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Havenyou ever kept icy cold liquids in a thermos? They stay colder a lotnlonger than they would in an ordinary bottle.
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nEvennbetter, have you ever kept hot coffee or cocoa piping hot in anthermos?
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nAnthermos of hot cocoa or coffee can be a beautiful thing at annighttime football game or concert under-the-stars—and we havenJames Dewar to thank for it!
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Dewarn(born on this date in 1842) was a Scottish chemist and physicist whonstudied atomic and molecular spectroscopy and the liquefaction ofngases. He needed something to store liquid gases—something thatnwould keep heat out—and the idea occurred to him to build a doublenbottle—a bottle inside a bottle—with a vacuum between the two. Wencall this invention a Dewar flask.
Dewarn(born on this date in 1842) was a Scottish chemist and physicist whonstudied atomic and molecular spectroscopy and the liquefaction ofngases. He needed something to store liquid gases—something thatnwould keep heat out—and the idea occurred to him to build a doublenbottle—a bottle inside a bottle—with a vacuum between the two. Wencall this invention a Dewar flask.n
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AnDewar flask has very reflective surfaces (mirrors) facing each othernto prevent heat from being transmitted by radiation. In other words,nthe inner surface of the outer bottle has a reflective surface, andnthe outer surface of the inner bottle also has a reflective surface.nIn between these two reflective surfaces is…nothing at all! Anvacuum is a space with almost no atoms at all—no air, nothing. Thenvacuum prevents heat being transmitted by conduction. n
AnDewar flask has very reflective surfaces (mirrors) facing each othernto prevent heat from being transmitted by radiation. In other words,nthe inner surface of the outer bottle has a reflective surface, andnthe outer surface of the inner bottle also has a reflective surface.nIn between these two reflective surfaces is…nothing at all! Anvacuum is a space with almost no atoms at all—no air, nothing. Thenvacuum prevents heat being transmitted by conduction. nn
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nThisngreat idea was exploited for commercial use by the Thermos company.nBy the way, Dewar didn’t get any money from this commercial use ofnhis idea because he failed to file a patent on it.
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nLearnnmore about a Dewar flask or Thermos from How Stuff Works.
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nLearnnmore about heat from Science Kidsnand neoK12.
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nAlsonon this date:
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nAnniversary of the first patent leather
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nAnniversary of the first Otis elevators
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