#chillys

If you’ve ever wondered who to thank for your ice cold drink on a hot Summer’s day, it’s this legend: James Dewar. Dewar invented the flask that many of us use daily.

Dewar never patented his invention of the flask. Instead, it was later patented and renamed by 2 German glass blowers, who set up the Thermos company, giving the Dewar flask its common name - the Thermos! *Dewar shakes fist*

The Dewar flask works by placing a smaller flask within a larger one, and sealing them at the neck. Between the 2 vessels is a gap which has had almost all of the air sucked out to create a near-vacuum.

This vacuum reduces heat transfer between the drink inside your flask, and outside world, be it hot or cold. This is because there are too few particles in the vacuum for heat energy to transfer through it by conduction or convection currents.

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