"...Priestley and Scheele had produced oxygen without knowing what they had laid their hands on. They "remained prisoners of the" phlogistic "categories as they came down to them." The element which was destined to upset all phlogistic views and to revolutionise chemistry remained barren in their hands. But Priestley had immediately communicated his discovery to Lavoisier in Paris, and Lavoisier, by means of this discovery, now analysed the entire phlogistic chemistry and came to the conclusion ...