In 1908, Kamerlingh Onnes made helium liquid at a temperature of 4.2 K (about -269 °C). He had worked for many years to liquify this element which persisted as a gas to the lowest temperature. Using liquid air to produce liquid hydrogen and then the hydrogen to jacket the liquification apparatus, he produced about 60 cubic centimeters of liquid helium. The gas was liquefied by compressing it, cooling it below the inversion temperature and then allowing it to expand, which causes further cooling resulting in the liquefaction of some of the gas. At his cryogenic laboratory, he had previously liquefied air (1892) in large quantities, and built a large hydrogen liquefier (1906). Onnes received the Nobel Prize in 1913 for his low temperature work. Freezing Physics: Heike Kamerlingh Onnes and the Quest for Cold, by Dirk van Delft. - book suggestion.