Nicotia, Or Nicotine (C10H14N2), a volatile alkaloid, the active principle of tobacco, discovered by Vauquelin in 1809, and obtained by Posselt and Reimann in 1828 in a state of comparative purity. It may be prepared by the distillation of the infusion of the plant. It is a clear oily fluid, of specific gravity 1.048, soluble in water, alcohol, ether, the fixed oils, and oil of turpentine. It possesses an exceedingly acrid burning taste, even when largely diluted, and an odor like that of tobacco. Its vapor is very powerful and irritant to the nostrils; that arising from a single drop is sufficient to render the whole atmosphere of a room insupportable. Nicotia partly decomposes at 482°, and becomes brown and thick on exposure to the air. It has a strong alkaline reac-tion, and forms crystallizable salts with the acids. It is one of the most virulent poisons known, a drop of anhydrous and pure nicotia being sufficient to kill a dog in from half a minute to two minutes. Tannin combines with it to form a compound of little solubility, and it may therefore serve as a temporary antidote to the poison if there be time for its application. Nicotia has been used in criminal poisoning, and in the celebrated case of Count Bocarme it was detected in the body of the victim.

It protects the animal tissues from decomposition, and Orfila found it several months after death in bodies of animals destroyed by it. The proportion of the alkaloid obtained by this chemist from Havana tobacco was 2 per cent., from that of Maryland 2.3, and from that of Virginia 6.9. The empyreumatic oil of tobacco, which imparts the well known odor to old tobacco pipes, contains a large proportion of nicotia, and is a virulent poison. - Nicotianine is probably the odorous principle of tobacco. It is a fatty substance having the smell of tobacco smoke, and an aromatic, somewhat bitter taste. It produces sneezing when applied to the nostrils, and a grain of it swallowed occasions nausea, (See Tobacco).