For soda cans.
(L. alumen, alum) The ancient Greeks and Romans used alum as an astringent and as a
mordant in dyeing. In 1761 de Morveau proposed the name alumine for the base in alum, and
Lavoisier, in 1787, thought this to be the oxide of a still undiscovered metal.
Wohler is generally credited with having isolated the metal in 1827, although an impure
form was prepared by Oersted two years earlier. In 1807, Davy proposed the name aluminum
for the metal, undiscovered at that time, and later agreed to change it to aluminum.
Shortly thereafter, the name aluminum was adopted to conform with the "ium"
ending of most elements, and this spelling is now in use elsewhere in the world.
Aluminium was also the accepted spelling in the U.S. until 1925, at which time the
American Chemical Society officially decided to use the name aluminum thereafter in their
The method of obtaining aluminum metal by the electrolysis of alumina dissolved in
cryolite was discovered in 1886 by Hall in the U.S. and at about the same time by Heroult
in France. Cryolite, a natural ore found in Greenland, is no longer widely used in
commercial production, but has been replaced by an artificial mixture of sodium, aluminum,
and calcium fluorides.
Aluminum can now be produced from clay, but the process is not economically feasible at
present. Aluminum is the most abundant metal to be found in the earth's crust (8.1%), but
is never found free in nature. In addition to the minerals mentioned above, it is found in
granite and in many other common minerals.
Pure aluminum, a silvery-white metal, possesses many desirable characteristics. It is
light, it is nonmagnetic and nonsparking, stands second among metals in the scale of
malleability, and sixth in ductility.
It is extensively used for kitchen utensils, outside building decoration, and in
thousands of industrial applications where a strong, light, easily constructed material is
Although its electrical conductivity is only about 60% that of copper, it is used in
electrical transmission lines because of its light weight. Pure aluminum is soft and lacks
strength, but it can be alloyed with small amounts of copper, magnesium, silicon,
manganese, and other elements to impart a variety of useful properties.
These alloys are of vital importance in the construction of modern aircraft and
rockets. Aluminum, evaporated in a vacuum, forms a highly reflective coating for both
visible light and radiant heat. These coatings soon form a thin layer of the protective
oxide and do not deteriorate as do silver coatings. They are used to coat telescope
mirrors and to make decorative paper, packages, toys.
The compounds of greatest importance are aluminum oxide, the sulfate, and the soluble
sulfate with potassium (alum). The oxide, alumina, occurs naturally as ruby, sapphire,
corundum, and emery, and is used in glassmaking and refractories. Synthetic ruby and
sapphire are used in lasers for producing coherent light.