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.