naphtha năp´thə, năf´– [key], term usually restricted to a class of colorless, volatile, flammable liquid hydrocarbon mixtures. Obtained as one of the more volatile fractions in the fractional distillation of petroleum (when it is known as petroleum naphtha), in the fractional distillation of coal tar (coal-tar naphtha), and in a similar distillation of wood (wood naphtha), it is used widely as a solvent for various organic substances, such as fats and rubber, and in the making of varnish. Because of its dissolving property it is important as a cleaning fluid; it is also incorporated in certain laundry soaps. Coal-tar (aromatic) naphthas have greater solvent power than petroleum (aliphatic) naphthas. Originally the term naphtha designated a colorless flammable liquid obtained from the ground in Persia. Later it came to be applied to a number of other natural liquid substances having similar properties. Technically, gasoline and kerosene are considered naphthas.

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