Indigenous in great quantities only to the United States, helium soon became the nonflammable gas of choice for lighter-than-air craft. In February 1930 the federal government inaugurated a new plant seven miles south of Amarillo, Texas, where a virgin gas field of approximately fifty thousand acres was thought to lie. Not only was the mined gas about 2 percent helium, but the pressure at which it was extracted from the ground required no further compression to carry out the extraction of the helium from the gas mixture. After purifying the natural gas of its relatively high carbon dioxide content (about 0.5 percent), separation of the helium from the other elements (mainly methane, ethane, and nitrogen) was carried out immediately upon cooling the compound to -300 degrees Fahrenheit, at which helium naturally separates itself from the other liquefied gases. Shipment of the helium, whose...