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.
Han brugte disse og lignende eksperimenter, alle påbegyndt i 1774, til at miskreditere flogiston-teorien og bevise at det stof, der blev opdaget af Priestley og Scheele, var et grundstof.