Note:  Do not rely on this information. It is very old.


Calcination originally signified the heating of a metal or compound in order to produce a metallic oxide. It is now employed to denote not only this process, but also any heating in suitable furnaces which effects the expulsion of some constituents of the substance heated. In the case of ores the calcination is generally for the purpose of expelling sulphur, water, or carbonic acid.