Examination of various Ores. 529 
we apply fulphur to this compound, it will diffolve the 
one, and leave the other ; as, if gold and filver be com- 
bined, if we reduce the mafs to fine particles, and mix 
them with fulphur, and throw them into a crucible, 
heated white hot, and afterwards melt the whole mafs, 
the filver will combine with the fulphur, and the gold 
will fall to the bottom of the veflel. This being the cafe, 
we doubted whether this ore contains the gold in its me- 
tallic form, only mechanically mixed with the pyrites ; 
or combined with the fulphur by means of the iron t 
and therefore fubjecfied a fpecimen to „ examination, in 
which we could not difcover, even by the help of a mi- 
crofcope, any particle of native gold. 
exp. 1. We powdered one hundred grains of this ore* 
and boiled it in nitrous acid diluted with water; a folu- 
tion took place with effervefcence. Having digefted 
them together, till the whole foluble part was taken up, 
and poured off the folution, and made a precipitation by 
fixed vegetable alkali, the precipitate appeared to be iron* 
Having wafhed the remaining part with water, and ex- 
pofed it in a glafs matrafs in fand, to nearly a red heat, a 
very fmall portion of fulphur fublimed ; the remainder 
was quartzofe fand, with particles of gold, which were 
fimilar in figure, though fmall, to the particles of gold 
found native in veins mixed with various matrixes, and 
4 not 
