UTAH ACADEMY OF SCIENCES 157 
bullion by the Pattinson process depends upon the chem- 
ical theory of fractional crystallization. 
In this case the bullion is melted and upon cooling 
we have crystals of pure lead forming and separating 
from the mixed crystals of silver and lead. 
The chemical reaction between metallic gold and 
mercury form the basis for the amalgamation process for 
recovering gold from a free milling ore; that is, one in 
which the gold exists as the metal. In the recovery of the 
gold from this amalgam we use another chemical reaction, 
namely, that mercury is easily volatilized at about 360°C 
and passes off as a vapor leaving the gold in the retort. 
The mercury is condensed and used again. 
This ease of volatilization of mercury is used as a 
means of extracting mercury from its ores. These mer- 
eury ores are heated and the fumes upon cooling gives 
us metallic mercury. 
The cyanide process depends upon the chemical 
reaction of Ag and Au and cyanide in the presence of 
oxygen. 
All leaching processes are based upon the chemical 
solubilities of the metallic compounds in the solutions 
used and the recovery of these dissolved metals is again 
dependent upon the chemical properties of the respec- 
tive elements. 
The chloride volatilization process for the recovery 
of gold, silver, lead and copper from the lower grade 
oxidized ores depends upon the chemical reaction of 
these elements with chlorine. 
Lead chlorine boils at about 860°C, cuprous chloride 
at about 950°C and the chlorides of gold and silver dis- 
sociate at temperatures somewhat lower than these. 
The most important reagents are salt or sodium 
chloride and calcium chloride which melt at 805°C and 
780°C respectively, so that they are brought into inti- 
mate contact with the ore particles before the tem- 
perature of volatilization, 900-1000°C is reached. 
These statements show that every one of the pro- 
cesses mentioned are dependent upon some definite 
chemical reactions and justify the assertion that metal- 
lurgical operations are only applications of chemical 
processes. 
