270 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE  [VOL. XI 
period. The name molybdenum for many centuries, therefore, per- 
tained to graphite and molybdenite which were considered identical. 
It is interesting to note how these two were finally distinguished. 
By the action of nitric acid upon molybdenite, Scheele, in 1778, three 
years before his work on tungsten, showed that there were formed sul- 
phuric acid and a white acidic earthy substance which we term molybdic 
acid to-day. In 1779, Scheele firmly established the difference between 
the two minerals, theretofore confused, in another treaty on plumbago. 
In the Phlogiston way, the earth was considered the calx of a metal, 
and on this theory, in 1790, facts were made known regarding the first 
preparation of the metal by Hjelm, who, prompted by the current 
belief that carbon was rich in phlogiston, ignited the acid oxide of 
Scheele in a graphite crucible with carbon. The resulting gray metal 
must have contained considerable carbon. That process is commercially 
used to-day. 
Until recent years, the metal was in little demand for industrial 
purposes, and very little search was made for the ores of molybdenum. 
At the present time, however, owing to its introduction into metallurgy, 
in the form of iron molybdenum alloys, there is a considerable demand 
for such ores. They are produced, however, very irregularly and in 
small quantities. If a larger and more regular ore supply were assured, 
there is no doubt that new uses would be found for the metal, its alloys 
and salts, and the demand for the ores would increase. 
PROPERTIES AND USES. 
Physical and Chemical Properties of Molybdenum: Pure molyb- 
denum is a white metal, which is malleable, ductile, and soft enough to 
be filed and polished with ease. However, it is seldom produced in the 
pure state, and its appearance depends largely upon the method of 
production. Reduction of the oxides or sulphides of molybdenum with 
hydrogen yields molybdenum as a grey powder, which, under heat and 
pressure, may be compacted into a metallic bar that is brittle and even 
fragile. Molybdenum produced by the Alumino Thermic methods or 
by reduction in the electric furnace is a compact metal, but that pro- 
duced in the electric furnace contains carbon, and its physical properties 
differ from those of carbon-free metal. The melting point of molyb- 
denum is still in question. The United States Bureau of Standards 
has placed it at about 2,500° C., or 4,500° F. This is about 1,400° C., 
above the melting point of copper, and 740° C., above that of platinum. 
Osmium, tantalum and tungsten are the only three metals listed by the 
Bureau of Standards as having higher melting points. The specific 
gravity of molybdenum is increased appreciably by drawing or hammer- 
oe | 
a 
