History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c12.s1.6

c12.s1.6

(*c*) The percentage of tin in the bronze articles found at the Indus Valley sites lies between 4.51 to 13.21. Those with 11-13 per cent of tin are more common, although lower grades also occur to some extent. The presence of the high grade alloys well-suited for sharp-edged tools, with a fairly regular proportion of tin, leaves hardly any doubt that the addition of the white metal was intentional and not the result of mere accident. Tin was possibly imported from outside, likely from Persia. It is obvious that this stage in metallurgy had been reached after prolonged experimentation and experience with copper and its alloys with arsenic and tin. An appreciable amount of antimony and arsenic has been found in many bronze articles, which thereby gain an increased hardness.