Liquid oxygen is the liquid form of oxygen. It has a pale blue color and is strongly paramagnetic. Liquid oxygen has a density of 1140 kg/m³ and is moderately cryogenic (freezing point: −219 °C, boiling point: −183 °C). In commerce, liquid oxygen is classified as an industrial gas and is widely used for industrial and medical purposes. Liquid oxygen is obtained from the oxygen found naturally in air by fractional distillation.