was then added to the solution, and the copper was pre- 
cipitated in the usual way, by means of a bar of iron. 
Analysis of Copper Ores . 
The number of the analysis made of the different spe 
cies of copper ores is so immense, that a selection only of 
the most approved can here be given ; and a few general 
rules may be premised, which will simplify the subject. 
The analysis of ores is usually conducted in one of two 
distinct ways, the dry and the moist, each of which has its 
peculiar advantages and defects. 
In the dry way, the ores when they contain sulphur or 
arsenic (which is the case with the greater number) are 
first roasted in order to dissipate the greater part of these 
mineralizing substances. For this purpose, in analysis 
in the small way, they are mixed with about their bulk of 
charcoal powder (or better with hue saw-dust) and expos- 
ed to a low red heat on a flat tile or muffle, or any other 
convenient apparatus on which they can be thinly spread. 
The sulphur or arsenic soon begins to rise in fumes which 
should be hastened by frequent stirring, keeping the heat 
just below the point at which the ore would run and clot 
together, to prevent which is one considerable use of the 
charcoal or saw-dust. 
When no more fumes sensibly arise, and the charcoal 
is entirely burnt off, the part of the ore that remains now 
consists of the metallic portion in the state of an oxyd, 
still mixed however with a quantity of sulphur or arsenic, 
which mere roasting will not separate, and of all the earthy 
matrix that may have been originally contained. 
The ore is then fitted for the second process, which is 
that of reduction of the metallic oxyds to the reguline state. 
All that is essentially necessary to reduction is, to expose 
the oxyd to a high heat in contact with charcoal or car- 
bonaceous matter of any kind, and secluded from the con- 
tact of air. In reducing the metals volatile in heat, such 
