What is phlogiston?
The theory created by Georg Ernst Stahl was one of the valid explanations for the phenomenon of combustion until the late seventeenth century, when Lavoisier proved it was wrong.
The phlogiston is the scientific theory, already refuted, that sought to give an explanation to the combustion process through the existence of a substance that have the bodies susceptible to undergo a combustion called phlogiston, whose presence would be what would cause the object to burn. It is considered as the first great theory of modern chemistry and was postulated by the physician and alchemist (chemist) Georg Ernst Stahl at the beginning of the 18th century, based on the previous works of his teacher, J. J. Becher.
Stahl (1660-1734), assumed that heat can occur in two different ways: free and in combination. This second form is what he referred to as phlogiston, which means 'flammable' in Greek. For Stahl, this substance is inherent in all combustible bodies and, therefore, combustion would be the passage of this form of combined fire to the free form, where it could be appreciated with the senses. The phlogiston would be a substance that contains all the combustible objects that is the one that really burns and that, when finished, would only leave the ashes and the remainders that remain after the combustion. These remains are unable to burn again because they would have spent all the phlogiston of the body. For example, Stahl believed that the metal was composed of phlogiston and lime and when combustion was produced, only the lime remained; but if a substance that was rich in phlogiston (such as coal) was added, it could be returned to the original state.
This interpretation about combustion was refuted at the end of the 18th century, when the chemist and biologist Antoine-Laurent Lavoisier, known for his studies on the oxidation of bodies or the law of conservation of mass, showed that combustion was the result of a relatively fast chemical reaction and exothermic character. The studies of Lavoisier relieved the theory of phlogiston to an obsolete place within the world of science.
