Lavoisier and the chemical revolution

Lavoisier demonstrates by careful weighing that combustion is combination with oxygen rather than release of phlogiston, establishes that mass is conserved in reactions, names oxygen and hydrogen, and publishes a systematic nomenclature and a list of elements in 1789. Chemistry becomes quantitative. He was guillotined in 1794 during the Terror; the judge is reported, probably apocryphally, to have said the Republic had no need of scientists.