Copper in Ancient India c11.s2.2

c11.s2.2

That blue vitriol yields copper on heating with organic substances and borax in closed crucibles was discovered in India in the 12th century, as we find the following formula in *Rasārnava*—"Take blue vitriol and one-fourth its weight of borax and soak the mixture in the oil expressed from the seeds of pongamia glabra for one day only and then place it in a covered crucible and heat in the charcoal fire—by this process an essence is obtained from it of the beautiful appearance of coccinella insect."[¹] This formula is repeated in *Rasaratna-samuchchaya* which also prescribes that when blue vitriol is