AND OTHER METALS FROM PYRITES. 101 
other method ; but there salt costs from 10s. to 15s. per ton, 
whilst here it is seldom —e than £3. There scrap iron is cheap, 
here if consumed in any quantity it would be very expensive, . 
whilst inland carriage oe d immensely add to the cost of both. 
Again, in Great Britain the sulphur m the ores being for 
the manufacture of sulphuric acid, pays the whole or the 
greater part of the mining and carriage and the whole cost of 
the preliminary ste 8 a and sone ing, oeware! the residual 
oxide of iron free from copper and sulphur nearly of the value 
of hematite for fettling puddling furnaces ; hide both would be 
ueless. 
With regard to Claudet’s process for extracting the small 
aman of gold and silver obtained in solution —— with the 
ipi ry small cont 
ictorian etnies appointed to inquire into the treatment of 
pyrites, and others, I may note that this is only the additional 
cost of extracting those metals beyond that incurred in ex 
ing the copper. It is only applicable to ores scviisibtials minute 
quantities of gold, and besides it is requisite that the whole of 
the copper be in solution as cupric chloride, as otherwise cuprous 
iodide is precipitated. As the formation of cupric chloride 
involves the use of more salt and its precipitation of more iron 
than cuprous chloride, the process has been abandoned in many 
ere where tried. 
As the Soenaatidn of sulphate of copper during the calcination 
S) a is — to take place in two stages, oe by 
equa 
uS. + 30 = CuO. + ~~ and 
3Cu O. + S80,— CuSO OFC 
I tried whether the addition of successive tet of raw ore 
would not gradually convert the greater part of the copper into 
A ; 
PY: _ : 
sa a : this was then dried, and the copper present as oxide was 
dissolved by dilute hydrochloric acid, and its amount determined. 
ee ual to salts r cen ton copper. 
vasa 
sweet at a dull-red heat oe a small muffle, which took about an 
= recreate glee ead opoe inder was again in made up to 
es grs. with nvr , 40 grs. raw pyrites — and 
4 
