159 
ORES. 
Cun M. 
acid. The silver and gold remain ; the first in the state 
of a muriat ; the second may be dissolved by means of 
nitro-muriatic acid, and precipitated by sulphat of iron. 
The arsenic may be precipitated by concentrating the 
nitric solution, and then diluting with water. The iron 
may then be precipitated by ammonia. 
2. The sulphurated ores of arsenic may likewise be Sulphurets 
treated with diluted nitro-muriatic acid. The sulphur 
remains undissolved ; the arsenic may be precipitated 
by concentration and the affusion of water; the iron 
by ammonia. 
3. Oxide of arsenic may be dissolved ia sixteen parts 
Oxide. 
of water. The solution displays acid properties, and 
nitrat of silver and of mercury occasion precipitates in it. 
XV. Ores of Cobalt. 
1. White cobalt ore was thus analysed by Tassaert. 
Mie eod 
bakt ore. 
To ascertain the proportion of arsenic he treated the 
ore with diluted nitric acid, and obtained a complete so 
lution. Crystals of white oxide of arsenic were depo 
sited, and by repeated evaporations he separated the 
whole of the arsenic, and ascertained its weight. 
He 
then boiled a new portion of the ore with four times its 
weight of nitric acid, and thus acidified the arsenic, and 
obtained a solution. This solution was treated with 
potass, which retained the arsenic acid, and separated 
the other bodies. A precipitate of arseniat of cobalt, 
which had fallen when the nitrie solution was diluted 
with water, was treated with potass for the same rea 
son. Thé residuum, together with the precipitate oc 
casioned by the potass, was dissolved in nitric acid, and 
ammonia added in excess. Part was retained in solu 
tion by the ammonia; but part was precipitated. The