National Geographic : 1961 Feb
Glistening ingots of magnesium, 30 percent lighter than aluminum, await shipment from the Dow Chemical Company's plant in Free port. Dow mixes sea water from the Gulf of Mexico with lime to release magnesium hy droxide - milk of magnesia. Acid and electrol ysis convert the hydroxide into magnesium. Hidden in murky liquid, arms extending from the slowly revolving mechanism at the end of the catwalk concentrate the crude mag nesium. Worker takes an "ore" sample. Linked to the sea by a 57-mile ship channel, Houston ranks as one of the Nation's busiest ports. Developed at a cost of 50 million dollars, the waterway serves docks, grain elevators, oil 184 refineries, chemical plants, and steel mills.