Naphthalene — Chambers's Encyclopaedia

Naphthalene, $C_{10}H_8$ , is a solid substance obtained from Coal-tar (q.v.). It forms thin, transparent, brilliant plates with a pearly lustre and unctuous to the touch. It melts at $176^\circ$ ( $80^\circ$ C.) and boils at $422^\circ$ ( $217^\circ$ C.), but it readily sublimes at a much lower temperature. Although not very inflammable, it is used (as in the Albo-carbon light) to increase the illuminating power of coal-gas, the naphthalene being placed in a metal receiver heated by the gas-flame, and the illuminating gas passed slowly through. A smoky but brilliant light is thus obtained which under some circumstances may be useful. Naphthalene is of most importance from a scientific standpoint. Its molecule of $C_{10}H_8$ may be regarded as made up of two aromatic nuclei, having two atoms of carbon in common; but for further information on this point, see AROMATIC SERIES. Naphthalene forms an extensive series of derivatives in which one or more atoms of hydrogen are replaced by $NO_2$ —chlorine, bromine, &c.