A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v2.c33.s2.7

v2.c33.s2.7

That copper, lead, tin and other base metals (हीनधातवः) when repeatedly calcined are completely reduced to their calces was well known as will be seen throughout the body of the texts. The passage from Rasendra-chūḍāmani (p. 14) deserves some notice. Lead of the weight of 30 palas is to be calcined till its weight is reduced to a karsha (=1/4 pala). Even if it be calcined now one thousand times, it will not undergo further reduction in weight. Our author evidently had his experience of lead derived from argentiferous galena, which would leave a residue in the shape of a "button" of silver after the lead had been cupelled off.*