specific Gravity , and comparative Wear of Gold. 81 
part of this Paper, that gold does not become brittle by the addi- 
tion of iron. In order, however, to ascertain what effects could 
be produced by emery,* the following experiments were made. 
EXPERIMENTS ON EMERY AND GOLD. 
Experiment r. 
One ounce of fine gold was put into a small crucible, and 
was completely covered with emery, which had been reduced 
to a fine powder. 
The gold was kept in fusion during one hour, and was fre- 
quently stirred, after which, it was poured into a mould. 
Not the smallest change, in colour, ductility, or any other 
property, was thus produced. 
Experiment it. 
About half an ounce of fine powder of emery was, several 
times, alternately moistened with olive oil and made red hot, 
after which, it was put into a crucible lined with charcoal. 
* Mr. Tennant has lately shown, (Phil. Trans, for 1802, page 400,) that emery is 
composed of alumina, silica, and iron. In one case, he obtained. 
Alumina 
Silica 
Iron 
Residuum 
80 
3 - 
4 
3 
90. 
And, from another variety, more impregnated with iron, he obtained,, 
Alumina - - 50 
Silica g 
Iron - 32 
Residuum - 4 
24 * 
MDCCCIII. 
M 
