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ALUMINUM. 229
the coins of that metal. Three-cent pieces, composed of
two parts sih'er and one of copper, may be used for the
same purpose :
Formula No. i. Formula No. 2.
Silver, dt parts. Silver, 6 parts.
Copper, 30 " Copper, 2 "
Zinc 10 " Brass i part.
In compounding silver solders, the silver and copper
should be first nielted, and the zinc or brass afterward
added, when they should be quickly poured, to prevent un-
due waste by oxidation of the more fusible component.
The ingot, when cold, should be rolled into a plate a little
thicker than that recommended for o-old solder.
ALUMINUM.
Symbol, Al. Atomic zveighf, 27.
Occurrence.-—Aluminum is the metallic basis of alumina,
the latter being the characteristic ingredient of common
clay. It is only within a comparatively few years that the
attention of chemists has been directed to the production
of this metal, with a view to its general introduction into
commerce and the arts. The improvements in the methods
of obtaining it, which have been more recently introduced,
have rendered its production economical and it is now sup-
;
plied in large quantities and in a greatly improved condition.
General Properties.—Commercial aluminum is never
chemically pure, and therefore displays properties varying,
more or less from the absolutely pure metal. The im-
purities usually present are iron and silicon, which vary
from I per cent, to 6 per cent.* One of the most striking
* Grade No. i, produced by the Pittsburgh Reduction Co., has of
Aluminum 99.55 per cent.. Iron 0.15 per cent., and Silicon 0.30 per cent.
This company however, for special purposes, produces a metal running
as high as 99.90 per cent. pure.
ALUMINUM. 229
the coins of that metal. Three-cent pieces, composed of
two parts sih'er and one of copper, may be used for the
same purpose :
Formula No. i. Formula No. 2.
Silver, dt parts. Silver, 6 parts.
Copper, 30 " Copper, 2 "
Zinc 10 " Brass i part.
In compounding silver solders, the silver and copper
should be first nielted, and the zinc or brass afterward
added, when they should be quickly poured, to prevent un-
due waste by oxidation of the more fusible component.
The ingot, when cold, should be rolled into a plate a little
thicker than that recommended for o-old solder.
ALUMINUM.
Symbol, Al. Atomic zveighf, 27.
Occurrence.-—Aluminum is the metallic basis of alumina,
the latter being the characteristic ingredient of common
clay. It is only within a comparatively few years that the
attention of chemists has been directed to the production
of this metal, with a view to its general introduction into
commerce and the arts. The improvements in the methods
of obtaining it, which have been more recently introduced,
have rendered its production economical and it is now sup-
;
plied in large quantities and in a greatly improved condition.
General Properties.—Commercial aluminum is never
chemically pure, and therefore displays properties varying,
more or less from the absolutely pure metal. The im-
purities usually present are iron and silicon, which vary
from I per cent, to 6 per cent.* One of the most striking
* Grade No. i, produced by the Pittsburgh Reduction Co., has of
Aluminum 99.55 per cent.. Iron 0.15 per cent., and Silicon 0.30 per cent.
This company however, for special purposes, produces a metal running
as high as 99.90 per cent. pure.
