The great convenience of natural and producer gas as fuel in reverberatory, steel-making, and metal-heating furnaces has caused extensive use of gas fuel in all metal industries.

For furnace use a more concentrated and more intense heat can be obtained from gas than from coal, as a less volume of air enters the furnace with the gas, thus necessitating the heating of less inert nitrogen which enters with the air. The heat from gas can be regulated and directed better than that from coal, and gas leaves no ash nor clinker.