AND OTHER METALS FROM PYRITES. ee 2 
where it is mien. a 8 hon boiling — gases are evolved 
si viet eases the oxides from 
B are added 0 ge charge, and oh cae = haa continued until 
the whole is in a tranquil fusion, when the slags are raked off 
and ee rough copper run into moul 
e ore contains lead it is found i in the residue containing 
— go and silver ; and if pre sufficient quantity the 
be smelted, and hs pry and silver recovered by 
cu 
cupliati not aoa | in sufficient quantity to smelt, but still so much 
as to interfere wit e amalgamation, the residue is roasted, 
may be Ji age : pales of lead in caustic soda is 
mixed with sawdust or caslien, evaporated to dryness, heated 
strongly, and the chetsciiadi of soda dissolved out with water, 
‘and again rendered caustic by lime, when the lead remains as an 
insoluble residue mixed with carbon. 
The advantages of this Pa of treatment are, that the 
sulphides are entirely ggt rid of, whilst if through inattention 
in the roasting some sulphides remain, only the small proportion 
so has escaped requires to be re-roasted, instead of the whole 
eas is usually thé case. In the ernie in of copper: 
obtain 
for use wherever the ores are fou 
[One diagram.] 
