UTAH ACADEMY OF SCIENCES 243 
percentage of chlorine and is an active chloridizing agent 
that can be used on a further batch of raw ore. At 
least one-half of the chlorine necessary for the volatiliza- 
tion may thus be regenerated. 
The calcium chloride slag is a very different material 
from the ordinary silicate slags dealt with in regular 
furnace methods for copper extraction. The pure chlor- 
ide melts at 780°C and boils at a temperature not much 
above the melting point of copper. Care must be taken 
to carry on the process of reduction at a temperature not 
too high because of the danger of volatilizing and decom- 
posing the chloride slag. The decomposition is fostered 
by hydrolysis of the calcium chloride in contact with the 
moisture of the gas or oil flame. 
While the chloridizing furnace requires a non-reduc- 
ing atmosphere in order to guarantee complete volatiliza- 
tion, the furnace for fume reduction requires a non- 
oxidizing atmosphere in order to prevent revolatilization 
of the chloride fume. The most satisfactory furnace to 
furnish the required conditions has yet to be determined. 
A reverberatory furnace promises satisfactory results. 
In order to avoid any mechanical dusting of the fume 
mixture, we are experimenting with a feeding device to 
introduce the mix into the reverberatory by feeders 
arranged to discharge their product just underneath the 
surface of the slag layer. The design provides for melt- 
ing the horizontal tube of fume and lime as it comes in 
contact with the slag on entering the furnace, so that the 
raw material may not come in contact at all with the 
direct flame or draught of the reverberatory. 
The best kind of refractory lining for the furnace is 
yeta question. The chloride of calcium is neither a basic 
nor acid slag in the sense in which these terms are ordin- 
arily used. The corroding action of the slag is not to be 
considered on the same principles that govern the action 
of acid and basic slag-forming and refractory substances. 
Chromite for example, which is neutral to acid and basic 
fluxes; is attacked by the chloride, while fireclay and silica 
bricks are more nearly neutral. 
The per cent recovery of metal from the chloride 
fume is quite satisfactory, above ninety percent of the 
