Before the close of 16th century,zinc was
isolated by a process known neither to the Arab Civilisation nor the Europeans
who learnt the art in the early 19th century. It has now been
suggested by archaeological excavations at Zawar in Rajasthan that Indians knew
how to isolate zinc by about the 1st century Christ.
The isolation of zinc was accompanied by another
achievement, namely the manufacture of brass, an alloy of copper and zinc.
India seems to have discovered the freezing mixture before Europe. Saltpetre
(potassium nitrate) was used for cooling water before 1580. This discovery has
been attributed to Emperor Akbar.