Chemistry, cryogenics, and crooks.
The invention of the thermos flask
Where would we be without our trusty thermos flasks? Their ability to keep hot beverages reassuringly warm and cold drinks refreshingly chilled for hours on end is testament to an ingenious design that’s brightened wind-blasted picnics and provided comfort and convenience on the daily commute for over 100 years. Even the WFH crowd bow to the might of the thermos. Walk to the kitchen and stick the kettle on? Forget it! A thermos allows you to activate home office hermit-mode.
Whether it’s sipping on piping hot cocoa amidst a snowy landscape or enjoying a crisp, cold juice (or something stronger) at a summer festival, the thermos flask lets you enjoy your favourite beverage anytime, anywhere. And for that we have one man to thank: Scottish chemist and physicist James Dewar.
A pioneer is born
Born in Kincardine, Fife (then a part of Perthshire) in 1842, James Dewar was the youngest of six boys. His parents died when Dewar was 15, but this early tragedy didn’t cool Dewar’s academic ambitions. Educated first at Kincardine Parish School and then at Dollar Academy, he went on to study chemistry at the University of Edinburgh. Dewar even travelled to Ghent where he studied under August Kekulé, one of Europe’s foremost chemists.
James Dewar became known for his pioneering work in cryogenics but like many scientists of the day he dabbled in various fields (organic chemistry, the study of hydrogen, high-temperature research, spectrophotometry) always driven by the promise of a history-making discovery.
In 1889, he invented cordite with Sir Frederick Abel as a solution to smoke revealing a gunman’s location. In World War I cordite replaced gunpowder as a military propellant in standard rifle cartridges as well as in heavy artillery and naval guns. But it’s the invention of the vacuum flask (also known as dewar’s flask) for which he’s most famous. Unfortunately, James Dewar didn’t earn a penny from his design.
A cool discovery
Dewar’s original vessel — the grandly named “vacuum insulated goblet” — was made from glass, tin, and wax. His invention arose from the need to keep substances cold as part of his cryogenic research. To study gasses properly they had to be liquified, which involved forcing them to, and keeping them at, extremely low temperatures. An expensive process which Dewar wanted to milk by keeping the liquid gasses cold for as long as possible.
Essentially, Dewar discovered that fitting one glass flask inside a larger glass flask and creating a vacuum between the two minimised heat loss via convection. The vacuum seal slowed evaporation and kept contents cool, allowing Dewar and his colleagues more time to study liquid gas.
Dewar exhibited his vacuum flask at the Royal Institution for the first time on Christmas Day 1892. At the same time, the glassblowers who created the bottles used in Dewar’s flask had a lightbulb moment.
Around the world (and a moon landing)
Reinhold Burger and Albert Aschenbrenner were glassblowers who manufactured glass devices for the science industry. However, they quickly realised that Dewar’s glass flasks had a domestic market. Keeping liquid gasses cold is great news for scientists, but what if you simply need your tea warmer for a little longer? Appealing to ordinary, on-the-go folk, they created another vacuum flask with a metal casing and secured a patent for it.
They called their invention the ‘Thermos’ and quickly launched the product around the world. The thermos flask proved an indispensable companion to the intrepid, voyaging with Shackleton on his expedition to the South Pole and accompanying Colonel Roosevelt’s foray into the heart of the African Congo. The Wright Brothers even took a thermos flask on one of their early flights.
In 1909 Thermos won the Alaska Yukon Pacific Exposition ‘Grand Prize Award’ for their revolutionary design. James Dewar realised his error in not patenting his vacuum flask design and sued, but it was too late. Thermos was well on its way to become a multi-million, global brand and household name.
However, Dewar’s name didn’t fade into obscurity. Thanks to his knack for invention, he made many scientific breakthroughs. Dewar was the first person to create liquid hydrogen in 1898 and further low-temperature research led him to build a regenerative cooling machine and the production of solid air.
Dewar was nominated several times for the Nobel Prize, and while he missed out on one of Earth’s most prestigious awards, he did get a moon crater named after him. And what of Thermos? They say that what goes around, comes around.
By 1963 the idea of keeping hot beverages warm and cold drinks cool was so ubiquitous that Thermos lost the right to use their own name. Like aspirin, sellotape, and app store, the thermos name has become so integral to our daily lives that no one can legally claim right to it.
So, next time you’re on a picnic don’t forget to raise your thermos flask in a toast to James Dewar — the original inventor of the vacuum flask.