thar, or other metallic oxides, and gum-water, which is the material for drawing on it, and by burning the same under a muffle.
Carnelian
is divided into Oriental and occidental; the first is found in the old
rocks, and is generally very hard, rich in color, clear and
transparent, and takes a high polish, is brought from Surat, in the
Indies, and valued at ten francs the kilogramme ; the occidental
carnelian is softer, of a yellower red and less brilliant.
Stygmite
is a beautiful variety with variegated colors, of reddish-yellow or
yellowish-red, with many white lines passing through the stones.
The
ancients, particularly the Romans, were very partial to engraving on
carnelian, and some very remarkable stones are still in existence in
the imperial library at Paris. The seal of Michael Angelo, which is
valued at 50,000 francs, is said to have been engraved by Maria de
Descias after the original of Praxiteles; the bust of Ulysses, Hercules
killing Diomede, Jupiter, Mars, and Mercury.
The
great scarabee in carnelian, in the Prussian cabinet, which represents
the five heroes of Thebes, is a master-piece of Etruscan art.
The crown jewels of France contain some very costly carnelian engravings of very large size.
The
faults of the carnelian are fissures, unequal color, and flaws from
other stones. Carnelian is, on account of its being less brittle, more
useful for engraving and cutting cameos ; the white layers are
generally used for the figures of cameos and the red for the base.
Sometimes such carnelians as are cut with bas-relief objects, are
filled out with colored strass; and we receive from India, very
frequently, cameos with the most singular drawings, and which are made
by the inhabitants in the following manner: the whole carnelian is
covered with carbonate of soda, and then
