The Positive Sciences of the Ancient Hindus c4.s2.21

c4.s2.21

*Preparation of Chemical Compounds.*—The knowledge of chemical compounds and of their preparation continued to make progress in the Charaka and Susruta schools. The great metallurgist, Patañjali, in his treatise on Metallurgy (लोहशास्त्र), gave elaborate directions for many metallurgic and chemical processes, especially the preparation of the metallic salts, alloys, and amalgams, and the extraction, purification, and assaying of metals. Probably it was Patañjali who discovered the use of the mixtures called Vidas, which contained aqua regia or other mineral acids *in potentia*. Unfortunately Patañjali's *magnum opus* appears to have been lost, but extracts from it are frequently found in mediæval works on Medicine and Rasáyana which leave no doubt as to its remarkable scientific value. The metallurgist Nágárjuna advanced the knowledge of chemical compounds by his preparations of mercury. The Harshacharita, in the seventh century, relates a fable concerning this Nágárjuna, and speaks of him as a friend and contemporary of Sátaváhana. The relative priority of Patañjali and Nágárjuna is a vexed question in the history of metallurgy. That Nágárjuna's Lohasástra was earlier than the final redaction of Patañjali will appear from the following circumstances:—(1) Chakradatta in his summary of Nágárjuna mentions that the chemical process of testing pure iron must be repeated twice before it can be regarded as decisive, whereas Śivadása Sen's extract from Patañjali shows that the latter directed the process to be repeated seven times; (2) Patañjali in the Abhraka-vidhi (mica operation) adds mercury, which in this particular operation is wanting in Nágárjuna's recipe (*cf.* Chakradatta, and Patañjali as reported in the Yogaratnákara-samuchchaya); and (3) Nágárjuna is quoted in the earlier compilations, Patañjali in the later.