The phlogiston theory (from the Ancient Greek φλογιστόν phlŏgistón "burning up," from φλόξ phlóx "fire"), first state in 1667 by Johann Joachim Becher, is an obsolete scientific theory that posited the existence of, in addition to the classical four elements of the Greeks, an additional fire-like element called “phlogiston” that was contained within combustible bodies, and released during combustion. The theory was an attempt to explain oxidation processes such as combustion and the rusting of metals.