As it was, they soon put the liquefaction and solidification of the elements to countless uses. A few of these were the cooling of their buildings by concentrated air, the use in the arts of its corrosive power and of its power of rendering most metals easily plastic, its amalgamation with other elements into an explosive matter so destructive as to supersede the use of the leomoran in earth-perforation, and the storage of their faleenas with supplies for expeditions that would take years in interstellar space. A minor use to which they put alfarene was the production of vacuums. They had long had mechanical air-pumps, that gave them the vacuums they needed for their experiments. But they now found it much easier to enclose one of these snow-stunted shrubs in an air-tight vessel of transparent irelium, and watch it absorb the air within the walls. The energy formerly spent on the making of air-pumps was saved, and devoted to some other useful purpose. What was still better was the continual experimentation on the human system carried on by means of these so easily accessible vacuums. The alfarene vacuum became the daily plaything of the Limanoran, and he took pleasure in finding out the needs of his body in it, and the length of time he could endure the pure ether. It was not long before they knew every difficulty they would be likely to encounter in crossing from star to star. The minor defects of the body were easily met after a few years’ study of them by the various scientific families. But two gave them long pause.