Of the different preparations of arsenic, it may be said in general terms, that those are most active which are most soluble. In conformity with what appears to be a general law in toxicology, the metal itself is inert. It is difficult to put this fairly to the test, because it is not easy to pulverize the metal without a sufficient quantity being oxidated to cause poisonous effects. Bayen and Deyeux, however, found that a drachm carefully prepared might be given in fragments to dogs without injuring them; and they once gave a cat half an ounce without any other consequence than temporary loss of flesh.[[578]] Its alloys are also inert. The same experimentalists found it inactive when combined with tin; and Renault likewise found it inactive when united with sulphur and iron in the ore mispickel, or arsenical pyrites.[[579]]
It is probable that all the other preparations of arsenic are more or less deleterious.
A difference of opinion prevails as to the power of the sulphurets. Various statements have been published on the subject. But it may be sufficient to observe, that in consequence of the poisonous properties of the sulphurets having been imputed to the oxide, with which they are often adulterated,—Professor Orfila made some experiments with native orpiment and realgar, and with the sulphuret procured by sulphuretted-hydrogen gas (which are all pure sulphurets); and he found that in doses varying from 40 to 70 grains they all caused death in two, three, or six days, whether they were applied to a wound, or introduced into the stomach.[[580]] It may appear at first view singular that the sulphurets, being insoluble, should be poisonous; but the apparent anomaly vanishes on considering the experiments of M. Decourdemanche formerly noticed; which prove that in animal fluids the sulphurets are rapidly changed into the oxide (see p. [225]). The sulphurets, however, are much less active than the preparations in which the metal exists already oxidated. Yet in sufficient doses they will prove rapidly fatal. In the Acta Germanica there is the case of a woman who was killed in a few hours by realgar, mixed by her step-daughter in red cabbage soup.[[581]] The common artificial orpiment procured by sublimation is very active, in consequence of the oxide mixed with it. Renault found three grains killed a dog in nine hours.[[582]]
Among the less active preparations of arsenic may also be enumerated such of the arsenites and arseniates as are not soluble in water. They have not indeed been actually tried. But there can be little doubt that they will prove poisonous; because, though insoluble in water, they are probably somewhat soluble in the animal juices. We may infer from their sparing solubility, even in these menstrua, that they will be less active than the preparations now to be mentioned, which are more soluble.
These are the alkaline arsenites and arseniates, arsenic acid, arsenious acid, the black oxide or fly-powder, and arseniuretted-hydrogen. With regard to arsenic acid, and the alkaline arseniates and arsenites, it is probable, from their effects in medicinal doses, that they are as active as the white oxide, if not more so. But they have not been particularly examined, as they are not objects of great interest to the medical jurist.
The fly-powder or black oxide is very active. Renault found that four grains killed a middle-sized dog in ten hours.[[583]] It has been likewise known to prove quickly fatal to man. In a French journal there is a case related which ended fatally in sixteen hours;[[584]] and in the Acta Germanica is an account of four persons, who died in consequence of eating a dish of stewed pears poisoned with it, and of whom three died within eighteen hours.[[585]] The dose is not mentioned; but it is probable from the collateral circumstances that it was not considerable.
Arseniuretted-hydrogen is probably the most active of all arsenical compounds. The celebrated German chemist Gehlen, having accidentally inhaled a small portion of it, died in nine days with the usual symptoms of arsenical poisoning. In Dr. O’Reilly’s case, which proved fatal in seven days, it was computed that the equivalent of twelve grains of oxide had been inhaled. And Dr. Schlinder’s patient had inhaled a quantity of gas corresponding with only an eighth of a grain of sesquioxide; yet he appears to have made a narrow escape.[[586]]
It is of some consequence to settle with precision the power of the white oxide. Witnesses are often asked on trials how small a quantity will occasion death? It is obvious that this question admits only of a vague answer: It can be answered at all only in reference to concomitant circumstances, and even then but presumptively. Nevertheless, it is right to be aware what facts are known on the subject.
It has been stated by various systematic authors that the white oxide will prove fatal to man in the dose of two grains. Hahnemann says in more special terms, that in circumstances favourable to its action four grains may cause death within twenty-four hours, and one or two grains in a few days.[[587]] But neither he nor any of the other authors alluded to have referred to actual cases. Foderé knew half a grain cause colic pains in the stomach and dysenteric flux, which continued obstinately for eight days;[[588]] and I have related an instance where six persons, after taking each a grain in wine during dinner, were seriously and violently affected for twelve hours.[[589]] Mr. Alfred Taylor mentions three similar cases occasioned by arsenic accidentally taken in port wine after dinner,—one, an infant of sixteen months who got about a third of a grain, another, a lady who took a grain and a half, and the third, a gentleman, who had two grains and a half,—in all of whom violent vomiting, and prostration, without pain, occurred for three or four hours; and the gentleman of the party did not recover for several days.[[590]] M. Lachèse mentions his having met with a number of cases of poisoning from small doses taken in bread or soup; whence he concludes, that an eighth of a grain taken in food may cause vomiting;—that a quarter of a grain or twice as much taken once only causes vomiting, colic, and prostration,—that the same quantity repeated next day renews these symptoms in such force as to render the individual unfit for work till three or four days afterwards,—and that four such doses, taken at intervals during two days, that is between one and a half and two grains in all, excite acute gastro-enteritis and may prove fatal, since two individuals who had taken this much died, one in seven weeks, the other three weeks later.[[591]] The smallest fatal dose I have found recorded elsewhere is four grains and a half; and death ensued in six hours only.[[592]] But the subject was a child, four years old, and the poison was taken in solution. Alberti mentions the case of a man who died from taking six grains; but I am unacquainted with the particulars, not having seen the original account.[[593]] Two children, whose cases are alluded to in the Proceedings of the Academy of Medicine of Paris, died, the one in two days, the other a day later, after taking rather less than sixteen grains. The former was four years and a half old, the latter seven years.[[594]] Valentini alludes to a case where thirty grains of the oxide in powder killed an adult in six days.[[595]] The effects of medicinal doses, which seldom exceed a quarter of a grain without causing irritation of the stomach, and the fatal effects of somewhat larger doses on animals, Renault having found that a single grain in solution killed a large dog in four hours,[[596]] must convince every one that the general statement of Hahnemann cannot be very wide of the truth. Mr. Taylor thinks his own cases mentioned above throw doubt over this inference. But it must be remembered, that his patients had dined just before taking the poison.
It is not improbable that the activity of oxide of arsenic is impaired by admixture with other insoluble powders. M. Bertrand, conceiving from some experiments on animals that he had found an antidote for arsenic in charcoal powder, took no less than five grains of the oxide mixed with that substance, and he did not suffer any injury, although his stomach was empty at the time, and he did not vomit.[[597]] But Orfila afterwards showed, that other insoluble powders, such as clay, have the same effect; that no such powder can be of any use if not introduced into the stomach till after the arsenic is swallowed; and that they appear to act solely by enveloping the arsenical powder and preventing it from touching the membrane of the alimentary canal.[[598]] Although M. Bertrand’s discovery will not supply the physician with an antidote, the medical jurist will not lose sight of the interesting fact, that, by certain mechanical admixtures, arsenic in moderate doses may be entirely deprived of its poisonous quality. A singular case of recovery from no less a dose than sixty grains, which happened in the case of an American physician, probably comes under the same head with the experiments of Bertrand,—a large quantity of powder of cinchona-bark having been swallowed along with the arsenic. In this case, however, the symptoms were severe for three days.[[599]]