European steel men have taken to molybdenum
more than Americans. The salts of this metal can be used in dyeing and
photography.
Calcium, magnesium and aluminum, common enough in their compounds, have
only come into use as metals since the invention of the electric
furnace. Now the photographer uses magnesium powder for his flashlight
when he wants to take a picture of his friends inside the house, and the
aviator uses it when he wants to take a picture of his enemies on the
open field. The flares prepared by our Government for the war consist of
a sheet iron cylinder, four feet long and six inches thick, containing a
stick of magnesium attached to a tightly rolled silk parachute twenty
feet in diameter when expanded. The whole weighed 32 pounds. On being
dropped from the plane by pressing a button, the rush of air set
spinning a pinwheel at the bottom which ignited the magnesium stick and
detonated a charge of black powder sufficient to throw off the case and
release the parachute. The burning flare gave off a light of 320,000
candle power lasting for ten minutes as the parachute slowly descended.
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