specific Gravity , and comparative Wear of Gold. 63 
Experiment in. 
From the effects last mentioned, it was evident that manga- 
nese could be thus combined with gold; the experiment was 
therefore repeated, and the heat was continued during three 
hours, at the end of which time the crucible began to be 
melted.* 
Upon breaking the crucible, which had been suffered to cool 
in the furnace, the manganese was found to be pulverulent in 
some parts, and indurated in others. There were not any me- 
tallic globules to be seen ; and the colour varied from dark to 
pale grass green. 
The button of gold at the bottom of the crucible was uni- 
form, and externally of a pale yellowish gray colour, with a 
considerable lustre, almost equal to that of polished steel. 
On that part of the button which had been next to the bottom 
of the crucible, were some specks of pale green enamel. The 
metal possessed a small degree of ductility, although extremely 
hard, for, when placed upon an anvil, being repeatedly struck 
with a heavy hammer, the button was in some measure flattened, 
before it could be broken. 
The fracture was coarse, very spongy, and of a reddish gray 
colour; and many cavities, in the interior of the mass, were 
filled with the dark green coloured manganese. 
It has been generally observed, that metals, when combined 
with manganese, are liable to a speedy change and diminution 
of lustre, colour, &c. when exposed to the air ; but gold alloyed 
* This reduction and union of manganese with gold, seems to have been effected 
by the double affinities between oxygen, carbon, gold, and manganese ; and there is 
every reason to believe, that the above method may be advantageously employed, to 
form the alloys of the refractory metals with those of easy reduction and fusibility. 
