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C.M. Hall

Process for the manufacture of aluminum

Eight months after graduating from Oberlin College in 1885 with a bachelor's degree in chemistry, Charles Martin Hall (1863-1914) invented an inexpensive method for the production of aluminum.

Aluminum is light and malleable but durable, a good electrical conductor, rust-resistant, and is the most abundant metal in the earth's crust; however, it does not occur naturally in pure form, and so has to be extracted from its surrounding ore. Hall realized the potential of aluminum, if only it could be extracted easily. His solution was to separate the pure aluminum from the other minerals by using electrolysis, which brings about a chemical reaction by passing an electric current through a non-metallic conductor---in this case, a molten sodium fluoride compound.

Hall was eventually granted patent #400,655 for his process (1889). In the same year, Hall found a financial backer in Alfred E. Hunt, and the two of them founded the Pittsburgh Reduction Company (later ALCOA). Up to that time, pure aluminum was considered a precious metal, used only in fine jewelry; now, aluminum began to be used in industry. Most importantly, aluminum allowed automobiles and airplanes to be lighter, more fuel-efficient, more rust-resistant, and less expensive.

The number of uses of aluminum has increased over time, and now includes items domestic (e.g., soda cans) and athletic (e.g., baseball bats). Better still---although Hall could not have foreseen this advantage---aluminum is relatively easy to recycle. Indeed, Hall's invention was and continues to be one of the most significant contributions to American industry at every level.

[Jan. 1997]

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