Phlogiston theory held that combustible materials contain a fire-like substance called phlogiston, released into the air when the material burns. Johann Joachim Becher introduced the underlying idea in 1667, and Georg Ernst Stahl named and popularized it around 1703. It explained why burning felt like a release, but it could not explain why metals gain weight when they burn, since a substance being released should leave the remainder lighter, not heavier. Antoine Lavoisier's sealed vessel experiments in the 1770s and 1780s showed that combustion instead consumes a gas, oxygen, from the air, and phlogiston theory was abandoned once his account could explain the weight gain that phlogiston theory could not. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/
Facts
Proposed YearSourced to the subject's own accountDated to Georg Ernst Stahl's naming and popularizing of the theory around 1703; Johann Joachim Becher had introduced the underlying idea, under the name terra pinguis, in 1667. Proposed BySourced to the subject's own accountJohann Joachim Becher and Georg Ernst Stahl 1 FAQs
Did supporters of phlogiston theory have an answer for metals gaining weight when they burn?
Yes: some supporters proposed that phlogiston had negative weight or drove heavy air out of the metal, until careful weighing in the late 1770s ruled both ideas out.
Yes, at first they did. Some phlogiston theorists argued that phlogiston had a kind of levitation property, even a negative weight, so losing it could make a product heavier. Another explanation held that the nearly weightless phlogiston drove heavy, condensed air out of the pores of the burned metal, leaving a lighter product. Chemists at the time found these explanations reasonable, partly because the idea of mass did not yet play a central role in chemistry. By the end of the 1770s Torbern Bergman had carefully weighed metals and their calxes and showed that the weight gained equalled the weight of oxygen lost by the surrounding air, which ruled out both explanations. Even so, he kept phlogiston and argued that it combined with the oxygen in the air. Lavoisier simplified the account by removing phlogiston from it altogether, a moment many call the Chemical Revolution.
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Belongs To
Precursor To
Phlogiston theory correctly identified combustion as a real chemical transformation and organized a century of experimental chemistry, but could not explain why metals gain weight when they burn. Joseph Priestley's own 1774 isolation of oxygen, read by him within phlogiston theory as dephlogisticated air, supplied the experimental fact that Antoine Lavoisier reinterpreted through careful mass measurements as combination with a gas drawn from the air; Lavoisier's 1783 Reflections on Phlogiston presented oxygen theory as phlogiston theory's replacement, explaining the weight gain the older theory could not.
Source Phlogiston Theory (Wikipedia)
Proposed By
Stahl named phlogiston and systematized the theory around 1703, developing Becher's earlier terra pinguis concept into the doctrine that dominated eighteenth-century chemistry.
Source Phlogiston Theory (Wikipedia)
Becher's 1667 Physica Subterranea proposed the terra pinguis, fatty earth, concept that Stahl renamed phlogiston and developed into the full theory around 1703.
Source Phlogiston Theory (Wikipedia)
Sources
1. Phlogiston Theory (Wikipedia)
Dissenting Readings (1 dissenting reading)
Precursor To: Oxygen Theory of Combustion
Priestley isolated the gas this transition turns on, on 1 August 1774, but he never accepted Antoine Lavoisier's reinterpretation of it. Working from phlogiston theory himself, he called the gas dephlogisticated air and defended phlogiston theory for the rest of his life after visiting Lavoisier in Paris that October and watching him repeat and reinterpret the same experiment. Carried here as the documented historical position of the very chemist whose own data the rival theory was built from, not as a claim that his reading was correct.
A dissenting reading, from Joseph PriestleyJoseph Priestley (Britannica), Encyclopaedia Britannica
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