The Dewar flasks that we use for storage of cryogenic fluids such as liquid nitrogen, oxygen, and helium, and which known outside the laboratory as "thermos bottles" were invented by James Dewar, who was the first person to liquefy hydrogen, and was nearly first in the nineteenth century races to liquefy all of the other gases. While the physicists would like to claim that his contribution of The Flask was physics, chemists point out that he was educated (at Edinburgh) as a chemist, and to his (literally) "nuts and bolts" early models for the structure of benzene, one of which is still known as "Dewar benzene". Not only was Dewar an outstanding physical chemist (the best of all possible combinations), but was also famous for his popular lectures at the Royal Institution, continuing the tradition of his great predecessor in that role, Michael Faraday. Robert Soulen's Physics Today article includes pages from Dewar's laboratory notebook, drawings of his benzene models, a painting of his Royal Institute lecture at which he demonstrated the liquefaction of hydrogen, and a wonderful photograph of the scientist in his laboratory, taken with film so slow that the subject had to hold a pose for several seconds while the shutter was open.
Robert J. Soulen