Raoul Pierre PictetBorn 4 Apr 1846; died 27 Jul 1929 at age 83.Swiss chemist who was a pioneer of cryogenics. His original interest in the artificial production of ice (for refrigeration) led him to study the production of extremely low temperatures. He produced liquid oxygen, working independently of the French scientist, Louis Paul Cailletet, who is also credited with its discovery in 1877. However, Pictet used more elaborate equipment and was able to produce greater volumes of liquified gases. Pictet used a cascade method, in which he evaporated liquid sulfur dioxide to liquefy carbon dioxide, which in turn was allowed to evaporate and to cool oxygen to below its critical temperature. The oxygen could then be liquefied by pressure. This was also easier to apply to other gases. |
