irements,
chiefly from plants installed at two lead refineries. A further
installation would make this country entirely independent of foreign
supplies if occasion required. Imports, from England and South America,
have been steadily declining, but during the war were somewhat
increased. The United States does not export bismuth so far as known.

GEOLOGIC FEATURES

The principal minerals of bismuth are bismuthinite (bismuth sulphide),
bismutite (hydrated carbonate), bismite or bismuth ocher (hydrated
oxide), and native bismuth.

The native metal and the sulphide are believed to be formed mainly as
primary minerals of igneous origin. In the deposits of New South Wales
they are found associated with molybdenite in quartz gangue, in
pipe-like deposits in granite. The oxide and the carbonate are probably
products of surface weathering. The Bolivian deposits contain the native
metal, the oxide, and the carbonate, associated with gold, silver, and
tin minerals, in one locality in slates and in another locality in
porphyry. The origin is not well known.

In the United States, the sulphide, bismuthinite, is found in the
siliceous ores of Goldfield, Nevada (p. 230), and in minor amounts in a
great number of the sulphide ores of the Cordilleran region. The ores of
the Leadville and Tintic districts (pp. 219 and 235) yield the larger
part of the United States production, the bismuth being recovered as
by-product from the electrolytic refining of the lead bullion. Large
amounts of bismuth pass out of the stacks of smelters treating other
western ores, and while it would not be cheap nor easy to save the
bismuth thus lost, it could probably be done in case of necessity.

CADMIUM ORES

ECONOMIC FEATURES

Cadmium is used in low melting-point alloys--as, for example, those
employed in automatic fire-extinguishers and electric fuses,--in the
manufacture of silverware, and in dental amalgams. During the war the
critical scarcity of tin led to experiments in the substitution of
cadmium for tin in solders and anti-friction metals. Results of some of
these experiments were promising, but the war ceased and demands for tin
decreased before the cadmium materials became widely used. Future
developments in this direction seem not unlikely. Cadmium compounds are
used as pigments, particularly as the sulphide "cadmium yellow," and to
give color and luster to glass and porcelain. Cadmium salts are also
variously used in the arts, in