Charles Martin Hall was 22 when he figured out how to create pure globs of aluminum. Paul Héroult was 23 when he figured out how to do the same thing, using the same strategy, that same year. Hall lived in Oberlin, Ohio; Héroult lived in France. But the lure of shiny, valuable metal had captured the imagination of both.
Aluminum is one of the most plentiful substances on Earth—the most common metal found in the planet's crust. But aluminum is also a friendly element, and it's often found bound tightly to other elements. (Some jewels, like rubies and sapphires, are made mostly of aluminum oxides.) It wasn't until 1825 that anyone was able to produce even a sample of aluminum, and even that wasn't pure. So despite being incredibly plentiful, aluminum was also very rare, and therefore valued: Napoleon honored guests by setting their table places with aluminum silverware, even over gold. The Washington Monument's six-pound aluminum cap was an extravagant embellishment.
Both Hall and Héroult heard about aluminum from mentors in chemistry and both were obsessed with finding an efficient, economical process for isolating it. Hall worked out of his family's woodshed; Héroult worked out of the tannery he had inherited from his father. They both came up with the idea of using cryolite—an aluminum compound—in a solution that, when shot through with electricity, would produce pure aluminum. In relatively rural Oberlin, Hall had to gather together a passel of batteries just in order to generate electricity. But it worked.
Why did these two men hit upon the exact same idea, across an ocean? The American Chemical Society suggests that all the right information to make this discovery was converging—someone was bound to put it together:
Finding an economical process for refining aluminum was widely recognized as a prime target for inventors. Electrochemistry had begun to mature as an applied science. Large electricity-generating dynamos were being developed commercially. Interest had been aroused in the chemistry of fluorine-containing substances. Although Hall was working in a small U.S. college town, he had access to the latest in scientific thought with Jewett as his mentor.
Hall kept working to refine the process, at the company that would become Alcoa. And the price of aluminum began to drop, from $12 a pound in 1880, to $4.86 in 1888, to 78 cents in 1893 to, by the 1930s, just 20 cents a pound. The Wright Brothers used it to build the crankcase for the engine of their 1903 plane. The first aluminum foil plant opened in 1910, in Switzerland. In 1948, the foil industry figured out how to make aluminum you could cook in. And last year, the European Aluminum Foil Association estimates that it produced over a million pounds of the stuff.