Gasoline
. Gasoline, mixture of the lighter liquid hydrocarbons used chiefly as a fuel for internal-combustion engines. It is produced by the fractional distillation of petroleum ; by condensation or adsorption from natural gas; by thermal or catalytic decomposition of petroleum or its fractions; by the hydrogenation of producer gas or coal; or by the polymerization of hydrocarbons of lower molecular weight. Gasoline produced by the direct distillation of crude petroleum is known as straight-run gasoline. It is usually distilled continuously in a bubble tower, which separates the gasoline from the other fractions of the oil having higher boiling points, such as kerosene, fuel oil, lubricating oil, and grease. The range of temperatures in which gasoline boils and is distilled off is roughly between 38° and 205° C (100° and 400° F). The yield of gasoline from this process varies from about 1 percent to about 50 percent, depending on the petroleum. Straight-run gasoline now makes up only a small...