Vacuum flask
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.