qgW WOT a wffi BijWBWMw [^ tM p pietywM^fwiu. -j t i aajav'w.i w- "i -^i umv aM B WSWfl W t ' WW t 'w i 'W^i' i'* ' '^^ ite , ifi< > W wiai i . ) i-,'»r' i . - i ji [_' ^ The original of tliis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924031490059 arVl9343'^°"'*" ""'"^^^y Library •-.faal chemistn olm,anx ^^^4 031 490 o" J^EGAL (^HEMISTRY. A GUIDE DETECTION OF POISONS, EXAMINATION OF STAINS, ETC,, 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. BATTER8HALL, Nat. Sc. D. WITH' A PREFACE BY C. F. CHANDLER, Ph. D., M.D., LL.D. NEW YORK: D. VAN NOSTRAND, Publisher, 23 Murray Street and 27 Warren Street. t876. /t.n?^ Copyright. D. VAN NOSTRAND. 1876. UI^IVERSITYi 08RARY 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 considera- tions 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. C. 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 Marshes test 17 Marshes test 21 RaspaiVs test 29 Reinsch^s test 30 Detection of Antimony 30 Flandin and Danger's apparatus 32 Naquefs apparatus 34 Detection of Mercury 36 Smithson^ s pile 36 Flandin and Danger'' s apparatus 37 Detection of Phosphorus 39 Orpild's viethod. 39 Mistckerlich? 5 method 40 DusarVs method^ as modified by Blondlot 40 Presenilis and Neubauer" s method 42 Detection of Phosphorus by means of bisulphide of carbon 43 Detection of Phosphorous Acid 4^ Estimation of Phosphorus 45 Detection of Acids. 46 Hydrochloric Acid 46 Nitric " 47 2 CONTENTS. PAGE Detection of Poisons, {Continued). Sulphttric 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. 36 Detection of Metals 56 Detection of alkaloids and some ill-defined organic substances 65 Stasis method 65 " " as modified by Otto 69 " " " " Uslar and Erdman 70 Rodgers and Girdwood's method. . .-. 71 Prolliiis's method 72 Graham and Ho/man's method. 7^ Application of Dialysis in the detection of Alkaloids 7^. Identification of the Alkaloid. 7^ 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 g^. Miscellaneous Examinations 96 Determination of the nature and color of the hair and beard 96 Determijtaiion of the color of the hair and beard 96 Determination of the nature of the hair qg Examination of Fire-arms too The gun is provided with a flint-lock and -was charged with ordinary powder 100 The gun is not provided with a flint-lock 10^ 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 . no Falsification of coins and alloys 112 CONTENTS. 3 PAGE Miscellaneous Examinations, {Contimicd). Examination of alimentary and pharmaceutical substances 1 14 Flour aitd Bread. 114 Fixed Oils 12S a Olive Oil intended for table use 128 b Olive Oil intended for maiiufacturing J>ttrposes 130 c Colza Oil 130 d Hemp-seed Oil i 131 e..Linseed Oil , 131 Milk 131 Wine 136 Vinegar 141 Sulphate of Quinine 142 Examination of blood stains 144 Examination of spermatic stains 152 Appendix 157 Books on Toxicology, etc 1 62 Memoirs on Toxicology, etc 162 Index 175 LEGAL CHEMISTRY. The term Legal Chemistry is applied to that branch of the science which has for its office the solution of problems pro- posed 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 re- sorted 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 man- ipulation, 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 ques- tions that might arise. In addition to cases of supposed poi- soning, 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. 6 LEGAL CHEMISTRY. 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 ex- tended consideration than the limits of this work would per- mit. The several subjects will be treated as briefly as possible, and at the same time, so as to convey an exact idea of the meth- ods employed, leaving to the expert the selection of the particu- lar 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. Exanjinations of this class are extremely sim- ple, the analysis of the substances found, confined to a few char- acteristic reactions, being a matter of no great difficulty. We will not here dwell longer upon this subject, inasmuch as the an- alytical 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 INTRODUCTION. -j mixed with the organic substances encountered ia the stomach, or absorbed by, and intimately united with the tissues of the various organs is more difficult. If, however, other informa- tion, 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 speci- fied as to the nature of the poison used, the difiiculty 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 indi- vidual 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. IWETHODS OF DEJ^TRITCTION OF THE OROANIC SUBSTAIVCES. 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 DESTRUCTION OF THE ORGANIC SUBSTANCES. 9 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 T* 10 LEGAL CHEMISTRY. 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 com- pound, 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 exclu- sively in cases where the poisoning has been caused by ar- senic, for, if applied in other instances, a subsequent treat- ment would be necessary in order to redissolve the metal separated from its decomposed sulphate. BV 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, how- ever, to the imperfect admixture of the organic matter with the salt used for its decomposition, it was necessary to take a large excess cf 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 causftic potassa. DESTRUCTION OF THE ORGANIC SUBSTANCES. 1 1 and a quantity of water varying with the weight of the sub- stances 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 procelain 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 like- wise 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 appli- cation, 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 12 LEGAL CHEMISTRY. is too well aware of the difficulty of thoroughly washing a pre- cipitate, 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 lo 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 com- plicated than the simple treatment with nitrate of potassa, and possesses, moreover, no advantages over the latter process. DESTRUCTION OF THE ORGANIC SUBSTANCES. 13 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. yacquelain 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 14 LEGAL CHEMISTRY. 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 desir- able, and preseiits 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-olea- ginous substances is soon accomplished. The latter sub- stances 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 re- moved 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 Gaidtier de Claubry, in cases where the detection of arsenic is de- sired, to saturate and afterwards boil the suspected fluid with sulphuric acid, in order to remove the nitric and hydro- chloric acids present. DESTRUCTION OF THE ORGANIC SUBSTANCES. IS 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 col- loid bodies being retained above the membrane. The organic matter to be eliminated in toxicological researches being col- loids, and the poisons usually employed being crystalloids, the value of dialysis as a method of separation is evi- dent. The process is exe- cuted as follows : A wooden, — or better, a gutta-percha— cylinder (Fig.i), 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. Fig. i6 LEGAL CHEMISTRY. which, upon drying, shrinks and completely closes the aper- ture. If its continuity becomes impaired, the pores of the mem- brane 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°* — or, in dilute acids, if the presence of an alkaloidis 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 pre- viously 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 exam- ination is placed in a beil-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 contain- ing water. In other respects the opera- tion is performed in the same manner as with the apparatus represented in Fig. i. Fig. J. * 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 : II. DKTJBCTIOIV OF POISOIV8, THE PRESEIVCE OF WHICH IS SUSPECTED. DETECTION OF ARSEIVIC- It is frequently required, in chemical jurisprudence, to in- stitute a search for arsenic in the remains of a deceased per- son, 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 de- cisive reactions, determine its character. Three methods exist which permit of this result ; they are : I St. 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 ad- diton of pure potassa. The fluid is then filtered, an excess 1 8 LEGAL CHEMISTRY. 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, how- ever, 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,* and the solution so obtained subsequently evaporated to dry- ness 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 treat- ment into a mixture of sulphate and arsenate of potassa, the reaction being completed in about fifteen minutes. The mix- ture 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 ex- posed 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 pre- cipitation 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 sub- *The sulphur, usually accompanying the precipitate o£ sulphide of arsenic, is insoluble in ammonia. — Trans. DETECTION OF ARSENIC. 19 stances is, however, accomplished by means of chlorate o£ potassa and hydrochloric acid. To insure the complete pre- cipitation of the arsenic, it is advisable to conduct sulphur- Fig. 3. etted hydrogen through the solution, at a temperature of 700 for twelve hours, and then allow the fluid to remain in a 20 LEGAL CHEMISTRY. 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 reduc- tion 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 car- bonate of soda and cyanide of potassium. The ap- paratus employed is represented in Fig. 3 : a, is an ap- paratus producing a constant supply of carbonic acid. Upon opening Mohr's clamp, g, the gas passes into the flask /4, which contains sulphuric acid ; it is then conducted, by means of the tube «', into the reduction tube k, which has an interior diameter of 8 mm. This tube is represented, in half size, in Fig 4. The reduction is performed as follows : The ^ sulphide of arsenic is ground in a small mortar, pre- J» viously warmed, together with 12 parts of a mixture H consisting of 3 parts of carbonate of soda and i part I J of cyanide of potassium, both salts being perfectly \ ^ I dry. The powder thus obtained is placed upon a ^ ' piece of paper rolled in the form of a gutter, and in- a* troduced into the reduction tube. The latter is then , ' 1 turned half round its axis, so as to cause the mixture [I to fall in de without soiling the other parts of the * — tube. The paper is now withdrawn and the apparatus Fig. 4. mounted. Upon opening the clamp g, and strongly heating the mixture by either the flame of a gas or an alcohol DETECTION OF ARSENIC. 21 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 identifi- cation, 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 per- mits 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 correspond- ing 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 trans- formation 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 open- ings, 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 extrem- ity, the evolved gas, if ignited, burns with a pale non-luminous flame. The air should be completely expelled from the appar- atus 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 2 2 LEGAL CHEMISTRY. 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 arseni ous acid. In case a large amount of the poison is present, it can be recognized by the appearance of the flame, and by in- clining 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 : I St. At an elevated temperature it is decomposed into its two constituent elements. 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 lu- minous portion I, which sur- rounds the first. The maximum temperature exists in O at the point of union of the two parts of the flame. Owing to an in- Fig. 5. sufficient 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 sur- face 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 DETECTION OF ARSENIC. 23 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 ap- paratus the form represented in Fig. 6. A is the flask in Fig. 6, 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 ; * it passes through the sheet-iron furnace R, supported upon G. The screen D pro- tects the portion D £ oi the tube C from the heat. The gas disengaged is ignited at £ 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 * 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 pro- duced both on the exterior and interior of the tube. — Trans. 2 4 LEGAL CHEMISTRY. generating flask,* and the solution containing arsenious acid added : the evolution of gas commences immediately. The tube ^serves to retain any liquids that may be held suspend- ed. The gas then passes through the part C D ol 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 mir- ror-like ring. The small quantity of gas that escapes decom- position, 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 fol- lowing tests should be applied : 1. The color of the spots is distinctive : arsenical spots are brown and exhibit a metallic lustre, whereas those origina- ting 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 cur- rent 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 so- * The addition of a few drops of .solution of bichloride of platinum to the mixture of zinc, water and sulphuric acid is advisable. — Tram DETECTION OF ARSENIC. 25 lution 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 hydro- chloric acid. b. If the ring is dissolved in pure water and an am- moniacal 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 enu- merated 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 chlo- rine into solution of carbonate of soda), they are immediately dissolved ; if, on the other hand, they are produced by anti- mony, they remain unaltered by this treatment. Such are the properties exhibited by soluble compounds of arsenic when treated by Marsh's process ; the following pre- cautions are, however, necessary when this test is made use of in medico-legal examinations. 26 LEGAL CHEMISTRY. 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 indispen- sable even though, instead of the organs themselves, the con- tents of the alimentary canal are taken. In the latter instance, the solids are separated from the fluids present by filtra- tion, 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 ap- paratus by allowing the gas to evolve for some time, and the suspected fluid then introduced into the generating flask. Dan- ger of explosion would be incurred were the gas ignited when mixed with air.* * The effervescence of the mixture is prevented by sltnoly 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 dif- ferent parts. — Trans. DETECTION OF ARSENIC. 27 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 em- ployed do not originate from impurities present in the re- agents 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 differ- ent 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 there- fore 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 tox- icological 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 28 LEGAL CHEMISTRY. of sulphuric acid, by means of which the disengagement of gas is rendered more energetic* 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'), but into the solid arsenide of hydrogen (As* H^). This latter com- pound, upon which pure nascent hydrogen has no" effect, is transformed into gaseous arsenetted hydrogen by the simulta- neous action of nascent hydrogen and organic substances. These facts are of the greatest importance, for they might pos- sibly cause a loss of arsenic when it is present, as well as deter- mine 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 impossi- ble. The second case may also occur : if the zinc placed in the apparatus contains arsenic, and the sulphuric acid used con- tains nitrous compounds, the evolved gas will fail to exhibit any evidence of the presence of arsenic, owing to the forma- tion of the solid arsenide of hydrogen. Upon adding the sus- pected 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 so- lution under examination was originally free from this metal. * Owing to the impurities often occurring in zinc, the use of distilled magnesium in Marsh's apparatus has also been suggested. This metal is DETECTION OF ARSENIC. 29 RASPAILS 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 chlo- rine water added. If the plate is then allowed to stand for a moment and the substance under examination contains arse- nic, 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 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 in- solubility 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. 3° LEGAL CHEMLSTRY. it extracts the poison from but a very small portion of the solu- tion containing it : we have not, however, personally tested its merits.* DETECTIOW OF AWTIMOIVY. Strictly speaking the salts of antimony are more thera- peutic 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 * 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 boUing with hydrochloric acid, and the fluid filtered. Some pure copper gauze or foil, having a polished surface, is then immersed in the boiling solu- tion, 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 6S 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 effect- ing the detection of a very minute trace of the poison, — Trans. DETECTION OF ANTIMONY. 31 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 insti- tuted, 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. Tlie 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 : I. 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 or- ganic matter completed in the usual manner. The carbonaceous residue obtained is pulverized, and then boiled with a solution 32 LEGAL CHEMISTRY. of tartaric acid. By this treatment the antimonate of soda present is converted into a double tartrate of antimony and soda, whicli is easily soluble in water. The solution is filtered and theii 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 oper- ation. 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. This apparatus consists of a wide necked jar ^ (Fig- 7) for the generation of the gas, the mouth of which is closed with a cork having two openings. The safety tube .5, which is funnel-shaped at its upper extremity and has its lower end drawn out to a point, passes through one of these apertures : DETECTION OF ANTIMONY. 33 Fig. 7. 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 condensor C, 0.03 metre in diameter, and 0.25 metre in length. This terminates at its lower ex- tremity 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 Z>, o.oi 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 34 LEGAL CHEMISTRY. 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 conden- ses, and finally falls into the dish F. Both portions are subse- quently examined by means of reactions necessary to establish the presence of the acid. If the ignited gas contains antimo- netted 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 appar- atus, or otherwise examined for antimony. naquet's apparatus. 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 Fig. 8. DETECTION OF ANTIMONY. 35 in the tube D (Fig. 7), together with the intermediate oxide of antimony. The following method secures the complete separ- ation 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 hydro- gen causes a precipitation of metallic silver, all the arsenic re- maining in solution as arsenious acid ; the antimonetted hydrogen is decomposed into insoluble antimonate of silver. After the operation has continued for several hours, the appar- atus 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 preci- pitate 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 36 LEGAL CHEMISTRY. 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 con- ducted 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. DETXICXIOIV OF OTEKCITKY. 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 where- in 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 DETECTION OF MERCURY. 37 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 re- store to it its natural color. The danger of mistake arising from this fact is obviated by introducing the copper plate in- to 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 rub- bing them with a piece of gold foil when the latter will ac- quire 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 detec- tion of minute quantities rendered impossible. APPARATUS PROPOSED BY FLANDIN AND DANGER. This apparatus consists of a stand S, (Fig. 9) supporting a balloon A, which serves as the reservoir of the suspected solu- tion, 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. 38 LEGAL CHEMISTRY. 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, in- serted 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 sub- merged at first ; soon, however, it be- comes uncovered, owing to the depres- sion 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 disengage- ment 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 dis- solved in nitric acid, and the presence of a mercurial salt in the solution confirmed by further tests, Fig. 9. DETECTION OF PHOSPHORUS. 39 The solution to be examined in tlie preceding apparatus, is prepared as follows : The suspected organic matter is treated with cold sulphuric acid of 66° £. until liquefied, and hypochlorite of lime, and dis- tilled 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, concentra- ted and examined as described above. The solution con- tains 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. detectioiv of fhoi^piiorits. 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 magnify- ing 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 por- tion 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 4° LEGAL CHEMISTRY. 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. mistcherlich's method. Mistcherlich's method is based upon the luminosity of the vapors of phosphorus. The suspected niaterials 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 piesent is considerable, the phosphorous acid formed can be collected and its properties tested. dusart's method, as modified by blondlot. 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 phos- phorus 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 ; ^ is a U tube, filled with fragments of pumice stone which are saturated with a concentrated solution of potassa ; ir is a Mohr clamp ; d a screw-clamp ; e a platinum jet. This jet is necessary in DETECTION OF PHOSPHORUS. 41 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 42 LEGAL CHEMLSTRY. clamp d is closed until the acid is forced back into/; and the materials to be examined are then added to the fluid. Upon opening the clamp the liquid passes from/ 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, consist- ing 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 precipi- tate, 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 are contained in the solutions, and this phenomenon totally fails to appear in presence of oil of turpentine. DETECTION OF PHOSPHORUS. 43 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 ih& free state, in the organs fifteen days after death, and even then its isolation can easily be accomplished. For this pur- pose the stomach or intestines, and the articles of food con- tained 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 : ist, 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, pro- duces 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 em- ployed 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 con- tain 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). 44 LEGAL CHEMISTRY. Fig. II. 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 dis- solved in water to which some ammonia is added, and the solution tested for phosphoric acid. This method is an ad- vantageous one as the phosphoric acid formed must originate from phosphorus in ih& free state, and not from any phosphates which, owing to the presence of organic matter, might be con- tained in the bisulphide of carbon solution. It would, how- ever, 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 there- DETECTION OF PHOSPHOROUS ACID. 45 fore 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 re- action 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 con- ducted 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. TJie 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 46 LEGAL CHEMISTRY. of magnesia : the precipitate formed, is washed, heated to red- ness, 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 constitu- ents 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 consist- ence : the operation is then discontinued. If hydrochloric acid be present in the materials under examination, the dis- tillate will have an acid reaction, and, upon addition of solu- tion 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. DETECTION OF ACIDS. NITRIC ACID. 47 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 so- lution 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 treat- ing 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 sub- stances, 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 be- fore the blow-pipe, a mass is formed, which, when moistened 48 LEGAL CHEMISTRY. 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 trans- formation of the iodine set free into hydriodic acid, subsequent- ly disappears. (We have never been able to effect the disengage- ment of sulphurous acid spoken of above when an exceeding- ly 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 phos- phoric acid be present. The precipitate is washed, sus- pended in water and a current of sulphuretted hydrogen passed through the mixture. If the fluid is then filtered, and the ex- cess of sulphuretted hydrogen expelled from the filtrate by boiling, a liquid possessing the distinctive propertiss of a solu- tion 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 DETECTION OF ACIDS. 49 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 j 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 pre- cipitation, 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 alchohol 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 pre- cipitate, 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 : ist. 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 3 ro LEGAL CHEMISTRY. the per-salts mentioned and sufphuretted 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 ; sth, 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 precau- tions. 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 sil- ver. 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, hydro- chloric acid added t(> 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.* In case the latter compound is pres- ent, ammonia will be contained in the distillate. 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 * Ferrocyaniiles and ferricyanides — non-poisonous compounds — likewise, evolve hydrocyanic acid when distilled with a strong acid. Tlieir presence is indicated by stirring a small portion o£ the materials with water, filtering the fluid, acidulating the filtrate with hydrochloric acid, and testing two por- tions : 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. DETECTION OF ACIDS. 51 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 vol- atilized 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 per-salt 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 con- tained 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 solu- tion 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. 52 LEGAL CHEMISTRY. DETECTIOIX OF AI^KAJLIES AIYU AI^KAIillVE 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 car- bonates of soda and potassa are extensively used as pharma- ceutical 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 con- tain the ammonia present. When, however, putrefaction has begun, the detection of this compound does not necessarily in- dicate 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 alco- hol. By this treatment, potassa and soda go in solution, lime, baryta and strontia * — as well as the alkaline carbonates — re- maining undissolved. The potassa and soda are separated from the other salts present by filtering and evaporating the alcohol- ic 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 * Baryta and strontia dissolve in alcohol, but only when they are an- hydrous and the alcohol is absolute, which is not the case here. DETECTION OF ALKALIES. S3 removed by filtration. Some hydrochloric acid and solution of bichloride of platinum are then added to a portion of the filter- ed liquid : in presence oi potassa a yellow precipitate is formed. Another portion is treated with tartaric acid : a white gran- ular precipitate is produced. Hydrofiuosilicic 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 am- monium or carbonate of soda, and small portions of the solu- tion 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 dry- ness, 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 54 LEGAL CHEMISTRY. 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 lat- ter reaction distinguishes baryta from strontia, which is not pre- cipitated 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 sub- stances 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 ob- tained, which is then tested as directed above. DEXSICTIOIV OF CIIIiiORINE:, UKOITIIIVX:, AND lOmNE. 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 potas- sium and starch paste. If the addition of sulphuric acid is necessary in order to produce the above reactions, there is DETECTION OF BROMINE 55 reason to suspect the presence of " chloride of lime" or "■ Eau de yavelle." * BROMINE. In case bromine exists in a free state at the time the au- topsy is made, its presence will be detected by the reddish color and unpleasant odor it possesses. Its isolation is accomplish- ed 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 aque- ous 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 de- tected as directed above. * 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 jfavelle" is the corresponding potassium compound. — Trans. 56 LEGAL CHEMISTRY. IODINE. The detection of iodine is accomplished by a process al- most 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. BETECXIOIV OF META1.S. 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 ac- complished, 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 resi- due 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 pre- sent 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. * * I£ an insoluble residue remains by the treatment with nitric acid, it DETECTION OF METALS. 57 Sulphuric acid is added to the filtrate : if no preci- pitate 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 preci- pitate 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 ad- dition of sulphuric acid, or the filtrate separated from the preci- pitate formed, can contain only silver. Upon adding hydro- chloric acid, this metal is thrown down as a caseous white preci- pitate, 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 de- composition of fluoride of silicum by water, with the solution, before filtering. The precipitate becomes intimately mixed with 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-dis- solved in boiling hydrochloric acid. Upon adding chloride of gold to the solution so obtained, a purple precipitate is formed. Sulphuretted hy- drogen produces a brown precipitate, soluble in sulphide of ammonium, in presence of tin. ^ 3* 58 LEGAL CHEMISTflY. 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 (*) 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 undis- solved washed with dilute hydrochloric acid, and the washings united with the filtrate. The residue i. and the solution 11. are separately exam- ined as directed below. DETECTION OF METALS. jg RESIDUE I. This may contain lead, mercury, tin, bismuth and antimo- ny. 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 de- scribed in the treatment of residue A. The solution, obtained by the action of aqua regia on resi- due I, is treated with sulphuretted hydrogen. The tin and an- timony 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 ammo- nium with nitric acid, lead, copper and bismuth go into solu- tion, mercury remaining undissolved. The liquid is filtered, and the undissolved mercury submitted to the special exami- nation 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. 6o LEGAL CHEMISTRY. SOLUTION II. The solution is concentrated by heating on a water-bath, a small quantity of carbonate of soda cautiously added to a por- tion, 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 pre- cipitate 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 precipi- tate 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 pre- cipitate in solution II., it is certain that arsenic, and no other metal, is present. Under these circumstances, the ammon- iacal 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 am- monia, and a precipitate was formed by the addition of carbon- ate of ammonia to solution II., it is necessary to likewise search for tin, antimony, mercury, copper, bismuth and cad- mium. 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 fil- tered. DETECTION OF METALS. 6i The remaining residue (III.) is washed, labelled, and pre- served for subsequent examination ; ^q filtrate (IV.) is treat- ed as directed below. TREATMENT OF SOLUTION IV. The solution, to which the water used in washing the resi- due 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 i part of car- bonate 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 al- cohol and water. The filtered fluids are now evaporated in order to remove the alchohol, 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 wa- ter 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 pre- cipitate 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 tpeatment with dilute hydrochloric acid, and the residue boiled with con- centrated hydrochloric acid which dissolves the tin present. 62 LEGAL CHEMISTRY. The fluid is filtered and t}\e. filtrate tested for this metal by adding solution of chloride of gold, which, in its presence, pro- duces 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 am- monia added to the filtrate : in presence of copper, the solution acquires a blue color, and gives a reddish precipitate upon ad- dition 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, cop- per, cadmium and bismuth. Upon treating it with nitric acid, all but the sulphide of mercury are dissolved. In case no resi- due 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 forma- tion of a permanent precipitate denotes the presence of bis- muth. In this case, the fluid is filtered, and the alkaline filtrate further tested for copper and cadmium. For this' purpose, cy- anide of potassium is added, and sulphuretted hydrogen con- DETECTION OF METALS. 63 ducted through the filtrate : if cadmium be present, a yellow precipitate is produced, copper not being thrown down in pre- sence 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 ammo- nium added, and the fluid, after being allowed to stand for several hours, filtered. The precipitate may consist of sul- phide of zinc and hydrated oxide of chromium, as well as of traces of sulphide of iron and phosphate of lime. If the sus- pected materials contained a chromate, this salt, in presence of hydrochloric acid and sulphuretted hydrogen, would be con- verted 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 64 LEGAL CHEMISTRY. 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 raanganate that would be present were manganese con- tained 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 : ist., 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 'Cos. filtrate ; if the solution contains cobalt, nickel or manganese — which is improbable — a perma- nent 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. DETECTION OF ALKALOIDS. 65 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. DETECTIOIV OF AliKAIiOIDS AND SOKEE Ilili-DEFIIVED OROAIVIC SVBSTAIVCES.* 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 Z. Uslar and y. 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. STAS'S METHOD. This method is based upon the facts : («), that the acid salts of the alkaloids, especially those containing an excess of tar- * Colchicine, picrotoxine and digitaline. 66 LEGAL CHEMISTRY. taric or oxalic acids, are decomposed by caustic alkalies and by the bicarbonates of soda andpotassa ; (Ji), 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 sub- stances, 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 renderedcertain. ftf 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, y 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 mix- ture thoroughly shaken, and after it has remained at rest for DETECTION OF ALKALOIDS. 67 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 pres- ent. In this case, a solution of caustic potassa is added to the test-tube, the mixture shaken, the supernatanMfi&Er, decanted * into a flask and the remaining solution aglLBSvashed with ether until the last portion fails to leave a residue upon evaporation. The etherial fluids are then united, and two cubic centimetres of wat«r, acidulated with one-fifth of its ■ weight of sulphuric acid, added. This acid retains the alka- loid, 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 alka- loid 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 * The necessity of decanti'Rg etherial and other solutions is advanta- geously obviated by the use of a pipette. — Trans. 68 LEGAL CHEMISTRY. 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 con- sists of the alkaloid present in a state of purity, and can be directly identified by means of the reactions described fur- ther on. 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 tliffiMw-loid is removed ; the ethereal fluids are then united in a ca'psule, 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 vege- table 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 litrie 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 carbon- ate of potassa added, and the mixt«re treated with absolute alcohol, which dissolves the liberated alkaloid, and separates DETECTION OF ALKALOIDS. 69 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 examina- tion. 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 dis- solve 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 contain- ing the oxalates or tartrates of the alkaloids with ether, pre- viously to their separation by means of bicarbonate of soda. By this treatment the elimination of the coloring matter pres- ent — as well as of colchicine, digiiaH?te, 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 con- cluded as usual. In this way the alkaloid is obtained, almost 70 LEGAL CHEMISTRY. 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. I St. The materials to be examined are brought to the con- sistence 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 evapo- rated to dryness over a v/ater-bath : the addition of silica ren- ders the residue friable. 3rd. The residue is boiled repeatedly with amylic alcohol, which extracts all the alkaloid present as well as the fatt)' 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 pres- ent 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 DETECTION OF ALKALOIDS. 71 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 concen- trated 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 acids. 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 js true, preferable ; still, with the exercise of care, ether can also be employed, and, as this process greatly facilitates examina- tions when no clew to the poison present exists and all alka- loids 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 72 LEGAL CHEMISTRY. are digested with dilute hydrocliloric acid, and the mixture filtered. The filtrate is then evaporated to dryness on the water-bath, the residue taken up with pure alcohol, the alco- holic 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. Con- centrated 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 oper- ation is repeated until the residue obtained by evaporating the chloroform is no longer affected by the treatment with sul- phuric 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 moisten- ed 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 strych- nine be present, it will now separate out in crystals. This method is applicable only in presence of a considerable quan- tity of strychnine, and is less serviceable than the one preced- ing. DETECTION OF ALKALOIDS. 73 GRAHAM AND HOFMAN'S METHOD. This method, which is appUed 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 go per cent, alcohol. The apparatus represented in Fig. 12 is employed, in order to avoid a loss of substance in this operation. Fig. 12. The alcohol is filtered hot, evaporated, and the residue obtained treated with a small quantity of solution of potassa, 4 74 LEGAL CHEMISTRY. and then agitated with etlier. Upon spontaneous evaporation, , the ethereal solution leaves the strychnine present in a com- paratively 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 re- commended : 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 hydrochlo- ric 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. IDEIVTIFICATIOIV OF THE At,KAT.OII>. The alkaloid having been isolated by one of the preced- ing methods, it remains to establish its identity. Owing to the small number of reactions characteristic of organic com- pounds, this is a matter of considerable difficulty. There are two cases possible : the alkaloid may either be volatile or fixed. DETECTION OF ALKALOIDS. THE ALKALOID IS VOLATILE. 75 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 hydroch- loric 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 or an homologous base. c. Should the above tests fail to give posi- tive 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 boil- ing, it prdbably consists of nicotine.' aniline. THE ALKALOID IS FIXED. A very minute quantity is dissolved in the smallest possi- ble amount of hydrochloric acid, and an excess of ammonia 76 LEGAL CHEMISTRY. added. Three cases are now possible : (a) A precipitate, in- soluble in an excess of the precipitant, is immediately formed ; {p) 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 eva- porated 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 berberitu. In this case, it will possess a yellow color, and its hydrochlorate will give a reddish-brown precipitate upon addition of sulphide of ammo- nia. Ether dissolves the alkaloid. — A small por- tion is treated with nitric acid. If an intense green coloration is produced, the remaining jjor- tion is dissolved in ether, and an ethereal solu- tion of oxalic acid added. If the precipitate DETECTION OF ALKALOIDS. 77 nov\ Formed does not dissolve upon the addition of c llittle water, there is reason to suppose the presslnce 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, sul- phuric 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 oi tliese tests give but negative results, and the alkaloid is soluble in concentra- ted sulphuricacid, a solution being formed which 78 LEGAL CHEMfgTRY. assumes a reddislM?felet tint when stirred with <^ a glass rod previously dipped in bromine water, !" the presence of delp^^e. is indicated. Ether fails to dissolve the alkaloid. — If the substance is capable of being sublimed, * it con- sists of chichonine. 1). Ammonia produces a precipitate, which redissolves i7i 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 : (i) Nitric acid im- parts a blood-red color to the substance ; (2) if treated with sulphuric acid, it acquires a red- dish 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 : (i) If the substance is treated with a mixture of sulphuric acid and an oxydizing body, such as bichromate of potassa, binoxide of manganese, or peroxide of lead it acqiu^es a — — B • * Cinchonine, when sublimed, condenses in minute brilliant needles. - Trans. al|. ■J ^TECTION OF ALKALOIDS. 79 jjilor, which changes into red and finally P-i'lic € ffo 3. clear yellow ; (2) the addition of biclint^sF of platinum produces a precipitation of t',p^ lllrochlorate. S-t^Bd, however, the substance be only slight- ly sOcjMe in alcohol, and the above reactions fail to^ake place, the presence of solanine. is indicated. In presence of this alkaloid the follow] \(^ reactions will occur : (i) 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 ' i^'y- the aqueous and even acid solution of- its. >'^, salts. '■ ■^^* c. Ammonia fails to produce a precipitate, or redissoives permanently the one formed. The solubility of the alkaloid in ether is as- certained. If it be soluble, it may consist of aconitine, atropine or codeine ; if insoluble, of emetine or morphine. The alkaloid is soluble i7i ether. — If bichloride of platinum fails to precipitate the hydrochlorate from a neutral solution of the alkaloid, and sul- phuric acid causes it to assume a yellow cplor which subsequently changes to a reddish-violet, it probably conlgsts of aconitine: In case bichloride of platinum causes a pre- 8o LEGAL CHEMISTRY. ' cipitate 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 evap- orate. If the alkaloid is deposited during this operation, it probably consists of If this is not the case, there is reason to infer the presence of The alkaloid is insoluble in ether. — If it dis- solves in acetone it probably consists of If acetone fails to dissolve it, the presence of is indicated. The following confirmatory tests should be applied : (i) Upon treating the substance with nitric acid, it acquires a blood-red color ; (2) the addition of a solution of a persalt of iron pro- duces an evanescent blue coloration ; (3) chlo- ride 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) permanga- nate of potassa, if heated with the substance, is reduced and acquires a green color. atropine. codeine. efnetine. morphine. J IDENTIFICATION OF DIGITALINE, PICROTOXINE AND COLCHICINE. It has already been remarked that in exlflftisting the first acid solution with ether — previous to the neutralization, ac- ETECTION OF ALKALOIDS. 8i j;i ; ij >tb Otto's method^colchicine, a weak alkaloid, digita- iilic ife Indefinite mixture, picrotoxine (which appears to possess th.ini_lls,Jfcrties of an acid), and traces of atropine, pass into irtofjether is evaporated on a water-bath to dryness, the reviedfErry-l mass treated with sliglitly warmed water and the so'i i filtered from the undissolved resinous matter. The aqireolis^olution 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 so- lution is now decanted, and the water present removed by means of chloride of calcium. If it is evaporated, a residue containing the colchicine, digitalitie and traces of atropine (mixed possibly with a minute quantity of picrotoxine, which is here left out of consideration) is obtained. a. The alkaline solutio7i, from which the ether has been re- moved, is acidulated with hydrochloric acid and again shaken with ether. The picrotoxitie 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 evapo- rations 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 picrotox- ine. The following reaction is distinctive : If the crystals are dissolved in an aqueous solution of soda and a few drops 4* 82 LEGAL CHEMISTRY. % of " Fehling's solution "* added, a reddish precipitafi prous oxide is formed. b. Provided picrotoxine has not been found, the eiMiihihe w- lution obtained by agitating the alkaline fluid witlfi ^- to be examined for colchicine and digitaline. To thisp t ae residue obtained upon evaporating the solution to dry is taken up with water, and the filtered fluid tested as 1 'o /s : I. It is ascertained if a drop of the solution possesses the bitter taste of digitaline. 2. Another drop is treated with so- lution 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, pos- sibly present, would cause the same reaction ; the test there- fore 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,andthe solution stirred with a glass rod moistened with bromine water : in presence of digit- aline a violet-red color is produced. This coloration is more dis- tinct when a small quantity of the alkaloid and an excess of sul- phuric 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 pro- * An alkaline solution of tartrate of coppe'-, employed in the examina- tion of sugar,' urine, and wine. — Trans. DETECTION OF ALKALOIDS. 8^ duct ^n case this body be present : this, however, is not a very dehc e^test. 7. Finally; it is advisable when the presence of dig- italincps suspected to ascertain its physiological action. For this purpo. }, a minute quantity of the substance is placed upon the heart oi a frog : in presence of the alkaloid, the pulsations are imme«ttely 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 character- istic 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 ex- amination — 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 sul- phate 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 fil- trate 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 crystal- lization from alcohol. An elementary analysis of the alkaloid 84 LEGAL CHEMLSTRY. % \ is now executed. Certainty as to the presence of an iSe.rid- ual alkaloid is attainable only when the execution of thi n con- firmatory test is possible. The reactions previously described can be performed with fifteen centigrammes of substance, i , d this amount is sometimes contained in a cadaver. If but.bne or two centigrammes are at hand, it is still possible to deliect the presence of an alkaloid ; a conclusion, however, as to which can- not be arrived at, especially if the substance found is a liquid or an amorphous body, and one that presents few distinctive properties. III. inETHODS TO BE EmPIiOVED, TVHEIV IVO CliEW TO THE NATITRE OF THE POISOIV PRESEIVT CAN BE OBTAINED. If poisoning has been caused by the administration of a mixture of numerous substances and these greatly diiifer in their properties, it is impossible to demonstrate in an incon- testible manner the presence of each individual poison. This contingency fortunately but seldom arises ; the criminal usual- ly 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 exam- ination into three parts : one portion is preserved, in order to ascert'flin its physiological effects on animals, the chemical anal- sis having failed to give positive results. The other portions are submitted to analysis, but with slightly different objects 86 LEGAL CHEMLSTRY. in view ; one is subjected to a series of tests which are adapt- ed, 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. IIV»ICATIVE 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 treat- ment, 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 remain- ing 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 insolu- INDICATIVE TESTS. 87 ble 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 : (i). 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 pre- cipitate 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. 88 LEGAL CHEMISTRY. (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 possi- bly 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. «. 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 ex- amination contains z. fluoride. I. Nitric acid. — If this acid be present, and a second portion of the residue is heated with sulphuric acid and cop- per, 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 INDICATIVE TESTS. 89 baryta solution {vide : under portion B?j produces the same reaction, inasmucli as otiier 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 car- bonic 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 super- saturated 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 s^ precipitate ioTxas, 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. t- 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 indi- cates the presence of sulphuric acid. 90 LEGAL CHEMISTRY. 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 ; th.e:JtltratehQing 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 am- monia 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 molyb- date of ammonia (vide: detectmi 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. Th& 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 decom- posed by fusion with potassa. The mass is then dissolved in water, and the solution submitted to the following tests : .. 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 immediatel 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 INDICATIVE TESTS. gi iodine is also contained in the fluid, and tlie 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 ex- amination will already contain hydrochloric acid, it is unneces- sary, 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 within 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 92 LEGAL CHEMISTRY. 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 ob- viated, 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 ob- tained, are destroyed by means of nitric acid, and the residual mass examined for soda. If this substance has not been in- troduced into the portion of fluid examined, and is discovered in a quantity largely in excess of the amount normally con- tained 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 an- tidote. 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 or- ganic 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 (includ- ing potassa, which salt has not been introduced into this por- tion of the fluid in any of the preceding operations) by the usual methods. IiVDICATIVE TESTS. g3 (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. (i). The organic matter present is first destroyed by treat- ment 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 sep- arated from the fluid and further examined. The filtered solu- tion is then introduced into Marsh's apparatus, sodium amal- gam 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 examina- tions, 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. 94 LEGAL CHEMISTRY. 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. hetekmiiyative tests. In many instances the tests we have termed indicative be- come 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 accom- plished ; 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 abun- dance, there is reason to infer that the poisoning has been caused by an acid ; or, if, after the neutralization of the origi- nally alkaline solution with an acid, potassa or soda are discov- ered 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 recep- tion of iodine or bromine. According to the indications furnished, iodine, bromine, one, or all of the acids, the caustic alkalies, etc., are then de- tected by means of the methods to be employed in cases where the expert has a clew to the poison present. In this manner. DETERMINATIVE TESTS. 95 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 plac- ed 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 [V) 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 ap- plying 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 suit- able 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 oi phosphorus, and it is necessary to examine a separate portion of the original substance for this body. IV. MISCEIiliAIVEOirs EXAMIIVATIOIVS. DETEKMIIVATIOIV OF THE NATURE AND COK.OR 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 conse- quently 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. EXAMINATION OF HAIR. The hair has been blackened. 97 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 : 1°. The hair is well rubbed with a pomade, in which finely pulverized charcoal is incorporated. This preparation, which is sold under the name of " melainocome," possesses the dis- advantage of soiling the fingers and clothing, even for several days after its application. 2". 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 al- lowed to remain in contact with a solution of sulphuretted hydrogen. 3" The same operation is performed, a lead compound being substituted for the bismuth salt. 4°. A mixture of litharge, chalk, and slacked lime is ap- plied, and the head covered with a warm cloth. The hair is afterwards washed, first with dilute vinegar, then with the yolk of an egg. 5°- The hair is first cleansed with the yolk of an egg, and then moistened with a solution of plumbate of lime ; or, 6°. It is moistened with a solution of nitrate of silver, to which a quantity of ammonia sufficient to dissolve the precipi- tate first formed has been added. The first method merely causes a mechanical admixture of a coloring matter with the hair. In the four succeeding pro- cesses, a black metallic sulphide is produced ; either by the subsequent application of a solution of sulphuretted hydro- gen, or by the action of the sulphur normally present in the hair. 5 9S LEGAL CHEMISTRY. 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 " milariiocome," 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 ac- complished by means of the methods used for the detection of metals is 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. EXAMINATION OF HAIR. 99 The expert may therefore be able to observe indica- tion that will greatly assist him in arriving at a definite con- clusion. 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 de- colorized 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 sometimis 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 *^° 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 o.oi m.m., and are transparent, whatever ma/ be their color. The hair of ruminants is short and stiff, and is character- ized by containing cavities filled with air. Wool, however, 100 LEGAL CHEMfSTRY. forms an exception, as it consists of entire hairs, homogeneous in appearance and possessing imbricated scales, which bestow upon it tlie 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 occa- sionally become detached, in the same manner as a twig separates itself from the parent branch. EXAMINATIOIV OF FIRE-ABMS. {Proposed by M. Boutigny.) The examination of fire-arms is sometimes useful in deter- mining 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 ; /. e., whether common gunpowder, gun-cotton or white gunpowder (prepared by mixing yellow prussiate of potassa, chlorate of potassa and sugar) have 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 moist- ure 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 EXAM/jVAT/ON of fire-arms. 1 01 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 pulveru- lent 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 wash- ings passed through filter paper which has previously been well washed, first with pure hydrochloric acid, then with dis- tilled water. The filtrate is next divided into three portions, and these separately examined for : (i) sulphuric acid, by addition of chloride of barium ; (z) 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 (3I -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 subace- tate 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 102 LEGAL CHEMISTRY. crystals have been discovered on the barrel or fire-pan, the wea- pon has been discharged more than tivo, 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, tut 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 imtnediately after its discharge without having bee?i previously washed, the portions of the wad- ding wliich have come in contact with the barrel will possess a greyish-black color during the first four days, the color grad- ually 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 befo7-e 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 da)-. 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 itntni'diafely after being washed, the wadding possesses a greenish-yellow appearance for the first EX A MINA no A ' OF FIRE- A RMS. j 03 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 I 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 occa- sionally 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 I04 LEGAL CHEMISTRY. value, save in the rare instances where a gun provided with a fire-pan, and charged witli ordinary powder, is under examina- tion, and the question of the lapse of time since the discharge of a weapon must remain undetermined so far as scientific tests are concerned. UETECTIOIV OF BIUMAIV REMAINS IN THE ASHES OF A F1RE.PI.ACE. This class of examinations is particularly necessary when the crime of infanticide is suspected. As the complete incine- ration of a cadaver is a long and difficult operation, it frequent- ly occurs that bones — ^partially or completely carbonized, but I'etaining their original form — are discovered by the careful examination of the ashes of the fire-place in which the com- bustion was accomplished. When this is not the case and complete incineration and disaggregation have occurred, recourse must be had to the indi- cations 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 reac- tions given by ashes of animal bones being identical with those produced by the ashes of a human body. Two tests are em- ployed to detect the presence of bones in the residue left by the combustion of animal matter. I. 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 mate- rials, cyanide of potassium will be present in the aqueous solution. In order to detect this salt, the fluid is acidu- lated with hydrochloric acid, and a solution of persulphate of iron added : the formation of a blue precipitate indicates the presence of the cyanide. EXAMhWATION OF WRITINGS. 105 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 detec- tion 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 precipi- tate 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 r.itric 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 reac- tion is, however, valueless, inasmuch as coal and certain vege- table ashes likewise evolve the gas when subjected to the same treatment. EXAMIIVATIOIV OF WRITIIVeS. 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 cer- tain words, in order to modify the signification of a sen- tence. Writings are altered either by erasure or by washing. Erasure, although more easily executed, is seldom employed, 5* io6 LEGAL CHEMISTRY. 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 imm2rsion in a solution of gela- tine ; at present, however, a soap of resin, or wax, and alumina (a little starch being addiid) 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 employ- ed ; the det2ction of its attempted restoration is also a matter of less difficulty, as gelatine would be employed for this pur- pose, 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 : 1°. 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. 2". 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. EXAMINATION OF WRiriKGS. 107 opaque points are observed, it is almost certain tliat 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. 3". The paper is dried and the above operation repeated with alcohol of 87 percent. 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 trans- parent. 4°. 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 sug- gested 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. S°. It is ascertained whether the paper possesses an acid reac- tion. If so, its acidity may result from the presence of hydro- chloric 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 io8 LEGAL CHEMISTRY. acid only in certain spots, and tliese points produce a red coloration upon blue litmus paper, having tlie 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. 6°. 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 examina- tion. 7". If the paper possesses a friable appearance, it has pos- sibly been waslied 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 dis" tilled 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 concen- trated by heating as to cause the carbonization of the paper. EXAMINATION OF WRITINGS. 109 8° 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 appear- ance. This would be caused by the escape of carbonic acid, originating from the action of sulphuric acid upon the car- bonates contained in the water used in the manufacture of the paper. 9°. 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 writ- ten. 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 immedi- ately 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. 10°. 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 Freigne, which took place at Montpelier in 1852. A '■'■ trompe-roeil" 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 no LEGAL CHEMISTRY. 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 sus- pected 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. EXAMIIVATIOIV OF WKITINOS IIV CASES WHERE A SYM- PATHETIC IIVK 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 adetates of lead, and other metals which give a colored sulphide when treated with sulphuretted hydrogen. Characters written with a solu- tion of ferrocyanide of potassium acquire a blue color, if EXAMINATION OF WRITINGS. m 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 sympa- thetic 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 allow- ed 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 sulphuret- ted hydrogen, it is probably that either a solution of ferrocy- anide of potassium or a persalt of iron has been resorted to. Each of these solutions is separately applied on a small por- tion 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 preced- ing operations, it must not yet be concluded that a sympa- thetic ink has not been used, although we are left without further recourse to chemical tests. Numerous organic com- pounds 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 an- other ink absolutely impossible. It is therefore often neces- 112 LEGAL CHEMISTRY. sary 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 writ- ten with a pulverulent substance suspended in water or muci- lage, they may often be observed upon examining the transpar- ency 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. VAIiSIFICATION OF COIIVS AlVD AI/X/OYS. 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 laminae 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. EXAMINATION OF COINS, ETC. 113 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 ex- hibited to the author an alloy, prepared by him, pcrssess- ing the density, sonorousness and lustre of silver ; the com- position 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 opera- tion requires considerable practice and the methods employed are to be found in all treatises on quantitative analysis, we will not reproduce them here. 114 LEGAL CHEMISTRY. EXAMIIVAXIOIV OF AIiIMENTAKY AIVD PHARMACEU- TICAIi fSUBSTAWCES. 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 preced- ing, 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 co- herent 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 FLOUR AND BREAD. 115 ■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 introduc- tion 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 propor- tion, 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, con- siderably increased. The bread of the Paris city bakeries contains 40 per cent, of water — the crumb, which forms f of the weight of the bread, containing 45 per cent. ; the crust, which constitutes the remaining \, containing 15 per cent. In army bread 43 per cent, of water are contained — the crumb, which constitutes f of the weight of the bread, holding ii6 LEGAL CHEMISTRY. SO per cent. ; the crust which forms the remaining ^, con- taining 15 per cent. The addition of common salt naturally increases the pro- portion 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:* 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. Buck-wheat flouri Linseed-meal. Mineral substances (plaster, chalk, lime, alum, and sulphate of copper). 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. * 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 cop- per, plaster, kaolin, etc. — Trans. FL O UR AMD BREA D. 117 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 appear- ance : 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 other- wise badly prepared, the gluten is granulous, difficult to collect in the hand, and somewhat resembles flint-stone in appear- ance. 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 yellow- ish 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 buck-wheat 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 ii8 LEGAL CHEMISTRY. 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 com- pound. 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 ; other- wise, 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 so- lution used does not contain more than 2 percent, of the salt. The results obtained by the above operation should be con- firmed by a microscopic examination. FLOUR AND BREAD. [19 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 addi- tion 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.* 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 solu- tion. Rice and Corn. — If rice or corn meal have been mixed with the flour, angular and translucent fragments (Fig. 14) are ob- served in the microscopic examination. Corn meal acquires a yellow color, if treated with dilute potassa solution. * 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, LEGAL CHEMISTRY. MISCELLANEOUS TESTS. Linseed and rye meals. — If linseed meal is moistened with an aqueous solution containing 14 per cent, of potassa and ex- amined 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 lin- seed and rye meals is simultaneously effected by exhausting the suspected flour with ether, then filtering the solution and allow- ing 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 sub- stance having a fine red color ; but it remains unaltered, if entirely due to linseed. In case the oil becomes solid- ified, the mercury salt present should be removed by wash- - ing with water, the residue taken up with boiling alcohol of 36" B. and the solution filtered : upon evaporating the alco- holic filtrate, a residue is obtained consisting of the linseed oil present. Bitckiuheat. — Flour adulterated with buckwlieat 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 glu- ten 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, analo- gous 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 FLOUR AND BREAD. 121 detection, the flour to be examined is digested with alcohol of 35° B. : if the flour be pure, the alcohol remains limpid : it ac- quires 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 resi- due, 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 rapid- ity with which they change the properties of the latter, and communicate to it tlieir characteristic odor — noticeable upon treating the flour with a little boiling water. Their presence is also easily detected by the distinctive properties of the veg- etable 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 mat- ter 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 fermenta- tion, at a temperature of 18° to 20" : in case leguminous sub- stances are not present, lactic fermentation occurs and the odor of sour milk is alone perceptible ; if, on the other hand, legumena 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 legumin- 6 122 LEGAL CHEMISTRY. ous 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 emar- ginated 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 ad- dition of nitric, hydrochloric, acetic, oxalic, and citric acids ; upon protracted boiling in water, it loses its property of be- ing 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:. 1 ^f ■j__3'^'*«^s=irtjj?- are easily recognized. Ihe mixture ^M , '^^„,:_^^^- on the glass may also be treated with an " ' , "5 , ' ,_^ aqueous solution of potassa (containing I;" ^^^^< "■"=^~; ' 1 — 10 per cent, of the salt), or with dilute hy- ^' '^ "^ ',, ^,, drochloric acid : these reagents dissolve the starch present, leaving the reticulated F'S- 15- . . . . . 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. FLOUR AND BREAD. 123 Meals prepared from beans, horse-beans, and lentils, con- tain a tannin which imparts a green or black color to salts of iron. The coloration is rendered very sensitive if a rather con- siderable 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 (Jerrico-ferrous sulphate) : the reaction imme- diately 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 sus- pected flour is placed upon the edge of a capsule containing nitric acid, the latter heafed, and, as a yellow coloration ap- pears, the acid removed and replaced by ammonia. The cap- sule is then set aside : if the flour is adulterated with either of the above vegetables, reddish spots, which are easily percepti- ble 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 witli 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 pos- sess 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. 124 LEGAL CHEMISTRY. 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 chief- ly consists of phosphates of potassa, soda, magnesia and lime, of sulph ates, 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 con- tains 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 sub- stances, that are fraudulently added to flour, are ground cal- cined bones, sand, lime, plaster, alum, and sulphate of copper. The two last named salts are almost invariably added in small quantities ; alum render^ the flour white, even when used in the proportion of one per cent. ; sulphate of copper is added FLOUR AND BREAD. 125 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 ves- sel, placed upon a fragment of plaster, and allowed to drw 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 form- ed. 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 pos- sessing 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 aud magnesia; vegetable ashes. — Car- bonic acid is always evolved, upon treating flour with hydro- chloric acid. If the base present be calcium, upon adding oxa- late of ammonia to the filtered solution — ^which has previously been neutralized with ammonia — a white precipitate, possess- ing the properties mentioned above, will be formed ; in case 126 LEGAL CHEMISTRY. 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 — /. e. carbonates of the al- kalies — 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 strong- ly 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 fil- trate 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 chlo- ride of barium ; in the other, alumina by adding a solution of potassa, which gives with its salts a white gelatinous precipi- tate, soluble in an excess of the reagent.* * I£ 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 hy- drochloric acid, the filtered solution evaporated to dryness, and the residue FLOUR AND BREAD. 127 g. Sulphate of copper. — About 2 00 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 solu- tion 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 precipi- tate of ferrocyanide of copper.* treated with hydrochloric acid, which now leaves the silica present undis- solved. The acid solution is then filtered, nearly neutralized with carbon- ate o£ soda, and an alcoholic solution of potassa added in excess. The earthy phosphates present are now precipitated, alumina remaining in solu- tion. The use of aqueous potassa in this case — as well as in the case men- tioned 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 co- balt 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 \nd phosphate, and the alumina is then precipitated as usual by carbonate of ammonia. — Trans. * According to Wagner, if the ash, obtained by incinerating the adul- terated bread, is washed with water, shining spangles of metallic copper are separated. — Trans. 138 LEGAL CHEiMLSTRY. FIXED OILS. Olive oil designed for table use is frequently adulterated with the oils of poppy, sesame', pea-nuts, and other nuts. Olive oil, intended for manufacturing purposes, is often mixed with colza and nut oils ; colza oil, in its turn, is adulterated with poppy, cameline and linseed oils, more frequently with whale oil ; hemp-seed oil, with linseed oil, etc. The methods em- ployed in the detection of these adulterations are far from satisfactory. 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 den- sities 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 j 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^ex- amined, as well as to a sample of pure olive oil. The two samples are then allowed to stand in a room where the tem- perature 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 inver- sion. If the sample under examination is free from adultera- tion, 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. FtXED OILS. 129 c. Fifteen grammes of the oil are mixed in a glass vessel with the same amount of strong sulphuric acid, the tempera- ture of the two liquids being previously observed. The mix- ture is stirred with a thermometer, and the maximum tempera- ture noted : pure olive oil produces an elevation of temperature *^^ 37-"7 j pure poppy oil, an elevation of 70. "5 ; and a mixture of the two an elevation of temperature intermediate between 37. "7 and 7o.°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 sesamd or nut oils, 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 sesame, 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 \ of its volume of a solution of caustic soda of sp. gr. I.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 de- scribed 'above. Colza oil is recognized by mixing 5 volumes of the sample to be examined, with i volume of sulphuric acid of sp. gr. 1.65s • ^^ colza or nut oils are present, a brown coloration ensues ; under the same circumstances, pure olive 6* I30 LEGAL CHEMISTRY. oil assumes a pale greenish hue. In case the sample ac- quires 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 colora- tion, and nitric acid fails to change it, the presence of oil of colza is indicated. EXAMINATION OF COLZA OIL. a. The oil is treated with sulphuric acid of sp. gr. 1.475 ^^ just described. In presence of linseed oil, a green coloration ensues ; whale oil and fish oils, which are frequently present, exhibit a red coloration,^ When treated with an acid of sp. gr. 1.530, linseed oil gives a dirty grey ; fish oils a red color- ation. b. The sample is next treated with nitric acid of sp. gr. 1.330 : pure colza oil is not affected ; if poppy and fish oils are present, the sample acquires a red tint ; linseed oil would produce a green hue, changing subsequently to brown. In case the red coloration imparted by nitric acid is also formed upon addition of sulphuric acid, fish oils are present ; the latter acid produces no change of color, however, if the adul- teration used is poppy oil. Cameline oil fails to exhibit re- actions that are adapted to its identification. 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 advis- able 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. FIXED OILS. 131 at the same time, an artificial mixture of tlie two pure oils to the same treatment, and comparing the results obtained. EXAMINATION OF LINSEED OIL. Linseed oil is occasionally mixed with rape-seed oil. The adulteration is detected by mixing the sample under examina- tion with sulphuric acid containing 90 per cent, of the pure acid, and noting the elevation of temperature caused : linseed oil gives an elevation of 74" ; rape-seed oil one of 37. °2. The tests enumerated above are of a very general charac- ter ; exact methods for detecting the presence of fixed oils are, as yet, unknown. 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, and, even then, the exercise of care is indispensable. 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 sus- pension ; the caseine, for the greater part, is in solution, only a small portion being present in an insoluble suspended con- dition. 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, con- taining a sufficient quantity of albumen to coagulate upon heating. The normal density of milk is 1.030, water being i.ooo; the density rising to 1.036, if the fluid has been skimmed. Good milk contains, on an average, 3.7 per cent, of 132 LEGAL CHEMLSTRY. butter; 5.7 per cent, of lactose, and leaves upon evapora- tion 7.5 to 9.5 per cent, of solid matters.* The most common adulteration of milk consists in the addition of water. This fraud is detected by means of an areometer {ladodensimeter) which gives directly the specific gravity of the fluid under examination. Should the density bs 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 con- sists 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 t'.vo 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 * The Briti.sh 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. MILK. ,33 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 Ifeen separated. 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: yoiirn. de Phartn., Novembre 1854, and Bulletin de I'Academie de Medecine, Paris, 1854. xix., p. iioi). Previously to the introduction of Marchand's apparatus, use was made of the lactometer, which consists simply of a grad- uated glass tube, in which the suspected milk is allowed to re- main for 24 hours, at a temperature of 15°. After the lapse of this time, the cream present completely separates as a super- natant 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 fre- 134 LEGAL CHEMISTRY. quently 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 con- taining 40 grammes of pure crystallized sulphate of copper, 600 or 700 grammes of caustic soda lye of sp. gr. 1.12, and 160 gram- mes of neutral tartrate of potassa. The sulphate of copper and tartrate of potassa are previously dissolved separately in a Utile water, the three solutions united, and water added until the fluid acquires a volume of 11 54. 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 cen- timetres of the copper solution, diluted with 40 cubic centime- tres 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 addi- tion 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 repeat- ed, the milk under examination being substituted for the solu- tion of pure lactose. The quantity of milk necessary to de- colorize 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 estima- tion 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 addi- tion of a known amount of sand, or ground glass, is advisable. MILK. 13s 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, bibarbonate of soda, emulsion of almonds, gum tragacanth, gum arable, 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 sub- sides 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 recog- nized. 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. I^ it is passed through a gauze, small opaque lumps are separated. When examined under the microscope, numerous minute globules, having a diameter of ^J^ of a mill- imetre, are observed, and, upon adding a few centigrammes of amygdaline to one or two grammes of the milk, the character- istic odor of bitter almonds is produced. Gum tragacanth. — When shaken in a glass flask and al- lowed to rest, the milk deposits on the sides small transparent lumps, which usually present a slightly elongated or angular form. Gum arable. — The addition of alcohol produces an abun- dant white opaque precipitate. Starch, flour, decoction of barley, rice, etc. — Upon boiling the 136 LEGAL CHEMISTRY. 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 fermen- tation 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 con- sists 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 solu- tion of chloride of barium. This test may he confirmed by a microscopic examination of the milk, when the peculiar ap- pearance of cerebral matter will be detected.* WINE. The most common adulteration to which wines are sub- jected 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 con- stituent of wine. In Paris the following method is usually employed : As soon as the wine is confiscated, it is ascer- * Fragments of nerves, and other organic structures, are frequently ob- served in tJiis examination. — Trans. WINE. 137 tained what kinds of wine are manufactured by tlie inculpated dealer, and a statement obtained from him, giving the propor- tions of alcohol, etc., contained in the various brands. A wine is then prepared, according to the information received, an es- timation of the alcohol contained in the prepared sample made, and the results compared with those furnished by a similar ex- amination 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 af- ter 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 pro- portion of this salt would be sensibly decreased by the addi- tion 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 decol- orization. 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. For- eign 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 va- rious other colors upon the addition of the alkali.* * Cotlini (Ann. du genie civil, No. 3, 1873) states that the following 138 'LEGAL CHEMISTRY. The indications furnished by the above test are rendered valueless, if the wine has been artificially colored by the addi- tion 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 be- ing 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 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 (C Privet violet-blue " Turmeric light-blue (( According to M. de Cherville [Quar. Jour. Sc), a bright violet colora- tion is produced in the above test, if litmus be present. Fuchsin is separated by treatment with subacetateof lead and addition of amylic alcohol [Jour, de Ph. et de Ch. Mar. 1873). — Trans. WINE. 139 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 con- tained exactly the proportion of carbonic acid ordinarily present in wine. It remains to mention the methods employed in determin- ing 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 (akoomefer), 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 temper- atures. Gay-Lussac has compiled a table which indicates at once the required correction ; the following formula can also be used : x = c + 0.4 /, where x is the quantity of alcohol present in the sample ; c the degree indicated by the alcoholmeter, and i 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 tem- perature at which the estimation is made is greater or less than 15°.* In case the wine to be examined contains substances other than water and alcohol, which would affect its density, it is * Tralles alcoholmeter is almost exclusively employed in this country. — Trans. 140 LEG A L CHE MIS TR Y. necessary, before making use of the alcoholmeter, to distil tlie sample and subsequently examine the distillate, which will con- sist of a simple mixture of water and alcohol. Usually the distillation is discontinued as soon as one-third of the sam- ple has passed over, and a quantity of distilled water, suffi- cient to render the volume of the mixture equal to the original volume of the wine, added to the distillate : the fluid re- maining 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. 16) used in exam- inations of this charac- ter, consisting of a flask, closed with a gutta-per- cha 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. In order to estimate the cream of tartar, the wine is evap- orated 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 i gr. of cream of tartar exactly saturates 9.75 cubic centimetres of a solution VIA' EG A R. 141 containing 100 grammes of sulpliuric acid of 66° B., and 1800 grammes of distilled water. Tlie detection of toxical substances, often contained in wine, is accomplislied by the metliods described under the head of detection of poisons. VINEGAR. Vinegar is frequently adulterated with water, and occa- sionally 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 AI. 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 dex- trine, and the addition of iodine fails to cause a blue colora- tion. 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 neu- tralize a measured quantity of the vinegar, is ascertained, or 142 LEGAL CHEMLSTRY. the vinegar is supersaturated with solution of baryta, the ex- cess 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 adul- terated. The substances used for this purpose are : crystal- line sulphate of lime, boric acid, mannite, sugar, starch, sali- cine, stearic acid, and the sulphates of cinchonine and quini- dine. 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 va- rious 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 sul- phate of quinine is completely consumed ; whereas, the min- eral 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 .SULPHATE OF QUIiXINE. 143 produced. Carbonic acid is tlien passed through the fluid, in order to precipitate the excess of baryta as insoluble carbon- ate, the fluid saturated with ammonia, to throw down the quinine which may have been redissolved 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 fol- lowing : Several grammes of ammonia and ether (which has pre- viously been washed with water) are added to one or two gram- mes of the salt under examination, the mixture thoroughly agitat- ed, 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, remain- ing suspended between the layers of the two fluids. The ether is next removed by means of a stop-cock funnel, evap- orated to dryness, and the weight of the residue obtained de- termined. 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 de- composition when solutions of oxalate of ammonia and sul- 144 LEGAL CHEMISTRY. phate of quinidine are mixed. Under the same circum- stances, 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 sepa- rated 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. EXAraiNATiour or bk.ood stains. This branch of legal chemistry formerly gave but very un- reliable 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 dis- tinctive 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 produc- tion of small characteristic crystals, termed haemiii crystals, and in the use of the spectroscope. Crystals of haemin (first discovered by Tcichmaii) are formed when dry blood is dis- solved in concentrated acetic acid, and the solution evapora- ted to dryness : they are of a brownish-red color. Brilcke first suggested an analytical method, based upon this property of BLOOD STAINS. 14, blood, which is equally characteristic and sensitive : It is only necessary to dissolve a minute portion of the matter to be exam- ined (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 magni- fying power of 300 diameters. If the crystals originate from fresh blood, they appear as represented in Fig. 17 ; crystals from old blood are represented in Fig. 18. Fig. 17 Fig. 18. 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 Brucke and by Erd- man. 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 7 146 LEGAL CHEMISTRY. 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 allow- ing 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 dis- solve anything, and the residue will not produce crystals when treated with acetic acid. In order to remedy this difficulty Briicke operates directly upon the stained woven or ligneous fibre, or the matter lemoved 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 tlie glass, a trace of chloride BLOOD STAINS. 147 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 dis- tance above a gas burner. The fluid is examined from time to time under the microscope : when it is sufficiently con- centrated, crystals, presenting the appearance represented in Figs. 17 or 18, will be observed. These are especially well-de- fined, 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 con- firming 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 chio- 148 LEGAL CHEMISTRY. ride 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 fav- vorable 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 treat- ed, 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 spectro- scope, and a ray of diffused light (or better, light reflected from a heliostat) made to pass through the part of the glass contain- ing the residue. If the stains originate from blood, the ab- sorption lines of haemoglobin, consisting of two large dark bands, to the right of the sodium line {Fraumhofer' 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 pre- viously spoken of as being formerly exclusively employed ; these are the following : a. J^ to I . 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 BLOOD STAINS. 149 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 pos- sible. Unfortunately sulphate of iron gives the same reaction.* b. Upon heating the fluid obtained by treating the stains with cold water in a test-tube, its brown or reddish color disap- pears, 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 con- taining 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. \i the fluid is acidulated with a few drops of acetic acid, and a drop of ferrocyanide of potassium added, a white pre- cipitate, 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-precip- itated 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. * I^iresh gluten, gum arable, and caseine also cause the blue coloration. — Trans. 150 LEGAL CHEMISTRY. /■ Should the stains have failed to be affected by cold wa- ter (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 chlo- rine 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 soltition that leaves upon evaporation to dryness a residue containing iron, which gives a blue coloration with ferrocyanide of potassium, and a red coloration with sulphocy- anide of potassium. h. The coloring matter of blood dissolves in boiling alco- hol, to which sulphuric acid has been added, to a brown di- chromic 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, BLOOD STAINS. 151 the mass heated with iron-filings and water, the fluid filtered, and the filtrate then acidulated with hydrochloric acid : fer- rocyanide 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 discrim- inate chemically between human and animal blood. M. Barruel, it is true, is able, not only to accomplish this, but also to dis- tinguish 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 dif- ferent 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 ex- amination ; when, however, the stains are tolerably recent, they may be detected by examining the moistened stained cloth, directly under the microscope : a discrimination between an- imal and human blood is then possible : corpuscules of human blood possess the greater size : those of the sheep, for in- stance, have only one-half the diameter of the former. It is, however, but seldom that this distinction can be made use of.* * Menstrual blood is recognized by the presence of epithelial cells. — Trans. 152 LEGAL CHEMISTRY. EXAMIIVATIOIV 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 circum- stances, 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 dis- tinctive stale odor of fresh semen is sometimes emitted, but this characteristic is usually obscured by the presence of for- eign 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 sub- stances. SPERMATIC STAINS. 153 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 fila- ments, 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 whicli 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 pres- ence 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 pro- duced by semen. Of the various methods for obtaining from the stains a 7* 154 LEGAL CHEMISTRY. preparation adapted to the microscopic examination, the one proposed by M. Charles Robin is the most simple and reliable. A strip, I 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 moist- ened 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 afnd 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 exist- ence 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 alengthof 0.04041 to 0.04512 millimetre ; the anterior extrem- ity presents an oval enlargement, either round or pyriform, ex- hibiting 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 tire 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. SPERM A TIC STAINS. 15s 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 spermato- zoa and globules of mucus. d. Crystals of phosphate of magnesia, varying greatly in size ; the largest are from o.mm. 001 to o.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 hydro- chloric 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 156 LEGAL CHEMISTRY. 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 com- pletely as possible from the stained cloth, and determining the presence of the spermatozoa by means of the micro- scope. 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 stain- ed ; usually in the interior, but sometimes also on the ex- terior, 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 circum- stances 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 obtain- ing 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 I'approvisionnement de Paris. Paris, 1859. Angell and Hehner ; Butter ; its analysis and adulterations. London, 1874. Anglada ; Traits de toxicologie. ~ Atcherly ; Adulteration of food. Bandein; Die Gifte und ihre Gegengifte. Beck ; Elements of medical jurisprudence. Bellini ; Lezionis perementali di Tossicologia. Bergman ; Zur Kentniss der putriden Gifte. Bernard ; Le9ons sur les substances toxiques. Billard; Considerations medico-legale sur les les irritants. Blondlot ; Sur la recherche de I'arsenic par la methode de Marsh. Nancy, 1857. Ildd ; Sur la recherche toxicologique du phosphore par la coloration de la flamme. Nancy, 1861. Ibid; Sur le dosage de I'antimoine dans les recherches toxicologiques. Nancy, 1865. Boettcher; Ueber Blutkrystalle. Dorpat. 1862. Bousels ; Ein Beitrag zur Analyse des Arsens, vorzugsweise in gericht- lichen Fallen. Kiel, 1874. Borie ; Catechisme toxicologique. Tuelle, 1841. Bouchardar et Quevenue ; Du lait. Paris, 1857. Bowman and Bloxam ; Medical chemistry. London, 1874. Paris, 1835. London, 1874. Basel, 1869. Albany, 18^1. Firenze, 1865. Dorpat, 1868. Paris, 1857. empoisonnements par Paris, 1821. 158 LEGAL CHEMISTRY. Briaiid et Chaude ; Manuel complet de medicine legale ; contenant un manuel de chimie legale. Paris, 1873. Buchner; Toxikologie. Niiremburg, 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 toxicologic. Paris, 1844. Chiaje; Tossicologia. Napoli, 1835. Chaussier; Medicine legale. Paris, 185S. Chevalier ; Dictionaire des alterations et falsifications des substances alimentaires, medicamenteuses et conrimerciales, avec I'indica- tion des moyens de les reconnaitre. Paris, 1856. Ibid; Essais practiques sur I'examen chimique des vins, considere 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 I'empoisoimement par I'arsenic. Paris, 1842. Cotter; Adulteration of liquors. N. Y., 1874. Cottereau ; Des alterations et des falsifications du vin, et des moyens physiques et chimiques employes pour les reconnaitre. Paris, 1851. Cox ; Poisons ; their effects, tests and antidotes. London, 1852. Calbrush; Lectures on the adulteration of food, and culinary poisons. Newburg, 1S23. Dalton : Adulteration of,food. London, 1857. Divergie; Me'dicine legale. Paris, 1S52. Dragendorff; Beitrage zur gerichtlichen Chemie einzelner organis- chen 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 Lebenbediirfnisse, ihre Aechtheit und Giite ; Verunreinigungen, Verfal.^chungen, etc. Breslau, 1846. Ibid ; Die Priifung chemischer Gifte. Breslau, 1871 Ibid ; Handbuch der angewandten gerichtlich-chemischen Analyse der chemischen Gifte ; ihre Erkennung in reinem Zustand und in Gemischen betreffend Leipzig, 1S73. Duflos u. Hirsch ; Das Arscn ; seine Erscheinung. u. s. w. Breslau, 1842. Dupasquier; Consultation medico-legale relative a une accusation d'empoisonnement par le plomb. Lyon, 1843. Brhard ; Die giftigen pflanzenalkaloiden und deren Ausmittelung auf mikroskopischem Wege. . Passau, 1867. Euleuberg: ; Die Lehre von den schadlichen und giftigen Gasen. Braunschweig, 1849. Plandin ; Traits des poisons. Paris, 1852. APPENDIX. 159 Flandin et Danger ; De Tarsenic. Paris, 1853, Fop ; Adulteration of food. London, 1855, Praise; Alimentation publique; ]e lait, ses falsifications, etc. Nancy, 1864. Frank; Manuel de toxicologic ; traduit de I'alleraand par Vrankan. Anvers, 1803. Fresenius ; AufSndung unorganischen Gifte in Speisen, u. s. w. Braunschweig, 1856, Friedrioh ; Die Verfalschung der Speisen und Getranke. Munster, 1859. Galtier; Traits 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 Pa lis, 1844, Gerhardt; Precis d'analyse pour la recherche des alterations i-l falsifica- tions des produits chimiques et pharmaceutiques. Paris, i860, Garland ; Precis d'analyse chemique qualitative. I'aris, 1855, Gmelin ; Allgemeine Geschichte der thierischen und mineralischen Gifte. Erfurt, 1806. Gorup-Besauez ; Anleitung zur qualitativen und quantitativen zoochemischen Analyse. Braimschmeig, 187 1. Gosse; Des taches, au point de vue medico-legale. Paris, 1862. GrifSu ; The chemical testing of wines and spirits. London, 1872, GrifSth and Taylor; A practical manual of the general, chemical, and microscopical character of the blood, etc. London, 1843 Guerin ; Nouvelle toxicologic. Paris, 1826 Guy ; Principles of forensic medicine. London, 1843 Gwosden; Ueber die Darstellung des Hamin aus dem Blut und den qualitativen Nachweis minimaler Blutmengen. Wien, 1866, Hager; Untersuchungen. Leipzig, 1873. Hartung-ScliTwarzkoff ; Chemie der organischen Alkalien. Miinchen, 1855, Hassall ; Adulteration of food London, 1855. Van Hassett; Handbuch der Giftlehre. Braunschweig, 1862, Helwig; Das mikroskop in der Toxikologie. Mainz, 18' Herman; Lehrbuch der experimentellen Toxikologie. Berlin, 1875, Hitzig; Studien iiber 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 toxicologic du bichromate de potasse. Strasbourg, 1861. Jones (H. Bence) ; Chemistry of wines London, 1874. i6o LEGAL 'CHEMISTRY. Kllincke ; Die Verfalschung der Nahrungsmittel, Getranke, etc. Leipzig, 1858. V. Kupffer ; Handbuch der Alkoholometrie. Wien, 1866. de Lapparent; Les moyens de constater la puret^ des principales huiles fixes. Cherbourg, 1855. Lefort ; Etudes chimiques et toxicologiques sur la morphine. Paris, 1861. Legrand ; Traite de medicine l%ale et de jurisprudence medical. Paris, 1873. Letheby; On food. N. Y., 1872. Ler-win ; Toxikologischen Tabellen. Berlin, 1856. Liebreich ; Outlines of Toxicology. London, 1875. Iiindes; Beitrage zur gerichtlichen Chemie. Berlin, 1853. Lunel; Guide pratique pour reconnaitre les falsifications et alterations des substances alimentaires. Paris, 1874. Malle ; Essai d'analyse toxique ge'nerale, Strasbourg, 1838. Marset; Composition, adulteration, and analysis of food. London, 1856. Marshall; Remarks on arsenic. London, 18 17. Marx; Geschichtlich Darstellung der Giftlehre. Gottingen, 1829. Mata ; Tratado de medicina y cirugia legal. Paris, 1874. Mayercon and Bergeret ; Recherches sur la passage de I'arsenic et de I'antimoine dans les tissus et les humeurs. Paris, 1874. Meissner ; Araometrie in ihrer Anwendung auf Chemie und Technik. Wien, 1816. Mitchell I Falsification of food London, 1848 Mohr ; Chemische Toxilcologie. , Braunschweig, 1874 Mouier ; Memoires sur I'analyse de la lait et des farinas, Paris, 1858. Montgarney ; Essai de toxicologie. Paris, 1818. MuUer ; Anleitung zur Priifung der Kuhmilch. Bern, 1S58. Muuk uud Leyden; Phosphorvergiftung. Berlin, 1865. Neubauer; Chemie des Weines. Wiesbaden, 1S74. Neuman ; Die Erkennung des Bluts bei gerichtlichen Untersuch- ungen. 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 gerichtartliche Bedeutung. Tiibingen, 1875. Or&la ; Rapport sur les moyens de constater la presence de I'arsenic dans les empoisonnements par ce toxique. Paris, 1S41. Ibid ; Trait(? de medicine legale. Paris, 1848. Ibid ; Elements de chimie m^dicale. Paris, 1S51. Ibid; Traite de toxicologie. Paris, 1852. Otto ; Anleitung zur Ausmittelung der Gifte, und zur Erkennung dfer Blutflecken bei gerichtlich-chemischen Untersuchungen. Braunschweig, 1870. Payen ; Substances alimentaires. Paris, 1856. APPENDIX. i6i Fellikeii ; Beitrage zur gerichtlichen Medizin, Toxikologie und Pharmakodynamik. Wiirztburg, 185S. Petit Iiailtte; Instruction simpliiie'e pour la constatation des pro- pri^tees des alt&ations et des falsifications des principales. denrees alimentaires. Bordeaux, 1858. Plaff ; Anleitung zur vornahme gericthlicher Blutuntersuclrungen. Plauen, i860. 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 i- un cours de toxicologic. Paris, 1859. Reyer ; Die Blausaure physiologisch untersucht. Bonn., 186S. Rich; The analyst's annual note-book for 1874. London, 1875. Ritter ; Ueber die Ermittelung von Blut, Samen und Excrementen- fiecken in Kriminalfallen. Wiirztburg, 1854. Ibid ; Beitrage 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 Toxicologic et de m^decine legale appliqu^e a I'empoisonnements. Paris. 1873. Roucher ; Recherches toxicologiques. Paris, 1852. Roussin ; Falsification des vins par I'alun. Paris, 1861. Ryan ; Medical Jurisprudence. London, 1836. Scbmidt ; Ein Beitrag zur Kentniss der milch. Dorpat 1874. Schmidt ; Diagnostik verdachtlicher Flecken. Leipzig, 1848. Schneider ; Die gerichthche Chemie. Wien, 1852. Schroff ; Toxikologische Versuche iiber Arsen. Wien, 1858, Ibid ; Beitrage zur Kentniss des Aconite. Simon; Die Frauenmilch. Berlin, 1838. Sonnenkalb ; L'Aniline et ses couleurs, au point de vue toxicologique. Leipzig, 1864. Sonnenscheiu ; 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. Stows ; A toxicological chart. London, 1872. Tanner; Memoranda on Poisons. London, 1872. Tardieu ; Etude medico-I^gale sur I'empoisonnement. Paris, 1866. Tardieu, Iiorain et Roussin ; Empoisonnement par la strychnine, I'arsenic, et las sals de cuivre. Paris, 1865. i62 LEGAL CHEMISTRY. Tatra; Traite d'empoisonnemeiit par I'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 Verdiinnung und Ver- falschung. Berlin, 1859. Valser; Etud2 sur la recherche, les caracteres distinctifs, et la dosage des alcaloides organiques naturels. Paris, 1862. Verrlois ; Du lait chez la femme dans I'et^t de sante et dans I'etat de maladie. Paris, 1858. Vogel; Eine neue Milchprobe. Stuttgart, i860. ■Walchner; Die Nahrungsmittel des menchens, ihre Verfalschungen und Verunreinigungen. Berlin, 1875. WEilther ; Ueber Erkennung des Arsens bei Arsenvergiftung. Bayreuth, 1854. Wanklyu ; Milk Analysis. London, 1874. ■Wenke ; Das Bier und seine Verfalschung Weimar, i86i. Werber ; Lehrbuch der praktischen Toxikologie. Erlangen, 1870. Wharton and Stille; Medical Jurisprudence. Phila., 1855. Wiokler; Toxikologische Briefe. Weimar, 1852. Wirthgen; Die verschiedenen Methoden zur ermittelung von Blut- flecken in forensischen Fallen. Erlangen, 1861. Witting; Uebersicht der wichtigsten Erfahrungen in der Toxikologie. Hannover, 1827. Wohler 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 m^dicale. Paris, 186S. Zaleivsky; Untersuchung fiber das Conia Dorpat, 1869. MEMOIRS. On poisonM generally and those not elspTrhere clasaifled. Aocum ; Ed. month. Rev. iii, 276 ; Quar. Rev. xxiv, 341 ; Ed. Rev. xviii, 370 Andrews ; Sill Am. Jour. [2] xlvii, 25. Bonis ; Compt rend. Ixxiii. Bunaen ; Ann. Ch. Pharm. cvi, i. Brunner; Archiv. der Pharm, ccii, 4. APPENDIX. 163 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., i860 Joubsrt; Compt. Rend., No. 26. Moitessier ; Annal d'Hygiene, 1868. Orfila ; Mem. de I'acad. roy. de m^d. viii. 493. Otto ; Ann. chem. Pharm. c, 39. Pelliasie ; Jour, de pharm. et de chim., Jan., 1874. Reveil; Compt. Rend. 1.x, 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. Oil the ileHtructiou of organic matter. Brande; Arch. f. Pharm. xlviii, 206. Buchner; N. rept. f. Pharm. xvii, 21. Fresenius ; Zeitsch. f. anal. Chem. 1 Jahrg, 447. Pype; Jour. f. prakt. Chem. Iv, 103. G-raham ; Phil. Mag. [4] xxiii. Llebig; Chem. Centbl. 1857, v. 357. Lud-wig; Arch. f. Pharm. xcvii, p. 23. Schacht; Arch. £. Pharm. l.xxvi, 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, 6S1 ; Compt. Rend. July 7, 1845. Bloxam; Jahresb. f. Chem. i860. 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 Dratjer ; Dingl. poly. Jour. cciv. 385, Elliot and Storer ; Sill. Jour. 32, p. 380. Erlenmeyer; Zeitsch. f. Ch. u Pharm. 1862, 38. Peuchtwanger ; Sill. Jour, xix, 339. Franck; Zeit. f. anal. Chem. iv. 201. 1 64 LEGAL CHEMISTRY. Fresenius ; Arch. f. Pharm. Ixii, 57 ; Ann. der. Chem, u. Pharm. xliii. 361 ; ibid, xlix, 275; Zeits f. anal Chem. vi, 196; ibid ii, 19; ibidi. 483; Qual, Chem. Anal. p. 346. Fresenius u. v. Baho ; Pogg, Anal. vol. xc, t;65 ; Ann. Chem. Pharm. xlix, 287. Fype; Phil. mag. ii 487 ; Jour f. prakt. Chem. Ix. 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. Ixvii, 56. Houzeau ; Ding. poly. Jour. Bd. 207, Heft. 2, 3. Hume ; Phil. Mag. Sept. 1812, 109. Keber; Viertlj. f. gerichtl. Med. ix. 96. Kirsohgassner ; J. f. prakt. Chem. Ixviii. 168; Jahresb. i860, 170. Lippirt ; J. f. prakt. Chem. Ixviii, 168 ; Jahresb., i860, 170. Lois ; Oest, Zeitsch. {. prakt. Heilkunde, xlix, 1859. Mayer; Pharm. Zeitsch. Russ. 2 Jahrgang. Meyer; Ann. Chem. u. Pharm. Ixvi. Montmeja; La France Med., Jan. 8, 1S73. 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. Hose; Pogg. Annal. vol. xc; Zeitsch. f. anal. Chem. i, 410; Chimie Anal. Paris, 1859, p. 405. Roussin; Jahresb. 1866,801. Saikovrski; Arch. f. path. Anat. xxxi, 400. Selmi; Dent. Chem. Gess. Ber. 1872, 477. Schafer ; Jour, f . prakt. Chem. Ixxxii, 286. Schneider; Wien. Akad. Ber. 1851, vi, 409 Sklarek; Arch. f. Anat. u. Phys. i866, 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. XTgers; Ann. Chem. Pharm. clix, 127. Ures ; Diet. Arts, etc., new edit, i, 189. Vitry; Annal d'hygifene publ. xxxvi, 14. Wackenroder ; Arch. f. Pharm. Ixx, 14. Watt's Chem. Diet, i, 365; Supp. 215. Werther; J. pr. Chem. Ixxxii, 235; Jahresb. 1861, 851. Wiggers; Canstatt's Jahresb. der Pharm. 1864. Wittstein; Zeitsch. f. anal. Chem. ii, 19. Wohler; Ann. der Chem. u. Pharm. Ixix, 364; Mineral Analyse, Gottingen, 1861, 213. Wood and Doremus ; N. Y. Med. Press, 1859, 543. APPENDIX. 165 Zeuger; Zeitscli. £. Ch. Pharm. 1862, 38; Jahresb. 1862, 595. Oa the detection of Antiuioity. Bellini; Jhb. f. Pharm. 1868, p. 453. Bottger ; Chem. Centralbl, 3 Jahigang, Buuseu ; Ann. Chem. Pharm. cvi, p. 3. Hofman; Ann. Chem. Pharm. p, 155; Chem. Soc. Quar. J. xiii, 79. Millon and Levaran; Corapt. Rend. 21. Odliug ; Guys Hosp. Rep. [3] ii, 249. Pfaff ; Fogg. Ann. f. Phys xl, 339. Thompson ; Jour. f. prakt. Chem. ii, 369. Vogel ; ibid, xiii, 57. Oa tbe deteetioii of ]Hercury. Buchner; N. rept. f. Pharm. xvii, 272. Erdman and Marchand; Jour f. prakt. Chem. xxxi. Hittdorf ; Pogg. Annal. cvi. Konig; Jour. f. prakt. Chem. Ixx. Mayencon and Bergeret; Jour, de I'Anat. et de la Physiol 1873, No. I ; Jour, de Pharm. et de Chim., Aug., 1873. Schneider; Ber. d. Wien, Akad. d. Wiss. xl. ■Wormley ; Chem. News, ii. No. 43. 0» the detectiou of Pfaosp>ioi>ti.«t. Barrett; Phil. Mag. [4] xxx, 321. Blondlot; Jour. de. Phy. et de Chim. 3 e 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 Neubavter ; Zeitsch. f. Anal. Chem. i, 366, Hager; Zeitsch f. anal. Chem. 1870, 465. Hoffman; Jahresb. 1859, 663. Kle'wer; Pharm. Zeitsch f. Russl., 386. Kohler; Poly, centralh, 1871, 263. Lapeyrere ; La France med., Jan. 4, 1873. Lefort; Jour de Pharm. et de Chim., Aug., 1874. Lispcwitz ; Ann. f. Phys. u. Pharm. cviii, 625. Mistcherllch ; Jour. f. prakt. Chem. Ixvi, 238. Mulder ; Arch. f. d. hoU. Zeit. ii, 4 ; Zeitsch. i. Anal. Chem. ii, 3. Otto ; Zeitsch, f. Chem. [2] ii, 733. Pribram ; Zeitsch, f. anal. Chem. 1871, 109. Hitter; Th&e de doctorat as sciences : Paris, 1872. Scherer; Ann. Ch. Pharm. cxii, 214. 1 66 LEGAL CHEMISTRY. Schieffendecker ; Zeitsch. f. anal. Chem. 1872, iii. Scbom ; Zeitsch. f. anal. Chem. [2] v, 664. Wiggers ; Canstatt's Jahresb. f. Fharm. 1854. On the Barral ; Compt. rend., Ivi, 834. Bastelaer; Chem. Centralb, 1868, 1342. Cailletet; ibid, 1858, 1392. Corput; ibid, i860, 207. Crooks; Chem. News., vol. xxxiii, 73. Danckwort; Archiv der Pharm. [2] xx, 47. Davis; Chem. News, xxv., 207. Bulenberg 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. Rivet ; Ann. de Phys. et de Chim., 36 serie t, xlvii. Eumniel ; 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. 170 LEGAL CHEMISTRY. Ou the exaiuiuatiou of Fatty Oils. Behrens ; Ding. poly. Jour., cxxxi, 50. Calvert; Pharm. J. Trans, xiii, 356. Clarke; Chem. News, xxiii, 145. Dingl; Poly. Jour., clxxiv. Douny; Bull. See. d'Erc, 1S64, 372; Jahresb., 1864, 734. Drageudorff ; Pharm. Zeitsch. f . Russl., ii, 434. Fluckiger; Chem. Centralb, 1871, 55. Glassner ; (trans.) Am. Chem., Dec, 1873. Grobley ; J. Pharm. [3], iv, 285 ; ibid. v. 67. Jacobson; Bull. Soc. Chim., [2] vii, 96. Langlies; Zeitsch. f. anal. Chem., 1870, 534. Lud"wig; Archiv der Pharm., [3] i, i. 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 Diet, of Arts, etc., iii, 300. Vogel ; Chem. Centralbl, 1863, 945. ■Watt's Diet, of Chem., iv., 182. On the cxamiiiatio:! of I?lillc. Boussingault ; Ann. Chem. Phys. [4] xxv, 382. Baurahauer; J. pr. Chem., lx.xxiv, 145. Casselman ; Chem. Centralb, 1S63, 689. Dancer; Chem. News, v, 2ifp. 51. Daubrawa; Jour. f. prakt. Chem., Ixxviii, 426. Donne; Compt. rend., xvii, pp. 585, 591. nihol and Joly ; Wurtz's Diet, 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, bv 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. MuUer; Zeitsch. f. anal. Chem., No. 3, 1872. Otto; Ann. Chem. Pharm., cii, 47. Pelouze and Fremy; Traite' de Chim. gen., [2 edit.] Paris, 181:7 P- 195- APPENDIX. 171 Pribram ; Dings, poly. Jour., cxcvii, 448 Reichelt; Bayr. K. u. Gwbl., 1859, 602. Reineck ; Ding. poly. Jour., cci, 433. Rosenthal; Chem. Centralb, 1S54, 1392. Seely ; Sill. Am. J., vii, 293. Vernois and Becqueret; Ann. d'Hygiene, April, 1853. Voelcker; Am. Chem., May, 1875, P- 4'^- Vogel; Poly. Notizbl., No. 10, 1874. Wanklyn; Pliarra. Viertelj., xx, 201: Milk Jour., 1, 109.160; Chem. News, xxviil. No. 623 ; ibid. No. 736 ; Pharm. Journ. Trans., [3] i, 605. Oil the detection of adulteration iu IViue and Beer. Beck ; Edinb. Phil. Jour., 1835 Bertlaelot and Pleurien ; Compt. rend., Ivii, 394. Blume ; Dings, poly. Jour., clxx, 240. Bolly and Paul ; Manual of Tech. Anal., p. 331. Boyer and Coulet; Compt. rend., Ixxvi, 585. Brande; Phil. Trans, 181 1. Cotlini; Ann. du Genie Civil, No. 3, 1873. Cotliui and Fantazini ; Ann. di Chim. Appl. alia Medi., Juli, 1870. Cbristison; Edinb. Phil. Jour., 1838. Diez; Ann. Ch. Pharm., xcvi, 304. Dudlaux; Ann. de Chim. et de Phys., July and Sept., 1874; Compt. rend. Ixxviii, 11 59. DufBeld; Am. Jour. Pharm., Mar. 1862. Dupre ; Chem. Soc. Jour, xx, 493. Fantenelle ; J. Chim. Me'd., iii, 332. Faure ; J. Pharm,, vii, 200. Fischern; Ann. Chem. Pharm., Iviii, 705. Fresenius ; ibid, Ixiii, 384. Geiger ; Mag. f . Pharm., xix, 266. G-eromont; 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, s^rie, Nov., 1874 ; Compt. rend., Ixxix. 523. Kersting; Ann. Ch. Pharm.. Ixx, 50. Khol; J. Chim. Me'd., [4] ii, 251. Liebig, Poggendorff and Wohler ; Handworterb. ix, 676. Ludersdorf ; J. f. prak. Chem., xxiv, 102, Maisch ; Proc, Am. Pharm. Assn., 1863, 296 • 1864, 291 ; 1866, 267. Mallard ; J. Chim. M^d., iii, 326. Maumene ; Bull. Soc. Chim., xxii. No. i. Miller ; Jour, de Pharm. et de Chim., Mar., 1873. Mitis ; Baierisch. K. u. Gewerbeblatt, 1838. 172 LEGAL CHEMISTRY. Phipson; Zeitsch. f. anal. Chem., ix, 121. Reiman's Farb. Zeit., Nos. 14-15, 1874. Rome! ; Mon. Scien., iii, t. iii, No. 382. Salleron ; Compt. rend., Ixxviii, No. 16. Scheitz; Arch. Pharm., [3] v, 331. Schubert; Pogg. Annal., Ixx, 397. Sestini ; Landwirthsch. Ver. Stat., xv, 9. Tuchschmeidt ; Jahresb., 1871,967. Zierl; Baierisch. Kunst. Gewerbebl, 183& Bias; Viertelj. f. prakt. Pharm., xxi, 584. Bruuner ; 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. £. Pharm,, xxxix. No. i. Dragendorff; Archiv. der Pharm., April and May, 1874; Dhrgs. 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., 2 me sem.. No. 123. Michselis; 111. Gewerbz, 1871, 8. Muspratt's Chem. i, 281. Polil; 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., Ixxxvii, 344. Stolber ; ibid, xciv, iii. Tire's Diet. Chem., 4th edit., 1831, p. 203. Vogel and Hammon's Mitth, i860, 184. Wittstein; Archiv der Pharm., Jan. 1875. On the testing of Vinei^ar. Bussy and Buignet ; Jahresb., 1865, 69. Greville ; Ding. poly. Jour., cxxxi, 139. Liebig, Foggendorff and Wohler ; Handworterb, ii, 867 Mohr; Ann. Ch. Pharm., xxxi, 277. MoUerat; Ann. Chim. Ixviii, 88. Nicholson; Ding. pol. Jour., cxxxix, 441. Otto ; Ann. Chem. Pharm., cii, 69. Roscoe; Chem. Soc. Jour., xv, 270. Runge; Gewz. Bayer. 1871, 4. APPENDIX. i-jT^ Strohl; Jour, de Pharm. et de Chim., Sept., 1874. Toorn; Jour. f. Chem., vi, 171. Wagner; Chem. Tech., (English trans.) p. 467. ■WilUams ; Pharm. J. Trans., xiii, 594. On the detection of adultemtioBis in Snlphate of Quinine. Delondre and Henry ; J. Pharm., [3] xxi, 281. Grmelin'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. £. Chem., J. i, 150; Jahresb. 1862, 619. Phillips; Lond. Lane, i, 820. Riegel ; Jahresb. f. Pharm., xxv, 340. On the detection of Blood Stains. Barruel; Ann. d'Hygifee 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. Brdman ; Jour. pr. Chem., Ixxxv, i ; Jahresb., 1862, 634. Falck ; Ber. Klinisch. Wochb., 1872. van G-euus 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 Iiiebig, Poggendorff and Wohler ; Handworterb, iv, 177. Liman; Jahresb., 1863, 715 Lowe; Pharm. Centralb, 1854, 137. Mandl; Lond. Lane, Dec. 17, 1842, 176. MuUer; Zeitsch. f. anal. Chem., 1872, iii. Orfila; Jour, des Prog& des Sc, iv, 1827; Archiv. gen. de Med., Fev., 1828. Papillon ; Mon. Scien. Ques., Jan., 1874, 59. Reynolds ; Br. Med. Jour., Jan. 4, 1873. Rose; Jahresb. der Pharm., ii, 365; Jahresb., I854, 754. Roussin ; Ann. d'Hyg. et de Med. \i%., 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. 174 LEGAL CHEMISTRY. 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'Hygiene. pub., 1849, No. 43. Renak ; Diagnostisch. u. Pathologisch. Unters. Berhn, 1845, pp. 148, 171. Schmidt ^ Diagnostik Verdach. Feecken, Leipzig, 1848, pp. 42-48- INDEX. Acetic Acid, 49, 89 AcUs, 46, 95 Acetic, 49, 89 Boric, 90 Formic, 89 Hydriodic, go Hydrobromic, 90 Hydrochloric, 46 Hydrocyanic, 50 Hydrofluoric, 88 Hydrosulphunc, gi Nitric, 47, 88 Oxalic, 49, 88, 8g, 95 Phosphoric, 48, 90, 95 Phosphorous, 45 Sulphuric, 47, 89, 95 Aconitine, 79 Alcoholmeter (Gay-Lussac's Alkalies, 52, 93 Ammonia, 50 Baryta, 5+ Lime, 53 Potassa, 53 Soda, 53 Strontia, 54 Alkaloids, 65 Aconitine, 79 Aniline, 75 Aricine, 77 Atropine, 80 139 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 Alkaloidsjseparation of, by Stas's method, 65 Separation of, by Otto's method, 69 Separation of, by v. Uslar and Erdman'a method, 70 ■ Separation of, byRodgers& 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, 75 176 hXDEX. Antimony, 30, 62, 93 Detection of, by Flander & Danger's .•nethod, 32 Detection of, by Naquet's method, 34 Ariciiie, 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 Raspall's test, 29 Detection of, by Reinsch's test, 30 Arsenic, estimation of, 21 Ashes, examination of, 104 Atropine, So B. Barley meal in flour, 117 Baryta, 54. Barreswil's test for milk, 134 Beberine, 76 Bicarbonate of soda in milk, 135 Bismuth, 62 Blood stains, detection of, 144 Bleaching of hair, gS Boric acid. 90 Boutigny's examination of fire-arras, 100 Bromine, 55, 90, 93, 94 Briicke's test for blood stains, 146 Brucine, 7S Buckwheat in flour, 117, 120 C. Cadmium, 63 Carbonate of ilme and magnesia in flour, 1 2 5 Cerebral substances in milk, 136 Chalk in milk, 135 Chlorine, 54 Chromium, 64 Cinchonine in sulphate of quinine, 143 Codeine, So Conine, 75 .Coins, examination of, iia Colchicine, 80 Colza oi), 130 Copper, 62, 63 Corn meal in flour, 117,120 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, 135 F. Fire-arms, examination of, 100 Weapons provided with a flint, 100 Weapons not provided with a flint, 103 Fixed Oils, examination of, 128 Colza, 130 Hempseed, 131 Linseed, 131 Olive, 128 Flander & Danger's test for antimony, 32 Flander & Danger's test for mercury, 37 Food (flour and bread), 114 Examination of the gluten, ji6 Examination of the starch, iiS Examination of the ash, 124 Formic acid, 89 Fresenius & Neubauer's test for phosphorus, Galactoscope, 132 Graham and Hofman's method for alka- loids, 73 Ground bones in bread and flour, 125 Gum arable in milk, 135 Gum tragacanth in milk, 135 H. Hsmin crystals, 144 Hair, examination of, 96 Hempseed oil, 131 Hoppe-Seyler^s test for blood, 145 Hydriodic acid, 90 INDEX. 177 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, 132 Lactometer, 133 Lactoscope, 132 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 oil, 131 Linseed meal in flour, 120 M. Macadam's method for alkaloids, 73 Magnesia, in sulphate of quinine, 142 Mannite in sulphate of quinine, 142 Marchand's test for milk, 133 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, 131 Mineral substances, in flour and bread, 124 In milk, 135 In sulphate of quinine, 142 Mistcherlich's test for phosphorus, 40 Morphine, 80 N. Naquet's test for antimony, 34 Narcotine, 77 Nicotine, 75 Nitric acid, 47, 88 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, S 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, 141 Phosphoric acid, 48, 9o» 95 Phosphorous acid, 45 Phosphorus, 39, 95 Detection of by Orfila's method, 39 Detection of by Mistcherlich's method, 40 Detectionof by Dusart's method, 40 Detection of, by Fresenius and Neubau- ' er's method, 42 Estimation of, 41; Picrotoxine, 80 Plaster in flour, 126 lyS INDEX. 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 mealin flour, 118 Potassa, 53, 93 Prollius' method for alkaloids, 72 Prussic acid, 50 Quinine, 77 Q. R. Raspail's test for arsenic, 29 Reinsch's test for arsenic, 30 Reveil's test for vinegar, 142 Rice meal in flour, 120 Robin's method for spermatic stains, 154 Rodgers and Girdwood's method for alka- loids, 71 Rye meal in flour, 117, 120 S. Salicine in sulphate of quinine, 142 Sand in flour, 125 Silver, 57 Smithson's pile, 36 Soda, 53, 92, 93 Solanine, 79 Spermatic stains, detection of, 152 Spermatozoa, 153 Starch in sulphate of quinine, 142 Stearic acid in sulphate of quinine, 142 Stas's method for alkaloids, 65 Strychnine, 78 Sugar in milk, 136 Sugar in sulphate of quinine, 142 Sulphate of copper in bread, 127 Sulphate of quinidine in sulphate of quinine, 143 Sulphate of quinine, examination of, 142 Sulphuretted hydrogen, gi Sulphuric acid, 47, 89, 95 Sympathetic inks, tests for, 110 T. Tin, 56, 61 U. V. Uslar and Erdman's method for alkaloids, 70 V. Veratrine, 77 Vinegar, examination of, 141 W. Wines, examination of, 136 Writings, examination of, 105 Z. Zinc, 64 SCIENTIFIC BOOKS PUBLISHED BY D. YA]Sr NOSTEAN'D, 23 Murray Street & 27 Warren Street, NEW YORK. Weisbach's Mechanics, Fourth Edition. Revised. 8vo. Cloth. $10.00. A MANUAL OF THEORETICAL MECHANICS. By Julius Weisbach, Ph.D. Translated from the fourth aug- mented and improved German edition, with an introduction to the Calculus, by Bcklet B. Coxe, A.M., Mining Engineer. 1,100 pages, and 903 wood-cut illustrations. Abstract of Contents. — Introduction to the Calculua — The General Principles of Mechanics — Phoronomics, or the Purely Mathematical Theory of Motion — Mechanics, or the General Physical Theory of Motion - Statics of Rigid Bodies — The Application of Statics to Elasticity and Strength — Dynam. ics of Bigid Bodies— Statics of Fluids -Dynamics of Fluids — The Theory of Oscillation, etc. " The present edition ia an entirely new work, greatly extended and very much improved. It forms a text-hook which must find its way into the hands, not only of every student, but of every engineer who desires to refresh his mem- ory or acquire clear ideas on doubtful points.'' — Manufacturer and Builder. " We hope the day is not far distant when a thorough course of study and education as such shall be demanded of the practising engineer, and with this view we are glad to welcome this translation to our tongue and shores of ons of the mo st able of the edu cators of Europe." — TJie Technologist. iWIERTIFIC BOOKS PUBLISIIEB BY Francis' Lowell Hydraulics. Third Edition. 4to. Cloth. $15.00. LOWELL HYDEAULIC EXPEEIMENTS — being a Selec- tion from Experiments on Hydraulic Motors, on the Elow of Water over Weirs, and in Open Canals of Uniform Eectangular Section, made at Lowell, Mass. By J. B. Eeancis, Civil Engineer. Third edition, revised and enlarged, including many New Ex- periments on Gauging Water in Open Canals, and on the Flow through Submerged Orifices and Diverging Tubes. With 23 copperplates, beautifully engraved, and about 100 new pages of text. The work is divided into parts. Pabt I., on hydraulic motors, includes ninety-two experiments on an improved Poumeyron Turbine Water-Wheel, of about two hundred horse-power, with rules and tables for the construction of similar motors ; thirteen experiments on a, model of a centre-vent water- wheel of the most simple design, and thirty-nine experiments on a centre-vent water-wheel of about two hundred and thirty horse-power. Part II. includes seventy-four experiments made for the purpose of deter- mining the form of the formula for computing the flow of water over weirs ; nine experiments ou the effect of back-water on the ilow over weirs; eighty- eight experiments made for the purpose of determining the formula for com- puting the flow over weirs of regular or standard forms, with several tables of comparisons of the new formula with the results obtained by former experi- menters; five experiments on the flow over a dam in which the crest was of the same form as that built by the Essex Company across the Merrimack Kiver at Lawrence, Massachusetts; twenty-one experiments on the effect of observing the depths of water on a weir at different distances from the weir ; an exten- sive series of experiments made for the purpose of determining rules for gauging streams of water in open canals, with tables for facilitating the same ; and one hundred and one experiments on the discharge of water through sub- laerged orifices and diverging tubes, the whole being fully illustrated by twenty-three double plates engraved on copper. In 1855 the proprietors of the Locks and Canals on Merrimack River con- sented to the publication of the first edition of this work, which contained a fleleotion of the most important hydraulic experiments made at Lowell up to that time. In this edition the principal hydraulic experiments made there, subsequent to 1855, have be^u added, including the important series above mentioned, for determining rules for the gauging the flow of water in open oauals, and the interesting series on the flow through a submerged Venturi's tube, in which a larger flow was obtair.ed_than_anv wo find recorded. D. VAN NOSTRAND. Williamson's Meteorological Tables. 4to. Flexible Cloth. $3.50. PEACTICAL TABLES IN METEOEOLOGY AND HYPSO- METEY, in connection with the use of the Barometer. By Col. E. S. W1LLIA.MSON, U. S. A. Merrill's Iron Truss Bridges. Third Edition. 4to. Cloth. $5.00. ffiON TEUSS BEIDGES FOE EAILEOADS. 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A TREATISE ON THE STRENGTH OF BRIDGES AND ROOFS — comprising the determination of Algebraic formulas for Strains in Horizontal, Inclined or Rafter, Triangular, Bow- string, Lenticular and other Trusses, from fixed and moving loads, with practical applications and examples, for the use of Students and Engineers. By Saiitjei. H. Shreve, A.M., Civil Engineer. " On the whole, Mr. Shreve has produced a hook which is the simplest, clearest, a,nd at the same time, the most systematic and with the best math- ematical reasoning of any work upon the same subject in the language." — Railroad Gazette. " From the unusually clear language iii which Mr. Shreve has given every statement, the student will have but himself to blame if he does not become thorough ma^ster of the subject." — London Mining Journal. " Mr. Shreve has produced a work that must always take high rank as a text-book, * * * and no Bridge Engineer should be without it, as a valuable work of reference, and one that will frequently assist him out of difficulties." — Franklin Institute Journal. The Kansas City Bridge. 4to. Clotli. $6.00 WITH AN ACCOUNT OF THE REGIMEN OF THE MIS- SOURI RIVER, and a description of the Methods used for Founding in that River. By 0. Chanuie, Chief Engineer, and Geoegb Moeisoh", Assistant Engineer. Illustrated with five lithographic views and twelve plates of plans. Illustrations. VrEWS. — View of the Kansas City Bridge, August 5J, 1869. Lowering Caisson No. 1 into position. Caisson for Pier No. 4 brought into position. View of Foundation Works, Pier No. 4. Pier No. 1. Plates. — I. Map showing location of Bridge. II. Water Record — Cross Section of River — Profile of Crossing tion Works, Pier No. 3. IV. Founda- tion Works, Pier No. 4. V. Founda- tion Works, Pier No. 4. VI. 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An enlarged and improved edition of the Author's origiaal work. By S. Whipple, C. E., Inventor of the Whipple Bridges, &o. Second Edition. The design has been to develop from Fmidamental Principles a system easy of comprehension, and such as to enable the attentive reader and student to judo-e understandingly for himself, as to the relative merits of different plans and combinations, and to adopt for use such as may be most suitable for the cases he may have to deal with. It is hoped the work may prove an appropriate Text-Book upon the subject treated of, for the Engineering Student, and a useful manual for the Practic- ing Engineer and Bridge Builder. 6 HGIENTIFIC BOOK& FUBLI8EED BY Stoney on Strains. Nmv and Mevised Edition, with numerous illustrations. Eoyal 8vo, 664 pp. Cloth. $13.50. THE THEOEY OF STRAINS IN GIEDEES and Similar Struc- tures, with Observations on the Application of Theory to Practke, and Tables of Strength and other Properties of Materials. By BnfDO» B. Signet, B. 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AMEEICAN AND EUEOPEAN EAILWAY PEACTICE, in the Economical Generation of Steam, including the materials and construction of Coal-burning Boilers, Combustion, the Varia- ble Blast, Vaporization, Circulation, Super-heating, Supplying and Heating Feed-water, &c., and the adaptation of Wood and Coke-buming Engines to Coal-burning ; and in Permanent Way, including Eoad-bed, Sleepers, Bails, Joint Fastenings, Street Eailways, &c., &c. By Alexandee L. Holley, B. P. With 77 lithographed plates. " This is an elaborate treatise by one of our ablest civil engineers, on the con- struction and use of locomotives, with a few chapters on the building of Rail- rocsds. * * * All these subjects are treated by the author, who is i first-class railroad engineer, in both an intelligent and intelligible manner. Tho facts and ideas are well arranged, and presented in a clear and simple style, accompanied by beautiful engravings, and we presume the work will be regard' ed as indispensable by all who are interested in a knowledge of the construc- tion of railroads and rolling stock, or the working of locomotives." — Scieniifie America, 8 SCIE]SrTIFIC BOOKS PUBLISHED BY Henrici's Skeleton Structures. 8vo. Cloth, fl.50. ' SKELETON STEUCTUEES, especially in their AppUcation to the biiilding of Steel and Iron Bridges. By Olatjs Henkici. With folding plates and diagrams. By presenting these general examinations on Skeleton Structures, Tvith particular application for Suspended Bridges, to Engiaeers, I Tenture to ex- press the hope that they "will receive these theoretical results with some confi- dence, even although an opportunity is •wanting to compare them with practi- cal results. 0. H. Useful Information for Railway Men. Pocket form. Morocco, gilt, $2.00. Compiled by W. G. Hamilton, Engineer. 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Contents. — Report on Filtration — London "Works, General — Chelsea Water 'Works and Filters — Lambeth "Water "Works and Filters — Southwark and "Vauxhall "Water "Works and Filters — Grand Junction "Water "Works and Filters — "West Middlesex "Water "Works and Filters — New Eiver "Water "Works and Filters — East London Water Works and Filters— Leicester Water Works and Filters — York Water Works and Filters — Liverpool Water Works and Filters — Edinburgh Water Works and Filters — DubUn Water Works and Filters — Perth Water Works and Filtering Gallery — Berlin Water Works and Filters — Hamburg Water Works and Eeservoirs — Altona Water Works and Filters — Tours Water Works and Filtering Canal — Angers Water Works and Filtering Galleries — Nantes Water Works and Filters — Lyons Water Works and Filtering Galleries — Toiilouse Water Works and Filtering Galleries — Marseilles Water Works and Filters — Genoa Water Works and Filtering Galleries — Leghorn Water Works and Cisterns — Wakefield Water Works and Filters — Appendix. Tnnner on Roll-Turning. 1 vol. 8vo. and 1 vol. plates. $10.00. A TEEATISE ON EOLL-TUENING EOE THE MANUFAC- TUEE OF lEON. By Petee Tttnitee. Translated and adapted. By John B. Peasse, of the Pennsylvania Steel Works. With numerous wood-cuts, 8vo., together with a folio atlas of 10 litho- graphed plates of Eolls, Measureraents, &c. " We commend this book as a clear, elaborate, and practical treatise upon the department of iron manufacturing operations to ■which it is devoted. The writer states in his preface, that for twenty-five years he has felt the necessity of such a work, and has evidently brought to its preparation the fruits of experience, a, painstaking regard for accuracy of statement, and a desire to furnish information in a style readily understood. The book should be in the hands of every one interested, either in the general practice of mechanical engineering, or the special branch of manufacturing operations to which the wo«ieTsl!sta|((ifc_-=4-»»'' 10 SCIENTIJ^'HJ BOOKS PUBLISHED BY Jacob on Storage Reservoirs. 18mo. Boards 50 cts. THE DESIGNING AND CONSTEUOTION OP STOKAGE EESEKVOIKS. By Akthue Jacob, B. A. With tables and wood-cuts representing sections, etc. HewTson on Embankments. 8to. Cloth. $3.00. PEINCIPLES AND PEACTICE OF EMBANKING LANDS from River Eloods, as applied to the Levees of the Mississippi. By William Hewson, Civil Engineer. " This is a valuable treatise on the principles and preictioe of embanking lands from river floods, as applied to the Levees of the Mississippi, by a highly- intelligent and experienced engineer. The author says it is a first attempt to reduce to order and to rule the design, execution, and measurement of the Levees of the Mississippi. 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Link and Valve Motions, by W. S. Auohincloss. Sixth Edition, 8vo. Cloth. $3.00. APPLICATION OF THE SLIDE VALVE and Link Motion to Stationary, Portable, Locomotive and Marine Engines, with new and simple methods for proportioning the parts. By William S. AucHiNCLOss, Civil and Mechanical Engineer. Designed as a hand-book for Mechanical Engineers, Master Mechanics, Draughtsmen and Students of Steam Engineering. All dimen- sions of the valve are found with the greatest ease by means of a Printed Scale, and proportions of the Unk determined without the assistance of a model. Illustrated by 37 wood-cuts and 21 lithographic plates, together with a copperplate engraving of the Travel Scale. All the matters we have mentioned are treated with a clearness and absence of unneoesaary verbiage which renders the work a peculiarly valuable one. The Travel Scale only requires to be known to be appreciated. Mr. A. writes so ably on his subject, we wish he had written more. London En- gineerinff. We have never opened a work relating to steam which seemed to us better calculated to give an intelligent mind a clear understanding of the depart' ment it discusses. — Scientific American. 12 SCIENTIFIC BOOKlS I'OBLISHJEJI' Ji x Slide Yalve by Eccentrics, by Prof. C. W. MacOord. 4to. lUustrated. Cloth, $4.00. A PEACTICAL TEEATISE ON THE SLIDE VALYE BY ECCENTRICS, examining by metliods, the action of the Eccen- tric upon the Slide Valve, and explaining the practical proces- ses of laying out the movements, adapting the valve for its various duties in the steam-engine. Eor the use of Engineers, Draughtsmen, Machinists, and Students of valve motions in general. By 0. "W. MacCoed, A. M., Professor of Mechanical Drawing, Stevens' Institute of Technology, Hoboken, N J. Stillman's Steam-Engine Indicator. 13mo. Cloth, $1.00. THE STEAM-ENGINE INDICATOR, and the Improved Mano- meter Steam and Vacuum Gauges ; their utility and application. By Paul Stillman. New edition. 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Engineer Department, No. 9, containing Eeports of numerous experiments conducted in New York City, during the years 1858 to 1861, inclusive. By Q- A. UiLL-MOiiE, Lt.-Gol. U. S. Corps of Engineers, Brevet Major-Geiioral U. S. Army. With numerous illustrations. " This ■work containg a record of certain experiments and researches made under the authority of the Engineer Bureau of the War Department from 1858 to 1861, upon the various hydraulic cements of the United States, and the materials for their manufacture. The experiments were carefully made, and are -well reported and compiled. ' — Journal Franklin Institute. Gillmore's Ooignet Beton. 8vo. Cloth. $3.50. COIGNET BETON AND OTHEE AETIPICIAL STONE. By Q. A. GiLLMOEE, Lt.-Col. U. S Corps of Engineers, Brevet Major-General U. S. Army. 9 Plates, Views, etc. This ■work describes ■with considerable minuteness of detail the several kinds of artificial stone in most general use in Europe and no^w beginning to be introduced in the United States, discusses their properties, relative merits, and cost, and describes the materials of ■which they are composed. The subject is one of special and growing interest, and we commend the work, embodying as it does the matured opinions of an experienced engineer and expert. Gillmore on Roads. 13mo. Cloth. In Press. A PEACTICAL TREATISE ON THE CONSTEUCTION OF EOADS, STEEETS; AND PAVEMENTS. By Q. A. 14 SCIENTIFIC BOOKS PUBLISHED BT Williamson on the Barometer. 4to. ClQtli. $15.00. ON THE USE OP THE BAEOMETEB, ON SURVEYS AND EE00NNAI8SAN0ES. Part I. Meteorology in its Connec- tion with Hypsometry. Part II. Barometric Hypsometry. By E. S. WiLLiAMsoir, Bvt. Lieut.-Ool. U. S. A., Major Corps of Engineers. With. Illustrative Tables and" Engravings. Paper No. 15, Professional Papers, Corps of Engineers. " Sah Fkakcisco, Cal., Feb. 27, 1867. " Gten. A. A. HuMPHBBTS, Chief of Engineers, U. S. Army : " GBNEEAli, — I have the honor to submit to you, in the foUowing pages, the results of my iuvestigations in meteorology and hypsometry, made with the view of ascertaining how far the barometer can be used as a reliable instru- ment for determining altitudes on extended lines of survey and reconnais- sances. These investigations have occupied the leisure permitted me from my professional duties during the last ten years, and I hope the results ■will be deemed of suf&cient value to have a place assigned them among the printed professional papers of the United States Corps of Engineers. " Very respectfully, your obedient servant, "R. S. WILLIAMSON, " Bvt. Lt.-Col. tr. S. A., Major Corps of IT. S. Engineers." Yon Cotta's Ore Deposits. 8vo. aoth. $4.00. TREATISE ON OEE DEPOSITS. By Beenhaed Ton Ootia, Professor of Geology in tlie Poyal School of Mines, Preidberg, Saxony. Translated from the second German edition, by Peedeeick Peime, Jr., Mining Engineer, and revised by the author, vdth Humerous illustrations. " Prof. Von Cotta of the Ereiberg School of Mines, is the author of the best modem treatise on ore deposits, and we are heartily glad that this ad- mirable work has been translated and published in this country. The trans- lator, Mr. Frederick Prime, Jr., a graduate of Freiberg, has had in his work the great advantage of a revision by the author himself, who declares in a prefatory note that this may be considered as a new edition (the third) of his own book. " It is a timely and welcome contribution to the literature of mining in this country, and we are grateful to the translator for his enterprise and good judgment in undertaking its preparation ; while we recognize with equal cor- diality the liberality of the author in granting both permission and assist- vosi&.''''—ExWact from Beview in Engineering and Mining Journal. 7). VAN JSrOSTUAJSTD. 15 Plattner's Blow-Pipe Analysis. Second edition. Bevised. 8vo. Cloth. $7.50. PLATTNEE'8 MANUAL OP QUALITATIVE AJSTD QUAN- TITATIVE ANALYSIS WITH THE BLOW-PIPE. Prom the last German editioa Revised and enlarged. By Prof. Th. EiCHTEK, of th.e Eoyal Saxon Mining Academy. Translated by Prof. H. B. CoENWALL, Assistant in the Columbia School of Mines, New York ; assisted by Johs- H. Caswell. Illustrated with eighty-seven wood-cuts and one Lithographic Plate. 560 pages. " Plattner's celebrated work has long been recognized as the only complete book on BloTT-Pipe Analysis. The fourth Grerman edition, edited by Prof, Kichter, fully sustains the reputation -vrhioh the earlier editions acquired dur- ing the lifetime of the author, and it is o, source of great satisfaction to ub to know that Prof. Eichter has co-operated with the translator in issuing the American edition of the work, which is in fact a fifth edition of the original work, being far more complete than the last G-erman edition." — Silliman's Journal. There is nothing so complete to be found in the English language. Platt- ner's book is not a mere pocket edition ; it is intended as a comprehensive guide to all that is at present known on the blow-pipe, and as such is really indis- pensable to teachers and advanced pupils. " Mr. Cornwall's edition is something more than a translation, as it contains many corrections, emendations and additions not to be found in the original. It is a decided improvement on the work in its German dress." — Journal of Applied Chemigiry. Egleston's Mineralogy. 8vo. Illustrated with 34 Lithographic Plates. Cloth. $4.50. LECTURES ON DESOEIPTIVE MINEEALOGY, Delivered at the School of Mines, Columbia CoUege. Bt Peopessob T. Egleston". These lectures are what their title indicates, the lectures on Mineralogy delivered at the School of Miues of Columbia College. They have been printed for the students, in order that more time might be given to the vari- ous methods of examining and determining minerals. The second part has only been printed. The first part, comprising crystallography and physical mineralogy, will be printed at some future time. 16 SCIENTIFIC BOOKS PUBLISHED BY Pynchon's Chemical Physics. Neiv Edition. Revised and Enlarged. Crown 8vo. Cloth. |3.00. INTEODUCTION TO CHEMICAL PHYSICS, Designed for the Use of Academies, Colleges, and High Schools. Illiistrated with numerous engravings, and containing copious experiments with directions foi' preparing them. By Thomas Ettggles Pynchoh", M.A., Professor of Chemistry and the Natural Sciences, Trinity College, Hartford. Hitherto, no -wort suitable for general use, treating of all these subjects "within the limits of a single volume, could be found ; consequently the atten- tion they have received has not been at all proportionate to their importance. It is believed that a book containing so much valuable information within so small a compass, cannot fail to meet with a, ready sale among all intelligent persons, while Professional men. Physicians, Medical Students, Photograph- ers, Telegraphers, Engineers, and Artisans generally, will find it specially valuable, if not nearly indispensable, as a book of reference. " "We strongly recommend this able treatise to our readers as the first work ever published on the subject free from perplexing technicalities. In style it is pure, in description graphic, and its typographical appearance is artistic. It is altogether a most excellent work." — EclecUo Medical Jowrnal. " It treats fully of Photography, Telegraphy, Steam Engines, and the various applications of Electricity. In short, it ia a carefully prepared volume, abreast with the latest scientific discoveries and inventions." — Hart- ford Gourant. Plympton's Blow-Pipe Analysis. 13mo. Cloth. $1 50. THE BLOW-PIPE : A Guide to Its Use in the Determination of Salts and Minerals. Compiled from various sources, by George W. Plympton, C.E., A.M., Professor of Physical Science in the Polytechnic Institute, Brooklyn, N. Y. " This manual probably has no superior in the English language as a text- book for beginners, or as a guide to the student working without a teacher. To the latter many illustrations of the utensils and apparatus required in using the blow-pipe, as well as the fully illustrated description of the blow- pipe flame, will be especially serviceable." — New York Teacliei: 27. VAWWOSTRAJS^D. Dubois' Graphical Statics. 8vo. eOflUustrations. Cloth. $2 00. THE NEW METHOD OP GEAPHICAL STATICS. Bj A. J. Dubois, C.E., Ph.D. G-ases in Coal Mines. 18mo. Boarids. 50 cts. A PRACTICAL TREATISE ON THE GASES MET WITH IN" COAL MINES. By the late J. J. Atkinson", Govern- ment Inspector of Mines for the County of Durham, England. "Watt's Dictionary of Chemistry. Supplementary Volume. 8vo. Cloth. $9.00. This volnin© Tarings the E.eoord of Chemical Discovery down to the end of the year 1869, inclnding also several additions to, and corrections of, former results which have appeared in 1870 and 1871. *^,* Complete Sets of the Work, New and Kevised edition, intsludiag above supplement. 6 vols. 8vo. Cloth. $62.00. Rammelslberg's Chemical Analysis. 8vo. Cloth. $2.25. GUIDE TO A COTJESE OF QUANTITATIVE CHEMICAL ANALYSIS, ESPECIALLY OF MINERALS AND FUR- NACE PRODUCTS. niustrated by Examples. By C. F. iiAMMELSBEEG. Translated by J. Towlee, M.D. This work has been translated, and is now published expressly for those students in chemistry whose time and other studies in colleges do not permit them to enter upon the more elaborate and expensive treatises of Presenius and others. It is the condensed labor of a master in chemistry and of a prac- tical analyst. 18 SCIE]SrTIFIC BOOKS PUBLISHED BY Eliot and Storer's Qualitative Olieniical Analysis. Neiv Edition, Revised, ISmo. lUustrated. Cloth. $1.50. A COMPEKDIOTTS MANUAIi OF QUALITATIVE CHEMI- CAL AJSTALYSIS. By Chakles W. Eliot and EeankH. Stoeek. Eevised with the Cooperation of the Authors, hy "William Eip- LET Nichols, Professor of Chemistry in the Massachusetts Insti- tute of Technology. " This Manual has great merits as a practical introduction to the science and the art of -which it treats. It containa enough of the theory and practioo of qualitatiTe analysis, " in the wet -way," to bring- out all the reasoning in- volved in the science, and to present clearly to the student the most approved methods of the art. It is specially axlapted for exercises and experiments in the lahoratory; and yet its classifications and manner of treatment are so systematic and logical throughout, as to adapt it in a high degree to that higher class of students generally -who desire an accurate knowledge of tha practical methods of arriving at scientific facts." — Lutheran Observer. " We -wish every academical class in the land could have the benefit of the fifty exercises of two hours each necessary to master this hook. Chemistry -would cease to be a mere matter of memory, and become a pleasant experi- mental and intellectual recreation. We heartily commend this little volume to the notice of those teachers -who believe in using -the sciences as means of mental discipline." — College Gourani. Craig's Decimal System. Square 33ino. Limp. 50o. WEIGtHTS AND MEASURES. An Account of the Decimal System, -with Tables of Conversion for Commercial and Scientific Uses. By B. E. Oeaig, M. D. " The most lucid, accurate, and useful of all the hand-books on this subject that -we have yet seen. It gives forty-seven tables of comparison bet-ween the English and Trench denominations of length, area, capacity, weight, and the Centigrade and Fahrenheit thermometers, with clear instructions how to use them ; and to this practical portion, which helps to make the transition as easy as possible, is prefixed a scientific explanation of the errors in the metric system, and how they may be corrected in the laboratory." — Nation. U. VAiY XOSTEAjSTD. 19 Nugent on Optics. 12mo. 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" It is the best summary of the arguments in favor of the metric -weights and measures -with which we are acquainted, not only because it contains in small space the leading facts of the case, but because it puts the advocacy of that system .on the only tenable grounds, namely, the great convenience of a decimal notation of weight and measure as well as money, the value of inter- national uniformity in the matter, and the fact that this metric system is adopted aui in general use by the majority of civilized nations." — The Nation- Butler on Ventilation. 18mo. Boards. 50 cts. VENTILATION OF BUILDINGS. By W. F. Butlee. Illustrated. " As death by insensible suffocation is one of the prominent causes which BweU our bills of mortality, we commend this book to the attention of philan- thropists as well as to architects. " — Boston Globe. 20 SCIEATTIFIC BOOKS PUBLISHED BY Harrison's Mechanic's Tool-Book. 13mo. Cloth. $1.50. MECHANIC'S TOOL BOOK, with practical rules and suggestions, for the use of Maciiinists, Iron Workers, and others. By "W. B. Haeeison, Associate liditor of the " American Artisan." Illustra- ted with 44 engravings. " This ■work is specially adapted to meet the wants of Machinists and -work- ers in iron generally. It is made up of the work-day experience of an intelli- gent and ingenious mechanic, who had the faculty of adapting tools to Tarions purposes. The practicability of his plans and suggestions are made apparent even to the unpractised eye by a series of well-executed wood engravings." — PTiUadelpMa Inguirerr. Pope's Modern Practice of the Elec- tric Telegraph. Ninth Eaition. 8vo. Cloth $3.00. A Hand-book for Electricians and Operators. By Fiunk L. Pope. Seventh edition. Eevised and enlarged, and fully illustrated. Extract from Letter of Prof. Morse. " I have had time only cursorily to examine its contents, but this examina^ tion has resulted in great gratification, especially at the fairness and unpre- judiced tone of your whole work. " Tour illustrated diagrams are admirable and beautifully executed. " I think all your instructions in the use of the telegraph apparatus judi- cious and correct, and I most cordially wish you success." Extract from Letter of Prof. O. W. Sough, of the Dudley Oisercatsry. " There is no other work of this kind in the English language .that con- tains in so small a compass so much practical information in the application of galvanic electricity to telegraphy. It should be in the hands of every one interested in telegraphy, or the use of Batteries for other purposes." Morse's Telegraphic Apparatus. Illustrated. 8vo. Cloth. |3.00. EXAMINATION OE THE TELEGRAPHIC APPARATUS AND THE PROCESSES IN TELEGAPHY. By Samuel E. B. MoBSE, LL.D., United States Commissioner Paris Universal Exposition, 1867. i>. VAN Nostra NB. 21 Sabine's History of the Telegraph. ISmo. Cloth. $1.25. HISTOEY AND PEOGEESS OF THE ELECTEIO TELE- GEAPH, -with. Descriptions of some of the Apparatus. By EoBBRi SA.Bii>rB, C. E. Second edition, with additions. Contents. — I. Early Observations of Electrical Phenomena. II. Tele- graphs by Frictional Electricity. III. Telegraphs by Voltaic Electricity. IV. Telegraphs by Electro-Magnetism and Magneto-Electricity. V. Tele- graphs noTV in use. VI. Overhead Lines. VII. Submarine Telegraph Lines. Vm. Underground Telegraphs. IX. Atmospheric Electricity. Haskins' Galvanometer. Pocket form. Illustrated. Morocco tucks. $3.00. THE GALVAlvTOMETER, AND ITS USES; a Manual for Electricians and Students. By C. H. Haskins. " We hope this excellent little work will meet with the sale its merits entitle it to. To every telegrapher who ownsj or uses a Galvanometer, or ever expects to, it will be quite indispensable." — The Tdegraphen: CuUey's Hand-Book of Telegraphy. 8vo. Cloth. $5.00. A HAND-BOOK OF PRACTICAL TELEGRAPHY. By E. S. Gullet, Engineer to the Electric and International Telegraph Company. Fifth edition, revised and enlarged. Foster's Submarine Blasting. 4to. Cloth. $3.50. SUBMAEINE BLASTING in Boston Harbor, Massachusetts — Eemoval of Tower and Corwin Eoeks. By John G. Fosteb, Lieutenant-Colonel of Engineers, and Brevet Major- General, U. S. Army. Illustrated with seven plates. List of Plates. — 1. Sketch of the Narrows, Boston Harbor. 2. Townsend's Submarine Drilling Machine, and "Working Vessel attending. 3. Submarine Drilling Machine employed. 4. Details of Drilling Machine employed. 5. Cartridges and Tamping used. 6. Fuses and Insulated "Wires used. 7. Portable Friction Battery used. 22 HCIENTIFIG BOOKS PUBLISHED BY Barnes' Siibmarine "Warfare. 8to. Cloth. 15.00. SUBMAEINE WAEFAEE, DEFENSIVE AND OFFENSIVE. Comprising a full and complete History of tlie Invention of the Torpedo, its employment in War and results of its use. De- scriptions of tlie Tarious forms of Torpedoes, Submarine Batteries and Torpedo Boats actually used in War. Methods of Ignition by Machinery, Contact Fuzes, and Electricity, and a full account of experiments made to determine the Explosive Force of Gun- powder under Water. Also a discussion of the Offensive Torpedo system, its effect upon Iron-Clad Ship systems, and influence upon Future Naval Wars. By Lieut. -Commander Johb- S. Baenes, U. S. N. With twenty lithographic plates and many wood-cuts. " A book important to military men, and especially so to engineers and ar- tillerists. It consists of an examination of tlie varions offensive and defensive engines tKat have been contrived for submarine hostilities, including a discuB- siou of the torpedo system, its effects upon iron-clad ship-systems, and its probable influence upon future naval wars. PlateS of a valuable character accompany the treatise, which affords a useful history of the momentous sub- ject it discusses. A great deal of useful information is collected in its pages, especially concerning the inventions of Scholl and Verdtt, and of Jones' and Hunt's batteries, as ^611 as of other similar machines, and the use in submarine operations of gun-cotton and nitro-glycerine." — N. Y. Times. Randall's Quartz Operator's Hand- Book. 12mo. Cloth. $2.00. QUARTZ OPEEATOE'S HAND-BOOK. By P. M. Eandall, New edition, revised and enlarged. Fully illustrated. The object of this work has been to present a clear and comprehensive ex- position of mineral veins, and the means and modes chiefly employed for the mining and working of their ores — more especially those containing gold and rilver. D. VAN" JSrOSTRAJSTD. 23 McOulloch's Theory of Heat. 8vo. Cloth. In Press. AN BLEMBNTAEY TEEATISE OK THE MECHANI- CAL THEORY OE HEAT, AND ITS APPLICATION TO AIR AND STEAM ENGINES. By Prof. R. S. Mc- CULLOCH. Benet's Ohronosoope. Second Edition. mustrated. 4to. Cloth. $3.00. ELECTEO-BALLISTIO MACHINES, and the Schtiltz Ohrono- scope. By Lieutenant-Colonel S. V. Benet, Captain of Ordnance, U. S. Army. Contents. — 1. Ballistio Pendulum. 2. Gun Pendulum. 3. Use of Elec- tricity. 4. Navez' Maoliine. 5. Vignotti's Machine, with Plates. 6. Benton's Electro-Ballistic Pendulum, -with Plates. 7. Leur's Tro-Pendulum Machine 8. Sohultz's Ohronosoope, with t-wo Plates. Michaelis' Chronograph. 4to. Illustrated. Cloth. $3.00. THE LE B0ULENG1& CHRONOGRAPH. With three Htho- graphed folding plates of illustrations. By Brevet Captain E. MiCHAELis, Eirst Lieutenant Ordnance Corps, U. S. Army. " The excellent monograph of Captain Miohaelis enters minutely into the details of construction and management, and gives tables of the times of flight calculated upon a given fall of the chronometer for all distances. Captain Michaelis has done good service in presenting this work to his brother officers, describing, as it does, an instrument -which bids fair to be in constant use in •xir future ballistic experiments.' —Army and Navy JouttuS, ■2-i SCIENTIFIC BOOKS PUBLISHED BY Silversmith's Hand-Book. Fourth Edition. Illustrated. 13mo. ClotK $3.00. A PEACTICAL HAND-BOOK TOE, MINEES, Metallurgists, and Assayers, comprising th.e most recent improvements in the disintegration, amalgamation, smelting, and parting of the Precious Ores, with a Comprehensive Digest of the Mining Laws. Greatly augmented, revised, and corrected. By Julius SiLVEKSMiTH. Fourth edition. Profusely illustrated. 1 vol. 12mo. Cloth. $3.00. One of the most important features of this -work is that in which the metallurgy of the precious metals is treated of. In it the author has endeav- ored to embody all the processes for the reduction and manipulation of the precious ores heretofore successfully employed in Germany, England, Mexico, and the United States, together with such as have been more recently invented, and not yet fully tested — all of which are profusely illustrated and easy of comprehension. Simms' Levelling. 8vo. Cloth. $3.50. A TEEATISE ON THE PEINCIPLES AND PEACTICE OE LEVELLING, showing its application to purposes of Eailway Engineering and the Construction of Eoads, &c. By Eeedeeick W. Simms, C. E. Erom the fifth London edition, revised and corrected, with the addition of Mr. Law's Practical Examples for Setting Out Eailway Curves. Illustrated with three lithographic plates and numerous wood-outs. " One of the most important text-books for the general stirveyor, and there is scarcely a question connected with levelling for which a solution would be sought, but that would be satisfactorily answered by consulting this voliune." — Mining Journal. " The text-book on levelling in most of our engineering schools and col- leges." — Engineers. "The publishers have rendered a substantial service to the profession, especially to the younger members, by bringing out the present edition of Mr. Simms' useful work." — Engineering. D. VAN NOSTIiAN'D. 25 Stuart's Successful Engineer. 18mo. Boards. 50 cents. HOW TO BECOME A SUOCESSPUL ENGINEER: Being Hints to Youths intending to adopt the Profession. By BEE;srAED Stuakt, Engineer. Sixth Edition. •■ A valuable little book of sound, sensible advice to young men wlio wisli to rise in the most important of tlie professions." — Beieniifia American. Stuart's Naval Dry Docks. T'wenty-four engraTings on steel. Fourth Edition. 4to. Cloth. $6.00. THE NAVAL DRY DOCKS OF THE UNITED STATES. By Ohasles B. STtrAni. Engineer in Chief of the United States Navy. List of Illustrations. Pumping Engine and Pumps — Plan of Dry Dock and Pmnp-WeU — Sec- tions of Dry Dock — Engine House — ^Iron Floating Gate — Details of Floating Gate— Iron Turning Gate — Plan of Turning Gate — Culvert Gate — Filling Culvert Gates — Engine Bed — Plate, Pumps, and Culvert — Engine House Roof — Floating Sectional Dock — Details of Section, and Plan of Turn-Tables — Plan of Basin and Marine Railways — Plan of Sliding Frame, and Elevation of Pumps — Hydraulic Cylinder — ^Plan of Gearing for Pumps and End Floats — Perspective View of Dock, Basin, and Railway — Plan of Ba^in of Ports- mouth. Dry Dock — Floating Balance Dock — Elevation of Trusses and the Mar ohinery — Perspective View of Balance Dry Dock Free Hand Drawing. Profusely Illustrated. 18mo. Boards. 50 cents. A GUIDE TO ORNAMENTAL, Figure, and Landscape Draw- ing. By an Art Student. Contents. — Materials employed in Drawing, and how to use them — On Lines and how to Draw them — On Shading — Concerning lines and shading, with applications of them to simple elementary subjects — Sketches from Na- ture. 26 SCIENTIFIC BOOKS PUBLISHED BY Minifie's Mechanical Drawing. Ninth 'Edition. Boyal 8vo. Caoth. $400. A TEXT-BOOK OP GEOMETEICAL DRAWING for the use of Mechanics and Schools, in w^hich 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 technicahties are avoided as much as possible. With illustrations for Drawing Plans, Sections, and Elevations of Buildings and Machinery ; an Introduction to Isometrical Draw- ing, and an Essay on Linear Perspective and Shadows. Illus- trated with over 200 diagrams engraved on steel. By Wm, MiNiriB, Architect. Eighth Edition. With an Appendix on the Theory and Application of Colors. " It is the best ■work on Drawing tliat ■we tave ever seen, and is especially a text-book of Greometrioal Drawing for the use of Mechanics and Schools. No young Mechanic, such aa a Machinist, Engineer, Cabinet-Maker, MUl^wright, or Carpenter, should be without it." — Scientific American. " One of the most comprehensive works of the kind ever published, and can- not but possess great value to builders. The style is at once elegant and sub- stantial." — Pennsylvania Inquirer. " Whatever is said is rendered perfectly intelligible by remarkably well- executed diagrams on steel, lea^nng nothing for mere vague supposition ; and the addition of an introduction to isometrical dra^wing, linear perspective, and the projection of shadows, winding up with a useful index to technical terms.'' — Glasgow Mechanics' Journal. 1^" The British Government haa authorized the use of this book in their schools of art at Somerset House, London, and throughout the kingdom. Minifie's G-eometrical Drawing. New Edition. Enlarged. 13mo. Cloth. $2.00. GEOMETRICAL DRAWING. Abridged from the octavo edition, for the use of Schools. Illustrated with 48 steel plates. New edition, enlarged. " It is well adapted as a text-book of drawing to be used in our High Schools and Academies where this ■useful branch of the fine arts has been hitherto too much neglected." — Boston Journal. D. VAJSr JTOSTJiAJ^J). 27 Bell on Iron Smelting. 8vo. Cloth. $6.00. CHEMICAL PHENOMENA OF lEON SMELTZNG. An ex- perimental and practical examination of the circumstances wliich determine the capacity of tlie Blast Furnace, the Temperature of the Air, and the Proper Condition of the Materials to be operated upon. By I. Lowthian Beix. Battershall's Legal Chemistry. Illustrated. 13mo. Cloth. In press. LEGAL CHEMISTEY. A Guide to the detection of Poisons, Falsification of Writings, Adulteration of Alimentary and Pharmaceutical Substances ; Analysis of Ashes, and Examina- tion of Hair, Coins, Fire-Arms, and Stains, as applied to Chemical Jurisprudence. For the use of Chemists, Physi- cians, Lawyers, Pharmacists, and Experts. Translated with 'additions, including a list of books and - memoirs on Toxi- cology, etc., from the French of A. Na QUET. By J. P. Bat- TERSHALL, Ph.D., with a Preface by C. F. Chandlee, Ph.D., M.D., LL.D. King's Notes on Steam. Nineteenth Edition. 8vo. Cloth. $3.00. LESSONS AND PEACTIOAL NOTES ON STEAM, the St^am- Engine, Propellers, &c., &c., for Young Engiueers, Students, and others. By the late W. E. Ejng, U. 8. N. Eevised by Chief- Engineer J. W. King, U. S. Navy. " This is one of the beat, because eminently plain and practical treatises on the Steam Engine ever published.' — Philadelphia Press. This is the thirteenth edition of a valuable -work of the late W. H. King, XJ. S. N. It contains lessons and practical notes on Steam and the Steam En- gine, Propellers, etc. It is calculated to be of great use to young marine en- gineers, students, and others. The text is illustrated and explained by nu- merous diagrams and representations of machinery. —JSostore Daily Adver- tiser. Text-book at the U. S. Naval Academy, Annapolis. 28 SCIENTIFIC BOOKS PUBLISHED BY Burgh's Modern Marine Engineering. One tMok 4to vol. Cloth. $25.00. HaU morocMO. $30.00. MODEEN MAEINE ENGINEERING, appUed to Paddle and Screw Propulsion. Consisting of 36 Colored Plates, 259 Practical Wood-cut Illustrations, and 403 pages of Descriptive Matter, tlio ■whole being an exposition of the present practice of the follow- ing firms : Messrs. J. Penn & Sons ; Messrs. Maudslay, Sons & Pield ; Messrs. James Watt & Co. ; Messrs. J. & G. Eennie ; Messrs. P. Napier & Sons ; Messrs. J. & W. Dudgeon ; Messrs. Eavenhill & Hodgson ; Messrs. Humphreys & Tenant ; Mr. J. T. Spencer, and Messrs. Porrester & Co. By N. P. Bubgh, Engineer. Pkincipai, Contents. — G-eneral Arrangements of Engines, 11 examples — G-eneral Arrangement of Boilers, 14 examples — General Arrangement of Superheaters, 11 examples — Details of Oscillating Paddle Engines, 34 ex- amples—Condensers for Screw Engines, botli Injection and Surface, 20 ex- amples — Details of Screw Engines, 20 examples — Cylinders and Details of Screw Engines, 21 examples — Slide Valves and Details, 7 examples — Slide Valve, Link Motion, 7 examples — Expansion Valves and Gear, 10 exam.- ples — Details in General, 30 examples— Screw Propeller and Pittings, 13 ex- amples Engine and Boiler Eittings, 28 examples - In relation to the Princi- ples of the Marine Engine and Boiler, 33 examples. Notices of the Press. "Every conceivable detail of the Marine Engine, under aU its various forms, is profusely, and we must add, admirably illustrated by a. m.ultitude of engravings, selected from the best and most m.odern practice of the first Marine Engineers of the day. The chapter on Condensers is peculiarly valu- able. In one word, there is no other work in existence which will bear a moment's comparison with it as an exponent of the skill, talent and practical experience to which is due the splendid reputation enjoyed by many British Marine Engineers." — iSn^mcc?'. " This very comprehensive work, which was issued in Monthly parts, has just been completed. It contains large and full drawings and copious de- scriptions of most of the best examples of Modern Marine Engines, and it is a complete theoretical and practical treatise on the subject of Marine Engi- neering." — American Artisan. This is the only edition of th{) above work ivith the beautifully colored plates, and it is out of print in England. I). VAN NOSTRAND. 29 Bourne's Treatise on the Steam En gine. Ninth Edition. Illustrated. 4to. Cloth. |15.00. TEEATISE ON THE STEAM ENGINE in its various appUoa, tions to Mines, Mills, Steam Navigation, Rail-ways, and Agricul. ture, with the theoretical investigations respecting the MotivQ Power of Heat and the proper Proportions of Steam Engines. Elaborate Tables of the right dimensions of every part, and Practical Instructions for the Manufacture and Management of every species of Engine in actual use. By JoHif Bouehe, being the ninth edition of "A Treatise on the Steam Engine," by ■flie "Artisan Club." Illustrated by thirty-eight plates and five hundred and forty-sis wood-cuts. As Mr. Bourne's ■work has the great merit of avoiding unsound and imma- ture views, it may safely be consulted by all who are really desirous of ac- quiring trustworthy information on the subject of which it treats. During the twenty-two years which have elapsed from the issue of the first edition, the iniprovem.ents introduced in the construction of the steam engine have been both numerous and important, and of these Mr. Bourne has taken care to point out the more prominent, and to furnish the reader with such infor- mation as shall enable him readily to judge of their relative value. This edi- tion has been thoroughly modernized, and made to accord with the opinions and practice of the more successful engineers of the present day. All that the book professes to give is given with ability and evident care. The scien- tific principles which are permanent are admirably explained, and reference is made to many of the more valuable of the recently introduced engines. 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By the late J. J. Atkinsok, Government Inspector of Mines for the County of Durham, England. 14. FRICTION OF AIR IN MINES. By J. J. Atkinson, author of "A Practical Treatise on the Gases met with in Coal-Mines." IS. SKEW ARCHES. By Prof. E. W. Hyde, C.E. Illustrated with numerous engraTings and three folded plates. 16. A GRAPHIC METHOD FOR SOLVING CERTAIN AL- GEBRAIC EQUATIONS. By Prof. George L. Vose. With illustrations. 17. WATER AND WATER SUPPLY. By Prof. W. H. Cor- FiELD, M.A., of the University College, London. 18. SEWERAGE AND SEWAGE UTILIZATION. By Prof. W. H. CoftEiELD, M.A., of the University College, London. 19. STRENGTH OP BEAMS UNDER TRANSVERSE LOADS. By Prof. W. Allan, author of " Theory of Arches." With illustrations. 20. BRIDGE AND TUNNEL CENTRES. By John B. McMastebs, O.E. With illustrations. 21. SAFETY-VALVES. By Richard H. Buel, C.E. With Illustrations.