242 TRANSACTIONS OF THE 
product? The reverberatory furnace or even the blast 
furnace may produce a copper matte of this grade 
copper. This matte is then reduced to metal in a copper 
converter by having a blast of air blown through the 
molten stuff, the oxygen burning the iron and sulphur to 
their oxides. The copper resulting is called blister cop- 
per and assays as high as 98 to 99 per cent pure. What 
would happen if this fifty per cent chloride fume were 
melted and treated as a similar grade matte? The fact 
that the fume was entirely volatile in the process of its 
formation would suggest that it would not be consistent 
to try to reduce it to metal by blowing air through it, 
because it no doubt would in larger part revolatilize; and 
again, of course, there is neither the sulphur nor the iron 
in sufficient amount to supply the combustible matter for 
heat. What fire method does suggest itself? The chlo- 
ride of copper must be decomposed by some reagent with 
affinity for chlorine. Calcium, it is known, has such affin- 
ity but the cheap calcium salt has oxygen with it and 
simple replacement will produce copper oxide. The 
oxide of copper is readily reduced by introducing some 
carbon into the mixture. 
The reduction to metal involves the reaction: 
Cu,Cl,+Ca0+C=—CO-+CaCl,+Cu, 
Hither limestone or burned lime will answer the purpose. 
With limestone there is produced from cuprous chloride 
1.28 parts of copper for one part of limestone and from 
cupric chloride 0.64 parts of copper for one part of lime- 
stone. But 3/32 of a pound of pure carbon is needed 
per pound of copper in reducing cuprous chloride while 
3/16 parts are needed with the cupric salt. 
The reactions take place at a temperature below the 
melting point of copper. The thermo-chemical calcula- 
tions show but a reasonable amount of heat consumed. 
The reduction of the chloride to metal by this method 
therefore is perfectly feasible. 
The slag produced in the fusion method is principally 
calcium chloride. This chloride is readily fusible to a 
watery liquid. It is low in specific gravity enabling the 
copper readily to settle through it. It carries a high 
