obtained metallic thorium by heating sodium with the double anhydrous
thorium potassium chloride, in presence of sodium chloride in an iron
crucible. After treating the residue with water there remains a grayish,
heavy, sparkling powder, which under the microscope appears to consist
of very small crystals. Metallic thorium is brittle and almost
infusible; the powder takes a metallic luster under pressure, is
permanent in the air at temperatures up to 120°, takes fire below a red
heat either in air or oxygen, and burns with a dazzling luster, leaving
a residue of perfectly white thoria. If heated with chlorine, bromine,
iodine, and sulphur, it combines with them with ignition. It is not
attacked by water, cold or hot. Dilute sulphuric acid occasions the
disengagement of hydrogen, especially if heated, but the metal is acted
on very slowly. Concentrated sulphuric acid with the aid of heat attacks
the metal very slightly, evolving sulphurous anhydride. Nitric acid,
strong or weak, has no sensible action. Fuming hydrochloric acid and
_aqua regia_ attack thorium readily, but the alkalies are without
action. The metal examined by the author behaves with the reagents in
question the same as did the specimens obtained by Berzelius. The mean
specific gravity of pure thorium is about 11. Hence it would seem that
the metal obtained by Chydenius must have contained much foreign matter.
The specific gravity of pure thoria is 10.2207 to 10.2198. The
equivalent and the density being known, we may calculate the atomic
volume. If we admit that the metal is equivalent to 4 atoms of hydrogen,
we obtain the value 21.1. This number coincides with the atomic volumes
of zirconium (21.7), cerium (21.1), lanthanum (22.6), and didymium
(21.5). This analogy is certainly not due to chance; it rather confirms
the opinion which I have put forward in connection with my researches on
the selenites, on certain chloro-platinates and chloro-platinites, etc.,
that the elements of the rare earths form a series of quadrivalent
metals.