from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A hypothetical substance formerly thought to be a volatile constituent of all combustible substances, released as flame in combustion.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The hypothetical fiery principle formerly assumed to be a necessary constituent of combustible bodies and to be given up by them in burning.

from the GNU version of the Collaborative International Dictionary of English

  • n. The hypothetical principle of fire, or inflammability, regarded by Stahl as a chemical element.

from The Century Dictionary and Cyclopedia

  • n. In old chemistry, the supposed principle of inflammability; the matter of fire in composition with other bodies.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a hypothetical substance once believed to be present in all combustible materials and to be released during burning


from The American Heritage® Dictionary of the English Language, 4th Edition

From Greek, neuter of phlogistos, inflammable, from phlogizein, to set on fire, from phlox, phlog-, flame; see bhel-1 in Indo-European roots.

from Wiktionary, Creative Commons Attribution/Share-Alike License

Coined by Stahl in 1702, from Ancient Greek φλογιστόν (phlogiston), neuter of φλογιστός (phlogistos, "inflammable"), from φλογίζω (phlogizō, "to set fire to"), from φλόξ (phloks, "flame").


  • We decline entering into a minute examination of his experiments, as few of his recitals of them are free from the triune mystery of phlogiston, which exceeds the utmost stretch of our faith; for according to it, carbon is phlogiston, and hydrogen is phlogiston, and azote is phlogiston; and yet there are not three phlogistons, but one phlogiston!

    Priestley in America 1794-1804

  • Yet it may not be altogether amiss to reflect that the physicist of to-day is no more certain of his ether than was his predecessor of the eighteenth century of the existence of certain alleged substances which he called phlogiston, caloric, corpuscles of light, and magnetic and electric fluids.

    A History of Science: in Five Volumes. Volume III: Modern development of the physical sciences

  • With precipitated indigo, the orpiment doesn't create changes, Bergman continued, because the union of phlogiston is too strong — you need the heat and the alkali to relax it.

    The Creation of Color in Eighteenth-Century Europe

  • Does this mean a science fiction story cannot be set in a fantasy universe where the theory of phlogiston is true?

    Author vs. Critic - A Fairy Tale

  • Stahl, the author of this theory, asserted that there is a principle of inflammability, to which he gave the name phlogiston, having the quality of uniting with substances.

    History of the Conflict between Religion and Science

  • The same germ-idea underlying these doctrines is to be found much later in Stahl's phlogistic theory (eighteenth century), which attempted to account for the combustibility of bodies by the assumption that such bodies all contain "phlogiston" -- the hypothetical principle of combustion (see § 72) -- though the concept of "phlogiston" approaches more nearly to the modern idea of an element than do the alchemistic elements or principles.

    Alchemy: Ancient and Modern

  • In Fooling with Words: A Celebration of Poets and Their Craft, the TV documentarian Bill Moyers, quoting this poem, asked the author about the meaning of the unfamiliar word phlogiston.

    No Uncertain Terms

  • This was a forerunner of the phlogiston theory (1723), which claimed, before the discovery of oxygen, that a nonexistent chemical called phlogiston was released during combustion.


  • A peculiarity of the strange thing called phlogiston was that it preferred to be concealed in something, hidden, imprisoned, combined; free phlogiston* was supposed to be always ready to become combined phlogiston.

    The Story of Alchemy and the Beginnings of Chemistry

  • It is the so-called phlogiston-theory first proposed by the chemist Stahl (1660-1734).

    Man or Matter


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  • The existence of phlogiston was denied by Lavoisier in 1775, and though stoutly maintained by Priestley, belief in it was generally abandoned by 1800.

    --Sir James Murray's New English Dictionary, 1909

    January 16, 2018

  • "Its major property was that it had negative mass."

    However, this old theory requires that phlogiston has weight when used to explain burning (since ashes weigh less most of the time), but when used to explain the corrosion it required that it had no weight or negative weight, since corroded metals weigh the same or more as they did before corrosion.

    A completely schizophrenic theory

    October 26, 2009

  • See also dephlogisticated.

    August 18, 2008

  • Its major property was that it had negative mass.

    July 20, 2008

  • I love this word. I have for years.

    July 20, 2008