An American chemist who taught chemistry before becoming a research chemist and later research director for General Electric Company’s research laboratory at Schenectady, a post he held for 41 years. He proposed a theory of atomic structure and discovered how to make atomic hydrogen, and invented an atomic hydrogen blowpipe giving an extremely hot flame for welding metals. He developed a high-vacuum pump and electric discharge tubes for radio. He measured the sizes of virus molecules, which he obtained in layers one molecule thick. He is also noted for his work on surface chemistry and the molecular orientation on surfaces, the theory of adsorption catalysis, and the understanding of plasmas. He was awarded a Nobel Prize in Chemistry in 1932.