The phlogiston theory (from the Ancient Greek φλογιστόν phlogistón “burning up”, from φλόξ phlóx “flame”), first stated in 1667 by Johann Joachim Becher, is an obsolete scientific theory that postulated the existence of a fire-like element called “phlogiston”, which was contained within combustible bodies and released during combustion. The theory was an attempt to explain processes of burning such as combustion and the rusting of metals, which are now collectively known as oxidation.