Nicotine

Nicotine, $C\_\{10\}H\_\{14\}N\_2$, is a volatile liquid alkaloid, and constitutes the active principle of the tobacco-plant, in all parts of which it occurs in combination with malic and citric acids. It is likewise contained in minute amount in the smoke of the burning leaves. When pure and freshly prepared it is a colourless, intensely poisonous liquid, which evolves a very irritating odour of tobacco, but on exposure to the air it rapidly oxidises and becomes brown in colour. It is moderately soluble in water, and dissolves readily in alcohol and ether. The quantity of nicotine in tobacco varies from 2 to 8 per cent.; the coarser kinds contain the larger quantity, while the best Havana cigars seldom have more than 2 per cent., and often less. Locally, nicotine is very irritating. Taken internally, it is one of the most powerful poisons known; $\backslash frac\{1\}\{100\}$ grain taken by the mouth has caused in man distinct symptoms of poisoning, there being first seen a short stage of excitement, followed by headache, vertigo, great weakness, and general depression. Larger doses ($\backslash frac\{1\}\{10\}$ grain) caused in addition trembling, vomiting, collapse, and great depression of the heart and respiration. A single drop is sufficient to kill a rabbit or cat in a few minutes. It has been used rarely for homicidal and suicidal purposes, but the minimum lethal dose in man is not accurately known.