214 A POPULAR TREATISE ON GEMS.
these
gems in general, and the high price at which the rubies were then sold
in market, formed a very singular contrast while viewing so large a
stock in one establishment. I only recollect from memory what I saw in
1851, at Messrs. Blogg & Martin's; the sight of so many valuable gems had, however, made a lasting impression-on me.
CORUNDUM.
The
above name was applied to a different species from that of sapphire,
but these terms are now generally acknowledged to be synonymous; not
so, however, the emery, which does not belong to this species.
Both
occur in rhomboids; often, too, in crystals of secondary form. They
scratch all other gems except the diamond; their streak and powder are
white, and the specific gravity is 3-9-4 ; they acquire
electricity by rubbing, which is retained for several hours; they are
not fusible before the blowpipe; with difficulty, by means of borax,
they form a clear, limpid glass; acids have no effect on them; their
phemical constituents are alumine, silica, and oxide of iron.
SAPPHIRE.
This
name is derived probably from the Hebrew, as it is often mentioned in
the Bible. It is not certain whether' the ancients were acquainted with
the blue variety only of this gem, and were ignorant of other blue
stones, such as lazulite, fluor spar, &c. It was not used by them
as a gem, probably on account of the difficulty of working it; but as a
medicine, many peculiar virtues were ascribed to it. This species has
hitherto been usually divided according to its different colors. The
name of ruby has reference to a red color, and was applied by the
ancients to the car-
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