Liquefied petroleum gas; LP-gas; "bottled gas"; butane, propane and other fight ends (q.v.) separated from natural gasoline or crude oil by fractionation or other refining processes. At atmospheric pressure, liquefied petroleum gases revert to the gaseous state. Liquid butane and propane or a mixture of the two are used extensively in areas where there is no natural gas service. When the valve on the "bottle" or small tank of butane, for example, is opened, releasing the pressure on the liquid, a small quantity of liquid "boils" or turns to a gas and can then be used just as natural gas for cooking or heating.
