Arsenic is by far the most important of metallic poisons, whether we consider the deadliness of its effects or the fatal frequency with which they are made manifest. Arsenic exists as an impurity in several metallic ores, notably in iron pyrites, which being commonly employed as a material for the manufacture of sulphuric acid, renders arsenic one of the most frequent impurities of commercial oil of vitriol. This should never be forgotten in testing any substance for the poison. To the common medicinal preparation of arsenic, consisting of arsenious acid, or arsenites, and the so-called chloride of arsenic, must be added the arseniates of potash and soda; the sulphides of arsenic—as, the red sulphide, or realgar, and the yellow sulphide, or orpiment; the arsenite of copper, or Scheele’s green, and others. They all produce similar symptoms, and poisoning by either of them requires nearly the same treatment.

According to Von Tschudi, some of the peasants in parts of Styria and Hungary eat arsenic, taking from two to five grains daily; the men doing so in order that they may gain strength, and be able to endure fatigue, the women that they may improve their complexions. These statements are so contrary to all that we know of the power of this poison, that they have been regarded as unworthy of credit. Evidence has, however, been brought forward by Dr. Craig Maclagan, of Edinburgh, which shows clearly that arsenic-eating is something more than a mere fiction. This gentleman gave, and saw a Styrian eat, a piece of arsenious acid, weighing over four grains, and afterwards determined the presence of arsenic in urine passed in his presence by the said peasant. Advantage was taken of these reports in the trial of Miss Madeline Smith (Edinburgh, July, 1857), when the court was asked to believe that arsenic found in the possession of the prisoner was used by her as a cosmetic.

Arsenite of Copper, in one form or another, either as Scheele’s green, emerald green, Brunswick green, &c., is unfortunately largely employed in the manufacture of green paper-hangings, artificial flowers, toys, and even some kinds of confectionery. Too many cases of ill-health caused by this practice have been recorded to permit any doubt as to its deleterious effects. These may be manifested by people living in rooms furnished with such paper-hangings. The chief symptoms are, sneezing, lachrymation, frontal headache, nausea, and loss of appetite, with colicky pains, thirst, &c. Among those employed in preparing the paper-hangings more serious symptoms manifest themselves. The irritation of the pigment gives rise to circular patches of ulceration on the alÆ of the nose, in the folds of the arm, in the groin and scrotum—in short, wherever dirt tends to lodge. These prove very untractable, except the employment be abandoned. In November, 1861, a young woman died in London from the poisonous effects of arsenite of copper used in dusting wax leaves. The workmen who employ the pigment in its dry state suffer, while those who use it in a moist condition are probably unaffected by it. A simple method for roughly detecting arsenite of copper in these fabrics was published in the Chemical News (vol. 1, p. 12). A small portion of the suspected material is to be put into a test tube with strong ammonia. If a blue tint be produced, a salt of copper is shown to be present. Withdraw the object, and drop a piece of nitrate of silver into the ammonia; if arsenic be there, the nitrate of silver will be covered with a yellow coating of arseniate of silver, which will disappear on stirring. On igniting arsenical paper and allowing it to smoulder, the odor of garlic may be detected in the fumes given off. Another mode in which the noxious effects of arsenic are produced is by the use of bright green tarlatans as ball dresses. One could hardly conceive a more deadly amusement than dancing in an arsenicated dress, sweeping against an arsenicated wall-paper. When both are lightly adherent the arsenic is scattered in showers about the room.

Arsenious Acid (White Oxide of Arsenic, White Arsenic, Arsenic).—This is the preparation of arsenic most frequently used as a poison; the facility with which it used to be procured, its cheapness (twopence an ounce), and the ease with which it may be administered, all tended to recommend it to the murderer or suicide. According to a parliamentary report, the number of fatal cases of poisoning in England in the years 1837, 1838, amounted to 543, of which no less than 186 were caused by arsenic, 185 arising from the use of the arsenious acid, and 1 from orpiment or yellow arsenic.

Since the Act of 1851 (14 Vict. cap. xiii.) the deaths from this agent have greatly decreased. This statute chiefly enacts that arsenic is not to be sold without the seller entering the transaction in a proper book, without a witness, nor without its being mixed with soot or indigo, unless such admixture would render it unfit for the purchaser’s business.

Arsenious acid is found in commerce in the form of a white powder or in small opaque cakes. It is very feebly acid, tasteless, or slightly sweet in small doses, though not very soluble, an ounce of cold water dissolving about one grain. The quantity so held in solution may, however, be increased by dissolving the arsenic in boiling water and allowing it to cool. The shortest period within which it was believed arsenic would cause death was two hours; but Dr. Taylor gives a case where death with tetanic symptoms followed the fatal dose in twenty minutes. The smallest quantity known to have proved fatal is two grains. Two grains and a half killed a girl nineteen years of age in thirty-six hours. Half a grain will produce alarming symptoms; and yet recovery has ensued after doses of half an ounce or an ounce.

Symptoms.—These commence within half an hour or an hour of swallowing the poison. There is faintness, nausea, incessant vomiting, and a burning pain in the epigastrium, increased on pressure, and gradually extending over the whole abdomen, followed by headache, diarrhoea, a sense of constriction and heat in the fauces and throat, great thirst, and catching, painful respiration. The heart’s action becomes depressed, the pulse is quick and feeble; there is great restlessness and anxiety; cold, clammy skin, and perhaps coma are present; and death usually occurs within twenty-four hours.

These symptoms are liable to great variety, the pain and vomiting being occasionally absent, and the patient being affected as if by a narcotic poison. In some instances there is troublesome tenesmus, with heat and excoriation about the anus. Convulsive movements in the extremities often occur, with cramp in the legs, especially if the diarrhoea is severe. Death sometimes takes place calmly from collapse, sometimes it follows on convulsions.

The vomited matters may be red or brown from admixture with blood or bile; or they may be blue or black, if the arsenic has been colored with indigo or soot. Although the vomiting, pain, &c., are generally continuous, yet sometimes all the symptoms remit, and the patient rallies for a time, only to sink more rapidly.

The symptoms of chronic poisoning by arsenic are loss of appetite, a silvery coating to the tongue, thirst, nausea, colicky pains, diarrhoea, frontal headache, langor, sleeplessness, cutaneous eruptions, soreness of the edges of the eyelids, emaciation, anÆmia, convulsions, and death. In some cases, when small doses have been administered for many days in succession, with the intent to destroy life, the symptoms have been masked by other substances. The most marked results of this practice have been sickness and vomiting, pain in the bowels, nervous irritability, and emaciation. The practitioner must be careful not to mistake these symptoms for those due to simple gastritis or enteritis.

Arsenic is not a poison that accumulates in the system, but is slowly eliminated from it especially by the kidneys, but partly also by the bile.

The local application of arsenic to the mucous membranes, to wounds, or to surfaces deprived of their cuticle, produces constitutional effects similar to those just described. The only difference is that the symptoms show themselves more slowly. Not a few lives have been sacrificed from the application by ignorant quacks of a mixture of arsenious acid, realgar, and oxide of iron to ulcerating cancers.

Cases of compound poisoning have been met with. When arsenic is taken mixed with opium, the symptoms produced by the former are masked.

Post-mortem Appearances.—Arsenic appears to exercise a specific influence over the alimentary canal, and more especially over the stomach; for in whatever manner it may have been introduced into the system, it is to this organ that we must look for its effects. These effects consist in the signs of acute inflammation commencing in this viscus, and often extending along the duodenum, small intestines, and colon. In acute cases the stomach is the viscus most affected; but in chronic cases the whole alimentary canal is found inflamed and ulcerated, particularly the duodenum and rectum. When death has occurred within five hours of taking the poison, the stomach has been found intensely inflamed in an adult; while the same result was witnessed in a child who died at the end of two hours. The stomach often contains a dark grumous fluid, occasionally tinged with blood. On removing the contents the mucous membrane is seen red and inflamed, the inflammation being most intense around certain spots. On examining these spots, particles of arsenic will probably be found adhering to the walls of the stomach and surrounded by a zone of inflammatory redness. Sometimes also blood is effused into the visceral walls, giving rise to an appearance resembling gangrene. Ulceration of any of the coats of the stomach is rare, and perforation is still more so.

In a few exceptional cases there has been no appearance of inflammation in the stomach or bowels.

Putrefaction of the body is said to be remarkably retarded after death from arsenic.

Treatment.—The first object must be to expel the poison from the stomach, for which purpose the stomach-pump may be advantageously employed, or emetics of sulphate of zinc, mustard, or ipecacuan administered, unless vomiting is already present. The sickness must be promoted by the free use of albuminous or mucilaginous diluents. Raw eggs beaten up in milk are particularly useful, as is likewise a mixture of albumen, milk, and limewater. Taylor advises equal parts of oil and limewater, for the oil invests the poison, and the lime renders it less soluble. A large dose of castor oil (?j to ?ij) may be given, to carry off any of the poison which may have passed into the intestines, as soon as sickness has subsided. Animal charcoal, calcined magnesia, &c., when taken in large quantities, may be of service by enveloping the arsenic, and preventing its contact with the mucous membrane of the stomach; but oil or milk will act more efficiently in this manner. The hydrated peroxide of iron[B] should be administered moist, and in large doses, after the stomach-pump has been used; or indeed, mixed with water, it may be first introduced and then expelled, thus washing out the stomach by means of the stomach-pump. This is the most efficient antidote known.

The subsequent treatment must be conducted on general principles, according to the severity of the symptoms; but the great depression of the nervous and vascular systems must not be overlooked in combating any inflammatory action. Henbane or opium, in many instances combined with stimulants, ice internally, and hot fomentations externally, will frequently be found of great service.

Tests.—In its solid state arsenious acid may be known by the following properties. Heated on platinum foil or on the point of a penknife, it produces a white smoke and is entirely volatilized. If some of the powder be heated in a small test tube, it will be sublimed, and small octahedral crystals, visible to the naked eye or by a lens, obtained. If arsenious acid be mixed with freshly-burnt powdered charcoal, and heated in a small test tube, a ring of shining metallic arsenic of a grey color will be found on the cool portion of the tube, and an odor of garlic is perceptible. If this deposit be driven about from place to place it will gradually become oxidized, and octahedral crystals of arsenious acid formed. Further, if the tube be divided and the part containing the arsenious acid be washed out with distilled water, the liquid tests may be applied to the solution. This is called the Reduction test. It is very delicate, detecting according to Christison, the 300th part of a grain.

In solution, this substance may be detected by what are called the liquid tests. A solution of arsenic in water is colorless, almost tasteless, and has a very slightly acid reaction. If a few drops be evaporated on a glass slide and examined by the microscope, numerous minute and mostly imperfect octahedral crystals, or an amorphous deposit, will be seen, presenting triangular surfaces by reflected light.

1. The ammonio-nitrate of silver (prepared by adding a few drops of liquor ammoniÆ to a solution of nitrate of silver, till the brown oxide of silver at first precipitated is nearly redissolved) throws down with arsenious acid a rich yellow deposit of arsenite of silver.

2. The ammonio-sulphate of copper (formed by adding liquor ammoniÆ to a solution of sulphate of copper till the bluish-white oxide of copper is almost redissolved) produces a pale green precipitate, arsenite of copper, or Scheele’s green. Care must be taken not to add too much of the test in the first instance, otherwise its blue may overpower the green of the precipitate.

3. Sulphuretted hydrogen water precipitates a yellow deposit of sulphide of arsenic. It is better, however, to use pure and well-washed sulphuretted hydrogen generated in the usual manner. Care must be taken that the liquid is not alkaline, or no precipitate will be produced, even though arsenic be present. For this reason yellow sulphide of ammonium will not precipitate arsenic until acidulated with pure hydrochloric or some such acid. The precipitate should be collected, carefully washed, and dried. It should then be mixed with black flux or dry ferrocyanide of potassium and reduced, as already described.

These tests are so delicate, especially the first, that they will detect the 8000th part of a grain of arsenic in solution; they should be employed successively. There are several other processes which require to be noticed, namely, Marsh’s process, the process known as Reinsch’s process, Fresenius’s process, and the Destillation process.

Marsh’s Test or Process.—This process is founded on the decomposition of arsenious acid by nascent hydrogen, and the formation of arsenuretted hydrogen gas, which possesses the following properties: It burns with a bluish-white flame, and white smoke (arsenious acid), possessing a slight garlic odor. If a piece of glass or porcelain be held in the flame a blackish metallic stain will be deposited upon it, consisting of metallic arsenic. This stain might be confounded with one produced by antimony under similar circumstances. But the antimonuretted hydrogen gas does not burn with the odor of the arsenuretted hydrogen; while the antimonial stain is sooty, and has not a metallic lustre. The arsenical stain is further readily dissolved by a solution of chloride of lime (bleaching powder), whilst the antimonial stain is not affected. To the stain may be added a few drops of strong nitric acid; it will dissolve the arsenic; if this be allowed to evaporate, and the acid be neutralized, a few drops of nitrate of silver solution will give a brick-red precipitate of arseniate of silver.

Marsh’s test is thus accomplished: a flask furnished with a cork through which pass a funnel and a long bent tube drawn to a point, is prepared so that the funnel reaches almost to its bottom. Several pieces of pure zinc are introduced, and then some sulphuric acid is poured through the funnel. In this way hydrogen gas is produced and escapes by the bent tube. When all the air has been expelled the gas should be ignited as it escapes, and a piece of cool porcelain held over the flame. If there be no deposit it is plain that neither the zinc nor the sulphuric acid, contains arsenic. A portion of the suspected fluid is next introduced into the flask by the funnel, and the issuing gas again tested. Should a stain giving the characters alluded to above be produced, the fluid contains arsenic in some form or other.

Reinsch’s Process.—The suspected liquid is boiled with from one-sixth to one-eighth of its bulk of pure hydrochloric acid, and a bright slip of copper introduced. If arsenic be present the copper will be coated with it in the form of an iron-grey deposit. Next after removing the copper, washing it with distilled water, and drying it between folds of blotting paper, cut it into slips, and introduce it into a reduction-tube and apply heat; arsenious acid will be sublimed and deposited on the sides of the tube, in the form of minute octahedral crystals. These may be dissolved in water and tested in the usual way. Before resorting to this test, the acid must be examined to make sure of its purity. This is easily effected by boiling the copper with a mixture of the hydrochloric acid and distilled water before adding the suspected liquid. In conducting the analysis in the case of Smethurst (Cent. Crim. Court, Aug. 1859) Taylor and Odling found that all the varieties of copper in common use for Reinsch’s process contained arsenic. A copper of ascertained purity must therefore be used.

Arsenic in Organic Matters.—The following process, which has been introduced by Dr. Taylor, is a very convenient one. The suspected matters are to be thoroughly dried in a water-bath or otherwise, taking care not to use too great a heat. They are then to be introduced into a flask fitted with a long bent tube; to the dried material is to be added a quantity of strong hydrochloric acid, proved free from arsenic, sufficient to drench it, and the whole allowed to digest for some hours. At the end of that time heat is to be applied to the flask by means of a sand-bath, and a receiver fitted to the bent tube. The receiver should contain a little water, and both it and the bent tube should be kept cool. As distillation goes on the arsenic passes over in the form of chloride of arsenic, and is collected in the receiver beyond. A second portion of hydrochloric acid may be used to remove any last traces of arsenic in the organic material. The arsenic may be recovered from the chloride by boiling with pure polished copper, as in Reinsch’s process.

The process of Fresenius and Von Babo given at page 31 is especially adapted for the recovery of arsenic from organic admixture.

Several cases of poisoning by arsenuretted hydrogen are on record, some proving fatal.