Natural Gas
Gas-springs or gas-wells through which issue combustible gases from the earth are to be found in various parts of the world. It was by this means that the holy fires of Baku, on the Caspian, and the sacred fires of the Greeks were supplied with fuel. It is supposed to be the same as the fire-damp of coal-mines, which is liberated by the pick of the miner. In all cases these combustible gases consist to a large extent of marsh-gas, also called light carburetted hydrogen. (See MARSH-GAS.) In many cities throughout the States, notably Pittsburg, the gas is used altogether as a steam-producer; for heating metals,--iron, steel, brass, etc.,--in the diverse branches of their utilization, except for smelting ore, in which coke continues still to be employed. Natural gas has an intense heating-power, is free from substances deleterious to metals, is cheap and easily handled, and leaves no ashes. One thousand cubic feet of gas is equivalent in heating-power to 56 pounds of coal, which represents a saving of 20 per cent at first cost, besides the labor of handling and transportation. See FUEL.