X.—Nitro-Benzene.
§ 239.—Nitro-benzene is the product resulting from the action of strong nitric acid on benzene. Its chemical formula is C6H5NO2. When pure, it is of a pale yellow colour, of a density of 1·186, and boils at from 205° to 210°. It may be obtained in prismatic crystals by exposure to a temperature of 3°. Its smell is exactly the same as that from the oil or essence of bitter almonds; and it is from this circumstance, under the name of “essence of mirbane,” much used in the preparation of perfumes and flavouring agents.
In commerce there are three kinds of nitro-benzene—the purest, with the characters given above; a heavier nitro-benzene, boiling at 210° to 220°; and a very heavy variety, boiling at 222° to 235° The last is specially used for the preparation of aniline, or aniline blue. Nitro-benzene has been used as an adulterant of bitter almond oil, but the detection is easy (see “Foods,” p. 551). Nitro-benzene was first discovered by Mitscherlich in 1834, and its poisonous properties were first pointed out by Casper[219] in 1859. Its technical use in perfumes, &c., dates from about 1848, and in the twenty-eight years intervening between that date and 1876, Jübell[220] has collected 42 cases of poisoning by this agent, 13 of which were fatal. One of these cases was suicidal, the rest accidental.
[219] Vierteljahrsschrift für ger. Med., 1859, Bd. xvi. p. 1.
[220] Die Vergiftungen mit Blausäure u. Nitro-benzol in forensischer Beziehung, Erlangen, 1876.
§ 240. Effects of Poisoning by Nitro-benzene.—Nitro-benzene is a very powerful poison, whether taken in the form of vapour or as a liquid. The action of the vapour on animals has been studied by Eulenberg[221] and others. One experiment will serve as an illustration. Fifteen grms. of nitro-benzene were evaporated on warm sand under a glass shade, into which a cat was introduced. There was immediately observed in the animal much salivation, and quickened and laboured breathing. After thirty minutes’ exposure, on removing the shade to repeat the dose of 15 grms., the cat for the moment escaped. On being put back there was again noticed the salivation and running at the eyes, with giddiness, and repeated rising and falling. The animal at last, about one hour and forty minutes after the first dose, succumbed with dyspnœa, and died with progressive paralysis of the respiration. The membranes of the brain were found gorged with blood, the lungs liver-coloured, the mucous membrane of the trachea—to the finest sub-divisions of the bronchia—reddened, inflamed, and clothed with a fine frothy mucus. The left side of the heart was filled with thick black blood. The bladder contained 8 grms. of clear urine, in which aniline was discovered. There was a notable smell of bitter almonds.
[221] Gewerbe Hygiene, S. 607, Berlin, 1876.