Liquid nitrogen is nitrogen at a very low temperature. It is usually produced by a process known as fractional distillation of air. At atmospheric pressure (normal pressure) nitrogen boils at −196 °C (77 K; −321 °F). Nitrogen was first made into a liquid at Jagiellonian University on 15 April 1883. Zygmunt Wróblewski and Karol Olszewski were the first scientists to liquefy nitrogen, oxygen and carbon dioxide. During World War II the production of liquid nitrogen became common. This lowered the cost to produce it. After the war new uses were found for liquid gases. Liquid nitrogen became a major gas in the US.
Liquid nitrogen has a variety of uses, as it is easy to transport, and compact.
- Cryosurgery: A Practical Manual, ed. Paola Pasquali (Berlin; Heidelberg: Springer Berlin Heidelberg, 2015), p. 7
- Ebbe Almqvist, History of Industrial Gases (New York; London: Kluwer Academic/Plenum Publishers, 2003), p. 423