Vacuum Flask

A vacuum flask, also called a Dewar flask or known by the trademark thermos, is an insulating storage vessel that slows the rate at which its contents change temperature by minimizing heat transfer across a near-vacuum gap between two nested chambers. It was invented in 1892 by the Scottish scientist James Dewar during his research into cryogenics, when he built a chamber nested inside another with the air evacuated between them to keep materials at stable low temperatures for his experiments; Dewar deliberately did not patent his invention, which allowed other manufacturers to refine it using glass and aluminum and turn it into both a laboratory tool and an everyday household item.