1. General
A furnace is an industrial oven, an enclosed combustion chamber whose heat is either used to heat the space external to it or to to process whatever is placed in the space contained within it.
In the Middle Ages, crafts and trades, industrial trades and crafts, and the metal industry used furnaces to collect process heat, especially in the smelting process, in separating, sifting, and burning, as well as in shaping and casting metals and in chemical technologies (Chemical sciences; see Laborato…