CHAPTER XXIX.

OF POISONING WITH HYDROCYANIC ACID. 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. _Of the Hydrocyanic Acid._ SECTION I.—_Of its Chemical History and Tests._ 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] SECTION II.—_Of the Action of Hydrocyanic Acid and the Symptoms it excites in Man._ The effects of hydrocyanic acid on the animal system have been examined by several physiologists. The best experiments with the concentrated acid are those of M. Magendie; who says that, if a single drop be put into the throat of a dog, the animal makes two or three deep hurried respirations, and instantly drops down dead; that it causes death almost as instantaneously when dropped under the eyelid; and that when it is injected into the jugular vein, the animal drops down dead at the very instant, as if struck with a cannon ball or with lightning.[1855] On repeating these experiments in order to determine less figuratively the shortest period which elapses before the poison begins to operate, as well as the shortest time in which it proves fatal,—two points it will presently be found important to know,—I remarked that a single drop, weighing scarcely a third of a grain, dropped into the mouth of a rabbit, killed it in eighty-three seconds, and began to act in sixty-three seconds,—that three drops weighing four-fifths of a grain, in like manner killed a strong cat in thirty seconds, and began to act in ten,—that another was affected by the same dose in five and died in forty seconds,—that four drops weighing a grain and a fifth did not affect a rabbit for twenty seconds, but killed it in ten seconds more,—and that twenty-five grains, corresponding with an ounce and a half of medicinal acid, began to act on a rabbit as soon as it was poured into its mouth, and killed it outright in ten seconds at farthest. Three drops injected into the eye acted on a cat in twenty seconds, and killed it in twenty more; and the same quantity dropped on a fresh wound in the loins acted in forty-five and proved fatal in 105 seconds. Dr. A. T. Thomson says he has seen the concentrated acid kill a strong dog in two seconds.[1856] Mr. Blake on the other hand alleges that all the accounts which represent the action of the poison to begin in less than ten seconds are exaggerated, because he could never find it to act more quickly, even when thirty minims of concentrated acid were injected at once into the femoral vein.[1857] But it is impossible that any negative results can outweigh positive observations, especially when made, as mine were, expressly with the view of ascertaining the shortest interval. In the slower cases enumerated above there were regular fits of violent tetanus; but in the very rapid cases the animals perished just as the fit was ushered in with retraction of the head. In rabbits opisthotonos, in cats emprosthotonos, was the chief tetanic symptom.—The practical application of these experiments will appear presently. Of all the forms in which the pure acid can be administered, that of vapour appears the most instantaneous in operation. M. Robert found, that when a bird, a rabbit, a cat, and two dogs were made to breathe air saturated with its vapour, the first died in one second, the second also in a single second, the cat in two, one dog in five, and the other dog in ten seconds.[1858] The effects of the diluted acid are the same when the dose is large, but somewhat different when inferior doses are given. These effects have been observed by many physiologists; but the most accurate and extensive experiments are those of Emmert published in 1805,[1859] those of Coullon in 1819,[1860] and those of Krimer in 1827.[1861] They found that when an animal is poisoned with a dose not quite sufficient to cause death, it is seized in one or two minutes with giddiness, weakness and salivation, then with tetanic convulsions, and at last with gradually increasing insensibility; that after lying in this state for some time, the insensibility goes off rapidly and is succeeded by a few attacks of convulsions and transient giddiness; and that the whole duration of such cases of poisoning sometimes does not exceed half an hour, but may extend to a whole day or more.—When the dose is somewhat larger the animal perishes either in tetanic convulsions or comatose; and death for the most part takes place between the second and fifteenth minute. I have seen the diluted acid, however, prove fatal with a rapidity scarcely surpassed by the pure poison. Thus in an experiment with Vauquelin’s acid, made on a strong cat at the same time with the second and third of the experiments with the pure acid detailed above, I found that thirty-two grains, which contain one of real acid, began to act in fifteen seconds, and proved fatal in twenty-five more. According to Schubarth’s experiments death may be sometimes delayed for thirty-two minutes;[1862] but if the animal survives that interval, it recovers. He farther states, that during the course of the symptoms the breath exhales an odour of hydrocyanic acid.[1863] Coullon once saw a dog die after nineteen hours of suffering; but cases of this duration are exceedingly rare.[1864] When the dose is very large Mr. Macaulay, as will afterwards be mentioned (p. 590), has found death take place in a few seconds, exactly as when the pure acid is given. The body presents few morbid appearances of note. The brain is generally natural. Yet occasionally its vessels are turgid; and Schubarth once found even an extravasation of blood between its external membranes in the horse.[1865] The heart and great vessels are distended with black blood, which is commonly fluid, but occasionally coagulated as usual. The lungs, according to Schubarth, are sometimes pale, but much more generally injected and gorged with blood.[1866] The pure acid, according to Magendie, exhausts the irritability of the heart and voluntary muscles so completely, that they are insensible even to the stimulus of galvanism.[1867] The diluted acid has not always this effect. In the experiments of Coullon the heart and intestines contracted, and the voluntary muscles continued contractile, after death as usual.[1868] So too Mr. Blake remarked both by inspection of the body after death, and by means of the hæmadynamometer during life, that, when the poison is introduced directly into a vein, so as to prove fatal in forty-five seconds, the contractions of the heart, though irregular, are not materially impaired in energy.[1869] On the other hand Schubarth states that the heart is never contractile, although the intestines and voluntary muscles retain their contractility.[1870] The reason of these discrepant statements is that, as I have had occasion to observe, a considerable difference really prevails in experiments conducted under circumstances apparently the same. In eight experiments on cats and rabbits with the pure acid the heart contracted spontaneously, as well as under stimuli, for some time after death, except in the instance of the rabbit killed with twenty-five grains, and one of the cats killed by three drops applied to the tongue. In the last two the pulsations of the heart ceased with the short fit of tetanus which preceded death; and in the rabbit, whose chest was laid open instantly after death, the heart was gorged and its irritability utterly extinct. The later researches of Dr. Lonsdale likewise show great varieties in the condition of the heart; and he has been led to conclude that the diluted acid does not perceptibly influence the heart, while the pure acid enfeebles it, if introduced into the stomach, but arrests it, if injected into the windpipe.[1871] The experiments of Emmert, Coullon, and Krimer show that the diluted acid acts most energetically through the serous membranes, and next upon the stomach; that it also acts with energy on the cellular tissue; that it has no effect when applied to the trunks or cut extremities of nerves, or to a fissure made in the brain or spinal marrow; that its action is prevented when the vessels of any part are tied before the part is touched with the poison; that its action is not prevented by previously dividing the nerves; and that it may sometimes be discovered in the blood after death by chemical analysis,[1872] and frequently by the smell when analysis cannot succeed in separating it.[1873] These results favour the supposition that hydrocyanic acid acts through the medium of the blood-vessels. But the extreme rapidity of its operation in large doses is usually considered incompatible with an action through the blood, or any other channel except direct conveyance along the nerves. The tremendous rapidity of action indicated by the experiments of Magendie, or of Mr. Macaulay (p. 543), of M. Robert, as well as in some of those performed by myself,—certainly appears rather inconsistent with the notion, that the acid must enter the blood-vessels before producing its effects. This acid acts on the brain and also on the spine independently of its action on the brain. Its action on both is clearly indicated by the combination of coma with tetanus. The independent action on the spine is well shown by the following experiment of Wedemeyer. In a dog the spinal cord was divided at the top of the loins, so that no movement took place when the hind-legs were pricked: hydrocyanic acid being then introduced into a wound in the left hind-leg, symptoms of poisoning commenced in one minute, and the hind-legs were affected with convulsions as well as the fore-legs.[1874] Hydrocyanic acid affects all animals indiscriminately. From the highest to the lowest in the scale of creation all are killed by it; and all perish nearly in the same manner. Such is the result of a very extensive series of experiments by Coullon. It is scarcely necessary to observe that hydrocyanic acid acts energetically as a poison, through whatever channel it is introduced into the body. Whether it be swallowed, or injected into the rectum, or dropped into the eye, or applied to a fresh wound, or inhaled in the form of vapour, its action is exerted with tremendous energy. Perhaps it may even act through the sound skin. It has not, hitherto, indeed, been found to affect animals in this way, evidently because their skin is too thick and impermeable. But M. Robiquet informed me that once, while he was making some experiments on the tension of its vapour, his fingers, after being some time exposed to it, became affected with numbness, which lasted several days; I have repeatedly remarked the same effect when handling tubes which contained the concentrated acid; and Emmert found that the essential oil of bitter almond, applied to the uninjured skin of the back of a rabbit, produced the usual symptoms and death: and that the peculiar odour of the poison was quite distinct after death in the deep-seated muscles of the back.[1875] This substance is poisonous in all its chemical combinations. Coullon remarked that two drops of the hydrocyanate of ammonia killed a sparrow in two minutes.[1876] Robiquet and Magendie found that a hundredth part of a grain of the cyanide of potassium killed a linnet in thirty seconds, and five grains a large pointer in fifteen minutes;[1877] Orfila has related an instance of death in the human subject within an hour after the administration of six grains of cyanide of potassium in an injection;[1878] and in a recent experimental investigation the same author found that this salt produces all the effects of hydrocyanic acid.[1879] Schubarth killed a dog in twenty minutes with twenty drops of the diluted acid neutralized by ammonia,[1880] and another in three hours with twenty-five drops neutralized by potass. These facts are a sufficient answer to a statement made by Mr. Murray of London, to the effect, that a considerable dose of the acid may be given without injury to a rabbit,[1881] if previously rendered alkaline by ammonia. But, nevertheless, as will be seen under the head of the treatment, ammonia, as Mr. Murray stated, is a good antidote when administered after the poison as a stimulant. The _ferro-cyanates_, or prussiates, do not possess deleterious properties. These salts were at one time considered compounds of hydrocyanic acid with a double oxidized base, oxide of iron being one. Thus the prussiate of potass was considered a compound of hydrocyanic acid with potass and oxide of iron. But since the investigations of Mr. Porrett, it has been admitted that there is only one base, potash; and that it is in union with a hydracid, called ferro-cyanic acid, the radicle of which is a ternary body composed of carbon, azote, and iron. The physiological effects of this substance, which have been examined by many experimentalists, are favourable to Porrett’s opinion; for although some have found it poisonous, all agree in assigning it very feeble properties, and some have not been able to discover in it any deleterious quality at all. Coullon observes that Gazan killed a dog with two drachms, and Callies another with three drachms of the salt met with in commerce.[1882] Schubarth found that half an ounce had not any material effect on dogs, even when vomiting did not occur for half an hour;[1883] and Callies, who found the salt of commerce somewhat poisonous, also remarked, that when it was carefully prepared, several ounces might be given without harm.[1884] D’Arcet once swallowed half a pound of a solution without any injury.[1885] Similar results were obtained previously with smaller doses by Wollaston, Marcet,[1886] and Emmert,[1887] as well as afterwards by Dr. Macneven,[1888] and Schubarth,[1889] who found that a drachm or even two drachms might be taken with impunity by man and the lower animals. The _sulpho-cyanic acid_, another substance analogous in chemical nature to the ferro-cyanic, was once supposed like it to be a poison of great activity, but this is doubtful. Professor Mayer of Bonn ascertained that a drachm and a half of a moderately strong solution of the acid sometimes killed a rabbit in ninety seconds when injected into the windpipe, and that the same quantity of a solution of sulpho-cyanate of potassa might occasion death in the course of four hours; but that some rabbits took half an ounce of the former and three drachms of the latter without material harm, both when administered through the windpipe, when injected into the rectum, and when introduced into the stomach by a gullet-tube. In the fatal cases death took place under symptoms of oppressed breathing, rarely attended with convulsions; and extensive traces of irritation were found in the alimentary canal.[1890] Dr. Westrumb of Hameln, however, seems to have found it more active in the form of sulpho-cyanate of potassa. Two scruples in an ounce of water produced in a dog spasmodic breathing, convulsions, efforts to vomit, and death in seven minutes; and forty grains killed another in less than two hours. In the latter animal he detected the poison by the sulphate of iron in the blood, lungs, liver, spleen and kidneys.[1891] Some experiments by Soemering would even make it out to be a poison of very great energy; for half a drachm of concentrated sulpho-cyanic acid given to a dog occasioned immediate death; and the same quantity of sulpho-cyanate of potassa killed another in one minute.[1892] _Cyanic and cyanous acids_ are not poisonous, according to the experiments of Hünefield;[1893] but _cyanogen_ is a powerful poison, as will be mentioned under the head of the Narcotic Gases. The symptoms of hydrocyanic acid observed in man are very similar to those witnessed in animals. Coullon has given a good account of the effects of small doses as ascertained by experiment on himself. When he took from 20 to 86 drops of a diluted acid, he was attacked for a few minutes with nausea, salivation, hurried pulse, weight and pain in the head, succeeded by a feeling of anxiety, which lasted about six hours.[1894] Such symptoms are apt to be induced by too large medicinal doses. Another remarkable symptom which has been sometimes observed during its medicinal use is salivation with ulceration of the mouth. Dr. Macleod thrice had occasion to remark this in patients who had been using the drug for about a fortnight, and twice in one individual; and Dr. Granville says he had also twice witnessed the same effect.[1895] As to the effects of fatal doses, it is probable that in man, as in animals, two varieties exist. When the dose is very large, death will in general take place suddenly, without convulsions. But for obvious reasons the symptoms in such cases have not been hitherto witnessed. The most complete account of the symptoms from fatal doses when convulsions occur, is given in a case reported by Hufeland of a man, who, when apprehended for theft, swallowed an ounce of alcoholized acid, containing about forty grains of the pure acid. He was observed immediately to stagger a few steps, and then to sink down without a groan, apparently lifeless. A physician, who instantly saw him, found the pulse gone and the breathing for some time imperceptible. After a short interval he made so forcible an expiration that the ribs seemed drawn almost to the spine. The legs and arms then became cold, the eyes prominent, glistening, and quite insensible; and after one or two more convulsive expirations he died, five minutes after swallowing the poison.[1896] In Horn’s Journal is recorded another case which also proved fatal in five minutes, with precisely the same symptoms.[1897] A short notice of what appears to have been a similar case is given in the Annales de Chimie. The person was a chemist’s servant, who swallowed a large quantity of the alcoholic solution by mistake for a liqueur, the poison having been accidentally left on the table by her master, who had been showing it as a curiosity to some friends. No account is given of the symptoms, farther than that she died apoplectic in two minutes.[1898] To these cases may be also added a short notice of the French physician’s case mentioned at the commencement of this chapter. It will convey a good idea of the operation of the poison when not quite sufficient to kill. Very soon after swallowing a tea-spoonful of the diluted acid he felt confusion in the head, and soon fell down insensible, with difficult breathing, a small pulse, a bloated countenance, dilated insensible pupils, and locked jaw. Afterwards he had several fits of tetanus, one of them extremely violent. In two hours and a half he began to recover his intellects and rapidly became sensible; but for some days he suffered much from ulceration of the mouth and violent pulmonary catarrh, which had evidently been excited by the ammonia given for the purpose of rousing him. This gentleman had eructations with the odour of the acid three or four hours after he took it; and during the earlier symptoms the same odour was exhaled by his breath.[1899] The hydrocyanic odour of the breath is of course an important distinguishing character, which would appear, from the observations of Dr. Lonsdale on animals,[1900] to occur more frequently than might be supposed from the silence observed on the subject by the reporters of cases. Hydrocyanic acid is not considered a cumulative poison,—that is, the continued use of frequent small doses is not believed to possess the power recognised in iodine, mercury, and foxglove, of gradually and silently accumulating in the body, and then suddenly breaking out with dangerous or fatal violence. The frequent experience of practitioners in this and other countries seems to prove that hydrocyanic acid possesses no such property. It is right at the same time to mention, that a case published by Dr. Baumgärtner of Freyburg has been thought by some[1901] to establish the reverse. A man had taken for two months, on account of chronic catarrh, ten drops of Ittner’s acid daily in doses of one grain, without experiencing the slightest toxicological effect. At length he was found one morning in bed apparently labouring under the poisonous operation of the acid. He had headache, blindness, dilated insensible pupil, feeble irregular pulse, occasional suspension of the breathing, and rapidly increasing insensibility. The cold affusion and ammonia were immediately resorted to, and at first with advantage. But in no long time spasms commenced in the toes, and gradually affected the rest of the body, till at length violent fits of general tetanus were formed, lasting for six or ten minutes, and alternating in the intervals with coma. Venesection was next resorted to; after which the spasms were confined to the jaw and eyes. Delirium succeeded, but was removed by a repetition of the blood-letting. At four in the afternoon he was tolerably sensible; during the night delirium returned; at ten next morning he recovered his sight; and on the subsequent morning he had no complaint but headache and pain in the eyes.[1902] This case differs so much from every other in the collateral circumstances, as well as in duration, that, although the symptoms themselves correspond with those of poisoning with hydrocyanic acid, we may justly suspect either some other cause, or the accidental administration of too large a dose. It ought, however, to turn the attention of practitioners to the possibility of this poison acting by the accumulation of the effects of small doses frequently repeated for a great length of time. The period within which hydrocyanic acid usually proves fatal is fixed with considerable accuracy, not only by the cases observed in the human subject, but likewise by the experiments of many physiologists, and more especially those of Schubarth (p. 583). It is probable that very large doses occasion death in a few seconds; and at all events a few minutes will suffice to extinguish life when the dose is considerable; but if the individual survive forty minutes, he will generally recover. In the course of a dreadful accident which happened a few years ago in one of the Parisian hospitals, when seven epileptic patients were killed at one time by too large doses of the medicinal acid, it was found that several did not die for forty-five minutes.[1903] But the researches of Schubarth would certainly justify the expectation that recovery will take place under active treatment when the patient survives so long.—These facts may be highly important in the practice of medical jurisprudence. The period within which it begins to operate ought also to be accurately ascertained for the same reason. Indeed in a very interesting trial, which took place a few years ago in this country, the fate of the prisoner depended in a great measure on the question, within how short a time the effects of this poison must show themselves?[1904] The nature of the case was as follows: An apothecary’s maid-servant at Leicester who was pregnant by her master’s apprentice, was found one morning dead in bed; and she had obviously been poisoned with hydrocyanic acid. Circumstances led to the suspicion that the apprentice was accessary to the administration of the poison. On the other hand, it was distinctly proved that the deceased had made arrangements for a miscarriage by artificial means on the night of her death; and it was therefore represented, on the part of the prisoner, that she had taken the poison of her own accord. But the body was found stretched out in bed in a composed posture, with the arms crossed over the trunk, and the bed-clothes pulled smoothly up to the chin; and at her right side lay a small narrow-necked phial, from which about five drachms of the medicinal prussic acid had been taken, and which was corked and wrapped in paper. There naturally arose a question, whether the deceased, after drinking the poison out of such a vessel, could, before becoming insensible, have time to cork up the phial, wrap it up, and adjust the bed-clothes?[1905] To settle this point, experiments were made at the request of the judge, by Mr. Macaulay, Mr. Paget, and several other medical men of Leicester; and on the trial they, with the exception of Mr. Paget, gave it as their opinion, founded on the experiments, that the supposed acts of volition, although within the bounds of possibility, were in the highest degree improbable. The chief experiments were three in number, from which it appeared that one dog was killed with four drachms in eight seconds, another with four drachms in seven seconds, and another with four drachms and a half in three seconds; but in other experiments the interval was greater.—For these particulars I am indebted to Mr. Macaulay. In the first edition of this work I expressed my concurrence with the majority of the witnesses. But some facts, which came subsequently under my notice, led me to think that this concurrence was given rather too unreservedly. I still adhere so far to my original views as to think it improbable that, if the deceased, after swallowing the poison, had time to cork the phial, wrap it in paper, pull up the bed-clothes, and place the bottle at her side, the progress of the symptoms could have been so rapid and the convulsions so slight, as to occasion no disorder in the appearance of the body and the bed-clothes,—and I still likewise think, that after swallowing so large a dose it was improbable she could have performed all the successive acts of volition mentioned above—with ordinary deliberation. But I am informed on good authority, that some gentlemen interested in the case found by actual trial, that all the acts alluded to might be accomplished, if gone about with promptitude, within the short period, which, in some of their experiments, the witnesses found to elapse, before the action of the poison commenced. And such being the fact, we ought not perhaps to attach too great importance to the other argument I have employed,—the probability of disorder in the body and bed-clothes from the convulsions; for if the poisoning commenced very soon, the convulsions might have been slight. The results of my own experiments related in p. 582, although on the whole confirmatory of those of Mr. Macaulay and his colleagues, are nevertheless sufficient to prove that large doses occasionally do not begin to operate with such rapidity as was observed in their experiments; for in one instance four drops of concentrated acid, equivalent to two scruples of medicinal acid, did not begin to act on a rabbit for twenty seconds; and certainly, for so small an animal, two scruples are as large a dose as five drachms for a grown-up girl. The two following cases will throw some farther light on the time within which this poison begins to act on man when taken in large quantity. The first case shows, that even when an enormous dose is taken, a few simple voluntary acts may be executed before the symptoms begin. In this instance which is related by Dr. Gierl of Lindau, the dose was no less than four ounces of the acid of the Bavarian Pharmacopœia, which contains four per cent. of pure acid, and is equivalent to five ounces at least of that commonly used in Britain and France. The subject, an apothecary’s assistant, was found dead in bed, with an empty two-ounce phial on each side of the bed,—the mattrass, which is used in Germany instead of blankets, pulled up as high as the breast,—the right arm extended straight down beneath the mattrass,—and the left arm bent on the elbow.[1906] The second case proves that, although one or two acts of volition may be accomplished, the interval is so very brief that these acts can only be of the simplest kind. An apothecary’s apprentice-lad was sent from the shop to the cellar for some carbonate of potass; but he had not been a few minutes away, when his companions heard him cry in a voice of great alarm, “Hartshorn! Hartshorn!” On instantly rushing down stairs, they found him reclining on the lower steps and grasping the rail; and he had scarcely time to mutter “Prussic acid!” when he expired,—not more than five minutes after leaving the shop. On the floor of the cellar an ounce-phial was found, which had been filled with the Bavarian hydrocyanic acid, but contained only a drachm. It appeared that he had taken the acid ignorantly for an experiment; and from the state of the articles in the cellar, it was evident that, alarmed at its instantaneous operation, he had tried to get at the ammonia, which he knew was the antidote, but had found the tremendous activity of the poison would not allow him even to undo the coverings of the bottle.[1907] When the quantity of the poison is small, a much longer interval may elapse before the commencement of its action. Thus, when the dose is barely short of what is required to occasion death, the effects may be postponed even for fifteen minutes, as in a case which occurred to Mr. Garson of Stromness.[1908] This, so far as I am at present aware, is the extreme limit of interval hitherto observed. In the trial related above the prisoner Freeman was found _Not Guilty_. It is important to fix, if possible, the smallest fatal dose of hydrocyanic acid. This will vary with particular circumstances, such as the strength of the individual, and the fulness or emptiness of the stomach at the time. The cases of the Parisian epileptics, who were killed each by a draught containing two-thirds of a grain of pure acid,[1909] will supply pointed information. For, on the one hand, considering the long time they survived, it is not probable that a dose materially less would have a fatal effect on man. And on the other hand repeated instances of recovery have been observed, where the dose was as great or even greater. Thus Dr. Geoghegan had a patient who recovered from a state of extreme danger after taking two-thirds of a grain;[1910] and Mr. Banks of Lowth met with a case of recovery in similar circumstances, where the dose was very nearly a whole grain.[1911] It is almost unnecessary to add, that in man, as in animals, this poison will act violently, through whatever channel it may be introduced into the body. It has not been positively ascertained to act with force through the unbroken skin. The chemist Scharinger indeed was supposed to have been killed in consequence of accidentally spilling the acid on his naked arm;[1912] but this was in all probability a mistake. Should the skin be freely exposed to the air it seems reasonable to expect that the poison will evaporate before it could act with energy; but if confined by pledgets or otherwise, a different result might ensue. Through every other surface, however, besides the unbroken skin, hydrocyanic acid acts with very great power; and it is in particular important to remember that its power is very great when inhaled, so that dangerous accidents have ensued even from its vapour incautiously snuffed up the nostrils. I have known a strong man suddenly struck down in this way; a French physician, M. Damiron, has related the case of an apothecary who remained insensible for half an hour subsequently to the same accident;[1913] and cases of the kind are more apt to occur than might at first view be thought, because, contrary to what is generally believed and stated in chemical as well as medico-legal works, its smell is for a few seconds barely perceptible, and never of the kind which these accounts would lead one to anticipate. Accidental death may readily arise from its action on a wound or an abraded surface. Sobernheim mentions that Mr. Scharring, a druggist at Vienna, was poisoned in consequence of a phial of the acid breaking in his hand and wounding it; and he expired in an hour.[1914] The only case with which I am acquainted of poisoning with the artificial compounds of hydrocyanic acid is that formerly alluded to as having been occasioned by the cyanide of potassium. Six grains dissolved in a clyster amounting to six ounces, occasioned general convulsions, palpitations, slow laboured breathing, coldness of the limbs, dilated pupil, fixing of the eyeballs, and death in one hour,—phenomena much the same with those produced by the acid itself.[1915]—Another case has been published, in which a French physician, ignorant of the correct dose, prescribed a potion with three grains of cyanide of potassium twice a day. Immediately after the first dose the patient was seized with the usual symptoms of poisoning with hydrocyanic acid; and expired in three-quarters of an hour.[1916] In noticing the first of these cases, Orfila draws the attention of practitioners particularly to the fact, that not long before a similar dose of a sample of cyanide, which had been moist for some time, was twice administered with impunity. The reason is that the cyanide of potassium undergoes decomposition when acted on by water, or when long kept. SECTION III.—_Of the Morbid Appearances produced by Hydrocyanic Acid._ Under this head the appearances in a special case will first be mentioned, and then the varieties to which they are liable. In _Hufeland’s_ case [p. 587] the inspection was made the day after death. The eyes were still glistening, like those of a person alive; but the countenance was pale and composed like one asleep. The spine and neck were stiff, the belly drawn in, the back alone livid. The body generally, the blood even within the head, and especially the serous cavities, exhaled a hydrocyanic odour, so strong as to irritate the nostrils. The blood was every where very fluid, so that two pounds flowed from the incision in the scalp and twelve ounces from that of the dura mater; and it had a glimmering bluish appearance, as if Prussian blue had been mixed with it. The vessels of the brain were gorged, the substance of the brain natural, and the left ventricle distended with half an ounce of serum. The villous coat of the stomach was red, easily removed with the nail, and gangrenous.[1917] The intestines were reddish, and the liver gorged. The lungs were also turgid, and to such a degree in the depending parts as to resemble the liver. The arteries and left cavities of the heart were empty, the veins and right cavities distended. In commenting on this description it is first to be remarked, that the blood, as in the preceding case, is generally altered in nature. Ittner, who made some good experiments on the subject, found it in animals black, viscid, and oily in consistence.[1918] Emmert found it fluid and of a cochineal colour. In a case related by Mertzdorff of an apothecary’s apprentice, who was found dead in bed after swallowing three drachms and a half of diluted acid,[1919] in the case recorded in Horn’s Archiv, and in that related by Dr. Gierl, it was fluid. It was also perfectly fluid every where in the bodies of the seven epileptic patients poisoned at Paris. Yet this state is not invariable. Coullon, though his results tally in general with those of Ittner and Emmert, has given some experiments in which the blood coagulated after flowing from the body;[1920] and in the case of an apothecary related in Rust’s Journal it was found coagulated in the heart.[1921] In the next place, Magendie and other physiologists have observed that, as in Hufeland’s case, the blood and cavities of the body in animals exhale a hydrocyanic odour, even though the quantity taken was small. The blood did so likewise in the heart of the apothecary just mentioned as well as throughout the whole body in the case described in Horn’s Journal. The odour, however, is not always present. For example, there was none in the case of another German apothecary, who poisoned himself with an ounce, as recorded in a later volume of Rust’s Journal;[1922] neither was there any odour in the blood in Mertzdorff’s case, although it was strong in the stomach; nor in the blood nor any other part of the body in the Parisian epileptics. It also appears from an experiment by Schubarth,[1923] and from a case by Leuret where life was prolonged above fifteen minutes,[1924]—that the odour may be distinct in the blood, brain, or chest, when hardly any is to be perceived in the stomach. Schubarth has inquired with some care into the circumstances under which the hydrocyanic odour may, or may not, be expected. He states, as the result of his researches, that if the dose is sufficient to cause death within ten minutes, the peculiar odour will always be remarked in the blood of the heart, lungs, and great vessels, provided the body have not been exposed to rain or to a current of air, and the examination be made within a moderate interval,—for example, twenty-one hours for so small an animal as a dog; but that, if the dose is so small that life is prolonged for fifteen, twenty-seven, or thirty-two minutes, then even immediately after death it may be impossible to remark any of the peculiar odour, evidently because, as already mentioned, the acid is rapidly discharged by the lungs; and that even when the dose is large enough to cause death in four minutes, the smell may not be perceived if the carcase has been left in a spacious apartment for two days, or exposed to a shower for a few hours only. These facts explain satisfactorily why no odour could be perceived in the bodies of the Parisian epileptics; for they lived from half an hour to forty-five minutes. The poison may exist in the stomach, though not appreciable by the sense of smell. In Chevallier’s case mentioned above, the contents of the stomach had not any odour of hydrocyanic acid; which, however, was evident to the sense of smell, and plainly indicated by various tests, in the fluid obtained by distilling the contents. The presence of this odour in the blood may be accounted strong evidence of poisoning with hydrocyanic acid, if it is unequivocal to the sense of several individuals. An exhalation of the same kind is occasionally formed by natural processes in the excrement. Itard once remarked in a case of inflammation of the intestines, and again in a case of inflamed liver, a strong smell of bitter almonds in the fæces, although no medicine containing hydrocyanic acid had been given.[1925] Mr. Taylor mentions that he once observed a sort of hydrocyanic odour in the brain of a person who died of natural disease.[1926] These facts will render the inspector cautious, but can scarcely throw a doubt over evidence derived from an unequivocal hydrocyanic odour in the blood. Few successful attempts have yet been made to detect the acid in the blood by chemical analysis. The odour may be present, although chemical analysis fails in eliciting any indication. This follows from the observations of Dr. Lonsdale,[1927] as well as of various authors quoted by him in his paper. The cyanide of potassium has been detected by Mayer not merely in the blood, but likewise in the serous secretions and sundry soft solids.[1928] In most instances,—for example, in the Parisian epileptics, the state of the brain, as to turgescence of vessels, has corresponded with the description given by Hufeland. Venous turgescence and emptiness of the arterial system are commonly remarked throughout the whole body. Thus in the epileptic patients, the heart and great arteries were empty; the great veins gorged; the spleen gorged, soft, and pultaceous; the veins of the liver gorged; and the kidneys of a deep violet colour, much softened, and their veins gorged with black blood. It is impossible that hydrocyanic acid could cause gangrene of the stomach, which is said to have been witnessed in Hufeland’s case. But there are often signs of irritation in that organ. The villous coat has been found red in animals; it was shrivelled, and its vessels were turgid with black blood in the instance of the apothecary mentioned in the fourteenth volume of Rust’s Journal; in Mertzdorff’s case it was red and checkered with bloody streaks; and in the case related by Dr. Gierl, where four ounces were swallowed, it was dark-red, as it were tanned or steeped in spirits, and easily separated from the subjacent contents. The contents of the stomach have in every instance had a strong hydrocyanic odour, except in the cases of the Parisian epileptics, and in those related by Leuret and by Chevallier. According to the experiments of Lassaigne and Schubarth, formerly noticed, it is not to be looked for when the body has been kept a few days, more especially if the individual lived some time. Dr. Lonsdale generally found it eight or nine days after death in animals, which had been either buried during that time, or kept in an apartment at the temperature of 50° F.[1929] In a case which occurred not long ago in London the poison was found in the stomach five days after death. A coroner’s inquest had terminated in a verdict of natural death. But suspicions having arisen, that the man had poisoned himself in anticipation of a charge of forgery, another inquiry was made; when the odour of hydrocyanic acid was evolved from the contents of the stomach, and the distilled water obtained from them yielded decisive chemical evidence of its being present.[1930] It is important to observe, in reference to the evidence of hydrocyanic acid in the stomach, that here, as in the instance of the blood, the odour may be strong, and yet the poison may not be discoverable by analysis. This fact rests on the united testimony of Coullon, Vauquelin, Leuret, Turner, and Dr. Lonsdale; the last of whom mentions that he could not detect it chemically after the fourth day in the bodies of some animals, in which it was perceptible by its odour even four or five days later.[1931] It is possible, however, that these failures to detect the poison by analysis may have sometimes arisen from imperfections in the method of analysis employed; for it was detected by the process formerly mentioned in the stomach of the apothecary last alluded to, in Chevallier’s case, though not perceptible to the smell, and frequently by Lassaigne in animals. Mertzdorff remarked both in his case of poisoning with hydrocyanic acid, and likewise in a parallel instance of poisoning with the essential oil of bitter almonds,[1932] a singular appearance in the bile, the colour of which was altered to deep blue. Coullon and Emmert say they have observed, that the bodies of animals resist putrefaction. The latter in particular mentions, that he had left them several days in a warm room without perceiving any sign of decay. This certainly would not _à priori_ be expected, considering the state of the blood. And it is not universal; for in one instance, the case of Mertzdorff, putrefaction commenced within thirty hours after death. In the Parisian epileptics, the bodies passed through the usual stage of rigidity. It appears that even long after death the eye, as in Hufeland’s case, has a peculiar glistening and staring expression, so as to render it difficult to believe that the individual is really dead; and this appearance has been considered by Dr. Paris so remarkable, as even alone to supply “decisive evidence of poisoning by hydrocyanic acid.”[1933] But the accuracy of this opinion may be questioned. The appearance is indeed very general in cases of poisoning with preparations containing hydrocyanic acid. Besides occurring in the case of Hufeland, and in that which gave occasion to Dr. Paris’s statement, it was witnessed by Mertzdorff, and in the instance described in Horn’s Journal. But it is not a constant appearance; for it was not observed in the seven Parisian epileptics. Neither is it peculiar; for death from carbonic acid has the same effect; I have remarked it six hours after death in a woman who died of cholera; and it has been observed in cases of death during the epileptic paroxysm. SECTION IV.—_Of the Treatment of Poisoning with Hydrocyanic Acid._ Much attention has been lately paid to the treatment of this variety of poisoning; and the object of those who have studied it has naturally been the discovery of an antidote. An antidote to hydrocyanic acid must either be a substance which renders it immediately insoluble, or one which exerts upon the body an action contrary to that excited by the poison, that is, a powerful stimulant action on the nervous system. Hence all such remedies as oil, milk, soap, coffee, treacle, turpentine, at one time thought serviceable, are quite inert.[1934] Antidotes have hitherto been chiefly sought for among the powerful, diffusible stimulants. And it is plain, that even although a chemical antidote were known, a stimulant antidote is indispensable also, because the mischief done, before the poison can be rendered inert, is generally sufficient to cause death, unless counteracted by treatment. Of the diffusible stimulants, _ammonia_ is considered by many the most energetic antidote. The first who made careful experiments with it was Mr. John Murray of London; and he was so convinced of its efficacy, that he expressed himself ready to swallow a dose of the acid large enough to prove fatal, provided a skilful person were beside him to administer the antidote.[1935] The favourable results obtained by Murray were afterwards confirmed by M. Dupuy.[1936] Afterwards, however, the efficacy of ammonia was called in question. Orfila stated in the third edition of his Toxicology that he had several times satisfied himself of the complete inutility of this as well as many other antidotes.[1937] And Dr. Herbst of Göttingen made some careful experiments, from which he concludes that ammonia, though useful when the dose of poison is not large enough to kill, and even capable of making an animal that has taken a fatal dose jump up and run about for a little, yet will never save its life.[1938] But farther experiments by Orfila have led him to modify his former statement, and to admit, that, although liquid ammonia is of no use when introduced into the stomach, yet if the vapour from it is inhaled, life may sometimes be preserved, provided the dose of the poison be not large enough to act with great rapidity. He remarked, that when from eight to fourteen drops of the medicinal acid were given to dogs of various sizes, they died in the course of fifteen minutes if left without assistance, but were sometimes saved by being made to inhale ammoniacal water, and recovered completely in little more than an hour.[1939] As this is very nearly the conclusion to which Mr. Murray was led by his experiments performed in 1822, it is rather extraordinary, that his name, as the undoubted discoverer of the remedy, has never been mentioned by the Parisian Professor. Buchner, it is right to add, had found this remedy useful in the same year in which Mr. Murray’s experiments were made.[1940] A gentleman who took an over-dose of two drachms of hydrocyanic acid while using it medicinally, and who seems to have been in great danger, owed his recovery to the assiduous use of carbonate of ammonia held to the nostrils, and spirit of ammonia internally. Relief was obtained immediately.[1941] Orfila suggests an important caution,—not to use a strong ammoniacal liquor, otherwise the mouth, air-passages, and even the alimentary canal may be attacked with inflammation,—as indeed happened to the French physician whose case was formerly mentioned. The strong _aqua ammoniæ_ should be diluted with several parts of water. Another remedy of the same kind with ammonia as to action is _chlorine_. This substance was first proposed as a remedy in 1822 by Riauz, a chemist of Ulm, who found that, when a pigeon, poisoned with hydrocyanic acid, was on the point of expiring, it immediately began to revive, on being made to breathe chlorine, and in fifteen minutes was able to fly away.[1942] Buchner repeated Riauz’s experiments and arrived at the same results. More lately M. Simeon, apothecary to the hospital of St. Louis at Paris, apparently without being acquainted with the observations of the German chemists, was likewise led to suppose, that this gas might prove a useful antidote;[1943] and MM. Cottereau and Vallette have formed the same conclusion.[1944] Orfila in his paper already quoted expresses his conviction, that this remedy is the most powerful antidote of all hitherto proposed. His experiments have convinced him, that animals, which have taken a dose of poison sufficient to kill them in fifteen or eighteen minutes, will be saved by inspiring water impregnated with a fourth part of its volume of chlorine, even although the application of the remedy be delayed till the poison has operated for four or five minutes. In some of his experiments he waited till the convulsive stage of the poisoning was passed, and the stage of flaccidity and insensibility had supervened; yet the animals were obviously out of danger ten minutes after the chlorine was first applied, and recovered entirely in three-quarters of an hour.[1945] The last remedy of this nature which deserves notice is the _cold affusion_. This was first recommended by Dr. Herbst of Göttingen, who, on account of the success he witnessed from it in animals, considers it the best remedy yet proposed. When the dose of the poison was insufficient to prove fatal in ordinary circumstances, two affusions he found commonly sufficient to dispel every unpleasant symptom. When the dose was larger, it was necessary to repeat the effusion more frequently. Its efficacy was always most certain when resorted to before the convulsive stage of the poisoning was over; yet even in the stage of insensibility and paralysis it was sometimes employed with success. In the latter instance the first sign of amendment was renewal of the spasms of the muscles. Many experiments are related by the author in support of these statements. But the most decisive is the following. Two poodles of the same size being selected, hydrocyanic acid was given to one of them in repeated small doses till it died. The whole quantity administered being seven grains of Ittner’s acid, this dose was given at once to the other dog. Immediately it fell down in convulsions, violent opisthotonos ensued, and in half a minute the convulsive stage was followed by flaccidity, imperceptible respiration, and failing pulse. The cold affusion was immediately resorted to, but at first without any amendment. After the second affusion, however, the opisthotonos returned, and was accompanied by cries; and on the remedy being repeated every fifteen minutes, the breathing gradually became easier and easier, the spasms abated, and in a few hours the animal was quite well.[1946] Professor Orfila repeated Dr. Herbst’s experiments, with analogous results; but he considers the cold affusion inferior to chlorine.[1947]—It is probably advantageous to apply the cold water rather in the form of cold douche to the head and spine than to the body at large. Dr. Robinson of Sunderland found that rabbits, which had taken doses adequate to occasion death, might be saved by pouring on the hindhead and along the spine cold water impregnated with common salt and nitre.[1948] A case, which seems to have been cured in this way, has been published by Mr. Banks of Lowth. A young woman took by mistake a solution containing very nearly a grain of real acid, and immediately became insensible and convulsed. Ordinary stimulants were of no use. But in fifteen minutes, when the convulsions had ceased, and she lay in a state of complete coma and general paralysis, the cold douche on the head first renewed the convulsions, then strengthened the pulse and restored some appearance of consciousness, and finally roused her, so that in a few hours she was quite well.[1949] It is probable, that _bleeding from the jugular vein_ deserves more attention as a remedy than it has yet received. The right side of the heart is almost invariably found much gorged with blood in animals examined at the moment of death; and the contractions of the heart, in such circumstances imperfect or arrested altogether, have often been observed by experimentalists to be instantly restored on promptly removing the state of turgescence. Accordingly Dr. Cormack found that a dog, at the point of death after receiving a fatal dose of the acid, was speedily roused and eventually saved by bleeding from the jugular vein.[1950] And in a careful inquiry by Dr. Lonsdale, it was ascertained that the turgescence of the heart might be effectually diminished in this way, and that recovery might frequently be accomplished when the poison was otherwise amply sufficient to have occasioned speedy death.[1951] In a case treated by Magendie, that of a young lady poisoned by too large a medicinal dose, the chief remedies were ammonia and blood-letting from the jugular vein; and she recovered.[1952] Few observations have hitherto been made on the chemical antidotes for hydrocyanic acid, or those substances which render it innoxious by converting it into an insoluble compound. It is plain that several probable antidotes of this kind exist. But toxicologists have been apparently deterred from trying them by the fearful rapidity with which the poison acts, and the consequent improbability that in practice any such antidote can be administered in time. It has lately been shown, however, by Messrs. T. and H. Smith of this city, that the effects of a fatal dose may be warded off by the timely administration of the reagents necessary for converting the acid into Prussian blue. They found that if a solution of carbonate of potash followed by a solution of the mixed sulphates of iron be given to animals very soon after the administration of a dose of thirty drops of the Edinburgh medicinal acid, containing three per cent. of real acid, recovery in general takes place, and sometimes little inconvenience seems to be sustained. The solutions they used were one of 144 grains of carbonate of potash in two ounces of water, and another composed of a drachm and a half of sulphate of protoxide of iron, together with two drachms of the same salt converted into sulphate of sesquioxide by means of sulphuric and nitric acids in the usual way. About 52 minims of each of these solutions will remove the whole acid contained in 100 grains of the Edinburgh medicinal acid; but for certainty, three or four times as much should be used,—which may be done with perfect safety.[1953] On the whole, then, it appears that the proper treatment of a case of poisoning with hydrocyanic acid consists in the cold affusion applied to the head and spine, the inhalation of diluted ammonia or chlorine, venesection at the jugular vein, and the administration of carbonate of potash and the mixed sulphates of iron, if aid has been obtained in good time. It is right to remember, however, that on account of the dreadful rapidity of this variety of poisoning, it will rarely be in the physician’s power to resort to any treatment soon enough for success;—and farther, that his chance of success must generally be feeble even though the case be taken in time, because when hydrocyanic acid is swallowed by man, the dose is commonly so large as not to be counteracted by any remedies. _On the Vegetable Substances which contain Hydrocyanic Acid._ Hydrocyanic acid exists in several plants; which are consequently poisonous. I have considered it advisable to describe their effects separately from those of the pure acid. The plants which have been thoroughly examined and found to yield it belong chiefly to the division _Drupaceæ_, of Decandolle’s Natural Family the _Rosaceæ_. These are the bitter almond, cherry-laurel, bird-cherry, and peach. The leaves and seeds of the nectarine and apricot, and the seeds of the plum and cherry, have the same taste with these four, and therefore will certainly be found to contain the acid also. The same inference may be drawn from the taste of some pomaceous seeds; and accordingly I have obtained a hydrocyanated oil from the seeds of the New York pippin, and those of the white-beam-tree, the _Pyrus aria_. The poison procured from these sources exists in two forms,—as a distilled water, and as an essential oil. Further, the acid has been discovered to constitute the active poison of the juice of the _Janipha manihot_, or bitter cassava [see p. 457]. The distilled waters yield hydrocyanic acid, as is shown by the blue precipitate they give with potass and the mixed sulphates of iron. They have a powerful, peculiar, grateful odour, which is usually likened to that of pure hydrocyanic acid. But the smell really bears very little resemblance to that of hydrocyanic acid, and is not owing to its presence: the odour remains equally strong after the acid is thrown down by the test now mentioned. The active part of the distilled water may be separated in the form of a volatile oil. This is colourless at first, afterwards yellowish or reddish, acrid, bitter, heavier than water, and very volatile. The essential oil of the bitter almond has been carefully examined by various chemists. Vogel, by subjecting it twice to distillation from caustic potass, procured hydrocyanate of potass in the residue; and a volatile oil was distilled over, which no longer contained hydrocyanic acid, but nevertheless had the odour of the original oil.[1954] This purified oil he considered equally poisonous with that which contains hydrocyanic acid, a single drop of it having killed a sparrow; and his opinion was confirmed by the experiments of Professor Orfila. But according to some careful experiments by Stange,[1955] which have been amply confirmed by Dr. Göppert of Breslau,[1956] and also by MM. Robiquet and Boutron-Charlard,[1957]—if the purified oil retains active poisonous properties, this must be owing to the acid not having been entirely removed. Göppert in particular remarked that twenty-five drops of the purified bitter-almond oil, cherry-laurel oil, or bird-cherry oil had very little effect on rabbits, not more indeed than the same quantity of the common essential oils. The purified oil, according to all these chemists, possesses the odour of the original oil, as Vogel first stated. _Of the Bitter Almond._ The bitter almond was once extensively used in medicine, and is still much employed by confectioners for flavouring puddings, sweetmeats, and liqueurs. It is the kernel of the fruit of the _Amygdalus communis_. This species has two varieties, the _dulcis_ and the _amara_; which differ from one another in the fruit only. The fruit of the former yields the sweet, and of the latter the bitter almond. The bitter almond is the smaller of the two. The two plants, according to Murray, are convertible into each other,—the sweet variety becoming bitter by neglect,—the bitter becoming sweet by cultivation, or certain modes of management not well known,—and the seed of either variety producing plants of both.[1958] These statements as to the mutual convertibility of the two varieties require confirmation. The bitter almond depends for its activity on the essential oil, which is common to all the vegetable poisons belonging to the present tribe. According to the researches of Robiquet and Boutron-Charlard, followed up by Liebig, the oil does not, like common essential oils, exist ready formed in the almond, but is only produced when the almond-pulp comes in contact with water. It cannot be separated by any process whatever from the almond without the co-operation of water,—neither, for example, by pressing out the fixed oil, nor by the action of ether, nor by the action of absolute alcohol. After the almond is exhausted by ether, the remaining pulp gives the essential oil as soon as it is moistened; but if it is also exhausted by alcohol, the essential oil is entirely lost. The reason is that alcohol dissolves out a peculiar crystalline principle, named amygdalin, which, with the co-operation of water, forms the essential oil by reacting on a variety of the albuminous principle in the almond, called emulsion or synoptase. In some respects, therefore, the essential oil of almonds is quite peculiar in its nature, and quite different from the common essential or volatile oils.—The presence of hydrocyanic acid in it is easily proved by dissolving it with agitation in water, and treating the solution with caustic potass, followed by the mixed sulphates of iron and sulphuric acid.—The quantity of essential oil which may be procured from the bitter almond amounts, according to Krüger of Rostock, to four drachms from five pounds or a ninety-sixth part.[1959] The quantity of hydrocyanic acid in the oil varies considerably: Schrader got from an old sample 8·5 per cent., from a new sample 10·75;[1960] but Göppert got from another specimen so much as 14·33 per cent.[1961] _Effects on Animals._—The bitter almond is a powerful poison, which acts in the same way as hydrocyanic acid, but likewise excites at times vomiting and other signs of irritation. The first good experiments on it are those related in Wepfer’s treatise on the Cicuta; but its properties seem to have been known even to Dioscorides. The symptoms it induces in animals are trembling, weakness, palsy, convulsions, often of the tetanic kind, and finally coma. But frequently it occasions vomiting before these symptoms begin, and the animal in that way may escape.[1962] According to Orfila, twenty almonds will kill a dog in six hours by the stomach if the gullet be tied; and six will kill it in four days when applied to a wound.[1963] The essential oil is not much inferior in activity to the pure hydrocyanic acid. A single drop of it applied by Sir B. Brodie on the tongue of a cat caused violent convulsions and death in five minutes.[1964] But more generally a larger dose, or about seven drops, has been found necessary to kill a middle-sized dog. Five drops, according to Göppert, will kill a rabbit in six minutes. When entirely freed of hydrocyanic acid, it becomes, as already mentioned, not more poisonous than common volatile oils. _Symptoms in Man._—The effects of the almond and of the oil upon man are equally striking with those of hydrocyanic acid. In small doses the bitter almond produces disorder of the digestive organs, nausea, vomiting, and sometimes diarrhœa. These symptoms are occasionally brought on by the small quantities used for flavouring sweetmeats, if the confectioner has not been careful in compounding them. Virey says that accidents occasionally happen to children at Paris from their eating freely of macaroons, which are sometimes too strongly flavoured with the bitter almond.[1965] In this country accidents from the same cause may be with justice apprehended, as confectioners now generally use, not the bitter almond, but its essential oil, which is distilled for the purpose in London, and sold in the druggists shops under the name of peach-nut oil. Göppert suggests that this oil ought to be freed of its hydrocyanic acid by repeated distillation with caustic potassa, because the flavour is not in the least injured by the process, while its activity as a poison is greatly lessened. In peculiar constitutions the minutest quantity, even a single almond, will cause a state resembling intoxication, succeeded by an eruption like nettle-rash. The late Dr. Gregory was subject to be affected in this way. Other vegetable bitters had the same effect on him, but none so remarkably as bitter almonds. They caused first sickness, generally tremors, then vomiting, next a hot fit with an eruption of urticaria, particularly on the upper part of the body. At the same time the face, and head swelled very much, and there was generally a feeling like intoxication. The symptoms lasted only for a few hours. The rash did not alternately appear and disappear as in common nettle-rash.[1966] A lady of my acquaintance is liable to be attacked with urticaria even from eating the sweet almond. The quantity of bitter almonds which may be eaten with impunity is unknown; but Wibmer mentions an experimentalist who took half an ounce without any other effect besides headache and sickness.[1967] Two cases of death in the human subject from eating them have been quoted by Coullon from the Journal de Médecine of Montpellier. One is a doubtful case, but the other is unequivocal. A bath-woman gave her child the “expressed juice” of a handful of bitter almonds to cure worms. The child, who was four years old, was immediately attacked with colic, swelling of the belly, giddiness, locked jaw, frothing at the mouth, general convulsions, and insensibility, and died in two hours.[1968] Murray, however, asserts in his Apparatus Medicaminum that the expressed juice is sweet and not poisonous.[1969] But this apparent contradiction is easily explained by referring to the chemical relations of the almond,—the oil expressed without water being free from essential oil, while the milky fluid expressed from the pulp beat up with water is strongly impregnated with it.—Another case was published not long ago by Mr. Kennedy of London; but the symptoms were imperfectly ascertained. The person, a stout labourer, appeared to have eaten a great quantity of bitter almonds, which were subsequently found in the stomach. He was seen to drop down while standing near a wall; soon after which the surgeon who was sent for found him quite insensible, with the pulse imperceptible, and the breath exhaling the odour of bitter almonds; and death took place in no long time.[1970] Coullon has noticed many other instances where alarming symptoms were produced by this poison, but were dissipated by the supervention of spontaneous vomiting. The effects of small doses of the oil have been tried by Sir B. Brodie on himself; and a fatal case of poisoning with it has been recorded by Mertzdorff. In the course of his experiments Sir B. Brodie once happened to touch his tongue with the end of a glass rod which happened to be dipped in the oil; and he says he had scarcely done so before he felt an uneasy, indescribable feeling in the pit of the stomach, great feebleness of his limbs, and loss of power to direct the muscles, so that he could hardly keep himself from falling. These sensations were quite momentary.[1971] Mertzdorff’s case is interesting, not only as being accurately related, but likewise on account of the exact resemblance of the symptoms to those observed in the celebrated case of Sir Theodosius Boughton, which will presently be mentioned. A hypochondriacal gentleman, 48 years old, swallowed two drachms of the essential oil. A few minutes afterwards, his servant, whom he sent for, found him lying in bed, with his features spasmodically contracted, his eyes fixed, staring, and turned upwards, and his chest heaving convulsively and hurriedly. A physician, who entered the room twenty minutes after the draught had been taken, found him quite insensible, the pupils immoveable, the breathing stertorous and slow, the pulse feeble and only 30 in a minute, and the breath strongly impregnated with the odour of bitter almonds, death ensued ten minutes afterwards.[1972] A fatal case occurred lately in London, where the individual, intending to compound a nostrum for worms with beech-nut oil, got by mistake from the druggist peach-nut oil, which is nothing else than the oil of bitter almond.—A singular case of recovery from a very large dose of this poison has been lately published by M. Chevasse. A shopkeeper, who swallowed half an ounce by mistake for spirit of nitric ether, had an attack of spontaneous vomiting, which was forthwith encouraged by sulphate of zinc. He nevertheless became pale and convulsed; the pulse disappeared; and delirious muttering ensued, with _risus sardonicus_, sparkling of the eyes, and panting respiration. Recovery, however, took place under the use of brandy and ammonia.[1973] The morbid appearances are the same as in poisoning with the pure acid. In Mertzdorff’s case the whole blood and body emitted a smell of almonds; putrefaction had begun, though the inspection was made twenty-nine hours after death; the blood throughout was fluid, and flowed from the nostrils and mouth; the veins were every where turgid; the cerebral vessels gorged; the stomach and intestines very red.—In the case from the Medical and Physical Journal of poisoning with the almond itself, the vessels of the brain were much gorged, and the eyes glistening and staring as if the person had been alive. _Of the Cherry-Laurel._ The cherry-laurel, or _Cerasus lauro-cerasus_, was at one time much used for flavouring liqueurs and sweetmeats. But it is now less employed than formerly, as fatal accidents have happened from its having been used in too large quantity. The custom, however, has not been altogether abandoned; for there is an account in an English newspaper in 1823 of two persons killed by ratifia’d brandy, which had been flavoured with this plant; and Dr. Paris has mentioned an instance of several children at an English boarding-school having been dangerously affected by a custard flavoured with the leaves.[1974] Almost every part of the plant is poisonous, especially the leaves and kernels; but the pulp of the cherry is not. The flower has a totally different odour from the leaves. The healthy vigorous shoots in the early part of summer, and the inner bark, both then and in autumn, smell strongly of the bitter almond when broken across. The kernels of the seeds have a strong taste of bitter almonds.—The plant yields a distilled water and an essential oil, which Robiquet found to have all the chemical properties of the oil of bitter almond.[1975]—A very peculiar source of danger in using the leaves of this plant, for imparting a ratafia flavour to sweetmeats and liqueurs, is that the proportion of oil varies excessively according to the age of the leaf. It abounds most in the young undeveloped leaves, and diminishes gradually afterwards. Hence, the leaves being evergreen and outliving more than two summers, the young leaves in May or June contain, as I have found, nearly ten times as much oil as the old ones at the same moment. Cherry-laurel oil, according to Schrader, contains 7·66 per cent. of hydrocyanic acid;[1976] but according to Göppert, a specimen supposed to be genuine gave only 2·75 per cent.[1977] It is probably therefore a weaker poison than the oil of bitter almond. The latest experiments made with this oil are those of some Florentine physicians, performed at the laboratory of the Marquess Rodolphi, and described by Professor Taddei.[1978] Sixteen drops put on the tongue of rabbits killed them in nine, fifteen, or twenty minutes; and ten or twelve drops injected in oil into the anus killed them in four minutes. The symptoms were slow breathing, palsy of the hind-legs, then general convulsions; and death was preceded by complete coma. A very extraordinary appearance was found in the dead body,—blood extravasated abundantly in the trachea and lungs. The cherry-laurel water, prepared by distillation from the leaves of this plant, was long the most important of the poisons which contain the hydrocyanic acid, as it was the most common before the introduction of the acid itself into medical practice. Water dissolves by agitation 3·25 grains of oil per ounce; which may be considered the proportion in a saturated distilled water. The water contains, according to Schubarth, only 0·25 per cent. of hydrocyanic acid;[1979] according to Schrader[1980] only half as much; and by long keeping even that small proportion will gradually disappear, as I have ascertained by experiment. Hence its strength must vary greatly,—a fact which will explain the very different effects of the same dose in different instances. From experiments on animals by a great number of observers, it appears that, whether it is introduced into the stomach, or into the anus, or into the cellular tissue, or directly into a vein, it occasions giddiness, palsy, insensibility, convulsions, coma, and speedy death;—that the tetanic state brought on by the pure acid, is not always so distinctly caused by cherry-laurel water;—and that tetanus is most frequently induced by medium doses. The attention of physicians was first called to this poison by an account, published by Dr. Madden in the Philosophical Transactions for 1737, of several accidents which occurred at Dublin in consequence of strong ratifia’d brandy having been prepared with it. Foderé has also given an account of two cases, caused by servants having stolen and drunk a bottle of it, which they mistook for a cordial.[1981] Being afraid of detection, they swallowed it quickly, and in a few minutes expired in convulsions. Murray has noticed several others in his Apparatus Medicaminum.[1982] In most of these cases the individuals suddenly lost their speech, fell down insensible, and died in a few minutes. Convulsions do not appear to have been frequent. Coullon has also related an instance where a child seems to have been killed by the leaves applied to a large sore on the neck.[1983] The dose required to occasion these effects, and more especially to prove fatal, has not been determined with care. It must vary with the age of the sample used. It will vary also according as the water has been filtered or not; for what is not filtered often presents undissolved oil suspended in it or floating on its surface. One ounce has proved fatal;[1984] and half an ounce has caused only temporary giddiness, loss of power over the limbs, stupor, and sense of pressure in the stomach.[1985] The appearances found in the dead body have varied. In general the blood has been fluid. The smell of bitter almond has commonly been distinct in the stomach. The cherry-laurel water has attracted much attention in this country, in consequence of being the poison used by Captain Donnellan for the murder of Sir Theodosius Boughton. The trial of Donnellan, the most important trial for poisoning which ever took place in Britain, has given rise to some discrepance of opinion both among barristers and medical men, as to the sufficiency of the evidence by which the prisoner was condemned.[1986] For my part, taking into account the general, as well as medical circumstances of the case, I do not entertain a doubt of his guilt. Leaving the general evidence out of view, however, as foreign to the objects of the medical jurist’s regard, it must be admitted that the medical evidence, taken by itself, was defective. It may be summed up shortly in the following terms:—Sir Theodosius was a young man of the age of twenty, and in perfect health, except that he had a slight venereal complaint of old standing, for which he occasionally took a laxative draught. On the morning of his death, his mother, Lady Boughton, remarked, while giving him his draught, that it had a strong smell of bitter almonds. Two minutes after he took it, she observed a rattling or gurgling in his stomach; in ten minutes more he seemed inclined to doze; and five minutes afterwards she found him quite insensible, with the eyes fixed upwards, the teeth locked, froth running out of his mouth, and a great heaving at his stomach and gurgling in his throat. He died within half an hour after swallowing the draught. The body was examined ten days after death, and the inspectors found great congestion of the veins every where, gorging of the lungs, and redness of the stomach. But the examination was unskilfully conducted. For the head was not opened; the fæces were allowed to rush from the intestines into the stomach; and, as a great quantity of fluid blood was found in each cavity of the chest, the subclavian veins must have been divided during the separation of the clavicles. Very little reliance, therefore, can be placed in the evidence from the inspection of the body.[1987] On comparing these particulars with what has been said above regarding the effects of hydrocyanic acid and this whole genus of poisons, it will be seen that every circumstance coincides precisely with the supposition of poisoning with the cherry-laurel water. The symptoms were exactly the same as in Mertzdoff’s case of poisoning with the essential oil of almonds (p. 604). When to this are added, the smell of the draught, which Lady Boughton could hardly mistake, the rarity of apoplexy in so young and healthy a person as Sir Theodosius, and the improbability of either that or any other disease of the head proving fatal so quickly,—the conclusion at which, in my opinion, every sound medical jurist must arrive is, that poisoning in the way supposed was very probable. But I cannot go along with those who think that it was certain; nor is it possible to see on what grounds such an opinion can be founded, when the general or moral circumstances are excluded. The medical evidence in Donnellan’s case has been much canvassed, and especially that of Mr. John Hunter. It would be foreign to the plan hitherto pursued in this work to analyze and review what was said by him and his brethren. But I must frankly observe, that Mr. Hunter’s evidence does him very little credit, and that his high professional eminence is the reverse of a reason for palliating his errors, or treating them with the lenity which they have experienced from his numerous critics. _Of the Peach, Cluster-Cherry, Mountain-Ash, &c._ Little need be said of the other plants formerly mentioned among those which yield hydrocyanic acid, and act on the system in consequence of containing that substance. The _Amygdalus persica_ or peach is the most active of them. Most parts of the plant exhale the odour of the bitter-almond, but particularly the flowers and kernels. According to the chemical researches of M. Gauthier, the fresh young shoots of the peach collected in July contain, weight for weight, even more essential oil than the bitter almond, or cherry-laurel leaves; for 250 grains yielded nearly five grains of it or two per cent.; and he found the oil may be easily procured by distilling the shoots without addition till the product begins to pass over clear.[1988] The kernels of the peach, when distilled with water, yield nearly one grain of hydrocyanic acid per ounce.[1989] Coullon has collected two instances of poisoning with the peach-blossom. One is the case of an elderly gentleman, who swallowed a sallad of the flower to purge himself. Soon afterwards he was seized with giddiness, violent purging, convulsions, and stupor; and he died in three days. Here the poison must have proved fatal by inducing true apoplexy in a predisposed habit; at least poisoning with hydrocyanic acid never lasts nearly so long. The other, a child eighteen months old, after taking a decoction of the flowers to destroy worms, perished with frightful convulsions, efforts to vomit, and bloody diarrhœa.[1990] The peach-blossom would therefore appear to be rather a narcotico-acrid, than a narcotic.—Peach-leaves are represented to have produced even purely irritant effects. A man, who took a decoction of a handful boiled in a quart of water down to a third,—when of course no hydrocyanic acid could remain,—was attacked with tightness in the chest, a sense of suffocation, violent colic, pain in the stomach and frequent desire to vomit, followed by a hard pulse, restlessness, and flushing of the face. But he recovered slowly under the use of fomentations and opiates.[1991] The bark of the _Prunus padus_, or cluster-cherry, a native of this country, owes its poisonous qualities to the same substance as the preceding plants. Heumann found that the distilled water obtained from two ounces of bark in March contains two grains of acid, two ounces of developed leaves half a grain, and two ounces of the seed a trifle less.[1992] Its distilled water has the odour of bitter almonds, contains the same essential oil with that of the bitter almond, and yields more hydrocyanic acid than the cherry-laurel water.[1993] The oil, according to Schrader, contains 9·25[1994] per cent. of hydrocyanic acid, according to Göppert only 5·5 per cent.[1995] Bremer, who has examined this plant with great care, found that both the distilled water and the essential oil kill mice when put into the mouth, eye, nose, ear, anus, or a wound; and that half an ounce of the water killed a dog in twelve minutes.[1996] The fruit is also poisonous. It has a nauseous taste, but communicates a pleasant flavour to spirituous liquors. The kernels yield by expression a transparent, fixed oil, concrete at 41° F., which contains a small quantity of the essential oil; and the cake which is left yields so much of the latter, that, as we are informed by M. Chancel of Briançon, a handful has proved fatal to cows in a short time.[1997] In these kernels, as in the bitter almond, the essential oil does not exist ready formed, but is developed only in consequence of the contact of water; and hence, if the fixed oil by expression contains a little of it, as Chancel says, this must arise from the kernels having been moist when squeezed. The _Sorbus aucuparia_, mountain-ash, or Rowan-tree as it is called in Scotland, has been lately added to the list of plants which abound in the same poisonous principle. M. Grassmann of St Petersburgh has found that many parts of this tree, such as the flowers and the bark of the trunk and branches, contain more or less of the peculiar essential oil; and that the root in particular contains so much in the month of May as to smell strongly of it when broken across, and to yield a distilled water which holds fully as much hydrocyanic acid as that procured from an equal weight of cherry-laurel leaves.[1998] Several other plants of the same natural order possess similar though weaker properties, such as the _Prunus avium_, or black-cherry, or mazzard, the _Prunus insititia_, or bullace, the _Prunus spinosa_, or sloe, the _Amygdalus nana_, or dwarf-almond, and even the leaves and kernels of the common cherry, the _Cerasus communis_. Twelve ounces of cherry kernels distilled with water, yield, according to Geiseler, seven grains of hydrocyanic acid.[1999] I have no doubt, from my experiments, that the seeds of _Pyrus malus_, the apple, _Pyrus aria_, the white-beam, and also, if the taste may be taken for a criterion, the whole seeds of the _Pomaceæ_, yield by distillation with water a large quantity of hydrocyanic acid.