Transmutation / Chemische Veraenderungen
Lavoisier discovered oxygen, oxidation and the chemical compound of water. His research refuted the phlogiston theory valid at his time
He determined the Law of Conservation of Mass in 1789:
Nothing is created, either in the operations of art or in those of nature, and it may be considered as a general principle that in every operation there exists an equal quantity of matter before and after the operation
Lavoisier was executed during the French Revolution at the guillotine on 8 May 1794.