History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c15.122

c15.122

For the roasting of iron thin leaves of the metal are to be smeared with the levigated powder of the salts including common salt, saltpetre and sulphate of magnesia, and heated in the fire of cow-dung cakes. The process is to be repeated sixteen times. The method is equally applicable to the other metals. The metals are no doubt converted hereby into their respective oxides, or oxychlorides as the case may be. Susruta thus describes a practical method, though crude and imperfect, for the preparation of metallic salts. The process has been given the general name, *ayaskriti*, which means action affecting the metals. The much reputed ‘potable gold’ in the shape of the the chloride of the metal was probably obtained in this manner. Two types of iron pyrites with the lustre of gold and silver have been described in the Susruta, denoting obviously those containing copper and those free from copper respectively.