Up to the present time helium has resisted all efforts to combine it with other elements.
The spectrum of helium is characterized by a strong line in the yellow (which has been shown to be double) and a dark green line.
Manufacture and Uses.— Helium is next to hydrogen in lightness among the elements, and this fact, together with its chemical inactivity and the fact that it is non-combustible, was the reason for its recent and much discussed ap plication for use in balloons.
Helium has about 92 per cent of the lifting power of hydrogen. It was Sir William Ram say who first suggested, in 1915, to Dr. Moore of the United States Bureau of Mines, the use of helium for balloons. Its buoyancy, the fact that its rate of diffusion and consequent wast age through the balloon fabric is only about one-half that of hydrogen and the freedom from fire hazard attained by its use make it an ideal balloon gas.
Certain Canadian gas wells carry approxi mately 0.3 per cent helium. Attempts to obtain helium commercially from this source were not successful, as the amount of helium present was comparatively small.
In 1917 interest in the use of helium for balloons was revived by Dr. Moore, on learning of its presence in the natural gases of Kansas. Late in the same year the Air Reduction Com pany, Inc., and the Linde Air Products Com pany each erected, for the United States gov ernment, a plant for the production of helium from the natural gas wells of Texas. These
plants started operations early in 1918 and after some experimental work produced helium on a commercial scale. Up to the time of the sign ing of the armistice, November 1918, 147,000 cubic feet of 93 per cent helium had been pre pared and was on the dock about to be loaded aboard ship for Europe. It was stated that at pre-war prices this quantity would represent a value of about $250,000,000. Needless to say such quantities could never have been obtained by the laboratory methods used in working with the small quantities of helium obtainable from various sources by the early methods de scribed in the literature.
The two above-mentioned plants in Texas are now temporarily closed, but owing to the great possibilities of the use of helium in bal loons, both for war and peace purposes, the United States government is planning to con tinue the production of helium. In addition to the two plants already built the United States government is erecting an experimental plant at Petrolia, Tex., hut at this writing this installation has not produced any helium.
The three plants referred to above are all making use of gas liquefaction processes based on the removal by liquefaction of all the gases occurring in the natural product except the helium, which passes out of the system in the gaseous state.