In 1892, the Scottish scientist Sir James Dewar was involved in research in cryogenics (how materials behave at very low temperatures). As a part of this research he was working with palladium (Pd; a transition metal) which he needed to keep at a constant temperature. His solution was to use two brass flasks or chambers, one placed inside the other. The two flasks were then joined at the neck and the air between the two flasks was then partially evacuated which created a near-vacuum. This vacuum reduced heat transfer.
The Dewar Flask or the Dewar Bottle became an important tool for scientists. Dewar refused to patent his invention, which allowed other scientists to use it freely and improve upon it. In his viewpoint this was a scientific instrument.
It should be noted that Dewar was not the first scientist to use a vacuum flask. In 1881, the German chemist and physician Adolf Ferdinand Weinhold had also created a vacuum flask.
In 1904, two glassblowers in Germany discovered that the Dewar Flask could keep hot beverages hot and cold beverages cold. More importantly, they saw a commercial application for this. They held a contest to come up with a new name for this commercial product and as a result the Thermos was born. A resident of Munich, by the way, submitted the name Thermos from the Greek word therme meaning “hot.” Since there was no patent on the Dewar Flask, the German glassblowers trademarked the name and claimed the rights to the commercial product.
In 1907, the Thermos trademark rights were sold to three independent companies: Thermos Limited of Totenam, England; Canadian Thermos Bottle Co. Ltd. Of Montreal, Canada; and The American Thermos Bottle Company of Brooklyn, New York. These three companies developed the thermos bottle into a popular consumer product.
Thermos Limited of England began producing the first machine-made glass filler in 1911. During World War I, production of Thermos Limited was nearly shut down and it wasn’t until 1931 that the company resumed its production of glass fillers. During World War II, the company produced Thermos vacuum flasks for the wartime efforts. According to one report:
“Every time a thousand bombers went out on a raid, 10,000 to 12,000 Thermos vacuum flasks went with them.”
During World War II, about 98% of the output of the American Thermos Bottle Company was for the war effort, primarily for military usage and atomic energy laboratories.
Following World War II, the thermos became a popular consumer item throughout the world. New materials and new methods of manufacture have improved the basic flask.
While “Thermos” was a trademarked name, it soon became a household name. In 1963, the United States declared it to be a generalized trademark synonymous with vacuum flasks in general.
