Liquefaction of gases low temperatures, using, for example, turboexpanders. The liquefaction of air is used to obtain nitrogen, oxygen, and argon and other atmospheric noble gases by separating the air components by fractional distillation in a cryogenic air separation unit. Air is liquefied by the Linde process, in which air is alternately compressed, cooled, and expanded, each expansion results in a considerable reduction in temperature. With the lower temperature the molecules move more slowly and occupy less space, so the air changes phase to become liquid. Air can also be liquefied by Claude's process in which the gas is allowed to expand isentropically
Copia: Foundations of the Abundant Style 11 separate methods of using abundant subject matter. Here Erasmus uses a more dialectical approach, and typically gives a few lines of theory followed by many illustrations from classical sources. Erasmus purpose was to contribute to the existing scholarship on style. To that end, he put forth in "De Copia" that style must be abundant in order to be effective, and that the abundance consists of two primary elements: variety of expression and variety of subject matter. Variety, he says, “is so powerful in every sphere that there is absolutely nothing, however brilliant, which is not dimmed if not commended