[81] Dr Blondlot, in a paper communicated to the Paris Academy of Sciences, has come to the conclusion that the slightest quantity of greasy matter in contact with arsenious anhydride reduces its solubility to about 1-20th of what it was before. This explains at once why, in certain judicial investigations, arsenic has been sought for in vain in the liquid contents of the stomach, when the food consisted partly of fatty substances, such as broth, milk, &c. It likewise explains how arsenious anhydride, taken in powder, may sometimes remain a long time in the stomach before it produces any deleterious effect; since, in such cases, its action is hindered by the presence of fatty matter. Jugglers often swallow arsenic with impunity, because, according to Dr Blondlot, they previously take the precaution to drink milk and eat fat bacon. Hence, in cases of poisoning by arsenic, oils and fatty substances may be administered as real antidotes, capable of suspending the action of the poison for a considerable time, until more radical means of effecting a cure can be applied. The people engaged in some of the arsenic-works regard salad oil as almost a certain antidote to this poison.
Uses, &c. Arsenious anhydride and its compounds are extensively employed in the arts and medicine. It is used by the dyer, it furnishes the artist with several of his most beautiful pigments, and the glass-maker and enameller with a flux or material to whiten and decolour their wares. In agriculture, it is used (in solution) as an anti-smut for seed-wheat; and as an anti-vermin lotion or dipping for sheep and cattle. In small (therapeutical) doses it is a valuable remedy in intermittent fevers, chronic skin diseases (especially lepra and psoriasis), and in several nervous affections (as neuralgia, epilepsy, chorea, tetanus, &c.). It is the active ingredient of the tasteless ague-drop; of Fowler’s and Pearson’s solutions; and in the Tanjore pills, long celebrated in India for the cure of the bite of the cobra di capello and other venomous serpents, as well as of hydrophobia. It has been given in syphilis, chronic rheumatism, typhus, and several other diseases, with more or less advantage. Cautiously administered in phthisis, it frequently restores the appetite and strength and greatly retards, and in some cases arrests, the progress of the disease. It has been recently used to relieve toothache arising from caries. Externally, it is employed in the form of powder, lotion, and ointment, for the cure of cancer. Plunkett’s ointment, Pâte arsénicale, Davidson’s Remedy for Cancer, and several other like preparations, owe their activity to arsenious anhydride. Water in which white arsenic has been steeped has become a favorite cosmetic wash with many ladies, since its assumed property of softening the skin was announced in a certain popular periodical. It is also the prime ingredient in the papier moure, a popular fly paper. Its use, whether internal or external, is, however, attended with considerable danger in unskilful hands, and should, therefore, never be adopted but under proper advice.—Dose, 1⁄20 to 1⁄8 gr., made into pills with crum of bread and lump sugar; or in solution, 3 to 5 or 6 drops, twice or thrice daily, gradually and cautiously increased to 12, or even 15 drops. As a rule, arsenical preparations should be taken soon after a meal, and by no means on an empty stomach. (Dr A. T. Thomson.) The dose should be suspended, or greatly reduced, as soon as the conjunctiva is affected (Hunt); or if dryness of the mouth or throat, or irritation of the stomach or bowels, ensues. Mr Maculloch found the pills more efficacious than the solution; they act differently, and cannot be substituted for one another.
Arsenic is a favorite tonic and alterative with farriers, who often administer it very carelessly to horses, to the serious injury of these animals. It is also a favorite with grooms, who have imbibed the notion that small doses of it contribute to improve the condition of the skin. The best-informed veterinarians, however, either wholly avoid it, or use it with very great caution.[82]—Dose (for a HORSE), 2 to 5 or 6 gr., twice or thrice daily; in farcy or glanders, 10 to 12 gr. In solution it is often employed as a wash or dipping to destroy vermin in cattle and sheep; but its use is not free from danger, particularly to the shepherds or dippers.
[82] “As a therapeutic agent for horses, arsenious acid can be well dispensed with. It is, however, employed by some as a tonic, in doses of from 10 to 20 gr. daily; and by others as a vermifuge. When injudiciously administered death has been the result. By those of the old school it is extolled as a caustic, and a very powerful one doubtlessly it is; but there is this disadvantage attending its use—we cannot control its action, and, oftentimes, a most extensive and painful wound is caused by it. Occasionally it is resorted to for the eradication of warts; although a better plan is to extirpate them at once with the knife. When, however, this is inadmissible, 1 part of arsenious acid, in very fine powder, may be mixed with 4 parts of lard, and a (small) portion of the compound applied, with friction, over and around the excrescence every other day, for three or four times. This will excite such a powerful sloughing action, that in about 10 days the warts will be thrown off.” (Prof. Morton.)
Gen. commentary. The necessary length of the preceding article, owing to the great importance of the subject in its relations to toxicology and medical jurisprudence, has left us little space for further remark here. In addition to what has been said on arsenical testing, it may be useful to caution the reader of the absolute necessity of only employing tests and reagents which are themselves absolutely pure; and in which the operator has, by personal examination, failed to detect the slightest trace of arsenic. Commercial sulphuric, nitric, and hydrochloric acids, potash, soda, nitre, iron, and zinc, frequently contain
arsenic; from which, however, they may be freed by chemical processes; or they may be purchased in the pure state from respectable dealers in chemicals. But no assurance of the vender should be regarded as a proof of their purity. In all judicial investigations the absence of arsenic in the several tests and reagents, and the apparatus employed, must be demonstrated and sworn to. We may further add, that the results afforded by no single test can be depended on. In matters of such vast importance, the most ample confirmatory evidence must be sought.
Marsh’s, Reinsch’s, Lassaigne’s, the sulphur, and the Reduction Tests, and their modifications, are those now generally preferred by toxicological chemists; each of which, with its confirmatory tests, are amply sufficient for the indisputable identification of arsenic.
Modern toxicologists have abandoned most of the old processes for the detection of arsenic, and have adopted one of two, which have been found more expeditious as well as more certain. These are the tests of Marsh and Reinsch, preferably the latter.
Herapath’s Method is to obtain deposits by Reinsch’s Test on 4 or 5 pieces of No. 13 copper wire; each piece being about 21⁄2 inches long, and previously flattened and planished with a polished hammer for about one half its length. The deposit, with some of the adhering copper, scraped from one of these coated pieces, is sealed up hermetically in a tube for future production. The scrapings from three pieces of wire are separately submitted to the sublimation test in tubes bent in the form of an obtuse V capillary at one end, and about 3⁄10ths of an inch in diameter at the other; the capillary leg being about three times as long as the larger one. The scrapings are placed in the bent part of the tube; and the flame of a small spirit lamp is so applied as to slowly drive the sublimate into the narrower portion of the tube, which is held rather higher than the other. If the deposit so obtained be mercury, it condenses in white shining globules;—if lead or bismuth, it does not rise but melts into a yellowish glass, which adheres to the copper; if tellurium, it falls as a white amorphous powder; if antimony, it does not rise at that low temperature; but if it be arsenic, it sublimes as arsenious anhydride, which condenses as minute octahedral crystals, looking, with the microscope, like very transparent grains of sand. One of these tubes containing the sublimed arsenious anhydride is then sealed up, like the first one, for future production. The capillary part of another tube containing the sublimate is then cut off, and carefully boiled in a few drops (10 to 15) of distilled water; and, when cold, 3 or 4 drops of the resulting solution is poured on a plate of white porcelain, and to this, by means of a glass rod, one drop of solution of ammoniacal sulphate of copper is added. The mixture is then carefully conducted on to a piece of white filtering-paper set on the surface of a smooth, clean, and dry chalk-stone, by which the moisture is absorbed, and the smallest portion of Scheele’s green produced by the test rendered more conspicuous. The ammonio-nitrate of silver test is then applied, in a similar manner, to 3 or 4 drops of the remaining solution; after which the pieces of paper with the spots are dried, and sealed up in separate tubes, as before, observing to exclude the light from that containing the yellow precipitate of arsenite of silver. A stream of sulphuretted hydrogen is then passed through the remaining tube containing the arsenical sublimate, by which the latter is converted into the yellow tersulphide—this too is sealed up. Here are now five tests—the metal, the acid, arsenite of copper, arsenite of silver, and yellow tersulphide of arsenic.
It is now well known that certain soils contain arsenic, either as arsenite of lime or sulphide of arsenic; and which, under favorable circumstances, may permeate or be absorbed by a body, after interment. In judicial investigations following disinterment it is, therefore, necessary to examine portions of the cemetery-earth taken from the grave, as well as from parts more or less distant from it. For this purpose the earth should be thoroughly dried in a water-bath, drenched with pure and concentrated hydrochloric acid, and allowed to stand for twenty-four hours. The mixture is then distilled, and the distillate tested for arsenic by Reinsch’s or Marsh’s test. Should the product of one distillation yield no evidence of arsenic, it should be returned to the retort, if necessary, a second or even a third time, and the distillation repeated.