Action of hydro-cyanic Acid as a Poison.
The experiments which have been instituted with a view to ascertain the exact effects of this substance upon animal life, very clearly prove that the acid of Gay-Lussac is one of the most active poisons in nature; and that the various vegetable bodies, into whose composition it enters, exert an energy, corresponding with the quantity of this constituent, and the degree of concentration, in which it exists. The experiments of M. Orfila were made with Prussic acid, prepared according to the process of Scheele, and consequently containing a great proportion of water, as we have already explained; and yet the effects which followed its administration were extremely energetic. From the Annales de Chimie, for October 1814, we learn that a professor of chemistry, having inadvertently left on his table a phial filled with a solution of Prussic acid in alcohol, a female servant, who had been seduced by its agreeable smell, drank a small glass-full of it, and fell dead at the end of a few minutes, as if struck by apoplexy.
The following case is quoted by Dr. Granville, from Hufeland. D. L. a robust and healthy man, aged 36 years, while about to be seized as a thief by the police officers, snatched a small sealed phial from his pocket, broke off the neck of it, and swallowed the greatest part of its contents. A strong smell of bitter almonds soon spread around, which almost stupefied all present. The culprit staggered a few steps; then, without a groan, fell on his knees, and sunk lifeless down to the ground. Medical assistance being called in, not the slightest trace of pulse or breathing could be found. A few minutes afterwards, a single and violent expiration occurred, which was again repeated in about two minutes. The extremities were perfectly cold, the breast and abdomen still warm, the eyes half open and shining, clear, lively, full, almost projecting, and as brilliant as those of the most ardent youth under violent emotion. The face was neither distorted nor convulsed, but bore the image of quiet sleep. The corpse exaled a strong smell of bitter almonds, and the remaining liquid, being analysed, was found to be a concentrated solution of Prussic acid in alcohol. Cases also stand recorded where, from imprudent exposure to the vapours of the Prussic acid, persons have exhibited all the appearances of being poisoned. Some writers assert that Scheele himself, who died suddenly, while engaged in some inquiries into the nature and formation of this acid, was affected by its deleterious qualities. Orfila relates that Scharinger, Professor at Vienna, prepared some pure concentrated Prussic acid, and having diffused a certain quantity of it upon his naked arm, he died a short time afterwards. The professor, however, did not die in consequence of this accident; it appears, upon inquiry, that he was seized with apoplexy while sitting in a coffee house in the evening.
The distilled water of the cherry laurel[[438]] has been proved, by numerous awful examples, to be a most energetic poison; and from the fatal effects to which the officinal preparation of it gave rise, it was early expunged from the Pharmacopœia of the London College. In the Philosophical Transactions for the year 1731, we shall find the history of its effects upon a woman of the name of Boyce, who, with a view to disprove an allegation, that one Mary Whaley had died in consequence of drinking a small quantity of laurel water, swallowed three spoonsful, and, afterwards, two more of the same liquid; after which she died in a very short time, without making the least complaint, and without any convulsion.
Foderé informs us that during the period he was pursuing his studies at Turin in 1784, the chambermaid and man servant of a noble family of that town, for the purpose of regaling themselves, stole from their master a bottle of distilled laurel water; fearful of being surprised, they hastily swallowed several mouthsful of it; but they soon paid the price of their dishonesty, having almost instantly expired in convulsions. Works on Toxicology also abound with the relation of experiments, made by numerous physiologists on different animals, with this deleterious liquid. Amongst the experimentalists we may enumerate the names of Madden, Mortimer, Browne, Langrish, Nicholls, Stenzelius, Heberden, Watson, Vater, Rattrai, the Abbé Rozier, Duhamel, Fontana, and Orfila. In this country we have had several fatal cases of poisoning by laurel water. In the year 1782, Dr. Price, of Guildford, having professed to have converted mercury into gold, offered to repeat his experiments before a competent tribunal, but the unfortunate philosopher put a period to his existence before the day appointed for his exhibition, by a draught of laurel water; a mode of death which had been, no doubt, suggested by the celebrated trial of Donellan, for the murder of Sir Theodosius Boughton, that had taken place in the preceding year, and left a strong impression upon the public mind; and whose details, it has been justly observed, are not more important from the elucidation of the effects of this poison, than from the strange display of professional testimony to which it gave origin, (see Appendix, page 243.) There are those who still profess to believe that the prisoner was unjustly convicted upon that occasion; Dr. Male states, without the least reserve, that it was neither proved that the deceased was poisoned, nor that any poison had existed.[[439]] We feel no difficulty in declaring that we hold a directly opposite opinion; and we consider that many of the weaker points of professional evidence delivered on the trial, have received powerful support and elucidation from the experiments and observations of later physicians.
Nor are the leaves of this plant wholly free from danger; it is true that they have, for many years, been in general use among cooks, to communicate an almond or kernel-like flavour to custards, puddings, creams, blanc-mange, and other delicacies of the table; but the custom has not always been harmless; a fact with which it behoves the forensic physician to be acquainted. In some parts of the continent milk is boiled with one or two leaves of the cherry-laurel in it, and Ingenhouz states that he saw people much affected by it. In the Literary Chronicle (no. xxii, p. 348, 1819) we find the following illustrative case: “Several children at a boarding-school, in the vicinity of Richmond, having partaken of some custard flavoured with the leaves of the cherry-laurel, four of them were taken severely ill in consequence. Two of them, a girl of six, and a boy of five years of age, fell into a profound sleep, out of which they could not be roused for ten hours, the other two complained of severe pains in the epigastric region. By proper medical treatment, they all recovered, after an illness of three days.”
The essential oil of bitter almonds is equally poisonous; and the water distilled from them is highly dangerous if incautiously taken. Duvignau and Parent instituted some experiments upon themselves to ascertain this fact; they commenced by taking six drops of the water distilled three times, in an appropriate vehicle, without producing any other than a transient impression. On taking eighteen drops, however, vertigo was experienced, and a disposition to sleep, accompanied with a tingling of the ears and dimness of sight. When the dose was increased to twenty-two drops, alarming symptoms followed, such as convulsions, and vomiting; which, although the experimenters succeeded in allaying by antispasmodics, cured them completely of any ulterior wish to ascertain how far this substance might be deleterious. A drachm of the distilled water of bitter almonds has killed a moderate sized dog. The essential oil is proportionally more active; Mr. Brodie[[440]] found that one drop, when applied to the tongue of a cat, killed it in five minutes; no sooner did the poison come in contact with the organ than the animal was seized with convulsions. When two drops of the same oil were injected with half an ounce of water into the rectum of a cat, it was not seized for two minutes, but it died, as in the former experiment, after the expiration of five minutes. While engaged in this inquiry, Mr. Brodie dipped the blunt end of a probe into the essential oil, and applied it to his tongue, with the intention of tasting it, and not having the least suspicion that so small a quantity could produce any of its specific effects on the nervous system; but scarcely had he applied it, when he experienced a very remarkable and unpleasant sensation, which he referred chiefly to the epigastric region, but the exact nature of which he could not describe, because he knew nothing similar to it. At the same time there was a sense of weakness in his limbs, as if he had not the command of his muscles; and he thought that he should have fallen. The fascinating liqueur noyau, créme de noyau, is indebted for its flavour to the essential oil of the bitter almond, or peach; and is undoubtedly deleterious if taken in excess. In the Journal des Debats, for 1814, we find that the late Duke Charles de Lorraine had nearly lost his life from swallowing some drops of eau de noyau too strongly impregnated with the essential oil of peach kernels.
The bitter almond itself, in consequence of the manner in which its deleterious principle is modified by the natural state of combination in which it exists with sweet oil and albumen, does not produce an effect corresponding with the proportion of essential oil which it yields. The experiments of Orfila, however, prove that the almond, in doses of a drachm, is destructive to cats; and there can be no doubt but that it would be equally deleterious to the human species; but the quantity required for the production of such an effect must ever prevent the bitter almond from becoming either the accidental or criminal instrument of death.
Physiological action of Prussic acid.
The numerous experiments, which have been made with this poison, have clearly established that its action is upon the nervous system, whose energies it would seem to extinguish without any ostensible injury to respiration and circulation; for in all those animals which were killed by it, in the experiments of Orfila, Brodie, and others, the heart was found acting regularly, and circulating dark coloured blood, and in some cases this phenomenon was visible for many minutes after the animal was in other respects apparently dead. Orfila considers that he has fully demonstrated that these effects depend on the absorption of the poison, and its transmission to the brain through the medium of the circulation. We have accordingly placed Prussic acid in the second division of our classification. The essential oil of bitter almonds would, according to the experiments of Mr. Brodie, appear to act through the medium of the nerves, and it has accordingly been referred to our first division. This is undoubtedly an anomaly, which it is not easy to reconcile; the experiments, however, which led Mr. Brodie to the conclusion appear to us to warrant such a deduction; the instantaneousness with which the poisonous effects were produced, and the fact of its acting more speedily when applied to the tongue, than when injected into the intestines, although the latter presents a better absorbing surface, seem to oppose the idea of the oil requiring to be absorbed, before it can display its energies. M. Vogel, of Munich, has lately discovered some facts respecting the composition of this oil, which may perhaps hereafter lead to the true explanation of this apparent anomaly; this distinguished chemist succeeded in separating the Prussic acid from the volatile oil with which it is combined, by agitating the whole in a concentrated solution of potass, and distilling to dryness; the oil volatilized together with the water, while the residuum in the retort was found to contain cyanide of potassium. The oil, thus separated from the Prussic acid, is without odour, and heavier than water; its taste is extremely acrid and burning; in order to discover whether it was still poisonous, M. Vogel put a drop of it on the tongue of a sparrow, when it died in a few seconds, after a very violent convulsion; he also poisoned a dog, two months old, with four drops of it; whence he concludes that the volatile oil, divested of its hydro-cyanic acid is still a poison, although less energetic than that which has not undergone such a change. Do there exist then two independent principles of activity in the bitter almond? If such a fact were established it would not be solitary, for we shall hereafter shew that the energies of tobacco are dependant upon an analogous arrangement; and that our ignorance of the fact, at first, occasioned apparent anomalies, as embarrassing as those which at present involve the physiological history of the oil of almonds.