During World War I, in 1916, Herbert Dow, founder of The Dow Chemical Company, received news of "star shells," weapons that glowed eerily as they descended over the trenches of the enemy, making them easier to attack. The critical component in these flares was magnesium, a metal that was suddenly in great demand. Dow, along with a half-dozen other U.S. firms, swiftly began manufacturing magnesium, but by 1927 Dow was the only U.S. company still in...