Minerals and Metals in Ancient India v2.c40.s4.9

v2.c40.s4.9

Certain unit operations, though not practised in the area of minerals and metals, were very useful in terms of food processing. We have indicated that winnowing or nispāva using a winnow or śūrpa was widely practised in the ancient India, starting from the Harappan age, for separating grain from husk. Niṣkoṣaṇa meant extraction in the sense of husking shelling of grains, disembowelling, de-seeding of fruits, etc. (Pāṇ., 5.4.62). Such a technique was used for removing the cortex from agate mineral grains also. Su and āsu meant to press out the juice from materials like soma plant-stem and tendril, and the oil from the vegetable oil-seeds (Pāṇ., 3.1.126; 3.2.103; 7.2.72, etc.). After squeezing the juice out, it was necessary to strain or filter the soma-juice, etc. free from suspended solids. Wire-mesh, fibre-mesh or cloth was used as a filtering medium. Such a step of purification was known as prapavana (Pāṇ., 8.4.34), this word being one more in the series derived from the base pu meaning purification.