James Dewar (1842–1923): The Master of the Ultra-Cold
James Dewar was a polymathic Scottish chemist and physicist whose work bridged the gap between Victorian-era classical chemistry and the burgeoning field of modern cryogenics. A man of immense experimental skill and a notoriously prickly temperament, Dewar is best remembered for his "race to absolute zero" and the invention of the vacuum flask—a device that remains a staple of both scientific laboratories and everyday life.
1. Biography: From Kincardine to the Royal Institution
Born on September 20, 1842, in Kincardine-on-Forth, Scotland, James Dewar was the youngest of six boys. His early education was interrupted at age ten by a severe bout of rheumatic fever, which left him unable to attend school for two years. During this convalescence, he practiced making violins, a hobby he credited with developing the extraordinary manual dexterity that later defined his experimental career.
Dewar attended Dollar Academy before enrolling at the University of Edinburgh, where he studied under the prominent chemist Lyon Playfair. He quickly rose through the academic ranks, becoming Playfair’s personal assistant and later a lecturer.
In 1875, Dewar was appointed the Jacksonian Professor of Natural Philosophy at the University of Cambridge. Two years later, he added a second prestigious title: the Fullerian Professor of Chemistry at the Royal Institution (RI) in London. He held both positions simultaneously for the rest of his life, though he performed most of his seminal research in the laboratories of the Royal Institution, following in the footsteps of Michael Faraday.
2. Major Contributions
The Liquefaction of Gases
Dewar’s most enduring scientific legacy is his work in cryogenics. In the late 19th century, scientists were racing to liquefy the "permanent gases" (oxygen, nitrogen, and hydrogen). In 1891, Dewar successfully produced liquid oxygen in industrial quantities. By 1898, he became the first person to liquefy hydrogen, reaching a temperature of only 20 degrees above absolute zero. In 1899, he succeeded in solidifying hydrogen.
The Dewar Flask (1892)
To keep these super-cooled liquids from evaporating, Dewar needed better insulation. He developed a double-walled glass vessel with a vacuum between the walls. By silvering the glass to reduce radiative heat transfer and using the vacuum to eliminate conduction and convection, he created the Dewar Flask. While he used it for scientific storage, the design was later commercialized by others as the "Thermos."
Chemical Structures: "Dewar Benzene"
Early in his career (1867), Dewar proposed several possible structures for benzene (C6H6). One of these, a bicyclic isomer, became known as Dewar Benzene. While the standard hexagonal ring (Kekulé structure) was later proven correct for benzene itself, Dewar's proposed isomer was synthesized in a laboratory in 1963, proving his structural intuition was chemically sound.
Cordite and Explosives
Collaborating with Sir Frederick Abel, Dewar co-invented cordite (1889), a smokeless propellant. This was a monumental development for the military, as it allowed for cleaner firing and better visibility on the battlefield compared to traditional gunpowder.
3. Notable Publications
Dewar was a prolific communicator, though much of his work was shared through the Proceedings of the Royal Institution and the Philosophical Magazine. Key works include:
- "The Absorption Spectra of the Alkaloids" (1870s): Early pioneering work in spectroscopy.
- "On the Liquefaction of Gases" (1878): A foundational paper detailing his early cryogenic methods.
- "The Properties of Matter at the Absolute Zero of Temperature" (1904): A summary of his findings regarding electrical resistance and magnetism in extreme cold.
- "Soap Bubbles and the Forces which Mould Them" (Later years): While often associated with C.V. Boys, Dewar published extensively on the longevity and physics of soap films.
4. Awards and Recognition
Despite his immense contributions, Dewar never received the Nobel Prize, though he was nominated several times. His accolades include:
- Fellow of the Royal Society (1877)
- Rumford Medal (1894): For his work on the properties of matter at low temperatures.
- Davy Medal (1909)
- Copley Medal (1916): The Royal Society’s highest honor.
- Knighthood (1904): Bestowed by King Edward VII.
- President of the Chemical Society (1897–1899)
5. Impact and Legacy
Dewar’s work laid the groundwork for the modern liquefied gas industry, which is vital for everything from rocket propulsion (liquid hydrogen/oxygen) to MRI machines (liquid helium).
His invention of the vacuum flask revolutionized both laboratory science and consumer culture. However, his legacy is also one of missed opportunities; because he failed to patent the vacuum flask for commercial use, he lost a fortune when the Thermos company capitalized on his invention. Furthermore, his inability to liquefy helium (a feat achieved by his rival Heike Kamerlingh Onnes in 1908) cost him the ultimate prize in physics.
6. Collaborations
- Lyon Playfair: His mentor at Edinburgh, who introduced him to the intersection of science and public policy.
- Frederick Abel: Co-developer of cordite. Their partnership involved a high-profile legal battle against Alfred Nobel over patent rights (which Dewar and Abel won).
- J.A. Fleming: Dewar collaborated with the inventor of the vacuum tube to study the electrical resistance of metals at low temperatures, discovering that resistance drops as temperature decreases—a precursor to the discovery of superconductivity.
- Henri Moissan: Dewar worked with the French chemist to liquefy fluorine for the first time in 1897.
7. Lesser-Known Facts
- The Litigious Scientist: Dewar was famously difficult to work with. He was involved in numerous priority disputes and lawsuits, most notably against Alfred Nobel and the Thermos company. His prickly nature often alienated him from his peers.
- Soap Film Obsession: In his final years at the Royal Institution, Dewar became obsessed with the physics of soap bubbles. He managed to keep a soap bubble intact for over a year by protecting it from dust and vibrations in a vacuum-sealed container.
- A Musical Ear: His childhood spent making violins gave him a lifelong love of music and acoustics. He often used musical metaphors to explain the vibrations of molecules in his lectures.
- The "Thermos" Regret: When the Thermos company won the right to the name and the patent because Dewar had not filed for a commercial patent, he reportedly became deeply bitter, viewing it as a betrayal of the "pure science" he practiced at the Royal Institution.