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A vacuum flask or Thermos flask is a bottle that reduces heat transfer from the inside to
the outside and conversely to a minimum, and therefore keeps warm drinks warm and
refrigerated drinks cold. It was invented by Sir James Dewar, a scientist at Oxford
University in 1892. Historically vacuum flasks have been made of glass although they are now also made in metal which makes them more
durable and less prone to breakage. They comprise an outer container separated from an inner container by a vacuum; the vacuum
ensures the reduction of heat transfer.
The first vacuum flasks for commercial use were made in 1904 when a German company, Thermos GmbH was formed. "Thermos", their tradename for their flasks, remains a registered trademark.
See also Dewar flask.
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