ignifies a small furnace, in which smiths and other artificers of iron, steel, or other metals, heat these metals red hot, in order to soften them and render them more malleable and manageable on the anvil.
An ordinary forge is nothing but a pair of bellows, the nozzle of which is directed upon a smooth area, on which coals are placed. The nozzle of a pair of bellows may also be directed to the bottom of any furnace, to excite the combustion of the coals placed there, by which a kind of forge is formed. In laboratories there is generally a small furnace consisting of one cylindrical piece, open at top, which has at its lower side a hole for receiving the nozzle of a double bellows. This kind of forge furnace is very convenient for fusions, as the operation is quickly performed, with a small expenditure of fuel. In its lower part, two inches above the hole for receiving the nozzle of the bellows, may be placed an iron plate of the same diameter, supported upon two horizontal bars, and pierced near its circumference with four holes diametrically opposite to each other. By this disposition, the wind of the bellows, pushed forcibly under this plate, enters at these four holes; and thus the heat of the fire is equably distributed, and the crucible in the furnace is surrounded by it. This contrivance is used in the forge-furnaces for smelting copper; with this difference only, that these furnaces are square, which, however, is a matter of little consequence.
As the wind of bellows strongly and rapidly excites the action of the fire, a forge is very convenient when a great heat is to be applied quickly; but it is not suitable when the heat is to be gradually increased.
Forge is also used for a large furnace, in which iron ore, taken out of the mine, is melted down; or it is more properly applied to another kind of furnace, in which the iron-ore, melted down and separated in a former furnace, and then cast into sows and pigs, is heated and fused over again, and beaten afterwards with large hammers, and thus rendered softer, purer, more ductile, and better fitted for use. See Furnace.