Page:Treatise on poisons in relation to medical jurisprudence, physiology, and the practice of physic (IA treatiseonpoison00chriuoft).pdf/654

 adheres with great obstinacy. The relation of the empyreumatic oil of tobacco to these principles has not been accurately ascertained, though it probably contains one or other of them. It is well known to be an active poison, which produces convulsions, coma and death. Mr. Morries-Stirling found that its active part is removed from the oil by washing with weak acetic acid, as he also observed in the instance of similar oils obtained from various narcotic vegetables.

Process for detecting Tobacco in Organic mixtures.—In a medico-legal case which happened at Aberdeen in 1834, and of which some notice is taken at page 651, Dr. Ogston of that city successfully employed the following process for detecting tobacco in the contents of the stomach. The contents, consisting of a pulpy fluid, were acidulated with acetic acid, digested, and filtered; the liquid was treated with di-acetate of lead, filtered again, freed of lead by hydrosulphuric acid, filtered a third time, treated with caustic potash, and then allowed to settle. The supernatant liquid, which had the taste of tobacco-juice, was separated and distilled to half its volume. The distilled liquor had a strong tobacco odour and taste, and some acridity, and gave a precipitate with infusion of galls. The residuum in the retort presented oily particles on its surface, and when heated in an open basin filled the apartment with a vapour which had a strong odour of tobacco smoke, and caused in several persons present a sense of acridity of the throat, watering of the eyes, and tendency to sneeze. Various additional experiments confirmatory of these results were also performed; and a simultaneous examination of tobacco-powder gave precisely the same indications. I am indebted to Dr. Ogston for these particulars and a detailed narrative of his investigation; which appears to supply a convenient and conclusive process for the detection of tobacco.—Perhaps the ordinary process for obtaining nicotina may also be employed with advantage. This consists in distilling the suspected substance with caustic potash, neutralizing the distilled liquor with sulphuric acid, concentrating the product to a thin syrup, exhausting this with etherized alcohol, evaporating off the solvent, and distilling the extract with strong solution of potash. Nicotina passes over, and may be recognized by its sensible and chemical qualities.

The effects of tobacco are somewhat different from those of belladonna and thorn-apple; but it is here arranged with them, as it belongs to the same natural family. Orfila remarked that 5-1/2 drachms of common rappee, introduced into the stomach of a dog and secured by a ligature, caused nausea, giddiness, stupor, twitches in the muscles of the neck, and death in nine hours; and that two drachms and a quarter applied to a wound proved fatal in a single hour. Mr. Blake thinks tobacco has no direct action on the heart, even when admitted directly into the blood by the jugular vein;—that it acts primarily on the capillary circulation of the lungs, by obstructing which it prevents the blood from reaching the left cavities of the heart, and thus acts on that organ indirectly. For he observed, that laboured respiration always preceded any sign of depressed action of the heart, that forci-*