Physical Properties of Osmium

Osmium crystallises in cubes or obtuse rhombohedra of density ranging from 21.3 to 24. It is thus the most dense substance known. It is also very hard (hardness 7.5) and brittle, readily scratching glass, and in the massive form can be heated to the melting-point of zinc (419° C.) without volatilisation. At higher temperatures combustion takes place.

Osmium melts at 2200° to 2600° C., and may be distilled slowly in the electric furnace. At these high temperatures osmium can dissolve carbon. The specific heat of osmium is 0.03115.

The most intense lines in the spectrum are as follow:

Arc: 3752.69, 3782.34, 3794.08, 3963.80, 3977.39, 4112.19, 4135.96, 4173.40, 4212.06, 4261.01, 4420.64.

Spark: 2909.19, 3772.71, 4135.95, 4261.01, 4420.62.