UNWASHED BARREL.
  After 1 day           slight reddish yellow color  greenish yellow color.
        2 or 3 days     a little darker         "    reddish-brown     "
        4 days          a redder                "    reddish-brown     "
        5 or more days  a rusty-red             "    rusty-red.        "


THE GUN IS NOT PROVIDED WITH A FLINT LOCK.

At present weapons having flint-locks have almost entirely gone out of
use and have been superseded by the ordinary percussion gun; these
latter, in turn, are being gradually replaced by breech-loaders, charged
with or without a metallic cartridge. The indications obtained in the
preceding examinations by means of the fire-pan, will therefore
disappear; the results given by the inspection of the barrel may
possibly hold good. In regard to breech-loaders, all the useful
indications furnished by the coloration of the wadding and powder fail
to occur; the latter being enclosed either in a paper cylinder or in a
copper socket.

The fact that gun cotton and white gunpowder are occasionally made use
of, adds to the difficulty of obtaining reliable results by the mere
inspection of a weapon. White gunpowder does not oxidize the gun, fails
to give rise to any salt of iron, and possesses a white color;
gun-cotton produces distinctive indications varying with its purity.
Owing to these facts, it is evident that the method proposed by M.
Boutigny is of no real value, save in the rare instances where a gun
provided with a fire-pan, and charged with ordinary powder, is under
examination, and the question of the lapse of time since the discharge
of a weapon must remain undetermined so far as scientific tests are
concerned.


DETECTION OF HUMAN REMAINS IN THE ASHES OF A FIRE-PLACE.

This class of examinations is particularly necessary when the crime of
infanticide is suspected. As the complete incineration of a cadaver is a
long and difficult operation, it frequently occurs that bones--partially
or completely carbonized, but retaining their original form--are
discovered by the careful examination of the ashes of the fire-place in
which the combustion was accomplished.

When this is not the case and complete incineration and disaggregation
have occurred, recourse must be had to the indications furnished by a
chemical analysis. These indications are reliable, however, only when
the certainty exists that bones of animals have not been consumed in the
same fire-place; otherwise, the results obtained are entirely worthless,
the reactions given by ashes of animal bones being identical with those
produced by the ashes of a human body. Two tests are employed to detect
the presence of bones in the residue left by the combustion of animal
matter.

1. A portion of the ashes is placed in a silver crucible, heated with
potassa, and the mass afterwards treated with cold water. If animal
matter is contained in the consumed materials, cyanide of potassium will
be present in the aqueous solution. In order to detect this salt, the
fluid is acidulated with hydrochloric acid, and a solution of
persulphate of iron added: the formation of a blue precipitate indicates
the presence of the cyanide.

2. The ashes are next examined for phosphate of lime. As wood, coal, and
the other substances usually employed for heating purposes contain none
or little of this salt, its detection in a notable quantity would lead
to the inference that bones have been consumed. The ashes are allowed to
digest for twenty-four hours with one-quarter of their weight of
sulphuric acid. Water is next added to the pasty mixture, and the fluid
filtered. If phosphate of lime be present, it is converted by this
treatment into a soluble acid phosphate, which passes into the filtrate.
Upon adding ammonia to the filtrate, a precipitate of neutral phosphate
of lime is formed, neutral phosphate of ammonia remaining in solution.
The fluid is again filtered, the filtrate acidulated with nitric acid,
and then boiled with a solution of molybdate of ammonia likewise
acidulated with nitric acid: in presence of a phosphate, a yellow
precipitate, or at least a yellow coloration of the fluid, will be
produced. It has been stated that the disengagement of sulphuretted
hydrogen, upon treating the ashes with sulphuric acid, is an indication
that the combustion of a human body has occurred; this reaction is,
however, valueless, inasmuch as coal and certain vegetable ashes
likewise evolve the gas when subjected to the same treatment.


EXAMINATION OF WRITINGS.

Contracts, checks, etc., are frequently altered with criminal intent,
either by erasing the portion of the writing over the signature and
substituting other matter, or by changing certain words, in order to
modify the signification of a sentence.

Writings are altered either by erasure or by washing. Erasure, although
more easily executed, is seldom employed, as it renders the paper thin
in places, and in this way leaves effects apparent even to the naked
eye, and, although the original thickness can be restored by application
of sandarac or alum, these substances possess properties differing from
those exhibited by paper, and may, moreover, be completely removed, thus
exposing the thinning of the paper.

In case washing by means of chlorine has been resorted to, the
sizing--which renders the paper non-bibulous, and which is only with
difficulty replaced--may have been removed. Formerly paper was sized by
immersion in a solution of gelatine; at present, however, a soap of
resin, or wax, and alumina (a little starch being added) is more
commonly used. In the latter case, the sizing is less easily removed by
the action of water than when the gelatine preparation is employed; the
detection of its attempted restoration is also a matter of less
difficulty, as gelatine would be employed for this purpose, and this
body possesses properties different from those exhibited by the
substances normally contained in paper: iodine, for instance, which
imparts a yellow color to gelatine, turns starch violet-blue. In order
to detect the alteration of a writing, the following examinations are
made:

1º. The paper is carefully examined in all of its parts, and in various
positions, by aid of a lens. In this way, either thinned points, caused
by erasure, or remaining traces of words, may possibly be discovered.

2º. The paper is next placed upon a perfectly clean piece of glass, and
completely and uniformly moistened with water. The glass is then
removed, and the transparency of the paper examined by aid of a lens.
When uniform transparency is exhibited, and certain portions are neither
more transparent nor more opaque than the rest of the paper, it is
probable that erasure has not been attempted. If, on the other hand,
opaque points are observed, it is almost certain that letters have been
erased, and sandarac, which is not affected by water, subsequently
applied. In case transparent points are detected, there is reason to
suspect that words have been removed, and the spots either left intact
or afterwards coated with a substance soluble in water, such as alum.

3º. The paper is dried and the above operation repeated with alcohol of
87 per cent. Indications may now be observed which failed to occur in
the treatment with water; as well as these latter confirmed. As alcohol
dissolves sandarac, the points that formerly appeared opaque may now
become transparent.

4º. The paper is again dried, then placed under a sheet of very thin
silk-paper, and a warm iron passed over it. This operation frequently
causes the reappearance of words that have been partially obliterated.
It is also advisable--as suggested by _M. Lassaigne_--to expose the
paper to the action of iodine vapors. If alteration has not been
attempted, the paper will acquire an uniform color; yellow, if sized
with gelatine; violet blue, if sized with the mixture of soap, resin and
starch. When, on the contrary, a subsequent sizing of gelatine has been
applied in order to mask the alteration--the paper having been
originally sized with the above mixture--it will assume in some portions
a yellow, in others a violet-blue color.

5º. It is ascertained whether the paper possesses an acid reaction. If
so, its acidity may result from the presence of hydrochloric acid, in
case the paper was washed with chlorine, or of other acids. Alum, used
to disguise erasure, would also cause an acid reaction. The mere
detection of acidity is, in itself, of little importance, as, in the
manufacture of paper, the pulp is bleached by means of chlorine, and
this reagent may not have been entirely removed by washing. If, however,
the paper is acid only in certain spots, and these points produce a red
coloration upon blue litmus paper, having the form of letters, the
indication is of value. In order to ascertain if this be the case, it is
advisable, before wetting the paper, to slightly press it upon a sheet
of moist litmus paper: the acid spots will then leave a reddish trace
upon the latter.

6º. The manuscript under examination is again spread upon a glass-plate,
and a solution of tannin (or preferably, a solution of ferrocyanide of
potassium containing one per cent. of the salt, and acidulated with
acetic acid) applied by means of a brush. If the original writing was
executed with ordinary ink (which has as its base tannate of iron), and
the washing has been but imperfectly performed, it is quite possible
that a blue coloration will be produced by the action of the
ferrocyanide. It is, however, often necessary to apply the above
reagents several times before the original writing becomes apparent;
indeed, in some cases months have elapsed before the reaction has
occurred.

In case the alteration or destruction of the document is feared in the
above test, it is well to previously provide the court with a certified
copy, and then proceed with the examination.

7º. If the paper possesses a friable appearance, it has possibly been
washed with sulphuric acid. This property may however originate from
other causes, and the presence of the acid should be confirmed by
washing the document with distilled water, and adding a solution of
chloride of barium to the washings. The precipitate should form in a
considerable quantity, as a slight cloudiness could be due to sulphates
contained in the water used in the preparation of the pulp.

If much sulphuric acid be present, it may be so concentrated by heating
as to cause the carbonization of the paper.

8º. It is also well, should washing with sulphuric acid be suspected, to
ascertain, by aid of a lens, if the filaments on the surface of the
manuscript possess an inflated appearance. This would be caused by the
escape of carbonic acid, originating from the action of sulphuric acid
upon the carbonates contained in the water used in the manufacture of
the paper.

9º. Old ink is more difficult to remove than new, and it is therefore
sometimes possible to cause the reappearance of old writings, over which
words have been subsequently written. For this purpose, a solution
containing 50 per cent. of oxalic acid is applied with a fine brush over
the suspected points. As soon as the ink disappears, the acid is
immediately removed by washing with water, and the paper dried. Upon now
repeating the operation, the presence of a former writing may be
detected after the complete disappearance of the words last written.

10º. According to _M. Lassaigne_, when the same ink has not been used
throughout a document, washing with dilute hydrochloric acid will
demonstrate the fact. This acid, while causing the gradual obliteration
of characters written with ordinary ink--the shade of the paper not
being altered--produces a red color, if ink containing log-wood has been
employed, and a green coloration, in case the ink used contained
Prussian blue.

The expert may possibly be called upon to give evidence as to the
existence of a "_trompe-l'oeil_;" as was the case in the trial of _M. de
Preigne_, which took place at Montpelier in 1852. A "_trompe-l'oeil_"
consists of two sheets of paper, glued together at the edges, but having
the upper sheet shorter than the other which therefore extends below it.
This species of fraud is executed by writing unimportant matter on the
uppermost sheet, and then obtaining the desired signature, care being
taken that it is written on the portion of the paper projecting below.
The signature having been procured, it is only necessary to detach the
two sheets in order to obtain a blank paper containing the signature,
over which whatever is desired can be inserted. The trial referred to
above, was in reference to a receipt for 3,000 francs. The expert, upon
placing pieces of moistened paper upon the suspected document, noticed
that they adhered to certain points, and that these formed a border
around the paper but passing _above_ the signature. The fraudulency of
the act was thus established, and so recognized by the court, although
the accused was acquitted by the jury.

Numerous means have been proposed, in order to render the falsification
of documents a matter of difficulty. The most reliable of these is the
use of "Grimpe's safety-paper," containing microscopic figures, the
reproduction of which is impossible. Unfortunately, up to the present,
the government has adopted methods less sure.


EXAMINATION OF WRITINGS IN CASES WHERE A SYMPATHETIC INK HAS BEEN
USED.

Sympathetic inks are those which, although invisible at the time of
writing, become apparent by the application of certain agents. They are
of two classes: those which are rendered visible by the mere application
of heat, such as chloride of cobalt, or the juice of onions; and those
which are brought out only by the action of a reagent. The inks of the
second class most frequently used are solutions of acetates of lead, and
other metals which give a colored sulphide when treated with
sulphuretted hydrogen. Characters written with a solution of
ferrocyanide of potassium acquire a blue color, if washed with a
solution of perchloride of iron. It is scarcely necessary to add that
the latter solution can be used as the ink, and the ferrocyanide as the
developer.

When the presence of characters written with a sympathetic ink is
suspected, the document is examined as follows:

1. The paper is at first warmed: if the ink used is of the first class,
the characters will now become legible; otherwise the examination is
continued as below.

2. The paper is exposed to the action of steam, in order to moisten the
ink present (care being taken to avoid dissolving the characters), and a
current of sulphuretted hydrogen allowed to act upon it. If the ink used
consists of a lead, bismuth, or gold salt, a black coloration will
ensue; if salts of cadmium or arsenic were employed, the characters will
acquire a yellow color; if, finally, a salt of antimony was used, a red
coloration will be produced.

3. If no coloration was caused by the action of sulphuretted hydrogen,
it is probably that either a solution of ferrocyanide of potassium or a
persalt of iron has been resorted to. Each of these solutions is
separately applied on a small portion of paper by means of a brush, and
notice taken if the characters become visible. The solution that
produced the change is then applied over the entire sheet.

4. In case only negative results were obtained in the preceding
operations, it must not yet be concluded that a sympathetic ink has not
been used, although we are left without further recourse to chemical
tests. Numerous organic compounds may have been resorted to, the
detection of which is almost impossible; moreover, if a mistake was made
in regard to the preparation supposed to have been used, the reagents
employed for its detection may render the discovery of another ink
absolutely impossible. It is therefore often necessary to apply
mechanical tests. For this purpose, the paper is spread upon a glass
plate, uniformly moistened with water, and a second plate placed over
it: if the characters were written with a pulverulent substance
suspended in water or mucilage, they may often be observed upon
examining the transparency of the paper. In case the substance used is
both colorless and soluble, the detection of the written characters will
be more difficult; still, indelible traces may possibly have been left
by the pen. If, however, the ink employed is a colorless and transparent
organic compound of rare occurrence, and was applied with a fine
pencil-brush which failed to affect the paper, it must be acknowledged
that little or nothing can be definitely determined as to its presence
or absence.


FALSIFICATION OF COINS AND ALLOYS.

In all civilized countries a fixed standard for coins and precious
alloys is established by law, in order to prevent the perpetration of
frauds which would be of serious injury to the public welfare. The
substitution of coins consisting of an alloy inferior in value to the
standard fixed by law, is too advantageous a fraud not to be often
attempted.

Coins are most frequently altered by _clipping_; by _stuffing_, that is,
by boring the coin and inserting an alloy of small value; by _doubling_,
which operation consists in covering its face with two thin laminæ taken
from a genuine coin; and by applying a coating of gold or silver by
means of electro-plating.

In order to ascertain if a coin has been counterfeited, its weight
should at first be determined. If it has been clipped, or consists of an
alloy possessing a density less than that of silver or gold, the fact is
immediately demonstrated by its decreased gravity.

The coin is further tested by throwing it down upon a hard substance:
gold and silver give a ringing sound, whereas the majority of other
metals produce a dull sound.

The result obtained by this latter test often fails to be reliable. A
skilful counterfeiter may prepare an alloy equally sonorous and heavy as
silver or gold; in fact, _M. Duloz_ exhibited to the author an alloy,
prepared by him, possessing the density, sonorousness and lustre of
silver; the composition of which, for obvious reasons, has not been
published.

In instances of this nature the fusibility of the coin should be
determined, and the result obtained compared with the melting point of
the legal alloy, or, this failing, a chemical analysis executed. In
order to perform the latter test, the coin under examination is boiled
with nitric acid: all metals are dissolved, with exception of gold and
platinum, which remain unaltered, and tin and antimony, which are
converted respectively into metastannic and antimonic acids. The fluid
is filtered, the insoluble residue well washed, and then boiled with
hydrochloric acid, which dissolves the metastannic and antimonic acids.
The solution is again filtered, and the second residue dissolved in
_aqua regia_. The metals dissolved in the several filtrates are then
detected, either by the processes previously given for the detection of
metallic poisons, or by the more complete methods contained in works on
chemical analysis. This qualitative test is, however, insufficient, in
case the falsification consisted in merely diminishing the proportions
of the valuable metals contained in the alloy, without changing its
qualitative composition: it is then necessary to execute a quantitative
estimation of the metals present. As this operation requires
considerable practice and the methods employed are to be found in all
treatises on quantitative analysis, we will not reproduce them here.


EXAMINATION OF ALIMENTARY AND PHARMACEUTICAL SUBSTANCES.

We will next enumerate the methods employed in the detection of the
principal adulterations to which flour, bread, oils of seeds, milk,
wines, vinegar and the sulphate of quinine are subjected. These
researches, united with those preceding, fail to embrace all the diverse
examinations which the chemical expert may be expected to execute; but
we do not claim to foresee all the contingencies that may arise, and
will describe the steps to be pursued in instances which are
anticipated, at the same time indicating general methods applicable to
cases not here included.


FLOUR AND BREAD.

The adulterations to which flour and bread are exposed usually consist
in adding damaged or an inferior grade of flour to wheaten flour, or in
disguising the presence of a poor quality of flour by the addition of
mineral substances, such as: plaster, chalk, lime, alum, and sulphate of
copper.

Good flour has a white color, possessing a slightly yellow tinge, but is
entirely free from red, grey or black specks. It is soft to the touch
and adheres to the fingers, acquiring, when compressed in the hand, a
soft cushion-like form. If mixed with water, it forms an elastic,
homogeneous, but slightly coherent dough, which can be extended out in
thin layers.

Flour of an inferior quality possess a dull white color, and does not
assume the cushion-like condition mentioned above, when pressed in the
hand, but escapes between the fingers: the dough formed is of a poorer
quality.

Flour which has been damaged by moisture has a dull or reddish-white
hue, and possesses a mouldy, or even a noxious, odor, as well as a
bitter and nauseous taste which produces a marked acid sensation in the
throat. Occasionally the presence of moisture causes the growth of
_fungi_, the introduction of which in the digestive organs would cause
serious results.

The constituents of pure flour are:

_Gluten._

_Starch_, in the proportion of 50 to 75 per cent.

_Dextrine_, in the proportion of several per cent.

_Glucose_, in the proportion of several per cent.

_Salts_, remaining in the ash obtained by the calcination of the flour,
in a proportion not exceeding 2 per cent.

_Water_, of which it loses 12 to 15 per cent., at the heat of a
water-bath, and 15 to 20 per cent., at a temperature of 160°.

_Bran_, (ligneous and fatty matter,) in a very small proportion, when
the flour has been properly bolted.

In the process of bread-making, the gluten undergoes fermentation by
the action of the leaven and liberates carbonic acid, which causes the
dough to become porous and swell up, or, as it is termed, to _rise_.
Bread contains the same substances as flour, but gluten and starch are
present in a state that does not admit of their separation by mechanical
means, and glucose, if present at all, exists in a smaller quantity: the
proportion of dextrine and water is, on the other hand, considerably
increased. The bread of the Paris city bakeries contains 40 per cent. of
water--the crumb, which forms 5/6 of the weight of the bread, containing
45 per cent.; the crust, which constitutes the remaining 1/6, containing
15 per cent. In army bread 43 per cent. of water are contained--the
crumb, which constitutes 4/5 of the weight of the bread, holding 50 per
cent.; the crust which forms the remaining 1/5, containing 15 per cent.

The addition of common salt naturally increases the proportion of ash
left upon calcining bread.

Water is contained in stale bread in the same quantity as in fresh
bread; but exists in a modified molecular condition: upon heating stale
bread, it acquires the properties of fresh bread.

The following substances are used in the adulteration of wheaten
flour:[P]

Potato-starch.

Meals of various grains (rice, barley, corn, oats and rye).

Vegetable meals, (beans, horse-beans, kidney-beans, peas, vetch,
lentils, etc.).

Darnel meal.

Buckwheat flour.

Linseed-meal.

Mineral substances (plaster, chalk, lime, alum, and sulphate of copper).

  [P] Most of the substances here enumerated are rarely, if ever, used
  for the adulteration of flour in this country. The analyst should,
  however, give attention to the examination for such salts as alum,
  sulphate of copper, plaster, kaolin, etc.--_Trans._

In order to detect these substances, the gluten, the starch, and the ash
are separately examined.


_a._ EXAMINATION OF THE GLUTEN.

In order to separate the gluten, two parts of the flour to be examined
and one part of water are mixed into a paste, and this is placed in a
fine linen sack, in which it is kneaded under a stream of water so long
as the washings have a turbid appearance: these are preserved. The
gluten obtained from good wheaten flour possesses a light-yellow color;
emits a stale odor; and spreads out, when placed in a saucer. In case
the flour has been too strongly heated in the grinding, or otherwise
badly prepared, the gluten is granulous, difficult to collect in the
hand, and somewhat resembles flint-stone in appearance.

Gluten prepared from a mixture of equal parts of wheat and _rye_ is
adhesive, blackish, without homogeneousness, spreads out more readily
than pure wheaten gluten, separates easily and adheres somewhat to the
fingers.

Gluten obtained from a mixture of wheat and _barley_ is non-adhesive, of
a dirty reddish-brown color, and appears to be formed of intertwined
vermicular filaments.

Gluten formed from a mixture of equal parts of wheat and _oats_ has a
blackish-yellow color and exhibits, at the surface, numerous small white
specks.

The gluten from a mixture of wheat and _corn_ has a yellowish color, is
non-adhesive, but firm, and does not readily spread.

Gluten prepared from a mixture of wheat and _leguminous flour_ is
neither cohesive nor elastic, and, if the proportion of the latter
present be considerable, can be separated and passed through a sieve,
like starch.

The gluten obtained from a mixture of equal parts of wheat and
_buckwheat_ flour is very homogeneous, and is as easily prepared as the
gluten from pure wheaten flour. It possesses when moist a dark-grey
color; which changes to a deep black upon drying. The proportion of
gluten in flour is exceedingly variable: good flour contains from 10 to
11 per cent. of dry gluten; poor flour from 8 to 9 per cent. of moist
gluten, equal to about one-third of its weight of the dry compound.


_b._ EXAMINATION OF THE STARCH.

The washings of the flour are allowed to stand for some time in a
conical-shaped vessel. As soon as the amylaceous matter has entirely
settled to the bottom of the vessel, the greater portion of the water is
decanted, and the residual mass brought upon a small filter and allowed
to dry. The residue is then examined for potato and rice starch.

_Potato starch._ The grains of potato starch are much larger than those
of wheaten starch. If a portion of the residue mentioned above is
crushed in an agate mortar, the granules of potato starch present are
ruptured, and their contents liberated; the wheaten starch remaining
unaltered. The mass is then taken up with water, and the fluid filtered.
If potato starch be present, the filtrate will acquire a blue color upon
addition of an aqueous solution of iodine; otherwise, a yellow or
violet-rose coloration is produced. It is necessary to avoid crushing
the residue for too long a time, as the granules of wheaten starch would
also become ruptured by prolonged comminution.

Besides the difference presented by potato starch in the size of the
granules in comparison to those of wheaten starch, the former swell to
ten or fifteen times the volume of the latter, when treated with a
solution of potassa: wheaten starch granules are not affected by the
treatment, if the solution used does not contain more than 2 per cent.
of the salt. The results obtained by the above operation should be
confirmed by a microscopic examination.

A portion of the residue is moistened with solution of iodine, then
carefully dried, and placed on the slide of a microscope. The mass is
next moistened with a solution containing 2 per cent. of potassa, and
examined. The addition of iodine causes the potato starch granules to
acquire a blue color, and renders their shape and volume more easily
perceptible; thus allowing the two varieties of starch to be readily
distinguished. Fig. 13 represents the relative size of the granules as
observed under the microscope.[Q]

  [Q] It may be added, as a distinguishing property, that granules of
  potato starch, when viewed in polarized light by aid of a Nicol's
  prism, present a well-defined black cross, corresponding to the hilum;
  wheaten-starch fails to exhibit this phenomenon.--_Trans._

  [Illustration: Fig. 13.]

The presence of potato starch in bread is also detected by crushing a
small portion of the sample under examination on the glass, and then
adding a few drops of the alkaline solution.

_Rice and Corn._--If rice or corn meal have been mixed with the flour,
angular and translucent fragments (Fig. 14) are observed in the
microscopic examination. Corn meal acquires a yellow color, if treated
with dilute potassa solution.

  [Illustration: Fig. 14.]


MISCELLANEOUS TESTS.

_Linseed and rye meals._--If linseed meal is moistened with an aqueous
solution containing 14 per cent. of potassa and examined under the
microscope, numerous minute characteristic granules, smaller than the
grains of potato-starch, are observed. These possess a vitreous
appearance, sometimes a reddish color, and usually form in squares or
very regular rectangles. The test is equally applicable to bread. The
detection of linseed and rye meals is simultaneously effected by
exhausting the suspected flour with ether, then filtering the solution
and allowing it to evaporate. If the flour contains rye, the oil left by
the evaporation, when heated with a solution of mercury in concentrated
nitric acid, is converted into a solid substance having a fine red
color; but it remains unaltered, if entirely due to linseed. In case the
oil becomes solidified, the mercury salt present should be removed by
washing with water, the residue taken up with boiling alcohol of 36° B.
and the solution filtered: upon evaporating the alcoholic filtrate, a
residue is obtained consisting of the linseed oil present.

_Buckwheat._--Flour adulterated with buckwheat is less soft to the
touch, does not pack as easily, and passes more readily through a sieve
than pure wheaten flour. It presents, here and there, blackish
particles, due to the perisperm of the grain, and has a dirty-white
color. As previously remarked, the gluten obtained from a mixture of
buckwheat and wheaten flour possesses a grey or even a black color. The
starch furnished by buckwheat flour exhibits polyhedral agglomerations,
analogous to those presented by corn.

_Darnel._--The use of darnel in the adulteration of wheaten flour may
give rise to serious sanitary results. To effect its detection, the
flour to be examined is digested with alcohol of 35° B.: if the flour be
pure, the alcohol remains limpid: it acquires a straw-yellow tint, due
to traces of bran present, but--although a peculiar resin may be
dissolved--the solution does not possess a disagreeable taste. When, on
the contrary, darnel is present, the alcohol assumes a green tint, which
gradually deepens, and possesses a bitter and nauseous taste; the
residue, left by the evaporation of the tincture to dryness, has a
greenish-yellow color, and a still more disagreeable flavor than the
alcoholic solution.

_Legumens._--Leguminous meals cannot be added otherwise than in small
proportions to wheaten flour, owing to the rapidity with which they
change the properties of the latter, and communicate to it their
characteristic odor--noticeable upon treating the flour with a little
boiling water. Their presence is also easily detected by the distinctive
properties of the vegetable itself, and by the appearance of the
amylaceous residue in the microscopic examination. In order to decide as
to the presence of legumens, the washings containing the starchy matter
of the flour, after the particles of gluten present have been separated
by passing the fluid through a silk sieve, are divided into two
portions. One portion is allowed to undergo fermentation, at a
temperature of 18° to 20°: in case leguminous substances are not
present, lactic fermentation occurs and the odor of sour milk is alone
perceptible; if, on the other hand, legumens are contained in the fluid,
rancid fermentation takes place, and an odor is emitted resembling that
of decayed cheese. The remaining portion of the washings, after being
decanted from the residue of amylaceous matter, is filtered and
evaporated until a yellowish translucent pellicle appears upon its
surface. The fluid is then again filtered from the coagulated albumen
common to all flours, and the leguminous substances present coagulated
by the addition, drop by drop, of acetic acid.

The leguminous deposit produced appears white and flaky; when examined
under the microscope, it presents lamilla emarginated at the border; it
is odorless and tasteless; when dried, it assumes a horny appearance; it
is insoluble, both in water and alcohol, and does not become gelatinous
when treated with boiling water; it is readily soluble in potassa and
other alkaline solutions, from which it is precipitated upon addition of
nitric, hydrochloric, acetic, oxalic, and citric acids; upon protracted
boiling in water, it loses its property of being soluble in ammonia. The
above tests having been applied, the residue containing the starch is
next examined. For this purpose, a small portion is moistened with a
little water, a few drops of iodine solution added, and the mixture
placed on the side of the microscope: the bluish grains contained in the
polyhedral and cellular envelope (Fig. 15) are easily recognized. The
mixture on the glass may also be treated with an aqueous solution of
potassa (containing 10 per cent. of the salt), or with dilute
hydrochloric acid: these reagents dissolve the starch present, leaving
the reticulated tissue intact. Should this examination fail to give a
definite result, the remaining portion of the amylaceous residue is
subjected to a sort of levigation, and the part most slowly deposited
separated. In this portion the reticulated tissues of the leguminous
substances present are contained, and, as they are comparatively free
from foreign matters, their identification is a matter of comparative
ease. In case the presence of reticulated tissue is indicated, it is
still necessary to apply confirmatory chemical tests.

  [Illustration: Fig. 15.]

Meals prepared from beans, horse-beans, and lentils, contain a tannin
which imparts a green or black color to salts of iron. The coloration is
rendered very sensitive if a rather considerable quantity of the flour
to be examined is passed through a silk sieve, and the remaining bran
treated with a solution of sulphate of iron (_ferrico-ferrous_
sulphate): the reaction immediately occurs, even if the sample contains
but 10 per cent. of bean meal. The meals of horse-beans and of vetches
acquire a red color, when exposed to the successive action of nitric
acid and of ammonia vapors. In order to apply this test, the suspected
flour is placed upon the edge of a capsule containing nitric acid, the
latter heated, and, as a yellow coloration appears, the acid removed and
replaced by ammonia. The capsule is then set aside: if the flour is
adulterated with either of the above vegetables, reddish spots, which
are easily perceptible by aid of a magnifying glass, are soon produced.

In case bread is to be examined, it is exhausted with water, the fluid
passed through a sieve, the upper layer decanted, then evaporated, and
the residue taken up with alcohol. The tincture so obtained is
evaporated, and the second residuum treated with nitric acid and
ammonia, as directed above. When meals prepared from beans, vetches, or
lentils are heated on a water-bath with hydrochloric acid, diluted with
three to four times its volume of water, a cellular tissue, possessing
the color of wine-dregs, remains behind; flours of wheat, peas, and
kidney-beans leave a colorless residue, when subjected to the same
treatment.

Finally; the grains of the starch (_fecula_) of legumens possess a
volume about equal to that of potato granules, and exhibit either a
longitudinal furrow in the direction of their longer axis, or a double
furrow arranged in a star-like form.


_c._ EXAMINATION OF THE ASH.

Leguminous substances, and more particularly mineral salts, are detected
by the examination of the ash left upon the incineration of the flour.

_Detection of Legumens._--Pure wheaten flour furnishes an ash consisting
of about 2 per cent. of its weight; whereas meals of legumens leave from
3 to 4 per cent. of their weight in ash. This difference is, however,
too slight to furnish conclusive results; the analysis of the ash is
also necessary. The ash of wheaten flour is non-deliquescent, dry,
semi-fused, and chiefly consists of phosphates of potassa, soda,
magnesia and lime, of sulphates, and of silica. The solution obtained by
treating the ash with water has an alkaline reaction. The phosphates of
the alkalies, present in the ash of wheat, exist in the state of
pyrophosphates, and, as chlorides are absent, the addition of nitrate of
silver to the aqueous solution of the ash produces a white precipitate,
consisting entirely of pyrophosphate of silver, which is not affected by
exposure to the light.

The ash of leguminous meals is deliquescent and soluble in water,
forming a _strongly_ alkaline solution, which contains both chlorides
and _neutral_ phosphates. The latter give a clear yellow precipitate
with nitrate of silver. Upon adding a solution of this salt to the
aqueous solution of the ash, a _pale_ yellow precipitate, which turns
violet if exposed to the light, is therefore produced.

_Detection of mineral substances._--The principal mineral substances,
that are fraudulently added to flour, are ground calcined bones, sand,
lime, plaster, alum, and sulphate of copper. The two last named salts
are almost invariably added in small quantities; alum renders the flour
white, even when used in the proportion of one per cent.; sulphate of
copper is added to impart a good appearance to bread made from a damaged
flour.

_a. Ground bones_ (carbonate and phosphate of lime).--The washings of
the gluten are placed in a conical vessel, and, after some time has
elapsed, the clear supernatant fluid is removed by means of a syphon, a
conical shaped deposit remaining on the bottom of the vessel: two hours
later, the fresh layer of fluid that has formed is removed with a
pipette. As soon as the residue becomes nearly solid, it is detached
from the vessel, placed upon a fragment of plaster, and allowed to dry.
The bones, being heavier than the amylaceous substances, are to be found
in the apex of the cone formed by the residue. This is detached, and
incinerated: in case the ash obtained contains phosphate and carbonate
of lime, the addition of hydrochloric acid will cause effervescence,
and, upon adding ammonia to the acid solution, a white precipitate will
be formed. If the solution is then filtered and oxalate of ammonia added
to the filtrate, a precipitate will be produced which, when heated to
redness, leaves a residue of caustic lime possessing an alkaline
reaction.

_b. Sand._--As this substance possesses a much greater specific gravity
than the usual constituents of flour, it is only necessary, in order to
accomplish its separation, to repeatedly stir the flour with water, and
remove the deposit at first formed, which, if consisting of sand, will
be insoluble in acids, and will grate, when placed between the teeth.

_c. Carbonates of lime and magnesia; vegetable ashes._--Carbonic acid
is always evolved, upon treating flour with hydrochloric acid. If the
base present be calcium, upon adding oxalate of ammonia to the filtered
solution--which has previously been neutralized with ammonia--a white
precipitate, possessing the properties mentioned above, will be formed;
in case the base is magnesia, the addition of oxalate of ammonia will
fail to cause a precipitate, but upon adding solution of phosphate of
ammonia to the fluid a granular precipitate of phosphate of ammonia and
magnesia is produced; if, finally, the flour contains vegetable
ashes--_i. e._ carbonates of the alkalies--bichloride of platinum will
produce in the acid solution a yellow precipitate: the addition of
vegetable ashes, moreover, would render the ash of the flour
deliquescent and very strongly alkaline.

_d. Lime._--In presence of lime, carbonic acid produces a white
precipitate, when conducted into the filtered aqueous extract of the
flour.

_e. Plaster._--The flour is boiled with water acidulated with
hydrochloric acid, the fluid filtered, and lime detected in the filtrate
by means of ammonia and oxalate of ammonia. The presence of sulphuric
acid is indicated by the formation of a precipitate insoluble in acids,
upon addition of solution of chloride of barium. Upon calcining the
flour without access of air, sulphate of lime is converted into the
corresponding sulphide: the residue of the calcination, when treated
with hydrochloric acid, evolves sulphuretted hydrogen, and the lime
present in the filtered acid solution is likewise precipitated by the
addition of ammonia and oxalate of ammonia.

_f. Alum._--A portion of the flour to be examined is treated with water,
the fluid filtered, and the filtrate divided in two portions: in one,
sulphuric acid is detected by means of chloride of barium; in the other,
alumina by adding a solution of potassa, which gives with its salts a
white gelatinous precipitate, soluble in an excess of the reagent.[R]

  [R] If the detection of alum in bread is desired, a portion of the
  crumb is incinerated in a platinum dish, the ash is treated with
  concentrated hydrochloric acid, the filtered solution evaporated to
  dryness, and the residue treated with hydrochloric acid, which now
  leaves the silica present undissolved. The acid solution is then
  filtered, nearly neutralized with carbonate of soda, and an alcoholic
  solution of potassa added in excess. The earthy phosphates present are
  now precipitated, alumina remaining in solution. The use of aqueous
  potassa in this case--as well as in the case mentioned in the text--is
  not advisable, as it is seldom entirely free from alumina. Upon
  slightly acidulating the alkaline filtrate with hydrochloric acid, and
  adding carbonate of ammonia, the alumina present is precipitated, and
  may be dried and tested by means of the reaction with nitrate of
  cobalt before the blow-pipe.

  In the quantitative estimation of alumina, the phosphoric acid
  usually present in the precipitate should be removed. This is done by
  dissolving the precipitate in nitric acid and immersing a piece of
  metallic tin in the boiling solution: phosphoric acid is thrown down
  as a mixture of stannic oxide and phosphate, and the alumina is then
  precipitated as usual by carbonate of ammonia.--_Trans._

_g. Sulphate of copper._--About 200 grammes of the bread under
examination are incinerated; the ash treated with nitric acid; the
mixture evaporated until it acquires a sticky consistence, and the mass
then taken up with water. The aqueous solution is next filtered; an
excess of ammonia and several drops of solution of carbonate of ammonia
added; the fluid again filtered, the filtrate slightly acidulated with
nitric acid, and divided into two parts. It is then ascertained if
sulphuretted hydrogen produces in one portion of the solution a brown
precipitate of sulphide of copper, and if solution of ferrocyanide of
potassium produces in the other a reddish-brown precipitate of
ferrocyanide of copper.[S]

  [S] According to Wagner, if the ash, obtained by incinerating the
  adulterated bread, is washed with water, shining spangles of metallic
  copper are separated.--_Trans._


FIXED OILS.

Olive oil designed for table use is frequently adulterated with the oils
of poppy, sesamé, cotton-seed, pea-nuts, and other nuts; olive oil,
intended for manufacturing purposes, is often mixed with colza and nut
oils.

The tests used are of a rather unsatisfactory character. In all
instances, when the chemist is called upon to pronounce as to the
adulteration of an oil, it is necessary to execute comparative
experiments with the pure oil, and with admixtures arbitrarily prepared:
it is only when this is done that the indications obtained are of value.


EXAMINATION OF OLIVE OIL INTENDED FOR TABLE USE.

_a._ The density of the oil is determined by means of a hydrometer
(_oleometer_) provided with a scale giving the densities from 0.8 to
0.94, for the temperature of 15.° Pure olive oil possesses a specific
gravity of 0.917; poppy oil one of 0.925; a mixture of the two, an
intermediate density. Since the fixed oils are not definite chemical
compounds, this test is seldom conclusive.

_b._ Two or three cubic centimetres of concentrated nitric acid,
containing nitric peroxide in solution (or a solution of mercury in
strong nitric acid), are added to the oil to be examined, as well as to
a sample of pure olive oil. The two samples are then allowed to stand in
a room where the temperature does not exceed 10.° The _oleine_ of the
olive oil is converted into solid _elaidine_, and the mixture after some
time becomes sufficiently thick to remain in the vessel upon inversion.
If the sample under examination is free from adulteration, it will
solidify at the same time as the pure oil; whereas, the presence of one
per cent. of poppy oil, or of other drying oils, suffices to retard the
solidification for forty minutes.

_c._ Fifteen grammes of the oil are mixed in a glass vessel with the
same amount of strong sulphuric acid, the temperature of the two liquids
being previously observed. The mixture is stirred with a thermometer,
and the maximum temperature noted: pure olive oil produces an elevation
of temperature of 37.°7; pure poppy oil, an elevation of 70.°5; and a
mixture of the two an elevation of temperature intermediate between
37.°7 and 70.°5.

_d._ One volume of nitric acid of sp. gr. 1.33 is agitated with 5
grammes of the oil, and notice taken of the coloration produced after
the lapse of five minutes. If the olive oil is pure, it acquires a pale
green color; in case it is mixed with sesamé or nut oil, a deep-red
color appears: poppy oil also communicates a reddish coloration, but one
less deep than the preceding.

If an acid of sp. gr. 1.22 is taken, it is still less difficult to
distinguish between sesamé, nut and poppy oils; the latter assumes, in
this case, a pale yellowish-red color.

Pea-nut oil fails to exhibit a coloration; but can be recognized by its
conversion into a white solid, when mixed with 1/5 of its volume of a
solution of caustic soda of sp. gr. 1.34.


EXAMINATION OF OLIVE OIL INTENDED FOR MANUFACTURING PURPOSES.

The chief adulterations are colza and nut oils. The latter is detected
by means of the reaction with nitric acid, as described above. Colza oil
is recognized by mixing 5 volumes of the sample to be examined, with 1
volume of sulphuric acid of sp. gr. 1.655: if colza or nut oils are
present, a brown coloration ensues; under the same circumstances, pure
olive oil assumes a pale greenish hue. In case the sample acquires a
brown color when treated with sulphuric acid, and a red coloration is
produced by the addition of nitric acid, it contains nut oil; if
sulphuric acid produces a brown coloration, and nitric acid fails to
change it, the presence of oil of colza is indicated.


EXAMINATION OF HEMPSEED OIL.

This oil is frequently adulterated with linseed oil. The reactions
exhibited by these oils are nearly identical, and the detection of the
admixture is extremely difficult. It is advisable to mix the suspected
oil with sulphuric acid, notice being taken of the elevation of
temperature produced, and to treat it with nitric acid and with dilute
potassa solution, subjecting, at the same time, an artificial mixture of
the two pure oils to the same treatment, and comparing the results
obtained.


TEA AND ITS ADULTERATION.

Among alimentary substances probably no article is subjected to more
adulteration than tea. The sophistications practised may be conveniently
divided into three classes:

1. Additions made for the purpose of giving increased bulk and weight,
which include foreign leaves and exhausted tea-leaves, and also certain
mineral substances, such as metallic iron, sand, brick-dust, etc.

2. Substances added in order to produce an artificial appearance of
strength in the tea decoction, catechu, or other bodies rich in tannin,
and iron salts being chiefly resorted to for this purpose.

3. The imparting of a bright and shining appearance to the tea by means
of various coloring mixtures or "facings," which adulteration, while
sometimes practised upon black tea, is much more common with the green
variety. This sophistication involves the use of steatite (soap-stone),
sulphate of lime, China clay, Prussian blue, indigo, turmeric, and
graphite; chromate of lead and copper salts being but very rarely
employed. The compound most frequently used consists of a mixture of
soap-stone (or gypsum) with Prussian blue, to which a little turmeric is
sometimes added.

Genuine tea is the prepared leaf of _Thea sinensis_. It contains:
moisture, 6% to 10%; theine, 0.4% to 4.0%; tannin, (green) 20%, (black)
10%; ash, 5% to 6%; soluble extractive matters, 32% to 50%; and
insoluble leaf, 47% to 54%.

  [Illustration: Fig. 16.]

  [Illustration: Fig. 17.]

  [Illustration: Fig. 18.]

  [Illustration: Fig. 19.]

The presence of foreign leaves, and, in some instances, of mineral
adulterants, in tea is best detected by means of a microscopic
examination of the suspected sample. The genuine tea-leaf is
characterized by its peculiar serrations and venations. Its border
exhibits serrations which stop a little short of the stalk, while the
venations extend from the central rib, nearly parallel to one another,
but turn just before reaching the border of the leaf (see Fig. 16). The
Chinese are said to employ ash, plum, camellia, velonia, and dog-rose
leaves for admixture with tea, and the product is stated to be often
subjected in England to the addition of the leaves of willow, sloe,
beech, hawthorn, elm, box-poplar, horse-chestnut, and fancy oak (see
Figs. 17, 18, and 19). For scenting purposes chulan flowers, rose,
jasmine, and orange leaves are frequently employed. In the microscopic
examination the sample should be moistened with hot water, spread out
upon a glass plate, and then submitted to a careful inspection, especial
attention being given to the general outline of the leaf and its
serrations and venations. Most foreign leaves will, in this way, be
identified by their botanical character. The presence of exhausted
tea-leaves may also often be detected by their soft and disintegrated
appearance. If a considerable quantity of the tea be placed in a long
glass cylinder and agitated with water, the coloring and other abnormal
bodies present frequently become detached, and either rise to the
surface of the liquid as a sort of scum or fall to the bottom as a
deposit. In this way Prussian blue, indigo, soap-stone, gypsum, sand,
and turmeric can sometimes be separated and subsequently recognized by
their characteristic microscopic appearance. The separated substances
should also be chemically tested. Prussian blue is detected by heating
with a solution of caustic soda, filtering, and acidulating the filtrate
with acid, and then adding chloride of iron, when, in its presence, a
blue color will be produced. Indigo is best discovered by its appearance
under the microscope; it is not decolorized by caustic alkali, but it
dissolves in sulphuric acid to a blue liquid. Soap-stone, gypsum, sand,
metallic iron, etc., are identified by means of the usual chemical
tests. A compound, very aptly termed "Lie-tea," is often met with. It
forms little pellets consisting of tea-dust mixed with foreign leaves,
sand, etc., and held together by means of gum or starch. This, when
treated with boiling water, falls to powder. In the presence of catechu
the tea infusion usually becomes muddy upon cooling; in case iron salts
have been employed to deepen the color of the liquor, they can be
detected by treating the ground tea-leaves with acetic acid and testing
the solution with ferrocyanide of potassium. Tea should not turn black
upon immersion in hydrosulphuric acid water, nor should it impart a blue
color to ammonia solution. The infusion should be amber-colored, and not
become reddened by the addition of an acid.


TEA ASSAY.

In the following tea assay proper the estimation of theine is not
included. The processes suggested for this determination are rather
unsatisfactory; and there appears, moreover, to exist no direct relation
between the quality of tea and the proportion of theine contained. The
tests here mentioned, in connection with those already given, will, it
is believed, usually suffice to indicate to the analyst the presence of
spent leaves, inorganic coloring matters, and other mineral
adulterations.

TANNIN.--A good process for the estimation of tannin in tea has been
published by Allen (_Chem. News_, vol. xxix. p. 169 et seq.) A standard
solution of lead acetate is prepared by dissolving 5 grammes of the salt
in distilled water and diluting the liquid to 1,000 c.c. As an
indicator, 5 milligrammes of potassic ferricyanide are dissolved in 5
c.c. of water, and an equal volume of strong ammonia-water added. The
exact strength of the lead solution is to be determined by means of a
solution of pure tannin of known strength. Two grammes of the tea to be
tested are powdered, boiled with water, and, after filtering and
thorough washing, the decoction is made up to a volume of 250 c.c.; 10
c.c. of the lead solution are now diluted with 90 c.c. of boiling water,
and the tea infusion is gradually added from a burette until a few drops
of the liquid, when filtered and added to a little of the indicator
placed upon a porcelain slab, causes a pink coloration to appear; 125,
divided by the number of c.c. of tea infusion found to be necessary to
produce the pink color, will give directly the percentage of tannin in
the sample examined. As previously stated, green tea contains 20% of
tannin, and black tea 10%. In spent tea, however, only about 2% of
tannin is present; and, although any tea deficient in this constituent
could be fortified by the addition of catechu, its determination often
affords indications of value.

THE ASH--_a. Total Ash._--5 grammes of the sample are placed in a
platinum vessel and heated over a Bunsen burner until complete
incineration has been accomplished. The vessel is allowed to cool in a
desiccator, and is then weighed as quickly as possible. In genuine tea
the total ash should not be much below 5% or much above 6%, and it
should not be magnetic; in "faced" teas the proportion of total ash is
often 10% or 15%; in "lie-tea" it may reach 30%, and in spent leaves it
may fall as low as 3%, the ash in this case being abnormally rich in
lime salts and poor in potash salts. Tea-dust sometimes contains 10% of
total ash without necessarily being considered bad in quality. In the
proposed United States tea-adulteration law (1884) a maximum of 8% of
total ash is allowed for tea-leaf.

_b. Ash insoluble in water._--The total ash obtained in _a_ is washed
into a beaker and boiled with water for a considerable time. It is then
brought upon a filter and the insoluble residue washed, dried, ignited,
and weighed. In unadulterated tea it will not exceed 3% of the sample
taken.

_c. Ash soluble in water._--This proportion is obtained by deducting ash
insoluble in water from the total ash. Genuine tea contains from 3% to
3.5% of soluble ash, or at least 50% of the total ash, whereas in spent
or exhausted tea the amount is often but 0.5%.

_d. Ash insoluble in acid._--The ash insoluble in water is boiled with
dilute hydrochloric acid and the residue separated by filtration,
washed, ignited, and weighed. In pure tea the remaining ash ranges
between 0.3% and 0.8%; in "faced" teas, or in teas adulterated by the
addition of sand, etc., it may reach the proportion of 2% to 5%.
Fragments of silica and brick-dust are occasionally to be found in the
ash insoluble in acid.

THE EXTRACT.--Two grammes of the carefully-sampled tea are boiled with
water until all soluble matter is dissolved, water being added from time
to time to prevent the solution becoming too concentrated. The solution
is poured upon a tared filter, and the remaining insoluble leaf
repeatedly washed with hot water until the filtered liquid becomes
colorless. The filtrate is now diluted to a volume of 200 c.c., and of
this 50 c.c. are taken and evaporated in a weighed dish over the
steam-bath until the weight of the extract remains constant; its weight
is then determined. Genuine tea affords from 32% to 50% of extract,
according to its age and quality; in spent tea the proportion of extract
will be greatly reduced.

INSOLUBLE LEAF.--The insoluble leaf obtained in the preceding operation,
together with the weighed filter, is placed in an air-bath and dried for
at least eight hours at a temperature of 110° C.; its weight is then
determined. In unadulterated tea the amount of insoluble leaf ranges
between 47% and 54%; in exhausted tea it may reach a proportion of 75%.

It should be noted that in the foregoing estimations the tea is taken in
its ordinary air-dried condition. If it be desired to reduce the results
obtained to a dry basis, an allowance for the moisture present in the
sample (an average of 8%), or a direct determination of the same, must
be made.

The following tabulation gives the constituents of genuine tea so far as
the ash, extract, and insoluble leaf are involved:

_Total ash_--ranges between 4.7% and 6.2%.

_Ash soluble in water_--ranges between 3% and 3.5%; should equal 50% of
total ash.

_Ash insoluble in water_--not over 2.75%.

_Ash insoluble in acid_--ranges between 0.3% and 0.8%.

_Extract_--ranges between 32% and 48%.

_Insoluble leaf_--ranges between 43% and 58%.

The table below may prove useful as indicating the requirements to be
exacted when the chemist is asked to give an opinion concerning the
presence of facing admixtures or of exhausted or foreign leaves in a
sample of tea:

_Total ash_--should not be under 4.5% or over 7%.

_Ash soluble in water_--should not be under 40% of total ash.

_Ash insoluble in water_--should not be over 3%.

_Ash insoluble in acid_--should not be over 1%.

_Extract_--should not be under 30%.

_Insoluble leaf_--should not be over 60%.

NOTE.--The British Society of Public Analysts adopt:

_Total Ash_ (dry basis)--not over 8% (at least 3% should be soluble in
water).

_Extract_ (tea as sold)--not under 30%.


MILK.

The chief constituents of milk are water, butter, caseine, lactose
(milk-sugar), traces of albumen and mineral salts. Butter is present in
the form of minute globules, held in suspension; the caseine, for the
greater part, is in solution, only a small portion being present in an
insoluble suspended condition. In milk only a few days old, the
_colostrum_ (the milk secreted during the first few days after
parturition) consists largely of rather voluminous cellular
conglomerations, containing a sufficient quantity of albumen to
coagulate upon heating.

The normal density of milk is 1.030, water being 1.000; the density
rising to 1.036, if the fluid has been skimmed.

Good milk contains, on an average, 3.7 per cent. of butter; 5.7 per
cent. of lactose, and leaves upon evaporation 12 to 14 per cent. of
solid matters.[T] The most common adulteration of milk consists in the
addition of water. This fraud is detected by means of an areometer
(_lactodensimeter_) which gives directly the specific gravity of the
fluid under examination. Should the density be much below 1.030, it is
certain that water has been added. It does not, however, necessarily
follow if it is about 1.030 that the milk is pure, since the gravity of
the fluid, which would be increased upon skimming, could be subsequently
reduced to 1.030 by the addition of water. The lactodensimeter,
therefore, although useful in the detection of a simple admixture, fails
to give reliable results if the fraud perpetrated is a double one; and a
determination of the proportion of butter present is also usually
necessary. Numerous methods have been proposed to accomplish this
estimation. The most preferable of these, owing to the rapidity with
which the operation is executed, is the use of the lactoscope
(_galactoscope_). This instrument consists of a tube provided with a
glass plate fitted at one end, and with a movable glass plate at the
other extremity. A few drops of the milk to be tested are placed between
the two plates, and the tube lengthened, by screwing out the movable
plate, until the fluid no longer transmits the light of a candle placed
at a distance of one metre. As the opacity of milk is due to the butter
present, it is evident that the proportion of this substance contained
in the sample can be estimated by the relative distance which the plates
have been separated.

  [T] The British Society of Public Analysts regard the following as the
  _minimum_ proportions of constituents in unadulterated milk:

  Fat                         2.5 per cent.
  Solids, not fat             9.   "   "
                             ----
                    Total    11.5  "   "
                    Water    88.5  "   "

  --_Trans._

The lactoscope possesses, however, but a limited degree of precision.
_M. Marchand_ substitutes to its use the following tests: A test-tube is
graduated in three equal divisions, the upper one being subdivided into
hundredths extending above, in order to determine accurately the correct
volume of the fluid, expanded, as it is, by the temperature of 40°, at
which the examination is executed. The first division of the tube is
filled with milk, a drop, or two of strong potassa lye added, and the
mixture well shaken: the second portion is then filled with ether, and
the third with alcohol. The mixture is next again thoroughly agitated,
and then exposed to a temperature of 40° in a water-bath. After standing
for several hours, a layer of fatty matter becomes sufficiently
separated to allow of measurement: but, as it contains some ether and as
a small amount of butter may still be retained in the lower aqueous
fluid, a correction of the results obtained is necessary. M. Marchand
has compiled a table, which facilitates this correction (_vide_: _Journ.
de Pharm., Novembre 1854_, and _Bulletin de l'Académie de Médecine,
Paris, 1854_, xix., p. 1101).

Previously to the introduction of Marchand's apparatus, use was made of
the _lactometer_, which consists simply of a graduated glass tube, in
which the suspected milk is allowed to remain for 24 hours, at a
temperature of 15°. After the lapse of this time, the cream present
completely separates as a supernatant layer, the thickness of which
indicates the quality of the sample taken.

_M. Lacomte_ recommends the addition of glacial acetic acid, in order to
cause the more rapid separation of the cream.

The estimation of the butter being accomplished, it is frequently
needful to determine the amount of lactose present. For this purpose,
recourse is had to Barreswil's method, based upon the reduction of
cupro-potassic tartrate by milk-sugar in the presence of alkalies. A
solution is prepared containing 40 grammes of pure crystallized sulphate
of copper, 600 or 700 grammes of caustic soda lye of sp. gr. 1.12, and
160 grammes of neutral tartrate of potassa. The sulphate of copper and
tartrate of potassa are previously dissolved separately in a little
water, the three solutions united, and water added until the fluid
acquires a volume of 1154.4 cubic centimetres. In order to standardize
this test solution, a known weight of pure lactose is dissolved in water
and the fluid added, drop by drop, from a graduated burette, to a small
flask containing 10 cubic centimetres of the copper solution, diluted
with 40 cubic centimetres of distilled water, and heated to boiling. At
first a yellow precipitate forms, which gradually turns red, and is
deposited on the bottom of the flask, leaving the solution colorless. As
soon as the test solution is completely decolorized, the addition of the
lactose solution is discontinued, and the weight of lactose
corresponding to 10 cubic centimetres of the test fluid calculated from
the quantity used. The standard of the test solution having been
determined, the above operation is repeated, the milk under examination
being substituted for the solution of pure lactose. The quantity of milk
necessary to decolorize 10 cubic centimetres of the copper solution will
evidently contain the same amount of lactose as the quantity of solution
used in the preliminary test, and the actual amount of lactose present
is very easily calculated. When an estimation of the solid matter
contained in the milk is required, a known weight is evaporated to
dryness over a water-bath, and the residue weighed. In performing this
evaporation, the addition of a known amount of sand, or ground glass, is
advisable. The amount of ash present is determined by incinerating the
residue left by the evaporation.

Foreign substances are sometimes added to milk, for the purpose of
disguising the presence of an abnormal quantity of water, the principal
of which are: chalk, bicarbonate of soda, emulsion of almonds, gum
tragacanth, gum arabic, starch, flour, decoction of barley or rice,
sugar, and cerebral substances. These bodies are detected as follows:

_Chalk._--If chalk is contained in the milk, it readily subsides upon
allowing the sample to remain at rest for some time in a flask, forming
a deposit which effervesces when heated with hydrochloric acid, and
dissolves to a solution, in which the characteristic properties of a
lime salt can be recognized.

_Bicarbonate of soda._--In presence of this compound the milk possesses
a strongly alkaline reaction, furnishes a serum having a sharp and
bitter taste, and leaves a residue of the salt upon evaporation.

_Emulsion of almonds._--The milk has a specific gravity of at least,
1.033. If it is passed through a gauze, small opaque lumps are
separated. When examined under the microscope, numerous minute globules,
having a diameter of 1/400 of a millimetre, are observed, and, upon
adding a few centigrammes of amygdaline to one or two grammes of the
milk, the characteristic odor of bitter almonds is produced.

_Gum tragacanth._--When shaken in a glass flask and allowed to rest, the
milk deposits on the sides small transparent lumps, which usually
present a slightly elongated or angular form.

_Gum arabic._--The addition of alcohol produces an abundant white opaque
precipitate.

_Starch, flour, decoction of barley, rice, etc._--Upon boiling the
suspected milk, and adding tincture of iodine, the amylaceous substances
present produce a blue coloration in the fluid.

_Sugar._--If yeast is added, and the mixture allowed to stand for some
time at a temperature of 30°, alcoholic fermentation ensues; under these
circumstances, lactose does not undergo fermentation.

_Cerebral substances._--Adulteration by these substances is probably of
much less frequent occurrence than was formerly supposed. The admixture
is detected by evaporating the milk to dryness, dissolving the residue
in ether, evaporating the etherial solution, and fusing the second
residue, which consists of fatty matters, with nitrate of potassa in a
platinum crucible. The mass is then taken up with water, and chloride of
barium added to the solution. If cerebral substances were contained in
the milk, ether will dissolve the fatty matters present, the phosphorus
of which is converted into a soluble phosphate by the calcination with
nitrate of potassa and is thrown down as a white precipitate, upon the
addition of a solution of chloride of barium. This test may be confirmed
by a microscopic examination of the milk, when the peculiar appearance
of cerebral matter will be detected.[U]

  [U] Fragments of nerves, and other organic structures, are frequently
  observed in this examination.--_Trans._


WINE.

The most common adulteration to which wines are subjected is the
addition of water: wines having a rich color are frequently mixed by the
dealer with lighter wines, and the fraud consummated by adding water.
The detection of this adulteration is somewhat difficult, as water is a
normal constituent of wine. In Paris the following method is usually
employed: As soon as the wine is confiscated, it is ascertained what
kinds of wine are manufactured by the inculpated dealer, and a statement
obtained from him, giving the proportions of alcohol, etc., contained in
the various brands. A wine is then prepared, according to the
information received, an estimation of the alcohol contained in the
prepared sample made, and the results compared with those furnished by a
similar examination of the suspected wine. In case the proportion of
alcohol is less in the suspected wine than in the prepared sample, it is
evident that a fraudulent adulteration has been committed. If, however,
the quantity of alcohol is the same in both wines, it does not
necessarily follow that the wine has escaped admixture, since this body
may have been added after the adulteration with water. In addition to
the estimation of alcohol, it is also necessary to determine the amount
of cream of tartar (bitartrate of potassa) present, as the proportion of
this salt would be sensibly decreased by the addition of alcohol and
water to the wine. This fraud could, however, be disguised by
subsequently adding the proper amount of cream of tartar.

It is also well to ascertain if two equal quantities of the prepared
sample and the wine under examination require the same amount of
solution of hypochlorite of lime for decolorization. In case the
suspected wine has been adulterated, the quantity of hypochlorite
solution used will be less than the amount necessary to decolorize the
prepared wine. Foreign coloring matter may be added by the adulterator,
but this fraud is easily detected by adding potassa to the sample: if
its coloration is natural, a green tint is produced; whereas, if foreign
matter has been introduced, the wine assumes various other colors upon
the addition of the alkali.[V]

  [V] _Cotlini_ (_Ann. du genie civil_, No. 3, 1873) states that the
  following reactions occur when artificially colored wines are heated
  with potassa:

  Pure wine                    no precipitate   greenish hue
  Elderberry     violet              "
  Beet-sugar     red                 "
  Logwood red    violet-red          "
  Privet         violet-blue         "
  Turmeric       light-blue          "

  According to _M. de Cherville_ (_Quar. Jour. Sc._), a bright violet
  coloration is produced in the above test, if litmus be present.

  Fuchsin is separated by treatment with subacetate of lead and
  addition of amylic alcohol (_Jour. de Ph. et de Ch. Mar.
  1873_).--_Trans._

The indications furnished by the above test are rendered valueless, if
the wine has been artificially colored by the addition of the coloring
matter of grape-skins; but the execution of this fraud would require
some knowledge of chemistry, and fortunately adulterators, as a class,
are deficient in this branch of science.

Another method for detecting the addition of water is based upon the
fact that fermented liquors do not contain air in solution, but only
carbonic acid; whereas, water dissolves oxygen and nitrogen. It is
executed as follows:

The wine to be tested is placed in a flask, the delivery-tube of which
is also filled, and heated; the evolved gas being collected in a tube
filled with mercury. In case the wine is pure, the disengaged gas will
be completely absorbed by potassa; if, on the other hand, water has been
added, an unabsorbed residue, consisting of oxygen and nitrogen, will
remain.

This test is useless in case water, through which a current of carbonic
acid gas has been passed for a considerable time, has been employed.
Under these circumstances, however, the presence of the gas would
probably be detected by the taste of the wine, as well as by the
estimation just mentioned, since the sample would invariably contain a
larger proportion of the gas than the standard with which it is
compared; indeed, it would be almost impossible to prepare a solution
which contained exactly the proportion of carbonic acid ordinarily
present in wine.

It remains to mention the methods employed in determining the amount of
alcohol and cream of tartar contained in wine.

The alcometrical method usually employed is based upon the difference in
density possessed by pure alcohol and by mixtures of alcohol and water.
_Gay-Lussac_ has proposed an areometer (_alcoholmeter_), provided with a
scale which directly indicates the proportion of alcohol contained in a
mixture. As the indications furnished by this instrument vary with the
temperature, and the scale is constructed on the basis of a temperature
of 15°, a correction of the results obtained is necessary if the
determination is made at other temperatures. Gay-Lussac has compiled a
table which indicates at once the required correction; the following
formula can also be used: _x = c ± 0.4 t_, where _x_ is the quantity of
alcohol present in the sample; _c_ the degree indicated by the
alcoholmeter, and _t_ the number of degrees differing from the
temperature of 15°: the second member of the formula is subtracted from,
or added to the first, as the temperature at which the estimation is
made is greater or less than 15°.[W]

  [W] Tralles alcoholmeter is almost exclusively employed in this
  country.--_Trans._

In case the wine to be examined contains substances other than water
and alcohol, which would affect its density, it is necessary, before
making use of the alcoholmeter, to distil the sample and subsequently
examine the distillate, which will consist of a simple mixture of water
and alcohol. Usually the distillation is discontinued as soon as
one-third of the sample has passed over, and a quantity of distilled
water, sufficient to render the volume of the mixture equal to the
original volume of the wine, added to the distillate: the fluid
remaining in the flask will be entirely free from alcohol. The addition
of water to the distillate is not indispensable, but otherwise it is
necessary to divide the degrees indicated by the alcoholmeter by 3, in
order to reduce the result to the original volume of the wine taken.

_M. Salleron_ offers for sale a small apparatus (Fig. 20) used in
examinations of this character, consisting of a flask, closed with a
gutta-percha cork, containing a tube which connects with a worm passing
through a cooler. The flask is supported by an iron stand, and heated
with a gas or spirit lamp.

  [Illustration: Fig. 20.]

In order to estimate the cream of tartar, the wine is evaporated to the
consistency of an extract, alcohol of 82° B. added, and the residue
obtained calcined in a crucible. The amount of salt present in the fused
mass is then determined by the alkalimetric method, as directed in all
works on quantitative analysis. The carbonate obtained from 1 gr. of
cream of tartar exactly saturates 9.75 cubic centimetres of a solution
containing 100 grammes of sulphuric acid of 66° B., and 1800 grammes of
distilled water.

The detection of toxical substances, often contained in wine, is
accomplished by the methods described under the head of detection of
poisons.


VINEGAR.

Vinegar is frequently adulterated with water, and occasionally sulphuric
acid is added to artificially increase its acidity.

The ordinary reagents--such as chloride of barium, or nitrate of
silver--are not adapted to the direct detection of sulphuric acid, or of
other mineral acids, as sulphates and chlorides, which are as readily
precipitated as the free acids, may also be present.

The following method, proposed by _M. Payen_, is usually employed:

Five centigrammes of starch (fecula) are added to a decilitre of table
vinegar, the mixture boiled for 12 or 15 minutes, and, after the fluid
has become _completely cooled_, a few drops of iodine solution added:
dilute acetic acid does not affect starch, and, in case the vinegar is
pure, a blue coloration is produced; if, on the other hand, even a
minute quantity of a mineral acid be present, the starch is converted
into dextrine, and the addition of iodine fails to cause a blue
coloration.

The water present is indirectly estimated by determining the amount of
acetic acid contained in the vinegar. This can be accomplished in
different ways: either the quantity of a standard solution of an alkali,
necessary to exactly neutralize a measured quantity of the vinegar, is
ascertained, or the vinegar is supersaturated with solution of baryta,
the excess of the salt eliminated by conducting carbonic acid through
the fluid, the precipitate removed by filtration, and the baryta salt in
the filtrate precipitated by the addition of sulphuric acid. The second
precipitate is then collected on a filter, washed, weighed, and the
amount of acetic acid present calculated: this is done by multiplying
its weight by 0.515.


SULPHATE OF QUININE.

Owing to the high price of this salt, it is frequently adulterated. The
substances used for this purpose are: crystalline sulphate of lime,
boric acid, mannite, sugar, starch, salicine, stearic acid, and the
sulphates of cinchonine and quinidine. These bodies are detected as
follows:

_a._ Upon slightly warming 2 grammes of sulphate of quinine with 120
grammes of alcohol of 21° B., the pure salt completely dissolves; if,
however, starch, magnesia, mineral salts, or various other foreign
substances are present, they are left as insoluble residues.

_b._ Those mineral substances that are soluble in alcohol are detected
by calcining the suspected sample: pure sulphate of quinine is
completely consumed; whereas, the mineral substances present remain
behind as a residue.

_c._ In presence of salicine, the salt acquires a deep red color, when
treated with concentrated sulphuric acid.

_d._ Stearic acid remains undissolved upon treating sulphate of quinine
with acidulated water.

_e._ To detect sugar and mannite, the sample is dissolved in acidulated
water, and an excess of hydrate of baryta added: a precipitate,
consisting of quinine and sulphate of baryta, is produced. Carbonic acid
is then passed through the fluid, in order to precipitate the excess of
baryta as insoluble carbonate, the fluid saturated with ammonia, to
throw down the quinine which may have been re-dissolved by the carbonic
acid, and the mixture filtered. If the salt be pure, no residue will be
obtained upon evaporating the filtrate; a residue of sugar or mannite is
formed, if these substances are present.

_f._ Sulphate of quinine invariably contains 2 or 3 per cent. of
cinchonine, originating, not from a fraudulent admixture, but from an
incomplete purification of the salt. One of the best methods for
detecting the respective quantities of quinine and cinchonine, present
in a sample of the sulphate, is the following: Several grammes of
ammonia and ether (which has previously been washed with water) are
added to one or two grammes of the salt under examination, the mixture
thoroughly agitated, and then allowed to remain at rest. The supernatant
etherial solution contains all of the quinine; the cinchonine, which is
almost completely insoluble, both in water and ether, remaining
suspended between the layers of the two fluids. The ether is next
removed by means of a stop-cock funnel, evaporated to dryness, and the
weight of the residue obtained determined. The operation is then
repeated, the ether being replaced by chloroform in which both quinine
and cinchonine are soluble. The residue, formed by the evaporation of
the second solution, will be heavier than the first residue: the
difference between the two weighings gives the weight of the cinchonine
present.

_g._ The detection of the presence of sulphate of quinidine is based
upon the difference in the solubilities of the oxalates of quinine and
quinidine. Oxalate of quinidine is sufficiently soluble in cold water
not to be precipitated by double decomposition when solutions of oxalate
of ammonia and sulphate of quinidine are mixed. Under the same
circumstances, quinine is almost completely thrown down. The test is
applied as follows:

The suspected salt is dissolved in water, a slight excess of oxalate of
ammonia added, and the precipitate formed separated by filtration. If
the salt be pure, the filtrate is scarcely rendered turbid by the
addition of ammonia; when, however, sulphate of quinidine is present, it
will be entirely contained in the filtrate, in which ammonia will
produce an abundant precipitate.


EXAMINATION OF BLOOD STAINS.

This branch of legal chemistry formerly gave but very unreliable
results. It is scarcely ten years since the reactions that are now
regarded as only secondary and confirmative in their character, and far
from conclusive, were the only ones in use: these are the tests based
upon the presence of iron and albumen in the blood. Since then, great
progress has been made in the methods employed. It must not be
understood, however, that the question under consideration always admits
of an easy and decisive solution: the stains are sometimes too greatly
altered to be identified; but in cases where the distinctive reactions
of blood can be produced, the real nature of the stains under
examination can, at present, be determined with certainty.

The tests more recently introduced consist in the production of small
characteristic crystals, termed _haemin_ crystals, and in the use of the
spectroscope. Crystals of haemin (first discovered by _Teichman_) are
formed when dry blood is dissolved in concentrated acetic acid, and the
solution evaporated to dryness: they are of a brownish-red color.
_Brücke_ first suggested an analytical method, based upon this property
of blood, which is equally characteristic and sensitive: It is only
necessary to dissolve a minute portion of the matter to be examined
(dried blood, or the residue left by the evaporation of the fluid
obtained by treating the stain, or the dried blood, with cold water) in
glacial acetic acid and evaporate the solution to dryness in order to
obtain crystals of haemin, which can be readily recognized by means of a
microscope having a magnifying power of 300 diameters. If the crystals
originate from fresh blood, they appear as represented in Fig. 21;
crystals from old blood are represented in Fig. 22.

  [Illustration: Fig. 21.]

  [Illustration: Fig. 22.]

The former possess a reddish-brown, the latter a lighter color.

The various methods now employed to produce haemin crystals were
proposed by _Hoppe-Seyler_, by _Brücke_ and by _Erdman_. Whichever
process is used, the suspected stains are at first carefully separated
from the material upon which they are deposited. If they are present on
linen, or other fabrics, the stained portions, which always remain
somewhat stiff, are cut off: they will present a reddish-brown color, in
case the cloth is not dyed: if the stains are on wood, they are removed
by means of a sharp knife; if on stone or iron, they are detached by
scraping.

In case Hoppe-Seyler's method is used, the stains, separated as
directed above, are macerated with a little _cold_ water (warm water
would coagulate the albumen present, and consequently prevent solution
taking place): the stains become soft, striae and brown or reddish
clouds are observed, especially when the dried blood is fresh, and, at
the same time, the objects upon which the stains were deposited are
decolorized. Upon allowing the fluid obtained in this way to
spontaneously evaporate on a watch-glass, a reddish brown or brownish
residue is left, from which the crystals of haemin are prepared in the
following manner: An almost imperceptible amount of common salt is added
to the residue, then, six to eight drops of concentrated acetic acid,
and the mass thoroughly mixed by stirring with a small glass rod. The
mixture is at first heated over a small gas flame, then evaporated to
dryness by the heat of a water-bath. If the stains were produced by
blood, a microscopic examination of the residue will reveal the presence
of haemin crystals. This method presents an objection: if the stained
objects have been washed with warm water previously to the examination,
the albumen will be coagulated, and the blood rendered insoluble; in
this case, cold water will fail to dissolve anything, and the residue
will not produce crystals when treated with acetic acid.

In order to remedy this difficulty Brücke operates directly upon the
stained woven or ligneous fibre, or the matter removed from the stone or
iron: The materials are boiled in a test-tube with glacial acetic acid,
the fluid decanted or filtered, a trace of common salt added, and the
liquid then evaporated on a watch-glass at a temperature between 40 and
80°. If the stains really originated from blood, haemin crystals will
now be easily perceptible upon examining the residue obtained under the
microscope.

The stained fabric, the matter removed from the stone or iron, or the
residue left by the solution with which the stains have been treated, is
placed on the glass, a trace of chloride of sodium added, and the whole
covered with a thin glass plate. A drop of acetic acid is then placed at
the edge of the plates--between which it is soon introduced by capillary
attraction--and the mixture allowed to rest in the cold for a few
moments. The mass is next brought into solution by slightly heating, and
is then evaporated by holding the plate at a considerable distance above
a gas burner. The fluid is examined from time to time under the
microscope: when it is sufficiently concentrated, crystals, presenting
the appearance represented in Figs. 21 or 22, will be observed. These
are especially well-defined, if an insoluble substance is also present
between the plates--which prevents their adhering. The fluid collects by
capillary attraction at the points of contact of the plates as a more or
less colored layer, in which the crystals are deposited.

Should the above test fail to present distinctive indications at first,
one or two fresh drops of acetic acid are introduced between the plates,
and the examination is repeated. The result is not to be regarded as
negative, until several trials have proved fruitless, as the stained
portions are but slowly soluble, and crystallization may have been
prevented by the too rapid evaporation of the acetic solution.

Haemin crystals, once seen, can hardly be confounded with other
substances; still, it is well to identify them by confirming their
insolubility in water, alcohol, and cold acetic acid, as well as their
instantaneous solubility in soda lye.

The addition of common salt is ordinarily superfluous, as it is
normally contained in the blood; but it is possible, if the stains were
washed with warm water, that, in addition to the coagulation of the
albumen, the solution of the salt may have taken place, in which case
crystals will fail to form. The addition of salt is to remedy this
possible contingency; albeit, the delicacy of the test is not affected,
even if crystals of chloride of sodium are produced, as these are easily
soluble in water, and are readily distinguished from those of haemin by
aid of the microscope.

The indications furnished by means of the spectroscope are less reliable
than those given by the production of haemin crystals; moreover, the
spectroscopic examination requires favorable weather for its execution.
Still, the test should be employed in all possible instances. The course
pursued is the following:

The aqueous fluid, with which the stains have been treated, is placed in
a watch glass, and evaporated _in vacuo_ over sulphuric acid; the last
remaining portion of the fluid being united in the bottom of the glass
by causing it to collect in a single drop. When the evaporation of fluid
is completed, the watch-glass is placed before the narrowed slit of a
spectroscope, and a ray of diffused light (or better, light reflected
from a heliostat) made to pass through the part of the glass containing
the residue. If the stains originate from blood, the absorption lines of
_haemoglobin_, consisting of two large dark bands, to the right of the
sodium line (_Frauenhofer's_ line D), will be observed in the spectrum.
In case both of the above tests fail to give positive results, it is
almost certain that the stains examined were not caused by blood. If, on
the contrary, the reactions were produced, scarcely any doubt exists as
to the presence of blood. Under these circumstances it is advisable to
confirm the results by means of the tests that have been previously
spoken of as being formerly exclusively employed; these are the
following:

_a._ 1/2 to 1 c. c. of ozonized oil of turpentine, _i. e._ turpentine
which has been exposed to the air sufficiently long to acquire the
property of decolorizing water that is slightly tinted with indigo--is
introduced in a test-tube, and an equal volume of tincture of guaiacum
added (the latter tincture is prepared by treating an inner portion of
the resin with alcohol, until its brownish color is changed to a
brownish-yellow).

If upon adding some of the substance under examination to the above
mixture a clear blue coloration ensues, and the insoluble matter thrown
down possesses a deep blue color, the presence of coloring matter of the
blood is indicated. The mixture also imparts a blue color to moistened
spots from which the blood stains have been as completely extracted as
possible. Unfortunately sulphate of iron gives the same reaction.[X]

  [X] Fresh gluten, gum arabic, and caseine also cause the blue
  coloration.--_Trans._

_b._ Upon heating the fluid obtained by treating the stains with cold
water in a test-tube, its brown or reddish color disappears, and
greyish-white flakes of coagulated albumen are thrown down. The
precipitate acquires a brick-red color, when treated with an acid
solution of nitrate of mercury containing nitrous acid. The albumen is
also coagulated by the addition of nitric acid: it assumes a more or
less yellow color, if heated with a slight excess of the acid.
Chlorine-water, especially upon heating, likewise precipitates albumen
in the form of white flakes.

_c._ If the fluid is acidulated with a few drops of acetic acid, and a
drop of ferrocyanide of potassium added, a white precipitate, or, at
least, turbidity is produced.

_d._ The flakes of albumen, separated by heating, dissolve in caustic
alkalies to a solution, from which they are re-precipitated by nitric
acid, or chlorine water.

_e._ Upon treating blood stains with chlorine-water, a solution which
contains chloride of iron, and acquires a red coloration by the addition
of sulphocyanide of potassium, is formed.

_f._ Should the stains have failed to be affected by cold water (which,
as has already been remarked, is the case when they have been previously
washed with hot water), they are treated with weak soda lye. Nitric
acid, hydrochloric acid, and chlorine water will produce in the solution
so obtained a white precipitate, which exhibits the general properties
of albumen previously described. In case the stains are deposited upon
linen, it is necessary to replace the soda by ammonia, in order to avoid
dissolving the fabric.

_g._ Solutions of the alkalies, which dissolve the albumen, leave the
coloring matters intact, and consequently do not decolorize the fabric.
If the latter is afterwards subjected to the action of hydrochloric
acid, the coloring matter is dissolved, forming a solution that leaves
upon evaporation to dryness a residue containing iron, which gives a
blue coloration with ferrocyanide of potassium, and a red coloration
with sulphocyanide of potassium.

_h._ The coloring matter of blood dissolves in boiling alcohol, to which
sulphuric acid has been added, to a brown dichroic fluid (appearing
green by transmitted light, and red by reflected light). A mixture of
rust and blood exhibits the same phenomenon.

_i._ If substances containing blood are heated in a dry tube, an odor
resembling that of burnt horn is emitted. In case the stained fabric is
a substance that would produce this odor, (such as wool, silk, or hair),
the test naturally loses all value.

_j._ If the fluid obtained by treating the stains either with water or
alkali is evaporated with a little carbonate of potassa, and the residue
heated, at first at 100°, then to redness, in a glass tube to which a
fresh quantity of carbonate of potassa has been added, cyanide of
potassium is formed. When cold, the tube is cut above the part
containing the fused mixture, the mass heated with iron-filings and
water, the fluid filtered, and the filtrate then acidulated with
hydrochloric acid: ferrocyanide of potassium will be present in the
fluid, and upon adding a drop of solution of perchloride of iron a
green, or blue, color will be produced, and a precipitate of Prussian
blue gradually thrown down.

If the stained cloth is non-nitrogenous (_per ex._: hemp, linen, or
cotton), instead of treating it with water, it may be heated until
pulverulent, mixed with carbonate of potassa, the mixture calcined, and
the operation then completed as just described. This test having given
affirmative results, the operations should be repeated with an unstained
portion of the cloth, to remove all doubt that the indications obtained
do not really originate from the fabric.

In the present state of science, it is impossible to discriminate
chemically between human and animal blood. _M. Barruel_, it is true, is
able, not only to accomplish this, but also to distinguish the blood of
the various species of animals by its odor! But this test has a somewhat
hypothetical value for scientific purposes. In regard to the crystals of
haemin, they do not present sufficient difference to allow the blood of
different animals to be distinguished. We have not yet treated of the
globules. It often occurs that these minute organs are so altered as to
be no longer recognized in the microscopic examination; when, however,
the stains are tolerably recent, they may be detected by examining the
moistened stained cloth, directly under the microscope: a discrimination
between animal and human blood is then possible: corpuscules of human
blood possess the greater size: those of the sheep, for instance, have
only one-half the diameter of the former. It is, however, but seldom
that this distinction can be made use of.[Y]

  [Y] _Menstrual blood_ is recognized by the presence of epithelial
  cells.--_Trans._


EXAMINATION OF SPERMATIC STAINS.

In cases where attempt at violence, rape or pederasty is suspected, the
expert may be required to determine the nature of stains found on
clothing, sheets, etc. The fact that the stains were produced by semen,
may often be regarded, _per se_, as criminating evidence. This class of
investigation possesses, therefore, considerable importance.

_External appearance of the stains._--Dry spermatic stains are thin, and
exhibit a greyish or, occasionally, a citron-yellow color, if present on
white cloth. In case the fabric is colored, they appear whitish and, if
on linen, present a glossy aspect. They are translucid, when observed by
transmitted light. If the fabric, upon which the stains are deposited,
is of a heavy texture, they are visible only on one side: under all
circumstances, their circumference is irregular and undulated. These
indications, however, are not conclusive, but vary according to whether
the stains were produced by the thick semen of a vigorous man, or the
aqueous seminal fluid of an aged and diseased person, or by semen more
or less mixed with the prostatic fluid. Upon moistening spermatic
stains, the distinctive stale odor of fresh semen is sometimes emitted,
but this characteristic is usually obscured by the presence of foreign
substances.

Semen stains are soluble in water, forming a gummy fluid, in which
chlorine, alcohol, bichloride of mercury, acetate and subacetate of lead
produce a white precipitate, but which fails to be coagulated by
heating. Plumbate of potassa does not impart a fawn-color to these
stains, at a temperature above 20°, as is the case with those produced
by albuminous substances.

Persulphate of iron imparts to spermatic stains a pale yellow color,

Sulphate of copper, a bluish grey color,

Cupro-potassic tartrate, a bluish grey color,

Nitrate of silver, a pale grey color,

Nitric acid, a pale yellow color.

The above reactions, separate or united, are insufficient; they are not
very delicate, and are likewise produced by stains originating from the
other varieties of mucus: the indications furnished by a microscopic
examination of the stains are alone conclusive.

_Microscopic examination._--Semen contains as its principal and
fecundating constituent, peculiar vibratory filaments, (_spermatozoa_),
held suspended in a viscous fluid. These filaments, when preserved in a
warm and moist place, retain their activity for a considerable time: it
is even possible that they may exhibit vitality in the organs, into
which they have been voluntarily or forcibly ejaculated, for ten, or
even twenty-four hours. When exposed to cold air, the spermatozoa
quickly expire; still, they preserve their form for some time, and, as
this is very characteristic, it is then easy to identify them; moreover,
since they originate exclusively in the testicles, their detection may
be considered as certain evidence of the presence of semen. In stains
produced by aged persons, and by persons enfeebled by excesses, the
spermatozoa fail to be presented; in case they are discovered, this fact
evidently does not affect the certainty of the spermatic origin of the
stains. The contrary conclusion is never absolutely certain: still, if
the use of the microscope fails to establish the presence of
spermatozoa, it is almost certain that the stains were not produced by
semen.

Of the various methods for obtaining from the stains a preparation
adapted to the microscopic examination, the one proposed by M. Charles
Robin is the most simple and reliable.

A strip, 1 c. c. in size (comprising the entire stain, if this be small,
containing its inner portion, if it be large), is cut from the fabric
under examination, care being taken that the two extremities of the
sample extend beyond the stained portion.

One end of the cloth is then immersed in a capsule, or watch-glass,
containing pure water: the stains become moistened by capillary
attraction, and, in a space of time varying from twenty minutes to two
hours, acquire the appearance of fresh semen. As soon as the stained
portion becomes swollen and softened, the surface of the cloth is gently
scraped with a spatula, and the substance removed placed on the slide of
the microscope. The particles are next slightly detached, a drop of
water added, if necessary, and the whole covered with a small plate of
very thin glass. The preparation is then examined by a microscope,
having a magnifying power of from 500 to 600 diameters. In this way, the
presence of either entire or broken spermatozoa is readily detected.
Their existence is rendered still more apparent, if the mucus present is
dissolved by adding a drop of acetic acid to the preparation.

Entire spermatozoa consist of long slender filaments, having a length
of 0.04041 to 0.04512 millimetre; the anterior extremity presents an
oval enlargement, either round or pyriform, exhibiting a double outline,
when magnified to 500 diameters. This enlarged end is termed the "head;"
the entire remaining portion being regarded as the "tail." In case the
spermatozoa are broken, they are severed either near the head or in the
middle of the tail, and a mass of detached fragments will be observed in
the microscopic examination. The spermatozoa are not the only
corpuscules revealed by the microscope; other substances, entirely
different in character, are often observed. Although the detection of
these bodies is, in itself, of no value, it will be well to enumerate
and characterize them; they are:

_a._ Oily globules.

_b._ Leucocytes, or spherical and finely granulous globules of mucus.

_c._ Corpuscules, originating from the seminal vesicles, termed
sympexions. These are rounded or ovoid, possess an irregular outline,
and are usually mixed with the spermatozoa and globules of mucus.

_d._ Crystals of phosphate of magnesia, varying greatly in size; the
largest are from 0.mm. 001 to 0.mm. 002 in length. The crystals formed
upon cooling the semen, present the form of an oblique prism, with a
rhomboidal base. Occasionally they are elongated and flattened; they
then assume the form of a rhomboid.

_e._ Epithelial cells; originating from the mucous follicles of the
urethra.

_f._ Irregular grains of dust; soluble in acetic and hydrochloric acids,
with gaseous evolution.

_g._ Brownish-red grains of rust; only slightly soluble in acetic acid,
but easily soluble in hydrochloric acid.

_h._ Filaments of the strained fabric; detected by their texture, and
general appearance.

_i._ Grains of starch, in case the cloth has been stiffened. These are
almost invariably swollen, and are frequently broken and deformed.

If the examination is to be secretly executed, and the cloth cannot
well be cut, it is rolled in a cone, in such a way that the external
side contains the stained portion. The lower extremity of the cone
(which should be free from stains) is dipped in a watch-glass containing
water, so as to avoid directly wetting the stains. The cone soon becomes
moistened by absorption, and the operation is then completed in the same
manner as when the fabric has been cut; which is always preferable, when
possible.

The examination of spermatic stains consists, then, in moistening the
stains with water, separating them as completely as possible from the
stained cloth, and determining the presence of the spermatozoa by means
of the microscope.

All other tests are valueless; even their execution for confirmatory
purposes is not advisable; inasmuch as they fail to possess a
distinctive character, and the reagents employed in their production may
destroy the fabric, and thus prevent the formation of the only
conclusive reaction--the detection of the spermatozoa.

In case the stains are deposited upon a woman's chemise, they are
usually present on both the front and back portions, and are sometimes
to be found on the sleeves. When a man's shirt is under examination,
especial attention should be given to the anterior portions. The
pantaloons are also often stained; usually in the interior, but
sometimes also on the exterior, just above the thighs. In reporting the
decision to the court, as to the nature of the stains, their precise
position should invariably be stated, as, by this means, the
circumstances attending the commission of the crime may be, at least
partially, elucidated.


  THE END.




APPENDIX.


The following list of the literature of toxicology, and its allied
branches, will, it is hoped, be of service to those readers who are
desirous of obtaining further information on the subjects treated in
this work.--_Trans._


BOOKS.

  *Accum*; A treatise on adulteration of food, and culinary poisons.
                                                           London, 1822.

  *Adrien*; Recherches sur le lait au point de vue de sa composition, de
      son analyse, de ses falsifications et surtout de
      l'approvisionnement de Paris.                         Paris, 1859.

  *Angell and Hehner*; Butter; its analysis and adulterations.
                                                           London, 1874.

  *Anglada*; Traité de toxicologie.                         Paris, 1835.

  *Atcherly*; Adulteration of food.                        London, 1874.

  *Bandein*; Die Gifte und ihre Gegengifte.                 Basel, 1869.

  *Beck*; Elements of medical jurisprudence.               Albany, 1851.

  *Bellini*; Lezionis perementali di Tossicologia.        Firenze, 1865.

  *Bergman*; Zur Kentniss der putriden Gifte.              Dorpat, 1868.

  *Bernard*; Leçons sur les substances toxiques.            Paris, 1857.

  *Billard*; Considerations medico-légale sur les empoisonnements par
      les irritants.                                        Paris, 1821.

  *Blondlot*; Sur la recherche de l'arsenic par la methode de Marsh.
                                                            Nancy, 1857.

  _Ibid_; Sur la recherche toxicologique du phosphore par la coloration
      de la flamme.                                         Nancy, 1861.

  _Ibid_; Sur le dosage de l'antimoine dans les recherches
      toxicologiques.                                       Nancy, 1865.

  *Boettcher*; Ueber Blutkrystalle.                        Dorpat, 1862.

  *Bonsels*; Ein Beitrag zur Analyse des Arsens, vorzugsweise in
      gerichtlichen Fällen.                                  Kiel, 1874.

  *Borie*; Catechisme toxicologique.                       Tuelle, 1841.

  *Bouchardt et Quevenne*; Du lait.                         Paris, 1857.

  *Bowman and Bloxam*; Medical chemistry.                 London, 1874.


  *Briand et Chaudé*; Manuel complet de médicine légale; contenant un
      manuel de chimie légale.                              Paris, 1873.

  *Buchner*; Toxikologie.                               Nüremburg, 1859.

  *Bureaux*; Histoire des falsifications des substances alimentaires.
                                                            Paris, 1855.

  *Chapman*; Manual of Toxicology.                         London, 1853.

  *Chatin*; Recherches experimentals et considerations sur quelques
      princips de la toxicologie.                           Paris, 1844.

  *Chiaje*; Tossicologia.                                  Napoli, 1835.

  *Chaussier*; Médicine légale.                             Paris, 1858.

  *Chevalier*; Dictionaire des alterations et falsifications des
      substances alimentaires, médicamenteuses et commerciales, avec
      l'indication des moyens de les reconnaitre.           Paris, 1856.

  _Ibid_; Essais practiques sur l'examen chimique des vins, considéré
      sous la rapport judiciaire.                           Paris, 1857.

  *Christison*; A treatise on poisons.                   Edinburg, 1836.

  *Collier*; Paradoxology of poisoning.                    London, 1856.

  *Cooper*; Tracts on medical jurisprudence.               Phila., 1819.

  *Cormenin*; Memoire sur l'empoisonnement par l'arsenic.   Paris, 1842.

  *Cotter*; Adulteration of liquors.                        N. Y., 1874.

  *Cottereau*; Des alterations et des falsifications du vin, et des
      moyens physiques et chimiques employés pour les reconnaitre.
                                                            Paris, 1851.

  *Cox*; Poisons; their effects, tests and antidotes.      London, 1852.

  *Culbrush*; Lectures on the adulteration of food, and culinary
      poisons.                                            Newburg, 1823.

  *Dalton*; Adulteration of food.                          London, 1857.

  *Divergie*; Médicine légale.                              Paris, 1852.

  *Dragendorff*; Beiträge zur gerichtlichen Chemie einzelner organischen
      Gifte.                                       St. Petersburg, 1872.

  _Ibid_; Untersuchungen aus dem pharmaceutischen Institut in Dorpat.
                                                   St. Petersburg, 1872.

  _Ibid_; Manuel de toxicologie; traduit par E. Ritter.     Paris, 1873.

  *Druitt*; On wines.                                      London, 1866.

  *Duflos*; Die wichtigsten Lebenbedürfnisse, ihre Aechtheit und Güte;
      Verunreinigungen, Verfälschungen, etc.              Breslau, 1846.

  _Ibid_; Die Prüfung chemischer Gifte.                   Breslau, 1871.

  _Ibid_; Handbuch der angewandten gerichtlich-chemischen Analyse der
      chemischen Gifte; ihre Erkennung in reinem Zustand und in
      Gemischen betreffend.                               Leipzig, 1873.

  *Duflos u. Hirsch*; Das Arsen; seine Erscheinung, u. s. w.
                                                          Breslau, 1842.

  *Dupasquier*; Consultation medico-légale relative à une accusation
      d'empoisonnement par le plomb. Lyon, 1843.

  *Erhard*; Die giftigen pflanzenalkaloiden und deren Ausmittelung auf
      mikroskopischem Wege.                                Passau, 1867.

  *Eulenberg*; Die Lehre von den schädlichen und giftigen Gasen.
                                                     Braunschweig, 1849.

  *Flandin*; Traité des poisons.                            Paris, 1852.

  *Flandin et Danger*; De l'arsenic.                        Paris, 1853.

  *Fop*; Adulteration of food.                             London, 1855.

  *Fraise*; Alimentation publique; le lait, ses falsifications, etc.
                                                            Nancy, 1864.

  *Frank*; Manuel de toxicologie; traduit de l'allemand par Vrankan.
                                                           Anvers, 1803.

  *Fresenius*; Auffindung unorganischen Gifte in Speisen, u. s. w.
                                                     Braunschweig, 1856.

  *Friedrich*; Die Verfälschung der Speisen und Getränke. Münster, 1859.

  *Galtier*; Traité de toxicologie.                         Paris, 1855.

  *Galtier de Claubry*; De la recherche des alcalis organiques dans les
      cas d'empoisonnement.                                 Paris, 1862.

  *Ganeau*; Alterations et falsifications des farines.      Lille, 1856.

  *Garnier*; Des falsification des substances alimentaires et des moyens
      de les reconnaitre.                                   Paris, 1844.

  *Gerhardt*; Précis d'analyse pour la recherche des alterations et
      falsifications des produits chimiques et pharmaceutiques.
                                                            Paris, 1860.

  *Garland*; Précis d'analyse chemique qualitative.         Paris, 1855.

  *Gmelin*; Allgemeine Geschichte der thierischen und mineralischen
      Gifte.                                               Erfurt, 1806.

  *Gorup-Besanez*; Anleitung zur qualitativen und quantitativen
      zoochemischen Analyse.                         Braunschweig, 1871.

  *Gosse*; Des taches, au point de vue medico-légale.       Paris, 1862.

  *Griffin*; The chemical testing of wines and spirits.    London, 1872.

  *Griffith and Taylor*; A practical manual of the general, chemical,
      and microscopical character of the blood, etc.       London, 1843.

  *Guerin*; Nouvelle toxicologie.                           Paris, 1826.

  *Guy*; Principles of forensic medicine.                  London, 1843.

  *Gwosden*; Ueber die Darstellung des Hämin aus dem Blut und den
      qualitativen Nachweis minimaler Blutmengen.            Wien, 1866.

  *Hager*; Untersuchungen.                                Leipzig, 1873.

  *Hartung-Schwarzkoff*; Chemie der organischen Alkalien. München, 1855.

  *Hassall*; Adulteration of food.                         London, 1855.

  *Van Hassett*; Handbuch der Giftlehre.             Braunschweig, 1862.

  *Helwig*; Das mikroskop in der Toxikologie.               Mainz, 1864.

  *Herman*; Lehrbuch der experimentellen Toxikologie.      Berlin, 1875.

  *Hitzig*; Studien über Bleivergiftung.                   Berlin, 1870.

  *Hoffman*; Manual of chemical analysis.                   N. Y., 1873.

  *Hoppe-Seyler*; Handbuch der physiologisch und pathologisch chemischen
      Analyse.                                             Berlin, 1870.

  _Ibid_; Medicinisch-chemische Untersuchungen.            Berlin, 1871.

  *Horsley*; The toxicologist's Guide.                     London, 1866.

  *How*; Adulteration of food and drink.                   London, 1855.

  *Huseman*; Handbuch der Toxikologie.                     Berlin, 1870.

  *Jaillard*; De la toxicologie du bichromate de potasse.
                                                       Strasbourg, 1861.

  *Jones (H. Bence)*; Chemistry of wines.                  London, 1874.

  *Klincke*; Die Verfälschung der Nahrungsmittel, Getränke, etc.
                                                          Leipzig, 1858.

  *v. Kupffer*; Handbuch der Alkoholometrie.                 Wien, 1866.

  *de Lapparent*; Les moyens de constater la pureté des principales
      huiles fixes.                                     Cherbourg, 1855.

  *Lefort*; Etudes chimiques et toxicologiques sur la morphine.
                                                            Paris, 1861.

  *Legrand*; Traité de médicine légale et de jurisprudence médical.
                                                            Paris, 1873.

  *Letheby*; On food.                                       N. Y., 1872.

  *Lerwin*; Toxikologischen Tabellen.                      Berlin, 1856.

  *Liebreich*; Outlines of Toxicology.                     London, 1875.

  *Lindes*; Beiträge zur gerichtlichen Chemie.             Berlin, 1852.

  *Lunel*; Guide pratique pour reconnaïtre les falsifications et
      alterations des substances alimentaires.              Paris, 1874.

  *Malle*; Essai d'analyse toxique génerale. Strasbourg, 1838.

  *Marset*; Composition, adulteration, and analysis of food.
                                                           London, 1856.

  *Marshall*; Remarks on arsenic.                          London, 1817.

  *Marx*; Geschichtlich Darstellung der Giftlehre.      Göttingen, 1829.

  *Mata*; Tratado de medicina y cirugia legal.              Paris, 1874.

  *Mayercon and Bergeret*; Recherches sur la passage de l'arsenic et de
      l'antimoine dans les tissus et les humeurs.           Paris, 1874.

  *Meissner*; Aräometrie in ihrer Anwendung auf Chemie und Technik.
                                                             Wien, 1816.

  *Mitchell*; Falsification of food.                       London, 1848.

  *Mohr*; Chemische Toxikologie.                     Braunschweig, 1874.

  *Monier*; Memoires sur l'analyse de la lait et des farines.
                                                            Paris, 1858.

  *Montgarney*; Essai de toxicologie.                       Paris, 1818.

  *Muller*; Anleitung zur Prüfung der Kuhmilch.              Bern, 1858.

  *Münk und Leyden*; Phosphorvergiftung.                   Berlin, 1865.

  *Neubauer*; Chemie des Weines.                        Wiesbaden, 1874.

  *Neuman*; Die Erkennung des Bluts bei gerichtlichen Untersuchungen.
                                                          Leipzig, 1869.

  *Normandy*; The commercial hand-book of chemical analysis.
                                                           London, 1875.

  *Odling*; A course of practical chemistry.               London, 1872.

  *Oesterlen*; Das menschliche Haar und seine gerichtärtliche Bedeutung.
                                                         Tübingen, 1875.

  *Orfila*; Rapport sur les moyens de constater la presence de l'arsenic
      dans les empoisonnements par ce toxique.              Paris, 1841.

  _Ibid_; Traité de médicine légale.                        Paris, 1848.

  _Ibid_; Elements de chimie médicale.                      Paris, 1851.

  _Ibid_; Traité de toxicologie.                            Paris, 1852.

  *Otto*; Anleitung zur Ausmittelung der Gifte, und zur Erkennung der
      Blutflecken bei gerichtlich-chemischen Untersuchungen.
                                                     Braunschweig, 1870.

  *Payen*; Substances alimentaires.                         Paris, 1856.

  *Pelliken*; Beiträge zur gerichtlichen Medizin, Toxikologie und
      Pharmakodynamik.                                  Würztburg, 1858.

  *Petit Lafitte*; Instruction simplifiée pour la constatation des
      propriétées des altérations et des falsifications des principales,
      denrées alimentaires.                              Bordeaux, 1858.

  *Plaff*; Anleitung zur vornahme gericthlicher Blutuntersuchungen.
                                                           Plauen, 1860.

  *Pierce*; Examination of drugs, chemicals, etc.       Cambridge, 1852.

  *Planta*; Verhaltung der wichtigsten Alkaloiden gegen Reagenten.
                                                       Heidelberg, 1846.

  *Pleck*; Toxicologia.                                   Viennae, 1801.

  *Prescott*; Chemical examination of alcoholic liquors.    N. Y., 1875.

  *Preyer*; Die Blutkrystalle.                               Jena, 1871.

  *Reese*; A manuel of Toxicology.                         Phila., 1874.

  *Reveil*; Introduction à un cours de toxicologie.         Paris, 1859.

  *Reyer*; Die Blausäure physiologisch untersucht.          Bonn., 1868.

  *Rich*; The analyst's annual note-book for 1874.         London, 1875.

  *Ritter*; Ueber die Ermittelung von Blut, Samen und Excrementenflecken
      in Kriminalfällen.                                Würztburg, 1854.

  _Ibid_; Beiträge zur gerichtlichen Chemie.       St. Petersburg, 1872.

  _Ibid_; Manuel de chimie practique, analytique, toxicologique et
      zoochimique.                                          Paris, 1874.

  *Robinet (fils)*; Manuel practique d'analyse chimique des vins.
                                                            Paris, 1872.

  *Rebuteau*; Elements de Toxicologie et de médecine légale appliquée à
      l'empoisonnements. Paris. 1873.

  *Roucher*; Recherches toxicologiques.                     Paris, 1852.

  *Roussin*; Falsification des vins par l'alun.             Paris, 1861.

  *Ryan*; Medical Jurisprudence.                           London, 1836.

  *Schmidt*; Ein Beitrag zur Kentniss der milch.            Dorpat 1874.

  *Schmidt*; Diagnostik verdächtlicher Flecken.           Leipzig, 1848.

  *Schneider*; Die gerichtliche Chemie.                      Wien, 1852.

  *Schroff*; Toxikologische Versuche über Arsen.             Wien, 1858.

  _Ibid_; Beiträge zur Kentniss des Aconite.

  *Simon*; Die Frauenmilch.                                Berlin, 1838.

  *Sonnenkalb*; L'Aniline et ses couleurs, au point de vue
      toxicologique.                                      Leipzig, 1864.

  *Sonnenschein*; Ueber ein neues Reagent auf Alkaloiden.  Berlin, 1857.

  _Ibid_; Handbuch der gerichtliche Chemie.                Berlin, 1869.

  *Soubeiran*; Nouveau Dictionnaire des falsifications et des
      alterations des aliments, etc.                        Paris, 1874.

  *Speyer*; Recherche de la colchicine.                    Dorpat, 1870.

  *Spratt*; Toxicology.                                    London, 1843.

  *Stowe*; A toxicological chart.                          London, 1872.

  *Tanner*; Memoranda on Poisons.                          London, 1872.

  *Tardieu*; Etude medico-légale sur l'empoisonnement.      Paris, 1866.

  *Tardieu, Lorain et Roussin*; Empoisonnement par la strychnine,
      l'arsenic, et les sels de cuivre.                     Paris, 1865.

  *Tatra*; Traité d'empoisonnement par l'acide nitrique.    Paris, 1802.

  *Taylor*; Poisoning by strychnine.                       London, 1856.

  _Ibid_; On poisons, in relation to medical jurisprudence and medicine.
                                                           London, 1859.

  _Ibid_; A manual of medical jurisprudence.               Phila., 1873.

  _Ibid_; The principles and practice of medical jurisprudence.
                                                           Phila., 1873.

  *Thompson*; Medical jurisprudence.                       London, 1831.

  *Traill*; Medical jurisprudence.                         Phila., 1841.

  *Trommer*; Die Kuhmilch in Berzug auf ihre Verdünnung und
      Verfälschung.                                        Berlin, 1859.

  *Valser*; Etude sur la recherche, les caractères distinctifs, et la
      dosage des alcaloïdes organiques naturels.            Paris, 1862.

  *Vernois*; Du lait chez la femme dans l'etât de santé et dans l'etât
      de maladie.                                           Paris, 1858.

  *Vogel*; Eine neue Milchprobe.                        Stuttgart, 1860.

  *Walchner*; Die Nahrungsmittel des menchens, ihre Verfälschungen und
      Verunreinigungen.                                    Berlin, 1875.

  *Walther*; Ueber Erkennung des Arsens bei Arsenvergiftung.
                                                         Bayreuth, 1854.

  *Wanklyn*; Milk Analysis.                                London, 1874.

  *Wenke*; Das Bier und seine Verfälschung.                Weimar, 1861.

  *Werber*; Lehrbuch der praktischen Toxikologie.        Erlangen, 1870.

  *Wharton and Stille*; Medical Jurisprudence.             Phila., 1855.

  *Wickler*; Toxikologische Briefe.                        Weimar, 1852.

  *Wirthgen*; Die verschiedenen Methoden zur ermittelung von Blutflecken
      in forensischen Fallen.                            Erlangen, 1861.

  *Witting*; Uebersicht der wichtigsten Erfahrungen in der Toxikologie.
                                                         Hannover, 1827.

  *Wöhler und Liebold*; Das forensisch-gerichtlichen Verfahren bei einer
      Arsenvergiftung.                                     Berlin, 1847.

  *Wood*; Therapeutics, materia medica and Toxicology.     Phila., 1874.

  *Wormely*; The micro-chemistry of Poisons.                N. Y., 1867.

  *Wurtz*; Chimie médicale.                                 Paris, 1868.

  *Zalewsky*; Untersuchung über das Conin.                 Dorpat, 1869.


MEMOIRS.


On poisons generally and those not elsewhere classified.

  *Accum*; Ed. month. Rev. iii, 276; Quar. Rev. xxiv, 341; Ed. Rev.
      xviii, 370.

  *Andrews*; Sill Am. Jour. [2] xlvii, 25.

  *Bouis*; Compt. rend. lxxiii.

  *Bunsen*; Ann. Ch. Pharm. cvi, 1.

  *Brunner*; Archiv. der Pharm. ccii, 4.

  *Cossa*; Gaz. Med. di Lomb., 1863.

  *Diakanow*; Med. Chem. Unters. ii, 144.

  *Duflos u. Millon*; Ann. Chem. Pharm. xlix, 308.

  *Elliot and Storer*; Am. Jour. Pharm., Sept., 1860

  *Joubert*; Compt. Rend., No. 26.

  *Moitessier*; Annal d'Hygiene, 1868.

  *Orfila*; Mem. de l'acad. roy. de méd. viii. 493.

  *Otto*; Ann. chem. Pharm. c., 39.

  *Pellissie*; Jour. de Pharm. et de chim., Jan., 1874.

  *Reveil*; Compt. Rend. lx, 433.

  *Reynolds*; The Irish Hosp. Gaz. Feb. 15, 1873.

  *Selmi*; Gaz. Chim. Ital. 1874. fasc. I, ii.

  *Stein*; Polyt. Centralb., 1866, p. 1023 and 1870, pp. 1035, 1209.

  *Vierchow*; Arch. f. path. anat. xxi, 444.


On the destruction of organic matter.

  *Brande*; Arch. f. Pharm. xlviii, 206.

  *Buchner*; N. rept. f. Pharm. xvii, 21.

  *Fresenius*; Zeitsch. f. anal. Chem. 1 Jahrg, 447.

  *Fype*; Jour. f. prakt. Chem. lv, 103.

  *Graham*; Phil. Mag. [4] xxiii.

  *Liebig*; Chem. Centbl., 1857, v. 357.

  *Ludwig*; Arch. f. Pharm. xcvii, p. 23.

  *Schacht*; Arch. f. Pharm. lxxvi, 139.

  *Schneider*; Jahrb. der Chem. 1851, 630.

  *Sonnenschein*; Deutsche Klinik, 1867, No. 3.

  *Wurtz*; Am. Jour. Sci. [2] xi, 405.


On the detection of Arsenic.

  *Avery*; Sill Am. J. [2] xlvii, 25.

  *Barker*; Am. Chem. June, 1872.

  *Becker*; Arch. f. Pharm. xlvi, 287.

  *Bettendorff*; Zeitsch. f. Chem. v. 492, 592.

  *Blondlot*; Jahresb. 1863, 681; Compt. Rend. July 7, 1845.

  *Bloxam*; Jahresb. f. Chem. 1860. 645; Chem. Soc. Q. Jour. xiii, 14,
      138.

  *Brescius*; Ding. poly. Jour., clxxxvi, 226.

  *Buchner*; Rept. f. Pharm. xii.

  *Christison*; Lond. and Edinb., Jour. Med. Sc., Sept., 1843; Med.
      Recorder, Apr., 1827.

  *Davy*; Jahresb., 1858, 609.

  *Draper*; Dingl. poly. Jour. cciv. 385.

  *Elliot and Storer*; Sill. Jour. 32, p. 380.

  *Erlenmeyer*; Zeitsch. f. Ch. u. Pharm. 1862, 38.

  *Feuchtwanger*; Sill. Jour. xix, 339.

  *Franck*; Zeit. f. anal. Chem. iv. 201.

  *Fresenius*; Arch. f. Pharm. lxii, 57; Ann. der Chem. u. Pharm. xliii.
      361; ibid, xlix, 275; Zeits. f. anal. Chem. vi, 196; ibid ii, 19;
      ibid i. 483; Qual. Chem. Anal. p. 346.

  *Fresenius u. v. Baho*; Pogg, Anal. vol. xc, 565; Ann. Chem. Pharm.
      xlix, 287.

  *Fype*; Phil. mag. ii 487; Jour. f. prakt. Chem. lx. 103.

  *Gatehouse*; Chem. News. No. 699, 1873.

  *Gaultier de Claubry*; J. Pharm. [3] xxii, 125.

  *Graham*; Ann. Chem. Pharm. cxxi, 63: Elements of Chem. 2nd. edit.
      vol. ii, 215.

  *Gray*; Chem. News, v. 23 p. 73.

  *Hager*; Pharm. Zeitsch. 1870, No. 27: Ding. poly. Jour. vol. 207, No.
      6; Centralhalle xiii, 195.

  *Hasson*; Compt. Rend, lxvii, 56.

  *Houzeau*; Ding. poly. Jour. Bd. 207, Heft. 2, 3.

  *Hume*; Phil. Mag. Sept. 1812, 109.

  *Keber*; Viertlj. f. gerichtl. Med. ix. 96.

  *Kirschgassner*; J. f. prakt. Chem. lxviii. 168; Jahresb., 1860, 170.

  *Lippirt*; J. f. prakt. Chem. lxviii, 168; Jahresb., 1860, 170.

  *Lois*; Oest. Zeitsch. f. prakt. Heilkunde, xlix, 1859.

  *Mayer*; Pharm. Zeitsch. Russ. 2 Jahrgang.

  *Meyer*; Ann. Chem. u. Pharm., lxvi.

  *Montmeja*; La France Méd., Jan. 8, 1873.

  *Odling*; Guys. Hosp. Rep. [3] v. 367; Zeitsch. f. anal. Chem. ii.
      388.

  *Pearson*; Sill, Am. J. [2] xlviii, 190.

  *Puller*; Zeitsch. f. anal. Chem. x, 52.

  *Rose*; Pogg. Annal., vol. xc; Zeitsch. f. anal. Chem. i, 418; Chimie
      Anal. Paris, 1859, p. 405.

  *Roussin*; Jahresb. 1866, 801.

  *Saikowski*; Arch. f. path. Anat. xxxi, 400.

  *Selmi*; Dent. Chem. Gess. Ber. 1872, 477.

  *Schafer*; Jour. f. prakt. Chem. lxxxii, 286.

  *Schneider*; Wien. Akad. Ber. 1851, vi, 409

  *Sklarek*; Arch. f. Anat. u. Phys. 1866, 481.

  *Slater*; Chem. Gaz. 1851, 57.

  *Sonnenschein*; Arch. f. Pharm, cxciii, 245: ibid. [2] cxliii, 250.

  *Taylor*; Guys. Hosp. Rep. ii, 83; ibid. vi; Pharm. Zeitsch. f. Russl.
      10, Jahrg. 129.

  *Ugers*; Ann. Chem. Pharm. clix, 127.

  *Ures*; Dict. Arts, etc., new edit, i, 189.

  *Vitry*; Annal d'hygiène publ. xxxvi, 14.

  *Wackenroder*; Arch. f. Pharm. lxx, 14.

  *Watt's* Chem. Dict. i, 365; Supp. 215.

  *Werther*; J. pr. Chem. lxxxii, 235; Jahresb. 1861, 851.

  *Wiggers*; Canstatt's Jahresb. der Pharm. 1864.

  *Wittstein*; Zeitsch. f. anal. Chem. ii, 19.

  *Wohler*; Ann. der Chem. u. Pharm. lxix, 364; Mineral Analyse,
      Göttingen, 1861, 213.

  *Wood and Doremus*; N. Y. Med. Press, 1859, 543.

  *Zenger*; Zeitsch. f. Ch. Pharm. 1862, 38; Jahresb. 1862, 595.


On the detection of Antimony.

  *Bellini*; Jhb. f. Pharm. 1868, p. 453.

  *Bottger*; Chem. Centralbl., 3 Jahrgang.

  *Bunsen*; Ann. Chem. Pharm. cvi, p. 3.

  *Hofman*; Ann. Chem. Pharm. p, 155; Chem. Soc. Quar. J. xiii, 79.

  *Millon and Levaran*; Compt. Rend. 21.

  *Odling*; Guys Hosp. Rep. [3] ii, 249.

  *Pfaff*; Pogg. Ann. f. Phys xl, 339.

  *Thompson*; Jour. f. prakt. Chem. ii, 369.

  *Vogel*; ibid, xiii, 57.


On the detection of Mercury.

  *Buchner*; N. rept. f. Pharm. xvii, 272.

  *Erdman and Marchand*; Jour. f. prakt. Chem. xxxi.

  *Hittdorf*; Pogg. Annal. cvi.

  *Konig*; Jour. f. prakt. Chem. lxx.

  *Mayencon and Bergeret*; Jour. de l'Anat. et de la Physiol. 1873, No.
      1; Jour. de Pharm. et de Chim., Aug., 1873.

  *Schneider*; Ber. d. Wien, Akad. d. Wiss. xl.

  *Wormley*; Chem. News, ii, No. 43.


On the detection of Phosphorus.

  *Barrett*; Phil. Mag. [4] xxx, 321.

  *Blondlot*; Jour. de. Phy. et de Chim. 3 é serie xl, p. 25.

  *Bostelaer*; Jour. de Pharm. et de Chim., May, 1873.

  *Christoffle and Beilstein*; Ann. de Chim. v, iii, p. 80.

  *Dalmon*; Zeitsch. f. anal. Chem. 1871, 132.

  *Dusard*; Zeitsch. f. anal. Chem. i, 129; Compt. rend. xliii, 1126.

  *Ferrand*; La France med., Jan. 18, 1873.

  *Fresenius and Neubauer*; Zeitsch. f. Anal. Chem. i, 366.

  *Hager*; Zeitsch f. anal. Chem. 1870, 465.

  *Hoffman*; Jahresb. 1859, 663.

  *Klewer*; Pharm. Zeitsch. f. Russl., 386.

  *Kohler*; Poly. centralh., 1871, 263.

  *Lapeyrere*; La France méd., Jan. 4, 1873.

  *Lefort*; Jour. de Pharm. et de Chim., Aug., 1874.

  *Lispowitz*; Ann. f. Phys. u. Pharm. cviii, 625.

  *Mistcherlich*; Jour. f. prakt. Chem. lxvi, 238.

  *Mulder*; Arch. f. d. holl. Zeit. ii, 4; Zeitsch. f. Anal. Chem. ii,
      3.

  *Otto*; Zeitsch. f. Chem. [2] ii, 733.

  *Pribram*; Zeitsch. f. anal. Chem. 1871, 109.

  *Ritter*; Thése de doctorat es sciences, Paris, 1872.

  *Scherer*; Ann. Ch. Pharm. cxii, 214.

  *Schieffendecker*; Zeitsch. f. anal. Chem. 1872, iii.

  *Schom*; Zeitsch. f. anal. Chem. [2] v, 664.

  *Wiggers*; Canstatt's Jahresb. f. Pharm. 1854.


On the detection of Prussic Acid.

  *Almen*; Chem. Centralb., 1871, 797.

  *Bonjean*; Compt. rend. lxx, 532.

  *Braun*; Zeitsch. f. anal. Chem. iii, 464.

  *Duvignan and Parent*; Am. Med. Rec. 1819, 534.

  *Hagenbach*; Arch. f. path. Anat. xl, 125.

  *Hoppe-Seyler*; Vierschow's Arch. f. path. Anat 38.

  *Jacquemin*; Compt. rend. lxxxix, 1499, 1502.

  *Letheby*; Lond. Lanc. 1844, 244; ibid, vol. 2, p. 139.

  *Ralph*; N. Jahresb. f. Pharm. xxx, 179.

  *Rennard*; Pharm. Zeitsch. f. Russl. xii, No. 8.

  *Schonbein*; Zeitsch. f. anal. Chem. 1868, 503.

  *Siegel*; Arch. f. Heilkunde, 1858.

  *Struve*; Zeitsch. f. anal. Chem. 1873, i; Mon. Scien. Ques. Juin,
      1874, 538.

  *Taylor*; Ann. Ch. Pharm. lxv, 263.


On the detection of Alkaloids in general.

  *Anderson*; Pharm. Centralbl., 1848, 591.

  *Armstrong*; J. Chem. Soc., v. 8, p. 56.

  *Back*; Jour. f. prakt. Chem. Nos. 5-6, 1873.

  *Beas*; Jour. de Phys. et de Chim., Sept. 1872.

  *Bolton*; (trans. of the Stas-Otto method) Am. Chem., Nov., 1873.

  *Bonnemains*; Compt. Rend. xxxvi, 150.

  *Bouchardt*; Ann. de Phys. et de Chim., 3e série. t. ix.

  *Brunner*; Archiv der Pharm., April, 1873.

  *Buignet*; Jour. de Pharm. et de Chim. t. xx, 252.

  *Deane and Brady*; Chem. Soc. J. [2] iii, 34.

  *Deefs*; N. Jahresb. f. Pharm. ii, 31; Wittstein's Viertelj. vi.

  *Dragendorff*; Pharm. Zeitsch. f. Russl. ii, 459; Archiv der Pharm.
      May, 1874.

  *Erhard*; N. Jahresb. f. Pharm. xxv, 129, 193, 283; ibid, xxvi, 9,
      129.

  *Ewers*; Pharm. Zeitsch. f. Russl. xii, No. 23.

  *Graham and Hofman*; Chem. Soc. Qu. J. v, 173; Pharm. J. Trans. xi,
      504; Ann. Ch. Pharm. lxxxiii, 39.

  *Grandean*; Bull. Soc. Chim. [2] ii, 74.

  *Guy*; Pharm. Jour. ii, pp. 553, 602; ibid, iii, pp. 11, 112.

  *Hagers*; Chem. Ctbl., 1869, 131.

  *Horsley*; Chem. News, v, 355

  *Huseman*; Ann. Chem. Pharm. cxxviii, 305.

  *Kletzinsky*; Mitthel. v. d. Geb. d. rein. u. angew. Chem. 1865.

  *Kohler*; Archiv der Pharm. Mar. 1873.

  *Kuhne*; Ann. Chem. Pharm. vol. civ.

  *Lefort*; Zeitsch. f. anal. Chem. i, 134.

  *Lehrman*; Archiv der Pharm. 2 Bd. lxxvi, 144.

  *Liebig*, Poggendorff u. Wohler; Handwörterb. d. Chem. 2 Aus. i, 464.

  *Macadams*; Pharm. Jour. Trans. xvi, 120, 160.

  *Marchattie*; Chem. News. x, 183.

  *Marme*; Bull. Soc. Chim [2] ix, 203; Zeitsch. f. rat. Med. 1867.

  *Mayer*; Jour. de Pharm. et de Chim., Oct. 1873; Oest Zeitsch. f.
      Pharm. ii, 232.

  *Nowak*; Dingls. poly. Jour., vol. 206, p. 422; Sitzber. d. Wiener
      Akad. d. Wissensch., 1872.

  *Otto*; Ann. Ch. Pharm. c, 39.

  *Orfila*; Jour. de. Chim. et Méd. [4] t. vii, 397.

  *Palm*; Pharm. Zeitsch. f. Russl. i, Jahxgang.

  *Pierce*; J. Chem. Soc., Nov. 1874.

  *Prollius*; Chem. Centralbl., 1857, 231.

  *Ritter*; Pharm. Zeitsch. f. Russl. 5-6 Jahrg.

  *Rodgers and Girdwood*; Jahresb. v. Liebig u. Kopp, 1857, 603; Pharm.
      Jour. Trans. xvi, 497.

  *Rorsch and Fasbender*; Deut. Chem. Gess. Ber. xii, 1064.

  *Scheibler*; Jahresb. 1863, 702; Arch. f. Pharm. lix; Jour. f. prakt.
      Chem. lxxx, 211.

  *Schneider*; Ann. Chem. Pharm., von Poggendorff, No. 9.

  *Schrage*; Archiv der Pharm., Dec., 1874.

  *Schroof*; Apothet. Jahrg., ix, 148.

  *Schulze*; Ann. Ch. Pharm. cxix, 177.

  *Schwanert*; Deut. Chem. Gess. Ber., No. 14, 1874.

  *Sonnenschein*; ibid, civ, 45.

  *Stas*; Bull. de l'Acad. Roy. de Méd. de Belgique, xi, 304 (1851);
      Ann. Ch. Pharm., lxxxiv, 379, J. Pharm. Chim., xxii, 281;
      Jahresb., 1851, 640; Jour. f. prakt. Chem., lix, 232.

  *Struve*; Zeitsch. f. anal. Chem., No. 2, 1873.

  *Thomas*; ibid, vol. i, 317.

  *v. Uslar and Erdman*; Ann. der Chem. u. Pharm., 120, p. 121; 122, p.
      360.

  *de Vrij and van der Burg*; Jahresb. v. Liebig u. Kopp, 1857, 602.

  *Watts*; Chem. Dict., vol. i, p. 125.

  *Wagner*; Fresen. Zeitsch. f. anal. Chem., iv.


On Atropine.

  *Brunner*; Archiv der Pharm., April, 1873.

  *Calmberg*; ibid. Nov., 1874.

  *Gulielmo*; Zeitsch. f. anal. Chem., ii, 404.

  *Helwig*; Wiener Akad. Ber. vii, 433.

  *Koppe*; Pharm. Zeitsch. f. Russl., 5 Jahrgang.

  *Pelikan*; ibid, 1 Jahrgang.

  *Wormley*; Chem. News, vol. ii, June, 1860.


On Brucine.

  *Cotton*; Zeitsch. f. Chem. [2] v. 728.

  *Helwig*; Zeitsch. f. anal. Chem., iii, 43.

  *Luck*; Zeitsch. f. Chem. [2] vi, 275.

  *Mayer*; Rep. Chim. app., v, 102.

  *Strecker*; Ann. Ch. Pharem., xci, 76.

  *Trapp*; Jahresb. 1863, 702.

  *Wormley*; Chem. News, vol. ii, July, 1860.


On Morphine.

  *Anderson*; Ann. Ch. Pharm., lxxv, 80.

  *Dupre*; Chem. News, viii, 267; Jahresb., 1863, 704.

  *Erdman*; Ann. Ch. Pharm. cxx, 88; ibid, cxxii, 360.

  *Flandin*; Compt. rend., xxxvi, 517.

  *Frohde*; Zeitsch. f. anal. Chem. v, 214; Arch. f. Pharm., clxxvi.

  *Huseman*; Ann. Ch. Pharm., cxxviii, 305.

  *Kalkbrunner*; Zeitsch. d. all. Oest. Apot. Ver., No. 27.

  *Lassaigne*; Ann. Ch. Pharm. [2] xxv, 102.

  *Lefert*; J. Pharm. [3] xl, 97.

  *Mermer*; J. Chim., xxiii, 12.

  *Wormley*; Chem. News, vol. ii, Sept., 1860.


On Strychnine.

  *Bingley*; Chem. Gaz., 1856, 229.

  *Brieger*; Jahresb. pr. Pharm. xx, 87.

  *Cloetta*; Zeirsch. f. anal. Chem., v, 265.

  *Davy*; J. Pharm. [3] xxiv., 204.

  *Djurberg*; Chem Centralb., 1872, 153; Zeitsch. f. anal. Chem., 1872,
      440.

  *Eboli*; Archiv der Pharm., cxxxv, 186.

  *Erdman and Marchand*; Jour. f. prakt. Chem., xxxi, 374.

  *Gorup-Besenez*; Handwörterb. [2] i, 468.

  *Graham and Hofman*; Pharm. Trans., xi, 504; Chem. Gaz., 1852, 197;
      Ann. Ch. Pharm., lxxxiii, 39.

  *Hagen*; Ann. Ch. Pharm. ciii, 159.

  *Hunefeld*; Schw., lx. 454.

  *Janssen*; Zeitsch. f. anal. Chem., 4 Jahrgang.

  *Jordan*; N. Repert., x, 156.

  *Letheby*; Pharm. J. Trans. xvi, 10.

  *Mack*; N. Br. Arch., xlvi, 314.

  *Marchand*; Chem. Gaz., June 15, 1844.

  *Mayer*; J. Pharm. [3] xlvi.

  *Reese*; Chem. News. 1862, 316.

  *Rousseau*; J. Chim. Méd. xx, 415.

  *Sonnenschein*; Jahresb. 1870, 1032; Ber. d. Deutsch. Chem. Gess. iii,
      653.

  *Schroder*; N. Br. Arch., xciii, 190.

  *Thomas*; Amer. Jour. Pharm. 1862, 227.

  *Thompson*; Pharm. J. Trans., ix., 24.

  *Vogel*; N. Repert. Pharm., ii, 560.

  *de Vrij and van der Burg*; Pharm. J. Trans. xvi, 448.

  *Wagner*; Kopp's Jahresb., 1861, 857; Zeitsch. f. anal. Chem., vi,
      387.

  *Wittstein*; Pharm. Viertelj., vi, 273.

  *Wormley*; Am. Jour. Sc. and Arts., xxviii, Sept., 1859.


On the detection of Falsifications of Writings.

  *Lucas*; Chem. Centralb., 1868, 1517.

  *Knecht-Senefelder*; Technol., xxvi, 143.

  *Moride*; Compt. rend., lviii, 367; Ding. poly. Jour. clxxii, 390.

  *Vorwerk*; Ding. poly. Jour., clxxii, 158.

  *----*; Berl. ind. Z., 1864, 41.


On the detection of adulterations in Flour and Bread.

  *Barral*; Compt. rend., lvi, 834.

  *Bastelaer*; Chem. Centralb., 1868, 1342.

  *Cailletet*; ibid, 1858, 1392.

  *Corput*; ibid, 1860, 207.

  *Crooks*; Chem. News., vol. xxxiii, 73.

  *Danckwort*; Archiv der Pharm. [2] xx, 47.

  *Davis*; Chem. News, xxv., 207.

  *Eulenberg and Vohl*; Poly. Centralb., cxcvii, 530.

  *Gobley*; Jour. de Pharm., April, 1844.

  *Hadon*; Chem. News, 1862.

  *Hager*; Ding. Poly. Jour., clxxiii, 159.

  *Harsley*; Archiv der Pharm., July and Dec., 1873; Chem. News, xxv,
      230.

  *Moitessier*; Annal. d'Hygiene, 1868.

  *Odling*; J. Soc. Arts, April 9, 1858.

  *Oser*; Ding. poly. Jour., clxxxiii, 256.

  *Rivot*; Ann. de Phys. et de Chim., 3e série t, xlvii.

  *Rummel*; Ding. poly. Jour., cxxxix, 49.

  *Tasbender*; Ding. poly. Jour., No. 6, ccvi.

  *Wanklyn*; Archiv der Pharm., Dec., 1873; Chem. News, xxxiii, No.
      736; Ber. Med. Jour., March 29, 1873.


On the examination of Fatty Oils.

  *Behrens*; Ding. poly. Jour., cxxxi, 50.

  *Calvert*; Pharm. J. Trans., xiii, 356.

  *Clarke*; Chem. News, xxiii, 145.

  *Dingl*; Poly. Jour., clxxiv.

  *Donny*; Bull. Soc. d'Erc, 1864, 372; Jahresb., 1864, 734.

  *Dragendorff*; Pharm. Zeitsch. f. Russl., ii, 434.

  *Fluckiger*; Chem. Centralb., 1871, 55.

  *Glassner*; (trans.) Am. Chem., Dec., 1873.

  *Gobley*; J. Pharm. [3], iv, 285; ibid. v. 67.

  *Jacobson*; Bull. Soc. Chim., [2] vii, 96.

  *Langlies*; Zeitsch. f. anal. Chem., 1870, 534.

  *Ludwig*; Archiv der Pharm., [3] i, 1.

  *MacNaught*; Chem. Centralb., 1862, 742.

  *Massie*; Zeitsch. f. anal. Chem., 1871, 495.

  *Maumene*; Compt. rend., xxxv, 572.

  *Nickles*; Bull. Soc. Chim., [2] vi, 89

  *Penot*; Bull. de Mullh., xxvi, 7; Jahresb., 1866, 827.

  *Roth*; Bull. de Mullh., 1864, 104.

  *Ure's* Dict. of Arts, etc., iii, 300.

  *Vogel*; Chem. Centralbl., 1863, 945.

  *Watt's* Dict. of Chem., iv., 182.


On the examination of Milk.

  *Boussingault*; Ann. Chem. Phys. [4] xxv, 382.

  *Baumhauer*; J. pr. Chem., lxxxiv, 145.

  *Casselman*; Chem. Centralb., 1863, 689.

  *Dancer*; Chem. News, v, 21, p. 51.

  *Daubrawa*; Jour. f. prakt. Chem., lxxviii, 426.

  *Donne*; Compt. rend., xvii, pp. 585, 591.

  *Filhol and Joly*; Wurtz's Dict. de Chim., t. ii, p. 195.

  *Gmelin*; Handb. der Chem., viii, [2] 246-273.

  *Heeren*; Chem. Centralb., 1870, 304.

  *Hermstaedt*; Pharm. Centralb., 1833, 401.

  *Kletzinsky*; Chem. Centralb., 1861, 244.

  *Lade*; Chem. Centralb., 1858, 144.

  *Leconte*; ibid, 1854, 1465.

  *Lehman*; Lehrb. der Phys. Chem., 1863, ii, pp. 287, 301; (trans. by
      Day) ii, pp. 449, 475.

  *Macadams*; Am. Chem., May, 1875, 419.

  *Marchand*; Jour. de Pharm., Nov., 1854.

  *Michaelson*; Ding. poly. Jour., cxlix, 59.

  *Millon*; Compt. rend., lix, 396.

  *Muller*; Zeitsch. f. anal. Chem., No. 3, 1872.

  *Otto*; Ann. Chem. Pharm., cii, 47.

  *Pelouze and Fremy*; Traité de Chim. gen., [2 edit.] Paris, 1857, p.
      195.

  *Pribram*; Dings. poly. Jour., cxcvii, 448

  *Reichelt*; Bayr. K. u. Gwbl., 1859, 602.

  *Reineck*; Ding. poly. Jour., cci, 433.

  *Rosenthal*; Chem. Centralb., 1854, 1392.

  *Seely*; Sill. Am. J., vii, 293.

  *Vernois and Becqueret*; Ann. d'Hygiéne, April, 1853.

  *Voelcker*; Am. Chem., May, 1875, p. 412.

  *Vogel*; Poly. Notizbl., No. 10, 1874.

  *Wanklyn*; Pharm. Viertelj., xx, 201: Milk Jour., 1, 109, 160; Chem.
      News, xxviii, No. 623; ibid, No. 736; Pharm. Journ. Trans., [3] i,
      605.


On the detection of adulteration in Wine and Beer.


WINE.

  *Beck*; Edinb. Phil. Jour., 1835.

  *Berthelot and Fleurien*; Compt. rend., lvii, 394.

  *Blume*; Dings. poly. Jour., clxx, 240.

  *Bolly and Paul*; Manual of Tech. Anal., p. 331.

  *Boyer and Coulet*; Compt. rend., lxxvi, 585.

  *Brande*; Phil. Trans., 1811.

  *Cotlini*; Ann. du Genie Civil, No. 3, 1873.

  *Cotlini and Fantazini*; Ann. di Chim. Appl. alla Medi., Juli, 1870.

  *Christison*; Edinb. Phil. Jour., 1838.

  *Diez*; Ann. Ch. Pharm., xcvi, 304.

  *Duclaux*; Ann. de Chim. et de Phys., July and Sept., 1874; Compt.
      rend. lxxviii, 1159.

  *Duffield*; Am. Jour. Pharm., Mar. 1862.

  *Dupre*; Chem. Soc. Jour. xx, 493.

  *Fantenelle*; J. Chim. Méd., iii, 332.

  *Faure*; J. Pharm., vii, 200.

  *Fischern*; Ann. Chem. Pharm., lviii, 705.

  *Fresenius*; ibid, lxiii, 384.

  *Geiger*; Mag. f. Pharm., xix, 266.

  *Geromont*; Ann. Ch. Pharm., xvii, 158.

  *Hager*; Zeitsch. f. anal. Chem., 1872, 337.

  *Hitchcock*; Edinb. Phil. Jour., xxxvii, 176.

  *Jacquemin*; Ann. de Chim. et de Phys. v, série, Nov., 1874; Compt.
      rend., lxxix, 523.

  *Kersting*; Ann. Ch. Pharm., lxx, 50.

  *Khol*; J. Chim. Méd., [4] ii, 251.

  *Liebig, Poggendorff and Wohler*; Handwörterb. ix, 676.

  *Ludersdorf*; J. f. prak. Chem., xxiv, 102.

  *Maisch*; Proc. Am. Pharm. Assn., 1863, 296; 1864, 291; 1866, 267.

  *Mallard*; J. Chim. Méd., iii, 326.

  *Maumene*; Bull. Soc. Chim., xxii, No. 1.

  *Miller*; Jour. de Pharm. et de Chim., Mar., 1873.

  *Mitis*; Baierisch. K. u. Gewerbeblatt, 1838.

  *Phipson*; Zeitsch. f. anal. Chem., ix, 121.

  *Reiman's* Farb. Zeit., Nos. 14-15, 1874.

  *Romei*; Mon. Scien., iii, t. iii, No. 382.

  *Salleron*; Compt. rend., lxxviii, No. 16.

  *Scheitz*; Arch. Pharm., [3] v, 331.

  *Schubert*; Pogg. Annal., lxx, 397.

  *Sestini*; Landwirthsch. Ver. Stat., xv, 9.

  *Tuchschmeidt*; Jahresb., 1871, 967.

  *Zierl*; Baierisch. Kunst. Gewerbebl, 1838.


BEER.

  *Blas*; Viertelj. f. prakt. Pharm., xxi, 584.

  *Brunner*; Archiv der Pharm., April, 1873; Dings. poly. Jour., ccix,
      No. 6; Jour. de Pharm. et de Chim., Sept., 1873; Poly. Nolizblatt,
      No. 17, 1873.

  *Dietz*; Neues Jahresb. f. Pharm., xxxix, No. 1.

  *Dragendorff*; Archiv. der Pharm., April and May, 1874; Dings. poly.
      Jour., ccxiv, pp. 33, 389.

  *Dullo*; Wieck's Gaz., 1865, 64.

  *Gunckel*; Arch. f. Pharm., clxiv.

  *Kubinki*; Le Technol, No. 397; (trans.) Amer. Chem., Nov., 1874;
      Dings. poly. Jour. ccxi, 360.

  *Langley*; Chem. Centralb., 1865, 184.

  *Meme*; Compt. rend., 2me sem., No. 123.

  *Michælis*; Ill. Gewerbz., 1871, 8.

  *Muspratt's* Chem. i, 281.

  *Pohl*; Wiener Akad. Ber., xii, 88.

  *Ritter*; Pharm. Zeitsch. f. Russl., i, pp. 304, 414.

  *Shafhauel*; Ding. poly. Jour., cxxxii, 299.

  *Schmidt*; Jour. f. prakt. Chem., lxxxvii, 344.

  *Stolber*; ibid, xciv, iii.

  *Ure's* Dict. Chem., 4th edit., 1831, p. 203.

  *Vogel and Hammon's* Mitth., 1860, 184.

  *Wittstein*; Archiv der Pharm., Jan. 1875.


On the testing of Vinegar.

  *Bussy and Buignet*; Jahresb., 1865, 69.

  *Greville*; Ding. poly. Jour., cxxxi, 139.

  *Liebig, Poggendorff and Wohler*; Handwörterb, ii, 867.

  *Mohr*; Ann. Ch. Pharm., xxxi, 277.

  *Mollerat*; Ann. Chim., lxviii, 88.

  *Nicholson*; Ding. pol. Jour., cxxxix, 441.

  *Otto*; Ann. Chem. Pharm., cii, 69.

  *Roscoe*; Chem. Soc. Jour., xv, 270.

  *Runge*; Gewz. Bayer. 1871, 4.

  *Strohl*; Jour. de Pharm. et de Chim., Sept., 1874.

  *Toorn*; Jour. f. Chem., vi, 171.

  *Wagner*; Chem. Tech., (English trans.) p. 467.

  *Williams*; Pharm. J. Trans., xiii, 594.


On the detection of adulterations in Sulphate of Quinine.

  *Delondre and Henry*; J. Pharm., [3] xxi, 281.

  *Gmelin's* Handbuch, xvii, 280.

  *Guibourt*; J. Pharm., [3] xxi, 47.

  *Henry*; ibid, xiii, 107.

  *Hesse*; Ann. Ch. Pharm., cxxxv, 325; Jahresb., 1865, 441.

  *Korner*; Zeitsch. f. Chem., J. i, 150; Jahresb. 1862, 619.

  *Phillips*; Lond. Lanc., i, 820.

  *Riegel*; Jahresb. f. Pharm., xxv, 340.


On the detection of Blood Stains.

  *Barruel*; Ann. d'Hygiéne pub., i. 267; ibid, No. 6, 1829.

  *Bertolet*; Am. Jour. Med., Sc., Jan., 1874.

  *Brucke*; Jahresb., 1857, 609.

  *Van Deen*; Zeitsch. f. anal. Chem., ii, 459.

  *Erdman*; Jour. pr. Chem., lxxxv, 1; Jahresb., 1862, 634.

  *Falck*; Ber. Klinisch. Wochb., 1872.

  *van Geuns and Gunning*; Zeitsch. f. anal. Chem., 1871, 508.

  *Gwosden*; Wiener Akad. Ber., liii, [2] 683; Jahresb., 1866, 746.

  *Helwig*; Zeitsch. f. anal. Chem., 1872, 244.

  *Hirsch*; N. J. Pharm., xxxii, 140.

  *Hoppe-Seyler*; Med. Chem. Unters., i, 298; Jahresb., 1867, 805.

  *Krauss*; Jahresb., 1861, 792.

  *Liebig, Poggendorff and Wohler*; Handwörterb., iv, 177.

  *Liman*; Jahresb., 1863, 715.

  *Lowe*; Pharm. Centralb., 1854, 137.

  *Mandl*; Lond. Lanc., Dec. 17, 1842, 176.

  *Muller*; Zeitsch. f. anal. Chem., 1872, iii.

  *Orfila*; Jour. des Progés des Sc., iv, 1827; Archiv. gen. de Méd.,
      Fev., 1828.

  *Papillon*; Mon. Scien. Ques., Jan., 1874, 59.

  *Reynolds*; Br. Med. Jour., Jan. 4, 1873.

  *Rose*; Jahresb. der Pharm., ii, 365; Jahresb., 1854, 754.

  *Roussin*; Ann. d'Hyg. et de Méd. lég., 1865.

  *Scriba, Simon and Buchner*; Jahresb., 1859, 706.

  *Sonnenschein*; Jour. de Pharm. et de Chim., July, 1874; Mon. Scien.,
      ii, 370.

  *Sorby*; Chem. News, 1865, xi, pp. 186, 194, 232, 256.

  *Struve*; Zeitsch. f. anal. Chem., 1872, 29.

  *Taylor*; Guy's Hosp. Rep., 1868.

  *Wicke*; Pharm. Centralb., 1854, 431.

  *Wittstein*; Arch. der Pharm., ii, 128.

  *Zollikopfer*; Ann. d. Chem. u. Pharm., xciii, 237; Pharm. Centralb.,
      1855, 217.


On the detection of Spermatic Stains.

  *Bayard*; Ann. d'Hygiéne. pub., 1849, No. 43.

  *Renak*; Diagnostisch. u. Pathologisch. Unters. Berlin, 1845, pp. 148,
      171.

  *Schmidt*; Diagnostik Verdäch. Flecken, Leipzig, 1848, pp. 42-48.

       *       *       *       *       *

The following are the most important works relating to poisons and
food-adulteration that have been issued since the publication of the
first edition of this book:

  *Adam*; Étude sur les principales methodes d'essai et d'analyse du
      lait.                                                 Paris, 1879.

  *Averbeck*; Die Verfälschung der Nahrungsmittel.         Bremen, 1878.

  *Bastide*; Vins sophistiqués.                            Beriès, 1876.

  *Bauer*; Die Verfälschung der Nahrungsmittel.            Berlin, 1877.

  *Bell*; Analysis and adulteration of food.                       1881.

  *Binz*; Intoxicationen.                                Tübingen, 1878.

  *Birnbaum*; Einfache Methoden zur Prüfung Lebensmittel.          1877.

  *Blane*; De la contrefaçon.

  *Blas*; De la présence de l'acide salicylique dans les bierres.
                                                            Paris, 1879.

  *Blochman*; Ueber Verfälschung der Nahrungsmittel.   Königsberg, 1881.

  *Blyth*; Dictionary of Hygiene.                          London, 1877.

  _Ibid_; Manual of chemistry.                             London, 1879.

  _Ibid_; Foods, composition and analysis.                 London, 1882.

  _Ibid_; Poisons, effects and detection of.               London, 1882.

  *Boehn*; Herzgifte.

  *Bolley*; Manuel pratique d'essai et de recherches chimiques.
                                                            Paris, 1877.

  *Bronner*; Chemistry of food and drink.                        London.

  *Caldwell*; Agricultural chemical analysis.               N. Y., 1879.

  *Casper*; Handbuch der gerichtlichen Medizin.            Berlin, 1881.

  *Church*; Food.                                           N. Y., 1877.

  *Cooley's* Practical receipts.

  *Dannehl*; Die Verfälschung des Bieres.                  Berlin, 1877.

  *Dietzsch*; Die wichtigsten Nahrungsmittel, etc.         Zurich, 1878.

  *Dragendorff*; Recherches des substances amères dans la bière.
                                                            Paris, 1876.

  _Ibid_; Gerichtlich chemische Ermittellung von Giften.
St. Petersburg, 1876.

  *Elsner*; Die Praxis Nahrungsmittel Chemikers.          Leipzig, 1880.

  *Eulenberg*; Handbuch der Gewerbe-Hygiene.               Berlin, 1876.

  *Falk*; Lehrbuch der praktischen Toxicologie.         Stuttgart, 1880.

  *Flick*; Die Chemie im Dienst der öffentlichen Gesundheitspflege.
                                                          Dresden, 1882.

  *Fluegge*; Lehrbuch der hygienischen Untersuchungsmethoden.
                                                          Leipzig, 1881.

  *Focke*; Massregeln gegen Verfälschung der Nahrungsmittel.
                                                         Chemnitz, 1877.

  *Fox*; Sanitary examination of water, air, and food.             1878.

  *Franchini*; Palmelle prodigieuse.                      Bologne, 1880.

  *Gamgee*; Text-book of physiological chemistry.          London, 1880.

  *Gaultier*; La sophistication des vins.                   Paris, 1877.

  *Gimlini*; Experimentelle Untersuchung über die Wirkung des Aconitins.
                                                         Erlangen, 1876.

  *Goppelsroeder*; Sur l'analyse des vins. Mulhouse, 1877.

  *Grandeau*; Handbuch für agricultur-chemische Analysen.  Berlin, 1880.

  *Griessmayer*; Die Verfälschung der wichtigsten Nahrungs-und
      Genussmittel.                                                1880.

  *Hahn*; Die wichtigsten d. his jetzt bekannten Geheimmittel u.
      Specialitäten.                                               1876.

  *Hausner*; Fabrikation der Conserven und Conditen.      Leipzig, 1877.

  *Hemming*; Aids to forensic medicine and toxicology.     London, 1877.

  *Hilger*; Die wichtigsten Nahrungsmittel.              Erlangen, 1879.

  *Hoffman*; Lehrbuch der gerichtlichen Medizin.             Wien, 1880.

  *Hoppe-Seyler*; Physiologische Chemie.                   Berlin, 1878.

  *Husson*; Du vin.                                         Paris, 1877.

  _Ibid_; Le lait, la créme, et le beurre.                         1878.

  *Johnson's* Encyclopædia, vol. iv. p. 752.

  *Johnson*; Chemistry of common life.                      N. Y., 1880.

  *Judell*; Die Vergiftung mit Blausäure.                Erlangen, 1876.

  *Kensington*; Analysis of foods.                         London, 1879.

  *Klencke*; Illustrirtes Lexicon der Verfälschung der Nahrungsmittel
      und Getränke.                                       Leipzig, 1878.

  *Koenig*; Chemische Zusammensetzung der menschlichen Nahrungsmittel.

  *Lang*; Die Fabrikation der Kunstbutter, Sparbutter, und Butterin.
                                                                   1878.

  *Lessner*; Atlas der gerichtlichen Medizin.              Berlin, 1883.

  *Lieberman*; Anleitung zur chemischen Untersuchung auf der Gebiete
      der Medicinal-polizei.                            Stuttgart, 1877.

  *Lintner*; Lehrbuch der Bierbrauerei.                            1877.

  *Loebner*; Massregeln gegen Verfälschung der Nahrungsmittel.
                                                         Chemnitz, 1877.

  *Luerssen*; Medicinisch Botanik.                        Leipzig, 1883.

  *Maschka*; Handbuch der gerichtlichen Medizin.         Tübingen, 1882.

  *Medicus*; Gerichtlich-chemische Prüfung von Nahrungs-und
      Genussmitteln.                                               1881.

  *Montgomery*; Essai de Toxicologie.                       Paris, 1878.

  *Muter*; A key to organic materia medica.                        1879.

  *Ogston*; Lectures on medical jurisprudence.             London, 1878.

  *Palm*; Die wichtigsten und gebrauchlichsten Nahrungsmittel.
                                                   St. Petersburg, 1882.

  *Parkes*; Hygiene.                                       Phila., 1878.

  *Pasteur*; Études sur la bière.                           Paris, 1876.

  *Pavy*; A treatise on food and dietetics.                London, 1875.

  *Pennetier*; Leçons sur les matières premières organiques.
                                                            Paris, 1881.

  *Praag*; Leerbock voor practische Giftleer.                   Utrecht.

  *Pratt*; Food adulteration.                             Chicago, 1880.

  *Prescott*; Proximate organic analysis.                   N. Y., 1882.

  *Ritter*; Des vins colorés par la fuchsine.               Paris, 1876.

  *Reitleitner*; Die Analyse des Weines.                     Wien, 1877.

  *Schnacke*; Wörterbuch der Verfälschung.                   Jena, 1877.

  *Schmidt*; Anleitung sanitarisch-und polizeilich-chemischen
      Untersuchungen.                                      Zurich, 1878.

  *Schroff*; Beitrag zur Kenntniss des Aconits.              Wien, 1876.

  *Selmi*; Chimica applicata all' igiene alla economia domestica. Milan.

  *Sharples*; Food and its adulteration.                  Preston, 1879.

  *Smith*; On foods.                                        N. Y., 1873.

  *Smith, Ed.*; Manual for medical officers of health.     London, 1874.

  _Ibid_; Handbook for inspectors of nuisances.                  London.

  *Spon's* Encyclopædia. London, 1882.

  *Squibb*; Proper legislation on adulteration of food.     N. Y., 1879.

  *Steirlin*; Ueber Weinverfälschung und Weinfarbung.        Bern, 1877.

  _Ibid_; Das Bier und seine Verfälschung.                   Bern, 1878.

  *Thudicum and Dupre*; Wine.

  *Vogel*; Praktische Spectral-analyse.                Nordlingen, 1877.

  *Wanklyn*; Tea, coffee, and cocoa.                       London, 1874.

  *Wanklyn and Cooper*; Bread analysis.                    London, 1881.

  *Wenyl*; Analytisches Hülfsbuch.                         Berlin, 1882.

  *Wittstein*; Taschenbuch des Nahrungs-und Genussmittel Lehre.
                                                       Nordlingen, 1877.

  *Woodman*; Handbook of forensic medicine.                London, 1877.

  *Wurtz*; Traité élémentaire de chimie médicale.                 Paris.


MEMOIRS.


Alkaloids.

  Journal Chem. Soc. i, 1877, p. 143; ibid, i, 1878, p. 151; ibid, May,
    1882; ibid, ccxliv, 1883, p. 358.

  Trans. Internat'l Med. Cong., 1881, vol. i, p. 472.

  Virch., Arch. bd. 79, 1880, s. 292; ibid, bd. 87, 1882, s. 410.

  Archiv. d. Pharm., Jan. 7, 1882; ibid, [3] vii, pp. 23-26; ibid, [3]
    vi, p. 402.

  Liebig, Anal. bd. 708, 1881.

  Berl. Klin. Wochenschr. 1876, 27.

  Pflüger's, 23, 433.

  Lancet, Sept. 30, 1880; ibid, Nov. 28, 1882; ibid, Nov. 13, 1882.

  Bull. Farm. Milano, 1881, p. 197.

  Zeitsch. f. Anal. Chem. i, 517.

  Gazett. Chim. Ital. vi, 153-166.

  Pharm. Zeitschr. f. Russland, i, p. 277.

  Vierteljahrsschr. f. gericht. Med. xxiii, p. 78.


Arsenic and Antimony.

  Archiv, f. exper. Path. u. Pharm., Leipzig, 1882.

  Pharm. Journ. Trans. [3] pp. 81-83.

  Med. Jahrbuch, 1880.

  Journ. d'Hygiène, Juil., 1878.

  Medical Times and Gaz. 1876, p. 367.

  Chem. News, Jan., 1881, p. 21; ibid, xxxiii., pp. 58 and 74.

  Am. Chem. Journ. ii, No. 4.

  Bull. Soc. Chim. [2] xxvi, p. 541; ibid, Jan. 7, 1877.

  Zeitsch. f. Anal. Chem. xiv, pp. 250, 281, 356; ibid, i, p. 445.

  Liebig, Anal. ccvii, p. 182.

  Lancet, 1879, p. 699; ibid, May 19, 1883.

  Journ. Chem. Soc. No. 1, 1876.


Mercury, Copper and Lead.

  Zeit. f. Phys. Chem. 1882, i, p. 495.

  Analyst, 1878, p. 241.

  Chem. News, xxxi, p. 77; ibid, xxxi, p. 801; ibid, xxxiv, pp. 176,
    200, and 313.

  Analyst, 1877, pp. 13 and 216.

  Journ. Chem. Soc. 1876, ii, p. 4.

  Dingl. Pol. Journ. ccxx, 446.

  Med. Gazette, xlviii, 1047.


Prussic Acid.

  Analyst, Apr., 1877, p. 5.

  Bull. Gen. de Thér. No. 30.

  Am. Journ. Phys. Sci., Arnold, 1869.

  Virch., Arch. f. Path. Anat. bd. 38, p. 435.

  News Repert. f. Pharm., 18, 356.

  Journ. Chem. Soc. 1876, i, p. 112.

  Bericht. d. Deutsch. Chem. Gess. ix, p. 1023.

  Viertelj. f. Ger. Med. 1881, p. 193.

  Zeit. f. Anal. Chem. von Fresenius, xii, p. 4.


Flour and Bread.

  Analyst, June, 1878; ibid, Jan., 1882; ibid, 1878, No. 28; ibid, vi,
    1879, p. 126; ibid, iii, pp. 274, 355.

  Chem. News, 1873, 1879, xxxix, p. 80.

  Dingl. Pol. Journ. bd. 209.

  Journ. Pharm. [4] iv, 108.

  Chem. Centr'b't, 1877, 585.

  Pharm. Journ. xiii, 857.

  Journ. Chem. Med. 1878, p. 240.

  An. d. Chem. u. Pharm, bd. 10, 45 u. 101.

  Journ. f. Pract. Chem. xcix, 296; ciii, 65, 193, 233, 273.

  Zeit. Anal. Chem. 1878, p. 440; ibid, 1879, vol. xviii, p. 120.

  Chem. Soc. Jour. xxxv, p. 610.

  Jour. d'Hygiène, May, 1878.

  Pharm. Jour. Trans. 1876, cccxii, 1001.

  Pharmacographia, 1879, p. 62.

  Sanitary Engineer, vol. v, p. 66.


Tea.

  Pharm. Journ. 1873; 3d series, 1874.

  Chem. News, xxx, 1874 (Allen); xxx, 125; xxviii, 186.

  Journ. Pharm. [2] xxvi, 63; xii, 234, 229.

  Analyst, June, 1877; 1876 (Wigner).

  Journ. Chem. Soc. 1875, 385, 1217; ix, 321, 33; 1858.

  Journ. f. Pract. Chem. x, 273; xciv, 65; li, 401.

  Bull. Soc. Chim. [2] xxvii, 199.

  Journ. de Pharm. d'Anvers, 1876, 121.

  Journ. Pharm. et Chim. 3 série, 1856, xxiv, 228.

  Repert. de Pharm. 1856, vii, p. 117.

  Journ. Chim. Méd. 2 série, 1844, x, 459; 1844, 24.

  Ann. Chem. Pharm. xxvi, 244; xxix, 271; xxxvi, 93.

  Ann. Chem. Pharm. lxxxii, 197; cxii, 96; i, 19; 1, 231; lxiii, 201;
    lxix, 120; lxxi; cxviii, 151.

  Ann. Chem. xxv, 63.

  Med. Press and Circular, 1871, p. 415.

  Kastu. Arch. vii, 266.

  Deut. Chem. Ges. Ber. ix, 1312.

  Parliamentary papers, 1871.

  Mag. Pharm. xix, 45.

  Ann. Chim. Phys. [3] xi, 138.

  Schweigg, Journ. Chem. Phys. lxi, 487; lxiv, 372.

  Phil. Mag. J. xxiii, 426; xiii, 21.


Milk.

  Analyst, 1876, Jan. and May; 1877, p. 82; No. 21; Sept., Dec.; 1878,
    Jan.; p. 249; 1880, Mar.

  Chem. News, 1879.

  Journ. Chem. Soc. clxxxix, Sept., 1878.

  Comptes Rendus, t. 82, 1876.

  Ann. Chem. Pharm. lxi, 221.

  Milch Zeit. 1870, 1884.


Wine and Beer.

  Analyst, 1877, pp. 26, 99, 146, 148.

  Ann. Chim. Phys. [5] ii, pp. 233-289.

  Bull. Soc. Chim. [2] xxv.

  Deut. Chem. Ges. Ber. ix, 1900.

  Comptes Rendus, lxxxiv, 348.

  Journ. Chim. Méd. t. ix, p. 495.

  Arch. Pharm. [3] v. 25, 23, bd. 185, p. 225.

  Chem. Soc. Journ. ii, 1877, p. 372.

  Ann. d'Hyg. et Méd. Lég. 1861, xvii, pp. 33, 430.


Vinegar.

  Analyst, iii, 1878, p. 268; i, 1877, p. 105.

  Ann. d'Hyg. et Méd. Lég. 2 sér. t. xii.

  Pharm. Journ., Jul. 3, 1875.

       *       *       *       *       *

Within the last few years the subject of food-adulteration has been so
prominently brought before the public that, in many instances, the
various State Boards of Health have commissioned their chemists to
furnish reports on this subject. These may be found in the annual
publications of the same, notably in the volumes issued by the
Massachusetts, Michigan, New Jersey, and New York State Boards of
Health. It may also be mentioned in this connection that the _Sanitary
Engineer_ of New York, the _Analyst_ of London, the _Zeitschrift für
Untersuchung von Lebensmitteln_, Eichstatt, and the _Zeitschrift gegen
Verfälschung der Lebensmittel_, Leipzig, are journals devoted to the
consideration of adulterations and the more recent methods employed for
their detection.

  J. P. B.




INDEX.


  A.

  Acetic Acid, 49, 89

  Acids, 46, 95
    Acetic, 49, 89
    Boric, 90
    Formic, 89
    Hydriodic, 90
    Hydrobromic, 90
    Hydrochloric, 46
    Hydrocyanic, 50
    Hydrofluoric, 88
    Hydrosulphuric, 91
    Nitric, 47, 88
    Oxalic, 49, 88, 89, 95
    Phosphoric, 48, 90, 95
    Phosphorous, 45
    Sulphuric, 47, 89, 95

  Aconitine, 79

  Alcoholmeter (Gay-Lussac's), 145

  Alkalies, 32, 93
    Ammonia, 50
    Baryta, 54
    Lime, 53
    Potassa, 53
    Soda, 53
    Strontia, 54

  Alkaloids, 65
    Aconitine, 79
    Aniline, 75
    Aricine, 77
    Atropine, 80
    Beberine, 76
    Brucine, 78
    Cinchonine, 78
    Codeine, 80
    Colchicine, 80
    Conine, 75
    Delphine, 78
    Digitaline, 80
    Emetine, 80
    Morphine, 80
    Narcotine, 77
    Nicotine, 75
    Papaverine, 77
    Picrotoxine, 80
    Quinine, 77
    Solanine, 79
    Strychnine, 78
    Veratrine, 77

  Alkaloids, separation of, by Stas's method, 65
    Separation of, by Otto's method, 69
    Separation of, by v. Uslar and Erdman's method, 70
    Separation of, by Rodgers & Girdwood's method, 71
    Separation of, by Prollius's method, 72
    Separation of, by Graham & Hofman's method, 73
    Separation of, by Dialysis, 74

  Alkaloids, identification of, 74

  Alloys, examination of, 112

  Alum in flour and bread, 126

  Aniline, 75

  Antimony, 30, 62, 93
    Detection of, by Flandin and Danger's method, 32
    Detection of, by Naquet's method, 34

  Aricine, 77

  Arsenic, 17, 60, 93
    Detection of, by the method used prior to Marsh's test, 17
    Detection of, by Marsh's test, 21
    Detection of, by Raspail's test, 29
    Detection of, by Reinsch's test, 30

  Arsenic, estimation of, 21

  Ashes, examination of, 104

  Atropine, 80


  B.

  Barley meal in flour, 117

  Baryta, 54

  Barreswil's test for milk, 140

  Berberine, 76

  Bicarbonate of soda in milk, 141

  Bismuth, 62

  Blood stains, detection of, 150

  Bleaching of hair, 98

  Boric acid, 90

  Boutigny's examination of fire-arms, 100

  Bromine, 55, 90, 93, 94

  Brücke's test for blood stains, 152

  Brucine, 78

  Buckwheat in flour, 117, 120


  C.

  Cadmium, 63

  Carbonate of lime and magnesia in flour, 125

  Cerebral substances in milk, 142

  Chalk in milk, 141

  Chlorine, 54

  Chromium, 64

  Cinchonine in sulphate of quinine, 149

  Codeine, 80

  Conine, 75

  Coins, examination of, 112

  Colchicine, 80

  Copper, 62, 63

  Corn meal in flour, 117, 120


  D.

  Darnel in flour, 121

  Delphine, 78

  Determinative tests for poisons, 94

  Digitaline, 80

  Dusart's test for phosphorus, 40

  Dialysis, 15, 74

  Dyeing of hair, 97


  E.

  Emetine, 80

  Emulsion of almonds in milk, 141


  F.

  Fire-arms, examination of, 100
    Weapons provided with a flint, 100
    Weapons not provided with a flint, 103

  Fixed Oils, examination of, 128
    Hempseed, 130
    Olive, 128

  Flandin and Danger's test for antimony, 32

  Flandin and Danger's test for mercury, 37

  Food (flour and bread), 114
    Examination of the gluten, 116
    Examination of the starch, 118
    Examination of the ash, 124

  Formic acid, 89

  Fresenius & Neubauer's test for phosphorus, 42


  G.

  Galactoscope, 138

  Graham and Hofman's method for alkaloids, 73

  Ground bones in bread and flour, 125

  Gum arabic in milk, 141

  Gum tragacanth in milk, 141


  H.

  Hæmin crystals, 150

  Hair, examination of, 96

  Hempseed oil, 130

  Hoppe-Seyler's test for blood, 151

  Hydriodic acid, 90

  Hydrobromic acid, 90

  Hydrochloric acid, 46, 91

  Hydrocyanic acid, 50

  Hydrofluoric acid, 88

  Hydrosulphuric acid, 91


  I.

  Iodides, 90, 94

  Iodine, 56, 94

  Indicative tests for poisons, 36


  L.

  Lactodensimeter, 138

  Lactometer, 139

  Lactoscope, 138

  Lassaigne's test for writings, 107

  Lead, 57

  Legumens in flour, 117, 121, 124

  Lentils in flour, 123

  Lime, 53

  Lime in flour, 126

  Linseed meal in flour, 120


  M.

  Macadam's method for alkaloids, 73

  Magnesia in sulphate of quinine, 148

  Mannite in sulphate of quinine, 148

  Marchand's test for milk, 139

  Marsh's test for arsenic, 21

  Mercury, 36, 62, 93
    Detection of, by Smithson's pile, 36
    Detection of, by Flandin and Danger's method, 37

  Metals, 56
    Antimony, 30, 62, 93
    Arsenic, 17, 60, 93
    Bismuth, 62
    Cadmium, 63
    Chromium, 64
    Copper, 62, 63
    Lead, 57
    Mercury, 36, 62, 93
    Silver, 57
    Tin, 56, 61
    Zinc, 64

  Milk, examination of, 137

  Mineral substances, in flour and bread, 124
    In milk, 141
    In sulphate of quinine, 148

  Mistcherlich's test for phosphorus, 40

  Morphine, 80


  N.

  Naquet's test for antimony, 34

  Narcotine, 77

  Nicotine, 75

  Nitric acid, 47, 88


  O.

  Oatmeal in flour, 117

  Oleometer, 128

  Olive oil, 128

  Orfila's test for phosphorus, 39

  Organic matter
    Destruction of, by _aqua regia_, 14
    Destruction of, by chlorate of potassa, 13
    Destruction of, by chlorine, 13
    Destruction of, by nitrate of potassa, 10
    Destruction of, by nitric acid, 8
    Destruction of, by potassa and nitrate of lime, 12
    Destruction of, by potassa and nitric acid, 12
    Destruction of, by sulphuric acid, 9

  Otto's method for alkaloids, 69

  Oxalic acid, 49, 88, 89, 95


  P.

  Papaverine, 77

  Payen's test for vinegar, 147

  Phosphoric acid, 48, 90, 95

  Phosphorous acid, 45

  Phosphorus, 39, 95
    Detection of, by Orfila's method, 39
    Detection of, by Mistcherlich's method, 40
    Detection of, by Dusart's method, 40
    Detection of, by Fresenius and Neubauer's method, 42
    Estimation of, 45

  Picrotoxine, 80

  Plaster in flour, 126

  Poisons, detection of
    In cases where no clew exists, 85
    In cases where a clew exists, 17
    Destruction of the organic matter, 8
    Indicative tests, 86
    Determinative tests, 94

  Potato meal in flour, 118

  Potassa, 53, 93

  Prollius' method for alkaloids, 72

  Prussic acid, 50


  Q.

  Quinine, 77


  R.

  Raspail's test for arsenic, 29

  Reinsch's test for arsenic, 30

  Reveil's test for vinegar, 148

  Rice meal in flour, 120

  Robin's method for spermatic stains, 160

  Rodgers and Girdwood's method for alkaloids, 71

  Rye meal in flour, 117, 120


  S.

  Salicine in sulphate of quinine, 148

  Sand in flour, 125

  Silver, 57

  Smithson's pile, 36

  Soda, 53, 92, 93

  Solanine, 79

  Spermatic stains, detection of, 158

  Spermatozoa, 159

  Starch in sulphate of quinine, 148

  Stearic acid in sulphate of quinine, 148

  Stas's method for alkaloids, 65

  Strychnine, 78

  Sugar in milk, 142

  Sugar in sulphate of quinine, 148

  Sulphate of copper in bread, 127

  Sulphate of quinidine in sulphate of quinine, 149

  Sulphate of quinine, examination of, 148

  Sulphuretted hydrogen, 91

  Sulphuric acid, 47, 89, 95

  Sympathetic inks, tests for, 110


  T.

  Tea, 130

  Tin, 56, 61


  U.

  v. Uslar and Erdman's method for alkaloids, 70


  V.

  Veratrine, 77

  Vinegar, examination of, 147


  W.

  Wines, examination of, 142

  Writings, examination of, 105


  Z.

  Zinc, 64




  BECKER & SONS,
  MANUFACTURERS OF
  Balances and Weights of Precision,
  FOR

  [Illustration]

  Chemists, Assayers, Jewelers, Druggists,
  _And in general for every use where accuracy is required_,
  No. 6 Murray St., New York.

Every Balance and Set of Weights leaving this establishment is
guaranteed to be accurately adjusted, as represented in our Price List.

--> Our Illustrated Price List mailed on application.




CATALOGUE

OF THE

SCIENTIFIC, MILITARY, AND NAVAL

PUBLICATIONS

OF

D. VAN NOSTRAND,

23 Murray Street and 27 Warren Street, New York.



*ABBOT, Maj. HENRY L.--Siege Artillery against Richmond.*

  Illustrated. 8vo, cloth                                          $3 50

*ADAMS, J. W.--Sewers and Drains for Populous Districts.*

  Embracing Rules and Formulas for the dimensions and construction of
  works of Sanitary Engineers. Second edition. 8vo, cloth           2 50

*ALDRICH, M. ALMY.--History of the United States Marine Corps.*

  From Official Reports and other Documents. Compiled by Capt. Richard
  S. Collum. 8vo, cloth                                             2 50

*ALEXANDER, J. H.--Universal Dictionary of Weights and Measures*,
    Ancient and Modern, reduced to the Standards of the United States of
    America.

  New edition, enlarged. 8vo, cloth                                 3 50

*ANDERSON, Gen. ROBERT.--Evolutions of Field Batteries of Artillery.*

  Translated from the French, and arranged for the Army and Militia of
  the United States. Published by order of the War Department. 33
  plates. 24mo, cloth                                               1 00

*ANDREWS, Maj.-Gen. C. C.--Campaign of Mobile.*

  Including the Co-operation of General Wilson's Cavalry in Alabama.
  With five maps and views. 8vo, cloth                              2 50

---- *Hints to Company Officers on their Military Duties.*

  18mo, cloth                                                         50

*ARNOLD, Maj. A. K.--Cavalry Service.*

  Notes on Horses for Cavalry Service, embodying the Quality, Purchase,
  Care, and Diseases most frequently encountered, with Lessons for
  Bitting the Horse and Bending the Neck. Illustrated. 18mo, cloth    75

*ARNOLD, Maj. FRANK S.--The Discipline and Drill of Militia.*

  Crown 8vo, limp cloth                                             2 00

*ATWOOD, Geo.--Practical Blow-Pipe Assaying.*

  12mo, cloth, illustrated                                          2 00

*AUCHINCLOSS, W. S.--Link and Valve Motions Simplified.*

  Illustrated with 37 wood-cuts and 21 lithographic plates, together
  with a Travel Scale and numerous useful tables. 8vo, cloth        3 00

*AXON, W. E. A.--The Mechanic's Friend.*

  A Collection of Receipts and Practical Suggestions Relating to
  Aquaria--Bronzing--Cements--Drawing--Dyes--Electricity--Gilding--
  Glass-working--Glues--Horology--Lacquers--Locomotives--Magnetism--
  Metal-working--Modelling--Photography--Pyrotechny--Railways--Solders--
  Steam-Engine--Telegraphy--Taxidermy--Varnishes--Waterproofing,
  and Miscellaneous Tools, Instruments, Machines, and Processes
  connected with the Chemical and Mechanic Arts. With numerous diagrams
  and wood-cuts. Fancy cloth                                        1 50

*BACON, F. W.--A Treatise on the Richards Steam-Engine Indicator, with
    directions for its use.*

  By Charles T. Porter. Revised, with notes and large additions as
  developed by American practice; with an appendix containing useful
  formulæ and rules for engineers. Illustrated. Fourth edition. 12mo,
  cloth                                                             1 00

*BARBA, J.--The Use of Steel for Constructive Purposes;*

  Method of Working, Applying, and Testing Plates and Brass. With a
  Preface by A. L. Holley, C.E. 12mo, cloth                         1 50

*BARNARD, Maj.-Gen. J. G.--The "C. S. A." and the Battle of Bull Run.*

  8vo, cloth                                                        1 25

---- *The Peninsular Campaign and its Antecedents,*

  As developed by the Report of Maj.-Gen. Geo. B. McClellan and other
  published Documents. 8vo, cloth                                   1 00
  12mo, paper                                                         30

---- *Notes on Sea-Coast Defence.*

  Consisting of Sea-Coast Fortification; the Fifteen-Inch Gun; and
  Casemate Embrasure. With an engraved plate of the Fifteen-Inch Gun.
  8vo, cloth                                                        2 00

*BARNARD, Maj.-Gen. J. G., and BARRY, Maj.-Gen. W. F.--Report of the
    Engineer and Artillery Operations of the Army of the Potomac,*

  From its Organization to the Close of the Peninsular Campaign.
  Illustrated by 18 maps, plans, etc. 8vo, cloth                    2 50

*BARNES, Lieut.-Com. JOHN S.--Submarine Warfare, Defensive and
    Offensive.*

  Comprising a full and complete History of the invention of the
  Torpedo, its employment in War, and results of its use. Descriptions
  of the various forms of Torpedoes, Submarine Batteries, and Torpedo
  Boats actually used in War. With 20 lithographic plates and many
  wood-cuts, 8vo, cloth                                             5 00

*BARRE DUPARCQ, EDWARD DE LA.--Elements of Military Art and History.*

  Translated by Col. Geo. W. Cullum, U.S.E. 8vo, cloth              3 50

*BARRETT, Capt. EDWARD.--Dead Reckoning; or, Day's Work.*

  8vo, flexible cloth                                               1 25

---- *Gunnery Instructions.*

  12mo, cloth                                                       1 25

*BEILSTEIN, F.-An Introduction to Qualitative Chemical Analysis.*

  Translated by I. J. Osbun. 12mo, cloth                              75

*BENET, Gen. S. V.--Electro-Ballistic Machines,*

  And the Schultz Chronoscope. Second edition. Illustrated. 4to, cloth
                                                                    3 00

---- *Military Law and Courts-Martial.*

  A Treatise on Military Law and the Practice of Courts-Martial. Sixth
  edition, revised and enlarged. 8vo, law sheep                     4 00

*BENTON, Col. J. G.--Ordnance and Gunnery.*

  A Course of Instruction in Ordnance and Gunnery. Compiled for the use
  of the Cadets of the U. S. Military Academy. Illustrated. Fourth
  edition, revised and enlarged. 8vo, cloth                         5 00

*BERRIMAN, Maj. M. W--The Militiaman's Manual and Sword-Play without a
    Master.*

  Rapier and Broad-Sword Exercises, copiously explained and illustrated;
  Small-Arm Light Infantry Drill of the United States Army; Infantry
  Manual of Percussion Musket; Company Drill of the United States
  Cavalry. Fourth edition. 12mo, cloth                              1 00

*BLAKE, W. P.--Report upon the Precious Metals;*

  Being Statistical Notices of the principal Gold and Silver producing
  regions of the World, represented at the Paris Universal Exposition.
  8vo, cloth                                                        2 00

---- *Ceramic Art.*

  A Report on Pottery, Porcelain, Tiles, Terra-Cotta, and Brick. 8vo,
  cloth                                                             2 00

*BOW, R. H.--A Treatise on Bracing,*

  With its application to Bridges and other Structures of Wood or Iron.
  156 illustrations. 8vo, cloth                                     1 50

*BOWSER, Prof. E. A.--An Elementary Treatise on Analytic Geometry.*

  Embracing Plain Geometry, and an Introduction to Geometry of three
  Dimensions. 12mo, cloth                                           1 75

---- *An Elementary Treatise on the Differential and Integral Calculus.*

  With numerous examples. 12mo, cloth                               2 25

*BOYNTON, Maj. EDWARD C.--History of West Point,*

  And its Military Importance during the American Revolution; and the
  Origin and Progress of the U. S. Military Academy. With 36 maps and
  engravings. Second edition. 8vo, fancy cloth                      3 50

*BRANDT, J. D.--Gunnery Catechism.*

  As applied to the service of the Naval Ordnance. Adapted to the latest
  Official Regulations, and approved by the Bureau of Ordnance, Navy
  Department. Revised edition. Illustrated. 18mo, cloth             1 50

*BREWERTON, G. D.--The Automaton Battery; or, Artillerist's Practical
    Instructor.*

  For all Mounted Artillery Manoeuvres in the Field. In box       1 00
  When sent by mail                                                 1 30

---- *The Automaton Regiment; or, Infantry Soldier's Practical
    Instructor.*

  For all Regimental Movements in the Field. In box                 1 00
  When sent by mail                                                 1 33

---- *The Automaton Company; or, Infantry Soldier's Practical
    Instructor.*

  For all Company Movements in the Field. In box                    1 25
  When sent by mail                                                 1 94

*BRINKERHOFF, Capt. R.--The Volunteer Quartermaster.*

  12mo, cloth                                                       1 00

*BUCKNER, Lieut. W. P.--Calculated Tables of Ranges for Navy and Army
    Guns.*

  8vo, cloth                                                        1 50

*BURGH, N. P.--Modern Marine Engineering,*

  Applied to Paddle and Screw Propulsion. Consisting of 36 colored
  plates, 259 practical wood-cut illustrations, and 403 pages of
  descriptive matter, the whole being an exposition of the present
  practice of James Watt & Co., J. & G. Rennie, R. Napier & Sons, and
  other celebrated firms. Thick 4to vol., cloth                    10 00
  Half morocco                                                     15 00

*BURT, W. A.--Key to the Solar Compass, and Surveyor's Companion.*

  Comprising all the rules necessary for use in the field; also
  description of the Linear Surveys and Public Land System of the United
  States, Notes on the Barometer, suggestions for an outfit for a survey
  of four months, etc. Fifth edition. Pocket-book form, tuck        2 50

*BUTLER, Capt. JOHN S.--Projectiles and Rifled Cannon.*

  A Critical Discussion of the Principal Systems of Rifling and
  Projectiles, with practical suggestions for their improvement, as
  embraced in a report to the Chief of Ordnance, U. S. Army. 4to, 36
  plates, cloth                                                     6 00

*CAIN, Prof. WM.--A Practical Treatise on Voussoir and Solid and Braced
    Arches.*

  16mo, cloth extra                                                 1 75

*CALDWELL, Prof. GEO. C., and BRENEMAN, Prof. A. A.--Manual of
    Introductory Chemical Practice.*

  For the use of Students in Colleges and Normal and High Schools. Third
  edition revised and corrected. 8vo, cloth, illustrated. New and
  enlarged edition                                                  1 50

*CAMPIN, FRANCIS.--On the Construction of Iron Roofs.*

  8vo, with plates, cloth                                           2 00

*CASEY, Brig.-Gen. SILAS--U. S. Infantry Tactics.*

  Vol. I.--School of the Soldier; School of the Company; Instruction for
  Skirmishers. Vol. II.--School of the Battalion, Vol. III.--Evolutions
  of a Brigade; Evolutions of a Corps d'Armée. Lithographed plates. 3
  vols. 24mo, cloth                                                 1 50

*CHAUVENET, Prof. W.--New Method of Correcting Lunar Distances, and
    Improved Method of Finding the Error and Rate of a Chronometer, by
    Equal Altitudes.*

  8vo, cloth                                                        2 00

*CHURCH, JOHN A.--Notes of a Metallurgical Journey in Europe.*

  8vo, cloth                                                        2 00

*CLARK, D. KINNEAR, C.E.--Fuel,*

  Its Combustion and Economy; consisting of Abridgments of Treatise on
  the Combustion of Coal and the Prevention of Smoke, by C. W. Williams;
  and the Economy of Fuel, by T. S. Prideaux. With extensive additions
  on recent practice in the Combustion and Economy of Fuel: Coal, Coke,
  Wood, Peat, Petroleum, etc. 12mo, cloth                           1 50

---- *A Manual of Rules, Tables, and Data for Mechanical Engineers.*

  Based on the most recent investigations. Illustrated with numerous
  diagrams. 1,012 pages. 8vo, cloth                                 7 50
  Half morocco                                                     10 00

*CLARK, Lt. LEWIS, U. S. N.--Theoretical Navigation and Nautical
    Astronomy.*

  Illustrated with 41 wood-cuts. 8vo, cloth                         1 50

*CLARKE, T. C.--Description of the Iron Railway Bridge over the
    Mississippi River at Quincy, Illinois.*

  Illustrated with 21 lithographed plans. 4to, cloth                7 50

*CLEVENGER, S. R.--A Treatise on the Method of Government Surveying,*

  As prescribed by the U. S. Congress and Commissioner of the General
  Land Office, with complete Mathematical, Astronomical, and Practical
  Instructions for the use of the United States Surveyors in the field.
  16mo, morocco                                                     2 50

*COFFIN, Prof. J. H. C.--Navigation and Nautical Astronomy.*

  Prepared for the use of the U. S. Naval Academy. Sixth edition. 52
  wood-cut illustrations. 12mo, cloth                               3 50

*COLBURN, ZERAH.--The Gas-Works of London.*

  12mo, boards                                                        60

*COLLINS, JAS. E.--The Private Book of Useful Alloys and Memoranda for
    Goldsmiths, Jewellers, etc.*

  18mo, cloth                                                         50

*COOKE, Brig.-Gen. PHILIP. ST. GEORGE.--New Cavalry Tactics.*

  16mo, morocco                                                     2 00

---- *Cavalry Practice.*

  Regulations for the movements of the Cavalry of the Army. 12mo.   1 00

*CORNWALL, Prof. H. B.--Manual of Blow-Pipe Analysis, Qualitative and
    Quantitative.*

  With a Complete System of Descriptive Mineralogy. 8vo, cloth, with
  many illustrations                                                2 50

*CRAIG, B. F.--Weights and Measures.*

  An account of the Decimal System, with Tables of Conversion for
  Commercial and Scientific Uses. Square 32mo, limp cloth             50

*CRAIG, Prof. THOS.--Elements of the Mathematical Theory of Fluid
    Motion.*

  16mo, cloth                                                       1 25

*CRAIGHILL, WM. P.--The Army Officer's Companion.*

  Principally designed for Staff Officers in the Field. Partly
  translated from the French of M. de Rouvre, Lieut.-Col. of the French
  Staff Corps, with additions from Standard American, French, and
  English authorities. 18mo, full roan                              1 50

*CULLUM, Col. GEORGE W.--Military Bridges.*

  Systems of Military Bridges in use by the U. S. Army; those adopted by
  the Great European Powers; and such as are employed in British India.
  With Directions for the Preservation, Destruction, and
  Re-establishment of Bridges. With 7 folding plates. 8vo, cloth    3 50

*DAVIS, C. B., and RAE, F. B.--Hand-Book of Electrical Diagrams and
    Connections.*

  Illustrated with 32 full-page illustrations. Second edition. Oblong
  8vo, cloth extra                                                  2 00

*DIEDRICH, JOHN.--The Theory of Strains.*

  A Compendium for the Calculation and Construction of Bridges, Roofs,
  and Cranes. Illustrated by numerous plates and diagrams. 8vo, cloth
                                                                    5 00

*DIXON, D. B.--The Machinist's and Steam-Engineer's Practical
    Calculator.*

  A Compilation of Useful Rules, and Problems Arithmetically Solved,
  together with General Information applicable to Shop-Tools,
  Mill-Gearing, Pulleys and Shafts, Steam-Boilers and Engines. Embracing
  Valuable Tables, and Instruction in Screw-cutting, Valve and Link
  Motion, etc. 16mo, full morocco, pocket form                      2 00

*DODD, GEO.--Dictionary of Manufactures, Mining, Machinery, and the
    Industrial Arts.*

  12mo, cloth                                                       1 50

*DOUGLASS, Prof. S. H., and PRESCOTT, Prof. A. B.--Qualitative Chemical
    Analysis.*

  A Guide in the Practical Study of Chemistry, and in the Work of
  Analysis. Fourth edition. 8vo, cloth                              3 50

*DUANE, Gen. J. C.--Manual for Engineering Troops.*

  Consisting of--Part I. Ponton Drill; II. Practical Operations of a
  Siege; III. School of the Sap; IV. Military Mining; V. Construction of
  Batteries. With 16 plates and numerous wood-cut illustrations. 12mo,
  half morocco                                                      1 50

*DUBOIS, A. J.--The New Method of Graphical Statics.*

  With 60 illustrations. 8vo, cloth                                 1 50

*DUFOUR, Gen. G. H.--The Principles of Strategy and Grand Tactics.*

  Translated from the French, by William P. Craighill, U. S. Engineers,
  from the last French edition. Illustrated. 12mo, cloth            1 50

*DURYEA, Col. A.--Standing Orders of the Seventh Regiment National
    Guards.*

  New edition. 16mo, cloth                                            50

*EASSIE, P. B.--Wood and its Uses.*

  A Hand-Book for the use of Contractors, Builders, Architects,
  Engineers, and Timber Merchants. Upwards of 250 illustrations. 8vo,
  cloth                                                             1 50

*EDDY, Prof. H. T.--Researches in Graphical Statics.*

  Embracing New Constructions in Graphical Statics, a New General Method
  in Graphical Statics, and the Theory of Internal Stress in Graphical
  Statics. 8vo, cloth                                               1 50

*ELIOT, Prof. C. W., and STORER, Prof. F. H.--A Compendious Manual of
    Qualitative Chemical Analysis.*

  Revised with the co-operation of the authors. By Prof. William R.
  Nichols. Illustrated. 12mo, cloth                                 1 50

*ELLIOT, Maj. GEO. H., U. S. E--European Light-House Systems.*

  Being a Report of a Tour of Inspection made in 1873. 51 engravings and
  21 wood-cuts. 8vo, cloth                                          5 00

*ENGINEERING FACTS AND FIGURES.*

  An Annual Register of Progress in Mechanical Engineering and
  Construction for the years 1863-64-65-66-67-68. Fully illustrated 6
  vols. 18mo, cloth (each volume sold separately), per vol:         2 50

*FANNING, J. T.--A Practical Treatise on Water-Supply Engineering.*

  Relating to the Hydrology, Hydrodynamics, and Practical Construction
  of Water-Works in North America. Third edition. With numerous tables
  and 180 illustrations. 650 pages. 8vo, cloth                      5 00

*FISKE, Lieut. BRADLEY A., U. S. N.--Electricity in Theory and Practice;
    or, The Elements of Electrical Engineering.*

  8vo, cloth                                                        2 50

*FOSTER, Gen. J. G., U. S. A.--Submarine Blasting in Boston Harbor,
    Massachusetts.*

  Removal of Tower and Corwin Rocks. Illustrated with seven plates. 4to,
  cloth                                                             3 50

*FOYE, Prof. J. C.--Chemical Problems.*

  With brief Statements of the Principles involved. Second edition,
  revised and enlarged. 16mo, boards                                  50

*FRANCIS, JAS. B., C. E.--Lowell Hydraulic Experiments:*

  Being a selection from Experiments on Hydraulic Motors, on the Flow of
  Water over Weirs, in Open Canals of Uniform Rectangular Section, and
  through submerged Orifices and diverging Tubes. Made at Lowell,
  Massachusetts. Fourth edition, revised and enlarged, with many new
  experiments, and illustrated with twenty-three copperplate engravings.
  4to, cloth                                                       15 00

*FREE-HAND DRAWING.*

  A Guide to Ornamental Figure and Landscape Drawing. By an Art Student.
  18mo, boards                                                      0 50

*FRY, Brig.-Gen. JAMES B.--Army Sacrifices; or, Briefs from Official
    Pigeon-Holes.*

  Sketches based on Official Reports, grouped together for the purpose
  of illustrating the Services of the Regular Army of the United States
  on the Indian Frontier. 16mo.                                     1 25

---- *History of Brevet Rank.*

  The History and Legal Effects of Brevets in the Armies of Great
  Britain and the United States, from the origin in 1692 until the
  present time. Crown 8vo, extra cloth                              3 00

*GILLMORE, Gen. Q. A.--Treatise on Limes, Hydraulic Cements, and
    Mortars.*

  Papers on Practical Engineering, U. S. Engineer Department, No. 9,
  containing Reports of numerous Experiments conducted in New York City
  during the years 1858 to 1861, inclusive. With numerous illustrations.
  8vo, cloth                                                        4 00

---- *Practical Treatise on the Construction of Roads, Streets, and
    Pavements.*

  With 70 illustrations. 12mo, cloth                                2 00

---- *Report on Strength of the Building-Stones in the United States,
    etc.*

  8vo, illustrated, cloth                                           1 50

---- *Coignet Beton and other Artificial Stone.*

  9 plates, views, etc. 8vo, cloth                                  2 50

---- *Fort Sumter.*

  Official Report of Operations against the Defences of Charleston
  Harbor, 1863. Comprising the descent upon Morris Island, the
  Demolition of Fort Sumter, and the siege and reduction of Forts Wagner
  and Gregg. With 76 lithographic plates, views, maps, etc. 8vo, cloth
                                                                    7 50
  Half Russia                                                      12 00

---- *Supplementary Report on Fort Sumter.*

  Supplementary Report to the Engineer and Artillery Operations against
  the Defences of Charleston Harbor in 1863. With 7 lithographed maps
  and views. 8vo, cloth                                             3 50

---- *Siege and Reduction of Fort Pulaski, Georgia.*

  Illustrated by maps and views. 8vo, cloth                         2 50

*GOODEVE, T. M.--A Text-Book on the Steam-Engine.*

  143 illustrations. 12mo, cloth                                    2 00

*GORDON, J. E. H.--Four Lectures on Static Induction.*

  12mo, cloth                                                         80

*GRAFTON, Capt. HENRY D.--A Treatise on the Camp and March.*

  With which is connected the Construction of Field-Works and Military
  Bridges. 12mo, cloth                                               75

*GREENER, WM., R. C. E.--A Treatise on Rifles, Cannon, and Sporting
    Arms.*

  8vo, cloth                                                        4 00
  Full calf                                                         6 00

*GRUNER, M. L.--The Manufacture of Steel.*

  Translated from the French, by Lenox Smith, with an appendix on the
  Bessemer process in the United States, by the translator. Illustrated.
  8vo, cloth                                                        3 50

*GUIDE TO WEST POINT and the U. S. Military Academy.*

  With maps and engravings. 18mo, flexible cloth                    1 00

*HALF-HOURS WITH MODERN SCIENTISTS.--Lectures and Essays,*

  By Professors Huxley, Barker, Stirling, Cope, Tyndall, Wallace,
  Roscoe, Huggins, Lockyer, Young, Mayer, and Reed. Being the University
  Series bound up. With a general introduction by Noah Porter, President
  of Yale College. 2 vols. 12mo, cloth, illustrated                 2 50

*HAMERSLY, LEWIS B.--The Records of Living Officers of the U. S. Navy
    and Marine Corps.*

  Compiled from Official Sources. Third edition. Cloth, 8vo.        2 50

*HAMILTON, W. G.--Useful Information for Railway Men.*

  Sixth edition, revised and enlarged. 562 pages, pocket form. Morocco,
  gilt                                                              2 00

*HARRISON, Col. WALTER.--Pickett's Men.*

  A Fragment of War History. With portrait of Gen. Pickett. 12mo, cloth
                                                                    1 25

*HARRISON, W. B.--The Mechanic's Tool Book,*

  With Practical Rules and Suggestions for Use of Machinists,
  Iron-Workers, and others. Illustrated with 44 engravings. 12mo, cloth
                                                                    1 50

*HARWOOD, A. A.--Naval Courts-Martial.*

  Law and Practice of United States Naval Courts-Martial. Adopted as a
  Text-Book at the U. S. Naval Academy. 8vo, law-sheep              3 00

*HASKINS, C. H.--The Galvanometer and its Uses.*

  A Manual for Electricians and Students. Second edition. 12mo, morocco
                                                                    1 50

*HAUPT, Brig.-Gen. HERMAN.--Military Bridges.*

  For the Passage of Infantry, Artillery, and Baggage-Trains; with
  suggestions of many new expedients and constructions for crossing
  streams and chasms. Including also designs for Trestle and Truss
  Bridges for Military Railroads, adapted specially to the wants of the
  Service of the United States. Illustrated by 69 lithographic
  engravings. 8vo, cloth                                            6 50

*HEAD, Capt. GEORGE E.--A New System of Fortifications.*

  Illustrated. 4to, paper                                             50

*HEAVY ARTILLERY TACTICS: 1863.*

  Instructions for Heavy Artillery; prepared by a Board of Officers, for
  the use of the Army of the United States. With service of a gun
  mounted on an iron carriage, and 39 plates. 12mo, cloth           1 00

*HENRICI, OLAUS.--Skeleton Structures, especially in their application
    to the Building of Steel and Iron Bridges.*

  With folding plates and diagrams. 8vo, cloth                      1 50

*HENRY, GUY V.--Military Record of Civilian Appointments in the United
    States Army.*

  2 vols. 8vo, cloth                                               10 00

*HETH, Capt. HENRY.--System of Target Practice.*

  For the Use of Troops when armed with the Musket, Rifle-Musket, Rifle,
  or Carbine. Prepared principally from the French. 18mo, cloth       50

*HEWSON, WM.--Principles and Practice of Embanking Lands from River
    Floods, as applied to the Levees of the Mississippi.*

  8vo, cloth                                                        2 00

*HOLLEY, ALEXANDER L.--A Treatise on Ordnance and Armor.*

  Embracing descriptions, discussions, and professional opinions
  concerning the materials, fabrication, requirements, capabilities, and
  endurance of European and American Guns, for Naval, Sea-Coast, and
  Iron-Clad Warfare, and their Rifling, Projectiles, and Breech-Loading;
  also, results of experiments against armor, from official records,
  with an appendix referring to Gun-Cotton, Hooped Guns, etc., etc. 948
  pages, 493 engravings, and 147 Tables of Results, etc. 8vo, half roan
                                                                    7 50
  Half Russia                                                      10 00

---- *Railway Practice.*

  American and European Railway Practice in the economical Generation of
  Steam, including the Materials and Construction of Coal-burning
  Boilers, Combustion, the Variable Blast, Vaporization, Circulation,
  Superheating, Supplying and Heating Feed-water, etc., and the
  Adaptation of Wood and Coke-burning Engines to Coal-burning; and in
  Permanent Way, including Road-bed, Sleepers, Rails, Joint-fastenings,
  Street Railways, etc., etc. With 77 lithographed plates. Folio, cloth
                                                                   12 00

*HOTCHKISS, JED., and ALLAN, WILLIAM.--The Battle-Fields of Virginia.*

  Chancellorsville, embracing the Operations of the Army of Northern
  Virginia, from the First Battle of Fredericksburg to the Death of
  Lt.-Gen. T. J. Jackson. Illustrated with five maps and portrait of
  Stonewall Jackson. 8vo, cloth                                     3 50

*HOWARD, C. R.--Earthwork Mensuration on the Basis of the Prismoidal
    Formulæ.*

  Containing simple and labor-saving method of obtaining Prismoidal
  Contents directly from End Areas. Illustrated by Examples, and
  accompanied by Plain Rules for Practical Uses. Illustrated. 8vo,
  cloth                                                             1 50

*HUNTER, Capt. R. F.--Manual for Quartermasters and Commissaries.*

  Containing Instructions in the Preparation of Vouchers, Abstracts,
  Returns, etc. 12mo, cloth                                         1 00
  Flexible morocco                                                  1 50

*INDUCTION-COILS.--How Made and How Used.*

  63 illustrations. 16mo, boards                                      50

*INSTRUCTIONS FOR FIELD ARTILLERY.*

  Prepared by a Board of Artillery Officers. To which is added the
  "Evolutions of Batteries." Translated from the French by Brig.-Gen. R.
  Anderson, U. S. A. 122 plates. 12mo, cloth                        1 00

*ISHERWOOD, B. F.--Engineering Precedents for Steam Machinery.*

  Arranged in the most practical and useful manner for Engineers. With
  illustrations. Two volumes in one. 8vo, cloth                     2 50

*IVES, Lieut. R. A.--Military Law.*

  A Treatise on Military Law, and the Jurisdiction, Constitution, and
  Procedure of Military Courts. With a Summary of the Rules of Evidence
  as applicable to such Courts. 400 pages. 8vo, law-sheep           4 00

*JANNETTAZ, EDWARD--A Guide to the Determination of Rocks:*

  Being an Introduction to Lithology. Translated from the French by G.
  W. Plympton, Professor of Physical Science at Brooklyn Polytechnic
  Institute. 12mo, cloth                                            1 50

*JEFFERS, Capt. W. N., U. S. N.--Nautical Surveying.*

  Illustrated with 9 copperplates and 31 wood-cut illustrations. 8vo,
  cloth                                                             5 00

*JOMINI, Gen. BARON DE.--Campaign of Waterloo.*

  The Political and Military History of the Campaign of Waterloo.
  Translated from the French by Gen. S. V. Benét. Third edition. 12mo,
  cloth                                                             1 25

---- *Treatise on Grand Military Operations.*

  Illustrated by a Critical and Military History of the Wars of
  Frederick the Great. With a Summary of the Most Important Principles
  of the Art of War. Illustrated by maps and plans. Translated from the
  French by Col. S. B. Holabird, U. S. A. 2 vols. 8vo and Atlas. Cloth
                                                                   15 00
  Half calf or morocco                                             21 00
  Half Russia                                                      22 50

*JONES, H. CHAPMAN.--Text-Book of Experimental Organic Chemistry for
    Students.*

  18mo, cloth                                                       1 00

*JOYNSON, F. H.--The Metals used in Construction: Iron, Steel, Bessemer
    Metal, etc., etc.*

  Illustrated. 12mo, cloth                                            75

---- *Designing and Construction of Machine Gearing.*

  Illustrated. 8vo, cloth                                           2 00

*KANSAS CITY BRIDGE, THE.*

  With an account of the Regimen of the Missouri River, and a
  description of the methods used for Founding in that River. By O.
  Chanute, Chief-Engineer, and George Morrison, Assistant-Engineer.
  Illustrated with five lithographic views and twelve plates of plans.
  4to, cloth                                                        6 00

*KELTON, Gen. J. C.--New Bayonet Exercise.*

  A New Manual of the Bayonet, for the Army and Militia of the United
  States. With 40 beautifully engraved plates. Fifth edition. Revised.
  12mo, cloth                                                       2 00

*KING, W. H.--Lessons and Practical Notes on Steam,*

  The Steam-Engine, Propellers, etc., etc., for young Marine Engineers,
  Students, and others. Revised by Chief-Engineer J. W. King, U. S.
  Navy. Nineteenth edition, enlarged. 8vo, cloth                    2 00

*KIRKWOOD, JAS. P.--Report on the Filtration of River Waters for the
    supply of Cities,*

  As practised in Europe, made to the Board of Water Commissioners of
  the City of St. Louis. Illustrated by 30 double-plate engravings. 4to,
  cloth                                                            15 00

*LARRABEE, C. S.--Cipher and Secret Letter and Telegraphic Code, with
    Hogg's Improvements.*

  The most perfect secret code ever invented or discovered. Impossible
  to read without the key. 18mo, cloth                              1 00

*LAZELLE, Capt. H. M., U. S. A.--One Law in Nature.*

  A New Corpuscular Theory, comprehending Unity of Force, Identity of
  Matter and its Multiple Atom Constitution; applied to the Physical
  Affections, or Modes of Energy. 12mo.                             1 50

*LECOMTE, FERDINAND.--The War in the United States.*

  A Report to the Swiss Military Department. Translated from the French
  by a Staff Officer. 12mo, cloth                                     75

*LE GAL, Col. EUGENE.--School of the Guides.*

  Designed for the use of the Militia of the United States. 16mo, cloth
                                                                      60

*LENDY, Capt.--Maxims and Instructions on the Art of War.*

  A Practical Military Guide for the use of Soldiers of all Arms and of
  all Countries. Translated from the French. 18mo, cloth              75

*LEVY, Com. U. P.--Manual of Internal Rules and Regulations for
    Men-of-War.*

  Third edition, revised and enlarged. 18mo, flexible cloth           30

*LIEBER, FRANCIS, LL.D.--Instructions for Armies.*

  Instructions for the Government of Armies of the United States in the
  Field. 12mo, paper                                                  25

*LIPPITT.--Special Operations of War.* 12mo, cloth                  1 00

---- *Field Service in War.* 12mo, cloth                            1 00

---- *Tactical Use of the Three Arms.* 12mo, cloth                  1 00

---- *Intrenchments.* 12mo, cloth                                   1 25

*LOCK, C. G., WIGNER, G. W., and HARLAND, R. H.--Sugar Growing and
    Refining.*

  Treatise on the Culture of Sugar-Yielding Plants, and the Manufacture
  and Refining of Cane, Beet, and other sugars. 8vo, cloth, illustrated
                                                                   12 00

*LOCKWOOD, THOS. D.--Electricity, Magnetism, and Electro-Telegraphy.*

  A Practical Guide for Students, Operators, and Inspectors. 8vo, cloth

*LORING, A. E.--A Hand-Book on the Electro-Magnetic Telegraph.*

  Paper boards                                                      0 50
  cloth                                                               75
  Morocco                                                           1 00

*LUCE, Capt. S. B.--Seamanship.*

  For the use of the United States Naval Academy. Fourth edition. Crown
  8vo, revised and improved, illustrated by 89 full-page copperplate
  engravings, half roan                                             7 50

  --> Text-Book at the U. S. Naval Academy, Annapolis.

---- *Naval Light Artillery.*

  By Lieut. W. H. Parker, U. S. N. Third edition, revised by Capt. S. B.
  Luce, Assistant Instructor of Gunnery and Tactics at the U. S. Naval
  Academy. 22 plates. 8vo, cloth                                    3 00

*MacCORD, Prof. C. W.--A Practical Treatise on the Slide-Valve by
    Eccentrics,*

  Examining by methods the action of the Eccentric upon the Slide-Valve,
  and explaining the practical processes of laying out the movements,
  adapting the valve for its various duties in the steam-engine. Second
  edition. Illustrated. 4to, cloth                                  2 50

*McCLELLAN, Gen. GEO. B.--Report of the Army of the Potomac,*

  Of its operations while under his command. With maps and plans. 8vo,
  cloth                                                             1 00
  Paper                                                               50

*McCULLOCH, Prof. R. S.--Elementary Treatise on the Mechanical Theory of
    Heat, and its application to Air and Steam Engines.*

  8vo, cloth                                                        3 50

*MANUAL OF BOAT EXERCISE.*

  At the U. S. Naval Academy, designed for the practical instruction of
  the Senior Class in Naval Tactics. 18mo, flexible cloth             50

*MENDELL, G. H.--Military Surveying.*

  A Treatise on Military Surveying, Theoretical and Practical, including
  a description of Surveying Instruments. With 70 wood-cut
  illustrations. 12mo, cloth                                        1 50

*MERRILL, Col. WM. E., U. S. A.--Iron Truss Bridges for Railroads.*

  The method of calculating strains in Trusses, with a careful
  comparison of the most prominent Trusses, in reference to economy in
  combination, etc., etc. Illustrated. 4to, cloth                   5 00

*MICHAELIS, Capt. O. E.--The Le Boulenge Chronograph.*

  With three lithographed folding plates of illustrations. 4to,
  illustrated, cloth                                                3 00

*MICHIE, Prof. P. S.--Elements of Wave Motion relating to Sound and
    Light.*

  Text-Book for the U. S. Military Academy. 8vo, cloth, illustrated
                                                                    5 00

*MINIFIE, WM--Mechanical Drawing.*

  A Text-Book of Geometrical Drawing for the use of Mechanics and
  Schools, in which the Definitions and Rules of Geometry are familiarly
  explained; the Practical Problems are arranged, from the most simple
  to the more complex, and in their description technicalities are
  avoided as much as possible. With illustrations for Drawing Plans,
  Sections, and Elevations of Railways and Machinery; an Introduction to
  Isometrical Drawing, and an Essay on Linear Perspective and Shadows.
  Illustrated with over 200 diagrams engraved on steel. Ninth edition.
  With an Appendix on the Theory and Application of Colors. 8vo, cloth
                                                                    4 00

  "It is the best work on drawing that we have ever seen, and is
  especially a text-book of Geometrical Drawing for the use of Mechanics
  and Schools. No young Mechanic, such as a Machinist, Engineer,
  Cabinet-maker, Millwright, or Carpenter, should be without
  it."--_Scientific American._


---- *Geometrical Drawing.*

  Abridged from the octavo edition, for the use of schools. Illustrated
  with 48 steel plates. Fifth edition. 12mo, cloth                  2 00

*MODERN METEOROLOGY.*

  A Series of Six Lectures, delivered under the auspices of the
  Meteorological Society in 1878. Illustrated. 12mo, cloth          1 50

*MONROE, Col. J.--Light Infantry Company and Skirmish Drill.*

  Bayonet Fencing; with a Supplement on the Handling and Service of
  Light Infantry. 32mo, cloth                                         75

*MOORE, FRANK--The Rebellion Record.*

  Containing a full and concise Diary of Events from December, 1860, to
  the close of the War of the Rebellion, with Official Reports of State
  Officers and Narratives of all the Battles and Skirmishes that
  occurred. Complete in twelve volumes royal 8vo. Illustrated with 158
  steel engraved Portraits of distinguished Generals and Prominent Men,
  together with numerous Maps and Plans of Battles. Price in cloth
                                                                   60 00
  Library sheep                                                    72 00
  Half calf, antique                                               78 00
  Half morocco                                                     78 00
  Half Russia                                                      84 00

---- *Portrait Gallery of the War, Civil, Military, and Naval.*

  A Biographical Record. Illustrated with 60 fine portraits on steel. 1
  vol. 8vo, cloth                                                   6 00
  Half calf                                                         7 50

*MORRIS, E.--Easy Rules for the Measurement of Earthworks, by Means of
    the Prismoidal Formula.*

  78 illustrations. 8vo, cloth                                      1 50

*MORRIS, Gen. WM. H.--Field Tactics for Infantry.*

  Illustrated. 18mo, cloth                                            75

---- *Infantry Tactics.*

  2 vols. 24mo.                                                     2 00
  2 vols. in one, cloth                                             1 50




Transcriber's Notes:

The following corrections which did not concern obvious printer's errors
have been made to the text.

  -In the Table of Content, the formatting of the entry for "Dialysis"
   was changed in order to indicate that this part is a section of the
   chapter "Methods of Destruction of the Organic Substances"

  -"treated with "_mélaïnocome_"" was: "treated with "melaniocome""

  -The sentence "M. Salleron offers for sale a small apparatus
  (Fig. 20)" wrongly referred to Fig. 16.

  -"If the crystals originate from fresh blood, they appear as
   represented in Fig. 21; crystals from old blood are represented in
   Fig. 22." wrongly referred to Fig. 17 and 18; the same was the case
   in "The fluid is examined from time to time under the microscope:
   when it is sufficiently concentrated, crystals, presenting the
   appearance represented in Figs. 21 or 22, will be observed."

  -"an oxidizing body" was: "an oxydizing body"

  -"condenser" was: "condensor"

  -"areometer (alcoholmeter)" was: "areometer (alcoolmeter)"