3. Scratches a copper coin but is also scratched by it, being of about the same degree of hardness.
4. Not scratched by a copper coin. Does not scratch glass.
5. Scratches glass with difficulty, leaving its powder on it. Yields readily to the knife.
6. Scratches glass easily. Yields with difficulty to the knife.
7. Does not yield to the knife. Yields to the edge of a file, though with difficulty.
8, 9, 10. Harder than flint.
Specific gravity cannot well be determined without the aid of a balance, and hence its value here is not great.
As in the preceding chapter, alphabetic arrangement will be employed.
Ores of Antimony
Stibnite, Sb2S3, Sb . 71, S . 29.—[A]H = 2, G = 4.52-4.62. Of lead-gray color and metallic lustre. Consists of a large number of needle-shaped crystals. Brittle. Fuses in candle flame. In an ignition tube yields a sublimate of sulphur. On Ch. before the Bp. it is volatilized, giving antimony coating and tinges the flame pale blue.