History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c13.s2.t8.6

v1.c13.s2.t8.6

It is found in nature mostly as Arsenide (As₂S) and as As₂O₃ which have a very low boiling point. Although the hardening effect of this element on copper was known from antiquity this element in the metallic form was known only in 1694. Earlier Arsenic sulphate found in the copper sulphate ore was probably co-reduced to produce Cu-As alloy which had higher hardness (220 to 230 BHN) as compared to the cold worked copper. This property was well recognised by the copper age people and used to produce hard and sharp edge on copper weapons.