248 ON THE GEOLOGY AND STATISTICS 
The copper is enclosed between a hard blackish coloured 
slaty quartzy rock. It is not raised here, as in other places, 
by mining, shafts, and levels, but is quarried out, so as to 
leave a great open excavation. 
The ores found are, the sulphuret of copper, the mala- 
chite or green and blue carbonate of copper, native copper 
in small quantities, and sulphate of copper. 
The first operation in preparing the metal is, to roast 
the sulphuret of copper in kilns constructed for the pur- 
pose ; and, by condensing the fumes, sulphur is collected 
in great quantities. It requires six months to complete this 
operation. The sulphur taken out of the chambers where 
it has been condensed, is melted, cast into moulds, and 
then sent off to the manufactories of gunpowder. 
During the action of roasting, the copper-ore, in the state 
of the bisulphuret of copper, loses an atom of its sulphur, 
and becomes the protosulphuret, or, as the workmen call 
it, the regule. It gathers from all parts, of any given lump 
of ore, into a sort of nucleus, its particles, of course, having 
actually changed their place. This may be considered as 
rather a remarkable fact, that, at a heat below fluidity, the 
particles of the metal diffused through the rocky substance 
should change their place. 
The purest copper-ore, however, is the sulphate, con- 
taining 50 per cent, of pure metal. It is found in solution 
at the bottom of the mine, and is obtained by precipitating 
the metal from a solution of sulphate of copper by means 
of iron. 
From the exhaustion of the rich copper^ ore in the Paris 
Mountain mine, recourse is now had to extract that metal 
from much of the ore which used formerly to be thrown 
away. This waste copper-ore is the protosulphuret of cop- 
per, containing a large portion of sulphiu'et of iron, which, 
from the affinity of the latter for sulphur, it bccom(?s a diffi- 
