ARSENIC.

The element (arsenicum)—The oxide (white arsenic)—Arsenicum—Arsenicum trioxide. Forms of: (1) Crystalline—(2) Amorphous—Solubility. Uses and occurrences: (1) Steeping wheat—(2) Preservation of skins—(3) Antiseptics—(4) Glass making—(5) Fur in boilers—(6) Candles—(7) Preservation of wood—(8) Sheep washes—(9) Scheele’s green and emerald green as pigments in sweets (case of Franklin and Randall), wall papers, toys, &c.—(10) Medicinal—(11) For horses—(12) Tooth-stopping—(13) Aniline dyes—(14) Fireworks—(15) Rat and fly poisons (case of Maria Gage)—(16) For cleansing metals—(17) Arsenic eaters—(18) Cosmetics—(19) For bronzing metals—(20) Beer brewed from glucose—(21) American paper collars—(22) Speculum metal—(23) Inhalation for asthma and bronchitis—(24) Mineral waters. Sulphides of Arsenic: (1) Orpiment (case of M. A. Burdock)—(2) Realgar. Arsenic acid—The arsenates—Arsenic trichloride—Arseniuretted hydrogen—Methods of extraction—Tests—Modifications of old processes suggested—Marsh’s test, distinction of results in arsenic and antimony—Reinsch’s test—Doses—Antidotes—Physiological effects—Remarks—Did L’Angelier commit suicide?

The name “arsenic” is applied to two things: in chemistry it means the element As; in popular usage it signifies the oxide As₂O₃. In our report, the element will be called arsenicum, the oxide simply “arsenic” or “white arsenic.”

ARSENICUM,

Symbol As, is an element of steely metallic lustre, tarnishing to dull dark grey, met with in crystalline (rhombohedral) fragments, so brittle that they can be easily reduced to a dark grey powder, insoluble in water, but slowly absorbing oxygen and dissolving, insoluble in pure hydrochloric and in vegetal acids, and in alcohol, soluble (by oxidation) in strong sulphuric and in nitric acid, in chlorine, in solution of bleaching powder. Tasteless, and inodorous until heated, when it sublimes, without melting, at 110° C. (Guy), and gives a strong odour of garlic. Sp. gr. 5·8. The characters of the metal are utilized in Marsh’s and other tests, hereafter described. Heated in air, it oxidizes to white fumes of As₂O₃. It is employed chiefly to harden lead in making shot, in the proportion of 0·3 per cent. The use of these in cleaning bottles, &c., may contribute a trace of As: the presence of a larger amount of lead would in this case indicate the source. Common Britannia metal, used for teapots, spoons, &c., often contains As. It occurs also in many minerals.

When oxidized it is poisonous, but pure arsenicum passes through the body of animals unaltered (Wagner’s Chem. Technology, trans, by Crookes, 1872, p. 86). The vapour is very poisonous.

Arsenicum has two oxides, the trioxide and the pentoxide.

ARSENICUM TRIOXIDE.

Synonyms.—Arsenious oxide, arsenious acid, arsenious anhydride; popularly, “arsenic,” “flour of arsenic,” or “white arsenic:” in mining districts it is sometimes called “mercury:” Latin, acidum arseniosum.

Chemical formula As₂O₃, or two atoms (150 parts by weight) of arsenicum, to three atoms (48 parts by weight) of oxygen.

Forms.—(1.) Crystalline. By sublimation and slow condensation on moderately heated surfaces, also by deposition from solution, we obtain regular octahedra, often so modified as to appear like equilateral triangular or hexagonal plates, or even elongated into triangular prisms, but never in the form of regular tetrahedra such as tartar emetic yields. For figures, see Guy and Ferrier’s Forens. Med., 1881, pp. 440 and 670. The crystals are transparent and highly refracting. Sp. gr. 3·69. Volatilizes without melting, except under increased pressure.

(2.) Amorphous or vitreous. Suddenly cooled, As₂O₃ condenses as clear transparent drops, finally cohering into a glassy mass, sp. gr. 3·74. When kept, this becomes opaque, perhaps owing to a change into the crystalline variety, constituting the “porcellanous” form found in commerce. If the lumps be broken, layers of still transparent As₂O₃ will be seen.

The solubility depends on the variety, temperature, length of time it is digested, fineness of powder, &c. So that exact figures cannot be given, as hardly two authorities agree. It is certain, however, that the amorphous form is less soluble than the crystalline.[131] The accepted statement is that given by Taylor (Med. Juris. 1, 250): that digested with cold water, from ¹/₅₀₀ to ¹/₁₀₀₀ dissolves, equal from one half to one grain per fluid ounce; if boiled for an hour and allowed to cool, an average of twelve grains per fluid ounce remains in solution; if boiled for a shorter time, less is dissolved. See also Woodman and Tidy’s Forens. Med., 1877, pp. 133, 134. Organic matter is said to decrease its solubility; I have not found that it does so to any notable extent. Dr. Blondlot (Med. Times and Gazette, Feb. 11, 1860) states that fats, such as bacon, diminish the solubility; this must be by coating the particles and preventing contact with water. Powdered white arsenic in all cases refuses for a long time to become moistened by water, floating on the top, and collecting in little lumps as if greasy: the appearance is so peculiar as to have led sometimes to its detection. Commercial powdered white arsenic is generally the opaque form pulverized, but it may be crystalline.

As₂O₃ is very soluble in potash and soda and their carbonates, forming arsenites. It is less soluble in ammonia. In hydrochloric acid it dissolves easily, forming chloride of arsenic. It is less soluble (1 in 2,000) in alcohol than in water. One part dissolves in 200,000 of chloroform. It is insoluble in pure ether. It is heavy to feel, tasteless, very faintly acid to test paper, and so feeble in affinity that its soluble salts are strongly alkaline, and are decomposed by all acids with separation of As₂O₃. The powder and its vapour are inodorous, but when heated with charcoal or organic matter it is reduced to arsenicum, with its odour of garlic.

Uses and Occurrence.—1. As a preservative against insects and fungi, for steeping seed-wheat. Many accidents have resulted. Birds poisoned by it and afterwards eaten by man have occasioned severe symptoms. From 1830 to 1840 in France 235 accusations of arsenic poisoning occurred, of which 110 were against agricultural persons, proving that the use of the drug in farming gives dangerous facilities for crime. Sulphate of copper, or, better, a mixture of sulphate of soda and lime, are more effectual as preservatives, and the latter mixture is not poisonous. (Lancet, 1849, Jan. 20.)

2. For preserving skins and furs (arsenical soap). This use has also caused serious results in the operators. Stuffed birds, &c., kept in living rooms may prejudicially affect the inmates by giving off arsenical dust.

3. As an antiseptic it is injected in solution through the vessels of subjects for dissection. Of course in this case the body would show signs of the anatomical examination it had undergone. In the trial of Professor Webster for the murder of Dr. Parkman, at Boston, U.S., March, 1850, the absence of arsenic and other preservative substances in the corpse proved that it had not been a subject for dissection.

4. In glass making and the production of opaque white enamels. Here most of the vapour passes up the chimney and is diffused.

5. Some of the patent preparations for preventing “fur” in boilers have contained alkaline arsenites.

6. Formerly wicks of candles were steeped in arsenic solution to prevent a long “snuff” forming. Moreover, it was incorporated with the candle itself to improve its appearance. The result was a constant diffusion of arsenic vapour in the room. Tapers were also coloured with emerald green (copper aceto-arsenite), which likewise gave rise to arsenical fumes. These objectionable practices have been fortunately given up, owing to the strong representations of scientific men.

7. Wood is sometimes preserved by a solution of arsenic, and then tarred. This use would be practically free from danger, except to the operatives.

8. An alkaline arsenite is used for washing sheep to destroy vermin. The workmen sometimes suffer. (Lancet, 1857, p. 281.) Streams have been poisoned, the solution has been drunk in mistake (Ibid, 1856, p. 447), and lastly, the sheep themselves have been killed (Taylor’s Med. Juris., i. 272). Carbolic acid would probably answer better.

9. Cupric arsenite (Scheele’s green) and aceto-arsenite (Schweinfurth or emerald green) are used as pigments. In one case, where a baker’s shelves had been painted with this colour, emerald green was found adhering to the bottoms of the loaves (Med. Times and Gaz., 1854, p. 326). Blancmange (R. v. Franklin & Randall, Northampton, 1848[132]), ornaments on cakes (Lancet, 1849, Feb. 17th), sweets, dresses, and artificial flowers (Husemann, Jahresbericht, 1872, p. 480), lamp-shades, insides of pasteboard cigar-holders, toys,[133] wrappings for chocolate, &c., wafers, water and oil colours, and wall papers have all been coloured with emerald green. Whenever such things have been swallowed, the green colour is seen in the vomit. Boxes of paints should never be given to young children. Cakes of emerald green and of other poisonous colours have often been sucked or eaten with fatal result; they are the more tempting as they are generally made up with honey or glycerine. Bright green wall papers have gone out of fashion, still many of the dull colours have emerald green in their composition. Such papers certainly give off arsenical dust, even if they do not evolve arseniuretted hydrogen or other arsenical gas, and the symptoms they produce have been well authenticated. In a new house the papers should always be tested. Messrs. Woollams, of Marylebone Lane, were, I believe, the first to disuse arsenical pigments in paper-hangings.

These arsenites of copper give, with a little ammonia, a blue solution (due to the copper), in which a crystal of silver nitrate becomes covered with a yellow coating of silver arsenite. The As can also be easily found by the other tests.

Dr. Raseden of Mersberg finds that arsenical papers cause rheumatic pains, neuralgia, cough, lassitude, and emaciation (Lancet, 1849, April 7th). They also cause skin eruptions. These effects disappear when the patients are removed. In Germany the use of these pigments is prohibited; it should be so in England. Unfortunately no other permanent green colour is so bright in tint.

The copper arsenites are insoluble in water, but soluble in acids, hence are dissolved by the gastric juice, and then absorbed.

10. In medicine, arsenic is used for skin diseases, ague, and as a tonic; externally for cancer and lupus. Liquor arsenicalis B.P., Fowler’s solution, or “ague drops,” is composed of arsenic 80 grains, potass, carbonate 80 grains, water 1 pint, flavoured with lavender. It is a solution of potassium arsenite. Liquor arsenici hydrochloricus is arsenic dissolved in hydrochloric acid, giving arsenic trichloride, of the same strength as liquor arsenicalis. Among unofficial preparations are “Donovan’s Solution of Arsenic,” containing mercuric and arsenious iodides; strength 0·69 grain arsenicum per fluid ounce: “Davidson’s Cancer Remedy” equal parts of arsenic and hemlock (Dr. Paris): “Cancer Paste,” containing 8 per cent. of arsenic, with cinnabar and dragon’s blood: “Hydrophobia Pill,” ¹/₁₆ to ¹/₁₂ grain arsenic, with 1 grain pepper, an absurd remedy much used in the East Indies. (Blyth’s Pract. Chem., 1879, p. 376.) The pharmacopoeial preparations of arsenic acid will be described under arsenic pentoxide.

11. It is given by grooms to horses, to render their coats sleek, and improve their wind, under the name of “condition balls or powders” (strength 2½ to 5 per cent. of arsenic), also for worms, and as a tonic.

12. For destroying the nerves of decayed teeth, about ¹/₂₅ grain is placed in the cavity. In the Lancet a case is recorded in which inflammation and caries of the jaw followed this practice, which is a very dangerous one.

13. In the manufacture of some aniline dyes, and in the reduction of indigo, arsenic is often used. Dyed stockings, &c., have caused skin irritation, supposed to be due to arsenic, but more probably owing to the dye itself.

14. Firework preparations commonly contain some compound of As, and therefore give poisonous vapours. “Bengal light” consists of 24 of potass. nitrate, 7 of sulphur, and 2 of realgar (arsenic disulphide). See also Blyth, Prac. Chem., p. 379.

15. Rat Poisons:—No. 1. Arsenic 6 per cent., made into a paste, with equal parts of flour and suet, variously coloured and scented. No. 2. Equal parts of arsenic and carbonate of barium (itself poisonous), coloured with rose pink, and scented with oils of anise and rhodium.[134]

Fly Poisons.—“Fly powder,” a grey mixture of As and As₂ O₃. “Fly water,” a solution of arsenious acid, or arsenite of soda or potash, of varying strength, sweetened with sugar, treacle, or honey. (Med. Times and Gazette, Sept. 13th, 1851.) Some also contain orpiment (arsenic trisulphide).

16. For cleansing metals, arsenite of soda has been used on account of its strong alkalinity. It is an absurd preparation to use for this purpose, as washing soda or potash would act better. In December, 1857, 340 children were poisoned by water from a boiler that had been “cleaned” by this compound (Taylor on Poisons, 2nd ed., p. 378). In 1863, a man died from drinking beer out of a pot which had been thus cleansed (Taylor, Med. Juris., 1, 273).

17. The well-known “arsenic eating” of Styria has been ridiculed as impossible, but has yet been authenticated on further examination. A Styrian wood-cutter was seen by a medical man to eat a piece of arsenic weighing 4½ grains, and next day another 5½ grains, yet remaining in his usual health. It is also eaten by the natives of Ceylon (Med. Times and Gaz. 1862, p. 454, and 1866, p. 375). Workmen in arsenic factories often become habituated to its influence. See a paper by Roscoe, Mem. of Lit. and Phil. Soc. of Manchester, 1860. I myself can testify to this fact. A student in the College of Science, Dublin, was accustomed to take out of the arsenic bottle little lumps about 3 or 4 grains each and eat them, without apparent ill effect.

18. As a cosmetic, applied externally, it would probably be useless. Unless the skin were abraded, or it remained very long in contact, no absorption, and hence no poisonous effect, would result, but any scratch or wound would be dangerous. (See Christison’s Evidence, case of Madeline Smith, p. 320.) And if in protracted contact with the skin, it will cause symptoms. (Memoirs of Lond. Med. Soc., ii., 397, Amer. J. of Med. Science, July, 1851.)

19. A solution of chloride of arsenic has been employed for “bronzing” metals. The fumes would be highly pernicious.

20. Ritter, of Rouen, states that glucose or starch-sugar frequently contains arsenic, derived from the sulphuric acid employed in its manufacture being made from arsenical pyrites. He finds that by this means the arsenic is introduced into beer brewed with glucose, into confectionery, syrups, liqueurs, &c. (Reimann’s FÄrber Zeitung, No. 3, 1878.)

21. It is said that certain paper collars and cuffs which are extensively made in America have proved poisonous from containing a considerable proportion of arsenic. (Les Mondes, Nov. 11th, 1880.)[135]

22. Speculum Metal, for telescope mirrors, is an alloy of copper, tin, and 3 per cent. of arsenic.

23. In America, a paper soaked in a solution of arsenic and other drugs is burnt, and the smoke inhaled for asthma and bronchitis. (Year Book of Pharm., 1873, p. 345.)

24. Traces occur in mineral waters.

SULPHIDES OF ARSENIC.

Orpiment, As₂S₃, Auripigmentum, or King’s Yellow, trisulphide of arsenic, obtained by precipitating a solution of arsenic with sulphuretted hydrogen, is a yellow inodorous powder, insoluble in water and in hydrochloric acid, but slowly oxidizing in air to arsenious acid, and therefore poisonous. It is found native. By heat it melts to a reddish liquid: if air be excluded, it volatilizes at about 700° C., and condenses unchanged: if air be present, it is oxidized to sulphur dioxide and arsenic trioxide, which condenses in the crystals before-mentioned. It is soluble in alkalies and their carbonates, and reprecipitated by hydrochloric acid. Commercial “King’s Yellow,” formerly used as a pigment, but now replaced by Chromate of lead, is a very poisonous mixture of As₂ O₃ and As₂ S₃. It is sometimes employed in printing indigo. A mixture of orpiment, water and lime is used in the East as “Rasma” (see page 320) for a depilatory. In a corpse, by putrefaction, the arsenic is frequently converted into sulphide.

Realgar, the disulphide, As₂ S₂, is red, exists as a mineral, and is also made artificially for fireworks. It contains about 75 per cent. of arsenic, but varies. Formerly it was used as a pigment, and in tanning to remove hair.

These sulphides have rarely been used for criminal purposes. Orpiment was employed by Mary Ann Burdock, 1833.[136] Being insoluble, they would only be absorbed after oxidation into As₂ O₃. Ossikovszky (J. Pract. Chem. 2, xxii., 323) finds that this change happens rapidly in contact with organic bodies. But the opposite change, by putrefaction and development of sulphuretted hydrogen, of As₂ O₃ into As₂ S₃, is far more likely and frequent.

ARSENIC ACID

is obtained by oxidizing As₂ O₃ by nitric acid. It is a white deliquescent solid, inodorous, very soluble in water to a syrupy solution, which is corrosive, strongly acid and metallic in taste. By heat it first gives the pentoxide, As₂ O₅, then it breaks up into As₂ O₃ and oxygen, finally completely volatilizing. It is said to be less poisonous than As₂ O₃. (WÖhler and Frehrichs, Ann. Chem. Pharm., lxv., 335.)

The arsenates are very like the phosphates. Like them they give with acid molybdate solution a yellow, with magnesium sulphate a white crystalline, precipitate. But with sulphuretted hydrogen, after acidifying, they give slowly a yellow precipitate of sulphide of arsenic and sulphur; and with silver nitrate a liver brown precipitate of silver arsenate.[137] Sulphurous acid reduces arsenic acid to arsenious.

Sodium arsenate is in the British Pharmacopoeia, and is employed in calico printing. A brominated solution of potassium arsenate (strength = 1 per cent. As₂ O₃) is used in Russia for epilepsy. “Pearson’s solution” is 1 grain sodium arsenate to 1 oz. water. “Macquir’s neutral arsenical salt” is a binarsenate of soda. “Papier Moure” consists of paper soaked in solution of potassium arsenate (Tidy).

Fischer (Ber. deutsch. Chem. Gesellschaft, xiii., p. 1778) proposes ferrous chloride as better than sulphurous acid for reducing arsenic acid to arsenious (see process for separation, post).

Arsenic Trichloride, As Cl₃, is a volatile, colourless liquid, very pungent, and fuming in air. It has been discarded from medical use on account of its dangerous properties. A case of poisoning by it is mentioned in Taylor (Med. Juris. 1, p. 278). It is obtained in the process for separation from the organs. Arsenic Triiodide, a dull red crystalline solid, is used in ointments.

Arseniuretted hydrogen, As H₃, is a colourless gas of a garlic odour, almost insoluble in water. It burns with a livid bluish-grey flame, forming water and a white cloud of As₂ O₃. By heating to redness it is decomposed into hydrogen and a deposit of arsenicum (the “mirror”). It is formed whenever hydrogen is evolved in contact with arsenic compounds, hence has caused accidents in making hydrogen from impure zinc. It is probably the most deadly compound of As, and proved fatal to its investigator, Gehlen, and in several other cases.

EXTRACTION AND TESTS.

If arsenic has been given in the solid form, the greater part will remain insoluble, and will be found either in lumps or powder in the stomach, or as a white powder adhering to its lining. Any substance so found should be washed with water and tested for arsenic. It is absurd to say, as Dr. Letheby did in Ann Merritt’s case (ante, p. 366), that the quantity was too small for examination: if a white powder can be seen, it can be tested. In the contents, or in any fluid food, the heaviness of powdered arsenic will cause it to readily separate as a sediment. Soot or indigo, the legal admixtures, should also be sought.

Arsenic is not naturally present in the body (Sonnenschein, Gerichtlich. Chemie, p. 122; and others). As it occurs in soils, in cases of disinterment a portion of the earth surrounding the coffin should be tested.[138]

When absorbed, it may pass into every part of the body, but more especially into the liver and spleen. De Poncy and Livon have supposed that it was capable of replacing phosphorus in the actual brain substance (Comptes Rendus, 23, June 9th, 1879), and that it is mainly localized in the brain. Another author finds it concentrated in the bones. Prof. E. Ludwig of Vienna, in the case of a woman who suffered from making artificial flowers coloured with magenta containing arsenic, found arsenic in the liver, spleen, kidneys, and stomach, but not in the bones or urine (Lond. Med. Record, Dec. 15th, 1877, p. 509). He found also that in human beings as well as dogs poisoned with arsenic, in both acute and chronic cases, the liver contained the largest amount, the kidneys sometimes a considerable quantity, and the bones, brain and urine, only small traces (Jahresb. fÜr Thierchemie, 1879, 85). These results have been discussed by Johnson and Chittenden (American Chem. Journal, 2, 332), who, in a woman poisoned by arsenic, found, a year and a half after burial, over 5 grains of As₂ O₃, almost evenly distributed. The conclusion to be drawn is, that, of the absorbed arsenic, the main part will be in the liver, and the rest in varying proportions in other tissues, so that as much as possible of the whole body should be examined.

As the large quantity of organic matter is in the way of the tests, it has been proposed to get rid of this by different processes. That of Fresenius and V. Babo consists in oxidizing the substances by strong hydrochloric acid and chlorate of potash. There is a great objection to this, as loss is liable to occur from volatilization of arsenic trichloride, unless it is done in a retort, which is practically impossible on account of the bulk and frothing, and the danger of explosion from the oxides of chlorine formed.

The following modification of an old process has been found by the author to be satisfactory. It may be used also for antimony and mercury. Weigh the whole, cut up finely, and grind the matters to a pulp with water, reserving a weighed portion of about one third; render strongly alkaline with potash or soda previously tested for arsenic. Pass in a current of chlorine, stopping before the alkalinity is destroyed. Boil the solution down to a low bulk, not to dryness, till a portion taken out and treated with acetic acid gives no chlorinous odour, showing that the hypochlorite has been completely decomposed. Arsenic trichloride does not escape from alkaline solutions, so there is no loss. Add sufficient pure aqueous sulphurous acid, to reduce the arsenic acid to arsenious. Now transfer to a large retort provided with a tube-funnel and condenser, the end dipping into water in a well-cooled tubulated receiver, itself connected by a tube with a flask containing dilute potash solution. Through the tube-funnel pour in pure concent. sulphuric acid in volume about equal to the liquid, adding it gradually, as there is much heat and effervescence. Mix well by shaking, and distil slowly from a sand bath. In distilling a moderately strong solution of mixed arsenious and antimonious chlorides in concent. hydrochloric acid, I have found that the arsenic all comes over in the first third of the distillate, and that after two-thirds have passed over, the antimony also begins to distil. Hence, in the above process the distillation should not be carried beyond half the volume of the liquid in the retort, when all the arsenic, in whatever form it originally existed, will be found as chloride in the receiver, except a little which may have escaped into the potash. Test a portion of the potash solution by Marsh’s or Reinsch’s process as hereafter described: if any arsenic be present, add the remainder to the liquid in the receiver, taking care that excess of free acid is left. Pass into the distillate washed sulphuretted hydrogen in excess (or add a solution of the gas in water), warm, cover, and allow to stand. (The excess of sulphuretted hydrogen may afterwards be removed by warming and passing in carbonic acid gas.) If any arsenic be present, a yellow precipitate of arsenious sulphide, As₂S₃, will appear; if the precipitate be pale, it will consist mainly of sulphur, formed by the action of the sulphuretted hydrogen on the sulphurous acid which is present. Some organic matters are also generally present. Collect the precipitate on a filter, wash with sulphuretted hydrogen water, dissolve in a dilute solution of ammonium carbonate, and again precipitate with hydrochloric acid. The precipitated arsenious sulphide is now nearly pure: it may be collected on a small filter, washed rapidly, again dissolved in ammonia, the solution received in a porcelain dish, evaporated to a low bulk, transferred to a weighed porcelain boat, and heated cautiously in a current of carbon dioxide to a temperature not above 400° C., sufficient, in fact, just to melt the arsenious sulphide. [Sulphur boils at 446° C., As₂S₃ at 700° C.] Any remaining sulphur is thus removed, and the arsenious sulphide may then be weighed. The weight multiplied by 0·805 gives the amount of arsenic trioxide.

A less preferable way is to collect the arsenious sulphide on a weighed filter, to dry, and dissolve out any sulphur by carbon disulphide. Yet another method is to oxidize by nitric acid, evaporate, precipitate the arsenic acid by a mixture of ammonic chloride, magnesic sulphate, and strong ammonia —“magnesia mixture”) as ammonio-magnesic arsenate, and weigh, either as that salt, or, after ignition, as pyroarsenate of magnesia. The former, dried at 100° C., contains 39·57, the latter 48·29 per cent. of As. Lastly, if the sulphide, oxidized by nitric acid, be alkalized with ammonia, and warmed to 70° or 80° C. with a solution of ammonium molybdate in nitric acid, as used for the ordinary determination of phosphates (see Fresenius, Qual. Anal., p. 54), a yellow precipitate of arsenomolybdate of ammonia appears, which can be weighed: it contains 3·3 per cent. of As (Bull. Soc. Chem., Jan. 7th, 1877).

But where such importance may hang on quantities, the use of weighed filters for such small amounts is simply courting error. When the As₂S₃ has been weighed in the porcelain boat, calculate it into As₂O₃, or into As (it contains 61 per per cent. of As), then cover it with a mixture of pure potassic cyanide and sodium carbonate, place it in a piece of combustion tubing drawn out at the end into a long thin point, pass washed dry carbon dioxide over it, and heat cautiously till all the water is expelled. Finally raise the temperature to full redness, and pass a slow continuous current of the gas, keeping the narrow part of the tube cool with moistened blotting paper. The sulphide will be reduced to As, which will deposit in a metallic coating on the narrow portion. Seal this part, and preserve it as evidence.

It is obvious that the residue in the retort may be tested for other metals.

The presence of arsenic ascertained, and the quantity known, it would seem as if nothing more was necessary. Still, it is useful to confirm results by the other tests. The reserved portion may now be divided and used as follows:—

MARSH’S TEST.

If hydrogen be evolved in presence of arsenical compounds, it combines with the element to form “arseniuretted hydrogen,” or arsine, AsH₃, a colourless gas of alliaceous odour, extremely poisonous, giving, when passed into silver nitrate solution, a precipitate of silver and a solution of As₂O₃; decomposed at a red heat into As and hydrogen, and burning with a livid flame into As₂O₃ and water. The flame yields, when a cold surface, such as a porcelain crucible-lid or dish, is depressed into it, a steel-grey lustrous stain or ring of metallic arsenic.

To evolve the hydrogen, Marsh originally used zinc and sulphuric acid. As it is so difficult to obtain zinc pure, magnesium has been proposed. But the evolution is then too rapid. Moreover, the reputed “pure” acids of commerce are scarcely ever free from a trace of arsenic. This difficulty affects equally the galvanic method. Hence it is better to employ sodium amalgam (Edmund Davy, Chem. News, xxxiii., 58, and ditto, 94). One part of sodium, scraped free from oxide, is melted under solid paraffin, and gradually added to ten parts of mercury (previously purified by nitric acid) with constant stirring, the paraffin poured off, and the amalgam cleaned by washing with pure dry benzine. The result is a solid crystalline alloy.

A few fragments of this alloy are placed with water in a flask provided with a thistle funnel, and with a delivery tube dipping into a 4 per cent. solution of silver nitrate. The horizontal part of the delivery tube is heated to just below redness by a lamp, meanwhile being supported to prevent its bending. If, after about an hour, no As ring appears in the tube, and if the silver nitrate, after precipitation of the silver by hydrochloric acid and filtration, gives no arsenious sulphide on addition of sulphuretted hydrogen, the amalgam is pure. Now add to the flask the suspected liquid, put in more amalgam, and continue the heating of the tube and passing of the hydrogen till no further evolution of As occurs. The portion of tube containing the deposit of As may be cut off, weighed, the As dissolved off by aqua regia, and the tube washed, dried, and weighed again. The silver nitrate solution contains the remainder of the As dissolved as As₂O₃: after removal of the silver by hydrochloric acid and filtration, the arsenious acid solution may be divided, a portion titrated by iodine (see Blyth’s Pract. Chem., p. 392), and the rest tested qualitatively by sulphuretted hydrogen, ammonio-silver nitrate, and ammonio-cupric sulphate (see these tests, post).

If the original liquid be rendered strongly alkaline before adding the amalgam, no antimony will pass off with the arsenic. But from acid liquids, arsenic and antimony pass off together. They both give metallic rings in the tube, and stains on a cold surface. The chief distinctions between them are as follows:—

1. Arsenic.—More volatile, hence deposited further from the flame; bounded by a “hair brown” fringe of suboxide; heated in a current of sulphuretted hydrogen gives yellow As₂S₃, unchanged by passing dry hydrochloric acid gas: heated in air, it gives easily a sublimate of As₂O₃ in glistening octahedral crystals. It is soluble at once in chloride of lime solution.

2. Antimony.—Less volatile, hence forming close to the flame; no brown fringe; heated in a current of sulphuretted hydrogen, gives orange or black Sb₂S₃, volatilized by passing dry hydrochloric acid; heated in air, it gives a white oxide, volatile with great difficulty, and not generally crystalline. It is insoluble in chloride of lime solution.

By the above process, Edmund Davy has detected one-millionth of a grain of As; ¹/₁₀₀₀ grain gives a very decided effect in a few minutes. It is applicable not only to As₂O₃, but to all other arsenical compounds in powder, whether soluble or insoluble. Organic matter interferes very little.

It must be observed that hydrogen alone may give a slight reduction and precipitate in solutions of silver nitrate.

To prepare pure sulphuric acid and pure zinc, see Selmi, Chem. Soc. Journal, May, 1881, p. 311.

REINSCH’S TEST.

If a fragment of pure copper be boiled with pure hydrochloric acid for ten minutes, no discolouration occurs. If now a solution containing arsenic be added, the copper turns black or grey, from formation of an alloy of copper and arsenicum. On drying the copper, and heating it in a small glass tube closed at one end, the arsenicum is oxidized, with production of crystals of As₂ O₃. Organic matter does not interfere. Antimony, sulphides, and some metals produce a similar grey deposit, but do not yield a crystalline sublimate. Mercury also precipitates on the copper, but the sublimate consists of metallic globules.

Any compound of arsenicum, mixed with dried potassium cyanide and carbonate of soda, introduced into a piece of hard glass tubing drawn to a point, and heated in a slow stream of dry carbon dioxide, gives a deposit, in the narrow portion, of the whole of its arsenic in the metallic form (Fresenius).

As₂ O₃ heated in a tube with dry potassium or sodium acetate gives cacodyl-oxide (Bunsen) of an exceedingly offensive alliaceous odour.

In solution, arsenious acid gives:—

1. With ammonio-silver nitrate (prepared by adding silver nitrate to dilute ammonia till a precipitate just forms) a yellow precipitate of silver arsenite, soluble in ammonia and in nitric acid.

2. With ammonio-cupric sulphate (prepared by similarly treating cupric sulphate), a bright green precipitate of cupric arsenite.

3. With sulphuretted hydrogen a yellow colour (the intensity of this has been proposed as a method of estimating small quantities of arsenic by comparison À la Nessler), but no precipitate till hydrochloric or other acid be added, when yellow arsenious sulphide falls. This is a most delicate test, as arsenious sulphide is only soluble to the extent of one part in one million of water (Fresenius, Quant. Anal. p. 137), and not much more soluble in acids. The precipitate may be weighed, or treated as already mentioned (pp. 386-7). Tin and cadmium solutions also give yellow sulphides, but they are insoluble in ammonia, and do not yield the other tests.

4. Stannous chloride (protochloride of tin) gives a brown deposit of metallic arsenic. With acids containing traces of arsenic it gives a brown colour.

DOSES.

1. Medicinal (British Pharmacopoeia).—Acidum arseniosum (As₂ O₃), ¹/₆₀ to ¹/₁₂ grain in solution. Liquor arsenicalis (solution of potassium arsenite), 2 to 8 minims. Liquor arsenicalis hydrochloricus (solution of chloride of arsenic), 2 to 8 minims. SodÆ arsenias (sodium arsenate), ¹/₁₆ to ? grain. Liquor sodÆ arseniatis (solution of the preceding), 5 to 10 minims. Ferri arsenias (ferric arsenate), ¹/₁₆ to ½ grain.

2. Poisonous.—Smallest recorded: one grain, (Lancet, Dec. 16th, 1837), two grains, (Provincial Journal, 1848, p. 347); average smallest, 2½ grains. Recoveries have been described after enormous doses, up to 1½ ounce, taken solid and therefore not dissolved, rejected by vomiting or purging, or prevented from irritant action by abundance of food (see a case in the Lancet, Jan. 13th, 1849, when 1oz. was taken with recovery).[139]

Idiosyncrasy may cause smaller doses to be dangerous; on the other hand, habit may cause tolerance of the poison, as already mentioned with regard to arsenic eaters. Nitre is said to increase the poisonous action (Med. Times, 1844, p. 216). Antimony by its prostrating action would have the same effect.

PHYSIOLOGICAL EFFECTS.

The symptoms usually commence in ½ to 1 hour after administration (Taylor), but vary with dose, form, &c. They have also been immediate (case of Lofthouse, York, 1835); in ten minutes (Guy and Ferrier); in ¼ hour (Taylor); in 5, 7, 8, and 10 hours (Med. Gaz. xlvii. 722); in 23 hours (Med. Times, Oct. 21, 1848); in four days (Woodman and Tidy, Forens. Med. p. 134).

As to the character of the symptoms, irritation of the stomach and intestines is the main feature. Burning pain, vomiting and purging, cramps and occasionally tetanus (Orfila, i., 449) occur. Rarely there is insensibility and no pain. Great thirst, constriction of the throat, headache, and finally exhaustion are common. Sometimes epilepsy or paralysis has been caused. The truth is, that every variety of constitutional disturbance may be caused by the violent irritation of the alimentary canal, except that the intellect is rarely affected. In many cases the effects closely resemble those of acute diarrhoea or English Cholera. One anomalous case is on record when death occurred in four hours after sound sleep, and no inflammation of the stomach was found (Lancet, xii., 194). For a detailed list of cases, see Guy and Ferrier’s Forens. Med. p. 457.

Fatal period.—Shortest, twenty minutes (Taylor); average, about twenty-four hours. Death in three to eight hours is common. But the end has been sometimes far more protracted, even to two years (Ibid., Med. Jur. i., 256).

The vomit is usually yellowish (L’Angelier) from bile: occasionally it is tinged with blood; rarely white. If the arsenic has been mixed with soot or indigo, these will affect its colour.

Post Mortem Appearances.—The lining membrane of the stomach and intestines is almost always inflamed and reddened, rarely darker from congestion. White patches, covered with mucus, should be examined for solid arsenic. Perforation, ulceration, and gangrene are rare. In bodies long buried, the arsenic is often converted into sulphide by putrefaction, and then appears as a yellow coating. Occasionally inflammatory appearances are found in the mouth, throat and other organs. Congestion of the brain is uncommon.

Among the effects of chronic poisoning by arsenic may be noted inflammation of the eyelids (conjunctivitis), skin eruptions, irritability of the stomach, jaundice, and local paralysis (for cases see Taylor’s Med. Jur., i. 252).

TREATMENT AND ANTIDOTES.

Vomiting should be encouraged by emetics or tickling the throat; the stomach pump being used if judicious. To obviate the irritation, demulcents such as arrowroot, mucilage, &c., are useful. Albumen (white of egg) has proved serviceable (Lancet, Jan. 13th, 1849). To render the arsenic insoluble, magnesia or chalk may be given. But the best chemical antidote is hydrated ferric oxide, freshly prepared by precipitating ferric chloride or tinct. ferri sesquichlor. with carbonate of soda (washing soda), or by similarly precipitating ferrous sulphate (copperas), and then shaking the mixture with air till it turns red, or by the following formula:—

(Hoglan, Year Book of Pharm. 1881, p. 211).

M. Lucas of Beauvais has stated, that in nine cases of arsenical poisoning, calcined magnesia arrested the symptoms and eventually removed the effects (J. Chim. Medi. 1850).

REMARKS.

Arsenic has been given in pessaries by the vagina, in ointment for skin diseases and by “cancer doctors,” also inhaled as vapour for asthma, in each case with dangerous result.

The frequent occurrence of this poison in common articles of use gives an opportunity to the defence which has led to analyses of multitudes of articles—wall-papers, clothing, cooking vessels, &c. It may be positively affirmed that if white arsenic in the solid state be found in the stomach, it could not have come from any of these sources. The trace that could be derived from wall-papers would be infinitesimal. The tests for arsenic are almost inconveniently delicate, so that the slightest impurity of the reagents will make it appear to be present. Reichardt (Archiv. der Pharm., xiv. 1-23), states that ¹/₁₀₀₀ milligramme of As₂O₃ evolved as arseniuretted hydrogen will precipitate silver nitrate, and that by this means he has found it in the urine of patients suffering from arsenical wall-papers. The effect of such papers is certainly pernicious, though it may be mentioned that in Silesia mortar is made with arsenical sand, and people living in houses thus built do not suffer (Lancet, 1849, April 7th). On the whole it may be concluded that in a trial, traces of arsenic will not be sufficient, a tangible quantity found and weighed will be the only sufficient evidence of poisoning by the mouth.

To illustrate the value of a knowledge of chemistry to a medical man in such cases the following may be quoted. A child of ten was supposed to have eaten a quantity of meal mixed with arsenic for rats. An emetic of sulphate of zinc was given: the first vomit gave with ammon. sulphate of copper a bright green, with ammon. nitrate of silver, a yellow precipitate, thus establishing that the poison was arsenic. Emetics and diluents were continued, then albumen was given. Some hydrated ferric oxide was hurriedly made from common green vitriol (ferrous sulphate) and ammonia: the washed precipitate was administered in successive teaspoonfuls. Recovery on the third day. In the vomit 10 grains of white arsenic were found. (Lancet, 1849, p. 311.)

The following is a curious form of attempted poisoning. A person lately presented this prescription in Paris: “Decoct. barley, 8 oz.; hydroch. acid, 1 drachm; arsenious acid, 10 grains.” The signature of a physician was appended, but, on suspicion being aroused, was found to be a forgery.

In Ann Merritt’s case, Dr. Letheby stated that arsenic had been taken not more than two or three hours (afterwards he said four) before death, because he found undigested gruel in the stomach, containing arsenic in solution, and because the intestines contained very little arsenic. This conclusion was considered by weighty authorities to be rash, and probably wrong, because:—

1. He found 2 grains (a poisonous dose) in the liver. This could hardly have got there within so short a time.

2. In a stomach irritated by arsenic or disease, food may remain undigested for seven, eight, or more hours.

8. A previous dose of arsenic, adherent to the coats of the stomach, might be dissolved by an influx of warm gruel.

4. The portion in the intestines might have been evacuated by purging.

5. The “pinkish liquid” described by the surgeon who performed the post-mortem, pointed to admixture with blood, therefore to inflammation of some standing, and certainly did not tally with Dr. Letheby’s description of “gruel.”

With reference to the alleged administration of arsenic in cocoa in Madeline Smith’s case, the following details will be illustrative.

100 grains of white arsenic were found to be a small teaspoonful, not heaped. This quantity was mixed with two teaspoonfuls of Epps’s cocoa. The colour was rendered lighter, but still looked natural. On making up with boiling water and milk, as directed, a cup of cocoa was obtained, in which neither appearance, taste, nor smell, betrayed anything unusual. On standing the milk rapidly curdled, and the arsenic deposited, but this would not be seen in an opaque cup. With arrowroot or gruel a similar result was obtained.[140]

It has been stated that arsenic trioxide volatilizes with the vapour of water. I have not found this to be the case to any appreciable extent, but it does volatilize slowly at 100° C., and still more at 120°. About ½ gramme of As₂ O₃ lost, after six hours on the water-bath, 3 per cent. of its weight; after six hours at 120° C. it lost six per cent. When chlorides are present, as in the body, it is still more liable to volatilization as arsenic trichloride. Hence matters containing it cannot be boiled down or dried without danger of loss, unless previously rendered alkaline.

R. Otto has stated that ordinary sulphuretted hydrogen may contain arsenic from the sulphate of iron used. He proposes to prepare the gas by the action of pure hydrochloric acid on pure calcium sulphide obtained by roasting gypsum with charcoal (Ber. Chem. Ges. xii. 250). I have tested water into which sulphuretted hydrogen has been repeatedly passed, and have found no arsenic: if really present in the gas, the As H₃ is not absorbed in the liquid.