The process of making or becoming liquid. Gases can be liquefied through refrigeration, pressurization, and the Joule–Thomson effect. Andrews’ work on carbon dioxide showed that to liquefy any gas, it is necessary to cool it below its critical temperature, and then to apply sufficient pressure to induce liquefaction. The liquefied gases occupy a smaller volume than gases for storage, and multicomponent mixtures can also be readily separated by the process of distillation. Solid particles can also be made into a fluid-like mass through mechanical vibration.