1 7 
Copper . 
per, silex, and sulphur were separately estimated* The 
copper is presumed to be in the metallic state in this ore 
on account of the violent evolution of nitrous gas. It is to 
be observed that by a previous trial the ore was found by 
the tests before described to be free from silver and lead* 
that is by giving no precipitate either with muriat of soda, 
or sulphat of soda* 
The variegated copper ore was assayed by the same 
eminent chemist in nearly the same manner. On account 
of its colour and its making much less effervescence with 
nitric acid, a portion of oxygen is supposed to be com- 
bined with it 
The same was assayed in the dry Way by being mixed 
with one-fourth of its Weight of charcoal and roasted, then 
mixed with a fourth of colophony or rosin, and thrice its 
weight of black flux, and well fused* The result was a 
button of copper, but 10 per cent less than the quantity 
of metal obtained in the moist way* 
The yellow haematitic copper ore and the grey vitreous 
ore from Cornwall, were analyzed by Mr* Chenevix^ 
nearly in the same manner as above described, only die 
whole solution was supersaturated with ammonia, and the 
copper separated from the ammoniated solution by boil- 
ing with potash, in the form of the black oxyd, of which 
100 parts were estimated as equal to 80 of copper* 
Ore of Silver , Copper , Iron , Antimony and Sulphur » 
Klaproth’s analysis of the Fahlerzf deserves a short no- 
tice on account of the skill with which it was managed* 
The ore was first digested repeatedly with nitric acid, 
which dissolved somewhat less than half. From the so- 
lution muriat of soda separated some silver, and it was 
then tried for lead by sulphat of soda. It was next su- 
persaturated with ammonia whereby a precipitate was left, 
which by subsequent treatment was found to consist of 
* Phil. Trans, vo!. 91. 
c 
t Essays, vpl. 1. 
