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SIR JAMES DEWAR (1842- )

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Originally appearing in Volume V08, Page 137 of the 1911 Encyclopedia Britannica.
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SIR See also:JAMES See also:DEWAR (1842- )  , See also:British chemist and physicist, was See also:born at Kincardine-on-Forth, See also:Scotland, on the loth of See also:September 1842 . He was educated at See also:Dollar See also:Academy and See also:Edinburgh University, being at the latter first a See also:pupil, and afterwards the assistant, of See also:Lord See also:Playfair, then See also:professor of See also:chemistry; he also studied under See also:Kekule at See also:Ghent . In 1875 he was elected Jacksonian professor of natural experimental See also:philosophy at See also:Cambridge, becoming a See also:fellow of Peterhouse, and in 1877 he succeeded Dr J . H . See also:Gladstone as Fullerian professor of chemistry in the Royal Institution, See also:London . He was See also:president of the Chemical Society in 1897, and of the British Association in 1902, served on the See also:Balfour See also:Commission on London See also:Water See also:Supply (1893-1894), and as a member of the See also:Committee on See also:Explosives (1888-1891) invented See also:cordite jointly with See also:Sir See also:Frederick See also:Abel . His scientific See also:work covers a wide See also:field . Of his earlier papers, some See also:deal with questions of organic chemistry, others with See also:Graham's hydrogenium and its See also:physical constants, others with high temperatures, e.g. the temperature of the See also:sun and of the electric spark, others again with electro-See also:photometry and the chemistry of the electric arc . With Professor J . G . M'Kendrick, of See also:Glasgow, he investigated the physiological See also:action of See also:light, and examined the changes which take See also:place in the See also:electrical See also:condition of the retina under its See also:influence . With Professor G .

D . Liveing, one of his colleagues at Cambridge, he began in 1878 a See also:

long See also:series of spectroscopic observations, the later of which were devoted to the spectroscopic examination of various gaseous constituents separated from atmospheric See also:air by the aid of See also:low temperatures; and he was joined by Professor J . A . See also:Fleming, of University See also:College, London, in the investigation of the electrical behaviour of substances cooled to very low temperatures . His name is most widely known in connexion with his work on the liquefaction of the so-called permanent gases and his researches at temperatures approaching the zero of See also:absolute temperature . His See also:interest in this See also:branch of inquiry See also:dates back at least as far as 1874, when he discussed the " Latent See also:Heat of Liquid Gases " before the British Association . In 1878he devoted a See also:Friday evening lecture at the Royal Institution to the then See also:recent work of L . P . Cailletet and R . P . Pictet, and exhibited for the first See also:time in See also:Great See also:Britain the working of the Cailletet apparatus . Six years later, in the same place, he described the researches of Z .

F . Wroblewski and K . S . Olszewski, and illustrated for the first time in public the liquefaction of See also:

oxygen and air, by means of apparatus specially designed for See also:optical See also:projection so that the actions taking place might be visible to the See also:audience . Soon afterwards he constructed a See also:machine from which the liquefied See also:gas could be See also:drawn off through a See also:valve for use as a cooling See also:agent, and he showed its employment for this purpose in connexion with some researches on meteorites ; about the same time he also obtained oxygen in the solid See also:state . By.' 891 he had designed and erected at the Royal Institution an apparatus which yielded liquid oxygen by the See also:pint, and towards the end of that See also:year he showed that both liquid oxygen and liquid See also:ozone are strongly attracted by a magnet . About 1892 the See also:idea occurred to him of using vacuum-jacketed vessels for the storage of liquid gases, and so efficient did this See also:device prove in preventing the influx of See also:external heat that it is found possible not only to preserve the liquids for comparatively long periods, but also to keep them so See also:free from ebullition that examination of their optical properties becomes possible . He next experimented with a high-pressure See also:hydrogen See also:jet by which low temperatures were realized through the See also:Thomson-See also:joule effect, and the successful results thus obtained led him to build at the Royal Institution the large See also:refrigerating machine by which in 1898 hydrogen was for the first time collected in the liquid state, its solidification following in 1899 . Later he investigated the gas-absorbing See also:powers of See also:charcoal when cooled to low temperatures, and applied them to the See also:production of high vacua and to gas See also:analysis (see LIQUID GASES) . The Royal Society in 1894 bestowed the See also:Rumford See also:medal upon him for his work in the production of low temperatures, and in 1899 he became the first recipient of the Hodgkins See also:gold medal of the Smithsonian Institution, See also:Washington, for his contributions to our knowledge of the nature and properties of atmospheric air . In 1904 he was the first British subject to receive the See also:Lavoisier medal of the See also:French Academy of Sciences, and in 1906 he was the first to be awarded the See also:Matteucci medal of the See also:Italian Society of Sciences . He was knighted in 1904, and in 1908 he was awarded the See also:Albert medal of the Society of Arts .

End of Article: SIR JAMES DEWAR (1842- )
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