Prehistoric India to 1000 B.C. c12.168

c12.168

The techniques employed in Harappā metallurgy included casting and forging - the former process, of course, is dependent on melting the metal before it is poured into a mould. But casting was never developed in prehistoric India to the pitch it was in early Sumer, and this simpler technique resulted in the preservation of certain very primitive forms of tool which soon became demoded in other areas of Western Asia. Copper is a difficult metal to cast in a closed mould, owing to the bubbles of free oxygen which tend to make the casting spongy, but the addition of a very small percentage of tin (under 1 per cent.) or of arsenic acts as a de-oxidizing agent. This permits good castings to be made even by the complicated *cire perdue* method, in which a model is made in wax, coated in clay, and then heated until the wax is melted and absorbed in the baked mould; the molten metal can then be poured in to take the exact shape of the original wax model. Such figures as the Dancing-Girl from Mohenjo-daro must have been cast by this process, with subsequent work in chasing and finishing the surface; and the little model canopied carts were also presumably made in this manner. But the curious fact is that closed-mould casting, either by *cire perdue* or by less ambitious processes involving moulds in more than one piece, was never used in the Harappā civilization to produce tools which gripped their hafts by means of a socket, although this technique was discovered in Sumer in very early times and from this centre its adoption was rapid in most regions round about.