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No. 1087:

Today, we try to extract silver from clay. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Have you ever wondered why the English say aluMINium instead of alUminum? When Sir Humphry Davy identified the stuff in 1809 he called it alumium after its kinship to potash alum. That word soon became aluminum. Then, to get a Latin-sounding word, the English put in an extra letter I. They've called it aluMINium ever since.

Pure aluminum doesn't occur in nature. It's chemically bound to other elements. Aluminum oxide, or bauxite, is the commonest source. It's very hard to separate aluminum from oxygen. Not 'til 1845 did a German chemist isolate a pinpoint sample of aluminum.

In 1854 a French chemist, Henri Deville, invented a commercial process for extracting aluminum from bauxite. But his aluminum was still very expensive -- practically a new precious metal. Napoleon III commissioned a breastplate, spoons for banquets, and a baby rattle -- all made of aluminum.

But that was about to change: young Julia Hall entered Oberlin College in 1880. Two years later her kid brother Charles joined her. They learned about aluminum and about electricity. Charles read Deville's frustrating remark that "every clay bank is a mine of aluminum and the metal is costly as silver." On his 21st birthday in 1884, the newspaper carried an article about the 100-ounce aluminum pyramid that would form the tip of the Washington Monument. It went on display at Tiffany's before it was installed.

So Charles went to work with Julia's help. Maybe electrolysis would do what chemical separation hadn't. To do electrolysis at high temperatures, he hit on the idea of dissolving aluminum oxide in melted cryolite instead of water. Then he ran an electric current through it.

The process worked on February 23, 1886. He put a battery current through the hot mixture, and it precipitated bits of aluminum the size of marbles. Two years later Hall joined with a group to form the Pittsburgh Aluminum Company.

While Charles and Julia Hall were in their workshop, a French inventor -- Paul Heroult -- was developing the same process in France. But the most important problem facing the new industry wasn't the resulting patent conflict. It was the lack of any existing market for tons of cheap aluminum.

Finally, in 1893, aluminum teakettles appeared on the market, and the game was afoot. Gradually this cheap, lightweight metal found uses everywhere. In 1907 Charles Hall's company changed its name to The Aluminum Company of America -- Alcoa, for short.

Charles died a multimillionaire when he was only 51. He left a small chest behind at the Alcoa company. In it, on a felt base, are scattered a handful of aluminum pellets, produced in 1886 by the Halls' first success. And Alcoa rightly calls those worthless little fragments its crown jewels.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Friedel, R., Silver from Clay. American Inventions: A Chronicle of Achievements that Changed the World. New York: Barnes and Noble, 1995, pp. 63-69.

See also various encyclopedia articles about aluminum.