Antoine Laurent Lavoisier was the son of a wealthy Parisian lawyer, who hoped that his son would follow him in that profession. Although Lavoisier qualified as a lawyer in 1764 he became interested in science and he devoted much of his life to research in chemistry. His wife, Marie-Anne Pierette assisted him in his experiments. Before he was twenty-five he had lectured to the French Academy on such diverse subjects as the divining rod, hypnotism, and the construction of invalid chairs.
He was fascinated by the phenomenon of burning and, rich enough to have the best in apparatus and chemicals, he worked tirelessly to try to understand it. He was the first to clearly recognize that air consists of two gases, one of which supports combustion and the other (nitrogen) which does not. Lavoisier called this gas oxygen and recognized that it was an element.
He was one of the first chemists to recognize the importance of accurate quantitative measurements, and his accurate determination of the masses of substances formed in reactions led him to the law of conservation of mass. This was one of the earliest laws of chemistry which stated that: In a chemical reaction, atoms are neither created nor destroyed; they are merely rearranged. By careful weighing Lavoisier found for many different reactions that there was no detectable difference between the total mass of the substances reacting together and that of the substances produced. It is therefore possible to state that in any chemical reaction the total mass of the system is conserved.
Lavoisier was also one of the first to demonstrate clearly the nature of elements and compounds. In a textbook that he wrote he gave a table of elements that included many that we would recognize today. It was a great tragedy that he was arrested and guillotined during the French Revolution.