Minerals and Metals in Ancient India v1.c26.s4.3

v1.c26.s4.3

It is conceivable that the retorts were being used in the said context for roasting zinc ore to obtain the light, white, smoky zinc oxide, which the ancient Greeks called pompholyx, philosopher’s wool. In the modern zinc plant at Udaipur, roasting of zinc sulphide concentrate produces not only zinc oxide (and sulphur dioxide gas) but also some zinc sulphate which was noticed in the fourth-third century BC retort in Rampura-Agucha*. The said retorts, already found sealed at one end, must have been closed or sealed at the other and also to prevent the escape of smoky zinc oxide into the atmosphere. The retorts were possibly modified to serve as reduction distillation chambers (to produce metallic zinc), the final version of which, noticed in the thirteenth century AD context, would be described later. Very significantly, Tiwari *et al.* (1984: 85) noted that the slag sample (no. 4 in Table 17. 4) containing only 0.01 per cent zinc but as high as 9.30 per cent lead, was “attached to baked earthen materials which could be the part of the earthen appliance used for smelting”. We suggest the possibility that the earthen appliance was a zinc distillation retort.