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Sir James Dewar ( ; 20 September 1842 – 27 March 1923) was a Scottish chemist and physicist. He is best known for his invention of the vacuum flask, which he used in conjunction for his research into the liquefaction of gases. He also studied atomic and molecular spectroscopy, working in these fields for more than 25 years. Dewar was nominated for the Nobel Prize 8 times — 5 times in Physics and 3 times in Chemistry — but he was never so honoured.
In 1867, Dewar described several chemical formulas for benzene, which were published in 1869.Dewar, James (1869) "On the oxidation of phenyl alcohol, and a mechanical arrangement adapted to illustrate structure in the non-saturated hydrocarbons," Proceedings of the Royal Society of Edinburgh 6: 82–86. One of the formulae, which does not represent benzene correctly and was not advocated by Dewar, is sometimes still referred to as Dewar benzene.Baker and Rouvray, Journal of Chemical Education, 1978, vol. 55, p. 645. In 1869, he was elected a Fellow of the Royal Society of Edinburgh, after being nominated by his former mentor, Lyon Playfair. His scientific work covers a wide field – his earlier papers cover topics including organic chemistry, hydrogen and its physical constants, high-temperature research, the temperature of the Sun and the electric spark, spectrophotometry, and the chemistry of the electric arc.
With Professor J. G. McKendrick, of the University of Glasgow, he investigated the physiological action of light and examined the changes that take place in the electrical condition of the retina under its influence. With Professor G. D. Liveing, one of his colleagues at the University of Cambridge, he began in 1878 a long series of spectroscopic observations, the latter of which were devoted to the spectroscopic examination of various gaseous elements separated from atmospheric air under extremely cold conditions. He also joined Professor J. A. Fleming, of University College London, in the investigation of the electrical behaviour of substances cooled to very low temperatures.
His name is most widely known in connection with his work on the liquefaction of the so-called permanent gases and his research at temperatures approaching absolute zero. His interest in this branch of physics and chemistry dates back at least as far as 1874, when he discussed the "Latent Heat of Liquid Gases" before the British Association. In 1878, he devoted a Friday evening lecture at the Royal Institution to the then-recent work of Louis Paul Cailletet and Raoul Pictet, and exhibited for the first time in Great Britain the working of the Cailletet apparatus. Six years later, again at the Royal Institution, he described the research of Zygmunt Florenty Wróblewski and Karol Olszewski, and illustrated for the first time in public the liquefaction of oxygen and air. Soon afterward, he built a machine from which the liquefied gas could be drawn off through a valve for use as a cooling agent, before using the liquid oxygen in research work related to meteorites; about the same time, he also obtained oxygen in the solid state. By 1891, he had designed and built, at the Royal Institution, machinery which yielded liquid oxygen in industrial quantities, and towards the end of that year, he showed that magnets strongly attract both liquid oxygen and liquid ozone. Around 1892, the idea occurred to him of using vacuum-jacketed vessels for the storage of liquid gases – the Dewar flask (otherwise known as a Thermos or vacuum flask) – the invention for which he became most famous. The vacuum flask was so efficient at keeping heat out, it was found possible to preserve liquids for comparatively long periods without the need for refrigeration, making examination of their optical properties possible. Dewar did not profit from the widespread adoption of his vacuum flask – he lost a court case against Thermos concerning the patent for his invention. Although he was recognised as its inventor, there was no way for him to prevent Thermos from using his design since he did not patent his invention.
His next project was to experiment with a high-pressure hydrogen jet by which low temperatures were realised through the Joule–Thomson effect, and the successful results he obtained led him to build a large regenerative cooling refrigerating machine at the Royal Institution. Using this machine in 1898, liquid hydrogen was collected for the first time, solid hydrogen following in 1899. He tried to liquefy the last remaining gas, helium, which condenses into a liquid at −268.9 °C, but owing to a number of factors, including a short supply of helium, Dewar was preceded by Heike Kamerlingh Onnes as the first person to produce liquid helium, in 1908. Onnes would later be awarded the Nobel Prize in Physics for his research into the properties of matter at low temperatures – Dewar was nominated several times, but never succeeded in winning the Nobel Prize.
In 1905, he and J. A. Fleming began to investigate the gas-absorbing powers of charcoal when cooled to low temperatures and applied his research into the creation of a high vacuum, which was used for further experiments in atomic physics. Dewar continued his research work into the properties of elements at low temperatures, specifically low-temperature calorimetry, until the outbreak of World War I. The Royal Institution laboratories lost a number of staff to the war effort, both in fighting and scientific roles, and after the war, Dewar had little interest in restarting the serious research work that had gone on before the war. Shortages of scholars necessarily compounded the problems. His research during and after the war mainly involved investigating surface tension in soap bubbles and the detection of infrared radiation in the atmosphere, rather than further work into the properties of matter at low temperatures.
Dewar's nephew, Dr. Thomas William Dewar FRSE, was an amateur artist who painted a portrait of Sir James Dewar. He is presumably also the same Thomas William Dewar who was mentioned as the executor in James Dewar's will, ultimately replaced "unopposed" by Dewar's wife.Sir James Dewar 1842-1923: A Ruthless Chemist, by Sir J S Rawlinson.
He was President of the Society of Chemical Industry from 1887-88.
In 1904, he became the first British subject to receive the Lavoisier Medal of the French Academy of Sciences, and in 1906, he was the first to be awarded the Matteucci Medal of the Italian Society of Sciences. He was knighted in 1904 and awarded the Gunning Victoria Jubilee Prize for 1900–1904 by the Royal Society of Edinburgh, and in 1908, he was awarded the Albert Medal of The Society of Arts. A lunar crater was named in his honour.
A street within the Kings Buildings complex of the University of Edinburgh was named in memory of Dewar in the early 21st century.
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