Minerals and Metals in Ancient India v2.c44.s1.12

v2.c44.s1.12

Elaborate descriptions about the preparation and properties of alkali carbonates (prepared by lixiviation of burnt plant ash) and caustic alkali (lixiviation of burnt limestone, conch-shell and bivalve shells) were provided in *Suśruta Saṃhitā*. Mild (*mṛdu*), medium strength (*madhyama*) and strong (*tīkṣṇa*) solutions of alkali (*kṣāra*) were prepared by lixiviation and successive operations of evaporation and concentration. There was widespread use of caustic alkali solutions for cauterisation in surgery. The application of the pungent acid of *kañjika* (fermented rice water, i.e., crude vinegar) was known to relieve the burning sensation and taste of the ‘fire-like hot alkaline caustic’, ‘just as fire is extinguished by water’. Distinction was made between *yavakṣāra* (factitious carbonate of potash) and *sarjikākṣāra* (carbonate and bicarbonate of soda from river bed alluvium).