The last method for removing opium from the stomach is a desperate one, which can only be recommended when emetics by the mouth have utterly failed, and when a stomach-pump or Mr. Bryce’s substitute, cannot be procured. It is the injection of an emetic into the veins. Tartar-emetic answers best for this purpose, and its effect is almost certain. A grain is the dose. While injecting it, care must be taken by the operator not to introduce air into the vein.
The next object in conducting the treatment of poisoning with opium is to keep the patient constantly roused. This alone is sufficient when the dose is not large, and the poison has been discharged by vomiting; and in every case it forms, next to the evacuation of the stomach, the most important of the treatment.
The best method of keeping the patient roused is to drag him up and down between two men, who must be cautioned against yielding to his importunate entreaties and occasional struggles to get free and rest himself. For the sopor returns so rapidly, that I have known a patient answer two or three short questions quite correctly on being allowed to stand still, and suddenly drop the head in a state of insensibility while standing. The duration of the exercise should vary according to circumstances from three, to six, or twelve hours. When he is allowed at length to take out his sleep, the attendants must ascertain that it is safe to do so by rousing him from time to time; and if this should become difficult, he must be turned out of bed again and exercised as before.
It appears from some cases published not long ago by Mr. Wray[1797] and Dr. Copland,[1798] and more lately also by Dr. Bright,[1799] that the most insensible may be roused to a state of almost complete consciousness for a short time, by dashing cold water over the head and breast. This treatment can never supersede the use of emetics: and as its effect is but temporary, it ought not to supersede the plan of forced exercise. But it appears to be an excellent way to insure the operation of emetics. If the emetic is about to fail in its effect, cold water dashed over the head restores the patient for a few moments to sensibility, during the continuance of which the emetic operates. Dashing cold water over the head may perhaps be dangerous in the advanced stage, when the body is cold and the breathing imperceptible; but the most desperate remedies may be then tried, as the patient is generally in almost a hopeless state. In one of the cases mentioned by Dr. Bright from the experience of Mr. Walne, complete recovery was accomplished, mainly by cold affusion of the head, where there appeared reason to believe that more than an ounce and a half of laudanum had disappeared from the stomach before evacuating remedies were used.—This treatment seems to have been first proposed in 1767 by a German physician, Dr. Gräter.[1800] A suggestion, which is probably an improvement, has been recently made by Dr. Boisragon of Cheltenham, to alternate the use of cold with that of warm water, applied to children in the shape of warm bath, and to adults in the form of warm-sponging and the foot-bath. The alternating impression of heat and cold may act better as a stimulant than either agent singly; and the occasional employment of heat prevents the risk of collapse from too continuous exposure to cold. Dr. Boisragon saved in this way two cases in very unpromising circumstances.[1801]
In some cases internal stimulants have been given with advantage, such as assafœtida, ammonia, camphor, musk, &c. It is always useful to stimulate the nostrils from time to time, by tickling them or holding ammonia under the nose; but the application should be neither frequent nor long continued, as the ammonia may cause deleterious effects when too freely inhaled. Pulling the hair and injecting water into the ears are also powerful modes of rousing the patient.
Venesection has been recommended and successfully used by some physicians. If the stomach be emptied, and the patient kept roused, as may almost always be done when means are resorted to in time, venesection will be unnecessary. Sometimes, however, when the pulse is full and strong, it may be prudent to withdraw blood; and it certainly appears that in most cases where this remedy has been employed the sensibility began to return almost immediately after. This is very well shown in a case of poisoning with opium related by Mr. Ross[1802] in the Edinburgh Medical Journal, in another described in the same journal by Mr. Richardson,[1803] and also in two cases of poisoning with acetate of morphia mentioned in a former page. Sometimes, on the contrary, it has seemed injurious, probably because it was not had recourse to till the patient was moribund. It is a sound general rule that blood-letting ought not to be resorted to until the poison is thoroughly removed from the stomach; for it favours absorption. And yet facts are not wanting to show that this rule, now generally admitted since the researches of Magendie on absorption, is not infallible. Dr. Young of the United States has given the particulars of a case where imperturbable coma was formed, together with puffing stertorous respiration, in consequence of an ounce of laudanum having been swallowed,—and where recovery took place, without the poison having been removed at all, simply under the employment of three blood-lettings to the amount of twenty-eight ounces altogether, of cold to the head, and of sinapisms to the legs.[1804]
Galvanism has been sometimes resorted to, but seldom with decided advantage. I saw it tried, with dubious utility, a few years ago in an urgent case which was treated in the Edinburgh Infirmary. Six ounces of laudanum had been swallowed, but most of it was removed in three-quarters of an hour by the stomach-pump. A stage of deep sopor followed, after which sensibility was restored, and maintained for four hours by forced exercise. A state of pure and extreme coma then ensued, during which galvanism was for some time of great service, in rousing the patient. Gradually, however, it ceased to have any effect of the kind. Recovery took place eventually under the use of external and internal stimuli. Mr. Erichsen of the University-College Hospital, London, has related a case, in which electro-magnetism was of undoubted service. The usual symptoms had been occasioned by an ounce of laudanum. The poison had been withdrawn by the stomach-pump, when unavailing attempts were made to restore sensibility by means of various stimulants. At length several electro-magnetic shocks were passed from the forehead to the upper part of the spine, with the effect of speedily eliciting signs of consciousness; in twenty minutes the patient could answer questions and walk a little; and eventually complete recovery took place.[1805]
In desperate circumstances artificial respiration may be used with propriety. After the breathing has been almost or entirely suspended the heart continues to beat for some time; and so long as its contractions continue, there is some hope that life may be preserved. But it is essential for the continuance of the heart’s action, that the breathing be speedily restored to a state of much greater perfection than that which attends the close of poisoning with opium. It is not improbable that the only ultimate cause of death from opium is suspension of the respiration, and that if it could be maintained artificially so as to resemble exactly natural breathing, the poison in the blood would be at length decomposed and consciousness gradually restored. The following is an interesting example by Mr. Whately, in which artificial respiration proved successful. A middle-aged man swallowed half an ounce of crude opium and soon became lethargic. He was roused from this state by appropriate remedies, and his surgeon left him. But the poison not having been sufficiently discharged, he fell again into a state of stupor; and when the surgeon returned, he found the face pale, cold and deadly, the lips black, the eyelids motionless, so as to remain in any position in which they were placed, the pulse very small and irregular, and the respiration quite extinct. The chest was immediately inflated by artificial means, and when this had been persevered in for seven minutes, expiration became accompanied with a croak, which gradually increased in strength till natural breathing was established. Emetics were then given, and the patient eventually recovered.[1806]—Dr. Ware of Boston (U. S.) has more lately described another case, where artificial respiration was employed with marked advantage, and would probably have saved the patient’s life in very unfavourable circumstances, but for the disease on account of which the opium was given.[1807]—Another has been lately described by Mr. C. J. Smith of Madras. The patient was not seen for four hours, and received no benefit from the ordinary remedies during the next hour and a half. Artificial respiration was then resorted to and maintained for nearly five hours with an hour of interval; and this measure certainly seems to have brought the case to a favourable termination under most unpromising circumstances.[1808]—Dr. Watson of Glasgow has mentioned to me the particulars of an instructive base in the person of an infant three weeks old, in whom, after the breathing had stopped and the heart had nearly ceased to beat, the occasional inflation of the chest with the breath at intervals of two or three minutes restored for a time the action both of the heart and lungs, and eventually accomplished recovery. On physiological principles it appears probable, that this simple mode of procedure may prove more frequently successful than might at first be thought.
It would be a fruitless task to examine into the merits of the numerous antidotes which have from time to time been proposed for poisoning with opium. Professor Orfila has examined many of them with great care, such as vinegar, tartaric acid, lemonade, infusion of coffee, decoction of galls, solution of chlorine, camphor, diluents; and he has found them all useless before the poison is expelled from the stomach, with the single exception of decoction of galls. As he remarked that this fluid throws down the active principles of an infusion of opium, and subsequently found that such a mixture acts more feebly on the animal system than the opiate infusion itself, he thinks the decoction of galls may with propriety be used as an imperfect antidote, till the poison can be evacuated from the stomach.[1809] His experiments, however, do not assign to it very material activity as a remedy; and certainly the whole efforts of the physician ought in the first instance to be directed to the removal of the opium, and to keeping the patient roused. When the opium has been completely removed, the vegetable acids and infusion of coffee have been found useful in reviving the patient, and subsequently in subduing sickness, vomiting, and headache; but till the poison is completely removed the administration of acids is worse than useless, provided the opium was given in the solid state, because its solution in the juices of the stomach is accelerated. It has been maintained that iodine, chlorine, and bromine are all antidotes for poisoning with the vegetable alkaloids.[1810] Some notice will be taken of this statement in the chapter on Nux Vomica. It has also been lately alleged in the United States that opium has no effect when given with acetate of lead; and an hospital case is reported as having occurred at New York, where the poison was swallowed in this way to the extent of thirty grains, without any injurious effect.[1811] There must have been some mistake here, however. When given with acetate of lead in medicinal doses, opium exerts its usual sedative and anodyne action; and indeed there is no chemical or physiological reason why it should not do so.
Of Poisoning with Hyoscyamus.—Of the narcotic poisons none bears so close a resemblance to opium in its properties as the hyoscyamus or henbane. Several species are poisonous; but the only one that has been examined with care is the H. niger, from which the extract of the apothecary is prepared.
The hyoscyamus has been analyzed by various chemists, and found to contain a peculiar alkaloid, in which the properties of the plant are concentrated. It is named hyoscyamia. This substance in its pure state, as first obtained by MM. Geiger and Hesse, is a solid body, in fine silky crystals, without odour, of a strong acrid taste like tobacco, partially volatilizable with boiling water, entirely volatilizable alone at a somewhat higher heat, very soluble in alcohol and ether, but sparingly so in water.[1812]
Farther, hyoscyamus, like many other narcotic vegetables, stramonium, digitalis, opium, tobacco, and hemlock, has been found by Mr. Morries Stirling to yield by destructive distillation an empyreumatic oil of great activity. Its poisonous properties, however, are not essential to the oil, but reside in a volatile principle which may be detached by weak acetic acid. The relation of this principle to hyoscyamia has not been ascertained; but it is an active poison, small doses producing in rabbits, convulsions, coma, and speedy death.[1813]
Runge proposes as evidence of poisoning with hyoscyamus, in common, however, with stramonium and belladonna, to concentrate a solution of the contents of the stomach, and apply it to a cat’s eye to dilate the pupil. Dilatation, he says, was even produced by an extract obtained from the urine of a rabbit which had been fed some time on hyoscyamus.[1814]
According to the experiments of Professor Orfila, the juice or extract procured from the leaves, stems, and especially the root, produces in animals a state of sopor much purer than that caused by opium. It is most active when injected into the jugular vein, less so when applied to the cellular tissue, and still less when introduced into the stomach. Except occasional paralysis of the heart, indicated by florid blood in its left cavities, no morbid appearance is to be found in the dead body. Six drachms of the pharmaceutic extract of the leaves killed a dog in two hours and a quarter when swallowed; and three drachms killed another in four hours through a wound in the back. Its action appears to be exerted through the medium of the blood-vessels, and is purely narcotic.[1815]
It is probable that the activity of this plant is much affected by season; and the energy of its preparations varies greatly with the manner of obtaining them. The information, however, which is at present possessed on these two points is vague, because the influence of the two circumstances has seldom been viewed carefully apart.
The leaves, from which the pharmaceutic preparations of hyoscyamus are obtained, are commonly held to be most active during the inflorescence of the plant in the second summer of its existence. On general principles this appears probable; but there are no satisfactory experiments on the subject, even the late researches of Mr. Houlton having left much still to be determined.[1816]
Orfila has made some important remarks as to the effect of season and vegetation on the energy of the root as a poison. The root he maintains is the most active part of the plant; but in the spring it is nearly inert. Thus the juice of three pounds of the root collected near the end of April, when the plant has hardly begun to shoot, killed a dog in somewhat less than two days; while a decoction of an ounce and a half collected on the last day of June, when the plant was in full vegetation, proved fatal in two hours and a half.
The extract of the leaves, procured from different shops, was found by Orfila to vary greatly in point of strength, some samples being absolutely inert.[1817] The causes of these differences have been ascertained experimentally by Brandes to be, that the herb loses its active principle in part by decomposition in the process of simple desiccation, and also when long kept; and that the greater part is also similarly decomposed in preparing an extract, unless the process be finished quickly, and at a low heat.
The seeds of hyoscyamus are poisonous, as well as the leaves and root. Indeed the whole plant is so. The seeds contain much more hyoscyamia than the leaves.
The effects of hyoscyamus on man differ somewhat from those on animals, and vary greatly with the dose.
In medicinal doses it commonly induces pleasant sleep. This indeed has been denied by M. Fouquier, who infers from his experiments that it never causes sleep, but always headache, delirium, nausea, vomiting, and feverishness.[1818] I have certainly seen it sometimes have these effects; but much more generally it has acted as a pleasant hypnotic and anodyne.
Its effect in large doses have been well described by M. Choquet as they occurred in two soldiers who ate by mistake the young shoots dressed with olive oil. They presently became giddy and stupid, lost their speech, and had a dull, haggard look. The pupils were excessively dilated, and the eyes so insensible that the eyelids did not wink when the cornea was touched. The pulse was small and intermitting, the breathing difficult, the jaw locked, and the mouth distorted by risus sardonicus. Sensibility was extinct, the limbs were cold and palsied, the arms convulsed, and there was that singular union of delirium and coma which is usually termed typhomania. One of the men soon vomited freely under the influence of emetics, and in a short time got quite well. The other vomited little. As the palsy and somnolency abated, the delirium became extravagant, and the patient quite unmanageable till the evening of the subsequent day, when the operation of brisk purgatives restored him to his senses. In two days both were fit for duty.[1819]
In a treatise on vegetable poisons, Mr. Wilmer has related the history of six persons in a family, who were poisoned by eating at dinner the roots of the hyoscyamus by mistake instead of parsneps. Several were delirious and danced about the room like maniacs, one appeared as if he had got drunk, and a woman became profoundly and irrecoverably comatose. Emetics could not be introduced into the stomach, stimulant clysters had no effect, external stimuli of every kind failed to rouse her, and she expired next morning at six.[1820] The roots in this instance were gathered in the winter time,—a fact, which does not quite coincide with the conclusions of Orfila, that the plant must be in full vegetation before the energy of the root is considerable.
From these and other cases, the abstracts of which are to be seen in Orfila’s Toxicology, or in Wibmer’s Treatise on the Operation of Medicines and Poisons, it follows that hyoscyamus in a poisonous dose causes loss of speech, dilatation of the pupil, coma, and delirium, commonly of the unmanageable, sometimes of the furious kind. In general a stage of delirium precedes coma; and sometimes as the coma passes off, delirium returns for a time. It has been known to act powerfully in the form of clyster.[1821] It has also been known to act with considerable energy even through the sound skin, as appears from a case which occurred to Wibmer. He was called to a lady affected with great stupor, dilated pupils, flushed face, loss of speech, full hard pulse, and swelling of the abdomen; and he found that these symptoms were owing to several ounces of henbane leaves having been applied to the belly in a poultice, on account of strangury and tympanitis. She was still capable of being roused by speaking loudly close to her ear; and under proper treatment she recovered.[1822]
Henbane seldom causes any distinct symptoms of irritant poisoning. In several, however, of the cases related by the older modern authors some pain in the belly, a little vomiting, and more rarely diarrhœa, appear to have occurred.[1823] Plenck quotes, from a Swedish authority, an instance of its having produced burning in the stomach, intense thirst, watching, delirium, depraved vision, and next day a crowded eruption of dark spots and vesicles, which disappeared on the supervention of a profuse diarrhœa.[1824] The same author alludes to cases where it proved fatal; but this event is rare in the present day, obviously because the precursory stage of delirium gives an opportunity of removing the poison, before the stage of coma is formed. A fatal case, which occurred to Mr. Wibmer, has been mentioned above; and another has been related in Pyl’s Magazin. Two boys a few minutes after eating the seeds were attacked with convulsions and heat in the throat; and one of them, who could not be made to vomit, died in the course of the ensuing night.[1825]
The accidents it has occasioned have commonly arisen from the individuals confounding the root with that of the wild chicory or with the parsnep, the latter of which it somewhat resembles.
Of the other species of the hyoscyamus, the H. albus has been known to cause symptoms precisely the same with those above described. Professor Foderé has given a good example of its effects on man, as they occurred in the crew of a French corvette in the Archipelago. The plant was boiled and distributed among the whole ship’s company, as several of the sailors said they knew it to be eatable and salubrious. But in no long time they were all seized with giddiness, vomiting, convulsions, colic, purging, and delirium of the active kind. They were all soon relieved by emetics and purgatives.[1826]
Dr. Archibald Hamilton has described a case of the same nature, which was caused by the seeds of this plant. A young medical student, who took about twenty-five grains of the seeds, was seized in half an hour with lassitude and somnolency, and successively with dryness of the throat, impeding deglutition, convulsive movements of the arms, incoherency, total insensibility of the skin, and loss of recollection. These symptoms continued about twelve hours, and then slowly receded.[1827]
Three other species, the H. aureus, physaloides and scopolia are represented by Orfila to be equally deleterious.
The alkaloid hyoscyamus possesses in an intense degree the active properties of the plant. It has not been hitherto examined in this respect with much care. But extremely minute quantities produce excessive enlargement of the pupil, when put within the eyelids in the form of neutral salt.
Treatment.—The treatment of poisoning with hyoscyamus consists in removing the poison, diminishing cerebral congestion, and restoring sensibility. It is therefore substantially the same as in poisoning with opium, except that general or local evacuation of blood is more frequently required, in consequence of the greater tendency of hyoscyamus to induce determination of blood towards the head and congestion there. It has been lately alleged by an Italian author that a large dose of lemon-juice is an immediate antidote for the effects of too large a medicinal dose, even when the poison was administered in the form of injection.[1828] This does not seem probable.
Allied in its effects, but greatly inferior in power to opium and hyoscyamus, is the Lactuca virosa, together with the Lettuce-opium, or inspissated juice of L. sativa, and L. virosa.
Orfila found that three drachms of the extract of L. virosa introduced into the stomach of a dog killed it in two days, without causing any remarkable symptom; that two drachms applied to a wound in the back induced giddiness, slight sopor, and death in three days; and that thirty-six grains injected in a state of solution into the jugular vein caused dulness, weakness, slight convulsions, and death in eighteen minutes.[1829] This poison, therefore, like other narcotics, acts through absorption. But it is far from being energetic. The extract is very uncertain in strength,—as may indeed be inferred from the variable nature of the processes by which it is prepared.
Lactucarium, the inspissated juice, especially that obtained from L. virosa, is obviously a more active preparation than the extract. Doses of no great magnitude kill small animals. But there is a want of good observations on its effects and energy as a poison.
Different species of solanum, a genus of the same natural order with the hyoscyamus, have been considered by Orfila to possess the same properties, though in a much feebler degree. The S. dulcamara or bittersweet has been erroneously believed by some to possess distinct narcotic properties.[1830] M. Dunal found that a dog might take 180 of the berries or four ounces of the extract without any inconvenience, and quotes an experiment on the human subject where thirty-two drachms of extract were taken in two doses also without injury.[1831] If it has any power at all, therefore, it must possess too little to be entitled to the name of a poison. Chevallier says he knew an instance of a druggist’s apprentice being attacked with deep somnolency for ten hours after carrying a large bundle of it on his head;[1832] but some other cause may be justly suspected to have here been in operation. The S. nigrum or common nightshade has been made the subject of experiment by Orfila, who found its extract to possess nearly the power and energy of lettuce-opium.[1833] The following seems a genuine case of poisoning with the berries of this species. Three children near Nantes in France were seized with severe headache, giddiness, colic, nausea, and vomiting. One of them then had excessive dilatation of the pupils, sweating and urgent thirst; loss of voice, stertorous breathing, and tetanic spasms ensued; and in twelve hours he died. Another had swelling of the face, alternate contraction and dilatation of the pupils, repeated vomiting, and eventually coma; but he recovered. The third was similarly, but more slightly affected, and also recovered. The children who recovered pointed out the berries they had eaten; which were found to be those of S. nigrum.[1834] The S. fuscatum is rather more active, fifteen berries having caused hurried breathing and vomiting.[1835] The S. mammosum is also probably an active species, the capsule of the berries having been known to excite vomiting, giddiness, and confusion of mind.[1836] In the S. nigrum and dulcamara, M. Desfosses discovered in 1821 a peculiar alkaloid, which induces somnolency in animals, but is not a very active poison.[1837]
It has been supposed by some that the tubers of Solanum tuberosum, the common potato, may acquire in certain circumstances poisonous qualities of no mean energy. Dr. Kabler of Prague has described the cases of four individuals in a family who were seized with alarming narcotic symptoms after eating potatoes which had begun to germinate and shrivel. The father of the family, who had eaten least of them all, appeared as if tipsy, and soon became insensible. The mother and two children became comatose and convulsed. All had vomited before becoming insensible. They recovered under the use of ether, frictions, and coffee; and in two hours were out of danger.[1838]
An alkaloid has been indicated by several chemists in various species of solanum. The most recent account, that of Otto, represents it to be a pearly, white, pulverulent substance, alkaline in reaction, and capable of uniting with acids. One grain of sulphate of solania killed a rabbit in six hours, and three grains a stronger rabbit in nine hours,—the symptoms being those of narcotic poisoning.[1839]
Violent effects have often been assigned to the genus Solanum, in consequence of its similarity to a powerful poison, the Atropa belladonna; which indeed is described by the older authors under the name of Solanum furiosum. It will be noticed among the Narcotico-acrid Poisons.
The poisons, whose energy depends on the presence of the prussic or hydrocyanic acid, are of great interest to the physiologist as well as the medical jurist. Some of them are natural productions, derived from the leaves, bark, fruit-kernels, and roots of certain plants; others are formed artificially by complex chemical processes. The species to be here noticed are the hydrocyanic acid itself, and the essential oils and distilled waters of the bitter almond, cherry-laurel, peach-blossom, cluster-cherry, mountain-ash, and bitter cassava. These poisons have for some time attracted great attention on account of their extraordinary power. And indeed in rapidity of action, or the minuteness of the quantity in which they operate, no poison surpasses and very few equal them. They are exceedingly interesting to the medical jurist, because, as they are now generally known, their effects often become the subject of medico-legal investigation: they have been repeatedly taken by accident; they have often been resorted to for committing suicide; and they have likewise been employed as the instruments of murder. A remarkable instance occurred in England towards the close of last century, where murder was committed with the cherry-laurel water; and two cases have been tried in England where death arose from hydrocyanic acid, and the prisoners were charged with administering it, but were found not guilty. These cases will be noticed presently.
This singular substance was discovered some time ago by Scheele; but Gay-Lussac was the first who obtained it in a state of purity. It is familiarly known to chemists under two forms,—as a pure acid, and diluted with water.
The pure acid is liquid, limpid, and colourless. It has an acrid, pungent taste, and a very peculiar odour, which, when diffused through the air, has a very distant resemblance to that of bitter almonds, but is accompanied with a peculiar impression of acridity on the nostrils and back of the throat. It is an error, however, to suppose, as is very generally done, that the odour is the same with that of the almond. It boils at 80°; freezes at 5°; and is very inflammable. I have kept it unchanged for a fortnight in ice-cold water; but at ordinary temperatures it decomposes spontaneously, and becomes brown, sometimes in an hour, and commonly within twelve hours. On this account it is extremely improbable that a case will ever happen, in which the medical jurist will have to examine it in its concentrated form.
When united with water it forms the acid discovered by Scheele, and now kept in the druggist’s shop. In this state it has the same appearance, taste, and smell as the pure acid; but it is less volatile, does not burn, and may be preserved long without change, if excluded from the light. In consequence of its volatility, however, it becomes weak, unless kept with great care; many samples of it also undergo decomposition, and deposit brown flakes, if not excluded from the light; and hence the acid of the shops is very variable in point of strength. The acid prepared by decomposing the solution of the ferro-cyanate of potass by sulphuric acid may be kept for years, even exposed to diffuse light, without being decomposed at all. A French physician made some experiments not long ago on the uncertainty of the strength of the medicinal acid; and he found that he could swallow a whole ounce of one sample, and a drachm of a stronger sample, without sustaining any injury; but on trying some which had been recently prepared by Vauquelin, he was immediately taken ill, as will be related presently, and narrowly escaped with his life.[1840]—The acid of commerce differs much in strength, according to the process by which it has been prepared, and independently of decomposition by keeping. The medicinal acid long used in this country is intended to be an imitation of that of Vauquelin, which contains 3·3 per cent.;[1841] but the London College of Physicians, in adopting it in their last Pharmacopœia, improperly altered the strength to 2 per cent. That of Giese, which keeps well, is of the same strength as the first; that of Schrader contains only one per cent.; that of Göbel 2·5 per cent.; that of Ittner 10 per cent.;[1842] that of Robiquet 50 per cent.[1843] Of the alcoholic solutions the best known are that of Schrader, which contains about 1·5 per cent. of pure acid,—that of the Bavarian Pharmacopœia, which contains 4 per cent.,—that of Duflos, 9 per cent.,—that of Pfaff, 10 per cent.,—and that of Keller, 25 per cent.[1842] These statements are necessary for understanding the cases of poisoning published in foreign works.
The tests for hydrocyanic acid has been examined by M. Lassaigne of Paris, by Dr. Turner of London, and by Professor Orfila. They are its odour, the salts of copper, the salts of iron, and nitrate of silver.
The peculiar odour of the acid is a very characteristic and delicate test of its presence. According to Orfila, the smell is perceptible when no chemical reagent is delicate enough to detect it.[1844] But I doubt the accuracy of this statement, and may farther observe, that I have known some persons nearly insensible of any smell, even in a specimen which was tolerably strong. Hence, when the odour is resorted to as a test, it ought to be tried by several persons.
Sulphate of copper forms with hydrocyanic acid, when rendered alkaline with a little potass, a greenish precipitate, which becomes nearly white, on the addition of a little hydrochloric acid. The purpose of the hydrochloric acid is to redissolve some oxide of copper thrown down by the potass. The precipitate is then the cyanide of copper. This test, according to Lassaigne, will act on the poison when dissolved in 20,000 parts of water. But as the precipitate is not coloured, the test is an insignificant one compared with the next.
If the acid be rendered alkaline by potass, the salts of the mixed peroxide and protoxide of iron produce a grayish-green precipitate, which, on the addition of a little sulphuric acid, becomes of a deep prussian blue colour. Common green vitriol answers very well for this purpose. The salts of the peroxide of iron will also often answer, because, unless carefully prepared, they are never altogether free of protoxide. But the salts of the pure peroxide of iron have no such effect. They cause with the potass a brownish precipitate, which is redissolved on the addition of sulphuric acid, leaving the solution limpid. Mr. Ilott of Bromley has pointed out to me, that the iron test does not act on a weak solution of hydrocyanic acid, if there be an excess of ammonia present, either such from the first, or disengaged by potash from muriate of ammonia; that the blue precipitate is produced by driving off the ammonia with heat; but not by neutralizing it with an acid.
The nitrate of silver is a delicate and characteristic reagent for hydrocyanic acid. A white precipitate, the cyanide of silver, is produced in a very diluted solution; and this precipitate is distinguished from the other white salts of silver, by being insoluble in nitric acid at ordinary temperatures, but soluble in that acid at its boiling temperature. In this action it is necessary to observe that something more is accomplished than simple solution; the cyanide is decomposed, nitrate of silver is formed, and hydrocyanic acid is disengaged by the ebullition. A more characteristic property is, that the precipitate when dried and heated emits cyanogen gas; which is easily known by the beautiful rose-red colour of its flame.[1845]
Sometimes it is necessary to determine the strength of diluted hydrocyanic acid; because, on account of its tendency to decomposition, doubts may be entertained whether a mixture which contains it is strong enough to be dangerously poisonous. According to Orfila, the best method of ascertaining the strength either of a pure solution or of a mixture in syrup, is to throw down the acid with the nitrate of silver and dry the precipitate; a hundred parts of which correspond to 20·33 of pure hydrocyanic acid.
Process for Mixed Fluids.—Some important observations have been made by MM. Leuret and Lassaigne on the effect of mixing animal matters with hydrocyanic acid. The most material of their results are, that if the body of an animal poisoned with the acid is left unburied for three days, the poison can no longer be detected; and that if it is buried within twenty-four hours the poison may be found after a longer interval, but never after eight days. The reason is either that the acid volatilizes, or that it is decomposed. The possibility thus indicated of detecting the poison in the body some days after death has been since confirmed by actual examination in a medico-legal case. In a case of poisoning with hydrocyanic acid, followed by dismemberment of the body for the purpose of concealment, distinct proof of the presence of the poison seven days after death was obtained by the second of the succeeding processes, although the trunk of the body had never been buried, but had been for some time lying in a drain.[1846]
For detecting the poison in mixed fluids Orfila has lately advised the following process. The fluid may be treated with animal charcoal without heat. The colour being thus generally destroyed, the test will sometimes act as usual. Or, without this preparation, a slip of bibulous paper moistened with pure potass, may be immersed in the suspected fluid for a few minutes, and then touched with a solution of sulphate of iron: upon which the usual blue colour will be produced on the paper. If neither of these methods should answer, the fluid is to be distilled.[1847]
Distillation of the fluid is on the whole the best mode of procedure. It was proposed some time before by Lassaigne and Leuret for detecting the poison in the stomach after death. The steps of their process, which appears to me the best yet proposed, are as follows. The contents after filtration are to be neutralized with sulphuric acid if they are alkaline, in order to fix the ammonia which may have been disengaged by putrefaction; the product is then to be distilled from a vapour-bath till an eighth part has passed over into the receiver; and the distilled fluid is to be tested with the sulphate of iron in the usual way.[1848] Orfila maintains that from hydrocyanized syrup only two-thirds of the acid can be distilled over; and cautions the analyst against estimating quantity by such means.[1849] M. Ossian Henry has proposed to condense the acid in distillation by a much more complex process, which consists in obtaining it in the first instance in the form of cyanide of silver.[1850] But with a good refrigeratory there is no difficulty in condensing every particle of acid with no other aid than cold water.
By this process Lassaigne could detect the poison in a cat or dog killed by twelve drops and examined twenty-four or forty-eight hours after death.[1851] But Dr. Schubarth has objected to it,—and the same objection will apply to every process in which heat is used,—that hydrocyanic acid may be formed during distillation by the decomposition of animal matter.[1852] His objection, however, appears only to rest on conjecture or presumption at farthest; and I doubt whether, supposing the distillation to go on slowly in the vapour-bath, the heat is sufficient to bring about the requisite decomposition. The force of the objection must be decided by future researches.
It is worthy of remark that hydrocyanic acid is apt to be formed in the course of the changes produced by various agents in organic matters. These are probably more numerous than the toxicologist is at present exactly aware of. An instance of its formation in the course of the decay of unsound cheese has been ascertained lately by Dr. Witling;[1853] and another example will be mentioned under the head of spurred rye.
Cyanide of Potassium.—The only compound of hydrocyanic acid which requires notice is the cyanide of potassium. This is, when pure, a white salt, bitter, not decomposable by a red heat unless in contact with air, very soluble in water, and sparingly so in rectified spirit. Its watery solution restores the blue of reddened litmus, and does not precipitate lime-water: the mixed sulphates of the two oxides of iron form with it Prussian blue: nitrate of silver causes a white precipitate insoluble in cold nitric acid, but disappearing when the acid is boiled: sulphate of copper causes an apple-green precipitate, which becomes white on the addition of hydrochloric acid: chloride of platinum or perchloric acid will indicate the potash. In a complex organic mixture it is difficult to detect the potash; but hydrocyanic acid may be obtained from it by distilling the suspected fluid with tartaric acid.[1854]