He used these and similar experiments, all started in 1774, to discredit the phlogiston theory and to prove that the substance discovered by Priestley and Scheele was a chemical element.
Ta kasutas seda katset ja sarnaseid katseid, mida kõiki ta alustas 1774. aastal, et flogistoniteooriat diskrediteerida ning tõestada, et Priestley ja Scheele avastatud aine on keemiline element.