The production of helium, a light, rare gas, has already become a prime requisite for aviation because it is non-inflammable and saves dirigibles from fire hazard. A new use for it is likely to be developed as the result of researches by the Department of the Interior.
Ordinary air is composed of four-fifths nitrogen and one-fifth oxygen and smaller amounts of other gases such as carbon dioxide. The oxygen content of air is the only part valuable to man in breathing. When men work in certain types of caissons, in diving suits or...
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