1916] TREATMENT OF MOLYBDENUM ORES IN CANADA 271 
ing the metal, as is that of many other metals, such as copper and 
tungsten. The Research Laboratory of the General Electric Company 
has determined the specific gravity of ductile molybdenum before 
drawing as 10.02, whereas, after drawing, it ranges from 10.04 to 10.32. 
Molybdenum wire has a tensile strength approximately one-half that 
of hard-drawn steel piano wire or tungsten wire of corresponding size, 
and this tensile strength increases very appreciably with the fineness 
of the wire. In other words, the more the metal is worked the stronger 
it becomes. The electrical resistance of ductile molybdenum is 5.6 
microhmes per cubic centimeter of hard-drawn wire, and 4.8 for 
annealed wire, the resistivity being measured at 25° C. 
Metallic molybdenum containing carbon is grey and brittle; it is 
also very hard and scratches steel and quartz, and even the hardest file 
will not cut molybdenum alloyed with a certain proportion of carbon 
The melting point of the grey metal is much lower than that of pure 
molybdenum, and its specific gravity is also lower, ranging from 8.6 to 
8.9, according to the amount of carbon present. Pure molybdenum 
surrounded with carbon and heated to about 1,500° C., absorbs carbon 
and becomes hard; conversely, carbon-bearing molybdenum melted 
with molybdenum-dioxide is refined by the oxidation of the carbon in 
the metal. 
Pure molybdenum undergoes oxidation to an appreciable extent at 
the ordinary temperature, but it is superficially attacked at a dull red 
heat, and rapidly at 600° F., molybdenum trioxide subliming. Dilute 
acids have no effect upon it. Strong nitric acid oxidizes it, so does con- 
centrated sulphuric acid, and at the same time there are formed lower 
oxides, which are soluble in the acid with the formation of a deep blue 
colour. The halogens attack it with a formation of more or less volatile, 
variously coloured halogen and oxy-halogen compounds. 
The massive metal, on account of its less surface exposure, is less 
active toward reagents than the powder molybdenum. 
The trioxide is volatile at high temperature. 
Uses: Molybdenum is used in the form of oxides, ammonium salt 
and metal. Several tons a year are used in North America in the form 
of ammonium molybdate for the determination of phosphorus in iron 
ores, pig irons and steels, and also in the determination of phosphorus 
in fertilizers. The salt finds further use in fire-proofing certain fabrics. 
The metal is used in self-hardening steel; from five to ten per cent. is 
introduced, and the resulting steel is raised in elastic limit and tensile 
strength and possesses greater toughness in addition to the former 
property. 
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