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Vacuum bottle (also known as dewar, Dewar or hot water bottle) is a kind of insulated storage container, which can greatly prolong the time when its content is kept higher or lower than the ambient temperature around the flask. The vacuum flask, invented by Sir James Dewar in 1892, consists of two flasks, which are placed on each other and connected at the neck. The gap between the two flasks partially empties the air, forming a near vacuum, which significantly reduces the heat transfer through conduction or convection.

Domestic thermos bottles can keep drinks hot or cold for a long time and are used for many purposes in industry.

The vacuum bottle was designed and invented by Scottish scientist Sir James Dewar in 1899 as a result of his research in the field of cryogenic technology. It is sometimes called Dewar bottle in his name. In the experiment of determining the specific heat of palladium, Dewar made a brass cavity and sealed it in another cavity to keep palladium at the required temperature. He emptied the air between the two chambers, creating a partial vacuum to keep the temperature of the contents stable. Because of the need for this insulated container, James Dewar created the thermos bottle, which became an important tool for chemical experiments and a common household item. Later, new materials such as glass and aluminum were used to develop flasks. However, Dewar refused to patent his invention.

Dewar's design quickly turned into a commercial product in 1904, when two German glass blowers (Reinhold burger and Albert Aschenbrenner) discovered that it could be used to keep cold drinks cool while warm drinks stay warm. The design of the Dewar bottle has never been patented, but the German who found that the product has commercial use renamed it "thermos", and then asked to protect the rights and trade names of the commercial product. Dewar lost out to the company in a later attempt to claim an invention right. Gustav Robert paalen, an inventor and businessman in Vienna, has greatly improved the manufacturing and performance of thermos bottles. He has designed a variety of household types. He has also obtained patents and widely distributed them through Thermos Bottle Companies in the United States and the United States. Canada. After the term "thermos" became a household name for this kind of liquid container, it later became a general trademark. Vacuum flasks were then used in many different types of scientific experiments, and commercial "thermos" were transformed into a common object. "Thermos" is still a registered trademark in some countries, but it has become a colloquial pronoun for vacuum bottles in general, so it was declared as a general trademark of "thermos" by the United States Court in 1963. But there are other thermos bottles.

After German glassblowers determined the commercial use of the dewar, the technology was sold to thermos, which used it to mass produce household vacuum bottles. Over time, the company has expanded the size, shape and materials of these consumer products, mainly for carrying coffee on the road and carrying liquids on camping to keep it hot or cold. Eventually, other manufacturers produced similar products for consumers to use.