James Dewar
James Dewar - A Famous Scottish Physicist & Chemist
James Dewar (1842 - 1923) James Dewar's career started at the University of Edinburgh, continued at Ghent. He became a professor at Cambridge in 1875 and in 1877 at the Royal Institution in London. He was one of the first to study the properties of matter at temperatures sensibly approaching absolute zero, and correctly surmised that the new phenomena would occur at those temperatures . He was the first man to demonstrate in public the liquefaction of oxygen. In particular, he liquefied gases by reducing their temperature until they condensed, and in 1898 he was the first to liquefy hydrogen at -240 degrees C. He later succeeded in freezing hydrogen to a solid, as he had in 1886 solidified oxygen. He also, with Frederic Abel, invented cordite. He was knighted in 1904.
Dewar Flask Liquids with very low boiling points are difficult to keep for experimental purposes, boiling violently away even at the freezing point of water. To overcome this difficulty Dewar invented the vacuum flask that bears his name. It consists of a double-walled glass container, with the inner surfaces of the walls silvered, and the space between exhausted to a high vacuum. The substance contained in the vessel is thus therally insulated from the surroundings. The evacuated space prevents the entry of heat by conduction, and the silverd walls reflect away heat transmittion by radiation. Dewar flasks have many practical uses, both domestic and industrial, one widely known commercial brand being the "Thermos" flask.
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