The Phlogiston Theory

The Phlogiston Theory


The Phlogiston Theory was proposed in 1667 by Johann Joachim Becher. He offered the idea of the existence of a 5th fire-like element called phlogiston. He said that it was contained within combustible bodies and released during combustion. The theory was an attempt to explain the processes of combustion and rusting of metals. The theory was ultimately challenged by the discovery that some metals such as magnesium gained weight when burned when they should have lost weight due to the loss of phlogiston. In defense some scientists claimed that phlogiston had negative weight. Louis-Bernard Guyton de Morveau said that the element was lighter than air. In 1753 Mikhail Lomonsov concluded the theory was false.