A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c20.3

v1.c20.3

mercury (i. e. sulphide of mercury) and sublime the mixture in a closed crucible. On repeating the process 8 times, the gold is killed." (Cf. also the processes described in pp. 105-106). In the preparation of "makaradhvaja" (p. 132, note) the gold, which is left behind, would be regarded in the same light. As the Hindu Iatro-chemists were very particular about the killing of the metals being ensured, they had often to hit upon proper tests for securing this purpose. Thus "Rasaratnākara" says:—"In order to examine whether the mercury has been completely reduced to ashes, it has to be heated over a gentle fire for 3 hours. If the weight remains constant, know then that it has been completely killed." In other words it means that if there be any free mercury present, it would volatilise off and thus there would be a loss in weight. In page 118 will also be found some tests for killed iron. The language of a portion of couplets 25-28 is somewhat obscure and the meaning seems to be the very reverse of what the context would suggest; "killed iron is that which, on being mixed with treacle......honey and heated, does not revert to the natural state." By "natural state" the author probably conveys the state in which it originally was.