I weighed the reactants and products of reactions in sealed glass vessels so no gas could escape, and in 1774 showed the total mass is the same at the end of every chemical change as at the start.
In 1783, with Pierre-Simon Laplace, I synthesized water by burning jets of hydrogen and oxygen in a bell jar over mercury, and showed quantitatively that water is a compound of two gases, not an element.
From 1772 to 1778 I ran combustion and calcination experiments that showed burning substances gain weight by combining with part of the air — the research that became my oxygen theory and named oxygen.
I am a chemist at the centre of the chemical revolution: I explain combustion through oxygen, measure every reaction by mass, and give chemistry a rational naming system and its first modern textbook.
