Light Heavyweight

Magnesium, a baby among structural metals, is growing up fast. As evidence, last week hundreds of magnesium products were put on display at the International Magnesium Exposition in Washington's cavernous National Guard Armory. Two-thirds the weight of aluminum, magnesium had comparatively few uses before World War II, was produced in the U.S. only by Dow Chemical Co. (from sea water). Then production of airplanes, which made the lightness and strength of the metal a necessity for many parts, boosted magnesium output to a peak of 183,584 tons in 1943. After war's end production slumped to a piddling 5,317 tons. With new commercial uses, production is once more on the rise, reached about 106,000 tons last year. The aircraft industry is still the biggest user (29% Of U.S. output). At the exhibit was Douglas' needle-nosed Skyrocket, which has flown higher (79,494 ft.) and faster (1,238 m.p.h.) than any other airplane on record, and whose fuselage is fabricated from magnesium sheets. Other exhibits

P: An automobile with a magnesium body that weighs only 132 lbs. (v. a minimum 650 Ibs. for a steel car body). Designer K. J. Cross, managing director of Britain's Essex Aero, Ltd., believes that magnesium bodies are far superior to plastic, which take longer to fabricate. The lightness of magnesium bodies makes possible higher speeds and quicker acceleration for cars Cross hopes to have his magnesium car in production for export to the U.S some time this year. Price: around $3,400.

P: A 60-ft -long, collapsible military maintenance shelter, which resembles a Quonset hut, made of canvas on a magnesium-alloy frame. It weighs slightly more than one ton (onefourth as much as other structures of the same size and strength).

P: Magnesium skis that will not warp, dry out or lose their camber.

P: A tubular magnesium walker for crippled adults and children, which weighs less than a quart of milk.

P: Such lightweight household equipment as a portable sewing machine half as heavy as present machines; a kitchen step-stool that weighs only two pounds; a clothes-drier rack one-third as heavy as those made of wood; a 16-in. lawnmower that weighs only 25 Ibs. (plus the handle).

The exhibitors were buoyantly optimistic about magnesium's future. At 27-c- a lb., it is already cheaper by volume than aluminum (21.5-c- a lb.), can be easily welded, has a low electrical resistance and high heat conductivity, and resists weathering. And there is plenty of it. In every cubic mile of sea water, still the principal source of supply, there is an estimated 12 billion Ibs. of magnesium.

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