It would be more correct to say that Sir James Dewar invented the vacuum flask (in 1892). Thermos is a trade name used by the two German glassblowers (Reinhold Burger and Albert Aschenbrenner) who discovered that the vacuum flask could be used to keep cold drinks cold and warm drinks warm. Burger and Aschenbrenner founded the Thermos company in 1904. Dewar never patented his invention, and later lost a court case to Thermos.
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