536 Dr. forbyce and Mr. alchorne’s 'Experiments. 
phur in this compound, as filver combines with fulphur 
in its metallic form, without lofing its inflammable air. 
Fifty Troy grains of this compound was powdered with 
difficulty, from its toughnefs, and boiled in nitrous 
acid diluted with water; it difl'olved with difficulty, leav- 
ing a very fmall quantity of a light blackifli powder, 
certainly not nearly a grain in weight. 
It appears,, therefore, that the fmall portion of fulphur- 
contained in the vitreous ore may have been decompofed 
by the nitrous acid, and the alkali, or the heat, in the 
former procefles; and we may conclude, that vitreous fil- 
ver ore is a compound of filver and fulphur, and when 
pure, that it contains between ninety-two and ninety- 
three grains of filver in one hundred. 
