Aluminum: Common Metal, Uncommon Past

Lockheed lounge by Marc Newson

Lockheed lounge by Marc Newson

Legacy of the Aluminum Innovation

At the time of the innovation by Hall and Héroult, the price of aluminum had dropped to less than $6 per pound, thanks in part to Hamilton Castner's 1884 improved electrolytic process to produce sodium, necessary for the Deville process. But at that price aluminum was still much too expensive to be considered for the uses for which we now know it. The company Hall helped found drove the price down to below $1 per pound by 1891, and when a lightweight aluminum crankcase for their engine enabled the Wright Brothers to take their famous first flight, the metal was about $0.30 per pound.

The story of aluminum highlights how one scientific refinement enables another, which enables another, continuing in a chain until a discovery like the Hall-Héroult process becomes inevitable. Bunsen could have successfully used electrolysis to produce aluminum over 40 years earlier; after all, Hall used the same basic power source that Bunsen had. But until Deville's chemical process proved the market and electric dynamos provided a path to commercialization, economically speaking, aluminum production seemed like folly. The fact that cryolite dissolves alumina had actually been discovered by Deville in 1859, but other details on, for example, mixture heating and construction of the reactive electrode came later.

One can only wonder what piece now missing from the world's panoply of technologies and materials will unlock the next bonanza—and those who believe there are no such riches left need only look at the fairly recent example of titanium for proof otherwise: the metal was first extracted in 1910, commercialized in 1946, and only made widespread through a process developed in 1996. From the example of aluminum's success it is important to note that Hall and Héroult are not lone geniuses, as popular as that image is. Rather, aluminum's story teaches us that success stands on the shoulders of failure, and that previously discarded ideas can lead to new discoveries—like lead into gold.

Tom Geller is a San Francisco–based freelance science and technology writer. He wishes to thank Dr. Norman C. Craig for his assistance with this article.