1916] TREATMENT OF MOLYBDENUM ORES IN CANADA 277 
of the molybdenum ores of Canada; and as the Department at this 
later date were fully equipped to experiment on the problem of concen- 
tration, the investigation consisted for the most part in looking for a 
solution of the problems involved in preparing the ore for market. 
The Department secured large samples in carload lots which were 
shipped to the Testing Laboiatories of the Mines Branch in Ottawa. 
After much patient research work with.the more common specific 
gravity types of ore concentrating machinery, the conclusion was reached 
that concentration methods based upon specific gravity would not yield 
commercial results and therefore a solution of the problem would have 
to be looked for in other directions. 
After coming to the conclusion that the older processes of concentrat- 
ing minerals would not apply, the possibilities of separation by flotation 
were carefully looked into and for a time it was considered that the 
modern Oil Flotation Process would probably be adopted. However, 
during a laborious and detailed examination of this method, there were 
encountered certain difficulties in the application of the Oil Process 
which indicated the desirability of continuing the investigation for an 
easier method of working. This method was eventually found in what 
has been called the Water Film Flotation Process, and although com- 
mercial results were not immediately attained the process lent itself 
readily to adjustment, and as the factors governing the separation of 
molybdenite from its gauge by this method were more completely under- 
stood, a type of apparatus was gradually evolved which is at the present 
time in successful operation at the Ore Testing Laboratories of the 
Department. 
The principle upon which this method is based is the surface tension 
of water, advantage being taken of the fact that molybdenite resists 
wetting, while its associated minerals are more or less easily wetted and 
submerged. . 
The method of separating molybdenite from other minerals by 
means of projecting the ore upon a sheet of flowing water has been known 
for many years, but the first commercial application of the process on 
a large scale was made by Henry E. Wood, of Denver, Colorado, who 
patented the Wood Water Film Flotation Machine in the United States 
and Canada. 
About the time the officials of the Department had satisfied them- 
selves that water film flotation was the most desirable process for the 
separation of the majority of Canadian ores, attention was directed to 
the Wood type of apparatus, and after consultation with Mr. Wood it 
was decided to install one of his machines at the Testing Laboratories 
in Ottawa. Subsequently, certain weaknesses in the Wood machine 
