The Indus Civilization c8.5

c8.5

The use of tin to alloy copper has the effect of hardening the latter and also facilitates casting, but too much tin makes a brittle product. As a rule 9 to 12 per cent. of tin suffices for ordinary purposes, but in some of the bronze from Mohenjo-daro over 26 per cent. has been found. It would seem that the metal workers of the city, like the early Sumerians, either used no fixed proportion of tin to copper or obtained their bronze ready mixed from sources over which they had no control.