The name is absent

272 Science and Human Welfare

chloric acid; the chloride is dried, and then fused and elec-
trolyzed in cells where the metal rises to the top and is
skimmed off. The lightness of magnesium is amazing. A
magnesium alloy girder, which one man can handle with
ease, will support the weight of a heavy automobile.

Magnesium has about 6o per cent of the weight of alu-
minum. It sold, in 1915, for S5.00 per pound and was, until
a few years ago, a structural curiosity. Today, measured by
volume, magnesium at 22 cents a pound is cheaper than
aluminum selling at 15 cents a pound. On the average, about
a half ton of it is going into every fighting plane. After the
war, the nation’s capacity for producing this lightest of all
structural metals will be more than double the aluminum
output in 1939. Published data gave the capacity of the old
plant of the Dow Chemical Company at Freeport as 125,000
pounds per day, using a flood of 25,000 gallons per minute of
sea water. The plant has been enlarged until the original
production amounts to only a fraction of the present output.
Just try to visualize two hundred tons per day of magnesium
ingots obtained from sea water in which the concentration of
the magnesium amounts to only around ɪɪoo parts per
million. A computation of interest is that a cubic mile of sea-
water carries about 10 billion pounds of magnesium—enough
to run our 1943 war effort and similar ones for ten years.
There, in the sea, is an inexhaustible supply of industrial
material.

Magnesium is seldom used alone. Add a little aluminum
and it will gain sixfold in hardness and strength. Such a com-
mercial alloy is the exceptionally strong Dowmetal which
carries about 8 per cent aluminum with a little zinc and man-
ganese. It will be of interest to know that the war plan calls
for one billion pounds of magnesium in 1943.

But iron, composing about 5 per cent of the earth’s crust,

<<   2   3   4   5   6   7   8   >>

More intriguing information