A History of the Thermos

The Thermos is used mainly to keep the temperature of a liquid, either low or high. With this device we can easily enjoy a cup of coffee, tea or any other hot drink anytime and anywhere. For years, it is one of the most important devices in homes worldwide.

A bit of History

The “Vacuum flask” was invented in 1892 by Scottish chemist Sir James Dewar. Dewar was a chemist physicist best known for his work with the phenomena related to low temperatures. He studied at Edinburgh University and has lectured at Cambridge and Royal Institution of Great Britain.

How Does a Thermos Work?

Dewar invented the vacuum flask or thermos as a container for help in dealing with liquefied gas. The device itself consists of two vials, one located inside the other, separated by a vacuum. The void significantly reduces heat transfer, thus preventing a change in temperature.

The walls are generally made of glass, because it is a poor conductor of heat. Its surfaces are usually lined with a reflective metal to minimize heat transfer by radiation. The metal used by Dewar was silver, but aluminium can be used as well.

The whole fragile flask rests on a spring that is designed to absorb the impact and placed in a plastic or metal container (air between the flask and the container provides additional insulation). Even if Dewar invented something so special, he did not patent his discovery and others have thought about its value.

Commercial Start Up

The themos was not manufactured for commercial use until 1904, when two German glass blowers formed Thermos GmbH. The two then held a competition in 1907 to rename the “vacuum flask”. A resident of Munich came up with the idea of ​​”thermos” (which comes from the Greek word “Thermal”, meaning “hot”). Although Dewar sued the two Germans he had no succes. Because they patented his invention, the Thermos company was enriched. The increasing popularity of the device among ordinary people motivated the name “thermos” to be used by everyone.


In 1907, Thermos GmbH. sold the rights to the trademark “Thermos” to three independent companies: “The American Thermos Bottle Company” in New York, USA, “Thermos Limited” in Tottenham, UK and “Canadian Thermos Bottle Co. Ltd. in Montreal, Canada.

In 1909, the exhibition “Alaska Yukon Pacific” thermos became the grand prize winner, thanks to its revolutionary and innovative idea. In 1923, the company introduced Thermos Jumbo Jug, which was essentially a large insulated food storage jar.


In 1939, Thermos has played an important role in World War II, since British military forces had in their fighting equipment. In the same period, the thermos was used in atomic energy laboratories.

In 1957, the popularity of the product reaches the highest levels, and since that time it has been known worldwide. In the same period it was used to transport different types of materials such as insulin, tissues and blood plasma.

Nowadays Thermos

Today, there are many types of thermoses from plastic to metal and glass models. Generally, all these have hollow walls. By using vacuum to isolate the heat transfer by convection or conduction, the heat loss can be prevented.  The  type of opening and the use of plastics as a plug designed to maintain vacuum are also important features for a thermos.


Depending on the model, a boiler may assist in keeping hot liquids up to 24 hours.

Thermos is not only used to store drinks, but for the transport of some items such as nitrogen and oxygen or expensive and important elements such as liquid helium.

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