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+*** START OF THE PROJECT GUTENBERG EBOOK 44048 ***
+
+  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,
+
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+
+
+
+*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
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+*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
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+  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,
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+*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
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+*BARNARD, Maj.-Gen. J. G.--The "C. S. A." and the Battle of Bull Run.*
+
+  8vo, cloth                                                        1 25
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+
+  As developed by the Report of Maj.-Gen. Geo. B. McClellan and other
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+---- *Notes on Sea-Coast Defence.*
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+  8vo, cloth                                                        2 00
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+*BARNARD, Maj.-Gen. J. G., and BARRY, Maj.-Gen. W. F.--Report of the
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+  Illustrated by 18 maps, plans, etc. 8vo, cloth                    2 50
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+*BARNES, Lieut.-Com. JOHN S.--Submarine Warfare, Defensive and
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+
+  Comprising a full and complete History of the invention of the
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+  wood-cuts, 8vo, cloth                                             5 00
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+*BARRE DUPARCQ, EDWARD DE LA.--Elements of Military Art and History.*
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+  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
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+*BENET, Gen. S. V.--Electro-Ballistic Machines,*
+
+  And the Schultz Chronoscope. Second edition. Illustrated. 4to, cloth
+                                                                    3 00
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+---- *Military Law and Courts-Martial.*
+
+  A Treatise on Military Law and the Practice of Courts-Martial. Sixth
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+
+*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
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+*BERRIMAN, Maj. M. W--The Militiaman's Manual and Sword-Play without a
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+  Rapier and Broad-Sword Exercises, copiously explained and illustrated;
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+  Manual of Percussion Musket; Company Drill of the United States
+  Cavalry. Fourth edition. 12mo, cloth                              1 00
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+*BLAKE, W. P.--Report upon the Precious Metals;*
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+  Being Statistical Notices of the principal Gold and Silver producing
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+  8vo, cloth                                                        2 00
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+*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
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+*BOWSER, Prof. E. A.--An Elementary Treatise on Analytic Geometry.*
+
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+---- *An Elementary Treatise on the Differential and Integral Calculus.*
+
+  With numerous examples. 12mo, cloth                               2 25
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+*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.*
+
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+  Department. Revised edition. Illustrated. 18mo, cloth             1 50
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+*BREWERTON, G. D.--The Automaton Battery; or, Artillerist's Practical
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+*BRINKERHOFF, Capt. R.--The Volunteer Quartermaster.*
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+  12mo, cloth                                                       1 00
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+*BUCKNER, Lieut. W. P.--Calculated Tables of Ranges for Navy and Army
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+  8vo, cloth                                                        1 50
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+*BURGH, N. P.--Modern Marine Engineering,*
+
+  Applied to Paddle and Screw Propulsion. Consisting of 36 colored
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+*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)"
+
+
+
+
+
+End of the Project Gutenberg EBook of Legal Chemistry, by J. P. Battershall
+
+*** END OF THE PROJECT GUTENBERG EBOOK 44048 ***