Philogiston Theory
Phlogiston Theory
According to the phlogiston theory, propounded in the 17th century, every combustible substance consisted of a hypothetical principle of fire known as phlogiston, which was liberated through burning, and a residue. The word phlogiston was first used early in the 18th century by the German chemist Georg Ernst Stahl. Stahl declared that the rusting of iron was also a form of burning in which phlogiston was freed and the metal reduced to an ash or calx. The theory was superseded between 1770 and 1790 when the French chemist Antoine Lavoisier showed that burning and rusting both involved oxygen and concluded that both ash and rust were compounds of oxygen. Lavoisier's oxidization theory has been accepted by scientists from about 1800 to the present day.
The theory of phlogiston was predominantly German in origin, with much early work done in Mainz, though it was widely believed through much of the eighteenth century -- two of the most prominent followers of the theory, Johann Joachim Becher and Georg Ernst Stahl (who first used the name phlogiston in 1700), were
Swedish. Phlogiston was not only widespread but deep-seated, and gave way to the atomic theory only slowly.
Phlogiston theorists identified three essences which comprise all matter: sulfur or terra pinguis, the essence of inflammability; mercury or terra mercurialis, the essence of fluidity; and salt or terra lapida, the essence of fixity and inertness. In this respect phlogiston theory is similar to the ancient alchemical notions of earth, air, fire, and water. The terra pinguis was renamed phlogiston. In this view, metals were made of a "calx" (or residue) combined with phlogiston, the fiery principle, which was liberated during combustion, leaving only the calx. Air, according to the theory, was merely the receptacle for phlogiston; all combustible or calcinable substances, in fact, were not elements but compounds containing phlogiston. Rusting iron, for instance, was
According to the phlogiston theory, propounded in the 17th century, every combustible substance consisted of a hypothetical principle of fire known as phlogiston, which was liberated through burning, and a residue. The word phlogiston was first used early in the 18th century by the German chemist Georg Ernst Stahl. Stahl declared that the rusting of iron was also a form of burning in which phlogiston was freed and the metal reduced to an ash or calx. The theory was superseded between 1770 and 1790 when the French chemist Antoine Lavoisier showed that burning and rusting both involved oxygen and concluded that both ash and rust were compounds of oxygen. Lavoisier's oxidization theory has been accepted by scientists from about 1800 to the present day.
The theory of phlogiston was predominantly German in origin, with much early work done in Mainz, though it was widely believed through much of the eighteenth century -- two of the most prominent followers of the theory, Johann Joachim Becher and Georg Ernst Stahl (who first used the name phlogiston in 1700), were
Swedish. Phlogiston was not only widespread but deep-seated, and gave way to the atomic theory only slowly.
Phlogiston theorists identified three essences which comprise all matter: sulfur or terra pinguis, the essence of inflammability; mercury or terra mercurialis, the essence of fluidity; and salt or terra lapida, the essence of fixity and inertness. In this respect phlogiston theory is similar to the ancient alchemical notions of earth, air, fire, and water. The terra pinguis was renamed phlogiston. In this view, metals were made of a "calx" (or residue) combined with phlogiston, the fiery principle, which was liberated during combustion, leaving only the calx. Air, according to the theory, was merely the receptacle for phlogiston; all combustible or calcinable substances, in fact, were not elements but compounds containing phlogiston. Rusting iron, for instance, was