ALUMINUM--ITS PROPERTIES, COST, AND USES.


Aluminum is a shining, white, sonorous metal, having a shade between
silver and platinum. It is a very light metal, being lighter than glass
and only about one-fourth as heavy as silver of the same bulk. It is
very malleable and ductile, and is remarkable for its resistance to
oxidation, being unaffected by moist or dry air, or by hot or cold
water. Sulphureted hydrogen gas, which so readily tarnishes silver,
forming a black film on the surface, has no action on this metal.

Next to silica, the oxide of aluminum (alumina) forms, in combination,
the most abundant constituent of the crust of the earth (hydrated
silicate of alumina, clay).

Common alum is sulphate of alumina combined with another sulphate, as
potash, soda, etc. It is much used as a mordant in dyeing and calico
printing, also in tanning.

Aluminum is of great value in mechanical dentistry, as, in addition
to its lightness and strength, it is not affected by the presence of
sulphur in the food--as by eggs, for instance.

Dr. Fowler, of Yarmouthport, Mass., obtained patents for its combination
with vulcanite as applied to dentistry and other uses. It resists
sulphur in the process of vulcanization in a manner which renders it an
efficient and economical substitute for platinum or gold.

Aluminum is derived from the oxide alumina, which is the principal
constituent of common clay. Lavoissier, a celebrated French chemist,