Fuel
Fuel is a term of general application to all combustibles employed for producing heat. The two elementary bodies which produce the heating power of fuels, both natural and artificial, are hydrogen and carbon; and as there is little or none of the former element contained in anthracite, peat charcoal, wood charcoal, or coke, we may therefore regard these as carbonaceous fuels. But wood, peat, and most varieties of coal contain hydrogen as well as carbon, and in their combustion these two substances combine to produce volatile and combustible hydrocarbons, which are volatilized previous to being consumed; while a purely carbonaceous fuel evolves no volatile matter until combustion has been effected. See COMBUSTION; COAL; COKE; PETROLEUM; PRESSED FUEL; LIQUID FUEL.