UTAH ACADEMY OF SCIENCES 219 
and including the present, recovery of metals from ores 
has been a wasteful process, the amounts of metal lost 
in.slags and dross and in fumes ranging from a fraction 
of a percent in the rare best instances to fifty percent 
or more in the worst cases. So great is the world’s de- 
mand for metals that the easily worked deposits are 
rapidly being exhausted and economical and conserva- 
tive treatment of the vast deposits of low grade ores is 
becoming absolutely essential. 
The history of metallurgy is that of an art and not 
of a science. To be sure the facts of metallurgy have 
contributed much to science but progress in the working 
of metals has been very largely through the efforts of 
men who knew little and cared less concerning the 
sciences. Much progress may still be expected from the 
same type of empiricists. But more and more the art of 
metallurgy is looking for guidance to the sciences of 
chemistry and physics. 
The traditional method of securing pure metals from 
ores has been to mix the ore with certain substances 
which experience had shown to be appropriate, to subject 
to heat and to obtain the metal first in a molten state 
and finally in solid form. This is the typical metal- 
lurgical process applied to all the most important metals: 
iron, copper, lead, gold, silver and tin. In the case of a 
few metals, however, the practice reaching back into 
antiquity has been to separate the metal by converting it 
into vapor and condensing the fumes. This is notably 
true of zinc and mercury. In the treatment of all the 
metals certain reagents, certain appliances and certain 
procedures, have been found best adapted to each ore. 
No one method has been developed which would free all 
the common metals which might be present in a mixed 
ore, though methods for separating metals from each 
other after they have been reduced to the metallic state, 
have been very well worked out. Temperatures suitable 
for the reduction of one metal are not suitable for an- 
other; reagents which are helpful in one case are harm- 
ful in another, etc. 
Among pyrometallurgical processes the alternative 
of converting the metals into the vapor state and con- 
