of 90 per cent. of copper and 10 per cent. of aluminum. Like iron, it
does not amalgamate directly with mercury, nor is it readily alloyed
with lead, but many alloys with other metals, as copper, iron, gold,
etc., have been made with it and found to be valuable combinations.
One part of it to 100 parts of gold gives a hard, malleable alloy of
a greenish gold color, and an alloy of 3/4 iron and 1/4 aluminum does not
oxidize when exposed to a moist atmosphere. It has also been used to
form a metallic coating upon other metals, as copper, brass, and German
silver, by the electro-galvanic process. Copper has also been deposited,
by the same process, upon aluminum plates to facilitate their being
rolled very thin; for unless the metal be pure, it requires to be
annealed at each passage through the rolls, and it is found that its
flexibility is greatly increased by rolling. To avoid the bluish white
appearance, like zinc, Dr. Stevenson McAdam recommends immersing the
article made from aluminum in a heated solution of potash, which will
give a beautiful white frosted appearance, like that of frosted silver.

F.W. Gerhard obtained a patent in 1856, in England, for an improved
means of obtaining aluminum metal, and the adaptation thereof to the
manufacture of certain useful articles. Powdered fluoride of aluminum is
placed alone or in combination with other fluorides in a closed furnace,
heated to a red heat, and exposed to the action of hydrogen gas, which
is used as a reagent in the place of sodium. A reverberating furnace is
used by preference. The fluoride of aluminum is placed in shallow trays
or dishes, each dish being surrounded by clean iron filings placed in
suitable receptacles; dry hydrogen gas is forced in, and suitable entry
and exit pipes and stop-cocks are provided. The hydrogen gas, combining
with the fluoride, "forms hydrofluoric acid, which is taken up by the
iron and is thereby converted into fluoride of iron." The resulting
aluminum "remains in a metallic state in the bottom of the trays