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The whole is covered with a bell-jar, or a beakerglass. The alcohol is converted into aldehyde and acetic acid; the latter is easily recognized by its odor and its acid reaction.
[If the analyst has a comparatively large quantity of alcohol at his disposal, the conversion into acetic acid may be effected in the following manner: A glass-rod is loosely fitted into the neck of a small glass funnel ; into the latter some platinum-black is placed, and moistened with a few drops of distilled water. The alcoholic liquid is then made to flow very slowly on the platinum-black, which is effected by means of a cotton string, serving as a syphon. The acid liquid which drops down from the funnel, is carefully neutralized with a very dilute solution of caustic potassa, and evaporated to dryness over a water-bath. The acetate thus obtained, may then be tested with the usual reagents for acetic acid.
The platinum-black for these experiments is most conveniently prepared, by placing a zinc-rod in a dilute solution of bichloride of platinum, and washing the precipitate with hydrocholoric acid, then with nitric acid, and finally with a solution of caustic potassa.]
If a sufficient quantity of the distillate is obtained, its specific gravity may be ascertained, by weighing it in a small bottle, and thus the amount of alcohol can be determined.
$ 100. Buchheim recommends the following method for the detection of very minute quantities of alcohol. The substances under examination, previously neutralized with caustic or carbonate of soda, if necessary, are placed into a tubulated retort, the
neck of which has been cut off far enough, to allow the introduction of a capsule of platinum, silver, glass, or porcelain. The capsule into which some platinumblack is laid, is placed into the neck of the retort at the spot where it joins the body. At each end of the capsule, a piece of moistened litmus-paper is fastened, so as to be partially in contact with the platinum-black. The distillation is performed over a water-bath. As soon as the first drops of liquid appear in the neck of the retort, that part of the litmus-paper which is in contact with the platinum-black becomes reddened, even if but traces of alcohol are present. The rest of the paper remains blue, proving to evidence, that the acid does not come from the contents of the retort, but originates within the platinum-black. [If the operation has proceeded for some time, so that some drops of liquid have already flown out from the beak of the retort, and the litmus-paper remained unchanged, it may safely be concluded, that there is no alcohol present. But if the paper begin quickly to redden, the capsule may be withdrawn, and the beak connected with a receiver. The distillate is rectified as above de- . scribed.]
§ 101. Morin (De l'alcool considéré sous le rapport toxicologique, par M. Morin), has communicated to ine a case, where a strong odor of ether was noticed at the dissection of a man, who had drowned himself in a state of drunkenness. The contents of the stomach, previously neutralized with carbonate of soda, were distilled; a slightly opalescent liquid of distinct ethereal odor was obtained. The distillate was mixed
with pure carbonate of potassa, as long as fresh portions of the salt dissolved in the liquid, and left to rest. After some time, a thin layer of liquid separated, which possessed the odor of ether, and was combustible.
Morin is inclined to think that under certain circumstances, alcohol in the stomach may be converted into ether. · $ 102. The separation of chloroform from the matters with which it is mixed, and its detection in the body, is effected in the same manner as that of alcohol.
If a liquid containing chloroform is introduced into a flask, into the neck of which a glass-tube, bent at a right angle, is inserted by means of a perforated cork, if the liquid is then heated, while a portion of the horizontal part of the tube is kept redhot, the vaporized chloroform is decomposed into carbon, hydrochloric acid, and chlorine. If a slip of paper, impregnated with starch-paste containing iodide of potassium, is held into the open tube, it becomes blue. (Ragsky, Orfila's Toxicology). This method, by which the smallest quantities of chloroform may be detected, has proved, by experiments executed in my laboratory, to be very correct and delicate.
In regard to the execution of the experiment, the remark might not be superfluous, that the tube ought to be heated to redness, and the paper introduced before heat is applied to the liquid, because the blue compound of iodine with starch is destroyed by heat. If, therefore, the liquid is heated to ebullition before the paper is introduced, the heat of the vapor will prevent the formation of the characteristic compound. The color may, of course, disappear after a while, by either heat, or an excess of chlorine.
ON THE DETECTION OF POISONOUS ALKALOIDS.
103. CASES of poisoning with alkaloids are of coaratively rare occurrence [in countries where thews of a well-regulated medical police restrict, the sale of these dangerous drugs. In England, and in this country, where such restrictions are wanting, very many cases of fatal poisoning with these substances are known, at least a sufficient number to make the knowledge of exact and reliable methods for their detection, appear very desirable.]
For some alkaloids, when in the pure state, we have very characteristic tests, not less so than for the inorganic poisons; thus, for instance, for strychnine and morphine; but the separation, in the pure state, of very minute quantities of these poisons from the contents, food, etc., requires a very high degree of practical knowledge, and a most practiced hand; and yet, their separation in the purest condition possible, is necessary; because a very minute intermixture of any foreign substance, frequently renders the tests used for their detection fallacious.
For other alkaloids, again, we are utterly destitute