Dewar’s invention of the vacuum flask

In 1892, the Scottish chemist James Dewar created a double-walled container with a vacuum between the walls to store liquefied gases at extremely low temperatures. This design reduced heat transfer by blocking conduction and convection, leaving only thermal radiation as a means of heat transfer.

Public demonstration of the vacuum flask

Dewar publicly presented his invention at the Royal Institution in London on Christmas Day 1892. The original prototype is still preserved today, though Dewar never filed a patent, considering it a laboratory tool for his research, including the production of the first liquid hydrogen in 1898.

Commercialization by Reinhold Burger

In 1903, the German glassmaker Reinhold Burger patented Dewar’s design and filed the Thermos trademark in 1904. The German patent, numbered DRP 170057, was published in 1909 and described a "double-walled container enclosing an air-vacuum cavity." The name Thermos comes from the Greek word for heat.

Legal dispute over the invention

Dewar attempted to assert his rights in court but lost the case. Burger retired from Thermos GmbH shortly after 1907, according to his grandson Axel Burger, after the company was bought for 65,000 marks. The thermos bottle gained commercial success, being awarded at the World Expositions of St. Louis in 1904 and Milan in 1906.

Claims of sole invention

German sources close to the Burger family claim that their ancestor is the sole inventor of the common insulated bottle, challenging the exclusive attribution to Dewar. The dates of invention and commercialization vary, ranging from 1903 for the patent filing to 1904 for the actual commercialization under the Thermos brand. One thing remains certain: without the meeting between the scientific curiosity of a Scottish chemist and the practical sense of a German glassmaker, the modern insulated bottle would not exist.