62 PRECIOUS STONES.
very
hard Stones, such as Blood-Stone, and Granates (even unpowder'd) : nay,
and though Rubys seem to be the hardest Bodies yet known, save Diamonds
(for I have learn'd from those that cut Precious Stones that they can
grind other Gems with the powder of Rubies, but not these with any
powder save their own, and that of Diamonds,) yet have even these
afforded me in the cold a not ignoble Tincture."
"
And, since, as we have now shown, one Liquor, prepared by Nature only,
could dissolve that great variety of bodies mentioned above, why should
it not be thought that some other Menstruum wherein Nature is skilfully
assisted, and to the utmost heightened, by art, should not be able to
dissolve concretes such as the Precious Stones, of different degrees of
hardness ? Why may not Nature, and Art, afford a Menstruum whose
variety of parts and figures, and (perhaps also motion) may give it
ingress into bodies of the most varying textures ? Just as chemically,
though Aqua Regia will dissolve Gold, but not Silver, and Aqua Fortis
Silver, but not Gold ; yet Quick-silver will dissolve both, (and
Copper, Tin, and Lead, to boot)."
"
As to the efficacy of the aforesaid Menstruum (concocted' from Bread,
as described,) I have found," says Robert Boyle, " that from some
Minerals it will draw a much higher Tincture than from others ; and
from some scarce any at all; but that it will, if kept by itself, for
many Moneths, continue clear, and limpid."
Helmont
relates, " that the noted Irish physician, Dr. Butler, by slightly
plunging a little stone which he possessed, into Almond Milk, or Oyl,
imbued those liquors with such a sanative efficacy that a spoon-full of
the former cured (and that without acquainting him
