Acenturyearlier, Henry Cavendish had noted the existence of a residualgaswhenoxygenandnitrogenare removed from air, butitsimportancehadnot beenrealized.
An experiment under way at the University of Washington, led by Eric Adelberger, tests this idea using the world's most sensitive torsion balance, a souped-up version of the kit HenryCavendish, an English physicist, used to measure gravity directly for the first time in the late 18th century.