Xylene, Or Xylol, a hydrocarbon homologous with benzene and toluene, first obtained in a pure state from coal naphtha by Hugo Miller in 1863. Mixed with toluene and several other hydrocarbons, it had been obtained several years previously. It is prepared by subjecting coal naphtha to fractional distillation, and subjecting that portion which boils at about 306° F. to the action of oil of vitriol containing some of the fuming acid, which converts the xylene into xylene-sulphuric acid; and this, being decomposed by dry distillation, yields pure xylene by washing, drying, and redistillation. Its formula is C8H10. It is a colorless liquid, having a peculiar, faint odor; sp. gr. 0-.6 at 66°; boiling point, 282°. Passed in a state of vapor through a red-hot tube, xylene is resolved into a mixture of several hydrocarbons, such as benzene, toluene, naphthaline, and anthracene. Xylene has several derivatives called xylenes, as the bromo-xylenes, chloro-xylenes, ethyle-xylene, methyle-xylene, the nitro-xylenes, and others.

When nitroxylene is subjected to the action of ferrous acetate or stannous chloride, a base homologous with aniline is produced, which ha3 received the name of xylidine, C8H11N.