PART IX.—INORGANIC POISONS. (continued 2)

Muscles, 1

Liver, 10 ·8

Brain, 36 ·5

Spinal Marrow, 37 ·3

But Ludwig’s[771] experiments and conclusions are entirely opposed to this, since both in acute and chronic cases he found as follows (per cent. As₂O₃):—

Brain, ·0002

Liver, ·001

Kidney, ·0004

Muscle, ·00025

So that he detected in the liver five times more than in the brain. M. P. Hamberg has also confirmed the fact, that more is found in the liver and kidneys than in the nervous tissues.

Chittenden[772] found in a body the following quantities of arsenic estimated as arsenious acid:—

Grain.

Stomach and gullet, 0·158

Intestines, 0·314

Liver, 0·218

Kidney, 0·029

Lungs and spleen, 0·172

Heart, 0·112

Brain, 0·075

Diaphragm, 0·010

The whole arsenic present was estimated as equal to 3·1 grains of arsenious acid, viz., 2·628 grains absorbed, and 0·472 unabsorbed; of the absorbed portion 8·3 per cent. was found in the liver.

With regard to the preliminary treatment of the stomach and fluids submitted to the analyst, the careful noting of appearances, the decantation, washing, and examination[773] (microscopical and chemical) of any deposit, are precautions so obviously dictated by common sense, that they need only be alluded to in passing. Of some considerable moment is the question which may be put to the analyst in court, in reference to the possible entrance of arsenic into the living body, by accidental and, so to speak, subtle means. Such are the inhaling of the fumes from the burning of arsenical candles,[774] and of emanations from papers (see p. 541),[775] as well as the possible entrance of arsenic into the body after death from various sources, such as arsenical earth, &c.[776]

§ 741. Imbibition of Arsenic after Death.—The arguments which are likely to be used, in favour of a corpse having become arsenical may be gathered from a case related by Sonnenschein:—Certain bodies were exhumed in two churchyards; the evidence went to show that they had been poisoned by arsenic, and this substance was actually found in the bodies, while at the same time it was discovered to exist also in traces in the earth of the churchyard. The theory for the defence was, that although the arsenic in the earth was in an insoluble state, yet that it might combine with lime as an arsenite of lime; this arsenite would become soluble by the action of carbonic acid set free by vegetation, and filter down to the corpse. Sonnenschein suspended a quantity of this earth in water, and passed CO₂ through it for twelve hours; on filtering, the liquid gave no evidence of arsenic. A similar result was obtained when an artificial mixture of 1 grm. of arsenious acid and 1 pound of earth were submitted to the same process.

The fact would appear to stand thus: oxide of iron in ordinary earth retains arsenic, and requires treatment with a concentrated acid to dissolve it. It therefore follows that, if a defence of arsenical earth is likely to be set up, and the analyst finds that by mere extraction of the tissues by water he can detect arsenic, the defence is in all probability unsound. The expert should, of course, deal with this question on its merits, and without prejudice. According to Eulenberg,[777] in arsenical earth—if, after having been crushed and washed, it lies for some time exposed to the disintegrating action of the air—soluble arsenical salts are formed, which may find their way into brooks and supplies of drinking water. We may infer that it is hardly probable (except under very peculiar circumstances) for a corpse to be contaminated internally with an estimable quantity of arsenic from the traces of arsenic met with in a few churchyards.

It occasionally happens that an exhumation is ordered a very long time after death, when no organs or parts (save the bones) are to be distinguished. In the case of a man long dead, the widow confessing that she had administered poison, the bones were analysed by Sonnenschein, and a small quantity of arsenic found. Conièrbe and Orfila have both asserted that arsenic is a normal constituent of the bones—a statement which has been repeatedly disproved. Sonnenschein relates:[778]—“I procured from a churchyard of this place (Berlin) the remnants of the body of a person killed twenty-five years previously, and investigated several others in a similar way, without finding the least trace of arsenic. Similar experiments in great number were repeated in my laboratory, but in no case was arsenic recognised.” The opinion of the expert, should he find arsenic in the bones, must be formed from the amount discovered, and other circumstances.

A difficult case on which to form an opinion is one recorded by William P. Mason,[779] as follows:—

The deceased, a farmer, bachelor, sixty-five years of age, and in good health, was taken violently sick shortly after breakfast, with vomiting and distress in the stomach. Although a physician was summoned, the symptoms increased in severity, and a little after midnight death ensued. The funeral took place three days later. Certain very damaging pieces of circumstantial evidence having been collected, the housekeeper was arrested on the charge of murder, it having been shown, among other things, that on the day preceding the death she had purchased an ounce of white arsenic.

Thirty-five days after death (from March 20 to April 25) the body was exhumed, and found in a state of remarkable preservation, and free from cadaveric smell. The stomach presented evidences of inflammation.

Portions sent for analysis were the stomach, portion of intestine, portion of liver, one kidney, and the heart. Arsenic was found in all these parts. White octahedral crystals were found in the contents of the stomach, which on separation gave arsenical reaction.

The arsenic found was:—

Stomach and intestine, 0·2376 grm.

Liver and kidney, 0·0032 „

Heart, 0·0007 „

Total as metallic arsenic, 0·2415 „

The amount of arsenic recovered and produced in court was in quantity sufficient to produce death. Some time after the analytical report was made to the coroner, it was learned that an embalming fluid, highly arsenical in character, had been used upon the body by the undertaker at the time of preparation for burial. No injection of this embalming fluid was practised, but cloths wrung out in the fluid were laid upon the face and chest, and were kept constantly wet therewith during a period of many hours. In all about two quarts of embalming fluid were so used. Its composition appeared to be a strongly acidified solution of sodium arsenite and zinc sulphate. Only the arsenic and zinc were determined quantitatively, and they were found to be, zinc (metallic), 1·978 per cent., and arsenic (metallic), 1·365 per cent. by weight. An amount of this fluid measuring 15·7 c.c. would thus contain a weight of arsenic equal to that actually recovered from the body.

Extended medical testimony was offered by the prosecution, tending to show that, under the given circumstances, no fluid of any kind could have reached the stomach through the nose or mouth after death, thus anticipating what the defence afterwards claimed, that the undertaker was responsible for the arsenic discovered in the remains.

In order to gather further light upon the possibility of cadaveric imbibition of embalming fluid through the unbroken skin, test was made for zinc in the heart and stomach, and distinct traces of the metal were found in each instance. That at least a portion of the arsenic found in the body was due to post-mortem causes was thus distinctly proven. A weighed portion (62 grms.) of the stomach and contents was then most carefully analysed quantitatively for both zinc and arsenic with the following results:—Arsenic, 0·0648 grm., and zinc, 0·0079 grm. Bearing in mind the relative quantities of the two metals in the embalming fluid, it will be seen that the arsenic found in the 62 grms. of the stomach was nearly twelve times larger than it should have been to have balanced the zinc which was also present. This fact, together with the discovery of crystals of white arsenic in the stomach, constituted the case for the prosecution, so far as the chemical evidence was concerned.

The defence made an unsuccessful effort to show that the crystals of the tri-oxide originated from the spontaneous evaporation of the embalming fluid. The prosecution met this point by proving that such fluid had been abundantly experimented upon by exposure to a very low temperature during an interval of several months, and also by spontaneous evaporation with a view of testing that very question, and that the results had in every case been negative. Special importance was given these experiments, because of the well-known separation of octahedral crystals during the spontaneous evaporation of a hydrochloric acid solution of the white oxide, it having also appeared that, in the manufacture of the embalming fluid, the arsenic was used as white arsenic.

A very strong point was finally raised for the defence by the inability of the expert on the side of the prosecution to state positively whether or not an embalming fluid of the above composition would diffuse as a whole through dead tissue, or its several parts would be imbibed at different rates of speed, the zinc portion becoming arrested by albuminoid material and being therefore outstripped by the arsenic, or vice versa. The prisoner was ultimately acquitted.

In a case which occurred in the Western States of America, there was good reason for believing that arsenic had been introduced into the corpse of a man after his decease. With regard to the imbibition of arsenic thus introduced, Orfila[780] says:—“I have often introduced into the stomach (as well as the rectum) of the corpses of men and dogs 2 to 3 grms. of arsenious acid, dissolved in from 400 to 500 grms. of water, and have examined the different viscera at the end of eight, ten, or twenty days. Constantly I have recognised the effects of cadaveric imbibition. Sections of the liver or other organs which touch the digestive canal, carefully cut and analysed, furnished arsenic, which could not be obtained sensibly (or not at all) from sections which had not been in contact with this canal. If the corpse remained long on the back after arsenious acid had been introduced into the stomach, I could obtain this metal from the left half of the diaphragm and from the inferior lobe of the left lung, whilst I did not obtain it from other portions of the diaphragm nor from the right lung.” Dr. Reece has also made some experiments on the imbibition of arsenic after death. He injected solutions of arsenious acid into the stomach of various warm-blooded animals, and found at various periods arsenic, not alone in the intestinal canal, but also in the spleen, liver, and kidneys.

§ 742. Analysis of Wall-Paper for Arsenic.—The separation of arsenic from paper admits of great variety of manipulation. A quick special method is as follows:—The paper is saturated with chlorate of potash solution, dried, set on fire in a suitable plate, and instantly covered with a bell-glass. The ash is collected, pulverised, and exhausted with cold water, which has previously thoroughly cleansed the plate and bell-glass; the arsenic in combination with the potash is dissolved, whilst oxides of chromium, copper, aluminium, tin, and lead remain in the insoluble portion.[781]

Fresenius and Hintz[782] have elaborated a method for the examination of wall-papers, fabrics, yarns, and similar substances, which, provided the reagents are pure, is accurate and easy. Twenty-five grms. of the substance are placed in a half-litre distilling flask or retort, and 250 c.c. of HCl, specific gravity 1·19, added; after digestion for an hour, 5 c.c. of a saturated solution of ferrous chloride are added, and the liquid slowly distilled until frothing stops any farther distillation. A further quantity of 100 c.c. HCl is then added, and distilled over. The receiver, in each case, contains water, and must be kept cool. The united distillates are diluted to 800 c.c. and saturated with SH₂. The arsenious sulphide is collected on an asbestos filter. After partial washing, it is heated with bromine in HCl of 1·9 specific gravity, and the solution again distilled with ferrous chloride. The distillate, on now being treated with SH₂, gives arsenious sulphide free from organic matter.

§ 743. Estimation of Arsenic.—Most of the methods for the quantitative determination of arsenic are also excellent tests for its presence. It may be regarded, indeed, as an axiom in legal chemistry, that the precise amount of every substance detected, if it can be weighed or estimated by any process whatever, should be accurately stated. Indefinite expressions, such as “a small quantity was found,” “traces were detected,” &c., are most objectionable. The more perfect of the methods of evolving arsenic can be made quantitative. For example, the galvanic process introduced by Bloxam may be utilised as follows:—A fractional part of the arsenical solution is taken for the experiment; the bottom of a narrow-necked bottle of about 100 c.c. capacity is removed, and replaced by a piece of vegetable parchment. The neck of the bottle carries a cork, which is pierced by (1) a platinum wire, which is attached to a platinum electrode; (2) a short tube, bent at right angles, and connected by piping with a longer tube, which has also a rectangular bend, and dips into a solution of silver nitrate; (3) an ordinary funnel-tube, reaching nearly to the bottom. The bottle is placed in a beaker of such a size as to leave a small interval between the two, and the whole apparatus stands in a large vessel of cold water. Dilute sulphuric acid is now put into the bottle, and also into the beaker, so that the fluid reaches exactly the same level in each. The positive platinum electrode of a battery of six of Grove’s cells, or other efficient combination, is immersed in the liquid outside the bottle, connection with the negative plate is established, and hydrogen very soon comes off, and passes over into the nitrate of silver solution. When all the air is expelled, a portion of the rectangular tube is heated to redness, and if there is no stain nor any reduction of the silver, the acid is pure. If the gas is passed for a long time into the silver solution, the silver will be reduced to some extent by the hydrogen, although arsenic-free;[783] so that it is better to rely upon the metallic ring or stain, which is certain to be formed on heating a portion of the tube red-hot, and keeping it at that temperature for at least ten minutes. The liquid is then passed through the funnel in successive portions; if arsenic is present, there will be a decided metallic ring on heating the tube as before, and if antimony is present, there will also be a stain; the distinctions between these stains have been described at p. 557.

The tube is kept red-hot until the stain is very distinct; then the source of heat is removed, and the gas allowed to bubble through the argentic nitrate solution, which it decomposes, as before detailed (p. 526). This process is continued until, on placing the delivery tube in a sample of clear nitrate of silver solution, there is no darkening of colour. In certain cases this may take a long time, but the apparatus, once set to work, requires little superintendence. At the conclusion, the whole of the arsenic is separated,—part is in the silver solution as arsenious acid, part in the tube as a ring of metallic arsenic. The portion of the tube containing the metallic arsenic should be cut off with a file and weighed, the arsenic then removed and re-weighed; the loss is the metal approximately. Or, the weight of the film may be estimated by having a set of similar deposits of known weight or quantities, in tubes exactly corresponding to those used in the analysis, and comparing or matching them.

The arsenious acid in the nitrate of silver may be dealt with in several ways. The equation given (p. 526) shows clearly that pure arsine, passed into nitrate of silver solution, decomposes it in such a manner that, if either the silver deposited or the free acid is estimated, the quantity of arsenic can from such data be deduced. In operating on organic liquids, ammonia and other products may be given off, rendering either of the indirect processes inadvisable. A very convenient method, applicable in many cases, is to throw out the silver by hydrochloric acid, alkalise the filtrate by bicarbonate of soda, and titrate with iodine solution. The latter is made by dissolving exactly 12·7 grms. of pure dry iodine by the aid of 18 grms. of potassic iodide in one litre of water, observing that the solution must take place in the cold, without the application of heat. The principle of the titration is, that arsenious acid, in the presence of water and free alkali, is converted into arsenic acid—

As₂O₃ + 4I + 2Na₂O = As₂O₅ + 4NaI.

The end of the reaction is known by adding a little starch-paste to the solution; as soon as a blue colour appears, the process is finished.

Another convenient way by which (in very dilute solutions of arsenious acid) the arsenic may be determined, is a colorimetric method, which depends on the fact that sulphuretted hydrogen, when arsenious acid is present in small quantity, produces no precipitate at first, but a yellow colour, proportionate to the amount of arsenic present. The silver solution containing arsenious acid is freed from silver by hydrochloric acid; a measured quantity of saturated SH₂ water is added to a fractional and, if necessary, diluted portion, in a Nessler cylinder or colorimetric apparatus, and the colour produced exactly imitated, by the aid of a dilute solution of arsenious acid, added from a burette to a similar quantity of SH₂ water in another cylinder, the fluid being acidified with HCl.

§ 744. Destruction of the Organic Matter by Nitric Acid, and Subsequent Reduction of the Arsenic Acid to Arsine (Arseniuretted Hydrogen), and final Estimation as Metallic Arsenic.—This process, which is essentially a combination of several, has been much improved in its details by R. H. Chittenden and H. H. Donaldson.[784] 100 grms. of the suspected matters, cut up into small pieces, are heated in a porcelain dish of suitable size, stirred by means of a glass rod with 23 c.c. of pure concentrated nitric acid, and heated up to from 150° to 160°. When the matters assume a yellow or orange colour, the bath is removed from the source of heat, and 3 c.c. of pure concentrated sulphuric acid added, and the mixture stirred, when the mass becomes brown, swells up, and evolves dense nitrous and other fumes. The vessel is again heated to 180°, and while hot 8 c.c. of pure concentrated nitric acid are added, drop by drop, with continual stirring. After this addition, it is heated to 200° for fifteen minutes, and the result on cooling is a hard carbonaceous residue wholly free from nitric acid. The arsenic is in this way oxidised into arsenic acid, which is easily soluble in water. The contents of the dish are, therefore, perfectly extracted by boiling water, the aqueous extract filtered, and evaporated to dryness. The next process is to obtain the arsenic in a metallic state:—

The flask, a Bunsen’s wash-bottle of 200 c.c. capacity, is provided with a small separating funnel of 65 c.c. capacity, with glass stop-cock. This is a very material aid to the obtaining of a slow and even evolution of gas, an important desideratum when all loss is to be avoided; for with only a funnel tube, every time a small portion of fluid is added, a sudden rush of gas takes place, with probably a small, but still more or less appreciable, loss. But the separating funnel, filled with the acid mixture, can be so arranged as to give a constant and regular supply of fluid at the rate of two or three drops per minute, more or less. The gas generated is dried by a calcic chloride tube, and then passes through a tube of hard glass, heated to a red heat by a miniature furnace of three Bunsen lamps with spread burners, so that a continuous flame of 6 inches is obtained, and with a proper length of cooled tube not a trace of arsenic passes by. The glass tube where heated is wound with a strip of wire gauze, both ends being supported upon the edges of the lamp frame, so that the tube does not sink down when heated. The small furnace is provided with two appropriate side pieces of sheet metal, so that a steady flame is always obtained. When the quantity of arsenic is very small, the tube is naturally so placed that the mirror is deposited in the narrow portion; but when the arsenic is present to the extent of 0·005 grm., the tube should be 6 mm. in inner diameter, and so arranged that fully 2 inches of this large tube are between the flame and the narrow portion. When the quantity of arsenic is less, the tube can naturally be smaller.

Acids of different strengths are made as follows:—

Acid No. 1.

545 c.c. pure conc. H₂SO₄.

5000 c.c. H₂O.

Acid No. 2.

109 c.c. pure conc. H₂SO₄.

1640 c.c. Acid No. 1.

Acid No. 3.

218 c.c. pure conc. H₂SO₄.

1640 c.c. Acid No. 1.

Acid No. 4.

530 c.c. pure conc. H₂SO₄.

1248 c.c. H₂O.

25 to 35 grms. of granulated zinc, previously alloyed with a small quantity of platinum, are placed in the generator, and everything being in position, the apparatus is filled with hydrogen by the use of a small quantity of acid No. 2. After a sufficient time has elapsed, the gas is lighted at the jet, and the glass tube heated to a bright redness.

The arsenical solution in concentrated form is mixed with 45 c.c. of acid No. 2, and the mixture passed into the separating funnel, from which it is allowed to flow into the generator at such a rate that the entire fluid is introduced in one hour or one and a half; 40 c.c. of acid No. 3 are then added and allowed to flow slowly into the generator, and, lastly, 45 c.c. of acid No. 4. The amount of time required will vary with the amount of arsenic: 2 to 3 mgrms. of arsenic will require about two to three hours for the entire decomposition, while 4 to 5 mgrms. will need perhaps three to four hours. Where the amount of arsenic is small, only 25 grms. of zinc are needed, and but 45 c.c. of acid No. 2, 30 c.c. of acid No. 3, and 30 c.c. of acid No. 4; but when 4 to 5 mgrms. of arsenic are present, it is better to take the first mentioned quantities of zinc and acids.

The arsenic being thus collected as a large or small mirror of metal, the tube is cut at a safe distance from the mirror, so that a tube of perhaps 2 to 6 grms. weight is obtained. This is carefully weighed, and then the arsenic removed by simple heating; or, if the arsenic is to be saved (as in a toxicological case), dissolved out with strong nitric acid. The tube is then cleaned, dried, and again weighed, the difference giving the weight of metallic arsenic, from which, by a simple calculation, the amount of arsenious oxide can be obtained. Some test results are given as follows; they were obtained by introducing definite quantities of arsenious oxide in the form of a solution mixed with 45 c.c. of No. 2 acid, &c.:—

Quantity of Arsenic introduced. Wt. of Metallic Arsenic found. Theoretical Wt. of Metallic Arsenic.

0·005 grm. As₂O₃ 0·00373 0·00378

0·005 „ „ 0·00370 0·00378

0·004 „ „ 0·00300 0·00303

0·002 „ „ 0·00151 0·00151

Sanger estimates and tests for minute quantities of arsenic by the Marsh-Berzelius process, and uses a generator of hydrogen; that is to say, the hydrogen is evolved in the ordinary way from zinc and sulphuric acid, and the issuing gas dried by calcic chloride; but into this flask is also delivered from another flask, charged with sulphuric acid and zinc, pure hydrogen, so that into the second flask, little by little, may be added the solution to be tested; and, owing to the generating flask, the gas may be made to give a uniform current, and at the end of the operation all arsine swept out. To estimate the quantities of arsenic in the gas, the reduction tube is heated, and a mirror or mirrors obtained, and compared with a set of standard mirrors. The standard mirrors are made as follows:—One grm. of arsenious oxide, purified by repeated sublimation, is dissolved with the aid of a little sodic bicarbonate, and, after acidification with dilute sulphuric acid, made up to 1 litre. This standard solution contains 1 mgrm. of As₂O₃ in every c.c., and is used to make a second standard solution, containing 0·01 mgrm., to every c.c., by diluting 10 c.c. to a litre. Of this last solution, 1 c.c., 2 c.c., 3 c.c., and so on, are measured and introduced into the reduction flask, and the standard mirrors obtained. It is recommended, for obvious reasons, to make more than one standard for each quantity, for the appearance of the mirrors from the same amount of arsenic varies. The tubes are hermetically sealed, and, when not in use, kept in the dark.

This process is convenient for small amounts of arsenic; but, as stated before, the results are given as metallic arsenic, whereas the films appear never to be composed of pure metallic arsenic, but a mixture of hydride and suboxide. Test experiments give, however, fair results.[785]

§ 745. Arsine Developed from an Alkaline Solution.—Fleitmann discovered in 1851 that arsenic, mixed with finely divided zinc, and excess of soda or potash added, evolved arsine; but no stibine was evolved under the same conditions. In 1873 J. W. Gatehouse suggested the use of aluminium and sodic hydrate as a modification of Fleitmann’s test, for the purpose of distinguishing between arsenic and antimony; and this is now the usual process adopted. The hydrogen comes off regularly even in the cold, but it is best to apply a little heat. This test will evolve arsine from arsenious acid, and also from arsenic trisulphide; but it is not available for the detection of arsenic, when the arsenic is in the form of arsenic acid. According to Clark,[786] it is not adapted for quantitative purposes, because, owing to the formation of solid hydride, about one-fifth remains behind.

E. W. Davy, in 1876, proposed the use of sodium amalgam for the generation of arsine; on the whole, it is, however, not so convenient as the aluminium process.

The liquid to be tested is made strongly alkaline with pure sodic or potassic hydrate placed in a flask connected with a tube dipping into a 4 per cent. solution of silver nitrate, a few pieces of sheet aluminium added, and the flask gently heated; any arsine present will reduce the silver. The silver solution thus blackened may be treated in the manner described (p. 567).

§ 746. Precipitation as Tersulphide.—Despite the advantages of some of the processes described, which are (to a certain extent) easy and accurate, not a few chemists still prefer the old method of precipitation with hydric sulphide SH₂, because, although tedious, it has stood the test of experience. If this be used, it is well in most cases to pass sulphurous anhydride through the liquid until it smells strongly of the gas, for by this means any arsenic acid present is reduced, the sulphurous anhydride is quickly got rid of by a current of carbonic anhydride, and then the liquid is saturated with hydric sulphide. In the ordinary way, much time is often wasted in saturating the liquid with this gas. Those, however, who have large laboratories, and daily employ hydric sulphide, possess (or should possess) a water saturated with the gas under pressure; such a liquid, added in equal volume to an arsenical solution, is able to convert the whole of the arsenic into sulphide in a very few minutes. Those who do not possess this hydric sulphide water can saturate in an hour the liquid to be tested, by passing the gas in under pressure.[787] A convenient method is to evolve SH₂ from sulphide of antimony and ClH; the gas passes first into a wash-bottle, and then into a strong flask containing the solution under trial. This flask is furnished with a safety-valve, proportioned to the strength of the apparatus; the two tubes dipping into the wash-bottle and the last flask are provided with Bunsen’s valves, which only allow the gas to pass in one direction. The hydric sulphide is then driven over by heat, and when sufficient gas has in this way passed into the liquid, the flame is withdrawn, and the apparatus allowed to stand for some hours, the valves preventing any backward flow of the liquid or gas. When the precipitate has settled to the bottom, the supernatant fluid is carefully passed through a filter, and the precipitate washed by decantation in the flask, without transference to the filter, if it can be avoided.

The impure sulphide is washed with water, then with alcohol, then with carbon disulphide, then, after having got rid of the lead, again with alcohol, and finally with water; it is then dissolved in ammonia, the ammonia solution filtered, and the filtrate evaporated to dryness on a sand-bath, at a somewhat high temperature; in this way it is freed from sulphur and, to a great extent, from organic matter; after weighing, it may be purified or identified by some of the following methods:—

(a) Solution in Ammonia and Estimation by Iodine.[788]—The filter is pierced, the sulphide washed into a flask by ammonia water (which need not be concentrated), and dissolved by warming, filtered from any insoluble matter, and estimated by iodine and starch.

(b) Oxidation of the Sulphide and Precipitation as Ammonia Magnesian Arseniate, or Magnesia Pyro-Arseniate.—The tersulphide, as before, is dissolved in ammonia (not omitting the filter-paper, which should be soaked in this reagent), the solution filtered, and evaporated to dryness. The dry residue is now oxidised by fuming nitric acid, taking care to protect the dish with a large watch-glass (or other cover) during the first violent action; the dish is then heated in the water-bath until all the sulphur has disappeared, and only a small bulk of the liquid remains; it is then diluted and precipitated by “magnesia mixture.”[789] The fluid must stand for several hours, and, if the arsenic is to be determined as the usual ammoniacal salt, it must be passed through a weighed filter, and washed with a little ammoniacal water (1 : 3). The solubility of the precipitate is considerable, and for every 16 c.c. of the filtrate (not the washings) 1 mgrm. must be allowed. The precipitate, dried at 100°, 2(NH₄MgAsO₄)H₂O, represents 39·47 per cent. metallic arsenic.

The solubility of the magnesium arseniate itself, and the general dislike which chemists have to weighing in such hygroscopic material as a filter, are, perhaps, the main reasons for the variation of this old method, which has lately come into notice. Rose proposed some time ago the conversion of the double salt into the pyro-arseniate—a method condemned by Fresenius and Parnell, but examined and pronounced a practicable and accurate process by Remol, Rammelsberg, Thorpe, Fuller, Wittstein, Emerson, Macivor, Wood, and Brauner. The modification of Rose’s process, recommended by Wood,[790] and still further improved by Brauner,[791] may be accepted.

The precipitation is effected by magnesia mixture, with the addition of half its bulk of alcohol. The solution is allowed to stand for several hours, until it is possible to decant the clear liquid from the precipitate; the latter is now dissolved in ClH, reprecipitated as before, thrown on a small filter, and washed with a mixture of one volume of ammonia, two volumes of alcohol, and three of water.

The precipitate is now dried, and transferred as completely as possible from the filter into a small porcelain crucible, included in a larger one made of platinum, moistened with nitric acid, covered and heated at first gently, lastly to a bright redness; the filter is then treated similarly, and the crucible with its contents weighed. Pyro-arseniate of arsenic (Mg₂As₂O₇) contains 48·29 per cent. of metallic arsenic.

(c) Conversion of the Trisulphide of Arsenic into the Arsenomolybdate of Ammonia.—The purified sulphide is oxidised by nitric acid, the acid solution is rendered alkaline by ammonia, and then precipitated by a molybdenum solution, made as follows:—100 grms. of molybdic acid are dissolved in 150 c.c. of ordinary ammonia and 80 of water; this solution is poured drop by drop into 500 c.c. of pure nitric acid and 300 c.c. of water; it is allowed to settle, and, if necessary, filtered. The molybdic solution must be mixed in excess with the liquid under treatment, the temperature raised to 70° or 80°, and nitric acid added in excess until a yellow coloration appears; the liquid is then passed through a tared filter, and dried at 100°. It contains 5·1 per cent. of arsenic acid [3·3 As].[792]

(d) Conversion of the Sulphide into Metallic Arsenic.—If there should be any doubt as to the nature of the precipitated substances, the very best way of resolving this doubt is to reduce the sulphide to metal; the easiest method of proving this is to dissolve in potash and obtain arsine by the action of aluminium; or if it is desired to evolve arsine from an acid solution with zinc in the usual way, then by dissolving a slight excess of zinc oxide in potash or soda, and dissolving in this the arsenic sulphide; the zinc combines with all the sulphur, and converts the sulpharsenite into arsenite; the zinc sulphide is filtered off, and the filtrate acidified and introduced into Marsh’s apparatus. The original process of Fresenius was to mix the sulphide with carbonate of soda and cyanide of potassium, and place the mixture in the wide part of a tube of hard German glass, drawn out at one end to a capillary fineness. Carbonic anhydride, properly dried, was passed through the tube, and the portion containing the mixture heated to redness; in this way the arsenical sulphide was reduced, and the metal condensed in the capillary portion, where the smallest quantity could be recognised. A more elaborate and accurate process, based on the same principles, has been advocated by Mohr.[793]

A convenient quantity of carbonate of soda is added to the sulphide, and the whole mixed with a very little water, and gently warmed. The yellow precipitate is very soon dissolved, and then the whole is evaporated carefully, until it is in a granular, somewhat moist, adhesive state. It is now transferred to a glass tube, open at top and bottom, but the top widened into a funnel; this tube is firmly held perpendicularly on a glass plate, and the prepared sulphide hammered into a compact cylinder by the aid of a glass rod, which just fits the tube. The cylinder is now dried over a flame, until no more moisture is to be detected, and then transferred into a glass tube 4 or 5 inches long, and with one end drawn to a point (the weight of this tube should be first accurately taken). The tube is connected with the following series:—(1) A chloride of calcium tube; (2) a small bottle containing nitrate of silver solution; (3) a hydrogen-generating bottle containing zinc and sulphuric acid. The hydrogen goes through the argentic nitrate solution, leaving behind any sulphur and arsenic it may contain; it is then dried by chloride of calcium, and streams in a pure dry state over the cylinder of prepared sulphide (no error with regard to impurities in the gas is likely to occur; but in rigid inquiries it is advisable to heat a portion of the tube, previous to the insertion of the cylinder, for some time, in order to prove the absence of any external arsenical source); when it is certain that pure hydrogen, unmixed with air, is being evolved, the portion of the tube in which the cylinder rests is heated slowly to redness, and the metallic arsenic sublimes at a little distance from the source of heat. Loss is inevitable if the tube is too short, or the stream of hydrogen too powerful.

The tube after the operation is divided, the portion soiled by the soda thoroughly cleansed, and then both parts weighed; the difference between the weight of the empty tube and the tube + arsenic gives the metallic arsenic. This is the process as recommended by Mohr; it may, however, be pointed out that the glass tube itself loses weight when any portion of it is kept red-hot for some little time; and, therefore, unless the crust is required in the original tube, it is better to divide it, carefully weigh the arsenical portion, remove the crust, and then re-weigh. The method is not perfectly accurate. The mirror is not pure metallic arsenic (see p. 571), and if the white alkaline residue be examined, arsenic will be detected in it, the reason being that the arsenical sulphide generally contains pentasulphide of arsenic as well as free sulphur. Now the pentasulphide does not give up metallic arsenic when treated as before detailed; nor, indeed, does the trisulphide, if mixed with much sulphur, yield an arsenical crust. It is, therefore, of great moment to free the precipitate as much as possible from sulphur, before attempting the reduction.

The development of a reducing gas from a special and somewhat complicated apparatus is not absolutely necessary. The whole process of reduction, from beginning to end, may take place in a single tube by any of the following processes:—(1) The sulphide is mixed with oxalate of soda (a salt which contains no water of crystallisation), and the dry mixture is transferred to a suitable tube, sealed at one end. An arsenical mirror is readily obtained, and, if the heat is continued long enough, no arsenic remains behind—an excellent and easy method, in which the reducing gas is carbonic oxide, in an atmosphere of carbonic anhydride. (2) The sulphide is oxidised by aqua regia, and the solution evaporated to complete dryness. The residue is then dissolved in a few drops of water, with the addition of some largish grains of good wood charcoal (which absorb most of the solution), and the whole carefully dried. The mass is now transferred to a tube closed at one end, a little charcoal added in the form of an upper layer, and heat applied first to this upper layer, so as to replace the air with CO₂, and then to bring the whole tube gradually to redness from above downwards. In this case also the whole of the arsenic sublimes as a metallic mirror.

There are various other modifications, but the above are trustworthy, and quite sufficient. Brugelmann’s method of determining arsenic, elsewhere described, would appear to possess some advantages, and to promise well; but the writer has had no personal experience of it with regard to arsenic.

§ 747. Conversion of Arsenic into Arsenious Chloride (AsCl₃).—This process, first employed by Schneider and Fyfe, and afterwards modified by Taylor, differs from all the preceding, since an attempt is made to separate by one operation volatile metallic chlorides, and to destroy the organic matter, and thus obtain two liquids—one a distillate—tolerably clear and free from solid particles, whilst the mass in the retort retains such metals as copper, and is in every way easy to deal with.

Schneider and Fyfe employed sulphuric acid and common salt; but Taylor recommends hydrochloric acid, which is in every respect preferable. As recommended by Taylor, all matters, organic or otherwise, are to be completely desiccated before their introduction into a retort, and on these dried substances sufficient pure hydrochloric acid poured, and the distillation pushed to dryness. Every one is well aware how tedious is the attempt to dry perfectly the organs of the body (such as liver, &c.) at any temperature low enough to ensure against volatilisation of such a substance as, e.g., calomel. This drying has, therefore, been the great stumbling-block which has prevented the general application of the process. It will be found, however, that drying in the ordinary way is by no means necessary. The writer cuts up the solid organ (such as liver, brain, &c.) with scissors into small pieces, and transfers them to a retort fitted by an air-tight joint to a Liebig condenser; the condenser in its turn being connected with a flask by a tube passing through an india-rubber stopper dipping into a little water. Another tube from the same flask is connected with india-rubber piping, which is connected with a water-pump, the fall tube of which terminates in the basement of a house over a gully. The distillation is now carried on to carbonisation; on cooling, a second quantity of hydrochloric acid is added, and the last fraction of the distillate examined for arsenic. If any is found, a third distillation is necessary. At the termination of the operation the retort is washed with water, the solution filtered, and this solution and the distillate are each separately examined for arsenic. If properly performed, however, the second distillation brings over the whole of the arsenical chloride,[794] and none will be found in the retort. With the above arrangement there can be no odour, nor is there any loss of substance. In the distillate the arsenic can hardly be in the form of arsenious chloride, but rather arsenious acid and hydrochloric acid; for the chloride easily splits up in the presence of water into these substances. It is best to convert it into the trisulphide. Taylor[795] recommends evolving arsine in the usual way, and passing the arsine (AsH₃) into solution of silver nitrate, finally estimating it as an arseniate of silver. Objections with regard to the impurity of reagents should be met by blank experiments. Kaiser[796] has proposed and practised a modification of this method, which essentially consists in the use of sulphuric acid and sodic chloride (as in Schneider and Fyfe’s original process), and in passing the distillate first into a flask containing a crystal or two of potassium chlorate, and thence into an absorption bulb; in the latter most of the arsenic is found in the form of arsenic acid, the chloride having been oxidised in its passage. The apparatus is, however, complicated in this way without a corresponding advantage.[797] Lastly, E. Fischer[798] has shown that it is a considerable advantage to add from 10 to 20 c.c. of a saturated solution of ferrous chloride before distilling with HCl. In this way all the arsenic, whether as arsenic or arsenious acids, is easily converted into chloride.

2. ANTIMONY.

§ 748. Metallic Antimony.—Atomic weight, 120·3 (R. Schneider), 120·14 (Cook[799]); specific gravity, 6·715; fusing-point about 621° (1150° F.). In the course of analysis, metallic antimony may be seen as a black powder thrown down from solutions; as a film deposited on copper or platinum; and, lastly, as a ring on the inside of a tube from the decomposition of stibine. At a bright red-heat it is volatilised slowly, even when hydrogen is passed over it; chlorine, bromine, and iodine combine with it directly. It may be boiled in concentrated ClH without solution; but aqua regia, sulphides of potassium and sodium readily dissolve it. The distinction between thin films of this metal and of arsenic on copper and glass are pointed out at pp. 557 and 559. It is chiefly used in the arts for purposes of alloy, and enters to a small extent into the composition of fireworks (vide pp. 534 and 581).

§ 749. Antimonious Sulphide.—Sulphide of antimony = 336; composition in 100 parts, Sb 71·76, S 28·24. The commercial article, known under the name of black antimony, is the native sulphide, freed from silicious matter by fusion, and afterwards pulverised. It is a crystalline metallic-looking powder, of a steel-grey colour, and is often much contaminated with iron, lead, copper, and arsenic.

The amorphous sulphide (as obtained by saturating a solution of tartar emetic with SH₂) is an orange-red powder, soluble in potash and in ammonic, sodic, and potassic sulphides; and dissolving also in concentrated hydrochloric acid with evolution of SH₂. It is insoluble in water and dilute acid, scarcely dissolves in carbonate of ammonia, and is quite insoluble in potassic bisulphite. If ignited gently in a stream of carbonic acid gas, the weight remains constant. To render it anhydrous, a heat of 200° is required.

The recognition of arsenic in the commercial sulphide is most easily effected by placing 2 grms. or more in a suitable retort (with condenser), adding hydrochloric acid, and distilling. The chloride of arsenic passes over before the chloride of antimony; and by not raising the heat too high, very little antimony will come over, even if the distillation be carried almost to dryness. The arsenic is detected in the distillate by the ordinary methods.

Several lamentable accidents have happened through mistaking the sulphide of antimony for oxide of manganese, and using it with potassic chlorate for the production of oxygen. The addition of a drop of hydrochloric acid, it is scarcely necessary to say, will distinguish between the two.

Antimony is frequently estimated as sulphide. An amorphous tersulphide of mercury, containing a small admixture of antimonious oxide and sulphide of potassium, is known under the name of Kermes mineral, and has lately been employed in the vulcanising of india-rubber. Prepared in this way, the latter may be used for various purposes, and thus become a source of danger. It behoves the analyst, therefore, in searching for antimony, to take special care not to use any india-rubber fittings which might contain the preparation.

A pentasulphide of antimony (from the decomposition of Schleppe’s salt [Na₃Sb₆S₄ + 9H₂O], when heated with an acid) is used in calico-printing.

§ 750. Tartarated Antimony, Tartrate of Potash and Antimony, or Tartar Emetic, is, in a medico-legal sense, the most important of the antimonial salts. Its formula is KSbC₄H₄O₇H₂O, and 100 parts, theoretically, should contain 35·2 per cent. of metallic antimony. The B.P. gives a method of estimation of tartar emetic not free from error, and Professor Dunstan has proposed the following:—Dissolve 0·3 grm. of tartar emetic in 80 c.c. of water, add to this 10 c.c. of a 5 per cent. solution of sodium bicarbonate, and immediately titrate with a decinormal solution of iodine, using starch as an indicator. One c.c. of ⁿ⁄₁₀ iodine = 0·0166 grm. tartar emetic; therefore, if pure, the quantity used by 0·3 grm. should be 18 c.c. Tartar emetic occurs in commerce in colourless, transparent, rhombic, octahedral crystals, slightly efflorescing in dry air.

A crystal, placed in the subliming cell (p. 258), decrepitates at 193·3° (380° F.), sublimes at 248·8° (480° F.) very slowly and scantily, and chars at a still higher temperature, 287·7° (550° F.). On evaporating a few drops of a solution of tartar emetic, and examining the residue by the microscope, the crystals are either tetrahedra, cubes, or branched figures. 100 parts of cold water dissolve 5 of tartar emetic, whilst the same quantity of boiling water dissolves ten times as much, viz., 50. The watery solution decomposes readily with the formation of algæ; it gives no precipitate with ferrocyanide of potassium, chloride of barium, or nitrate of silver, unless concentrated.

§ 751. Metantimonic Acid, so familiar to the practical chemist from its insoluble sodium salt, is technically applied in the painting of glass, porcelain, and enamels; and in an impure condition, as antimony ash, to the glazing of earthenware.

§ 752. Pharmaceutical, Veterinary, and Quack Preparations of Antimony.[800]

(1) Pharmaceutical Preparations:—

Oxide of Antimony (Sb₂O₃) is a white powder, fusible at a low red heat, and soluble without effervescence in hydrochloric acid, the solution responding to the ordinary tests for antimony. Arsenic may be present in it as an impurity; the readiest means of detection is to throw small portions at a time on glowing charcoal, when very small quantities of arsenic will, under such conditions, emit the peculiar odour. Carbonate of lime appears also to have been found in the oxide of commerce.

Antimonial Powder is composed of one part of oxide of antimony and two parts of phosphate of lime; in other words, it ought to give 33·3 per cent. of Sb₂O₃.

Tartar Emetic itself has been already described. The preparations used in medicine are—

The Wine of Antimony (Vinum antimoniale), which is a solution of tartar emetic in sherry wine, and should contain 2 grains of the salt in each ounce of the wine (0·45 grm. in 100 c.c.).

Antimony Ointment (Unguentum antimonii tartarati) is a mechanical mixture of tartar emetic and lard, or simple ointment;[801] strength 20 per cent. There is no recorded case of conviction for the adulteration of tartar emetic; cream of tartar is the only probable addition. In such a case the mixture is less soluble than tartar emetic itself, and on adding a small quantity of carbonate of soda to a boiling solution of the suspected salt, the precipitated oxide at first thrown down, becomes redissolved.

Solution of Chloride of Antimony is a solution of the terchloride in hydrochloric acid; it is a heavy liquid of a yellowish-red colour, powerfully escharotic; its specific gravity is 1·47; on dilution with water, the whitish-yellow oxychloride of antimony is precipitated. One drachm (3·549 c.c.) mixed with 4 ounces (112 c.c.) of a solution of tartaric acid (·25 : 4) gives a precipitate with SH₂, which weighs at least 22 grains (1·425 grm.). This liquid is used on very rare occasions as an outward application by medical men; farriers sometimes employ it in the foot-rot of sheep.

Purified Black Antimony (Antimonium nigrum purificatum) is the purified native sulphide Sb₂S₃; it should be absolutely free from arsenic.

Sulphurated Antimony (Antimonium sulphuratum) is a mixture of sulphide of antimony, Sb₂S₃, with a small and variable amount of oxide, Sb₂O₃. The P.B. states that 60 grains (3·888 grms.) dissolved in ClH, and poured into water, should give a white precipitate of oxychloride of antimony, which (properly washed and dried) weighs about 53 grains (3·444 grms.). The officinal compound pill of subchloride of mercury (Pilula hydrargyri subchloridi composita) contains 1 grain (·0648 grm.) of sulphurated antimony in every 5 grains (·324 grm.), i.e., 20 per cent.

(2) Patent and Quack Pills:—

Dr. J. Johnson’s Pills.—From the formula each pill should contain:—

Grains. Grms.

Compound Extract of Colocynth, 2 ·5 = ·162

Calomel, ·62 = ·039

Tartar Emetic, ·04 = ·002

Oil of Cassia, ·12 = ·007

3 ·28 = ·210

The oil of cassia can be extracted by petroleum ether; the calomel sublimed and identified by the methods given in the article on “Mercury”; the antimony deposited in the metallic state on platinum or tin; and the colocynth extracted by dissolving in water, acidifying, and shaking up with chloroform. On evaporating the chloroform the residue should taste extremely bitter; dissolved in sulphuric acid it changes to a red colour, and dissolved in Fröhde’s reagent to a cherry-red. It should also have the ordinary reactions of a glucoside.

Mitchell’s Pills contain in each pill:—

Grains. Grms.

Aloes, 1 ·1 = ·070

Rhubarb, 1 ·6 = ·103

Calomel, ·16 = ·010

Tartar Emetic, ·05 = ·003

2 ·91 = ·186

The mineral substances in this are easy of detection by the methods already given; the aloes by the formation of chrysammic acid, and the rhubarb by its microscopical characters.

Dixon’s Pills probably contain the following in each pill:—

Grains. Grms.

Compound Extract of Colocynth, 2 ·0 = ·1296

Rhubarb, 1 ·0 = ·0648

Tartar Emetic, ·06 = ·0038

3 ·06 = ·1982

(3) Antimonial Medicines, chiefly Veterinary:[802]—

Liver of Antimony is a preparation formerly much used by farriers. It is a mixture of antimonious oxide, sulphide of potassium, carbonate of potassium, and undecomposed trisulphide of antimony (and may also contain sulphate of potassium), all in very undetermined proportions. When deprived of the soluble potash salts, it becomes the washed saffron of antimony of the old pharmacists. A receipt for a grease-ball, in a modern veterinary work, gives, with liver of antimony, cream of tartar and guaiacum as ingredients.

Hind’s Sweating-ball is composed of 60 grains (3·888 grms.) of tartar emetic and an equal portion of assafœtida, made up into a ball with liquorice-powder and syrup. The assafœtida will be readily detected by the odour, and the antimony by the methods already recommended.

Ethiops of Antimony, very rarely used now, is the mechanical mixture of the sulphides of antimony and mercury—proportions, 3 of the former to 2 of the latter.

The Flowers of Antimony is an impure oxysulphide of antimony, with variable proportions of trioxide and undecomposed trisulphide.

Diaphoretic Antimony (calcined antimony) is simply antimoniate of potash.

Glass of Antimony is a mixture of sulphide and oxide of antimony, contaminated with a small quantity of silica and iron.

A quack pill, by name, Ward’s Red Pill, is said to contain glass of antimony and dragon’s blood.

Antimonial Compounds used in Pyrotechny:—

Blue Fire:—

Antimonious sulphide, 1

Sulphur, 2

Nitre, 6

This composition is used for the blue or Bengal signal-light at sea. Bisulphide of carbon and water are solvents which will easily separate the powder into its three constituents.

Crimson Fire:—

Potassic Chlorate, 17· 25

Alder or Willow Charcoal, 4· 5

Sulphur, 18·

Nitrate of Strontia, 55·

Antimonious Sulphide, 5· 5

The spectroscope will readily detect strontia and potassium, and the analysis presents no difficulty. In addition to these a very great number of other pyrotechnical preparations contain antimony.

§ 753. Alloys.—Antimony is much used in alloys. The ancient Pocula emetica, or everlasting emetic cups, were made of antimony, and with wine standing in them for a day or two, they acquired emetic properties. The principal antimonial alloys are Britannia and type metal, the composition of which is as follows:—

Tin, per cent. Copper, per cent. Antimony, per cent.

Britannia Metal, Best, 92 ·0 1 ·8 6 ·2

Common, 92 ·1 2 ·0 5 ·9

For Castings, 92 ·9 1 ·8 5 ·3

For Lamps, 94 ·0 1 ·3 4 ·7

Tea Lead, per cent. Antimony, per cent. Block Tin, per cent.

Type Metal, - (1.) 75 20 5

(2.) 70 25 5

Metal for Stereotype, 84 ·2 13 ·5 2 ·3

There is also antimony in brass, concave mirrors, bell-metal, &c.

§ 754. Pigments.—Cassella and Naples yellow are principally composed of the antimoniate of lead.

Antimony Yellow is a mixture of antimoniate of lead with basic chloride of lead.

§ 755. Dose.—A medicinal dose of a soluble antimonial salt should not exceed 97·2 mgrms. (1¹⁄₂ grain). With circumstances favouring its action, a dose of 129·6 mgrms. (2 grains) has proved fatal;[803] but this is quite exceptional, and few medical men would consider so small a quantity dangerous for a healthy adult, especially since most posological tables prescribe tartar emetic as an emetic in doses from 64·8 to 194·4 mgrms. (1 to 3 grains). The smallest dose which has killed a child appears to be 48·5 mgrms. (³⁄₄ grain).[804] The dose of tartar emetic for horses and cattle is very large, as much as 5·832 grms. (90 grains) being often given to a horse in his gruel three times a day. 3·8 grms. (60 grains) are considered a full, but not an excessive, dose for cattle; ·38 grm. (6 grains) is used as an emetic for pigs, and half this quantity for dogs.

§ 756. Effects of Tartar Emetic and of Antimony Oxide on Animals.—Large doses of tartar emetic act on the warm-blooded animals as on man; whether the poison is taken by the mouth, or injected subcutaneously, all animals able to vomit[805] do so. The heart’s action, at first quickened, is afterwards slowed, weakened, and lastly paralysed. This action is noticed in cold as well as in warm-blooded animals. It is to be ascribed to a direct action on the heart; for if the brain and spinal cord of the frog be destroyed—or even if a solution of the salt be applied direct to the frog’s heart separated from the body—the effect is the same. The weak action of the heart, of course, causes the blood-pressure to diminish, and the heart stops in diastole. The voluntary muscles of the body are also weakened; the breathing is affected, partly from the action on the muscles. The temperature of the body is depressed (according to F. A. Falck’s researches) from 4·4° to 6·2°.

The effect of small doses given repeatedly to animals has been several times investigated. Dr. Nevin[806] experimented upon eleven rabbits, giving them tartar emetic four times a day in doses of 32·4 mgrms. (¹⁄₂ grain), 64·8 mgrms. (1 grain), and 129·6 mgrms. (2 grains). Five died, the first after four, the last after seventeen days; three were killed after one, three, and four days respectively, two after an interval of fourteen days, and one thirty-one days after taking the last dose. There was no vomiting; diarrhœa was present in about half the number; one of the rabbits, being with young, aborted. The chief symptoms were general dulness, loss of appetite, and in a few days great emaciation. Four of the five that died were convulsed before death, and several of the animals exhibited ulcers of the mucous membrane of the mouth, in places with which the powder had come in contact. Caillol and Livon have also studied the action of small doses of the white oxide of antimony given in milk to cats. A cat took in this way in 109 days ·628 grm. The animal passed gradually into a cachectic state, diarrhœa supervened, and it died miserably thin and exhausted.

§ 757. Effects of Tartar Emetic on Man.[807]—The analogy between the symptoms produced by arsenic and antimony is striking, and in some acute cases of poisoning by tartar emetic, there is but little (if any) clinical difference. If the dose of tartar emetic is very large, there may be complete absence of vomiting, or only a single evacuation of the stomach. Thus, in a case mentioned by Taylor, in which a veterinary surgeon swallowed by mistake 13 grms. (200 grains) of tartar emetic, vomiting after fifteen minutes could only be induced by tickling the throat. So, again, in the case reported by Mr. Freer, a man, aged 28, took 7·77 grms. (120 grains) of tartar emetic by mistake for Epsom salts; he vomited only once; half an hour after taking the poison he had violent pain in the stomach and abdomen, and spasmodic contraction of the abdomen and arms; the fingers were firmly contracted, the muscles quite rigid, and there was involuntary aqueous purging. After six hours, during which he was treated with green tea, brandy, and decoction of oak-bark, he began to recover, but suffered for many nights from profuse perspirations.

With more moderate and yet large doses, nausea and vomiting are very prominent symptoms, and are seldom delayed more than half an hour. The regular course of symptoms may therefore be summed up thus:—A metallic taste in the mouth, repeated vomitings, which are sometimes bloody, great faintness and depression, pains in the abdomen and stomach, and diarrhœa, which may be involuntary. If the case is to terminate fatally, the urine is suppressed, the temperature falls, the face becomes cyanotic, delirium and convulsions supervene, and death occurs in from two to six days. Antimony, like arsenic, often produces a pustular eruption. Solitary cases deviate more or less from the course described, i.e., severe cramps affecting all the muscles, hæmorrhage from the stomach, kidney, or bowel, and death from collapse in a few hours, have all been noticed. In a case recorded by Mr. Morley,[808] a surgeon’s daughter, aged 18, took by mistake an unknown quantity of antimonial wine; she soon felt sleepy and powerless, and suffered from the usual symptoms in combination with tetanic spasms of the legs. She afterwards had enteritis for three weeks, and on recovery her hair fell off. Orfila relates a curious case of intense spasm of the gullet from a large dose of tartar emetic.

§ 758. Chronic Antimonial Poisoning.—The cases of Palmer and J. P. Cook, M. Mullen, Freeman, Winslow, Pritchard, and the remarkable Bravo case have, in late years, given the subject of chronic antimonial poisoning a considerable prominence. In the trials referred to, it was shown that medical men might easily mistake the effects of small doses of antimony given at intervals for the action of disease—the symptoms being great nausea, followed by vomiting, chronic diarrhœa, alternating with constipation, small frequent pulse, loss of voice, great muscular weakness, depression, with coldness of the skin and a clammy perspiration. In the case of Mrs. Pritchard,[809] her face was flushed, and her manner so excited as to give an ordinary observer the idea that she had been drinking; and with the usual symptoms of vomiting and purging, she suffered from cramps in the hands. Dr. Pritchard tried to make it appear that she was suffering from typhoid fever, which the symptoms in a few respects only resembled.

According to Eulenberg, workmen, exposed for a long period to the vapour of the oxide of antimony, suffer pain in the bladder and a burning sensation in the urethra, and continued inhalation even leads to impotence and wasting of the testicles.[810]

§ 759. Post-mortem Appearances.—The effect of large doses of tartar emetic is mainly concentrated upon the gastro-intestinal mucous membrane. There is an example in the museum of University College Hospital of the changes which resulted from the administration of tartar emetic in the treatment of pneumonia. These are ascribed in the catalogue, in part to the local action of the medicine, and in part to the extreme prostration of the patient. In the preparation (No. 1052) the mucous membrane over the fore border of the epiglottis and adjacent part of the pharynx has been destroyed by sloughing; the ulceration extends into the upper part of the œsophagus. About an inch below its commencement, the mucous membrane has been entirely removed by sloughing and ulceration, the circular muscular fibres being exposed. Above the upper limit of this ulcer, the mucous membrane presents several oval, elongated, and ulcerated areas, occupied by strips of mucous membrane which have sloughed. In other places, irregular portions of the mucous membrane, of a dull ashen-gray colour, have undergone sloughing; the edges of the sloughing portion are of colours varying from brown to black.

It is seldom that so much change is seen in the gullet and pharynx as this museum preparation exhibits; but redness, swelling, and the general signs of inflammation are seldom absent from the stomach and some parts of the intestines. On the lining membrane of the mouth, ulcers and pustules have been observed.

In Dr. Nevin’s experiments on the chronic poisoning of rabbits already referred to, the post-mortem appearances consisted in congestion of the liver in all the rabbits; in nearly all there was vivid redness of the stomach; in two cases there was ulceration; in some, cartilaginous hardness of the pylorus; while, in others, the small intestines presented patches of inflammation. In two of the rabbits the solitary glands throughout the intestines were prominent, yellow in colour, and loaded with antimony. The colon and rectum were healthy, the kidneys congested; the lungs were in most congested, in some actually inflamed, or hepatised and gorged with blood. Bloody extravasations in the chest and abdomen were frequent.

Saikowsky,[811] in feeding animals daily with antimony, found invariably in the course of fourteen to nineteen days fatty degeneration of the liver, and sometimes of the kidney and heart. In the experiment of Caillol and Livon also all the organs were pale, the liver had undergone fatty degeneration, and the lung had its alveoli filled with large degenerated cells, consisting almost entirely of fat. The mesenteric glands also formed large caseous masses, yellowish-white in colour, which, under the microscope, were seen to be composed of fatty cells, so that there is a complete analogy between the action of arsenic and antimony on the body tissues.

§ 760. Elimination of Antimony.—Antimony is mainly eliminated by the urine. In 1840, Orfila showed to the Académie de Médecine metallic antimony, which he had extracted from a patient who had taken ·12 grm. of tartar emetic in twenty-four hours. He also obtained antimony from an old woman, aged 80, who twelve hours before had taken ·6 grm. (9¹⁄₄ grains)—a large dose, which had neither produced vomiting nor purging. In Dr. Kevin’s experiments on rabbits, antimony was discovered in the urine after the twelfth dose, and even in the urine of an animal twenty-one days after the administration of the poison had been suspended.

§ 761. Antidotes for Tartar Emetic.—Any infusion containing tannin or allied astringent principles, such as decoctions of tea, oak-bark, &c., may be given with advantage in cases of recent poisoning by tartar emetic, for any of the salt which has been expelled by vomiting may in this way be decomposed and rendered harmless. The treatment of acute poisoning which has proved most successful, has been the encouraging of vomiting by tickling the fauces, giving strong green tea and stimulants. (See Appendix.)

§ 762. Effects of Chloride or Butter of Antimony.—Only a few cases of poisoning by butter of antimony are on record: its action, generally speaking, on the tissues is like that of an acid, but there has been considerable variety in the symptoms. Five cases are recorded by Taylor; three of the number recovered after taking respectively doses of 7·7 grms. (2 drachms) and 15·5 grms. (4 drachms), and two died after taking from 56·6 to 113 grms. (2 to 4 ounces). In one of these cases the symptoms were more like those of a narcotic poison, in the other fatal case there was abundant vomiting with purging. The autopsy in the first case showed a black appearance from the mouth to the jejunum, as if the parts had been charred, and extensive destruction of the mucous membrane. In the other case there were similar changes in the stomach and the upper part of the intestines, but neither the lips nor the lower end of the gullet were eroded. In a case recorded by Mr. Barrington Cooke,[812] a farmer’s wife, aged 40, of unsound mind, managed to elude the watchfulness of her friends, and swallowed an unknown quantity of antimony chloride about 1.30 P.M. Shortly afterwards she vomited several times, and had diarrhœa; at 2.30 a medical man found her lying on her back insensible, and very livid in the face and neck. She was retching, and emitting from her mouth a frothy mucous fluid, mixed with ejected matter of a grumous colour; the breathing was laboured and spasmodic; the pulse could not be felt, and the body was cold and clammy. She expired at 3.30, about one hour and a half from the commencement of symptoms, and probably within two hours from the taking of the poison. The autopsy showed no corrugation of the tongue or inner surface of the lining membrane of the mouth, and no appearance of the action of a corrosive upon the lips, fauces, or mucous membrane of the œsophagus. The whole of the mucous membrane of the stomach was intensely congested, of a dark and almost black colour, the rest of the viscera were healthy. Chemical analysis separated antimony equivalent to nearly a grm. (15 grains) of the chloride, with a small quantity of arsenic, from the contents of the stomach.

§ 763. Detection of Antimony in Organic Matters.—In acute poisoning by tartar emetic it is not impossible to find a mere trace only in the stomach, the greater part having been expelled by vomiting, which nearly always occurs early, so that the most certain method is, where possible, to analyse the ejected matters. If it should be suspected that a living person is being slowly poisoned by antimony, it must be remembered that the poison is mainly excreted by the kidneys, and the urine should afford some indication. The readiest way to test is to collect a considerable quantity of the urine (if necessary, two or three days’ excretion), concentrate by evaporation, acidify, and then transfer the liquid to a platinum dish, in which is placed a slip of zinc. The whole of the antimony is in time deposited on the platinum dish, and being thus concentrated, may be subsequently identified in any way thought fit.

Organic liquids are boiled with hydrochloric acid; organic solids are extracted with the same acid in the manner described (p. 51); or, if the distillation process given at p. 576 be employed, the antimony may be found partly in the distillate, and partly in the retort. In any case, antimony in solution may be readily detected in a variety of ways—one of the most convenient being to concentrate on tin or platinum, to dissolve out the antimonial film by sulphide of ammonium, and thus produce the very characteristic orange sulphide.

If a slip of pure tinfoil be suspended for six hours in a solution, which should not contain more than one-tenth of its bulk of ClH, and exhibit no stain or deposit, it is certain that antimony cannot be present. It may also conveniently be deposited on a platinum dish,[813] by filling the same with the liquid properly acidulated, and inserting a rod of zinc; the metallic antimony can afterwards be washed, dried, and weighed.

Reinsch’s and Marsh’s tests have been already described (pp. 558 and 559), and require no further notice. There is, however, a very beautiful and delicate means of detecting antimony, which should not be omitted. It is based upon the action of stibine (SbH₃) on sulphur.[814] When this gas is passed over sulphur, it is decomposed according to equation, 2SbH₃ + 6S = Sb₂S₃ + 3SH₂, the action taking place slowly in diffused daylight, but very rapidly in sunshine. An ordinary flask for the evolution of hydrogen (either by galvanic processes or from zinc and sulphuric acid), with its funnel and drying-tubes, is connected with a narrow tube having a few fragments of sulphur, kept in place by plugs of cotton wool. The whole apparatus is placed in sunshine; if no orange colour is produced when the hydrogen has been passing for some time, the liquid to be tested is poured in gradually through the funnel, and if antimony should be present, the sulphur acquires a deep orange colour. This is distinct even when so small a quantity as ·0001 grain has been added through the funnel. The sulphide of antimony thus mixed with sulphur can, if it is thought necessary, be freed from the sulphur by repeated exhaustion with bisulphide of carbon. The stibine does not, however, represent all the antimony introduced, a very large proportion remaining in the evolution flask;[815] hence it cannot be employed for quantitative purposes. Moreover, the test can, of course, only be conveniently applied on sunny days, and is, therefore, in England more adapted for summer.[816] Often, however, as mentioned elsewhere, when the analyst has no clue whatever to the nature of the poison, it is convenient to pass SH₂ in the liquid to saturation.[817] In such a case, if antimony is present (either alone or in combination with other sulphides), it remains on the filter, and must be separated and identified as follows:—The sulphides are first treated with a solution of carbonate of ammonia, which will dissolve arsenic, if present, and next saturated in situ with pure sulphide of sodium, which will dissolve out sulphide of antimony, if present. The sulphide of antimony will present the chemical characters already described, more particularly—

(1) It will evolve SH₂ when treated with HCl, and at the same time pass into solution.[818]

(2) The solution evaporated to get rid of free HCl gives with water a thick cheesy precipitate of basic chloride of antimony. This may be seen if only a drop or two of the solution be taken and tested in a watch-glass.

(3) If tartaric acid be added to the solution, this precipitation does not occur.

(4) The solution from (3) gives an orange precipitate with SH₂.

Such a substance can only be sulphide of antimony. With regard to (2), bismuth would act similarly, but under the circumstances could not be present, for the sulphide of bismuth is insoluble in sodic sulphide.

§ 764. Quantitative Estimation.—The quantitative estimation of antimony is best made by some volumetric process, e.g., the sulphide can be dissolved in HCl, some tartrate of soda added, and then carbonate of soda to weak alkaline reaction. The strength of the solution of tartarised antimony thus obtained can now be estimated by a decinormal solution of iodine, the end reaction being indicated by the previous addition of a little starch solution, or by a solution of permanganate of potash, either of which should be standardised by the aid of a solution of tartar emetic of known strength.

3. CADMIUM.

§ 765. Cadmium, Cd = 112; specific gravity, 8·6 to 8·69; fusing-point, 227·8° (442° F.); boiling-point, 860° (1580° F.).—Cadmium in analysis is seldom separated as a metal, but is estimated either as oxide or sulphide.

§ 766. Cadmium Oxide, CdO = 128—cadmium, 87·5 per cent.; oxygen, 12·5 per cent.—is a yellowish or reddish-brown powder, non-volatile even at a white heat; insoluble in water, but dissolving in acids. Ignited on charcoal, it is reduced to metal, which volatilises, and is then deposited again as oxide, giving to the coal a distinct coat of an orange-yellow colour in very thin layers; in thicker layers, brown.

§ 767. Cadmium Sulphide, CdS = 144—Cd, 77·7 per cent.; S, 22·3 per cent.—known as a mineral termed Greenockite. When prepared in the wet way, it is a lemon-yellow powder, which cannot be ignited in hydrogen without loss, and is insoluble in water, dilute acids, alkalies, alkaline sulphides, sulphate of soda, and cyanide of potassium. The solution must not contain too much hydrochloric acid, for the sulphide is readily soluble with separation of sulphur in concentrated hydrochloric acid. It may be dried in the ordinary way at 100° without suffering any decomposition.

§ 768. Medicinal Preparations.—The Iodide of Cadmium (CdI₂) occurs in white, flat, micaceous crystals, melting at about 215·5° (419·9° F.), and at a dull red heat giving off violet vapour. In solution, the salt gives the reactions of iodine and cadmium. The ointment of iodide of cadmium (Unguentum cadmii iodidi) contains the iodide in the proportion of 62 grains to the ounce, or 14 per cent.

Cadmium Sulphate is officinal in the Belgian, Portuguese, and French pharmacopœias.

§ 769. Cadmium in the Arts, &c.—Cadmium is used in various alloys. The sulphide is found as a colouring ingredient in certain toilet soaps, and it is much valued by artists as a pigment. The iodide of cadmium is employed in photography, and an amalgam of metallic cadmium to some extent in dentistry.

§ 770. Fatal Dose of Cadmium.—Although no deaths from the use of cadmium appear to have as yet occurred, its use in photography, &c., may lead to accidents. There can be no question about the poisonous action of cadmium, for Marmé,[819] in his experiments on it with animals, observed giddiness, vomiting, syncope, difficulty in respiration, loss of consciousness, and cramps. The amount necessary to destroy life can only be gathered from the experiments on animals. A strong hound died after the injection of ·03 grm. (·462 grain) subcutaneously of a salt of cadmium; rabbits are poisoned if from 19·4 to 38·8 mgrms. (·3 to ·6 grain) are introduced into the stomach. A watery solution of ·5 grm. (7·5 grains) of the bromide administered to a pigeon caused instant death, without convulsion; the same dose of the chloride killed a second pigeon in six minutes; ·25 grm. (3·85 grains) of sulphite of cadmium administered to a pigeon excited vomiting, and after two hours diarrhœa; it died in eight days. Another pigeon died from a similar dose in fourteen days, and cadmium, on analysis, was separated from the liver. From the above cases it would seem probable that 4 grms. (61·7 grains) would be a dangerous dose of a soluble salt of cadmium for an adult, and that in a case of chronic poisoning it would most probably be found in the liver.

§ 771. Separation and Detection of Cadmium.—If cadmium be in solution, and the solution is not too acid, on the addition of SH₂ there is precipitated a yellow sulphide, which is distinguished from antimony and arsenical sulphides by its insolubility in ammonia and alkaline sulphides. Should all three sulphides be on the filter (an occurrence which will seldom, perhaps never, happen), the sulphide of arsenic can be dissolved out by ammonia, the antimony by sulphide of sodium, leaving the sulphide of cadmium as the residue.[820]

The further tests of the sulphide are:—

(1) It dissolves in dilute nitric acid to a colourless fluid, with separation of sulphur.

(2) The solution, filtered and freed from excess of nitric acid by evaporation, gives with a solution of ammonic carbonate a white precipitate of carbonate of cadmium insoluble in excess. This distinguishes it from zinc, which gives a similar white precipitate, but is soluble in the excess of the precipitant.

(3) The carbonate thus obtained, heated on platinum foil, is changed into the brown-red non-volatile oxide.

(4) The oxide behaves on charcoal as already detailed.

(5) A metallic portion can be obtained by melting the oxide with cyanide of potassium; it is between zinc and tin in brilliancy, and makes a mark on paper like lead, but not so readily. There are many other tests, but the above are conclusive.

If cadmium in any case be specially searched for in the organs or tissues, the latter should be boiled with nitric acid. The acid solution is filtered, saturated with caustic potash, evaporated to dryness, and ignited; the residue is dissolved in dilute hydrochloric acid, and treated after filtration with SH₂. Cadmium may also be estimated volumetrically by digesting the sulphide in a stoppered flask with ferric chloride and hydrochloric acid; the resulting ferrous compound is titrated with permanganate, each c.c. of a d.n. solution of permanganate = ·0056 grm. of cadmium.

II.—PRECIPITATED BY HYDRIC SULPHIDE IN HYDROCHLORIC ACID SOLUTION—BLACK. Lead—Copper—Bismuth—Silver—Mercury.

1. LEAD.

§ 772. Lead, Pb = 207.—Lead is a well-known bluish-white, soft metal; fusing-point, 325°; specific gravity, 11·36.

Oxides of Lead.—The two oxides of lead necessary to notice here briefly are—litharge and minium.

Litharge, or Oxide of Lead, PbO = 223; specific gravity, 9·2 to 9·5—Pb 92·82 per cent., O 7·18—is either in crystalline scales, a fused mass, or a powder, varying in colour (according to its mode of preparation) from yellow to reddish-yellow or orange. When prepared below the temperature of fusion it is called “massicot.” It may be fused without alteration in weight; in a state of fusion it dissolves silicic acid and silicates of the earths. It must not be fused in platinum vessels.

Minium, or Red Lead, 2PbO, PbO₂; specific gravity, 9·08, is a compound of protoxide of lead with the dioxide. It is of a brilliant red colour, much used in the arts, and especially in the preparation of flint-glass.

§ 773. Sulphide of Lead, PbS = 239; Pb, 86·61 per cent., S, 13·39 per cent., occurring in the usual way, is a black precipitate insoluble in water, dilute acids, alkalies, and alkaline sulphides. It dissolves in strong nitric acid with separation of sulphur, and in strong hydrochloric acid, with evolution of SH₂. Fuming nitric acid does not separate sulphur, but converts the sulphide into sulphate.

§ 774. Sulphate of Lead, PbSO₄ = 303; specific gravity, 6·3; PbO, 73·61 per cent., SO₃, 26·39 per cent., when produced artificially is a heavy white powder, of great insolubility in water, 22,800 parts of cold water dissolving only one of lead sulphate; and if the water contains sulphuric acid, no less than 36,500 parts of water are required. The salts of ammonia (especially the acetate and tartrate) dissolve the sulphate, and it is also soluble in hyposulphite of soda. The sulphate can be readily changed into the carbonate of lead, by boiling it with solutions of the alkaline carbonates. The sulphate of lead, fused with cyanide of potassium, yields metallic lead; it may be also reduced on charcoal, and alone it may be fused without decomposition, provided reducing gases are excluded.

§ 775. Acetate of Lead, Sugar of Lead, Pb(C₂H₃O₂)₂3OH₂ = 379, is found in commerce in white, spongy masses composed of acicular crystals. It may, however, be obtained in flat four-sided prisms. It has a sweet metallic taste, is soluble in water, and responds to the usual tests for lead. The P.B. directs that 38 grains dissolved in water require, for complete precipitation, 200 grain measures of the volumetric solution of oxalic acid, corresponding to 22·3 grains of oxide of lead.

§ 776. Chloride of Lead, PbCl₂ = 278; specific gravity, 5·8; Pb, 74·48 per cent., Cl, 25·52 per cent., is in the form of brilliant crystalline needles. It is very insoluble in cold water containing hydrochloric or nitric acids. According to Bischof, 1635 parts of water containing nitric acid dissolve one part only of chloride of lead. It is insoluble in absolute alcohol, and sparingly in alcohol of 70 to 80 per cent. It fuses below red heat without losing weight; at higher temperatures it may be decomposed.

Carbonate of Lead.—The commercial carbonate of lead (according to the exhaustive researches of Wigner and Harland[821]) is composed of a mixture of neutral carbonate of lead and hydrate of lead, the best mixture being 25 per cent. of hydrate, corresponding to an actual percentage of 12·3 per cent. carbonic acid. The nearer the mixture approximates to this composition the better the paint; whilst samples containing as much as 16·33 per cent., or as little as 10·39 per cent., of CO₂ are practically useless.

§ 777. Preparations of Lead used in Medicine, the Arts, &c.

(1) Pharmaceutical:—

Lead Plaster (Emplastrum plumbi) is simply a lead soap, in which the lead is combined with oleic and margaric acids, and contains some mechanically included glycerin.

Lead Iodide, PbI₂, is contained in the Emplastrum plumbi iodidi to the extent of 10 per cent., and in the Unguentum plumbi iodidi to the extent of about 12·5 per cent.

Acetate of Lead is contained in a pill, a suppository, and an ointment. The pill (Pilula plumbi cum opio) contains 75 per cent. of lead acetate, and 12·5 per cent. of opium, the rest confection of roses. The suppository (Suppositoria plumbi composita) contains 20 per cent. of acetate of lead, and 6·6 per cent. of opium, mixed with oil of theobroma. The ointment (Unguentum plumbi acetatis) contains 20·6 per cent. of lead acetate, mixed with benzoated lard.

The solution of subacetate of lead (Liquor plumbi subacetatis) is the subacetate, Pb(C₂H₃O₂)₂PbO, dissolved in water; it contains nearly 27 per cent. of subacetate.

A dilute solution of the stronger, under the name of Liquor plumbi subacetatis dilutus, and commonly called Goulard water, is prepared by mixing 1 part (by volume) of the solution and 1 part of spirit, and 78 parts of distilled water; the strength is equal to 1·25 per cent.

There is an ointment, called the Compound Ointment of subacetate of lead, which contains the subacetate in about the proportion of 2 per cent. of the oxide, the other constituents being camphor, white wax, and almond oil.

Carbonate of Lead.—The ointment (Unguentum plumbi carbonatis) should contain about 12·5 per cent. of the carbonate, and the rest simple ointment.

(2) Quack Nostrums, &c.:—

The quack medicines composed of lead are not very numerous.

Liebert’s Cosmetique Infaillible is said to have for its basis nitrate of lead.

One of “Ali Ahmed’s Treasures of the Desert,” viz., the antiseptic malagma, is a plaster made up of lead plaster 37·5 per cent., frankincense 25 per cent., salad oil 25 per cent., beeswax 12·5 per cent.

Lewis’ Silver Cream contains white precipitate and a salt of lead.

Goulard’s Balsam is made by triturating acetate of lead with hot oil of turpentine.

There are various ointments in use made up of litharge. Some herbalists in the country (from cases that have come under the writer’s own knowledge) apply to cancerous ulcers, &c., a liniment of linseed and other common oils mixed with litharge and acetate of lead.

Acetate of lead may also be found as a constituent of various eye-waters.

(3) Preparations of Lead used in the Arts, &c.:—

Ledoyen’s Disinfecting Fluid has for its basis nitrate of lead.

In various hair-dyes the following are all used:—Litharge, lime, and starch; lime and carbonate of lead; lime and acetate of lead; litharge, lime, and potassic bicarbonate. The detection of lead in the hair thus treated is extremely easy; it may be dissolved out by dilute nitric acid.

Lead Pigments.—The principal pigments of lead are white, yellow, and red.

White Pigments:—

White Lead, Flake White Ceruse, Mineral White, are so many different names for the carbonate of lead already described.

Newcastle White is white lead made with molasses vinegar.

Nottingham White.—White lead made with alegar (sour ale), often, however, replaced by permanent white, i.e., sulphate of baryta.

Miniature Painters’ White, White Precipitate of Lead, is simply lead sulphate.

Pattison’s White is an oxychloride of lead, PbCl₂PbO.

Yellow Pigments:—

Chrome Yellow may be a fairly pure chromate of lead, or it may be mixed with sulphates of lead, barium, and calcium. The pigment known as “Cologne yellow” consists of 25 parts of lead chromate, 15 of lead sulphate, and 60 of calcic sulphate. The easiest method of analysing chrome yellow is to extract with boiling hydrochloric acid in the presence of alcohol, which dissolves the chromium as chloride, and leaves undissolved chloride of lead, sulphate of lead, and other substances insoluble in ClH. Every grain of chromate of lead should yield 0·24 grain of oxide of chromium, and 0·4 grain of chloride of lead.

Turner’s Yellow, Cassella Yellow, Patent Yellow, is an oxychloride of lead (PbCl₂7PbO) extremely fusible.

Dutch Pink sometimes contains white lead.

Red Pigments:—

Chrome Red is a bichromate of lead.

Red Lead or Minium is the red oxide of lead.

Orange Red is an oxide prepared by calcining the carbonate.

The chief preparations of lead which may be met with in the arts, in addition to the oxides and the carbonate, are—

The Nitrate of Lead, much used in calico-printing.

The Pyrolignite of Lead, which is an impure acetate used in dyeing; and

The Sulphate of Lead is a by-product in the preparation of acetate of aluminium for dyeing.

The alloys containing lead are extremely numerous; but, according to the experiments of Knapp,[822] the small quantity of lead in those used for household purposes has no hygienic importance.

§ 778. Statistics of Lead-Poisoning.—In the ten years, 1883 to 1892, no less than 1043 persons died from the effects of lead; of these, 3 only were suicidal, the remaining 1040 were mainly from the manufacture of white lead or from the use of lead in the arts or from the accidental contamination of food or drink.

The following table shows in what manner the 1040 were distributed as to age and sex:—

DEATHS FROM LEAD-POISONING IN ENGLAND AND WALES DURING THE TEN YEARS 1883-1892.

Ages, 0-1 1-5 5-15 15-25 25-65 65 and above Total

Males, ... 4 14 44 733 36 831

Females, 3 5 ... 68 129 4 209

Total, 3 9 14 112 862 40 1040

§ 779. Lead as a Poison.—All the compounds of lead are said to be poisonous; but this statement cannot be regarded as entirely correct, for the sulphocyanide has been proved by experiment not to be so,[823] and the sulphide is also probably inactive. In the treatment of cases of lead-poisoning, the flowers of sulphur given internally appear to be successful.[824]

Lead-poisoning, either in its obscure form (producing uric acid in the blood, and, as a consequence, indigestion and other evils), or in the acute form (as lead colic and various nervous affections), is most frequent among those who are habitually exposed to the influence of the metal in its different preparations, viz., workers of lead, house-painters, artists, gilders, workers of arsenic, workers of gold, calico-printers, colourists, type-founders, type-setters, shot-founders, potters, faience makers, braziers, and many others.[825] In white-lead factories so large a number of the employés suffer from poisoning that it has excited more than once the attention of the Government.[826]

Lead, again, has been found by the analyst in most of the ordinary foods, such as flour, bread, beer, cider, wines, spirits, tea, vinegar, sugar, confectionery, &c., as well as in numerous drugs, especially those manufactured by the aid of sulphuric acid (the latter nearly always containing lead), and those salts or chemical products which (like citric and tartaric acids) are crystallised in leaden pans. Hence it follows that in almost everything eaten or drunk the analyst, as a matter of routine, tests for lead. The channels through which it may enter into the system are, however, so perfectly familiar to practical chemists, that a few unusual instances of lead-poisoning only need be quoted here.

A cabman suffered from lead colic, traced to his taking the first glass of beer every morning at a certain public-house; the beer standing in the pipes all night, as proved by analysis, was strongly impregnated with lead.[827]

The employment of red lead for repairing the joints of steam pipes has before now caused poisonous symptoms from volatilisation of lead.[828] The use of old painted wood in a baker’s oven, and subsequent adherence of the oxide of lead to the outside of the loaves, has caused the illness of sixty-six people.[829]

Seven persons became affected with lead-poisoning through horse-hair coloured with lead.[830]

The manufacture of American overland cloth creates a white-lead dust, which has caused serious symptoms among the workmen (Dr. G. Johnson). The cleaning of pewter pots,[831] the handling of vulcanised rubber,[832] the wrapping up of various foods in tinfoil,[833] and the fingering of lead counters covered with brine by fishmongers, have all caused accidents in men.

The lead in glass, though in the form of an insoluble silicate, is said to have been dissolved by vinegar and other acid fluids to a dangerous extent. This, however, is hardly well established.[834]

§ 780. Effects of Lead Compounds on Animals.—Orfila and the older school of toxicologists made a number of experiments on the action of sugar of lead and other compounds, but they are of little value for elucidating the physiological or toxic action of lead, because they were, for the most part, made under unnatural conditions, the gullet being ligatured to avoid expulsion of the salt by vomiting. Harnack, in order to avoid the local and corrosive effects of sugar of lead, used an organic compound, viz., plumbic triethyl acetate, which has no local action. Frogs exhibited symptoms after subcutaneous doses of from 2 to 3 mgrms., rabbits after 40 mgrms.; there was increased peristaltic action of the intestines, with spasmodic contraction rising to colic, very often diarrhœa, and death followed through heart paralysis. Dogs given the ethyl compound exhibited nervous symptoms like chorea. Gusserno[835] has also made experiments on animals as to the effects of lead, using lead phosphate, and giving from 1·2 grm. to a rabbit and a dog daily. Rosenstein[836] and Heubel[837] used small doses of acetate, the latter giving dogs daily from ·2 to ·5 grm. The results arrived at by Gusserno were, mainly, that the animals became emaciated, shivered, and had some paralysis of the hinder extremities; while Rosenstein observed towards the end epileptiform convulsions, and Heubel alone saw, in a few of his cases, colic. A considerable number of cattle have been poisoned from time to time with lead, and one instance of this fell under my own observation. A pasture had been manured with refuse from a plumber’s yard, and pieces of paint were in this way strewn about the field in every direction; a herd of fifteen young cattle were placed in the field, and in two or three days they all, without exception, began rapidly to lose condition, and to show peculiar symptoms—diarrhœa, loss of appetite; in two, blindness, the retina presenting an appearance not unlike that seen in Bright’s disease; in three, a sort of delirium. Four died, and showed on post-mortem examination granular conditions of the kidneys, which was the most striking change observable. In the fatal cases, paralysis of the hind extremities, coma, and convulsions preceded death. In another case[838] seven cows and a bull died from eating lead paint; the symptoms were loss of appetite, obstinate constipation, suspension of rumination, dry muffle, quick breathing, and coma. In other cases a marked symptom has been paralysis. Cattle[839] have also several times been poisoned from eating grass which has been splashed by the spray from bullets, as in pastures in the vicinity of rifle butts; here we must allow that the intestinal juices have dissolved the metal, and transformed it into compounds capable of being taken into the system.

§ 781. Effects of Lead Compounds on Man—Acute Poisoning.—Acute poisoning by preparations of lead is not common, and, when it does occur, is seldom fatal. With regard to the common acetate, it would seem that a large single dose is less likely to destroy life than smaller quantities given in divided doses for a considerable period. The symptoms produced by a considerable dose of sugar of lead usually commence within a few minutes; there is immediately a metallic taste, with burning, and a sensation of great dryness in the mouth and throat; vomiting, which occurs usually within fifteen minutes, is in very rare cases delayed from one to two hours. The retching and vomiting are very obstinate, and continue for a long time; the matters thrown up are sometimes streaked with blood; there is pain in the abdomen of a colicky character—a pain relieved by pressure. The bowels are, as a rule, constipated, but occasionally relaxed. The stools at a later date are black from the presence of lead sulphide. The urine, as a rule, is diminished. The breath has a foul odour, and the tongue is coated; the skin is dry, and the pulse small and frequent. The full development of the toxic action is completed by the appearance of various nervous phenomena—headache, shooting pains in the limbs, cramps in the legs, and local numbness. All the symptoms enumerated are not present in each case; the most constant are the vomiting and the colic. If the sufferer is to die, death occurs about the second or third day. If the patient recovers, convalescence may be much retarded, as shown in the case of two girls,[840] who had each swallowed an ounce of lead acetate by mistake, and who suffered even after the lapse of a year from pain and tenderness in the stomach and sickness.

There are “mass-poisonings” by acetate of lead on record, which afford considerable insight into the varying action of this salt on different individuals. A case (e.g.) occurred at Stourbridge in 1840,[841] in which no less than 500 people were poisoned by thirty pounds of lead acetate being accidentally mixed with eighty sacks of flour at a miller’s. The symptoms commenced after a few days; constriction of the throat, cramping and twisting pains round the umbilicus, rigidity of the abdominal muscles, dragging pains at the loins, cramps and paralysis of the lower extremities. There was obstinate constipation; the urine was scanty and of a deep red colour, and the secretions were generally arrested; the pulse was slow and feeble; the countenance depressed, often livid; and the gums showed the usual blue line. The temperature of the skin was low. In only a few cases was there sickness, and in these it soon ceased. It is curious that not one of the 500 cases proved fatal, although some of the victims were extremely ill, and their condition alarming. It was specially observed that, after apparent convalescence, the symptoms, without any obvious cause, suddenly returned, and this even in a more aggravated form. Remittance of this kind is of medico-legal import; it might, for example, be wrongly inferred that a fresh dose had been taken. In the 500 cases there were no inflammatory symptoms; complete recovery took some time. On examining the bread the poison was found so unequally distributed that no idea could be formed as to the actual amount taken.