The aluminum revolution
Aluminum, the third most abundant element in the earths crustand
its most plentiful metalis made from bauxite, a reddish-brown rock
discovered in Les Baux, France, in 1821. But it wasnt until 1886
that chemists finally discovered an economical way to separate pure aluminum
from its ore. Two years later, on Thanksgiving Day, a pilot plant in Pittsburgh
introduced the first commercial aluminum.
As predicted, the commercialization of this light, lustrous and non-rusting
metal has revolutionized the world. Today, aluminum is used to make everything
from aircraft to art, buildings, power lines and packaging.
The path to progress
More than 7,000 years ago, Persians made their strongest
pottery out of clay containing aluminum oxide. Three millennia later,
ancient Egyptians were using other aluminum compounds in medicines, dyes
and cosmetics. But because aluminum has a high affinity for oxygen and
never occurs in its metallic form in nature, it proved difficult to isolate.
In 1808, Sir Humphry Davy gave aluminum its name. In 1825, the Danish
chemist Hans Christian Oersted finally produced a samplealbeit very
impureusing heat and a potassium-based mixture. Over the next 20
years, Friedrich Wöhler, a German chemist, improved this process
by using metallic potassium.
The Paris debut
Henri Sainte-Claire Deville of France substituted potassium with less
expensive sodium in 1854 and was able to create enough aluminum for display
at the Paris Exposition of 1855. Billed as "silver from clay,"
aluminum bars were shown alongside Frances crown jewels. The juxtaposition
was fitting: rubies, emeralds and sapphires consist mainly of crystalline
At that time, pure aluminum was valued at $115 per poundmore expensive
than gold. Napoleon III proudly displayed aluminum cutlery at his state
banquets, commissioned aluminum equipment for his military and even had
an aluminum and gold baby rattle made for his son.
In 1886, Charles Martin Hall of the United States and Paul L.T. Héroult
of Franceboth age 22independently discovered the way to produce
aluminum economically. Hall, under the initial direction of his Oberlin
College professor, Frank Fanning Jewett, developed a method for "reducing"
aluminum oxide, called alumina, to pure aluminum by electrolysis. In the
electrolytic cell, alumina is dissolved in molten cryolite. A strong electric
current passes through the solution and removes the oxygen, leaving deposits
of nearly pure aluminum on the bottom of the bath. These deposits are
siphoned off and cast into pigs. This method is still used today.