History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c37.68

c37.68

The balls containing the waste gold, as prepared above, are placed in a small hearth, the interior of which is covered with a layer of slaked lime about half an inch thick. The hearth is made by scooping out on the earth in an open place a hollow of the shape of a hemisphere about a foot in diameter. A powerful charcoal fire is produced over the balls in the hearth, which is aided by blowing air with two or three large pairs of bellows A large metallic mass ultimately collects at the bottom of the hearth, consisting mainly of lead. As the blowing is continued, lead is oxidized to litharge and gradually blown off. As the whole of the lead has passed off in this way, a mixture of gold, silver and copper remains behind.