vacuum flask

The vacuum flask allows no heat to escape from or enter its contents. It has double walls with a vacuum between to prevent heat loss by conduction. Radiation is prevented by silvering the walls. The vacuum flask was invented by Scottish chemist James Dewar in about 1872.

Container for keeping things either hot or cold. It has two silvered glass walls with a vacuum between them, in a metal or plastic outer case. This design reduces heat transfer by radiation (prevented by the silvering) and conduction (prevented by the vacuum). A vacuum flask is therefore equally efficient at keeping cold liquids cold or hot liquids hot. It was invented by the British scientist James Dewar in about 1872, to store liquefied gases.