Into each of the 500-odd warplanes produced in the U.S. last week went many times as much magnesium as the total U.S. production of this soft, silvery metal in 1914. And thereby hangs a tale:
> Of how aviation created a market for the world's least-wanted metal;
> Of how magnesium became, for a brief moment, one of the great bottlenecks of rearmament;
> Of chemical ingenuity which will not only smash the bottleneck but may soon cut the price of magnesium from 27¢ to 10¢ a lb. and make magnesium a goodly post-war competitor of both aluminum (now 15¢) and plastics.
Magnesium is everywhere. It is a vital ingredient of chlorophyll, and without it leaves would not be green. Every cubic mile of sea water contains 5,700,000 tons of it. Whole mountains of its ores lie among the Austrian Alps, the southern Appalachians, the Sierra Nevada. The far Western States are strewn with it; salt lakes are saturated with it. But until aviation came along, nobody wanted it.
In small quantities the pure metal was used for photographers' flashlights, for fireworks, for star shells, as a scavenger to remove oxygen from other metals while molten, in organic synthesis. In compounds it was used medicinally for milk of magnesia and Epsom salts. But today the fact that magnesium is only two-thirds as heavy as aluminum and less than one-fourth as heavy as steel has brought it into great demand. And from almost everything except green leaves chemists are now extracting the pure metal—some 24,000 tons this year in the U.S., twice last year's production but probably only half as much as next year's.
Mining the Ocean. A year ago magnesium was extracted from only one source, Michigan's brine wells; by only one enterprising producer, Dow Chemical Co.; and by only one method, electrolysis of molten magnesium chloride recovered from salt water. This is a chemical trick so old that it is known as a prior art and is not patentable. Last winter Trust-Buster Thurman Arnold's division of the Department of Justice sued Dow as a monopoly, but the chief reason that Dow had magnesium all to itself was that before the U.S. began rushing warplanes there was too little demand to inspire competition.
Until this spring, Dow drew all its magnesium from its inexhaustible brine wells at Midland, Mich. From these it is now extracting magnesium at the rate of 12,000 tons a year—26 times as much as in 1929. This spring Dow tapped a new source which has stirred everyone's imagination : it began mining sea water for magnesium at a great $15,000,000 plant at Freeport, Tex., which by year's end will be sucking in 12,000,000 gallons a day (enough water for a city of 120,000) and turning out 50 tons of metal—a rate of some 18,000 tons a year. This is 50% more than Dow's Michigan wells are producing, yet it would take 316 years at this rate to extract the magnesium from a single cubic mile of sea water.