ALUMINUM AND ITS ALLOYS.
Symbol, Al. Equivalent, old, 13.7; new. 27.49. Specific gravity, cast, 2.46. Hammered, 2.67. Specific heat, 0.2143, Heat conductivity, 0.66 on silver scale = 100.
Melting point, 1,250° or 1,560° Fah., according to different authorities.
A shining, white, sonorous metal, having a shade between silver and platinum. It is malleable and ductile, does not oxidize when exposed to dry or moist air, and is not chemically affected by hot or cold water.
Sulphureted hydrogen gas, which so readily tarnishes silver, has no action upon this metal.
Having but one defect in its uses as a pure metal (difficulty in soldering), it enters largely as an alloy of other metals, making the baser metals more valuable in resisting oxidation, and as a good as well as cheap imitation of the precious metals.
Its power to ameliorate the condition of the alloys of copper, zinc, tin, iron, nickel, silver, gold, and platinum by portions sometimes less than a thousandth part is beautifully illustrated in the elegant articles of tableware, bric a brac, and ornamental hardware now coming upon the commercial market. Its uses in the mechanic arts in the various forms of bronzes in filling a long wanted requirement of combined ductility, strength, sonorousness, and freedom from oxidation, thus giving to its alloys a high value for articles of house hardware, carriage and harness trimmings, quick running machinery, journal bearings, propeller blades, and artillery. Piano wires made from its alloys will vibrate ten seconds longer than the best now in use.
For the kitchen and for articles for the toilet, there is no more beautiful and cleanly ware. An alloy of silver 20 and aluminum 80 parts by weight, for nautical and other instruments, is without a rival in beauty and lightness; the sea air does not tarnish it.
The aluminum-silver alloys are more valuable than pure silver for table service; its wares will not be destroyed by the constant polishing that wears out our plate, and holds an immunity from the destructive effects of the fatty and acetic acids.