A
very ancient traditionary process was evidently the method of refining
silver used in the Delhi mint, as follows : " They dig a hole, and
having sprinkled in it a small quantity of the ashes of field
cow-dung, they fill it with the ashes of Babool-wood, then they moisten
it, and work it up into the shape of a dish or coppel ; into this they
put the adulterated silver together with an equal quantity of lead
after the following manner : 1st. They put with the silver the fourth
part of the lead, and surrounding the coppel with coals blow the fire
until the metals are melted. This operation they repeat as often as is
necessary, but in most instances four times are required. The proofs of
the metal being pure are the brightness thereof, and its beginning to
harden at the sides. When it is hardened in the middle they sprinkle it
with water, when if a flame issues from it, it is arrived at the
required degree of fineness, and if they melt this mass again there
will be lost half a ruttee in every tolah (one part in 192). The coppel becomes a kind of litharge which in the Hindustani language they call kehrel."
The ancients, who classed minerals for the most part by the eye, considered native Quicksilver, " argentum vivum," as
a rare variety of this metal, occurring in the same mines, like a
running issue, always liquid, proceeding from the metallic veins, "
vomica liquoris aeterni." They imagined it to be something quite
different from the " Hydrargyrum" extracted from the Minium (Sulphuret
of Mercury) by sublimation. This Minium,* the Vermilion used in
painting, Theophrastus relates, was, eighty years before his time,
discovered by Callias, an Athenian, who, from the brilliant red of the
ore, imagined it contained gold, and making experiments upon it, failed
in that expectation,
* Miniaria (fedina), the quicksilver-mine, is the source of the Italian " miniera," and of our " mine."
