James Dewar: Pioneer of Low-Temperature Physics
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 developed to store liquefied gases during his groundbreaking research into the liquefaction of gases and low-temperature physics.
Early Life and Education
Dewar was born in Kincardine, Perthshire (now in Fife) in 1842, the youngest of six boys born to Ann Dewar and Thomas Dewar, a vintner. He attended Kincardine Parish School and then Dollar Academy. After his parents died when he was fifteen, he pursued higher education at the University of Edinburgh, where he studied chemistry under Lyon Playfair (later Baron Playfair) and became Playfair’s personal assistant. He later studied under August Kekulé at Ghent University.
Career and Achievements
In 1875, Dewar was elected Jacksonian professor of natural experimental philosophy at the University of Cambridge and became a member of Peterhouse. Two years later, in 1877, he replaced Dr. John Hall Gladstone as Fullerian Professor of Chemistry at the Royal Institution, a position that anchored his research for decades. His scientific interests ranged widely across organic chemistry, hydrogen, high-temperature research, spectrophotometry, and the chemistry of the electric arc.
Dewar collaborated extensively with other scientists. With Professor J. G. McKendrick of the University of Glasgow, he investigated the physiological action of light on the retina. Beginning in 1878, he conducted a long series of spectroscopic observations with Professor G. D. Liveing of Cambridge, focusing on gaseous elements separated from atmospheric air under extremely cold conditions. He also worked with Professor J. A. Fleming of University College London on the electrical behaviour of substances cooled to very low temperatures.
In 1867, Dewar described several chemical formulas for benzene, which were published in 1869. One formula, now called Dewar benzene, does not represent benzene correctly and was not advocated by Dewar himself, yet it retained his name. He was elected a Fellow of the Royal Society of Edinburgh in 1869, nominated by his former mentor Lyon Playfair.
Beyond his academic roles, Dewar served as president of the Society of Chemical Industry (1887–88), President of the Chemical Society (1897), and President of the British Association for the Advancement of Science (1902). He also served on the Royal Commission examining London’s water supply (1893–1894) and on the Committee on Explosives, where he and Frederick Augustus Abel developed cordite, a smokeless gunpowder alternative.
Notable Events and Milestones
Dewar’s interest in liquefying gases dates to at least 1874, when he discussed the latent heat of liquid gases before the British Association. In 1878, he delivered a Friday evening lecture at the Royal Institution on the work of Louis Paul Cailletet and Raoul Pictet, exhibiting the Cailletet apparatus for the first time in Great Britain. Six years later, he described the research of Zygmunt Florenty Wróblewski and Karol Olszewski and demonstrated the liquefaction of oxygen and air publicly for the first time.
By 1891, Dewar had designed and built machinery at the Royal Institution that produced liquid oxygen in industrial quantities. That year, he demonstrated that magnets strongly attract both liquid oxygen and liquid ozone. Around 1892, he conceived the vacuum-jacketed vessel for storing liquid gases—the Dewar flask, later known as the Thermos or vacuum flask. This invention proved remarkably efficient at preserving liquids for extended periods without refrigeration, enabling the study of their optical properties.
In 1898, using a high-pressure hydrogen jet based on the Joule–Thomson effect, Dewar collected liquid hydrogen for the first time; solid hydrogen followed in 1899. He attempted to liquefy helium but was preceded by Heike Kamerlingh Onnes, who produced liquid helium in 1908. Despite his pioneering work, Dewar lost a patent court case against Thermos and never profited from his vacuum flask invention, as he had failed to patent it.
Awards and Honors
Dewar was nominated for the Nobel Prize eight times—five times in Physics and three times in Chemistry—but never received the award. His scientific contributions earned him recognition through his election to the Royal Society of Edinburgh and his presidency of major scientific organizations, yet the Nobel Prize eluded him despite his transformative work in low-temperature physics.
Additional Resources
For further information about Dewar’s life and scientific legacy, readers can consult biographical entries in Wikipedia and other scientific archives. His work on liquefied gases and the vacuum flask remains foundational to modern cryogenics and laboratory practice.
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