History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c37.s1.19

c37.s1.19

The term *dravaka* (solvent) seems to have been expressly coined to do duty for the mineral acids. We have seen all along that in the older works *dravaka* was used invariably in the sense of solvent or flux, but never in the sense of a mineral acid, the knowledge of which seems to have spread both in the east and the west almost simultaneously. The regular application of the mineral acids to technical operations dates from the time of Emperor Akbar or perhaps a little earlier Thus in the *Ayeen Akbari* under the "Method of Refining Silver" mention is made of the use of *rası* (aqua fortis). It is not easy to make out how much of the processes of the assay of gold and silver, as described in the *Ayeen*, is of earlier origin