Sir James Dewar
Dewar, Sir James (1842-1923), a Scottish chemist and physicist. He was the first to liquefy and solidify hydrogen. Dewar was born in Scotland, and studied at Cambridge University. He was appointed professor of natural experimental philosophy at Cambridge in 1875 and was appointed to the Royal Institution, London, in 1877. He was knighted in 1904.
With Sir Frederick Abel, Dewar invented cordite, a smokeless gunpowder, in 1889. While investigating the properties of matter at low temperatures in 1898, Dewar liquefied hydrogen. The next year he solidified hydrogen at -399.82 F. (-239.9 C.). Until helium was solidified in 1908, this was the lowest temperature ever achieved. Dewar also invented the double-walled Dewar flask, forerunner of today's vacuum (thermos) bottle.