Origin. - A hydrocarbon (C10H8) obtained from coal-tar.

Description and Properties. - Colorless, shining, transparent laminae, having a strong, characteristic odor resembling that of coal-tar, and a burning, aromatic taste; slowly volatilized on exposure to air. Insoluble in water, but when boiled in it imparting a faint odor and taste. Soluble in 15 parts of alcohol, and very soluble in boiling alcohol; also very soluble in ether, chloroform, carbon disulphide, and in fixed or volatile oils. Naphthalene volatilizes slowly at ordinary temperatures, but rapidly when heated. Its vapor is inflammable, burning with a luminous and smoky flame. It should be kept in well-stoppered bottles.

Dose. - 2-10 grains (0.12-0.6 Gm.) [2 grains (0.125 Gm.), U. S. P.].