Liquid oxygenIn 1877, Louis-Paul Cailletet (1832-1913) became the first to liquefy oxygen. Shortly after, he also was first to liquefy nitrogen, hydrogen, nitrogen dioxide, carbon monoxide, and acetylene. Cailletet realized that the failure of others to liquefy the permanent gases, even under enormous pressures, was explained by Thomas Andrews's concept of critical temperature. He succeeded in producing liquid oxygen by allowing the cold, compressed gas to expand, depending on the effect discovered by Joule and Thomson, that cooled the gas to below its critical temperature. In later experiments he liquefied nitrogen and air. Raoul Pictet, working independently, used a similar technique. He also invented the altimeter and the high-pressure manometer.Image: Cailletet's Liquefier. |
