Phlogiston theory

Phlogiston theory held that combustible materials and metals contain a fire-like substance, phlogiston, released during burning and calcination. It was displaced by oxygen-based explanations of combustion.

Combustion: A chemical reaction in which a substance reacts rapidly with an oxidant, usually releasing heat and light. Phlogiston theory tried to explain combustion as the escape of a substance from burning materials.
Johann Joachim Becher: A German physician and chemist who proposed an early theory of material principles in the seventeenth century. Becher’s combustible-earth principle helped prepare the ground for phlogiston theory.
Joseph Priestley: An English chemist and natural philosopher who isolated several gases, including the gas later named oxygen. Priestley interpreted oxygen as dephlogisticated air and remained committed to phlogiston theory.
Chemical revolution: The late-eighteenth-century transformation of chemistry associated with oxygen theory, quantitative methods, and new nomenclature. The rejection of phlogiston became a defining episode in this transformation.
Caloric theory: An obsolete theory that treated heat as a weightless fluid called caloric. Like phlogiston, caloric explained physical change through an invisible material substance.
Calcination: The process of heating a substance, especially a metal, in air to produce a powder or oxide. The gain in mass during calcination became a central difficulty for phlogiston explanations.
Georg Ernst Stahl: A German physician and chemist who developed and popularized phlogiston theory in the early eighteenth century. Stahl recast Becher’s ideas into a systematic explanation of combustion and calcination.
Antoine Lavoisier: A French chemist who established oxygen’s role in combustion and helped transform chemistry into a quantitative science. Lavoisier’s experiments and terminology provided the strongest alternative to phlogiston.
Oxygen theory of combustion: The explanation that combustion involves a substance combining with oxygen, typically with heat and light released. It replaced phlogiston release with oxygen combination as the basis of combustion.
Oxygen: A chemical element that makes up about 21 percent of Earth’s atmosphere and supports many oxidation reactions. Oxygen provides the material reactant that phlogiston theory could not identify.

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