174 A POPULAR TREATISE ON GEMS.
ceding
mixture for the topaz by the addition of eight parts more of strass,
and left for thirty hours in fusion; when taken out and fused before
the blowpipe, it yields a most beautiful Oriental ruby. Five ounces
strass and one drachm oxide of manganese may be employed for the same
purpose, but will not make so fine a ruby. Or by calcining ammoniacal
alum with chromate of potash and lampblack, which forms the composition
of
97 parts alumine,
1 " oxide of chrome,
2 " silica and lime.
C. Artificial Emerald. To one pound of strass add one drachm of verdigris and fifteen grains crocus martis.
D. Artificial Sapphire. Add to eight ounces of strass fifty-two grains pure oxide of cobalt.
E. Artificial Amethyst. To
eight ounces of strass add thirty grains oxide of manganese,
twenty-four grains oxide of cobalt, and forty grains cassius purple; or
to one pound of strass, twenty grains oxide of manganese, and one grain
oxide of cobalt.
F. Artificial Aquamarine. To six ounces of strass add twenty-four, grains glass of antimony, and one and a half grain oxide of cobalt.
C. Artificial Syrian Garnet. To
one thousand grains of strass add five hundred grains glass of
antimony, four grains cassius purple, and four grains oxide of
manganese.
Messrs. Bouillette, Hyrclin & Co., Rue St. waye; Savany & Mosbach, Rue Vaucauson, in Paris; and Henrys & Co.,
of London, have contributed to the great London Exhibition, in 1851, a
great display of their manufactures in artificial stones, such as
diamonds, .emeralds, sapphires, and pearls. The latter were
particularly brought to perfection by Mr. Constant Vales, Rue St.
Martin,' Paris, as the imitation pearls by that gentleman were superior
to any thing the
