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A
TREATISE
ON
POISONS
IN RELATION TO
MEDICAL JURISPRUDENCE, PHYSIOLOGY, AND THE PRACTICE OF PHYSIC.

BY

ROBERT CHRISTISON, M.D., F.R.S.E.,

Professor of Materia Medica in the University of Edinburgh, Fellow of the Royal College of Physicians, &c., Member of the American Philosophical Society,—of the Royal Acad. of Med. of Paris,—of the Imp. Soc. of Physicians of Vienna,—of the Imp. Med. Chir. Acad. of St. Petersburg,—of the Med. Chir. Soc. of Berlin,—of the Med. Chir. Assoc, of Hamburg,—of the Soc. of Nat. and Phys. of Heidelberg,—of the Philadelphia Coll. of Pharm.

FIRST AMERICAN, FROM THE FOURTH EDINBURGH EDITION.

PHILADELPHIA:

ED. BARRINGTON & GEO. D. HASWELL.

1845.

PREFACE
TO THE FOURTH EDITION.

The author regrets that circumstances beyond his control have delayed the re-appearance of the present work beyond the period at which it was called for by the favourable reception of the last edition. He has endeavoured to take advantage of the numerous investigations which have been carried on during the interval into the several departments of Toxicology in the leading countries of Europe; and has in consequence been led to enlarge the work materially.

He trusts it may be allowed him to express his satisfaction at finding, that the rapid progress made by Toxicological science during the last eight years, while it has been productive of many important additions to our knowledge, has nevertheless not rendered any important alterations necessary either in the general principles formerly laid down in this work, or in what had been there stated as well ascertained general facts.

Edinburgh College,

November, 1844.

CONTENTS.

PART FIRST.
OF GENERAL POISONING.

CHAPTER I.
ON THE PHYSIOLOGICAL ACTION OF POISONS.

I shall discuss this subject by considering first the mode in which poisons act, and secondly, the causes by which their action is liable to be modified.

Section I.—On the Mode of Action of Poisons.

On attending to the effects which follow the application of a poison to the body, we perceive that they are sometimes confined to the part where it is applied, and at other times extend to distant organs. Hence the action of poisons may be naturally considered as local and remote.

The local effects of poisons are of three kinds. Some decompose chemically or corrode the part to which they are applied. Others, without immediately injuring its organization, inflame or irritate it. Others neither corrode nor irritate, but make a peculiar impression on the sentient extremities of the nerves, unaccompanied by any visible change of structure.

We have examples of local corrosion or chemical decomposition in the effects of the concentrated mineral acids or alkalis on the skin, and in the effects of strong oxalic acid, lunar caustic, or corrosive sublimate on the stomach. In all of these instances the part to which the poison is applied undergoes chemical changes, and the poison itself sometimes undergoes chemical changes also. Thus oxalic acid dissolves the gelatin of the animal textures; and in the instance of corrosive sublimate, the elements of the poison unite with the albumen, fibrin, and other principles of the tissues.

Of local irritation and its various consequences we have many examples, from redness, its slightest, to ulceration and gangrene, its most severe effect. Thus externally, alcohol reddens the skin; cantharides irritates the surface of the true skin and causes vesication; tartar-emetic causes deep-seated inflammation of the true skin and a pustular eruption; the juice of manchineel[^[1]] spreading inflammation of the subcutaneous cellular tissue; arsenic inflammation of all these textures, and also death of the part and subsequent sloughing. Internally, alcohol reddens the stomach, as it does the skin,—but more permanently; while other substances, such as the diluted mineral acids, arsenic, cantharides, euphorbium, and the like, may cause all the phenomena of inflammation in the stomach and intestines, namely, extravasation of blood, effusion of lymph, ulcers, gangrene. Many of these irritants, such as arsenic, are in common speech called corrosives; but they have not any power of causing chemical decomposition: if they produce a breach in the texture of an organ, it is merely through the medium of inflammation and its effects.

Of nervous impressions, without any visible organic change, few well authenticated and unequivocal instances are known. A good example has been mentioned by Sir B. Brodie in the effect of monkshood on the lips when chewed,[^[2]] an effect which I have also often experienced: it causes a sense of numbness and tingling in the lips and tongue, lasting for some hours, and quite unconnected with any affection of the general nervous system. Another instance, first mentioned to me by M. Robiquet, and which I have verified, occurs in the effects of the strong hydrocyanic acid: when this acid is confined in a glass tube with a finger on its open end, the point of the finger becomes benumbed, exactly as from the local action of great cold. These are undoubted instances of a purely nervous local impression on the external surface of the body. The most unequivocal instance I know of a similar impression on internal parts is a fact related by Dr. W. Philip with regard to opium.[^[3]] When this poison was applied to the inner coat of the intestines of a rabbit during life, the muscular contractions of the gut were immediately paralyzed, without the general system being for some time affected. The same effect has been observed by Messrs. Morgan and Addison to follow the application of ticunas to the intestine:[^[4]] an instant and complete suspension of the peristaltic movement took place as soon as it touched the gut. A parallel fact has also been described by Dr. Monro, secundus:[^[5]] when an infusion of opium was injected between the skin and muscles of the leg of a frog, that leg soon became palsied, while the animal was able to leap briskly on the other three. Analogous results have farther been obtained with the prussic acid by M. Coullon.[^[6]] He remarked, that when one hind-leg of a frog was plunged in the acid, it became palsied in thirty-five minutes, while the other hind-leg continued perfectly sensible and irritable. Acetate of lead probably possesses the same property.

These facts are important, because some physiologists have doubted whether any local impressions of a purely nervous nature, unconnected with appreciable organic change, may arise from the action of poisons. Yet the existence of impressions of the kind is essential to the stability of the doctrine of the sympathetic operation of poisons,—that is, of the transmission of their influence from organ to organ along the nerves. Nay, in the instance of many poisons supposed to act in that manner, we must still farther believe in the existence of primary nervous impressions, which are not only unconnected with organic change, but likewise undistinguishable by any local sign whatsoever.

Of the three varieties in the local effects of poisons—corrosion, irritation, and nervous impressions,—the first two may take place in any tissue or organ; for example, they have been observed on the skin, on the mucous membrane of the stomach, intestines, windpipe, air tubes, bladder, and vagina, in the cellular tissue, in the serous membranes of the chest and abdomen, in the muscular fibre. We are not so well acquainted with the nature of local nervous impressions on different tissues; but it is probable that in some textures of the body they are very indistinct.

So much for the local effects of poisons.

On tracing the phenomena which follow more remotely, we observe that the affected part sometimes recovers without any visible change, sometimes undergoes the usual processes consequent on inflammation, sometimes perishes at once and is thrown off; and if the organ is one whose function is necessary to life, death may gradually ensue, in consequence of that function being irrecoverably injured. The purest example of the last train of phenomena is to be seen in the occasional effects of the mineral acids or alkalis: death may take place simply from starvation, because the inner surface of the stomach and intestines is so much injured that a sufficient quantity of nutriment cannot be assimilated.

But death and its antecedents can seldom be accounted for in this way. For symptoms are often witnessed, which bear no direct relation to the local injury: death is generally too rapid to have arisen from the function of the part having been annihilated: and the rapidity of the poisoning is not proportional in different cases to the local injury produced. Even the mineral acids and alkalis seldom kill by impeding or annihilating digestion, because they often prove fatal in a few hours; and among other poisons there are few which ever cause death simply by disturbing the function of the part primarily acted on. Death and the symptoms preceding it arise from an injury of some other organ, to which they are not and cannot be directly applied. We are thus led to consider their remote action.

The term remote is here used in preference to the common phrase general action, because the latter implies an action on the general system or whole body; whereas it appears that an action of such a kind is rare, and that most poisons which have an indirect action exert it on one or more of the important organs only, and not on the general system.

There is not a better instance of the remote action of poisons than oxalic acid. It has been already mentioned that concentrated oxalic acid is a corrosive: yet it never kills by destroying the function of the stomach. Man, as well as the lower animals, will live several days or weeks without nutriment. Now this poison has been known to kill a man in ten minutes, and a dog in three minutes only. Neither does it always induce, when swallowed, symptoms of an injury of the stomach; for death is often preceded by tetanus, or apoplexy, or mortal faintness. Nor is the violence of the poisoning proportional to the extent of the local injury: in fact, death is most rapid under circumstances in which the stomach is least injured, namely, when the acid is considerably diluted.[^[7]]

Let us now proceed to enquire, then, in what way the influence of a poison is conveyed from one organ to another.

Here it will at once be perceived that the conveyance can be accomplished in one of two ways only. Either the local impression passes along the nerves to the organ secondarily affected; or the poison enters the bibulous vessels, mingles with the blood, and passes through the medium of the circulation. In the former way poisons are said to act through sympathy, in the latter, through absorption.

1. On the Action of Poisons through Sympathy. In the infancy of toxicology all poisons were believed to act through sympathy. Since Magendie’s discoveries on venous absorption in 1809, the favourite doctrine has on the other hand been, that most, if not all, act through the medium of the blood. And a recent theory, combining both views, represents that, although many poisons do enter the blood, the operation even of these nevertheless consists of an impression made on the sentient extremities of the nerves of the blood-vessels and conveyed thence along their filaments to the brain or other organs.

The nerves certainly possess the power of conveying from one organ to another various impressions besides those of the external senses. This is shown by many familiar phenomena; and in reference to the present subject, is aptly illustrated by the remote or sympathetic effects of mere mechanical injury and natural disease of the stomach. Acute inflammation of the stomach generally proves fatal long before death can arise from digestion being stopped; and it is accompanied with constitutional symptoms, neither attributable to injury of that function, nor developed in so marked a degree during inflammation in other organs. These symptoms and the rapid death which succeeds them are vaguely imputed to the general system sympathizing with the affected part; but it is more probable that one organ only is thus, at least in the first instance, acted on sympathetically, namely, the heart. The effects of mechanical injuries are still more in point. Wounds of the stomach may prove fatal before inflammation can begin; rupture from over-distension may cause instant death; and in either case without material hemorrhage.

These observations being held in view, it is impossible to doubt, that some organs sympathize with certain impressions made on others at a distance; nor can we imagine any other mode of conveyance for these impressions except along the nerves. The question, then, comes to be what are the impressions that may be so transmitted?

The statements already made will prepare us to expect a sympathetic action in the case of poisons that manifestly injure the structure of the organ to which they are applied. In the instance of the pure corrosives its existence may be presumed from the identity of the phenomena of their remote action with those of natural disease or mechanical injury. It was stated above that the mineral acids when swallowed often prove fatal in a very short space of time; and here, as in mere injury from disease or violence, the symptoms are an imperceptible pulse, fainting, and mortal weakness. Remote organs therefore must be injured; and from the identity of the phenomena with those of idiopathic affections of the stomach, even if there were no other proof, it might be presumed that the primary impression is conveyed along the nerves. We are not restricted, however, to such an argument: The presumptive inference is turned to certainty by the effect of dilution on the activity of these poisons. Dilution materially lessens or even takes away altogether the remote action of the mineral acids. Now dilution facilitates, instead of impeding their absorption: consequently they do not act on remote organs through that channel. There is no other way left by which we can conceive them to act, except by conveyance of the local impression along the nerves.—As to the irritants that are not corrosive, it can hardly be doubted, since they inflame the stomach, that the usual remote effects of inflammation will ensue, namely, a sympathetic injury of distant organs.

But it remains to be considered, whether distant organs may sympathize also with the peculiar local impressions called nervous,—which are not accompanied by any visible derangement of structure. This variety of action by sympathy is the one which has chiefly engaged the attention of toxicologists; and it has been freely resorted to for explaining the effects of many poisons. Nevertheless its existence is doubtful.

The only important arguments in support of the sympathetic action of poisons are, that unequivocal instances exist of local nervous impressions being conveyed to a limited extent along the nerves,—and that the rapidity of the effects of some poisons is so great as to be incompatible with any other medium of action except the nervous system.

In the first place it is maintained, that a limited nervous transmission, that is, the conveyance of a local impression, purely functional in its nature, to parts at a short distance from the texture acted on directly, must occur in some instances,—as, for example, in the action of belladonna in dilating the pupil when applied to the conjunctiva of the eye, and in the effect of opium in allaying deep-seated pain when applied to the integuments over the affected part. It is by no means clear, however, that nervous transmission is in such circumstances the only possible medium of action; and that the phenomena may not as well be owing to the agent being conveyed in substance, by imbibition or absorption, to the parts ultimately acted on. It is not unworthy of remark too, that in the case of hydrocyanic acid,—a poison, which, more perhaps than any other, has been held to act by sympathy, and which produces on the integuments a direct local impression of a peculiar and unequivocal kind,—there is positive evidence of the direct impression not being conveyed along the nerves, even to the most limited distance; for I have not been able to observe the slightest effect beyond the abrupt line on the skin which defines the spot with which the acid had been in contact.

Secondly, it is thought that certain poisons, such as hydrocyanic acid, strychnia, alcohol, conia, and some others, produce their remote effects with a velocity, which is incompatible with any conceivable mode of action except the transmission of a primary local impulse along the nerves, and more especially incompatible with the poison having followed the circuitous route of the circulation to the organs which are affected by it remotely. Thus in regard to the hydrocyanic acid, Sir B. Brodie has stated,[^[8]] that a drop of the essential oil of bitter almonds, which owes its power to this acid, caused convulsions instantly when applied to the tongue of a cat; and that happening once to taste it himself, he had scarcely applied it to his tongue, when he felt a sudden momentary feebleness of his limbs, so that he could scarcely stand. Magendie,[^[9]] speaking of the pure hydrocyanic acid, compares it in point of swiftness of action to the cannon ball or thunderbolt. In the course of certain experiments made not long ago with the diluted acid by Dr. Freer, Mr. Macaulay and others,[^[10]] to decide the true rapidity of this poison, several dogs were brought under its influence in ten, eight, five, and even three seconds; during an experimental inquiry I afterwards undertook for the same purpose,[^[11]] I remarked on one occasion that a rabbit was killed outright in four seconds; and Mr. Taylor has more recently stated, that he has seen the effects induced so quickly in cats, that there was no sensible interval of time between the application of the poison to the tongue and the first signs of poisoning.[^[12]] Strychnia, the active principle of nux-vomica, acts sometimes with a speed little inferior to that of hydrocyanic acid; for Pelletier and Caventou have seen its effects begin in fifteen seconds.[^[13]] Alcohol, according to Sir B. Brodie,[^[14]] also acts on animals with equal celerity; for when he introduced it into the stomach of a rabbit, its effects began when the injection was hardly completed. Conia, the active principle of hemlock, is not less prompt in its operation: when it was injected in the form of muriate into the femoral vein of a dog, I was unable, with my watch in my hand, to observe an appreciable interval between the moment it was injected and that in which the animal died;[^[15]] certainly the interval did not exceed three or at most four seconds.

Facts such as these have been long held adequate to prove that some poisons must act on remote organs by sympathy or transmission of a local impulse along the nerves; and in the last edition of this work they were acknowledged to warrant such a conclusion. It was thought difficult to account for the phenomena on the supposition that the poison was conveyed in substance with the blood to the organ remotely affected by it; for it appeared impossible that, in so short a space of time as elapsed in some of the instances now referred to, the poison could enter the veins of the texture to which it was applied, pass into the right side of the heart, follow the circle of the pulmonary circulation into the left side of the heart, and thence be transmitted by the arterial system to the capillaries of the organ ultimately affected. But the progress of physiological discovery has lately brought the soundness of these views into question. Some years ago Dr. Hering of Stuttgardt showed that the round of the circulation may be accomplished by the blood much more speedily than had been conceived before; for the ferro-cyanide of potassium, injected into the jugular vein of a horse, was discovered by him throughout the venous system at large in the short space of twenty or thirty seconds, and consequently must have passed in that period throughout the whole double circle of the pulmonary and systemic circulation.[^[16]] This discovery at once shook the validity of many, though not all, of the facts which had been previously referred to the agency of nervous transmission on the ground of the celerity with which the effects of poisons are manifested. More recently an attempt has been made by Mr. Blake to prove, that the circulation is so rapid as to admit even of the swiftest cases of poisoning being referred to the agency of absorption. Mr. Blake, who is altogether opposed to the occurrence of nervous transmission in the instance of any poison, has found that ammonia, injected into the jugular vein of a dog, was indicated in its breath in four seconds; and that chloride of barium or nitrate of baryta, introduced into the same vessel, could be detected in the blood of the carotid artery in about sixteen seconds in the horse, in less than seven seconds in the dog, in six seconds in the fowl, and in four seconds in the rabbit.[^[17]] These interesting discoveries, however, will not absolutely destroy the conclusiveness of all the facts quoted above in support of the existence of a sympathetic action. For example they do not shake the validity of those observations, in which it appeared that an interval inappreciable, or barely appreciable, elapsed between the application and action of hydrocyanic acid and of conia. Mr. Blake indeed denies the accuracy of these observations, insisting that, in those he made himself with the most potent poisons, he never failed to witness, before the poison began to act, an interval considerably longer than what had been observed by others, and longer also than what he had found sufficient for the blood to complete the round of the circulation; that, for example, the wourali poison injected into the femoral or jugular vein did not begin to act for twenty seconds, conia and tobacco for fifteen seconds, and extract of nux vomica for twelve seconds; and that hydrocyanic acid dropped on the tongue did not act for eleven seconds if the animal was allowed to inhale its vapour, and not for sixteen seconds, if direct access to the lungs was prevented by making the animal breathe through a tube in the windpipe. But Mr. Blake cannot rid himself thus summarily of the positive facts which stand in his way. Duly weighed, the balance of testimony is in favour of those whose accuracy he impugns. For in the first place, they had not, like him, a theory to build up with their results, but were observing, most of them at least, the simple fact of the celerity of action. Then, their result is an affirmation or positive statement, and his merely a negative one: They may perfectly well have observed what he was not so fortunate as to witness. And lastly, it is not unreasonable to claim for Sir B. Brodie, Dr. Freer, Mr. Macaulay, and Mr. Taylor, all of them practitioners of experience, the faculty of noting time as accurately as Mr. Blake himself. As for my own observations, I feel confident they could not have been made more carefully, and that I had at the moment no preconceived views which the results upheld, but, if anything, rather the reverse.

It is impossible therefore to concede, that Mr. Blake’s inquiries, merely because they are at variance with prior results, apparently not less precise and exact than his own, put an end to the argument which has been drawn, in favour of the existence of a sympathetic action, from the extreme swiftness of the operation of some poisons. At the same time, on a dispassionate view of the whole investigation, it must be granted to be doubtful, whether this argument can be now appealed to in its present shape with the confidence which is desirable. And on the whole, the velocity of the circulation on the one hand, and the celerity of the action of certain poisons on the other, are both of them so very great, and the comparative observation of the time occupied by the two phenomena respectively becomes in consequence so difficult and precarious, that it seems unsafe to found upon such an inquiry a confident deduction on either side of so important a physiological question as the existence or non-existence of an action of poisons by sympathy.

In concluding these statements it is necessary to notice certain positive arguments which have been brought against the doctrine of nervous transmission.

It is alleged to be contrary to nature’s rule to adopt two ways of attaining the same end; and therefore, that, since many poisons undoubtedly act through absorption, it is unphilosophical to hold that others act by sympathy. There seems no sound reason, however, for thus imposing arbitrary limits on the functional powers conferred by nature on the organs of the animal body. And besides, the presumption thus derived is counterbalanced by the equally plausible supposition, that,—since nature has clearly established an action on remote organs through the medium of the nerves in the case of poisons which cause destruction or inflammation of the tissues to which they are applied,—the same medium of action may also exist in the instance of poisons which produce merely a peculiar nervous impression where they are applied.

But it is farther alleged, that poisons of the most energetic action have no effect, when they are applied to a part, the connection of which with the general system is maintained by nerves only. It is true that poisons seem to have no effect whatever when the circulation of the part to which they are applied has been arrested, or when every connecting tissue has been severed except the nerves. Thus Emmert found that the wourali poison does not act on an animal when introduced into a limb connected with the body by nerves alone.[^[18]] And I have ascertained that in the same circumstances no effect is produced on the dog by pure hydrocyanic acid dropped into the cellular tissue of the paw. But it cannot be inferred absolutely from these facts, that the wourali poison and hydrocyanic acid do not act through sympathy; because it has been urged that the integrity of the functions of the sentient extremities of the nerves, more especially their capability of receiving those nervous impressions which are held to be communicated backwards along their course, may be interrupted by arresting the circulation of the part. Still, as the function of sensation is maintained for some time in a severed limb connected with the trunk by nerves only, there is a probability, that all other functions of the nerves must be retained for a time also. And the presumption thus arising is strengthened by an imperfect experiment performed by Mr. Blake, which tends to show, although it does not absolutely prove, that a poison, introduced into the severed limb whose nervous connection with the trunk is entire, will not act, even if the blood be allowed to enter the limb by its artery and to escape from a wound in its vein, so that local circulation is in some measure maintained, without the blood returning to the trunk and general system.[^[19]]

On considering impartially all the facts that have been adduced in this inquiry, an impression must be felt that the doctrine of the sympathetic action of those poisons which produce merely a nervous local impression is insecurely founded. But an experimentum crucis is still wanted to decide the question.

2. Of the Action of Poisons through Absorption.—If doubts may be entertained whether poisons ever act by the transmission of local impulses, from the part to which they are applied, along the nerves to the organ upon which they act, no reasonable doubt can be entertained that many poisons act through the medium of absorption into the blood.

Poisons are believed to act through the blood for the following reasons. First, they disappear during life from the shut cavities or other situations into which they have been introduced; that is, they are absorbed. Several clear examples to this effect have been related by Dr. Coindet and myself in our paper on oxalic acid. In one experiment four ounces of a solution of oxalic acid were injected into the peritoneal sac of a cat, and killed it in fourteen minutes; yet, on opening the animal, although none of the fluid had escaped by the wound, we found scarcely a drachm remaining.[^[20]] In recent times Professor Orfila has proved that various poisons, such as arsenic, tartar-emetic, and acetate of lead, disappear in part or wholly from wounds into which they had been introduced.[^[21]] Next, many poisons act with unimpaired rapidity, when the nerves supplying the part to which they are applied have been previously divided, or even when the part is attached to the body by arteries and veins only. Dr. Monro, secundus, proved this in regard to opium;[^[22]] and the same fact has been since extended by Sir B. Brodie and Professor Emmert to wourali,[^[23]] by Magendie to nux vomica,[^[24]] by Coullon to hydrocyanic acid,[^[25]] by Charret to opium,[^[26]] and by Dr. Coindet and myself to diluted oxalic acid.[^[27]] Magendie’s experiment was the most precise of all: for, besides the communication with the poisoned part being kept up by a vein and an artery only, these vessels were also severed and reconnected by two quills. Farther, many poisons will not act when they are applied to a part of which the circulation has been arrested, even although all its other connections with the body have been left entire. This has been shown distinctly by Emmert in regard to the hydrocyanic acid; which, when introduced into the hind-leg of an animal after the abdominal aorta has been tied, produces no effect till the ligature be removed, but then acts with rapidity.[^[28]] An experiment of a similar nature performed by Mr. Blake with the wourali poison yielded the same result.[^[29]] Again, many poisons act with a force proportional to the absorbing power of the texture with which they are placed in contact. This is the criterion which has been commonly resorted to for discovering whether a poison acts through the medium of the blood. It is applicable, however, only when the poison acts sensibly in small doses; for those which act but in large doses cannot be applied in the same space of time over equal surfaces of different textures. The difference in the absorbing power of the different tissues has been well ascertained in respect to a few of them only. The most rapid channel of absorption is by a wound, or by immediate injection into a vein; the surface of the serous membranes is a less rapid medium, and the mucous membrane of the alimentary canal is still less rapid. Now it is proved of many poisons that, when applied in similar circumstances to these several parts or tissues, their activity is proportional to the order now laid down. Lastly, it has been proved of nux-vomica, that if the extract be thrust into the paw of an animal after a ligature has been tightened round the leg so as to stop the venous, but not the arterial circulation of the limb, blood drawn from an orifice in a vein between the wound and the ligature, and transfused into the vein of another animal, will excite in the latter the usual effects of the poison, so as even to cause death; while, on the contrary, the animal from which the blood has been taken will not be affected at all, if a sufficient quantity be withdrawn before the removal of the ligature. These interesting facts, which are capable of important practical applications, were ascertained by M. Vernière.[^[30]]

On weighing attentively the arguments here brought forward, it seems impossible to doubt, that some poisons are absorbed into the blood before they act, and that their entrance into the blood is not a mere fortuitous antecedent, but a condition essential to their action.

But it is farther held that poisons which act through absorption, do so by being conveyed in substance along with the blood to the part where their action is developed,—that their action eventually depends on the organ, whose functions are thrown into disorder, becoming impregnated with poisoned blood. Now, the arguments detailed above do not absolutely prove this conveyance and impregnation. They show that poisons enter the blood, and act somehow in consequence of entering it; but they do not prove in what manner the action subsequently takes place.

It was at one time indeed supposed that the same facts, which prove their admission into the blood, proved also their transmission in substance to the organs acted on by them. But Dr. Addison and Mr. Morgan have shown that this is not a legitimate conclusion, and that a different theoretical view may be taken of the facts,—namely, that the action may really take place by the poison producing on the sentient extremities of the nerves of the inner membrane of the blood-vessels a peculiar impression which is conveyed through the nerves to the part ultimately affected.[^[31]] They have endeavoured to found this theory upon evidence, that the poison is not carried beyond the venous system; or that, if conveyed farther, it is carried incidentally, and not for the purpose of impregnating the textures of the organ which suffers. The evidence they have brought forward on this head is chiefly the following. 1. Poisons which act on a particular organ at a distance do not act more quickly when introduced into the artery which supplies it, than when introduced into its vein, or even into the principal artery of a distant part of the body.[^[32]] 2. If a poison be introduced into a great vein with a provision for preventing its passage towards the heart, it will act with as great rapidity, as if no obstacle of the kind existed. Thus, if the jugular vein, secured by two temporary ligatures, be divided between them and reconnected by a tube containing wourali, the animal will not be affected more quickly on the removal of both ligatures, than on removing only the ligature farthest from the heart.[^[33]] 3. The arterial blood of a poisoned animal is incapable of affecting another animal. Thus, if the carotid artery and jugular vein of one dog be divided, and both ends of each reciprocally connected by tubes with the divided ends of the corresponding vessels of another dog, and extract of nux-vomica be introduced into a wound in the face of one of them,—the animal directly poisoned alone perishes, and the other remains unharmed to the last.[^[34]]

These are at first view strong arguments against the transmission of poisons with the blood to the organs remotely acted on; and the facts on which they are founded are on the other hand easily explained under the new theory advanced by the authors, that the medium of action is the nerves which supply the inner membrane of the blood-vessels. But their inquiries, however ingenious and plausible, have not stood the test of physiological scrutiny. Their first experimental fact has been contradicted by Mr. Blake; who has found that the wourali poison, which does not begin to act for twenty seconds when injected into a vein, will produce obvious effects in seven seconds only if injected into the aorta through the axillary artery.[^[35]] The second experiment, showing that poison confined in a vein will act although prevented by a ligature from reaching the heart, is held by the opponents of Dr. Addison and Mr. Morgan to be fallacious, in as much as the blood behind the ligature may be carried backwards till it meets with an anastomosing vein and is so carried by a collateral vessel to the heart. To the third experiment it may be objected, that there was, in the mode in which they conducted it, no satisfactory evidence that the reciprocal circulation was kept up by the carotid artery and jugular vein. And this will appear an important objection to every one practically acquainted with experiments of transfusion. For on the one hand it is exceedingly difficult, in such complicated experiments, to prevent coagulation of the blood in one vessel or another, before the connection of all the arteries and veins is established; and on the other, it may be urged, as Mr. Blake has done, that the pressure of the blood in the distal end of the carotid artery in the animal not directly poisoned may be equal, or even superior, to the pressure in the proximal end of the same vessel in the other animal,—so that the blood may not pass from the latter into the former, although it should continue fluid.

In opposition to the theory of Dr. Addison and Mr. Morgan, and in support of the doctrine, that poisons act by being carried in substance with the blood into the tissues of the remote organs on which they act, a variety of important experimental evidence has been brought forward since the publications of the Essay of these gentlemen. In the first place, the concurrent testimony of a great number of recent chemical inquirers establishes undeniably, that poisons absorbed into the veins of the part to which they are applied are to be detected throughout many of the tissues of distant organs. This fact will be enlarged on and illustrated presently. Secondly, on the authority of Mr. Blake, and in contradiction of the experiments of Dr. Addison and Mr. Morgan, it appears that, as already stated, poisons act more quickly when injected into the aorta than into the venous system; a fact which is easily understood, on considering that when injected into the aorta they reach their destination directly, whereas, if injected into a vein they must first arrive at the right side of the heart, and then be transmitted through the circle of the pulmonary circulation before reaching even the aorta. Thirdly, the relative rapidity with which poisons act on different animals follows the ratio of the velocity of the circulation in each. Thus, Mr. Blake found, that in the horse nitrate of baryta is conveyed by the circulation from the jugular vein to the carotid artery in sixteen seconds, and that strychnia injected into the jugular vein begins to act on the nervous system after exactly the same interval: That in the dog chloride of barium passes from the vein to the artery in seven seconds, and extract of nux-vomica begins to act as a poison in twelve seconds: That in the fowl the passage of the blood seems to take place in six seconds, and the nitrate of strychnia to act in six seconds and a half: And that in the rabbit the passage of the blood is effected in four seconds only, and the first signs of the action of strychnia occur in four seconds and a half.[^[36]]

On the whole, then, it may be considered as well established, that probably all, but certainly some, poisons,—of the kind whose topical action does not consist in causing destruction or inflammation of the textures to which they are applied,—produce their remote effects solely by entering the blood, and through its means impregnating the organs which are acted on at a distance. And farther, if this doctrine be admitted as established, it may also be allowed, that many poisons which do cause topically destruction or inflammation, and remotely the usual sympathetic effects of these changes of structure, also possess the power of affecting distant organs through the medium of the blood.

Of the discovery of Poisons in the Blood.—Such being the case, it becomes an object of paramount interest, with reference both to the practice of medical jurisprudence, to inquire whether poisons can be detected in the circulating fluids, or generally in parts of the body remote from the place where they are introduced.

A variety of circumstances long rendered it impossible to determine satisfactorily the question, whether poisons could be detected in the blood, the secretions, and the soft textures of the body. In the first place, we now know that the quantity of the more active poisons, which is required to occasion death, is so small, that, considering the crude methods of analysis formerly trusted to, and the obstacles opposed to the successful application of them by the presence of organic matter, there can be no wonder that chemists, even but a few years ago, could not satisfy themselves whether the objects they were in search of had been detected or not. Then, it was partly known before, and is now fully established, that various poisons are removed beyond the reach of analysis before death, in consequence of passing off with the secretions, particularly the urine. Farther, it seems probable that, of the poisons which act through absorption, several do not remain or at least do not accumulate, in the blood; and that they are not distributed with it throughout the textures indifferently, but are deposited, as absorption goes on, in particular organs, such as the liver,—which it was not much the practice to examine in former investigations. And lastly, some poisons are speedily decomposed on entering the blood: They either cause obvious changes in the constitution of the blood, and themselves undergo alteration likewise; or without the blood becoming appreciably different in its properties from the healthy state, the poison undergoes a rapid change in the molecular affinities of its elements, and so disappears. Of the former course of things distinct illustrations are furnished by nitric oxide gas and sulphuretted-hydrogen gas when injected into a vein in a living animal: of the latter an equally unequivocal example occurs in oxalic acid, which Dr. Coindet and I found to be undiscoverable in the blood of the vena cava of a dog killed in thirty seconds by the injection of eight grains and a half of it into the femoral vein.

But the improvements that have been lately made in the methods of analysis for the detection of poisons in a state of complex mixture with organic substances have done away with a great part of the obstacles which prevented a thorough inquiry as to the existence of poisons in the blood and textures of the body. Some important researches of this kind were referred to in the last edition of the present work; and since then many additional facts, of equal variety and precision, have been communicated by different observers, but especially by Professor Orfila. Under the head of each poison an account will be given hereafter of the evidence in support of the discovery of it by chemical analysis in the blood, textures, and excretions. In the present place it is sufficient to state in general terms that the evidence is quite satisfactory in the instances of iodine, sal-ammoniac, oxalic acid, nitre, sulphuret of potassium, arsenic, mercury, copper, antimony, tin, silver, zinc, bismuth, lead, hydrocyanic acid, cyanide of potassium, carbazotic acid, sulphuretted-hydrogen, camphor, and alcohol.

Of the Organs affected by the remote action of Poisons.—Having now taken a general view of the mode in which poisons act on distant parts, I shall next consider what organs are thus brought under their operation. Poisons have been often, but erroneously, said to affect remotely the general system. A few of them, such as arsenic and mercury, do indeed appear to affect very many organs of the body. But by much the larger proportion seem on the contrary to act on one or more organs only, not on the general system.

Of the poisons which act remotely through a sympathy of distant parts with an organic injury of the textures directly acted on, many appear to act sympathetically on the heart alone. Taking the mineral acids as the purest examples of poisons that act independently of absorption into the blood-vessels, it will be seen on inquiry that all the symptoms they produce, in addition to the direct effects of the local injury, are those of depressed action of the heart,—great feebleness, fainting, imperceptible pulse, cold extremities. Even the less prominent of the secondary symptoms are almost all referrible to a depressed state of the circulation. In particular, they are not necessarily, and indeed are seldom actually, blended with any material symptom of disorder in the brain; which certainly could not be the case if the general or whole system suffered.

With respect to that more numerous class, which act remotely either through the medium of the blood or by the transmission along the nerves of an undiscernible impression made on their sentient extremities, some certainly possess a very extended influence over the great organs of the body; but the greater number are much more limited in their sphere of action. Some act chiefly by enfeebling or paralyzing the heart, others principally by obstructing the pulmonary capillaries, others by obstructing the capillaries of the general system, others by stimulating or depressing the functions of the brain or of the spinal cord, others by irritating the alimentary canal, others by stimulating one or another of the glandular organs, such as the salivary glands, the liver, the kidneys, or the lymphatic glands.

Some poisons of this kind act chiefly, if not solely, on the heart. The best examples are infusion of tobacco, and upas antiar. Sir B. Brodie observed, that when the infusion of tobacco was injected into any part of the body, it speedily caused great faintness and sinking of the pulse; and on examining the body instantly after death, he found the heart distended and paralyzed, not excitable even by galvanism, and its aortal cavities filled not with black, but with florid blood, while the voluntary muscles were as irritable as after other kinds of death.[^[37]] The upas antiar he found to be similarly circumstanced.[^[38]] Arsenic and oxalic acid are also of this kind. In an animal killed by arsenic, and in which the gullet and voluntary muscles continued long contractile, Dr. Campbell found the heart immediately after death containing arterial blood in its aortal cavities, and insensible to galvanism.[^[39]] Dr. Coindet and I frequently witnessed the same facts in animals killed with oxalic acid: When the heart at the moment of death was completely palsied and deprived of irritability, we saw the intestines moving, and the voluntary muscles contracting long and vigorously from the mere contact of the air.[^[40]]

An interesting series of investigations has been lately made by Mr. Blake, relative to the influence of poisons on the heart, when they are directly introduced into the great veins. It does not absolutely follow that an action on the heart manifested in this way proves the occurrence of a similar action when the substance is admitted into the body through more ordinary channels, such as the stomach, intestines or cellular tissue. For on the one hand, some of the substances used by this physiologist cannot be admitted into the blood through ordinary channels in the quantity necessary for developing that action on the heart, which is excited when they are injected at once into the blood-vessels. And on the other hand, the results at which he thus arrives are not always in conformity with what have been obtained by prior observers, who resorted to the ordinary channels for introducing poisons into the body. It is possible, therefore, that Mr. Blake’s researches may not have the extensive bearings, which might at first sight appear, on the physiology of poisons and remedies. Nevertheless they are in themselves full of interest. They show that the salts of magnesia, zinc, copper, lime, strontia, baryta, lead, silver, ammonia, and potash, also oxalic acid, and digitalis, if injected into the jugular vein, produce a powerful and permanent depression of the heart’s action; which is evinced by the hæmadynamometer,[^[41]] indicating diminution of pressure in the great arteries, by the heart becoming motionless or nearly so before the breathing ceases, by its muscular structure presenting little or no irritability when stimulated immediately after death, and by the left cavities being found full of florid arterial blood.[^[41]]

Other poisons act on the lungs; but probably few, perhaps none, act on them alone. Magendie found that in poisoning with tartar-emetic the lungs are commonly inflamed and sometimes even hepatized.[^[42]] Mr. Smith and M. Orfila both remarked similar signs of pulmonary inflammation in animals poisoned with corrosive sublimate.[^[43]] But these poisons produce important effects on other organs likewise.

A set of novel and important facts setting forth the frequent operation of poisons on the lungs when they are admitted directly into the blood, has been recently brought to light by the researches of Mr. Blake. Many of the poisons mentioned above as acting powerfully on the heart were found by him not to exert any influence upon the lungs, such as oxalic acid and the salts of magnesia, lime, zinc, copper, ammonia, potash, and strychnia. Others, however, such as the salts of strontia, baryta, lead, and silver, as well as digitalis, all of which powerfully affect the heart, and, in addition to these, the salts of soda, which have no action at all on the heart, and hydrocyanic acid, tobacco, and euphorbium, which influence it feebly, or even dubiously,—produce, when injected into the jugular vein, obstruction of the capillaries of the pulmonary circulation, and consequently asphyxia. This is proved by the hæmadynamometer introduced into a vein indicating great increase of pressure in the venous circulation a few seconds after the introduction of the poison; by this instrument introduced into the femoral artery indicating great diminution of arterial pressure, although the heart continues to beat vigorously; by the breathing becoming at the same time laborious, without the heart suffering; by these symptoms preceding any signs of action on the nervous system; by the heart pulsating for some time after death; and in many instances by frothy mucus having accumulated in the air-passages, and congestion and extravasation having taken place in the lungs themselves.[^[44]]

A great number of the poisons whose action is remote, operate on the brain. The most decided proof of such an action is the nature of the symptoms; which are, giddiness, delirium, insensibility, convulsions, palsy, coma. Some physiologists have also sought for evidence in the body after death, and have imagined they found it in congestion of the vessels in the brain, and even extravasation of blood there; but it will be seen under the head of Narcotic Poisons that such appearances are far from being essential, and indeed are seldom witnessed. All narcotic poisons act on the brain, and most narcotico-acrids too; but very frequently other organs are affected at the same time, and in particular the spine and heart.

The influence of poisons on the brain seems to be sometimes induced, not immediately, but indirectly through the intervention of a more direct influence on the pulmonary circulation. Thus Mr. Blake appears to have succeeded in proving that the insensibility and tetanic convulsions which immediately precede death, when certain substances, such as the salts of soda, are injected into the veins, depend simply on the obstruction directly produced in the pulmonary circulation causing increased pressure in the systemic veins, and consequently upon the brain and nervous centre generally. For when the jugular vein was opened after the development of tetanic convulsions, and blood was allowed to flow out, the nervous symptoms ceased, and the animal continued for two hours sensible and without any return of convulsions, dying eventually of hemorrhage.[^[45]] But more generally the effect produced on the brain is direct and specific. Thus opium and its active principle morphia suspend the functions of external relation, which are peculiarly dependent on the brain; while for a long time the respiration and circulation are little affected. Even when the poison is admitted directly into the veins, the pulmonary capillaries are not obstructed, and the heart is only somewhat enfeebled in its contractions;[^[46]] and in ordinary cases of poisoning with these substances the heart continues to pulsate, and the lungs also discharge their office, long after sensibility is extinguished and voluntary motion arrested,—until at length the circulation and respiration become affected consecutively by the depressed state of the nervous system.

Some poisons act specifically on the spinal cord. Those which are best known to possess such an action are nux-vomica, the other species of plants which, like it, contain strychnia, and also conia and the wourali poison. The tribe of poisons of which nux-vomica may be taken as the type excite violent fits of tetanus, during the intervals of which the mind and external senses are quite entire; and death takes place during a paroxysm, apparently from suffocation caused by spasmodic fixing of the chest. Their action on the spine is quite independent of any action on the brain; if indeed such action exist at all. For when the spinal cord is separated from the brain by dividing the medulla oblongata, the effects on the muscles supplied by the spinal cord are produced as usual.[^[47]] Conia, the active principle of hemlock, according to my own researches, produces in the lower animals, howsoever introduced, gradually increasing paralysis, without insensibility or delirium, and without the circulation or respiration being for some time affected, till at length death takes place from stoppage of the breathing by palsy of the respiratory muscles; and after death the heart continues beating vigorously, the muscles contract when irritated, and arterialization of the blood in the lungs may be kept up long by maintaining artificial respiration. In this instance it would appear, that the first effect is arrestment of the functions of the spinal cord; that the paralysis does not depend upon a direct action on the muscles; and that neither the brain, heart, nor lungs can be influenced, except secondarily through the consequences of general muscular paralysis.[^[48]] Many poisons which act on the brain also act on the spinal cord.

Other poisons apparently possess the singular property of impeding or arresting the general capillary circulation, and produce their tangible effects more or less through the medium of this operation. Such at least are the inferences which seem to flow from the researches of Mr. Blake; who found that many substances, soon after they are injected backwards by the axillary artery into the aorta, produce increased pressure in the arterial system indicated by the hæmadynamometer during life, and frequently congestion of the membranous textures as observed after death. Some substances have no effect of this kind. Others act on the general capillaries in concurrence with a similar action on the capillaries of the pulmonary circulation, such as the salts of strontia, baryta, lead, silver, and soda, euphorbium, tobacco and digitalis. But a few, such as potash and ammonia, with their salts, seem to influence the capillaries of the general circulation only.[^[49]] These are important conclusions, if legitimate; but it cannot be denied, that the facts on which they are based must be very difficult to isolate and observe with accuracy and without bias.

The organs not immediately necessary to life may be likewise all acted on by poisons indirectly. On this subject details are not called for at present. It may be sufficient to remark that there is hardly a considerable organ in the body, except perhaps the spleen and pancreas, which is not acted on by one poison or another. Arsenic inflames the alimentary mucous membrane, mercury the salivary organs and mouth, cantharides the urinary organs, chromate of potass the conjunctiva of the eyes, manganese the liver; iodine acts on the lymphatic glands; lead on the muscles; and spurred rye causes gangrene of the limbs.

Some poisons, as was already mentioned, may act on one important organ only, every other being left undisturbed: thus nux-vomica in general acts only on the spine. But much more commonly they act on several organs at once; and the action of some of them is complicated in an extreme degree. I may instance oxalic acid and arsenic. Oxalic acid when swallowed irritates and inflames the stomach directly, and acts indirectly on the brain, the spine, and the heart. A large dose causes sudden death by paralyzing the heart; if the dose is somewhat less, the leading symptom is violent tetanic spasm, indicating an action on the spine, and death takes place during a paroxysm, the heart continuing to contract for some time after; if the dose is still less, the spasms, at first distinct, become by degrees fainter and fainter, while the sensibility in the intervals, at first unimpaired, becomes gradually clouded, till at length pure coma is formed without convulsions,—thus indicating an action on the brain. As for arsenic, coupling together the symptoms during life and the appearances in the dead body, it will be seen afterwards to have the power of acting on the brain, heart, and lungs,—the throat, gullet, stomach, and intestines,—the lining membrane of the nostrils and eyelids,—the kidneys, bladder, and vagina; and, what is remarkable, proofs of an action on all these parts may be witnessed in the course of a single case. The effects of mercury are hardly less multifarious.

Section II.—On the Causes which modify the Actions of Poisons.

By a variety of causes the action of poisons may be modified both in degree and in kind. The most important of them are—quantity; state of aggregation; state of chemical combination; mixture; difference in tissue; difference in organ; habit; idiosyncrasy; and lastly, certain states of disease.

1. Quantity affects their action materially. Not only do they produce their effects more rapidly in large doses; it is sometimes even quite altered in kind. A striking example has just been related in the case of oxalic acid; which, according to the dose, may corrode the stomach, or act on the heart, or on the spine, or on the brain. In like manner arsenic in a small dose may cause gastritis of several days’ duration; while a large dose may prove fatal in two or three hours by affecting the action of the heart. White hellebore in small doses excites inflammation in the stomach and bowels, in larger doses giddiness, convulsions, coma; and in either way it may prove fatal.

2. As to state of aggregation,—poisons act the more energetically the more minutely they are divided, and hence most energetically when in solution. Some which are very energetic in the fluid state, hardly act at all when undissolved. Morphia, the alkaloid of opium, may be given in powder to a dog without injury in a dose, which, if dissolved in oil or alcohol, would soon kill several. Previously dissolving poisons favours their action in two ways,—by diffusing them quickly over a large surface, and by fitting them for entering the bibulous vessels. Poisons, before being absorbed, must be dissolved; and hence, those which act though solid and insoluble in water, must, as a preliminary step, be dissolved by the animal fluids at the mouths of the vessels. In this way the poisonous effects of carbonate of baryta and arsenite of copper are explained; for though insoluble in water, they are soluble in the juices of the stomach.

Differences in aggregation, like differences in quantity, may affect the kind as well as the degree of action. Camphor in fragments commonly causes inflammation of the stomach; dissolved in spirit or olive oil, it causes delirium or tetanus and coma.

The reduction of certain poisons to the state of vapour serves the same end as dissolving them. When poisons are to be introduced by the skin, no previous operation is more effectual than that of converting them into vapour.

3. The next modifying cause is chemical combination. This is sometimes nothing more than a variety of the last. If a poison, in combining with another substance, acquire greater solubility, it also generally acquires greater activity, and vice versa: Morphia, itself almost inert, because insoluble, becomes active by uniting with acids, for they render it very soluble: Baryta as a very active poison, becomes quite inert by uniting with sulphuric acid, for the sulphate of baryta is altogether insoluble.

In regard to the influence of chemical combination two general laws may be laid down. One is, that poisons which only act locally, have their action much impaired or even neutralized, in their chemical combinations. Sulphuric acid and muriatic acid on the one hand, and the two fixed alkalis on the other, possess a violent local action; but if they are united so as to form sulphates or muriates, although still very soluble, they become merely gentle laxatives. But the case is altered if either of the combining poisons also act by entering the blood. For the second general law is, that the action of poisons which operate by entering the blood, although it may be somewhat lessened, cannot be destroyed or altered in their chemical combinations. Morphia acts like opium if dissolved in alcohol or fixed oil; if an acid be substituted as the solvent, a salt is formed which is endowed with the same properties: The sulphate, muriate, nitrate, acetate of morphia all act like opium. Strychnia, arsenic, hydrocyanic acid, oxalic acid, and many more come under the same denomination: Each produces its peculiar effects, with whatever substance it is combined, provided it do not become insoluble.

Mr. Blake has recently laid down what may be considered a branch or corollary of the second of these general propositions, and has confirmed it by many appropriate experimental facts,—namely, that the salts of the same base produce the same actions, independently of the acids with which they are combined.[^[50]] The law, however, is a more general one, as given above, and was stated in former editions of the present work. It applies not only to bases, but likewise to acids, such as the hydrocyanic, oxalic, arsenious, and arsenic acids, and also to neutral organic principles which act through the blood, such as picrotoxin, colocynthin, elaterin, and narcotin.

The same author considers it to be also a probable conclusion from a variety of experiments on the salts of various bases, that those salts which are isomorphous, or possess the same crystalline form, are closely allied in action.[^[51]]

4. The effect of mixture depends partly on the poisons being diluted. Dilution, by prolonging the time necessary for their being absorbed, commonly lessens their activity; yet not always; for if a poison which acts through the blood is also a powerful irritant, moderate dilution will enable it to enter the vessels more easily: a small dose of concentrated oxalic acid acts feebly as an irritant or corrosive; moderately diluted, it quickly enters the blood and causes speedy death.[^[52]] The effect of mixture may depend also in part on the mere mechanical impediment interposed between the poison and the animal membranes. This is particularly obvious when the mass containing the poison is solid or pulpy; for then the first portions of the poison that touch the membrane may cause an effort of the organ to discharge the rest beyond the sphere of action,—if, for example, it is the stomach,—by vomiting. The effect of mixture in interposing a mechanical impediment is also well illustrated where the substance mixed with the poison is a fine, insoluble powder, capable of enveloping its several particles. Thus it is that small, yet poisonous doses of arsenic may be swallowed and retained with impunity, if mixed with finely powdered charcoal, magnesia, and probably cinchona-bark, or the like. Besides diluting and mechanically obstructing their application, the admixture of other substances may alter the chemical nature of poisons, and so change their action.

It is important to keep in view, that the influence of mixture may be exerted in consequence of the cavity into which a poison is introduced being at the time filled with contents. Some of the most powerful and unerring poisons may in such circumstances altogether fail to produce their usual effect, if speedily vomited. Thus Wibmer notices the case of a man, who swallowed an ounce and a half of arsenic after a very hearty meal, had merely a severe attack of vomiting with subsequent colic, and got quite well in four days.[^[53]] And a still more pointed instance has been briefly mentioned by Dr. Booth of Birmingham, where an ounce of corrosive sublimate was swallowed after a full meal without any material ill consequence, vomiting having been speedily induced.[^[54]]

5. Difference of tissue is an interesting modifying power in a physiological point of view, but does not bear so directly on medico-legal practice as the rest, and may therefore be passed over cursorily.

On the corrosives and irritants a difference of tissue acts but indirectly: their effects vary not so much with the tissue as with the organ of which it forms part. But as to poisons which act through the blood, their energy must evidently depend on the activity of absorption in each texture.

The cutaneous absorption is slow, on account of the obstacle presented by the cuticle, and by the intricate capillaries of the true skin. Accordingly many active poisons are quite inert when applied to the unbroken skin, or even to the skin deprived of the cuticle. Hydrocyanic acid, perhaps the most subtle of all poisons, was found by Coullon to have no effect when dropped on the skin of a dog.[^[55]] Some authors have even gone so far as to deny that poisons can be absorbed at all through the skin, unless they are pressed by friction through the cuticle. But this is an error; most gaseous poisons, such as carbonic acid and sulphuretted hydrogen, and some solid poisons when volatilized, such as the vapours of cinnabar, will act though simply placed in contact with the skin; and there is distinct evidence that corrosive sublimate will bring on mercurial action in the form of a warm bath, or when used as a liniment.

On the mucous membrane of the stomach and intestines, poisons act much more energetically than on the skin; which clearly depends in a great measure on the superior rapidity of absorption there,—or, according to some, on the facility with which poisons come in contact with the sentient extremities of nerves.

The serous membranes possess an activity of absorption which hardly any other unbroken texture can equal. Accordingly many poisons act much more rapidly through the peritonæum than through the stomach. When oxalic acid is introduced under the same collateral circumstances into the stomach of one dog and the peritonæum of another, the dose may be so apportioned, that the same quantity, which does not prove fatal to the former, kills the latter in fourteen minutes.[^[56]]

While the preceding modes in which poisons enter the blood are indirect, they may be introduced directly by a wound in the vein. There is no way in which poisons, that act through the blood, prove more rapidly fatal. Some which act very slowly through the stomach cause instant death when injected into a vein. A peculiar variety of this mode of introducing poisons deserves to be distinguished, namely, the application of them to a wound. If the surface bleeds freely, they may not act at all, because they are washed away. But if they adhere, they soon enter the divided veins. Hence, if they act in small doses, this mode of applying them is hardly less direct than if they were at once injected into a vein.

So far the effect of difference in tissue has been determined. Poisons that act through the blood act least energetically on the skin, more actively on the alimentary mucous membrane, still more so on serous membranes, and most powerfully of all when introduced directly into a vessel. There are other textures, however, which merit notice, although their place in the scale of activity has not been exactly settled.

On the mucous membrane of the pulmonary air-cells and tubes, poisons act with a rapidity which is scarcely surpassed by their direct introduction into a vein. This is plainly owing to the exceeding delicacy and wide surface of the membrane. Hence three or four inspirations of carbonic oxide gas will cause instant coma. A single inspiration of the noxious gas of privies has caused instant extinction of sense and motion. Nay, liquid poisons have been known to act through the same channel with almost equal swiftness. For M. Ségalas found that a solution of extract of nux-vomica caused death in a few seconds when injected in sufficient quantity into the windpipe; and that half a grain will thus kill a dog in two minutes, while two grains will rarely prove fatal when injected into the stomach, peritonæum, or chest.[^[57]]

As to the nervous tissue, it is a fact worthy of mention, that the poisons which appear to act on the sentient extremities of the nerves, do not act at all on the cut surface of the brain and nerves, or upon any part of the course of the latter. This has been proved with respect to most active narcotics.

The power of the cellular tissue as a medium of absorption, has not been, and cannot easily be, ascertained. On the one hand it is difficult to apply poisons to it, without also applying them to the mouths of divided vessels; and, on the other hand, it is difficult to make a set of experiments for comparison with others on the stomach, pleura, or peritonæum, as the cellular tissue does not form an expanded cavity, and consequently, the extent of surface to which a poison is applied cannot be made the same in each experiment of a series. It is a ready medium, however, for admitting poisons into the blood, especially if an artificial cavity be made where the tissue is loose, as, for example, by separating the skin from the muscles of the back with the finger introduced through a small incision in the integuments.

The variations caused by difference of tissue in the activity of poisons have been viewed in the previous remarks as depending chiefly on the relative quickness with which absorption goes on. But in this way it is impossible to explain the whole amount of the differences sometimes observed. Some poisons cause death when applied to a wound in the minutest quantity, but are quite harmless when swallowed in large doses: Others are diminished a little in activity, but still remain powerful and fatal poisons. There is not much difference in the power of arsenic when it is applied to different textures, the skin excepted. But oxalic acid injected into the peritonæum will act eight or ten times more rapidly than when swallowed and the poison of the viper may prove fatal to a man through a wound in almost invisible doses, while the whole poison of six vipers may be swallowed by so small a creature as a blackbird, with complete impunity.[^[58]] Differences in the absorbing power of the tissues cannot explain these facts.

The only rational way of accounting for them is by supposing that a part of the poison is decomposed,—the change being greatest where absorption is slowest and the power of assimilation strongest, namely, in the stomach,—and least where absorption is quickest and assimilation almost wanting, namely, in a wound. This explanation derives support from the different effects of change of tissue on poisons of the different kingdoms. Mineral poisons are least, and animal poisons are most, affected in their action by differences of tissue, while vegetable poisons hold the middle place:—an arrangement which coincides with the respective difficulty of decomposition among mineral, vegetable, and animal substances generally, whether under physical or under vital processes.[^[59]]

6. With respect to differences arising from difference of organ, these will, of course, be partly attributable to differences in tissue, but not altogether. For example, in the case of the pure corrosives or irritants, the injury caused will depend for its danger on the importance of the organ to the general economy of the body: Inflammation caused by a local poison in the stomach will be more quickly fatal than that excited in the intestines only; and such a poison may act violently on the external parts without materially impairing the general health.

7. Habit and Idiosyncrasy.—The remarks to be made under the present head are important in a medico-legal point of view: for they show how one man may be poisoned by a substance generally harmless, and another not harmed by a substance usually poisonous.

The tendency of idiosyncrasy is generally to increase the activity of poisons, or even to render some substances deleterious which are commonly harmless.

The effect of opium in medicinal doses is commonly pleasant and salutary; but in some individuals it produces disagreeable and even dangerous effects. Calomel, which in moderate doses is for the most part a mild laxative or sialagogue, will cause in some people, even in the dose of a few grains, violent salivation, ulceration of the mouth, nay, fatal gangrene. On the other hand, a few substances, which to most people are actively poisonous, have on some individuals comparatively little effect. There are extremely few poisons, however, in regard to which this kind of idiosyncrasy is well established and prominent. Mercury and alcohol are examples. The compounds of mercury, which in moderate quantity are mildly laxative or sialagogue to most people, but to some persons dangerously poisonous in very small doses, would, on the contrary, appear in other constitutions to be extremely inactive; for it has occasionally been found impossible to bring on the peculiar constitutional action of mercury by continuing the use of its preparations for months together. In general children are not easily affected by calomel as a sialagogue, but easily by its laxative action. As to alcohol, it is a familiar fact, that independently of the effects of habit, there are some constitutions which cannot be brought under the influence of intoxicating liquors without an extraordinary quantity of them and a long-continued debauch, while others are overpowered in a short space of time, and by very moderate excess; and there is no reason to doubt that very great constitutional differences also prevail in regard to the operation of a single large dose. A rarer idiosyncrasy is unusual insensibility to the action of opium. I am acquainted with a gentleman unaccustomed to the use of opium who has taken without injury nearly an ounce of good laudanum,—a dose which would certainly prove fatal to most people.

But not only does idiosyncrasy modify the action of poisons: Through its means, too, some substances are actually poisonous to certain individuals, which to mankind in general are unhurtful, nay, even nutritive.

With some people all kinds of red fish, trout, salmon, and even the richer white fish, herring, mackerel, turbot, or holibut, disagree as it is called—that is, act after the manner of poisons: They produce fainting, sickness, pain of the stomach; and if they were not speedily evacuated by vomiting, dangerous consequences might ensue. The same is often the case with mushrooms. The esculent mushrooms act on some people nearly in the same way as the poisonous varieties. Bitter almonds and other vegetable substances that contain hydrocyanic acid, sometimes produce stupor or nettle-rash in the small quantities used for seasoning food. In like manner many flowers, which to most persons are agreeable and not injurious, cannot be kept in the same room with some people on account of the severe nervous affections that are developed.

This idiosyncrasy may even be acquired. One of my relations, who was for many years violently affected by very small quantities of the richer kinds of fish, used at a previous period to eat them, and can now again do so, with impunity. Many people have acquired a similar idiosyncrasy with respect to eggs; instances of the same kind will be afterwards mentioned in respect to shell-fish, particularly muscles; indeed there are probably few articles of food in regard to which such idiosyncrasies may not in a few rare instances be met with, if we except the grains and common kinds of butcher-meat. I may add, that from facts which have come under my notice, I have sometimes suspected that a similar idiosyncrasy may be acquired in a slight degree, and for a short time only, in regard even to some kinds of butcher-meat, especially the flesh of young animals and pork. On this subject some illustrations will be found at the close of the chapter on diseased and decayed animal matter.

It does not appear well ascertained, that the effect of idiosyncrasy is ever to impair materially the energy of poisons, except in the instances of mercury, alcohol, and opium.

On the contrary, the tendency of habit when it does affect their energy, is, with a few exceptions, to lessen it. By the force of habit a person may take without immediate harm such enormous quantities of some poisons as would infallibly kill an unpractised person or himself when he began. There have been opium-eaters in this country who took for days together ten or even seventeen ounces of laudanum daily.

The influence of habit has been ascertained precisely in the case of a few common poisons only. On the whole, it would appear that more change is effected by habit in the action of the organic than in that of the inorganic poisons; and that of the former, those which act on the brain and nervous system, and produce narcotism, are altered in the most eminent degree. The best examples of the influence of habit are opium and vinous spirits. The action of such poisons is not always, however, entirely thrown away; they still produce some immediate effect; and farther, by being frequently taken, they may slowly bring on certain disease, or engender a predisposition to disease. A very singular exception to this rule prevails in the instance of tobacco; which, under the influence of habit, may be smoked daily to a considerable amount, and, so far as yet appears, without any cumulative effect on the constitution, like that of opium-eating or drinking spirits.

The inorganic poisons are most of them little impaired in activity by the force of habit. The pure irritants, indeed, do lose a little of their energy: for it seems that persons have acquired the power of swallowing with impunity considerable doses of the mineral acids. But as to inorganic poisons that enter the blood, habit certainly does not diminish, probably rather increases, their power. There is no satisfactory evidence, that a person by taking gradually-increasing doses of arsenic may acquire the power of enduring a considerably larger dose than when he began: On the contrary, the stomach rather becomes more tender to the subsequent dose by each repetition. I have little hesitation in avowing my disbelief of the alleged cases of arsenic-eaters and corrosive-sublimate-eaters, who could swallow whole drachms at once with impunity. Some have expressed surprise at this statement having been made in former editions of the present work, when there is such authority as Byron, Pouqueville, &c., for the hackneyed story of Soleyman, the sublimate-eater of Constantinople, who lived to the age of a hundred, eating a drachm of corrosive sublimate daily. I must avow, however, that such reporters of a feat so very extraordinary, and where deception was so highly probable, are to me no authority at all.

In the relative influence of habit on poisons of the three kingdoms of nature, a new argument will be discovered for the opinion given above respecting the partial decomposition of organic poisons in some of the tissues. In fact this partial decomposition accounts very well for the effect of habit: The effect of habit is probably nothing more than an increased power acquired by the stomach of decomposing the poison,—just as it gradually acquires an increased facility in digesting some alimentary substances which are at first very indigestible.

8. The last modifying cause to be mentioned comprehends certain diseased states of the body. The effect of disease, like that of habit, is in general to impair the activity of poisons. But it is only in the instance of a few diseases that this diminution is so strongly marked as to be important in relation to medical jurisprudence.—In the continued fever of this country there is a diminished susceptibility of the constitutional action of mercury; and this peculiarity is very strongly marked in the yellow fever, as well as in the bilious fevers generally of tropical climates. In some varieties of typhoid fever there is obviously a diminished sensibility to the action of wine and other spirituous liquors; but this diminution in a great majority of cases is much inferior to what some physicians have represented.—In severe dysentery the susceptibility of the narcotic action of opium is so much impaired, that a person unaccustomed to the use of that drug, may continue to take daily, for several days together, a quantity which might prove fatal to him in a state of health. In the severe form which dysentery occasionally puts on in this country I have known a patient take from twenty-four to thirty grains of opium daily, and retain it all, without experiencing more than a mild narcotic action.—In epidemic cholera the same insensibility has been remarked to the operation of opium.—It also occurs in the instance of excessive hemorrhagy.—According to the doctrines and practice of the present dominant school in Italy, there is an unusual insensibility during inflammatory dropsy to the irritant action of gamboge, so that sixty or eighty grains may be taken without harm.—There is no disease, however, in which the power of mitigating the action of poisons is more remarkably exhibited, than in tetanus: It is often scarcely possible to bring on the narcotic action of opium by any doses which can be administered; calomel, too, acts with much less energy than usual; and even common purgatives must be administered in doses considerably larger than those required in most other disorders.—Mania is similarly circumstanced: almost all remedies must be given in increased doses, narcotic remedies in particular. But there is good reason for believing that the impaired susceptibility of the action of poisons remarked in this disorder is far from being always so great as some have alleged.—Another disease allied to the last, where the diminution of susceptibility is often great, is delirium tremens. It has in particular been often found, that to produce sleep in this disease opium must be given in frequent large doses,—so large indeed, that they would undoubtedly prove fatal to a person in health. At the same time it is worthy of remark, that in some cases of delirium tremens, even violent in degree, the peculiarity now specified, as I have myself several times witnessed, is far from being strongly marked.—Hydrophobia always, and hysteria sometimes, impair the activity of poisons. I have seen cases of hysteria, more particularly those assuming the form of tetanus, where very large doses of opium were required to produce a calmative effect and sleep; and in hydrophobia it is well shown that the narcotic action of opium is not produced even by large doses often repeated.—The same state occurs in excessive hemorrhage.

In the operation of this class of modifying agents it is a general law, to which there are probably few exceptions, that they chiefly affect poisons of the organic kingdoms, and the narcotics above all. At least in the instance of most mineral poisons their influence is very inferior. Their operation may be accounted for in various ways. Sometimes, as in dysentery and cholera, the poison is carried with unusual rapidity through the alimentary canal. Sometimes again it remains comparatively inert, because on account of the impaired activity of absorption, it is not taken up with the usual quickness by the absorbent vessels. And sometimes, as in the instance of tetanus, mania, and rabies, the nervous system is in a state of peculiar excitement, by which the customary action of the poison is in a great measure, if not entirely, counteracted.

In a few diseased states of the system there is an increased susceptibility of the action of poisons: and it is important that the medical jurist should attend to this circumstance. When a poison has a tendency to bring on a peculiar pathological state of the system, or of a particular organ, which state is also produced by a disease existing at the time or impending, violent and even fatal consequences may ensue from doses of poisons which in ordinary circumstances are innocuous or beneficial. Thus in persons affected with apoplexy an ordinary dose of opium may accelerate death; and in people even with a mere tendency to apoplexy, if it is strongly marked, or appears from what are called warning symptoms to be on the point of developing itself, a common dose of such narcotics as occasion determination to the brain may excite the apoplectic attack. Thus, too, in cases of inflammatory disorders of the alimentary canal, irritating substances, in doses not otherwise injurious, may produce dangerous impressions on the tender membrane with which they come in contact. But in respect to this last example, it must be remarked, that the improvements or the caprice of medical practice have gone directly in face of the rule, by suggesting that some internal inflammations of the alimentary canal may be successfully treated with irritating remedies.

I might here perhaps have added among the causes which modify the action of poisons, sleep, and the administration of other poisons. The latter subject, however, will be better considered at the end of the Individual Poisons, under the title of Compound Poisoning. The former agent is of doubtful effect. Some observations on its influence will be found in the chapter on the Evidence of General Poisoning, p. [41].

Application of the preceding remarks to the Treatment of Poisoning. As an appendix to what has been said respecting the physiological action of poisons, and the causes by which it is liable to be modified, I shall here state shortly certain applications to the treatment of poisoning.

In the instance of internal poisoning, the great object of the physician is to administer an antidote or counter-poison. Antidotes are of two kinds. One kind takes away the deleterious qualities of the poison before it comes within its sphere of action, by altering its chemical nature. The other controls the poisonous action after it has begun, by exciting a contrary action in the system. In the early ages of medicine almost all antidotes were believed to be of the latter description, but in fact very few antidotes of the kind are known.

Chemical antidotes operate in several ways, according to the mode of action of the poison for which they are given. If the poison is a pure corrosive, such as a mineral acid, it will be sufficient that the antidote destroy its corrosive quality: Thus the addition of an alkali or earth will neutralize sulphuric acid, and destroy or at least prodigiously lessen its poisonous properties. In applying this rule care must be taken to choose an antidote which is either inert in itself, or, if poisonous, is, like the poison for which it is given, a pure corrosive or local irritant, and one whose properties are reciprocally neutralized.

If the poison, on the other hand, besides possessing a local action, likewise acts remotely through absorption, or by an impression on the inner coat of the vessels, mere neutralization of its chemical properties is not sufficient; for we have seen above that such poisons act throughout all their chemical combinations which are soluble. Here, therefore, it is necessary that the chemical antidote render the poison insoluble or nearly so; and insoluble not only in water, but likewise in the animal fluids, more particularly the juices of the stomach. The same quality is desirable even in the antidotes for the pure corrosives; for it often happens that in their soluble combinations these substances retain some irritating, though not any corrosive power. When we try by the foregoing criterions many of the antidotes which have been proposed for various poisons, they will be found defective; and precise experiments have in recent times actually proved them to be so.

The other kind of antidote operates not by altering the form of the poison, but by exciting in the system an action contrary to that established by the poison. On considering attentively, however, the phenomena of the action of individual poisons, it will be found exceedingly difficult to say what is the essence of a contrary action, and still more how that counter-action is to be brought about. Accordingly, few antidotes of the kind are known. Physiology or experience has not yet brought to light any mode of inducing an action counter to that caused by arsenic and most of the irritant class of poisons. It appears probable that the remote operation of lead may be sometimes corrected by mercury given to salivation, and that the violent salivation caused by mercury may be occasionally corrected by nauseating doses of antimony. But these are the only instances which occur to me at present of antidotes for irritant poisoning which operate by counter-action, unless we choose to designate by the name of antidote the conjunction of remedial means which constitute the antiphlogistic method of cure. In the class of narcotics we are acquainted with equally few constitutional antidotes, although the nature of the action of these poisons seems better to admit of them. Ammonia is to a certain extent an antidote for hydrocyanic acid, but by no means so powerful as some persons believe; and I am not sure that in this class of poisons we can with any propriety mention another antidote of the constitutional kind.

On the whole, then, it is chiefly among the changes induced by chemical affinities that the practitioner must look for counter-poisons; and the ingenuity of the toxicologists has thence supplied the materia medica with many of singular efficacy. When given in time, magnesia or chalk is an antidote for the mineral acids and oxalic acid, albumen for corrosive sublimate and verdigris, bark for tartar-emetic, common salt for lunar caustic, sulphate of soda or magnesia for sugar of lead and muriate of baryta, chloride of lime or soda for liver of sulphur, vinegar or oil for the fixed alkalis; and these substances act either by neutralizing the corrosive power of the poison, or by forming with it an insoluble compound.

In recent times a new object in the treatment of poisoning has been pointed out by the discoveries made in its physiology. As it has been proved that many of the most deadly poisons enter the blood, and in all probability act by circulating with that fluid, so it has been inferred that an important object in the treatment is to promote their discharge by the natural secretions. In support of this reasonable inference it has been lately rendered probable by Orfila, as will be seen under the head of the treatment of the effects of arsenic, that it is of great advantage in some forms of poisoning to increase the discharge of urine.

In the instance of external poisoning the main object of the treatment is to prevent the poison from entering the blood, or to remove it from the local vessels which it has entered.

One mode, which has been known to the profession from early times, and after being long in disuse was lately revived by Sir D. Barry, and applied with success to man, is the application of cupping-glasses to the part where the poison has been introduced.[^[60]] This method may act in various ways. It certainly prevents the farther absorption of the poison by suspending for a time the absorbing power of the vessels of the part covered by the cup. It also sucks the blood out of the wound, and may consequently wash the poison away with it. Possibly it likewise compresses the nerves around, and prevents the impression made by the poison on their sentient extremities from being transmitted along their filaments.

Another mode is by the application of a ligature between the injured part and the trunk, so as to check the circulation. This is a very ancient practice in the case of poisoned wounds, and is known even to savages. But as usually practised it is only a temporary cure: As soon as the ligature is removed the effects of the poison begin. It may be employed, however, for many kinds of poisoning through wounds, so as to effect a radical cure. We have seen that most poisons of the organic kingdom are in no long time either thrown off by the system or decomposed in the blood. Hence if the quantity given has not been too large, recovery will take place. Now, by means of a ligature, which is removed for a short time at moderately distant intervals, a poison, which has been introduced into a wound beyond the reach of extraction, may be gradually admitted into the system in successive quantities, each too small to cause death or serious mischief, and be thus in the end entirely removed and destroyed. Such is a practical application which may be made of some ingenious experiments performed not long ago by M. Bouillaud with strychnia, the poisonous principle of nux-vomica.[^[61]]

The last mode to be mentioned is by a combination of the ligature with venesection, deduced by M. Vernière from his experimental researches formerly noticed (p. [19]). Suppose a fatal dose of extract of nux-vomica has been thrust into the paw of a dog; M. Vernière applies a tight ligature round the limb, next injects slowly as much warm water into the jugular vein as the animal can safely bear, and then slackens the ligature. The state of venous plethora thus induced completely suspends absorption. The ligature is next tied so as to compress the veins without compressing the arteries of the limb, and a vein is opened between the wound and the ligature in such a situation, that the blood which flows out must previously pass through, or at least near the poisoned wound. When a moderate quantity has been withdrawn, the ligature may be removed with safety; and the extraction of the poison may be farther proved by the blood that has been drawn being injected into the veins of another animal; for rapid death by tetanus will be the result.[^[62]] It is not improbable that in this plan the preliminary production of venous plethora may be dispensed with; and then the treatment may be easily and safely applied to the human subject.

CHAPTER II.
ON THE EVIDENCE OF GENERAL POISONING.

This subject is purely medico-legal. It comprehends an account of the various kinds of evidence by which the medical jurist is enabled to pronounce whether poisoning in a general sense (that is, without reference to a particular poison), is impossible, improbable, possible, probable, or certain. It likewise comprises an appreciation of the circumstances which usually lead the unprofessional, as well as the professional, to infer correctly or erroneously a suspicion of such poisoning.

Under the present head might likewise be included the history of poisoning, the art of secret poisoning, and some other topics of the like kind. But the want of proper documents, and the unmeasured credulity which has prevailed on the subject of poisoning throughout all ages down to very recent times, has entangled these subjects in so intricate a maze of fable, that a notice of them, sufficiently detailed to interest the reader, would be quite misplaced in this work.

On the art of secret poisoning, however, as having been once an important object of medical jurisprudence, it might be expected that some comments should here be offered. But really I do not see any good reason for wading through the mass of credulous conjectures and questionable facts, which have been collected on the subject, and which have been copied into one modern work after another, for no other cause than that they are of classic origin, or feed our appetite for the mysterious. No one now seriously believes that Henry the Sixth was killed by a pair of poisoned gloves, or Pope Clement the Seventh by a poisoned torch carried before him in a procession, or Hercules by a poisoned robe, or that the operation of poisons can be so predetermined as to commence or prove fatal on a fixed day, and after the lapse of a definite and remote interval. With regard to the noted instances of secret poisoning, which occurred towards the close of the seventeenth century in Italy and France, it is plain to every modern toxicologist, from the only certain knowledge handed down to us of these events, that the actors in them owed their success rather to the ignorance of the age, than to their own dexterity. And as to the refined secrets believed to have been possessed by them, it is sufficient here to say, that although we are now acquainted with ten times as many and ten times as subtle poisons as were known in those days, yet none exist which are endowed with the hidden qualities once so universally dreaded.

The crime of poisoning, from its nature, must always be a secret one. But little apprehension need be entertained of the art of secret poisoning as understood by Toffana or Brinvilliers,[^[63]] or as it might be improved by a modern imitator. It seems to have escaped the attention of those who have written on the subject, that the practice of such an art requires the knowledge not only of a dexterous toxicologist, but also of a skilful physician; for success must depend on the exact imitation of some natural disease. It is only among medical men, therefore, and among the higher orders of them, that a Saint-Croix can arise now-a days. How little is to be dreaded on that head is apparent from the domestic history of the European kingdoms for the last half century, compared with their history some centuries ago. Few medical men have even been suspected, and those few only upon visionary grounds, and under the impulse of violent political feeling.[^[64]] In one late instance only, so far as I am aware, has it been proved that the physician’s art was actually prostituted to so fearful a purpose; and the detection of the crime in that case shows how difficult concealment will always be wherever justice is administered rigorously, and medico-legal investigations skilfully conducted.[^[65]]

Two extraordinary incidents which happened lately in Germany may appear at first sight at variance with these views. I allude to the cases of Anna Margaretha Zwanziger and Margaretha Gottfried, which justly excited much interest where they occurred, and are notorious to continental toxicologists. Zwanziger, while serving as housekeeper in various families in the territory of Bayreuth in Bavaria during the years 1808 and 1809, contrived to administer poison,—sometimes under the instigation of mere revenge or spite, sometimes for the purpose of clearing the way for her schemes of marriage with her masters,—to no fewer than seventeen individuals in the course of nine months; and of these three died.[^[66]] Gottfried, a woman in affluent circumstances and tolerable station in the town of Bremen, was even more successful. For she pursued her criminal career undiscovered for fifteen years; and when detected in 1828 had murdered actually fourteen persons, and administered poison unsuccessfully to several others. Her motive, as in the case of Zwanziger, was the mere gratification of a malevolent temper, or the removal of supposed obstacles to her matrimonial dreams. In neither of these instances, however, did the criminal possess any particular skill, or observe much measure in her proceedings. The cases of poisoning were of the common kind,—produced by arsenic,—proving in general quickly fatal,—and presenting the ordinary phenomena. I cannot help thinking, therefore, that the events now alluded to prove rather the ineffectiveness of the police where they happened, than the adroitness of the actors by whom they were brought about; and that they constitute no sound objection to the statement, that the art of secret poisoning is now unknown, and is not likely to be again revived.

It must be granted, indeed, that the late discoveries in chemistry and toxicology have made poisons known which might be employed in such a way as to render suspicion unlikely, and to baffle inquiry. But the methods now alluded to are hitherto very little known; they cannot easily be attempted on account of the rarity and difficult preparation of the poisons; they can never be practised except by a person conversant with the minute phenomena of natural disease; and it is no part of the object of this work to make them public.

The evidence, by which the medical jurist is enabled to pronounce on the existence or non-existence of poisoning in general, and to determine the subordinate questions that relate to it, is derived from five sources,—1, the symptoms during life; 2, the appearances in the dead body; 3, the chemical analysis; 4, experiments and observations on animals; and 5, certain moral circumstances, which are either inseparably interwoven with the medical proof, or cannot be accurately appreciated without medical knowledge.

Section I.—Of the Evidence from Symptoms.

Not many years ago it was the custom to decide questions of poisoning from the symptoms only. Till the close of last century, indeed, no other evidence was accounted so infallible: and for the simple reason, that in reality the other branches of evidence were even more imperfectly understood. So lately as 1763, and even in Germany, the solemn opinions of whole colleges were sometimes grounded almost exclusively on the symptoms.[^[67]] About that time, however, doubts began to be entertained of the infallibility of such evidence; these doubts have since assumed gradually a more substantial form; and it is now laid down by every esteemed author in Medical Jurisprudence, that the symptoms, however exquisitely developed, can never justify an opinion in favour of more than high probability.[^[68]] In laying down this doctrine medical jurists appear to me to have injudiciously confounded together actual symptoms with their general characteristics. If the doctrine is to be held as applying to the evidence from symptoms, only so far as they are viewed in questions of general poisoning,—that is, as applying to the general characters merely of the symptoms,—it is deduced from accurate principles. But if it is likewise to be applied, as recent authors have done, to the actual symptoms produced by particular poisons, and in all cases whatever of their action, then it is a rule clearly liable to several important exceptions. These exceptions will be noticed under the heads of the mineral acids, oxalic acid, arsenic, corrosive sublimate, nux vomica, &c. At present it is only the general characters of the symptoms, and the points in which they differ from the general characters of the symptoms of natural disease, that I propose to consider.

The chief characteristics usually ascribed to the symptoms of poisoning considered generally, are, that they commence suddenly and prove rapidly fatal,—that they increase steadily,—that they are uniform in nature throughout their course,—that they begin soon after a meal,—and that they appear while the body is in a state of perfect health.

1. The first characteristic is the suddenness of their appearance and the rapidity of their progress towards a fatal termination. Some of them act instantaneously, and the effects of most of them are in general fully developed within an hour or little more. But this character is by no means uniform. The most violent may be made to act, so as to bring on their peculiar symptoms slowly, or even by imperceptible degrees. Thus arsenic, which usually causes violent symptoms from the very beginning, may be so administered as to occasion at first nothing more than slight nausea and general feebleness; and afterwards in slow succession its more customary effects. In like manner corrosive sublimate may be given in such a way as to cause at first mild salivation, and finally gangrene of the mouth. Even many vegetable poisons might be administered in the same way. The well-known consequences of digitalis in medicinal doses will serve as a familiar instance. A still better illustration is supplied by the medicinal effects of the alkaloid of nux-vomica, whose action in other circumstances is most rapid and violent: Strychnia in a moderate dose will cause death by violent tetanus in two or three minutes; but when given in frequent small doses as a remedy in palsy, it has been known to bring on first starting of the limbs, then stiffness of the jaw, afterwards pain and rigidity of the neck; and these effects might be increased so gradually, that the patient would seem to die under ordinary tetanus. Nevertheless, the foregoing considerations being kept always in mind, it still remains true, that the effects of poisons for the most part begin suddenly, when the dose is large. This is an important circumstance in regard to certain active poisons, such as the mineral acids, oxalic acid, arsenic, strychnia, &c. For when it is considered that in criminal cases they are given for the most part in unnecessarily large doses, it follows that if the effect ascribed to these poisons in such doses have not begun suddenly, the suspicion is probably incorrect.

The same remarks may be applied to the sudden termination of the symptoms. Poison is for the most part given criminally in doses so large that it proves rapidly fatal. Yet this is not always the case; the diseased state occasioned by poisons has often been prolonged, as will be seen hereafter, for several weeks, sometimes for several months; nay, a person may be carried off by a malady, the seeds of which have been sown by the operation of poison years before.

The present would be the proper place for noticing the important question regarding the interval of time, after which, if death supervenes, it cannot be laid to the charge of the person who administered the poison. It is unnecessary, however, to say much on the subject. According to the English law, death must take place within a year. As to the Scottish law, it may be inferred from what has been said by the late Baron Hume on the subject of homicide generally, that a charge of poisoning is relevant although the person should die at a period indefinitely remote, and that it will infer the pains of law, provided the operation of the poison can be distinctly traced, unmodified by extraneous circumstances, from the commencement of the symptoms to the fatal termination.[^[69]] Of course the influence of these modifying circumstances in lessening the criminal’s responsibility will increase with the interval. The question for the medical jurist to determine in such a case would therefore be, the distance of time to which death may be delayed in the case of poisoning generally, and in that of the particular poison. This question cannot be answered even with an approach to precision, except in the instance of a few common poisons. Most vegetable and animal poisons prove fatal either in a few days or not at all; but some mineral poisons may cause death after an interval of many days. It appears probable that arsenic may cause death after an interval of several months, and it is well ascertained that the symptoms of poisoning with the mineral acids have continued uninterruptedly and without modification for eight months, and then terminated fatally.

2. The next general characteristic of the symptoms of poisoning is regularity in their increase. It is clear, however, that even this character cannot be universal. For in all cases of slow poisoning by repeated small doses there must be remissions and exacerbations, just as in natural diseases. Besides, as we can seldom watch the symptoms advancing in their simple form, but must endeavour to remove them by remedies, remissions may thus be produced and their tendency to increase steadily counteracted. Farther, some poisons admit of exacerbations and remissions, even when given in one large dose; and there are others, the very essence of whose action is to produce violent symptoms in frequent paroxysms. Of the latter kind are nux vomica, and the other substances that contain strychnia. Of the former kind is arsenic: in cases of poisoning with arsenic it often happens, that after the first five or six hours have been passed in great agony, the symptoms undergo a striking remission for as many hours, and then return with equal or increased violence. Still it is true that on the whole the symptoms of poisoning are steady in their progress; so that this should always be attended to as one of the general characters. In the case of slow poisoning, too, when the most remarkable deviations from it are observed, the very occurrence of exacerbations and remissions, combined with certain points of moral proof, may furnish the strongest evidence possible. Thus, on the trial of Miss Blandy at Oxford in 1752, for the murder of her father, one of the strongest circumstances in proof was, that repeatedly after she gave the deceased a bowl of gruel, suspected to be poisoned, his illness was much increased in violence.[^[70]]

As connected with the present subject, a question might here be noticed that has been discussed on the occasion of various trials, namely, whether the symptoms of poisoning are susceptible of a complete intermission. It cannot be answered satisfactorily, however, except with reference to particular poisons. The property alluded to has been ascribed to several poisons, even to mercury, arsenic, and opium; but oftener, I believe, in consequence of an improper desire on the part of the witness to prove or to perfect their view of the case, than through legitimate induction from facts.

3. Another characteristic is uniformity in the nature of the symptoms throughout their whole progress. This character is the least invariable of them all; for many poisons cause very different symptoms towards the close from those which they cause at the beginning. Arsenic may induce at first inflammation of the alimentary canal, and afterwards palsy or epilepsy; nux-vomica may excite at first violent tetanus, and afterwards inflammation of the stomach and bowels; and corrosive sublimate, after exciting in the first instance inflammation, may prove eventually fatal by inducing excessive ptyalism. In truth, certain changes of this kind in the nature of the symptoms will, in special cases, afford strong presumption, perhaps absolute proof, not only of general poisoning, but even also of the particular poison given. The reason for mentioning so uncertain a character as uniformity in the nature of the symptoms among their characteristics will appear presently.—[pp. [47] & [50].]

4. The fourth characteristic is, that the symptoms begin soon after a meal, or rather, soon after food, drink, or medicine has been taken. The occasions on which we eat and drink are so numerous and so near one another, that unless the poison suspected is one which acts with rapidity, it may be difficult to attach any weight to this circumstance. Some poisons rarely produce their effects till a considerable time after they are swallowed; the poisonous mushrooms, for example, may remain in the alimentary canal for several hours or even an entire day and more, before their effects begin; poisonous cheese in like manner may not act for five or six hours,[^[71]] or even a whole day;[^[72]] and that kind of cholera, which is caused in some people by putrid, diseased, and new-killed meat, seldom begins, so far as I have observed, till twelve hours or more after the noxious meal. With regard to the commoner poisons, such as arsenic, corrosive sublimate, the mineral acids, oxalic acid, nux-vomica, and the like, it is a good general rule, that the symptoms, if violent from the beginning, must have begun soon after food, drink, or medicine has been taken.

In making inquiries respecting this point, however, care must be taken not to lose sight of certain circumstances which may cause a deviation from the general rule.

In the first place, it should be remembered that poisons may be administered in many other ways besides mixing them with articles of food or drink, or substituting them for medicines. They may be introduced into the anus; they have been introduced into the vagina; they have also been introduced by inhalation in the form of vapour; and there can be no difficulty in introducing some of them through wounds.

Secondly, another circumstance which may be kept in view is, that, if a person falls asleep very soon after swallowing a poison, especially one of the irritants, the commencement of the symptoms may be considerably retarded, provided it be not one of the powerful corrosives. This statement is not so fully supported by facts as to admit of its being laid down with confidence as a general rule. But from various incidents which have come under my notice it appears not improbable, that sleep does possess the power of putting off for a while the action of some poisons. In particular some instances have occurred to me where arsenic taken at night did not begin to act for several hours, the individual having in the meantime been asleep.[^[73]] The occurrence of so long an interval between its administration and the first appearance of the symptoms is so contrary to what generally happens, that some cause or another must be in activity; and the insensibility of the system during sleep to most sources of excitement seems to supply a sufficient explanation. The slow operation of laxatives during sleep compared with their effects during one’s waking hours, is an analogical fact.

A third consideration to be attended to is, that poison may be secretly administered during sleep to a person who lies habitually with his mouth open. This is fully proved by an interesting case which will be noticed under the head of the moral evidence of poisoning. In that particular case the individual immediately awoke, because the poison was concentrated sulphuric acid; but it may admit of question whether a sound sleeper might not swallow less irritating poisons without being awakened. In such circumstances no connexion of course could be traced between the taking of a suspected article and the first appearance of the symptoms.

5. Lastly, the symptoms appear during a state of perfect health. This is an important character, yet not universal; for it cannot be expected to apply to cases of slow poisoning, and poisons may be given while the person is actually labouring under natural disease. Cases of the last description are generally very embarrassing; for if, instead of medicine, a poison be administered, whose symptoms resemble the natural disease, suspicion may not arise till it is too late to collect evidence.

It must be apparent from the preceding observations, that the characters common to the symptoms of general poisoning are by no means universally applicable. Yet on reviewing them attentively it will also appear, that, considering the little knowledge possessed by the vulgar of the action of poisons, and consequently the rude nature of their attempts to commit murder by poisoning, the exceptions to the general statements made above will not be numerous.

It now remains to be seen how far these characters distinguish the symptoms of poisoning from those of natural disease; and

1. As to the suddenness of their invasion and rapidity of their progress, it is almost needless to observe, that many natural diseases commence with a suddenness and prove fatal with a rapidity, which few or no poisons can surpass. The plague may prove instantaneously fatal; and even the continued fever of this country may be fully formed in an hour, and may terminate fatally, as I have once witnessed, at the beginning of the second day. Inflammation of the stomach also begins suddenly and terminates soon. Cholera likewise answers this description: I have known the characters of ordinary cholera fully developed within an hour after the first warning symptom, and frequently in hot climates, nay, in some rare instances even in Britain, it proves fatal in a few hours. Malignant cholera frequently proves fatal in a few hours. Inflammation of the intestines, too, may begin, or at least seem to begin, suddenly and end fatally in a day: One variety of it, now well known to affect the mucous membrane, may remain quite latent till the gut is perforated by ulceration, and then the patient is attacked with acute pain, vomiting, and mortal faintness, and frequently perishes within twenty-four hours.[^[74]] But in particular many organic diseases of the heart prove suddenly fatal, without any previous warning; and this is also true to a certain extent even of apoplexy; for, as will afterwards be seen, it is an error to suppose that apoplexy is always, or even generally, preceded by warning symptoms. The first characteristic, therefore, as applied to the symptoms of poisoning generally, contrasted with those of general disease, must appear by no means distinctive. But opportunities will occur afterwards for showing, that it is sometimes a good diagnostic in the case of particular poisons.[^[75]]

2. As to the uniformity or uninterrupted increase of the symptoms, it is equally the attribute of many common diseases. I am not aware, that in speedily fatal cases of the internal phlegmasiæ a considerable remission is often observed. Apoplexy, too, very frequently continues its course without interruption; and the same may be said of cholera, and indeed of most acute diseases, when they prove rapidly fatal.

3. It was stated above, that the third character, uniformity in kind throughout their progress, is by no means an invariable circumstance. Still less is it distinctive; for many diseases are marked by great uniformity of symptoms. It has been enumerated nevertheless among the general characters of poisoning, because, although its presence can hardly ever add any weight to the evidence in favour of death by poison, its absence may sometimes afford even positive proof in favour of natural death. That is, changes of a certain kind occurring in the symptoms during their progress may be incompatible with the known effects of a particular poison or of all poisons, and capable of being accounted for only on the supposition of natural disease having been at least the ultimate cause of death. This statement, which is one of some importance, is illustrated by a pointed case, that of Charles Munn, mentioned at the close of the present section.

4. In the next place, it was observed that some reliance may be placed on the fact, that the symptoms of poisoning appear very soon after a meal. But we also know this to be the most frequent occasion on which some natural disorders begin. An attack of apoplexy after a hearty meal is a common occurrence. That kind of cholera which follows the immoderate use of acid fruit likewise comes on soon after eating. Sometimes mere excessive distension of the stomach after a meal proves suddenly or instantaneously fatal. Drinking cold water when the body is over-heated likewise causes at times immediate death. It appears that perforation of the stomach, the result of an insidious ulcer of its coats, and likewise rupture of the stomach from mechanical causes, are most apt to occur during the digestion, and therefore soon after the taking of a meal.

These few observations will make it evident that the appearing of violent symptoms soon after eating may arise from other causes besides the administration of poison. At the same time, as the diseases which are apt to commence suddenly at that particular time are few in number, and none of them by any means frequent, it is always justly reckoned a very suspicious circumstance; and when combined with certain points of moral proof, such as that several people, who have eaten together, were seized about the same time with the same kind of symptoms, the evidence of general poisoning becomes very strong indeed. Sometimes the evidence from the date of their commencement after a meal may singly supply strong evidence, as in the case of the mineral acids and alkalis, or corrosive sublimate, which begin to act in a few seconds or minutes.

On the other hand, if the symptoms do not begin soon after food, drink, or medicine has been taken (the circumstances being such as to exclude the possibility of poison being introduced by a wound, by the lungs, or by any other channel but the stomach), the presumption on the whole is against poisoning; and sometimes the evidence to this effect may be decisive. The principle now propounded may be often a very important one in the practice of medical jurisprudence; for when united with a little knowledge of the symptoms antecedent to death, it may be sufficient to decide the nature of the case. Thus it is sufficient, in my opinion, to decide the celebrated case of the Crown Prince of Sweden. The prince, while in the act of reviewing a body of troops on the 28th May, 1810, was observed suddenly to waver on his horse; and soon afterwards he fell off while at the gallop, was immediately found insensible by his staff, and expired in half an hour. As he was much beloved by the whole nation, a rumour arose that he had been poisoned; and the report took such firm root in the minds of all ranks, that a party of military, while escorting the body to Stockholm, were attacked near the city by the populace, and their commander, Marshal Fersen, murdered; and Dr. Rossi, the prince’s physician, after narrowly escaping the same fate, was in the end obliged to quit his native country. Now, no other poison but one of the most active narcotics could have caused such symptoms, and none of them could have proved so quickly fatal unless given in a large dose. It was proved, however, that on the day of his death the prince had not taken any thing after he breakfasted; and an interval of nearly four hours elapsed after that till he fell from his horse. This fact alone, independently of the marks of apoplexy found in the head after death, and the warning symptoms he repeatedly had, was quite enough to show that he could not have died of poison, as it was incompatible with the known action of the only poisons which could cause the symptoms. This is very properly one of the arguments used by the Medical Faculty of Stockholm, which was consulted on the occasion.[^[76]]

The same circumstances will often enable us to decide at once a set of cases of frequent occurrence, particularly in towns,—where the sudden death of a person in a family, the members of which are on bad terms with one another, is rashly and ignorantly imputed to poison, without any particular poison being pointed at; and where, consequently, unless the morbid appearances clearly indicate the cause of death, a very troublesome analysis might be necessary. In several cases of this kind, which have been submitted to me, I have been induced to dispense with an analysis by resting on the criterion now under consideration. The following is a good example.

A middle-aged man, who had long enjoyed excellent health, one afternoon about two o’clock returned home tired, and after having been severely beaten by his wife went to bed. At a quarter past two one of his workmen found him gasping, rolling his eyes, and quite insensible; and he died in a few minutes. As his wife had often maltreated and threatened him, a suspicion arose that he had died of poison, and the body was in consequence examined judiciously by Sir W. Newbigging and myself. The only appearance of disease we could detect was a considerable tuberculation of the septum cordis and anterior parietes of both ventricles. This disease might have been the cause of death; for there is no disease of the heart which may not remain long latent, and prove fatal suddenly. But, as the man never had a symptom referrible to disease of the heart, it was impossible to infer, in face of a suspicion of poisoning, that it must have been the cause of death; since the man might very well have died of poison, the disease of the heart continuing latent. Poisoning, however, was out of the question. The man had taken nothing whatever after breakfasting about nine. Now no poison but one of the most active narcotics in a large dose could cause death so rapidly as in this case; and the operation of such a poison in such a dose could not be suspended so long as from nine till two. An analysis was therefore unnecessary.

5. Little need be said with regard to the symptoms beginning, while the body is in a state of perfect health; because in truth almost all acute diseases begin under the same circumstances. Connected with this subject, however, a point of difference should be noticed which may be of use for distinguishing poisoning by the irritants from acute diseases of the inflammatory kind:—the latter rarely begin without some adequate and obvious natural cause.

On considering all that has now been said regarding the characteristics of the symptoms of general poisoning, as contrasted with those of natural disease, no one can hesitate to allow, that from them alone a medical jurist can never be entitled to pronounce that poisoning is certain. At the same time he must not on that account neglect them. For, in the first place, they are of great value as generally giving him the first hints of the cause of mischief, and so leading him to search in time for better evidence. Next, they will often enable him to say that poisoning was possible, probable, or highly probable; which, when the moral evidence is very strong, may be quite enough to decide the case. Thirdly, although they can never entitle him to say that poisoning was certain, they will sometimes enable him to say, on the contrary, that it was impossible. And to conclude, when the chemical or moral evidence proves that poison was given, the characters of the symptoms may be necessary to determine whether it was the cause of death.

As the last statement is one of consequence, and yet has been overlooked by some authors on medical jurisprudence in this country, it may be illustrated by one or two comments. It does not follow, because a poison has been given, that it is the cause of death; and therefore in every medico-legal inquiry the cause of the first symptoms and the cause of death should be made two distinct questions. The question, whether a poison, proved to have been administered, was the cause of death, is to be answered by attending to the second and third characteristics mentioned above, and considering whether the symptoms went on progressively increasing, or altered their nature during the course of the patient’s illness, and whether the alteration, if any, was such as may occur in the case of poisoning generally, or of the special poison given. These remarks are very well exemplified by a case, of which I have related the particulars elsewhere,[^[77]] that, namely, of Charles Munn, tried at the Inverary Spring Circuit of 1824 for the double crime of procuring abortion, and of murder by poisoning. The moral evidence and symptoms together left no doubt that arsenic had been given, and that the deceased, a girl with whom the prisoner cohabited, laboured under the effects of that poison in a very aggravated and complex form for twelve days. After that she began to recover rapidly, and in the course of a fortnight more was free of every symptom except weakness and pains in the hands and feet: In short, all things considered, she was thought to be out of danger. But she then became affected with headache and sleeplessness, and died in nineteen days more under symptoms of obscure general fever, without any local inflammation. Dr. Duncan, junior, and I, who were consulted by the Crown in this case, were of opinion,—that granting the girl’s first illness, as appeared from moral and medical evidence, was owing to arsenic, her death could not be ascribed to it with any certainty. It is true that in a few instances the primary irritant symptoms caused by arsenic have been known to pass into an obscure general fever, which has ended fatally; and that this mode of termination coincides with the effects ascribed to arsenic as the chief ingredient in the celebrated Aqua Toffana. But the latter phenomena, at best of doubtful authenticity, are not represented to have been preceded by the ordinary symptoms of violent irritation, or to have been developed except under the use of continuous small doses; and as for the more recent and less ambiguous cases of fever succeeding the usual primary effects of a large dose, in no instance yet recorded was there an intermission between the two stages.

So much, then, for the force of the evidence drawn from the characters of the symptoms of general poisoning. According to the example of others, I might consider in the present place the force of evidence derived from the symptoms themselves, which distinguish the three classes of poisons. But this subject, together with the special natural diseases which imitate the symptoms of poisoning, will be treated of more conveniently as an introduction to each of the classes.

Section II.—Of the Evidence from Morbid Appearances.

The appearances left in the dead body after death by poison used formerly to be relied on as strongly as the symptoms during life; and with even less reason. Except in the instance of a very few poisons, the morbid appearances alone can never distinguish death by poison from the effects of natural disease, or from some other kinds of violent death. There is not much room, therefore, for general remarks under the present head.

It was at one time thought by the profession, and is still very generally imagined by the vulgar, that unusual blackness or lividity of the skin, indicates death by poison generally. But every experienced physician is now well aware, that excessive lividity is by no means universally produced by poison, and that it is likewise produced by so many natural diseases as not even to form, in any circumstances whatever, the slightest ground of suspicion. Neither is there any difference in kind, as some imagine, between the lividity which succeeds death by poison, and that which follows natural death. Yet it is right for the medical jurist to be aware that lividity as a supposed consequence of poison ought to be strictly attended to by medical inspectors and law officers while investigating charges of poisoning, because the vulgar belief on the subject sometimes leads to such conduct or language on the part of the poisoner as betrays his secret at the time, and constitutes evidence of his guilt afterwards.

Another appearance equally unimportant is early putrefaction of the body. Early putrefaction, at one time much insisted on as a criterion of poisoning,[^[78]] cannot even justify suspicion. It is by no means invariably, or even generally caused by poisons; nay, sometimes a state precisely the reverse appears to be induced;[^[79]] and it is seen quite as frequently after natural death.

Some other appearances, not more conclusive, might also be mentioned here; but they belong properly to the effects of individual poisons, or of classes of poisons, not to those of poisoning generally. It may merely be remarked at present, therefore, that the appearances after death, which are really morbid, and which may be produced by poisons, are, in one great class, the signs of inflammation of the alimentary canal in its progressive stages,—in another class, the signs of congestion within the head,—and in a third, a combination of the effects of the two preceding classes; that neither set of appearances is invariably caused by the poisons which usually cause them; that congestion within the head is really seldom produced by those which are currently imagined to produce it; and that most of the appearances of both kinds are exactly similar to those left by many natural diseases.

But although, on the whole, the appearances after death, when considered singly, can seldom supply evidence of poisoning even to the amount of probability, they may nevertheless prove very important under other points of view. Thus, in connection with the symptoms and the general evidence, the appearances after death may furnish decisive proof; and even should the history of the symptoms be unknown, or have been unskilfully collected, the appearances after death, by pointing out the nature of the previous illness, may furnish evidence enough to decide the case, when the moral proof is strong. Again, in cases of alleged imputation of poisoning they are necessary to determine whether a poison actually found in the body was introduced during life or after death. Besides, the very absence of morbid appearances may afford presumptive proof in some circumstances,—when, for example, the question is, whether a person has died of apoplexy or of poisoning with narcotics? Farther, a few poisons, as was formerly stated, occasionally produce appearances so characteristic, as not to be capable of being confounded with the effects of any other agent whatsoever: It will be found hereafter, for example, that the mineral acids have at times left behind them in the dead body unequivocal evidence of their operation. And finally, in cases where no doubt can be entertained that poison was taken, the evidence from morbid appearances may be useful or necessary for settling whether or not it was the cause of death. Two pointed examples of this kind will be noticed under the next section.

When signs of the action of poison are not found in the dead body, and on the contrary marks are found of the operation of natural disease, the presumption of course is that the person died a natural death. But here a few words of caution must be added with regard to the drawing of that inference in cases where the history of the symptoms is not known. It does not follow merely because certain appearances of natural disease are found, that their cause was the cause of death. For death may have arisen from a totally different cause, such as poisoning. This remark is not, as some may imagine, the offspring of hypothetical refinement, but a necessary caution, drawn from actual and not unfrequent occurrences. Thus, for example, the following cases will show, that there may be found in the dead body diseased appearances, arising from pleurisy, hydrothorax, or peripneumony, sufficient to cause death, or to account for death in ordinary circumstances; and that nevertheless the disease may have been completely latent, and death have arisen from poison. In Rust’s Magazin is related the case of a German apothecary, who poisoned himself with prussic acid, and in whose body the lower lobe of the left lung was found consolidated and partly cartilaginous.[^[80]] In Corvisart’s Journal an army-surgeon has described the case of a soldier, who died of a few hours’ illness, and whose right lung was found after death forming one entire abscess; yet to the very last day of his existence he daily underwent all the fatigues of a military life; and in fact he died of poisoning with hemlock.[^[81]] In Pyl’s Memoirs and Observations, there is a similar account of a woman who enjoyed tolerable health, and died during a fit of excessive drinking, and in whose body the whole left lung was found one mass of suppuration.[^[82]] Under the next section will be mentioned other equally pointed cases of death by poison, where the apparent cause of death was external violence.

The conclusions to be drawn from these facts are that, at all events, the medical inspector in a question of poisoning, must take care not to be hurried away by the first striking appearances of natural disease which he may observe, and so be induced to conduct the rest of the inspection superficially; and likewise, that he should not so frame his opinion on the case, as to exclude the possibility of a different cause from the apparent one, unless the appearances are such as must necessarily have been the cause of death. It may be said, that in requiring this condition for an unqualified opinion, a rigour of demonstration is exacted, which can rarely be attained in practice. But, on the one hand, it must not be forgotten, that an unqualified opinion is not always necessary; and on the other hand, although it were, I think it might be shown, if the subject did not lead to disproportionate details, that we may often approach very near the rigour of demonstration required. At present no more need be said, than that the inspector should be particularly on his guard in those cases, in which the appearances, though belonging to the effects of a deadly disease, are trifling; and still more in those in which the appearances, though great, belong to the effects of a disease, whose whole course may be latent. And I may add, that, from what I have observed of medico-legal opinions, the caution now given is strongly called for.

It may be right to allude here also to another purpose which may be served by a careful consideration of the morbid appearances. In cases in which the history of the symptoms is unknown or imperfect the extent and state of progress of the appearances will sometimes supply strong presumptive evidence of the duration of the poisoning. This is an obvious and important application of the knowledge of the pathology of poisoning; but the simple mention of it is all which can be here attempted, as special rules can hardly be laid down on the subject.

Section III.—Evidence from Chemical Analysis.

The chemical evidence in charges of poisoning is generally, and with justice, considered the most decisive of all the branches of proof. It is accounted most valid, when it detects the poison in the general textures of the body, or in the blood, or in the stomach, intestines or gullet, then in the matter vomited, next in articles of food, drink or medicine of which the sufferer has partaken, and lastly, in any articles found in the prisoner’s possession, and for which he cannot account satisfactorily.

When poison is detected in any of these quarters, more especially in the stomach or intestines, it is seldom that any farther proof is needed to establish the fact of poisoning. In two circumstances, however, some corroboration is necessary.

In the first place, in cases where a defence is attempted by a charge of imputation of poisoning it may be necessary to determine by an accurate account of the symptoms, or by the morbid appearances, or by both together, whether the poison was introduced into the body before or after death. For it is said, that attempts have been made to impute crime by introducing poison into the stomach or anus of a dead body; and although I have not been able to find any authentic instance of so horrible an act of ingenuity having been perpetrated, it must nevertheless be allowed to be quite possible.

Secondly, an account of the symptoms and morbid appearances is still more necessary, when the question at issue is, not so much whether poison has been given, as whether it was the cause of death, granting it had been taken. Some remarks have been already made on this question in the two former sections. In the present place some farther illustrations will be added from two very striking cases. They are interesting in many respects, and particularly as showing the importance of strict medico-legal investigation: I am almost certain that but a few years ago their real nature would not have been discovered in this country. The first to be noticed occurred to Dr. Wildberg of Rostock. Wildberg was required to examine the body of a girl, who died while her father was in the act of chastising her severely for stealing, and who was believed by all the bye-standers, and by the father himself, to have died of the beating. Accordingly, Wildberg found the marks of many stripes on the arms, shoulders and back, and under some of the marks blood was extravasated in considerable quantity. But these injuries, though severe, did not appear to him adequate to account for death. He therefore proceeded to examine the cavities; and on opening the stomach, he found it very much inflamed, and lined with a white powder which proved on analysis to be arsenic. It turned out, that on the theft being detected the girl had taken arsenic for fear of her father’s anger, that she vomited during the flogging, and died in slight convulsions. Consequently, Wildberg very properly imputed death to the arsenic. In this case the chemical evidence proved that poison had been taken; but an account of the symptoms and appearances was necessary to prove that she died of it.[^[83]] The other case occurred to Pyl in 1783. A woman at Berlin, who lived on bad terms with her husband, went to bed in perfect health; but soon afterwards her mother found her breathing very hard, and on inquiring into the cause discovered a wound in the left side of the breast. A surgeon being immediately sent for, the hemorrhage which had never been great, was checked without difficulty; but she died nevertheless towards morning. On opening the chest it appeared that the wound pierced into it, and penetrated the pericardium, but did not wound the heart; and although the fifth intercostal artery had been divided, hardly any blood was effused into the cavity of the chest. Coupling these circumstances with the trifling hemorrhage during life, and the fact that she had much vomiting, and some convulsions immediately before death, Pyl satisfied himself that she had not died of the wound: and accordingly the signs of corrosion in the mouth and throat, and of irritation in the stomach, with the subsequent discovery of the remains of some nitric acid in a glass in her room, proved that she had died of poison.[^[84]]

Causes of the disappearance of poison from the body.—Chemical evidence is not always attainable in cases of poisoning. Various causes may remove the poison beyond reach. Hence although poison be not detected in the body,—the experimenter being supposed skilful and the poison of a kind which is easily discovered,—still it must not be concluded from that fact alone that poison has not been the cause of death. For that which was taken into the stomach may have been all discharged by vomiting and purging, or may have been all absorbed, or decomposed; and that which has been absorbed into the system may have been all discharged by the excretions.

1. It may have been discharged by vomiting and purging. Thus on the trial of George Thom for poisoning the Mitchells, held at Aberdeen at the Autumn Circuit of 1821, it was clearly proved, that the deceased had died of poisoning by arsenic; yet by a careful analysis none could be detected in the stomach or its contents; for the man lived seven days, and during all that time laboured under frequent vomiting.[^[85]] In a remarkable case related by Dr. Roget, arsenic could not be found in the matter vomited twenty-four hours after it had been swallowed;[^[86]] in another related by Professor Wagner of Berlin, that of an infant who died in twelve hours under incessant vomiting after receiving a small quantity of arsenic, none could be detected in the stomach;[^[87]] in another which I have described in a paper on arsenic, although the person lived only five hours, the whole arsenic which could be detected in the tissues and contents of the stomach did not exceed a fifteenth part of a grain;[^[88]] in an American Journal there is a striking case of a grocer, who died eight hours after swallowing an ounce of arsenic, and in whose body none could be found chemically,—at a period however antecedent to the late improvements in analysis;[^[89]] and in a case communicated to me not long ago by Mr. Hewson of Lincoln, where arsenic was given in solution, and death ensued in five hours, none of the poison could be detected either in the contents or tissues of the stomach by a careful analysis conducted according to the most modern principles.

Nevertheless, it is singular how ineffectual vomiting proves in expelling some poisons from the stomach. Those which are not easily soluble, and have been taken in a state of minute division, may remain adhering to the villous coat, notwithstanding repeated and violent efforts to dislodge them by vomiting. Many instances to this effect have occurred in the instance of arsenic. Metzger has related a case, where, after six hours of incessant vomiting, three drachms were found in the stomach.[^[90]] Mr. Sidey, a surgeon of this city, has mentioned to me an instance of poisoning with king’s yellow, in which he found the stomach lined with the poison, although the patient had vomited for thirty hours. In three cases which I have investigated arsenic was detected, although the people lived and vomited much for nearly two days;[^[91]] and Professor Orfila has noticed a similar instance in which that poison was found in the contents of the stomach, although the person had vomited incessantly for two entire days.[^[92]]

It is not easy to specify the period after which a poison that has excited vomiting need not be looked for in the stomach. It must vary with a variety of circumstances whose combined effect it is almost impossible to appreciate, such as the solubility and state of division of the poison, the frequency of vomiting, the substances taken as remedies, and the like. When the poison is in solution and the patient vomits much, an analysis may be expected to prove frequently abortive, even though the individual survives but a few hours, as in Mr. Hewson’s case already noticed. In other circumstances, however, as various facts quoted above will show, poisons may frequently be found after two days incessant vomiting; and on the whole it may be stated, that the recent improvements in analysis render the period much longer than it has generally been, and would naturally be imagined. Metzger has related the case of a woman poisoned with arsenic mixed with currants, in whose body, after eight days of frequent vomiting, he found ten or twelve currants, which gave out an odour of garlic when burnt;[^[93]] but here the dose, if there was really arsenic, must have been repeated recently before death, for it is not possible to conceive how currants could remain in the stomach so long, whatever may be thought of the possibility of arsenic remaining. It is farther proper to add, that Professor Henke of Erlangen, one of the highest living authorities in Germany, once found grains of arsenic in the gullet, although he found none in any other part of the body, of a person who survived the taking of the poison four days.[^[94]] Allowing to this fact all the weight derived from the high name of its author, I must nevertheless express great doubt whether the arsenic was not repeated more recently before death.

2. The poison may have disappeared, because it has been all absorbed. It has several times happened that in the bodies of those poisoned with laudanum, or even with solid opium, none of the drug could be detected after death. Sometimes indeed it is found, even though the individual survived the taking of the poison many hours. Thus a case related by Meyer of Berlin, in which the person lived ten hours after taking the saffron-tincture of opium; and nevertheless it was detected in the stomach by a mixed smell of saffron and opium.[^[95]] But more commonly it all disappears, unless the dose has been very large. In a case of poisoning with laudanum, which I examined here along with Sir W. Newbigging in 1823, none could be detected, although strong moral circumstances left no doubt that laudanum had been swallowed seven or eight hours before death. An instance of the same kind has been minutely related by Pyl. It was that of an infant who was poisoned with a mixture of opium and hyoscyamus, and in whose stomach and intestines none could be detected by the smell.[^[96]] Similar observations have been often made on animals; and several additional cases of the same purport, occurring in man, will be related under the head of opium.

It might be of use to quote some of the numerous errors committed by medical witnesses, in consequence of having overlooked the effect of absorption in removing poisons beyond the reach of chemical analysis. But not to be too prolix, I shall be content with mentioning a single very distinct case in point, which happened at a Coroner’s Inquest in London, in 1823. A young man one evening called his fellow-lodger to his bedside; assured him he had taken laudanum, and should be dead by the morrow; and desired him to carry his last farewell to his mother and his mistress. His companion thought he was shamming; but next morning the unfortunate youth was found in the agonies of death. The moral evidence was not very satisfactory; but that is of little consequence to my present object. The point in the case I would particularly refer to is the declaration of the medical inspector, that laudanum could not have been taken, because he did not find any by the smell or by chemical analysis in the contents of the stomach.[^[97]]

3. Poisons may not be found, because the excess has been decomposed.

Vegetable and animal poisons may be altogether destroyed by the process of digestion. This observation will explain why sometimes no poison could be found in cases of poisoning with crude opium or other vegetable solids. A French physician, M. Desruelles, has related the case of a soldier, who died six hours and a half after swallowing two drachms of solid opium, and in whose stomach nothing was found but a yellowish fluid, quite destitute of the smell of the drug.[^[98]]

Some mineral poisons, such as corrosive sublimate, lunar caustic, and hydrochlorate of tin, are also decomposed in the stomach. But they are not removed beyond the reach of chemical analysis. The decomposition is the result of a chemical, not of a vital process; and the basis of the poison may be found in the solid contents of the stomach under some other compound form. Other poisons again may be apt to elude detection by altering their form, by combining with other substances, without themselves undergoing decomposition. Thus it appears from a case related by Mertzdorff of Berlin, that, in poisoning with sulphuric acid, after the greater part of the poison is discharged by vomiting, the remainder may escape discovery by being neutralized: For, although he could not find any free acid in the contents of the stomach, he discovered 4½ grains in union with ammonia by precipitation with muriate of baryta.[^[99]]

It may be also right to mention another kind of decomposition which may render it impossible to detect a poison that has been really swallowed—namely, that arising from decay of the body. In several recent cases bodies have been disinterred and examined for poison months or even years after death. In these and similar cases it would be unreasonable to expect always to find the poison, even though it existed in the stomach immediately after death. Some poisons, such as oxalic acid, might be dissolved and then exude; others, such as the vegetable narcotics, will undergo putrefaction; and others, such as prussic acid, are partly volatilized, partly decomposed, so as to be undistinguishable in the course of a few days only. The mineral poisons, those at least which are solid, are not liable to be so dissipated or destroyed. Some authors, indeed, have said that arsenic may disappear in consequence of its uniting with hydrogen disengaged during the progress of putrefaction, and so escaping in the form of arseniuretted-hydrogen gas; and they have endeavoured to account in this way for the non-discovery of it in the bodies of the people who had been killed by arsenic, and disinterred for examination many months afterwards.[^[100]] But the supposition is by no means probable: at least arsenic has been detected in the body fourteen months, nay, even seven years, after interment. For farther details, on this curious topic, the reader may turn to the article Arsenic.

On the whole, the result of the most recent researches is that the effect of the spontaneous decay of dead animal matter in involving poisons in the general decomposition appears to be much less considerable than might be anticipated. For this most important medico-legal fact, the toxicologist is indebted to the experimental inquiries of MM. Orfila and Lesueur.[^[101]] The poisons tried by them were—sulphuric and nitric acids, arsenic, corrosive sublimate, tartar-emetic, sugar of lead, protomuriate of tin, blue vitriol, verdigris, lunar caustic, muriate of gold, acetate of morphia, muriate of brucia, acetate of strychnia, hydrocyanic acid, opium, and cantharides. They found that after a time the acids become neutralized by the ammonia disengaged during the decay of animal matter;—that by the action of the animal matter the salts of mercury, antimony, copper, tin, gold, silver, and likewise the salts of the vegetable alkaloids, undergo chemical decomposition, in consequence of which the bases become less soluble in water, or altogether insoluble;—that acids may be detected after several years’ interment, not always, however, in the free state;—that the bases of the decomposed metallic salts may also be found after interment for several years;—that arsenic, opium, and cantharides undergo little change after a long interval of time, and are scarcely more difficult to discover in decayed, than in recent animal mixtures;—but that hydrocyanic acid disappears very soon, so as to be undistinguishable in the course of a few days.

4. Lastly, the poison which has been absorbed into the system, and may consequently be detected in certain circumstances in the textures of the body at a distance from the alimentary canal, may also be removed beyond the reach of analysis, by being gradually discharged along with the excretions. It has been fully proved in recent times, that in poisoning with arsenic the poison may be found in ordinary cases, for some days after being swallowed, in the liver especially, but also in the other textures, in the blood, and in the urine; but that if a flow of urine be established and kept up, in nine or ten days, and sometimes much sooner, it can no longer be discovered anywhere by the nicest analysis.[^[102]]

Is the discovery of poison in the body or the evacuations essential to establish a charge of poisoning? It was mentioned at the commencement of the present section, that the chemical evidence is generally, and correctly, considered the most decisive of all the branches of proof in cases of poisoning. But some toxicologists have even gone so far as to maintain that without chemical evidence, or rather, in more general terms, without the discovery of poison either in the body itself or in the evacuations,—no charge of poisoning ought to be held as proved. This, however, is a doctrine to which I cannot assent. In the preceding observations on the evidence of general poisoning it has been several times alluded to as unsound; and repeated opportunities of establishing exceptions will occur in the course of this work, under the head of individual poisons. At present it may be well to illustrate its unsoundness in reference to those charges of poisoning, where no particular poison is pointed at by the medical evidence, but where a whole class of poisons must be kept more or less in view. Even here I apprehend there may be sufficient evidence in the symptoms and morbid appearances, without any chemical facts,—to render poisoning so highly probable, that in conjunction with strong moral evidence, no sensible man can entertain any doubt on the subject. Several illustrations might be here given; and some will be found scattered throughout the work. In the present place a few instances will be mentioned which cannot be conveniently arranged any where else, and which are well worthy of notice, as being striking examples of the decision of questions of poisoning without chemical evidence.

A man of doubtful character and morals, well acquainted with chemistry and medical jurisprudence, and of disordered finances, was known to harbour a design on a friend’s wife, who possessed a considerable fortune. At last he one morning invited the husband to breakfast with him at a tavern; and they breakfasted, in a private apartment, on beef-steaks, fried potatoes, eels, claret, and rum. They had scarcely commenced the meal when his guest complained of feeling unwell; and soon afterwards he vomited violently. This symptom continued, along with excruciating pain in the belly, for a long time before the prisoner sent for medical aid; indeed he did not procure a physician till the sufferer had been also attacked with very frequent and involuntary purging. The physician, who, before seeing his patient, had received the prisoner’s explanation of the apparent cause of the illness, was led at first to impute the whole to cholera caught by exposure to cold; but on returning at seven in the evening, and finding the gentleman had been dead for an hour, he at once exclaimed that he had been poisoned. On the body being inspected much external lividity was found, contraction of the fingers, and great inflammation of the stomach and intestines, presenting an appearance like that of gangrene.[^[103]] On analyzing some fluid left in the stomach, no arsenic or other poison could be detected. The attention of the inspectors was turned specially to arsenic, because the prisoner was proved to have bought that poison, and to have made a solution of some white powder in his kitchen not long before the deceased died. The prisoner in his defence stated, that the deceased had been for some time much weakened by the use of mercury, and while in this state was seized with cholera; and he likewise attempted to make it probable that the man, in despair at his not recovering from a venereal disease, might have committed suicide. The council of physicians who were required to give their opinion on the case state on the contrary, that the diseased was a healthy man, without any apparent disposition to disease; that there was no pretext whatever for supposing suicide; that the inflammatory state of the stomach and bowels supplied strong probability of poisoning with arsenic, but not certain evidence; that acute gastritis from natural causes is always attended with constipation; that the deceased presented symptoms of stupor and other signs of derangement of the nervous system remarked in rapid cases of poisoning with arsenic; that cholera is very rare at the end of November, the season when this incident occurred; and that the poison might well be discharged by vomiting. Although all the prisoner’s statements in defence were contradicted by satisfactory proof, and the medical evidence of poisoning was supported by a chain of the strongest general circumstances, the crime was considered by the court as not fully proved, because the prisoner could not be induced to confess, and because poison was not actually detected in the body. But on account of the very strong probability of his guilt, he was, in conformity with the strange practice of German courts in the like cases, condemned to fifteen years’ imprisonment.[^[104]] In this instance—considering the kind of symptoms, their commencement during a meal, the rapidity of death, the signs of violent inflammation in the stomach after so short an illness, and the facility with which the absence of poison in the contents of the stomach may be accounted for, more especially if it be supposed that the poison was administered in solution,—I consider the medical evidence of death by poisoning so very strong, that, the general evidence being also extremely strong, the prisoner’s guilt was fully demonstrated.

A case of the same kind, but of still greater interest, is that of Mary Anne M’Conkey, who was tried at the Monaghan Assizes in 1841 for the murder of her husband. I am indebted for the particulars to Dr. Geoghegan, one of the principal Crown witnesses. The prisoner who had been too intimate with another man, and had been heard to express her intention of getting rid of her husband, was observed one day before dinner to separate some greens for him from the plateful intended for the rest of the family. None of the latter suffered at all. But her husband was taken violently ill immediately after dinner, and died; and a neighbour accidentally present, who partook, though sparingly, of the same dish with him, was also similarly and violently affected but recovered. The deceased before finishing the greens said they had a disagreeable sharp taste, and was seized soon after with burning at the heart, tenderness at the pit of the stomach, vomiting, coldness, a sense of biting in the tongue and tingling through the whole flesh, excessive restlessness, occasional incoherence, locked-jaw, clenching of the hands, and frothing at the mouth; and he expired three hours after the meal. His neighbour, two minutes after finishing his greens, experienced a sense of pricking in the mouth and burning in the throat, gullet, and stomach; then salivation, a feeling of swelling in the face without actual fulness, general numbness and creeping in the skin; next excessive restlessness, coldness of the integuments, dimness of sight, and stupor; about an hour after the meal he became speechless, repeatedly fainted, frothed at the mouth, and clenched his hands; vomiting ensued, with considerable relief, and subsequently he had frequent attacks of it, with purging, tenderness of the epigastrium, cramps, and tingling in the flesh; and from these symptoms he recovered so slowly as to be unable to work for five weeks. The only morbid appearance of any note in the body of the deceased was a number of irregular brownish-black patches on the inside of the stomach. No poison could be detected in the contents or tissues of the stomach; none could be discovered in the house except a corrosive-sublimate solution which the prisoner used for a gargle; and none could be traced into her possession. A variety of circumstances of a general nature, which are passed over here for brevity, as not strictly appertaining to the present view of the case, threw very great suspicion over the prisoner. The medical witnesses deposed, that poisoning could alone explain the medical circumstances; and Dr. Geoghegan was of opinion that death was owing to some vegetable poison, although he could not specify the particular substance. He suspected, however, that it was monkshood. In these views, when consulted by him before the trial, I entirely concurred. Considering the taste observed by the deceased at the time he ate the greens, the rapidity with which he was taken ill afterwards, and the very peculiar symptoms, unlike those of any natural disease with which physicians are acquainted, and agreeing with those which are produced by monkshood,—considering also that another individual, who partook of the same dish with him, was similarly and simultaneously attacked, and with a severity proportioned to the quantity he took, while other persons who ate the same food from a different dish, did not suffer at all,—it appears to me that poisoning was clearly established; and I also think that the general evidence brought home the charge of administering the poison to the prisoner. She was condemned and executed, and confessed before execution, that she did poison her husband, and that the substance she used was the powdered root of monkshood, which is well known as a poison to the peasantry of Monaghan under the name of Blue Rocket.

It is scarcely necessary to add, that great caution must be observed in applying the general principle here inculcated. But the opposite doctrine, that no charge of poisoning can be established without the discovery of poison in the body or in the evacuations, appears to me a great error, though upheld by no mean authority. Under that doctrine few criminals would be brought to justice, were they to resort to a variety of vegetable poisons, which in certain seasons are within the reach of every one.

Section IV.—Evidence from Experiments on Animals.

Evidence from experiments on animals with articles supposed to contain poison is more equivocal than was once imagined. But it may be doubted whether some medical jurists have not overstepped the proper limits, when they hold it to constitute little or no proof at all.

Evidence from express experiments should rarely form part of a regular medical inquiry into a charge of poisoning. For in the first place, to make sure of performing an experiment well requires more experimental skill than the generality of practitioners can be expected to possess; then, as will seen in the sequel, evidence procured from this source can very rarely be more than presumptive; and lastly, if the quantity of poison in the suspected substance is great enough to affect one of the perfect animals, it may generally be recognized to a certainty by its physical or chemical properties.

For these reasons it is not likely, that, in an inquiry undertaken by a skilful toxicologist, he will put himself in the way of delivering an opinion on the force of such evidence. But it is nevertheless necessary for me to consider it in detail, because he may have to give his opinion regarding experiments made inconsiderately by others, or accidents caused by domestic animals eating the remains of substances suspected to be poisoned.

The matter subjected to trial may be either suspected food, drink, or medicine; or it may be the stuff vomited during life, or found in the stomach after death; or it may be the flesh of poisoned animals.

1. The evidence derived from the effects of suspected food, drink, or medicine is better than that drawn from the effects of the vomited matter or contents of the stomach. But an important objection has been made to both, namely, that what is poison to man is not always poison to the lower animals, and that, on the other hand, some of the lower animals are poisoned by substances not hurtful to man.

A good deal of obscurity still hangs over the relative effects of poisons on man and the lower animals. There are two species, however, whose mode of life in respect to food closely resembles our own, and which, according to innumerable experiments by Orfila, are affected by almost all poisons exactly in the same way as ourselves, namely, the cat and dog, but particularly the latter.

In general poisons act less violently on these animals; thus two drachms of opium are required to kill a middle-sized dog,[^[105]] while twenty grains have killed a man, and undoubtedly less would be sufficient. It appears that one poison, alcohol, acts more powerfully on them than on man. There are also some poisons, such as opium, which, although deleterious to them as well as to man, nevertheless produce in general different symptoms. Yet the differences alluded to are probably not greater than exist between man and man in regard to the same substances; and therefore it may be assumed, that, on the whole, the effects of poisons on man differ little from those produced on the dog and cat.

The present objection is generally and perhaps justly considered a stronger one, when it is applied to other species of animals. But it must be confessed after all, that our knowledge of the diversities in the action of poisons on different animals is exceedingly vague, and founded on inaccurate research; and there is much reason to suspect, that, if the subject is studied more deeply, the greater number of the alleged diversities will prove rather apparent than real. Both reasoning and experiment, indeed, render it probable, that some orders, even of the perfect animals, such as the Ruminantia, are much less sensible than man to many poisons, and especially to poisons of the vegetable kingdom. But so far as maybe inferred from the only accurate inquires on the subject, their effects differ in degree more than in kind. Some exceptions will without doubt be found to this statement. For example, oxalic acid, besides inflaming the stomach, causes violent convulsions in animals, but in man it for the most part excites merely excessive prostration; and opium most generally excites in man pure sopor, in animals convulsions also. Other exceptions, too, exist by reason of functional peculiarities in certain animals. Thus irritant poisons do not cause vomiting in rabbits or horses, because these animals cannot vomit; neither do they appear to cause much pain to rabbits, because rabbits have not the power of expressing pain with energy. But exceptions like these, and particularly such as are unconnected with functional peculiarities, will probably prove fewer in number, and less striking than is currently imagined. For it is, on the other hand, well ascertained, that many, indeed most of the active poisons whose effects have been examined by a connected train of experiments, produce nearly the same effects on all animals whatever from the highest to the lowest in the scale of perfection. It has been fully proved, that arsenic, copper, mercury, the mineral acids, opium, strychnia, conia, white hellebore, hydrocyanic acid, cyanogen gas, sulphuretted hydrogen, and many others, produce nearly the same effects on man, quadrupeds, birds, amphibious animals, and even on fishes and insects.[^[106]]

Accordingly there are cases, in which the evidence from experiments on animals with suspected articles of food is unequivocal. For example;—a sexton and his wife, who had got a bad name in their village in consequence of informing against the bailiff for smuggling, and who were on that account shunned by all the neighbours, accused the bailiff and his wife of having tried to poison them by mixing poison with their bread. Immediately after eating they were attacked, they said, with sickness, griping, swelling, and dizziness; and they added, that a cat was seized with convulsions after eating a part of it, had sprung away, and never returned. A large portion of the loaf was therefore sent to the Medical Inspector of the district; who reported, that it seemed exactly similar to another unsuspected loaf;—that, although he was not able to detect any poison, it might after all contain one,—vegetable poison particularly;—but that he could hardly believe it did, for he fed a dog, a cat, and a fowl several days with it, and they not only did not suffer any harm, but even appeared very fond of it.[^[107]] In this case it was clear that poisoning was out of the question. On the other hand, the effects of some poisons on man may be developed so characteristically in animals as to supply pointed evidence. Thus, in the case of Mary Bateman, an infamous fortune-teller and charm-worker, who after cheating a poor family for a series of years, at last tried to avoid detection by poisoning them, it was justly accounted good evidence, that a portion of the pudding and the honey, supposed to have been poisoned, caused violent vomiting in a cat, killed three fowls, and proved fatal to a dog in four days, under symptoms of irritation of the stomach such as were observed in the people who died.[^[108]]

It has been farther objected to experiments on animals with suspected articles of food, drink, or medicine, that it is difficult to administer poison to them in a state of concentration, and to prevent it from being discharged by vomiting. This objection, however, may be obviated by performing the experiment in the way recommended by Professor Orfila. A small opening is made into the gullet, previously detached from its surrounding connexions, the liquid part is introduced by a funnel thrust into the opening, and the solid portion previously made into little pellets is then squeezed down. Lastly, the gullet is tied under the aperture. The immediate effect of the operation is merely an appearance of languor; and no very serious symptom is observable till four or five days at soonest after the tying of the gullet. Hence if signs of poisoning commence within twenty-four hours, they are independent of the injury done by the operation.[^[109]] This process requires some adroitness to execute it well. It cannot be tried successfully but by a practised operator, who, for reasons already given, would hardly ever try experiments of the kind with suspected articles. Mention is here made of it, therefore, chiefly because it is the best mode of experimenting in those cases in which it is necessary, as will presently be seen, to determine disputed points in the physiology of poisons.

I may here shortly notice a method which has been lately proposed for detecting poisons that enter the blood, and which is founded on their effects on animals. M. Vernière suggests that advantage may be taken of the extreme sensibility of the medicinal leech to procure at least presumptive evidence, when no evidence can be procured in any other manner. He has related some experiments to prove that the leech, when placed in the blood of dogs killed by nux-vomica, is affected even when the quantity of the poison is exceedingly small.[^[110]] It is extremely doubtful whether any importance can be attached to this criterion, as every one knows that the leech is apt to suffer from a variety of obscure causes, and among the rest from some diseased states of the body.

2. In the case of the vomited matter or contents of the stomach there are other and weightier objections to experiments on animals.—In the first place, the poison which has caused death may have been either in part or wholly vomited before-hand, or absorbed, or transmitted into the intestines, or decomposed by the process of digestion. Secondly, though abounding in the matter vomited or which remains in the stomach, it may be so much diluted, as not to have any effect on an animal. And, thirdly, the animal fluids secreted during disease are believed to act occasionally as poisons.

The first two objections are so plainly conclusive as scarcely to require any illustration. It may be well, however, to mention as a pointed practical lesson, that Professor Orfila once detected a considerable quantity of arsenic in the contents of the stomach, where a prior investigation had shown that the same article produced no effect on two animals, and where the reporters from this and other circumstances declared, that in their opinion death was not owing to poison.[^[111]]

The last objection is a very important one; but there is reason for suspecting that it has been a good deal exaggerated by medical jurists.—Animal fluids are certainly poisonous when putrid. The repeated and fatal experience of anatomists, together with the precise experiments of M. Gaspard and M. Magendie,[^[112]] leave no doubt that putrid animal fluids, when introduced into an external wound, cause spreading inflammation of the cellular tissue; and although Magendie says he has found such fluids harmless when introduced into the stomach of dogs,[^[113]] it is probable, from their effects on man, that they will act as irritants on animals not habituated to their use. I believe, too, that independently of putrefaction, vomited matter or the contents of the stomach may be apt to make dogs vomit on account of their nauseous taste; and perhaps we may infer, that they will also cause some of the other symptoms of poisoning with the irritants, particularly if not vomited soon after being administered.—As to the influence of disease in rendering the contents of the stomach deleterious, it is to be observed that the effects just mentioned are probably owing to the influence of disease on the secretions, but that beyond this we know very little of the subject. In authors I have hitherto found only one fact to prove that disease can render the contents of the stomach decidedly poisonous; and on the negative side of the question there exists no facts at all. Morgagni describes the case of a child who died of tertian ague, amidst convulsions, and in whose stomach a greenish bile was found, which proved so deleterious, that a little of it given with bread to a cock caused convulsions and death in a few minutes, and a scalpel stained with it, when thrust into the flesh of two pigeons, killed them in the same manner.[^[114]] It is not easy to say what to think of this experiment; which, if admitted to the full extent of the conclusions deducible from it, would lead to the admission, that disease may impart to the secretions the properties of the most active narcotics. Farther researches are certainly required before this admission can be made unreservedly.

On the whole, it appears that in the present state of our knowledge, experiments or accidental observations on the effects of the contents of the stomach, or of vomited matter, on animals are equivocal in their import. At the same time it may be observed, as with regard to articles of food, drink, or medicine, that the effects of some poisons on man may be developed so characteristically on animals by the contents of the stomach, as to supply very pointed evidence indeed. Of the force of this statement the following example is a striking illustration. In the case of a girl, who was proved to have died of accidental poisoning with laudanum, the inspector evaporated the contents of the stomach to dryness, made an alcoholic extract from the residue, and giving this to several dogs, chickens, and frogs, found that they were all made lethargic by it, some of them oftener than once, and that a few died comatose.[^[115]] Facts such as these, agreeing so pointedly with the known effects of the poison suspected, appear to me to yield evidence almost unimpeachable.

3. The effects of the flesh of poisoned animals, eaten by other animals, constitute the least conclusive of all the varieties of the present branch of evidence. For the flesh of animals that have died of poisoning is not always deleterious; while on the other hand flesh is sometimes rendered so by natural causes, as will be seen in the Chapter on Diseased and Decayed Animal Matter.

This subject stands much in need of careful and methodic investigation. And it is of more practical importance than might be imagined at first sight. For the question has actually occurred in a legal inquiry in this country,—Whether poisoning in the human subject may be caused by the flesh of a poisoned animal?

In regard to some poisons it is well established, that animals killed by them may be eaten with impunity, such as game killed with the wourali poison, or fish by cocculis-indicus. This seems the general rule. But it is not clear that all poisons are similarly circumstanced.

The only systematic researches hitherto undertaken on this question are some recently made at Lucca by Professor Gianelli; of which however I have only seen an abstract. He found that the blood, urine, and lungs of animals poisoned with arsenic acted as a poison on small birds, such as sparrows, whether the parts were taken from the body while the animal was alive, or after death; but that alcohol, cherry-laurel water, corrosive sublimate, sulphate of copper, tartar-emetic, acetate of lead, nitrate of silver, trisnitrate of bismuth, chloride of tin, sulphate of zinc, laudanum, acetate of morphia, strychnia, and cantharides, had no such effect.[^[116]] Orfila has since shown some reason for doubting the conclusiveness of Gianelli’s investigations; and on repeating them, obtained such results as render it doubtful whether any reliance can be put upon experiments made upon small birds.[^[117]] Guérard however has ascertained, that dogs, fed on the flesh and entrails of sheep which had taken arsenic, were attacked with vomiting and purging, became reduced in flesh, and at length would not eat what was put before them; but none of them perished, or seem to have been seriously ill. Arsenic was detected in their urine.[^[118]]

The importance of the inquiry, which the preceding experiments are intended to elucidate, will appear from the following singular case, for the particulars of which I am indebted to the kindness of Mr. Jamieson of Aberdeen, who was employed by the authorities to investigate it. An elderly woman, who kept fowls which occasionally trespassed on a neighbour’s fields, one morning observed four of them very sickly; and in the course of the day they became so ill that she killed them. She cleaned and prepared two of them for cooking, buried another, and gave away the fourth to a beggar, who was afterwards lost sight of. Next day soup made with the half of one of the fowls was given to a little girl, who suffered severely from sickness and vomiting, and also to a cat, which was similarly affected for the whole evening. On the day afterwards the woman herself and a female lodger, took broth made with what remained of the fowls, and also ate the gizzards; but the remainder was thrown with the offal upon the dunghill. In the course of five or six hours both women were attacked with severe illness. One had sickness, vomiting and great coldness; but after encouraging the vomiting with hot water and then taking some spirits, she got better in the night-time, and next morning was pretty well. The other, who was the owner of the fowls, was seized somewhat later than her friend with great thirst and shivering, and next day with pains in the stomach, severe sickness, and fruitless efforts to vomit. On the sixth day, when a medical man first saw her, she had great pain throughout the abdomen, much thirst, difficult breathing, a red, dry tongue, and a very frequent, small pulse. Next day the pain and difficult breathing became worse; and in the evening, after an attack of sneezing, she became gradually insensible and motionless, in which state she remained till the tenth day, when she expired. The stomach and intestines did not present any distinct morbid appearance; but the vessels of the brain were turgid, there were about two ounces of serosity in the lateral ventricles, both corpora striata were softened anteriorly, and a clot of blood as big as an almond was contained in the right anterior lobe of the brain.—A judicial investigation being ordered, it was ascertained that the fowl which the woman buried as well as the remains of the other fowls which were thrown upon the dunghill, had been carried off. But on searching the dunghill more carefully afterwards, the contents of one of the crops, which had been taken out and examined by the lodger, were discovered in the rubbish; and in the mass Mr. Jamieson detected a considerable quantity of arsenic.

This incident happened in 1836. More lately the same gentleman met with another extraordinary attempt of the same kind. A farmer, about to be married, gave directions for killing in the evening some fowls which were to be sent to the house of his bride where the ceremony was to take place. The killing of them however was accidentally delayed; and next morning, on the hen-house door being opened, the fowls ran furiously to the well, drank water incessantly, and died in an hour. On examining the bodies, Mr. Jamieson found arsenic in large quantity in their crops and gizzards.

On each of these occasions a particular individual came under suspicion; but the evidence against them was too slight to justify the authorities in bringing a formal charge; and consequently the proceedings did not go farther. In the former instance the evidence in favour of the flesh of poisoned animals being sometimes poisonous is strong; and the history of the woman’s case, although death seems to have been caused directly by apoplexy, renders it probable that even dangerous results might accrue.

The preceding remarks will enable the medical witness to know under what circumstances accidental observations or intentional experiments on animals furnish satisfactory proof.

Before quitting the subject, however, I have to add, that there is another purpose, besides procuring direct evidence, to which experiments with animals may be applied with great propriety;—namely, the settling disputed questions regarding the physiological and pathological properties of a particular poison. The science of toxicology is not yet by any means so perfect, but in particular cases topics may arise, which have not hitherto been investigated, and which it may be necessary to determine by experiment. Experiments on animals instituted for such purposes by a skilful toxicologist are not liable to any important objection. On the trial of Charles Angus at Liverpool in 1808, for procuring abortion and murder by poison, a trial of great interest, which will be referred to more particularly afterwards, it appeared from the evidence of the crown witnesses, that the poison suspected, corrosive sublimate, could not be discovered in the stomach by certain methods of analysis; and that, although corrosive sublimate is a powerful irritant, the villous coat of the stomach was not inflamed. But then it was proved by experiments made by one of their number, Dr. Bostock, that animals might be killed with corrosive sublimate without the stomach being inflamed, and without the poison being discoverable after death by the tests he used in the case.[^[119]] An attempt was made on the side of the prisoner to throw out this line of evidence as incompetent, on the ground of the discrepant effects of poisons on man and on the lower animals. But it was admitted by the judge, on the plea that it was only to illustrate a general physiological fact, and not to infer proof of poisoning. The importance of experiments on animals to settle incidental physiological questions has lately been again acknowledged in a very pointed manner in an English court of law: for a set of experiments, to settle the question of the rapidity with which hydrocyanic acid acts, was instituted before the trial by the medical witnesses, at the request of the judge who was to try the case.[^[120]]

Section V.—Of the Moral Evidence.

It is not my object to treat under this head of the moral evidence generally, which is required to establish a charge of poisoning. But as it is well known that in criminal trials medical witnesses have for the most part nothing to do with the moral proof, while at the same time in cases of poisoning the medical and moral circumstances are always intimately interwoven and apt to be confounded together, it is necessary for me to specify those particulars of the moral evidence, which either require some medical skill to appreciate them, or fall naturally under the cognizance of the physician in his quality of practitioner. I shall enter into greater details under this section than may perhaps appear to the medical reader necessary, chiefly that I may redeem the pledge given in the introduction to the lawyer and general reader, and endeavour to show how powerful an instrument a medico-legal investigation may become in skilful hands, for throwing light on almost every branch of the evidence.

The moral or general proof in charges of poisoning is almost always circumstantial only. The circumstances of which it usually consists relate, 1. To suspicious conduct on the part of the prisoner before the event, such as dabbling with poisons when he has nothing to do with them in the way of his profession, or conversing about them, or otherwise showing a knowledge of their properties not usual in his sphere of life:—2. To the purchase or possession of poison recently before the date of the alleged crime, and the procuring it in a secret manner, or under false pretences, such as for poisoning rats when there are none on his premises, or for purposes to which it is never applied:—3. To the administration of poison either in food, drink, medicine, or otherwise:—4. To the intent of the prisoner, such as the impossibility of his having administered the poison ignorantly, or by accident, or for beneficial purposes, alleged or not alleged:—5. To the fact of other members of the family besides the deceased having been similarly and simultaneously affected:—6. To suspicious conduct on the part of the prisoner during the illness of the person poisoned,—such as directly or indirectly preventing medical advice being obtained, or the relations of the dying man being sent for, or showing an over-anxiety not to leave him alone with any other person, or attempting to remove or destroy articles of food or drink, or vomiting matter which may have contained the poison, or expressing a foreknowledge of the probability of speedy death:—7. To suspicious conduct after the person’s death, such as hastening the funeral, preventing or impeding the inspection of the body, giving a false account of the previous illness, showing an acquaintance with the real or supposed effects of poison on the dead body:—8. To the personal circumstances and state of mind of the deceased, his death-bed declaration, and other particulars, especially such as tend to prove the impossibility or improbability of suicide:—9. To the existence of a motive or inducement on the part of the prisoner, such as his having a personal quarrel with the deceased, or a hatred of him,—his succeeding to property by his death, or being relieved of a burthen by it,—his knowing that the deceased was with child by him.

Upon many of the particulars now enumerated, important evidence may be derived from the medical part of the investigation; and not unfrequently such evidence can be collected or appreciated only by means of a medico-legal inquiry.

1 and 2. On the first two articles, suspicious conduct or conversation on the part of the prisoner before the crime, and the possession or purchase of poison by him, little or nothing need be said. The medical witness may of course be asked whether the conduct or conversation proved betokens an unusual acquaintance with poisons and their effects. And his opinion may be referred to regarding the nature of suspected articles found in the prisoner’s possession. As to the purchase of arsenic under the false pretence of poisoning rats, it may be observed, that a great deal more stress is usually laid on such evidence than it seems to deserve; for there are few houses, in the country particularly, which are not more or less infected by them. On the other hand, too little weight is attached to the circumstance of the purchaser not having warned his household of poison being laid. Such conduct ought in my opinion to be accounted extremely suspicious; for so far as I have remarked, the fear with which unprofessional persons regard the common poisons is such, that I can hardly believe any master of a house would actually lay poison without warning the servants and other inmates of his having done so.

3. The next article, which relates to the proof of the administration of poison, will require some details.

Direct proof of the administration of poison by the actual giver is very rarely attainable, that part of the transaction being for the most part easily concealed. The proof of this point is justly accounted, however, a very important part of the evidence; nay, on some recent trials in this country the prosecution has failed apparently for want of such evidence, although the case was complete in every other particular. It is generally constituted by a chain of circumstances, and these are often strictly medical, as will now be shown by a few examples.

In the first place, pointed evidence as to the individual who gave the poison may be derived from the chemical investigation,—for example, from the comparative results of the analysis of the poisoned dish, and of the articles of which it consisted. I am indebted to my colleague, Dr. Alison, for the following excellent illustration from the case of William Muir, who was condemned at Glasgow in 1812 for poisoning his wife. In the course of the day on which she took ill she was visited by a farmer of the neighbourhood, who had studied physic a little in his youth. He learned from her that she had breakfasted on porridge a short time before she felt herself ill, and that she suspected the porridge to have been poisoned. He immediately procured the wooden bowl or cap in which the cottagers of Scotland keep the portion of meal used each time for making the porridge; and finding in it some meal, with shining particles interspersed, he wrapped a sample in paper, and took the proper measures for preserving its identity. He then secured also a sample from the family store in a barrel. The two particles were produced by him on the trial; and from experiments made in court the late Dr. Cleghorn was enabled to declare, that the meal from the bowl contained arsenic, and that the meal from the barrel did not. These facts, besides proving that the woman had next to a certainty taken arsenic in the porridge, likewise, in conjunction with other slight moral circumstances, established that the poison had been mixed with the meal in the house, and on the morning when the deceased took ill, before any stranger entered the house. The procedure of this farmer was precisely that which ought to be followed by the medical practitioner in a similar conjuncture.

An instance of an opposite description related by M. Barruel also deserves notice, as showing how evidence of this kind may afford, in otherwise suspicious circumstances, a strong presumption of accidental poisoning. Sixteen people near Bressières in France having been severely affected with vomiting and colic immediately after dinner, the bread, which was suspected, was examined by Barruel, and found to contain a little arsenic. The flour of which the bread was made had been taken from a large store of it, which, on being examined, was also found to be similarly impregnated. As it was extremely improbable that any one either could or would poison so large a mass of flour, to attain any malicious object, it was inferred that the arsenic had been mixed with it accidentally, and that the accident might have arisen from grain having been taken by mistake to the flour-mill to be ground, which had been intended originally for seed, and sprinkled with arsenic to destroy insects.[^[121]]

It may be worth while observing, in the present place, that in the instance of poisoned wine very important evidence may be obtained by examining whether the wine with which the cork is impregnated contains any traces of the poison. This method of investigation occurred to me in a very singular case of poisoning with arsenic in champagne, which happened in a baronet’s family in Scotland. In this instance, however, such analysis was proved to be unnecessary; for the gentleman himself brought the bottle from his cellar, broke the wires and drew the cork, immediately before the wine was drunk.[^[122]]

All evidence of the like nature, though it is at present often procured from other sources, should, for obvious reasons, be invariably collected, if possible, with the aid of a medical person. If again a medical man is called to a patient evidently affected with suspicious symptoms, and finds himself obliged to declare such to be his opinion, his thoughts, as soon as he has given directions for the treatment, should be turned towards that part of the evidence, for the securing of which he is naturally looked to as the person best qualified by previous education and his opportunities at the moment. With this view, therefore, having ascertained in what articles it is possible for poison to have been administered, he should at once endeavour to secure the remains of the particular portion partaken of by his patient, as well of the general dish, if it is an article of food, and of the ingredients of which the dish was ostensibly made, not forgetting the salt with which it was seasoned. A case occurred some years ago in the north of Scotland, in which arsenic was administered in porridge by mixing it with the salt.

It is of great consequence, before proceeding to analyze such articles, for example suspected dishes,—to be particular in investigating every thing connected with the cooking, serving, and eating of them. By doing so, not only will the chemical analysis be facilitated, but likewise facts in it will be accounted for, which might otherwise prove embarrassing, and even lead to the drawing of false conclusions from the result of the analysis. This statement is very well exemplified by the following incident which occurred to myself. In 1827 a family in Portobello were poisoned by the maid-servant; and it was believed, that, for the sake of a trick, she had, while carrying to the oven the beef subsequently used at dinner, maliciously mixed with it tartar-emetic or some other poison. One-half of the beef having been preserved, and two persons of the family having been very severely affected, Dr. Turner and I, to whom the case was remitted, made little doubt that we should discover the poison by chemical analysis: but we did not. Being subsequently employed by the sheriff to inquire into the particulars, I found that the poison had been mixed with the gravy, which had been consumed almost to the last drop,—that the gravy had been poured over the beef,—that the upper half of the beef had been eaten,—and that the remainder which we analysed had been transferred upon a different plate from that on which it was served for dinner. These particulars accounted sufficiently for the poison not having been discovered.

Another mode in which the chemical part of the inquiry may contribute to discover the individual who administered the poison is by a comparative examination of the persons of the deceased and the accused. The following very pointed illustration has been published by MM. Ollivier and Chevallier of Paris.—A woman who lived on bad terms with her husband was found dead on a roadside the morning after having been seen drunk in his company in the neighbourhood. The mouth, throat, and gullet were proved by a careful analysis to be corroded with nitric acid, the stains and traces of which were also found on various parts of her dress, and on the hair, neck, and arms, but not on her hands, and not lower down the alimentary canal than the upper fourth of the gullet. Ollivier, suspecting from these appearances, that she had not taken the acid voluntarily, requested to see the husband; whereupon there were found on his coat, trousers, and hands, a great number of stains, which, like those on the deceased, were proved by chemical analysis to have been produced by nitric acid. Here it was scarcely possible to avoid inferring, that the man got these stains while endeavouring to force his intoxicated wife to take the poison Marks of nail scratches were also observed round the mouth and on the throat; whence it was reasonably inferred, that, having failed in his original plan, he had suffocated her with his hands.[^[123]]

While these illustrations are given of the conclusiveness of the chemical evidence in fixing the administration of poison on a particular individual, it is essential likewise to observe that the same kind of evidence may be at times equally conclusive of the innocence of a person unjustly suspected. This obvious and important application of a chemical inquiry is forcibly suggested by the following particulars of an incident related by M. Chevallier:—An individual was accused by a woman of having tried to poison her; and she represented that he had put the poison into her soup, while it stood from one day to another in an iron pot. On making a careful analysis of some of the soup which remained, Chevallier found it so strongly impregnated with copper, that, supposing the sulphate was the salt mixed with the soup, ten ounces must have contained twenty-two grains. It then occurred to him, that it was important to examine the iron pot, in which the poisoned soup was represented to have been kept; for the probability was that a large quantity of the copper, if any salt of that metal had really been contained in the soup, would have been thrown down by the superior affinity of the iron, and consequently that a coppery lining would be found on the inside. He was led, however, to anticipate that no copper would be found there, because there was no iron dissolved in the soup, as would have been the case if copper had been precipitated from it by the iron of the pot. And accordingly he not only found no copper lining the inside of the pot; but likewise, on following the process described by the accuser as the one pursued in cooking the soup and in subsequently poisoning it, he satisfied himself by express trial that there was nothing in the circumstances of the case which could have prevented the iron from exerting its usual action on the salts of copper. These conclusions, coupled with certain facts of general evidence, proved substantially that the suspected person had nothing to do with the crime charged against him; and he was therefore discharged.[^[124]] A case somewhat similar will be related under the head of Imputed Poisoning.

In the second place, evidence as to the person who administered the poison may be procured by considering the commencement of the symptoms, in relation to the time at which particular articles have been given in a suspicious manner by a particular individual. The import of facts of this nature can be properly appreciated only by the medical witness; for he alone can be acknowledged as conversant with the symptoms which poisons produce, the intervals within which they begin to operate, and the circumstances in which their operation may be put off or accelerated.

Few cases will occur in which it is not possible to procure evidence of the kind, when diligently sought for. It is often too very decisive in its operation on judicial proceedings. In the case of Margaret Wishart tried at the Perth Spring Circuit in 1827 for poisoning her blind sister, a man who lodged with the prisoner and cohabited both with her and with the deceased, appeared at first from general circumstances to be implicated in the crime. He had left the house, however, on the morning of the day before that on the evening of which the deceased took ill; and he did not return till after her death. Now her illness commenced suddenly and violently; and arsenic was the poison which caused it.[^[125]] It was quite clear, therefore, that the poison could not have been administered, at least in a dangerous dose, so early as the day before she was taken ill; and such I stated to be my opinion, on a reference from the Lord Advocate. The evidence being also otherwise insufficient, the man was set at liberty. In the case of Mrs. Smith tried here in February of the same year, this branch of the evidence was made the subject of question under more doubtful circumstances. The deceased certainly died of poisoning with arsenic, and the prisoner was strongly suspected of being the poisoner for many reasons, and among others because, on the evening before the morning on which the deceased took ill, the prisoner gave her in a suspicious manner a white-coloured draught. Here the possibility of the draught having been the cause of the symptoms must be admitted. But as they did not appear for eight hours after the draught was taken, I stated in my evidence that it was improbable the dose, if it contained arsenic at all, contained a quantity sufficient to cause the violent symptoms and death which followed.[^[126]]

The correspondence in point of time between the appearance of symptoms of poisoning, and the administration of suspicious articles by an individual, constitutes still more decisive proof in a set of cases, in which it is of great value, as the chemical evidence is generally defective,—namely, where poisoning is attempted with repeated moderate doses. If the several renewals or exacerbations of illness correspond with the periods when suspicious articles have been given by the same individual, the circumstantial evidence of the administration may be even tantamount to direct proof. Thus, on the trial of Miss Blandy for the murder of her father, it was proved, that Mr. Blandy on several occasions, after the prisoner received certain suspicious powders from her lover, was taken ill with vomiting and purging; and that on two occasions recently before his death, when he got from his daughter a bowl of gruel which contained a gritty sediment, he was attacked after a very short interval with pricking and heat in the throat, mouth, stomach, and bowels,—with sickness, vomiting, gripes, and bloody diarrhœa.[^[127]] Here the proof of administration by the prisoner was complete.

These examples will show how the evidence of a particular person’s criminality may be affected by the relation subsisting in point of time between the commencement of the symptoms and the suspicious administration of particular articles. But farther, the special period at which the symptoms begin may even at times supply strong evidence of his instrumentality, although there may be no direct proof from general evidence of his having been concerned in administering anything whatever in a suspicious manner. This statement is well exemplified by the case of Mrs. Humphreys, who was convicted at the Aberdeen Autumn Circuit in 1830 for poisoning her husband, by pouring sulphuric acid down his throat while he was asleep. It was clearly proved, as will be seen under the head of sulphuric acid, that the deceased died of this poison; and the administration was brought home to the prisoner in the following singular manner. The only inmates of the house were the deceased, the prisoner, and a maid-servant. The deceased got a little intoxicated one evening at a drinking party in his own house; and after his friends all left the house, and the street-door was barred inside, he went to bed in perfect health, and soon fell fast asleep. But he had slept scarcely twenty minutes, when he suddenly awoke with violent burning in his throat and stomach; and he expired in great agony towards the close of the second day. Now sulphuric acid, when it occasions the violent symptoms observed in this instance, invariably excites them in a few seconds, or in the very act of swallowing. It was, therefore, impossible that the man could have received the poison at the time he was drinking with his friends; and as he knew he had not taken any thing else afterwards, and it was fully proved that he had been asleep before his illness suddenly began,—it followed that the acid must have been administered after he fell asleep, the accomplishment of which was rendered easy by a practice he had of sleeping on his back with his mouth wide open. But, after he gave the alarm, the door was found barred as when he went to bed. Consequently no one could have administered the poison except his wife or servant; and it was satisfactorily proved, that no suspicion could attach to the latter. Such was one of the principal train of circumstances, which, as it were by a process of elimination, led to the inference that the wife was undoubtedly the person who administered the poison. Other circumstances of a similar tendency were also derived from the medical evidence; but these it is unnecessary to detail at present. I have related the particulars of the whole case fully elsewhere.[^[128]] The prisoner strenuously denied her guilt after being sentenced, but confessed before her execution.

4. The next article in the moral evidence relates to the intent of the person who is proved to have administered poison. When the administration is proved, little evidence is in general required to establish the intent. It is sufficient that the giver knew the substance administered was of a deadly nature; and in regard to any of the common poisons this knowledge is sufficiently constituted by his simply knowing its name.

In some cases, however, the exact nature of the poison is not established with certainty; and then something else may be required to prove the prisoner’s knowledge, and through that knowledge his intent. In the case of Charles Munn, formerly alluded to [p. [50]], arsenic was the poison presumed to have been taken by the deceased. But the purchase or possession of it by the prisoner was not for some time satisfactorily established; neither was there any chemical evidence, the deceased having lived forty days and upwards after taking the poison. It was proved, however, that whatever it was which had been administered, the prisoner knew very well that what he gave was deleterious; because he persuaded the deceased, who was pregnant by him, to take it by assigning to it properties which no drug either possesses, or is so much as thought by the vulgar to possess. On one occasion he persuaded her that it would show whether she was with child, and on another that it would prevent people from knowing she was with child. In such cases, then, good evidence may be derived from the arguments used by the giver to persuade his victim to take the poison; and sometimes, as in the instance now mentioned, it will lie with the medical witness to inform the court whether or not the reasons assigned are false.

Sometimes it has been pleaded by the prisoner that he gave the poison by mistake. In all such cases, if he descends to particulars, which he cannot help doing, there is every likelihood that the falsehood of the defence will be made evident by the particulars of the story not agreeing with other particulars of the moral or medical evidence. At present it is only necessary to allude to inconsistencies in his story with the medical facts. No general rules can be laid down on the method of investigating a case with a view to evidence of this kind: I must be satisfied with an illustration from an actual occurrence. On the trial of Mr. Hodgson, a surgeon, at the Durham Autumn Assizes in 1824, for attempting to poison his wife, it was clearly proved, that pills containing corrosive sublimate, and compounded by the prisoner, were given by him to her in place of pills of calomel and opium, which had been ordered by her physician. But it was pleaded by him, that, being at the time intoxicated, he had mistaken, for the shop-bottle which contained opium, the corrosive-sublimate bottle which stood next it. This was certainly an improbable error, considering the opium was in powder, and the sublimate in crystals. But it was not the only one which he alleged he had committed. Not long after his wife took ill, the physician sent the prisoner to the shop to prepare for her a laudanum draught, with water for the menstruum. When the prisoner returned with it, the physician, in consequence of observing it to be muddy, was led to taste it, before he gave it to the sick lady: and finding it had the taste of corrosive sublimate, he preserved it, analyzed it, and discovered that it did contain that poison. The prisoner stated in defence, that he had a second time committed a mistake, and instead of water had accidentally used for the menstruum a corrosive-sublimate injection, which he had previously prepared for a sailor. This was proved to have been impossible; for the injection contained only five grains to the ounce, while the draught, which did not exceed one ounce, contained fourteen grains.[^[129]]

I believe it must be allowed, that, as the medical inquiries preparatory to trial are commonly conducted without the inspector being made acquainted with the moral circumstances in detail, it is rarely possible for him to foresee what points should be attended to, with the view of illustrating the intent. But the case now related will show that it is impossible for him to render his inquiries too minute or comprehensive; and more particularly, it shows the propriety of ascertaining, whenever it is possible, not only the nature but likewise the quantity of the poison.

5. The next article among the moral circumstances,—the simultaneous illness of other members of the family besides the person chiefly affected,—depends for its conclusiveness almost entirely upon the researches and opinion of the medical witnesses.

The fact, that several persons, who partook of the same dish or other article, have been seized about the same time with the same symptoms, will furnish very strong evidence of general poisoning. A few diseases, such as those which arise from infection or from atmospheric miasmata, may affect several persons of a family about the same time; and hysteria, and epilepsy, have been communicated to several people in rapid succession.[^[130]] But I am not aware, that, among the diseases which resemble well marked cases of poisoning either with irritants or with narcotics, any one ever originates in such a way as to render it possible for several persons in a family to be attacked simultaneously, except through the merest and therefore most improbable accident. Cholera perhaps is an exception. But when cholera attacks at one time several people living together, it arises from bad food, and is properly a variety of poisoning. In such cases, too, the fallacy may in general be easily got the better of, by finding that the store or stock, from which the various articles composing the injurious meal have been taken was of wholesome quality.

Hence it may be laid down as a general rule, that, perhaps if two, but certainly if three or more persons, after taking a suspected article of food or drink, are each affected with symptoms, furnishing of themselves presumptive evidence of poisoning, and have been seized nearly about the same time, and within the interval after eating within which poisons usually begin to act,—the proof of poisoning is decisive. Several late cases might, in my opinion, have been decided by this rule. Thus it might have decided the important case of George Thom tried at Aberdeen in 1821 for poisoning the Mitchells, and likewise that of Eliza Fenning, about whose condemnation some clamour was made in London in 1815. In both instances, as will be mentioned under the head of arsenic, the symptoms were developed so characteristically, that from them alone poisoning with arsenic might have been inferred almost to a certainty. But even if the symptoms had been somewhat less characteristic, all doubt of general poisoning was set aside by the fact, that four persons in the former case, and five in the latter, were similarly and simultaneously affected, and all of them at an interval after eating, which corresponded with the interval within which arsenic usually begins to act.

Sometimes it happens, that while one or more of a party at a certain meal suffer, others escape. Such an occurrence must not be hastily assumed as inconsistent with poison having been administered at that meal. For the guilty person may have slipped the poison into the portion taken by the individual or individuals affected.

If it be proved that all who ate of a particular dish have suffered, and all who did not have escaped, the kind of moral evidence now under review becomes strongest of all. It is well for the medical jurist to remember also, that such evidence is very useful in directing him where chiefly he should look for poison.

At other times it happens that the several people affected, suffer in proportion to the quantity taken by each of a particular dish. Too much importance ought not to be attached to the absence of that relation; for it has been already mentioned that habit, idiosyncrasy, and the state of fulness of the stomach at the time, will modify materially the action of poisons. But when present, it will often form strong evidence.—A good illustration of what is now said may be found in the case of Thomas Lenargan, tried in Ireland for the murder of his master, Mr. O’Flaherty. He had for some time carried on an amour with O’Flaherty’s wife; and afterwards, to get rid of the troublesome surveillance of the husband, contrived to despatch him by poison. The crime was not suspected for two years. Among the facts brought out on the trial the most pointed were, that O’Flaherty’s daughter and two servants were affected at the same time with the very same symptoms as himself; that they had partaken of the same dish with him; that the severity of their several complaints was in proportion to the quantity each had taken; and that others of the family, who did not eat it, were not affected.[^[131]]

Another remarkable instance of this kind has been recorded by Morgagni. A clergyman, while travelling in company with another gentleman and two ladies, was setting out one afternoon to resume his journey after dining at an inn, when he was suddenly taken ill with violent pain in the stomach and bowels, and soon after with vomiting and purging. One of the ladies was similarly affected, but in a less degree; and likewise the other gentleman, though in a degree still less: but the other lady did not suffer at all. Morgagni found, that this lady was the only one of the party who had not tasted a dish of soup at the commencement of dinner. But he was puzzled on finding that the gentleman who suffered least had taken the largest share of the soup, while the clergyman had taken less than either of the two that were seized along with him. He then remembered, however, that in the district where the accident happened, it was the custom to use scraped cheese with the soup in question; and on inquiry he was informed that they had each added to the soup a quantity of cheese proportioned to the severity of their illness. Here, therefore, Morgagni was led to suspect the presence of poison; and accordingly, after the whole party had fortunately recovered, the innkeeper acknowledged, that in the hurry of preparation, he had served up to his guests cheese seasoned with arsenic to poison rats.[^[132]] This interesting anecdote shows, that the truth in such cases is not always to be discovered without minute inquiry and considerable adroitness. In the case of poisoning with arsenic in wine formerly alluded to,—where all the individuals at table, to the amount of six, were severely affected during dinner,—the soup was the article suspected, because all had partaken of it; and, accordingly, the soup and vomited matter were sent to me for analysis. On detecting a trace of arsenic in the vomited matter, but none in the soup, I suggested that some other article might have been used in common by the party, and mentioned the wine as a probable article of the kind. It turned out that all had drunk a single glass of champagne from a particular bottle; and in the wine remaining in this bottle arsenic was found in the proportion of half a grain per ounce.[^[133]]

Cases of this nature are so instructive that no apology need be made for mentioning one example more which lately came under my own notice. In the case of Mary Anne Alcorn, convicted here in the summer of 1827, of having administered poison to her master and mistress (a case already referred to for another purpose, p. [75]), it was proved that a white powder was introduced in a suspicious manner into the gravy of baked beef, which gravy was subsequently poured over the beef. Now the master of the family dined heartily on beef, potatoes and rice-pudding, and mixed the greater part of the beef gravy with his pudding; the mistress ate moderately of the first slices of the beef, took very little gravy, even to the beef, and none at all to the pudding; a little girl, their niece, dined on pudding alone, without gravy; and the prisoner dined after the family on the beef and potatoes. Accordingly the master suffered so severely as for two or three days to be in danger of his life, the mistress was also severely, but by no means so violently affected, the little girl did not suffer at all, and the servant had merely slight pain and sickness at stomach. The evidence thus procured was exceedingly strong, more particularly when coupled with the fact, that the beef used was half of a piece, the other half of which had been used by the family two days before, without any ill consequences.

6. The next article of the moral evidence relates to suspicious conduct on the part of the prisoner during the illness of the person poisoned. Under this head it is necessary merely to state what I conceive to be, with reference to the present branch of the proof, the duty of the medical practitioner who happens to attend a case of poisoning.

In such a conjuncture he is undoubtedly placed in a situation of some delicacy. But on considering the matter attentively, good reasons will appear why he should adopt the course, which, I believe, our courts of justice will expect of him, and keep some watch over the actions of any individual who is suspected of having committed the crime. On the one hand, no one else is by education and opportunities so capable of remarking the motions of the different members of the family dispassionately, without officiousness, and without being observed. And on the other hand, it is undoubtedly a part of his private duty as practitioner, to protect his patient against any farther criminal attempts, as well as part of his public duty to prevent the vomited matter and other subjects of analysis from being secretly put away or destroyed. No one can be so occupied without many accessary particulars coming under his notice. And certain it is, that on several trials the practitioner has contributed, with great credit to himself, a considerable part of the pure moral proof. For an example of discreet and able conduct under these trying circumstances, the reader will do well to refer to that of Dr. Addington, the chief crown witness, both as to medical and moral facts, in the case of Miss Blandy.[^[134]] It is almost unnecessary to add, that in acting as now recommended, the physician must conduct himself with circumspection, in order to avoid giving unnecessary offence, or alarming the guilty person.

7, and 9. On the seventh article, which respects the conduct of the prisoner after the death of the deceased, and on the ninth, which relates to the existence of a motive or inducement to the crime, nothing need be said here. But on the

8th article of the moral evidence,—comprehending the death-bed declaration of the deceased, his state of mind, his personal circumstances and other points which prove the possibility or impossibility of voluntary poisoning—a few remarks are required, because an important and little understood part of the practitioner’s duty is connected with this branch of the proof.

The question as to the possibility of the poisoning being voluntary is one upon which the medical attendant will be expected to throw some light, and into which he will also naturally inquire for his own satisfaction. In doing so his attention will be turned to circumstances purely moral, which may not only decide that question, but may also criminate a particular individual. His inquiries must therefore be conducted with discretion, and for obvious reasons should be confined as much as possible to the patient himself. They are to be conducted not so much by putting questions, as by leading him to disburden his mind of his own accord; and it is well to be aware, that there is no one of whom a patient is so ready to make a confident on such an occasion as his medical attendant.

If disclosures of consequence are made, and the attendant should feel it his duty to look forward to the future judicial proceedings and to the probability of his appearing as a witness, he ought to remember the general rule is, that his account of what the patient told him is not evidence in the eye of the law, unless it was told under the consciousness of the approach of death. Of late, however, the rigour of this principle in law has been occasionally departed from in Scottish practice; and in regard to medical facts ascertained in the way here mentioned, many strong reasons might be assigned for such relaxation. Evidence of the kind is technically called the death-bed declaration of the deceased, and is justly accounted very important.

Here it is right to take notice of a part of the death-bed evidence, although it does not properly belong to the question of suicide, because it should always be collected if possible by the medical attendant, and with much greater care than is generally bestowed on it even by him—I mean the history of the symptoms previously to his being called in. On this part of the history, including particularly the time and manner in which the illness began, medical conclusions of extreme consequence are often subsequently founded: On a single fact or two may depend the fate of the prisoner. It is not enough, therefore, in my opinion, that such evidence formed a part of the death-bed declaration. If a fact derived at second hand from the deceased, and stated too by him from memory, is a material element of any of the medical opinions on the trial, it is of much importance that the information be procured by a medical man; and that the person who procured it, whether professional or not, was aware at the time of the probability of its becoming important. Such evidence, although not collected with these precautions, is admissible; but I have so often had occasion to witness the carelessness with which the previous history of cases is inquired into both in medical and medico-legal practice, that I do not see how it is possible to put trust in evidence of the kind, unless it bear marks of having been collected with care, and under an impression of its probable consequence. These statements are well illustrated by the following example:—On the trial of Mrs. Smith for poisoning her maid-servant with arsenic, it was proved that some drug was administered by the prisoner in a suspicious manner on a Tuesday evening. Now it appeared at the trial improbable that this drug contained a fatal dose of arsenic, because to her fellow-servants, of whom one slept with her, and others frequently visited her, the deceased did not appear to be ill at all for eight hours after, or seriously ill for nearly a day. On the contrary, however, a surgeon, who was called to see her on the following Saturday, a few hours before her death, deposed that, according to information communicated by herself, she had been ill with sickness, vomiting, purging, and pain in the stomach and bowels since the Tuesday evening. This evidence, if it could have been relied on, would have altered materially the features of the case, as it would have gone far to supply what all the medical witnesses considered defective, namely, proof of the administration. But at the time the surgeon made his inquiries, he did not even suspect that the girl laboured under the effects of poison. Neither he therefore nor his patient could have been impressed with that conviction of the importance of the information communicated, which was necessary to insure its accuracy, particularly as it related to a matter usually of so little consequence in ordinary medical practice as the precise date of the commencement of an illness; and it would consequently have been rash to adopt it in face of more direct and contrary evidence. Any one who examines the details of this trial as I have reported them, will at once see how much the case turned on the point now alluded to.[^[135]]

CHAPTER III.
OF IMAGINARY PRETENDED, AND IMPUTED POISONING.

The present seems the most convenient place for noticing the general mode of procedure by which the medical jurist may detect cases of imaginary, feigned, and imputed poisoning. It is by no means easy to lay down rules for the investigation of cases suspected to be of such a kind. But an attempt will be made to state the leading points to be attended to, and to illustrate them by the circumstances of a few examples of each variety.

Imaginary poisoning should rarely be the occasion of deception or embarrassment. The same wandering of the imagination which has led to a belief of injury from poison, will commonly also lead to such extravagant notions relative to the mode of administration and the symptoms, as will infallibly point out the true nature of the case to one who is well acquainted with the real effects of poisons. It is easy, nevertheless, to conceive cases which may be embarrassing; and certainly, in every instance, the physician should proceed in his inquiries with caution.

It appears to me that in the first place, without seeming to take up at once the conviction of his patient, he should scrupulously abstain from treating it lightly, and should on the whole act rather as if he suspected poison had been given. Allowing his patient therefore apparently credit for the truth of his suspicions, the medical attendant should request him to give a full history of existing symptoms, of their origin and progress, of their relation in point of time to various meals, and of the mode and vehicle in which the supposed poison was administered. No unprofessional person can possibly go through such a narrative, without stating many circumstances which are wholly irreconcilable with the idea of poisoning generally, and still more of the administration of a particular poison.

I have met with two instances of imaginary poisoning, the nature of which was thus at once made obvious by a host of impossibilities in the narrative of the patient. One of these may be here given as an example. An elderly lady, who had certain expectancies of the death of a relation, conceived that the family of her relative had resolved to defraud her of her supposed rights. She afterwards imagined that an attempt was made to poison her, and camphor was the poison she fixed on as the article which had been administered. In its general or moral particulars the narrative was all plausible and suspicious enough; but unluckily for its consistency, she stated that the poison could only have been given in wine,—that she did not remark any particular taste in the wine,—that her illness did not begin till the day after she took it; and although she alleged, without any leading question on my part, that camphorous perspiration was exhaled on the subsequent day, the whole train of symptoms differed entirely in every other respect from a case of poisoning, and resembled closely in their origin and progress a case of slight general fever. The incompatibility of her story with the idea of poisoning with camphor will be readily understood by referring to what is afterwards said of the effects of that substance.

Feigned or pretended poisoning is more apt to escape suspicion, and when suspected is commonly more difficult to develope satisfactorily; for the actor has it in his power to lay his plans with care, and even to become acquainted with the properties of the poisons whose effects he intends to feign. Still he can rarely enact his part so well as to deceive a skilful physician both by existing symptoms and by his history of their origin and progress; much less can he contrive his scheme so adroitly that it shall not be unfolded by the refinements of chemical analysis.

The investigation of such a case will be directed of course in the first instance to the state and progress of the symptoms. Here, as in imaginary poisoning, it is of moment to conceal from the individual the suspicion entertained of his falsehood. For even if a person who has actually taken poison knows he is unjustly suspected of feigning, it is not improbable that he might try to mend his story with impossibilities, and so lead the physician into error. In a case of feigned poisoning an excellent mode of investigation is, after hearing out the individual’s own story, to put a number of questions involving an alternative answer, one alternative being compatible and the other incompatible with the alleged nature of his illness. No unprofessional person can stand such a system of interrogation, if skilfully pursued. Not only will his answers be often wrong; but likewise his manifest perplexity how to answer will of itself supply evidence of falsehood.

In the next place, great attention must be paid to the chemical analysis. A person who feigns poisoning will commonly produce the poisoned remains of a dish, or some other article, which he represents himself to have swallowed. Sometimes the substance contained in it will prove on analysis not to be poison at all, as in an instance I remember reading some years ago in a London newspaper of pretended poisoning with arsenic, where the dregs of a bowl of gruel contained, not arsenic, but finely pounded glass. Sometimes the quantity of a real poison contained in the remains of a dish may indicate, in what is said to have been swallowed, a portion wholly incompatible with the mildness or severity of the symptoms. Sometimes the vomited matter, even the matter first vomited, may not contain any of the alleged poison. Sometimes poison found in matter alleged to have been vomited may yield compounds during analysis which are not animalized, showing that it never was in the stomach. Sometimes the quantity of poison contained in such matter may be greater than that alleged to have been taken. Sometimes the quantity contained in the first matter vomited may be less than that contained in what is vomited or said to be vomited subsequently. By these and many other such inconsistencies the falsehood of the story may be unequivocally unfolded.

The following example will illustrate some of the rules now laid down. A young married female, in the seventh month of pregnancy, having been discovered by her friends to be secretly addicted to dram-drinking, appeared to be much annoyed in consequence of the discovery; and one evening was found apparently very ill by her husband on his return from work. She represented that she had taken arsenic with a view to self-destruction, that she was in great torture, and that she was sure she must soon die. It was accordingly found, on reference to a neighbouring apothecary, that she had the same forenoon purchased about a drachm and a half of arsenic for the pretended purpose of poisoning rats; and in the bottom of a teacup, in which she said she mixed it, there was left a small quantity of white powder, that proved on analysis to be pure oxide of arsenic. Notwithstanding these strong facts, the mildness of the symptoms and the composure with which she complained of her tortures led her friends to suspect she was feigning. On investigating her case I first ascertained, in farther corroboration of her story, that the powder was nowhere to be found. But she then stated in reply to questions involving an alternative answer, that the arsenic had a sour taste, and that the pain began in the lower part of the belly, and spread upwards. She likewise said that she vomited a mouthful or two into a chamber-pot twenty minutes after taking the poison; that she vomited no more till the apothecary was sent for, who gave her emetics of sulphate of zinc, carefully preserving the discharges; and that she only vomited when emetics were given. When I first saw her, five hours after the alleged date of the taking of the arsenic, the skin was warm and moist, the face full and flushed, the pulse frequent and firm, the muscular strength natural. The chamber-pot contained only a small quantity of the fæces of a child and apparently a little water, but no vomited matters, and no white powder. The fluid discharged in presence of the apothecary was found on careful analysis to contain a large quantity of zinc, but not an atom of arsenic. She gradually recovered from the illness under which she laboured at the time I saw her, and in two days she admitted she was quite well, but continued to insist that she had taken the poison.—M. Tartra has related a singular case of the same kind, where a young woman feigned poisoning with nitric acid, and was not detected for several days.[^[136]]

Imputed poisoning differs in general from feigned poisoning only in so far as the symptoms which are feigned are imputed to the agency of another.

The imputation of the crime of poisoning by feigning or actually producing the symptoms, and contriving that poison shall be detected in the quarters where in actual cases it is usually sought for, has been not unfrequently attempted. Two important continental cases have already been referred to for other purposes [pp. [66], [76]]; and I may here relate the heads of two English cases, which are of great interest, and will serve to illustrate the mode of procedure in such circumstances.

The first of these, which I have related elsewhere in detail,[^[137]] is a striking example of the power of science in eliciting the truth, and redounds highly to the credit of Mr. Thackrah, the medical gentleman who conducted the investigation.

Samuel Whalley was indicted at York Spring Assizes in 1821, for maliciously administering arsenic to Martha King, who was pregnant by him. The woman King swore, that the prisoner, after twice trying, but in vain, to prevail on her to take drugs for the purpose of procuring abortion, sent her a present of tarts, of which she ate one and a half,—that in half an hour she was seized with symptoms of poisoning with some irritant poison,—and that she continued ill for a long time after. Mr. Thackrah found arsenic in the tarts that remained untouched, and likewise in some matter that was vomited in his presence after the administration of an emetic, as well as in other vomited matters which were preserved for him between his first and second visits. Her appearance, however, did not correspond with the complaint she made of her sufferings, her pulse and tongue were natural, and on careful investigation the following inconsistencies were farther detected. 1. She said she felt a coppery taste in the act of eating the tarts, a taste which arsenic certainly does not possess. 2. From the quantity of arsenic in the tarts which remained she could not have taken above ten grains, while even after repeated attacks of vomiting, the alleged matter subsequently preserved contained nearly fifteen grains. 3. The matter first vomited contained only one grain, while the matter alleged to have been vomited subsequently contained fifteen grains. 4. The time at which these fifteen grains were alleged to have been vomited was not till between two and three hours after the symptoms began; in which case the symptoms would before that time have been in all probability violent. The prisoner was acquitted, and the prosecutor and another woman who corroborated her deposition afterwards confessed that they had entered into a conspiracy to impute the crime to him, because he had deserted her on finding she was too intimate with other men.

Another case not less interesting in its details was communicated to me by my colleague Dr. Traill, who was consulted by the medical attendant, Mr. Parr of Liverpool. A man accused his sister-in-law of administering poison in his tea. He stated that he was seized with pain in the stomach and uneasiness in the head half an hour after taking the tea; and when visited soon after, the countenance was anxious, the skin pallid, the pulse frequent, the throat red; and while Mr. Parr was examining the throat, a quantity of matter was vomited, containing a white, gritty, crystalline substance, which was afterwards ascertained to be oxalic acid. The following circumstances, however, proved that the poison could not have been given in the tea. The man alleged that he remarked in the very first mouthful an acrid taste, followed by sweetness, which is not the taste of oxalic acid. Notwithstanding this warning, he drank the greater part of the tea. He stated that the poison was dissolved in the tea, yet he vomited some oxalic acid in the solid form. Granting he was mistaken in supposing the whole poison dissolved, the quantity swallowed must in that case have been large; and nevertheless the symptoms were mild, though no vomiting took place for about an hour, and next day he was almost well. Four other individuals had tea at the same time from the same tea-pot, without sustaining any harm; and what remained of the infusion did not contain any oxalic acid. Finally, his niece took what he left of his tea in the cup, without remarking any unusual taste; and in the unwashed cup not a trace of oxalic acid could be detected. It was quite plain, therefore, that the man’s accusation was false; and certain points of general evidence, coupled with the medical facts, afterwards proved that he must have taken the oxalic acid himself.

It has been alleged, that attempts have been made to impute the crime of poisoning by introducing poisonous substances into the body after death; and although I have not been able to find any actual instance of such ingenious atrocity mentioned by authors, it must be acknowledged to be quite possible; and the medical jurist should therefore be prepared for the requisite investigations. Every case may be clearly made out by attending to the relative effects of poisons on the dead and on the living tissues;—a subject which will receive some notice under the head of the principal poisons in common use.

PART SECOND.
OF INDIVIDUAL POISONS.

CHAPTER I.
OF THE CLASSIFICATION OF POISONS.

After the preliminary observations on General Poisoning, I proceed next to treat of Poisons Individually. The subsequent remarks will be confined in a great measure to the most common poisons, which will be examined minutely. The rest being mere objects of curiosity, and hardly ever taken by man either intentionally or by accident, it will be sufficient to point out their leading properties.

It may be well to point out in the first instance the poisons in most general use. These will appear from the following Tables. The first is compiled from a Parliamentary Return of the cases of fatal poisoning brought before the coroners of England in two years ending with 1838.

In France, in seven years, from 1825 to 1831, inclusive, there were 216 trials for poisoning, at which 273 persons were charged with the crime, and only 102 condemned. In 94 cases occurring between November 1825 and October 1832, the substances employed were as follows.[^[138]]

In the subsequent seven years there were 218 trials, and 153 prisoners condemned. Among 194 of these the following were the poisons used.[^[139]]

In Denmark, in five years ending with 1835, there were 99 cases of poisoning of all sorts, 16 by arsenic, 74 by sulphuric or nitric acid, 4 by potash, 1 by an unascertained caustic substance, 2 by opium, 1 by litharge, and 1 by copper. Only 5 cases, namely, 3 by arsenic and 2 by sulphuric acid, were cases of murder, or attempt to murder.[^[140]]

The classification of poisons has hitherto defied the ingenuity of toxicologists. Formerly it was thought sufficient to arrange them in three great classes, according as they are derived from the mineral, the vegetable, or the animal kingdom. It is evident, however, that the only sound basis of arrangement is their action on the animal economy; for such a classification is the only one which can be useful in practice. Now, when we consider what has been said on their mode of action, or the symptoms produced in consequence of that action, it must at once be perceived, that no system founded on either of these circumstances can be logically correct. It would be very desirable, if their mode of action could be adopted as the basis of arrangement; but both reasoning and experience have proved this to be impracticable. One very distinct class indeed might be formed of purely local poisons, comprehending the mineral acids, the fixed alkalies, and one or two of their chemical compounds. But a vast proportion of the other poisons which act locally have also a general or remote action; and on the other hand there are few of the latter description which do not likewise act locally. Hence if all which possess this double action were arranged in one class, that class would include nine-tenths at least of known poisons; so that, in truth, the labour of classification would still remain to be overcome.

It would be even more fruitless to attempt an arrangement of poisons according to their medium of action; for no sure criterion is known, by which a poison acting through direct transmission of an impulse along the nerves can be distinguished from one that acts by entering the blood.

Neither is the embarrassment of the toxicologist materially less, if he attempts to classify poisons according to the symptoms they induce in man. This is the principle now generally followed, and which in common with others I shall pursue. But the reader will be at no loss to discover that the partitions which separate the classes are exceedingly slight, and that very many poisons might be arranged without impropriety in either of two classes.

The preceding statements show the impossibility of founding a good system of arrangement on the only basis which can be acknowledged philosophical and practical; and consequently, that, as the science of toxicology now stands, we must altogether despair of forming one that shall be even moderately satisfactory.

On the whole I see no reason for deviating from the classification adopted in the first edition of the present work, being a modification of that previously followed by Professor Orfila. In this classification poisons are divided into irritants, narcotics, and narcotic-acrids.

The class of irritants includes all poisons whose sole or predominating symptoms are those of irritation or inflammation; the narcotics those which produce stupor, delirium, spasms, paralysis, and other affections of the brain and nervous system; and the narcotico-acrids those which cause sometimes irritation, sometimes narcotism, sometimes both together. Some writers still adopt a fourth class, called septics, because they give rise to putrefaction in the living body. But modern physiology will scarcely sanction the continuance of such a class of poisons. For assuredly no substance can cause putrefaction in the living body.

CHAPTER II.
CLASS FIRST.
ON IRRITANT POISONS GENERALLY.

The class of irritant poisons comprehends all whose sole or predominant action consists in exciting irritation or inflammation. That is, it comprises both those which have a purely local, irritating action, and likewise many which also act remotely, but whose most prominent feature of action still is the inflammation they excite wherever they are applied.

This subject will be introduced with an account of the general symptoms and morbid appearances caused by the irritants, and a comparison of these with the symptoms and morbid appearances of the natural diseases which are chiefly liable to be confounded with irritant poisoning, or mistaken for it.

Section I.—Of the Symptoms of the Irritant Poisons, compared with those of natural diseases.

The symptoms caused by the irritating poisons, taken internally, are chiefly those of violent irritation and inflammation of one or more divisions of the alimentary canal.

The mouth is frequently affected, especially when the poison is easily soluble, and possesses a corrosive as well as irritating power. The symptoms referrible to the mouth are pricking or burning of the tongue, and redness, swelling and ulceration of the tongue, palate, and inside of the cheeks.

The throat and gullet are still more frequently affected; and the affection is commonly burning pain, sometimes accompanied with constriction and difficulty in swallowing, and always with redness of the visible part of the throat and gullet.

The affection of the throat and mouth precedes every other symptom when the poison is an active corrosive, and more particularly when it is either a fluid poison or is easily dissolved. Nay, sometimes burning pain of the mouth, throat, and gullet occurs during the very act of swallowing.—On the contrary if the poison is soluble with difficulty, and is only an irritant, not a corrosive, and still more if it is only one of the feebler irritants, the throat is frequently not affected sooner than the stomach, occasionally not at all.

The stomach is the organ which suffers most invariably from the operation of irritant poisons. The symptoms referrible to their operation on it are acute and general burning pain, sometimes lancinating or pricking pain,—sickness, vomiting, tenderness on pressure, tension in the upper part of the belly, and occasionally swelling. Of these symptoms the sickness is generally the first to develope itself. In the instance of corrosive irritants pain commonly commences along with it. The matter vomited is at first the contents of the stomach, afterwards tough mucus, streaked often with blood and mingled with bile, frequently clots of purer blood. The powerful corrosives affect the stomach the moment they are swallowed; irritants which are either liquid or very soluble also affect it very soon; but the more insoluble irritants, such as arsenic, generally do not begin to act till half an hour or even more than a whole hour has elapsed.—The stomach may be affected without any other part of the alimentary canal participating in the injury; but much more frequently other parts suffer also, and in particular the intestines.

The action of irritant poisons on the intestines is marked by pain extending over the whole belly, sometimes even to the anus. This pain, like that of the stomach, is often a sense of burning; but it is also frequently a pricking or tearing pain, and still more frequently a twisting, intermitting pain like that of colic. It is seldom attended with much swelling, but often with tension, and tenderness of the whole belly; and at times the inflammatory state of the mucous coat of the intestines is clearly indicated by excoriation of the anus and prolapsus of the rectum, which is of a bright red colour. The pain of the bowels is most generally attended by purging, rarely with constipation, frequently with tenesmus. The matter discharged, after the alimentary and feculent contents have passed, is chiefly a mucous fluid, often abundant, often also streaked with blood or mixed with considerable quantities of blood. In some cases the intestines are affected when no other part of the alimentary canal suffers, not even the stomach. But much more generally the stomach and intestines are affected together.

In a few very aggravated cases of poisoning with the irritants the whole course of the alimentary canal, from the throat to the anus, is affected at one and the same time.

The symptoms now briefly enumerated are accompanied in almost every instance with great disturbance of the circulation—quick, feeble pulse—excessive prostration of strength,—coldness, and clammy moisture of the skin.

The other symptoms, which are often united with the preceding, do not belong to the irritants as a class. Perhaps, however, among the symptoms of the class may be mentioned those of irritation and inflammation of the windpipe and lungs, and those of irritation in the urinary organs. A great number of the irritant poisons cause hoarseness, wheezing respiration, and other signs which indicate the spreading of the inflammation of the throat to the windpipe: some likewise cause darting pains throughout the chest: and not a few are very apt to cause strangury and other signs of inflammation of the urinary passages.

Of the effects of the irritants when applied externally little need be said at present. Their most striking external symptoms will be noticed under the head of one of the orders of this class, the vegetable acrids. In the chapter on the local action of poisons some account was given of the several effects which are produced by the application of poisons to the skin. It is there stated that some produce merely redness, that others cause blistering, that others bring out a crop of deep-seated pustules, that others corrode the tissues chemically, and so give origin to a deep slough, and that others excite spreading inflammation of the cellular tissue under the skin and between the muscles.