With the help of Pierre-Simon Laplace and a guinea pig, he conducted an experiment which allowed him to conclude that respiration is a form of combustion, and that the heat produced by mammals during respiration keeps their bodies above room temperature. In 1783, Lavoisier burned hydrogen with oxygen and found that water was produced, establishing that water is not an element, but is actually a compound made from the elements hydrogen and oxygen.
In 1783 his paper, Reflections on Phlogiston, marked the beginning of the end for phlogiston and a triumph for Lavoisier’s oxygen theory and quantitative chemistry.
In 1789 Lavoisier published his groundbreaking Elementary Treatise on Chemistry.
Starting in 1791, Lavoisier served on the committee of the French Academy of Sciences which developed the metric system of measurement.
In 1794 Lavoisier was branded a traitor because of his involvement with taxation. He was unpopular with revolutionaries because he had supported foreign scientists, whom the revolutionaries wished to strip of their assets.
Antoine Lavoisier was sentenced to death and died by the guillotine at the age of 50 on May 8, 1794 in Paris.