UTAH ACADEMY OF SCIENCES 225 
in the chain of operations involved in the volatilization 
process, it is now, thanks to the Cottrell process of pre- 
cipitating fumes, probably the least uncertain step. 
Treatment of the precipitated chlorides in order to re- 
cover the separate metals has also been passed over in 
this paper. This is not because the step is not important, 
but rather because the questions involved are more those 
of practical metallurgical procedure than of theory, for 
example, what is the best type of furnace to use to avoid 
losses by revolatilization. 
