Today in Technology History
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September 20
The inventor of the Thermos bottle, Sir James Dewar, was born exactly 160 years ago.
Dewar (pronounced DYOO-er) was born in Scotland on September 20, 1842. He was a chemist and physicist, and in the 1870s he became a professor at both Cambridge and the Royal Institution in London, keeping both positions for the rest of his life.
His most important research involved extremely cold temperatures. By the 1870s, a number of gases had been turned into liquids at temperatures near absolute zero. Dewar wanted to study the properties of these liquefied gases, but it wasn't easy to keep them cold long enough to study them.
So in 1892 Dewar invented a new kind of container that could keep his cold liquids cold. The container had two walls with a vacuum between them; the vacuum blocked heat from entering or leaving. He also coated the container with silver, so it would reflect light rather than absorb it. This double-walled vacuum container became known as the "Dewar flask."
The Dewar flask also worked on liquids at normal temperatures -- like hot and cold drinks -- so in 1904 a German company started selling the vacuum-insulated flasks as beverage containers called "Thermos" bottles.
Dewar himself had nothing to do with the Thermos company, since he never patented his invention. He did make a number of other significant contributions to science and technology, though. In the early 1890s, he became the first scientist to produce liquid oxygen, and then the first to produce solid oxygen and hydrogen. He co-invented a smokeless form of gunpowder called cordite. He did important work in the area of spectroscopy, and his research into metals at low temperatures foreshadowed the science of superconductors.
Dewar was knighted in 1904. He died in 1923, at the age of 80.
Related links:
Click here to read more about Dewar.
To better understand the science that makes the Dewar flask work, click here.
Click here to read a history of the Thermos bottle. (Please note that this site mistakenly says Dewar worked at Oxford; he was actually at Cambridge.)
Click here to read what we wrote about superconductors a few months ago.
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