Minerals and Metals in Ancient India v2.c45.s7.8

v2.c45.s7.8

Several techniques of smelting were discussed. According to the first method, the dried charge was to be heated in the crucible, closed and stacked one over another (mūṣām mūṣopari nyasya) and the reduction was supposed to be complete as soon as the blue flame (due to carbon monoxide) turned white (jvāla bhaved nilā sitā yadi), when the crucible was to be gripped by a pair of tongs and tilted to pour the molten metal (2.157-161). The second method involved mixing the charge thoroughly with binders and putting this in the crucible as pellets (gutikākrti) (2.163-164). The third method involved disillation of the produced zinc metal in the inverted crucible (adhomukham mūṣā) and collection of the condensed vapour in a vessel filled with water kept in a hermetically sealed container below the crucible (patitam sthālikā nīre satvam) (2.165-166). This last method was commercially followed in India.