ORES. 
with nitric acid, which dissolves the silver and oxidates 
the antimony. The silver is estimated as above. The 
oxide of antimony may be reduced by fusion with 
four times its weight of black flux and a little soap 
3. Sulphuret of silver is to be treated with diluted 
nitric acid, which dissolves the silver, leaving the 
greater part of the sulphur untouched. The residuum 
is to be dried, and then the sulphur burnt off. The 
loss of weight gives the sulphur. The residuum, if any, 
is the gangue of the ore, which may be analysed by the 
rules laid down in the First Section of this Chapter. 
The silver is to be precipitated by common salt ; and 
the other metals, if any be present, may be ascertained 
as above. Part of the sulphur is always acidified. The 
acid thus formed may be precipitated by nitrat of ba 
rytes, 100 parts of the dried precipitate indicating 
about 14.5 of sulphur. 
4. Antimoniated silver ore was analysed by Klaproth 
in the following manner : 100 parts of it were boiled 
in diluted nitric acid. The residuum, washed and dried, 
was 26. These 26 were digested in nitro-muriatic 
acid. The residuum now weighed 13 (so that 13 had 
been dissolved), 12 of which were sulphur, and burnt 
away, leaving behind them one part of silica. The 
nitro-muriatic solution, when diluted largely with water, 
let fall a precipitate which weighed 13 (or 10 of pure 
antimony), and had the properties of oxide of antimony; 
for they did not evaporate till heated to redness, but at 
that temperature were dissipated in a grey smoke. 
The nitric solution was green. Common salt occa 
sioned a precipitate which weighed 87.75, equivalent 
* Selb. Kirwan's Min. i. 346. 
VoL. IV. 
145 
Chap. II. 
Sulphuret 
of silver. 
Antimoni 
ated silver 
ore.