The phlogiston theory was born around 1700 and lasted for about one hundred years. It provided for the first time a unifying approach to widely different chemical and physical phenomena and as such was adopted by the most famous European scientists, particularly the French ones. Its demise came with Lavoisier's new insights into the phenomena of chemical reactions in general and combustion in particular, as well as about the composition of air. Lavoisier's results disproved the phlogiston theory and established the applicability of the principle of mass conservation to chemical reactions.