532 Dr. fordyce and' Mr. alchorne’s 
The ore has the appearance of native filver, in Italy 
particles, intermixed with a hard quartz, tinged brown 
in fome parts by iron. Twenty-five grains of the mafs, 
where the metal was in the largeft proportion, melted 
with litharge, alkali, and phlogiftic matter, and after- 
wards coppelled, yielded a globule apparently filver 
weighing two grains which, being boiled in nitrous acid 
diluted with water, left, full nine fixteenths of a grain of 
fine gold. Hence one hundred pounds of metal obtained 
from this ore, confiits of feventy-two pounds of filver, 
and twenty-eight pounds of gold. 
There is an ore of filver which is commonly called 
vitreous (miner a argent i vitrea y ox argentum vitreum). 
This ore has always been fuppofed to confilt of ful- 
phur and filver; becaufe, if we melt fulphur and filver 
together, they form a mafs which refembles it, efpecially 
in colour and malleability ; but, as we could find no ex- 
periment in any author which authorized this conjecture, 
we determined to endeavour to afcertain it by analyfis, 
Dr. hunter not refufing to fubjeCt the ore to an affay, 
although fcarce and expenfive. 
exp. v. Fifty grains of this ore broken in pieces, for 
it is too malleable to be powdered, were boiled in nitrous 
acid diluted with water; the acid diffolved the filver with 
much difficulty, and left a refiduum. The folution being 
poured 
