Career
Previously it had been believed that oxygen only existed as 16O. As atomic masses of other elements were calculated on the basis of 16.0 not 16.0035, this was a significant discovery. The work, published in 1929, also led to the discovery in 1939 of heavy hydrogen (deuterium) by Harold C Urey.
Johnston was appointed assistant professor at in 1929 with plans to create a cryogenics laboratory to rival that at Berkeley, but sufficient funds were not available until 1939, boosted by federal money earmarked for war-related research, notably the Manhattan Project, for which he was a director from 1942-1946. A new building (titled War Research Building) was completed around the end of 1942 and the first liquid hydrogen was produced in February 1943.
Johnston had a reputation for working himself and his staff hard, especially under tight deadlines.
Despite, or perhaps because of these characteristics, he was admired by students and inspired great loyalty. One of his researchers, engineer Gwynne A Wright, remained with him for 16 years. He was appointed associate professor 1933-1938, then professor 1938-1954.
During this time he also saw work at the University of Göttingen, Germany (1933) and General Electric laboratories at Schenectady, New York (1937).
Johnston saw the United States Government"s decision to pursue research on a fission weapon (hydrogen bomb) as an opportunity to utilise his expertise in volume production, storage and transportation of liquid hydrogen (and deuterium). In 1952 he founded his own company H L Johnston Company Incorporated. to produce deuterium for the first "thermonuclear device" which was successfully tested at Eniwetok Atoll on 1 November 1952.
His company developed huge mobile refrigerated dewars for transporting bulk liquid hydrogen and even larger mobile plants for generating liquid hydrogen, for the United States Air Force. He remained on the staff at all this time, but with a greatly reduced presence.
In 1970 the War Research Building at was renamed Johnston Laboratory in his honour.
