In this part of his work M. Orfila has completely failed, and we believe it is impossible to succeed in it. The action of each poison is so exceedingly various, according to the circumstances under which it is exhibited, and the state of the system on which it acts, that it seldom admits of being generalized; but a general description of the effects and treatment of corrosive poisons, under which denomination are included many substances, having very little analogy in their action, and some acting upon totally different principles, must either be so vague as to convey no information, or must consist of an assemblage of errors.

In treating of the individual poisons, M. Orfila speaks in succession of their chemical and physical properties-their physiological action-the general symptoms they produce, illustrated by cases-the organic lesions they produce-the application of the preceding facts to the different cases which may occur in medico-juridical practice, and the manner of counteracting their effects, with an inquiry into their alleged antidotes.

The facts relating to the physical and chemical history of each poison are well chosen, and perspicuously narrated and explained; but we were particularly pleased with finding an accurate account of their habitudes, with many vegetable and animal matters, for which the best systematic works on chemistry will be consulted in vain, although their knowledge is of the greatest importance to the juridical physician. Every chemical writer describes the manner of detecting the usual mineral poisons, and their action upon various reagents; but their description is taken from experiments made upon the substance in a simple state, or dissolved in water. In juridical practice the circumstances are totally different. The substance and its quantity are not only unknown, but it is almost always mixed with other substances, which suspend or alter the common effects of reagents upon it; so that our knowledge of pure chemistry may sometimes mislead us. The perusal of M. Orfila's work cannot fail of convincing every physician of the necessity of studying the objects of juridical chemistry more minutely than the general chemist will ever condescend to do.

Corrosive sublimate is decomposed, sooner or later, and con

verted into the submuriate, by almost all vegetable substances, distilled waters, extracts, oils, syrups, honeys, gums, and alkohol. Its action upon albumen is so marked, that it has been proposed by Dr. Bostock as the most delicate test of that animal oxide; but in sufficient quantity it also coagulates milk, and causes a precipitate with gelatine, and in beef-tea. It is precipitated red by osmazome, and orange by bile; and it acts remarkably on fibrine or flesh, corrugating and hardening it. But the manner in which the presence of these substances alters the action of the reagents or tests is still more worthy of notice. The precipitate obtained from mixtures of corrosive sublimate, with boiled beans and broth, or albumen, vegetable broth, boiled apples, tea and sugar, was not blackened by lying in lime-water for two days, (p. 83, Vol. I.) yet yielded mercury by sublimation. Dissolved in Burgundy wine, it was precipitated black by potass, very dark green by ammonia, blue, passing to violet by prussiate of potass, and syrup of violets was changed by it to green. Dissolved in beef-tea, it is precipitated white, or gray or black by potass, and dirty white or yellowish by lime-water, and the addition of bile to a solution of corrosive sublimate prevented it from being affected by ammonia or potass.

In regard to arsenic, the necessity of being able to detect it, when disguised by the presence of other matters, is more obvious, as it does not discover itself by its taste, and is therefore more likely to be employed for committing murder than any other mineral poison. Solutions of albumen, or gelatine, and common beef-tea, and bile, were not affected by the addition of arsenic, and did not affect considerably the action of the common reagents. Strong tea, however, completely altered them; so that nitrate of silver gave a yellowish white precipitate, which became instantly black, lime-water a dirty canary yellow, and sulphate of copper a reddish violet; sulphuretted hydrogen alone furnished its usual yellow precipitate. Decoction of coffee with arsenic was precipitated of a deep yellow by nitrate of silver, of a grass green by ammonia-sulphate of copper, of a golden yellow by sulphuretted hydrogen, and yellow by lime-water. Wine with arsenic gave deep yellow by sulphuretted hydrogen, bluish-black by ammonia-sulphate of cop

per, and white by nitrate of silver: with a larger proportion of arsenic, the copper yielded a green precipitate. Arsenic mixed with milk was also difficult to detect. All these mixtures, evaporated to dryness, and treated with distilled water, indicated the presence of arsenic, by one or other of these tests; and from all of them, metallic arsenic was obtained, by reduction with potass and charcoal. These are all the facts of this nature in regard to arsenic given by M. Orfila, but they are far from being sufficient; and we regret that want of room obliges us to postpone many corrections and additions which our experience could afford.

Tartar emetic gives an orange precipitate, containing oxide of antimony, when mixed with vegetable juices and decoctions. The tincture of gall-nuts is its most delicate test, and furnishes a copious curdy dirty yellow precipitate. One part of a saturated solution of tartar emetic, mixed with ten of red wine, remains transparent, but the mixture yields a reddish yellow precipitate, on the addition of some drops of hydrosulphuret of ammonia, or hydrosulphuretted water, and becomes green on the addition of a larger quantity of the reagent; with tincture of galls the precipitate is clear violet, and with sulphuric acid deep violet. One part of the solution, with ten of strong tea, remains transparent, but the mixture is precipitated deep red by hydrosulphuret of ammonia, and yellowish-white by sulphuric acid; but is merely rendered turbid by tincture of galls. Albuminous or gelatinous fluids or bile do not seem to alter the effects of the reagents in this case.

A solution of nitrate of copper is precipitated of a reddish yellow by tea. When mixed with red wine, in the proportion of one to ten, it remains transparent, but the mixture is precipitated black by the hydrosulphurets, marron brown by the precipitate of potass, and very dark gray by ammonia, which does not redissolve the precipitate entirely, and never gives a blue colour to the fluid. Acetate of copper forms a coagulum in albuminous fluids and milk, and it seems to be rendered insoluble in water by being triturated with sugar.

Muriate of tin decomposes almost all animal and vegetable fluids, except simple syrup.

Sulphate of zinc in solution is not affected by syrup or Bur

gundy wine, but is precipitated deep blue by tea and galls, white by albumen and gelatine, yellow by bile, and curdles milk.

Nitrate of silver in solution is not affected by tincture of gallnuts or gelatine; but it changes the colour of tea to red and black, and precipitates albumen, gelatine, milk, and bile. Mixed with Burgundy, it is precipitated of a violet colour instead of yellow, by phosphat of soda.

Muriate of gold in solution is not affected by syrup; is precipitated reddish yellow by tea; red, chocolate, or metallic, by tincture of galls; deep purple and metallic, by Burgundy; yellowish, by albumen and gelatine; green, passing to purple and violet, by bile; and curdles milk.

Nitrate of bismuth is not affected by gelatine; is precipitated yellowish white by tincture of galls and strong tea; yellow, by bile, and coagulates albumen and milk. Burgundy gives a precipitate of a rosy or violet colour; and the supernatant liquor, which is not discoloured, loses its colour on the addition of ammonia, without yielding a white precipitate, although the hydrosulphurets prove the presence of bismuth.

Acetate of lead is not affected by gelatine; is precipitated by bile and wine, and yellowish white, by tincture of galls, or tea; coagulates albumen and milk. Burgundy, containing lead, loses colour, and gives a dirty yellow, instead of a white precipitate with ammonia; and although it is precipitated by the hydrosulphurets, the wine unimpregnated by the lead is affected in the same way; but hydrosulphuretted water precipitates the poisoned, and does not affect the pure wine.

As connected with the chemical history of poisons, we may here notice M. Orfila's directions for detecting them, chiefly for the sake of noticing the methodical manner in which he treats the subject. In regard to each principal poison, he describes minutely the line of conduct to be followed in four different cases; when the individual is still alive, and the remains of the poison can be procured; when he is alive, and there are no remains, but the matters vomited or passed by stool can be had; when he is alive, and there are neither remains nor egesta; and, lastly, when he is dead. M. Orfila duly appreciates the value of the processes recommended by different chemists, and

describes minutely the precautions to be taken, in order to render the examination in every possible case satisfactory. It would not be proper at present to enter into any detail upon this extensive subject; but we cannot omit noticing that M. Orfila was able, in several instances, to detect poison, both in the egesta, and when combined with the substance of the stomach.

Our readers will perceive the value of these facts, although we have been obliged to state them in the most concise manner, and to omit many altogether, that we may leave room for some account of a series of still more interesting observations on the actions of all the various corrosive poisons upon the animal economy; a subject upon which there are still many popular errors, and great obscurity. Upon each principal poison, M. Orfila arranges his observations under three heads,—its action upon the animal economy, when taken into the stomach, injected into the veins, or applied externally;-the general symptoms produced by it, illustrated by cases;-and the organic lesions to which it gives rise.

In order to ascertain the manner in which each poison produces death, M. Orfila has been obliged to perform a vast number of original experiments, which constitute a real addition to our knowledge of the subject. We conceive ourselves entitled to speak with confidence in regard to our author's merits, because we have been and are engaged in researches of a similar nature, and know their difficulty.

M. Orfila made experiments in several ways. He introduced the poison into the stomach in various doses, without in any way injuring the animal. Where the event was fatal, this mode of experimenting is without objection, and satisfactory; but when the substance is quickly rejected by vomiting, we are not entitled to pronounce it innocent, because no other bad effects follow. It is from not attending to this circumstance that many alleged antidotes have acquired unmerited reputation. In order to obviate this objection, M. Orfila, in many cases, injected the poison through a hole made in the esophagus, and then put a ligature around that canal, to prevent vomiting. In some cases, no doubt, he was in this way enabled to attain his object; but the method is liable to very great objections, as the animal is subjected to considerable injury in detaching and tying the