What does phlogiston mean?
Phlogiston was a hypothetical substance that chemists once believed was contained within combustible materials and released as they burned. Under this theory, wood and other fuels burned because phlogiston escaped from them, while substances such as charcoal were thought to be nearly pure phlogiston. The concept was developed by Georg Stahl and others as an influential chemical theory during the early eighteenth century. It was undermined by the work of Antoine Lavoisier and others, whose experiments showed that combustion instead involves a chemical reaction with oxygen. Although phlogiston is no longer part of scientific chemistry, the word remains well known as a reminder of how observation and experiment can overturn an accepted explanatory framework. It is also used metaphorically in cultural and historical discussions as a symbol of an obsolete doctrine.
nounPhlogiston was a hypothetical substance that eighteenth- and nineteenth-century chemists believed was released during combustion. The theory was eventually disproved when oxygen and the role of chemical reactions in burning were properly understood.
- The hypothetical substance believed by eighteenth- and nineteenth-century chemists to be released during combustion.
- By extension, the associated historical theory of combustion, especially in phrases such as “the phlogiston theory.”
"Lavoisier’s experiments challenged the long-accepted doctrine of phlogiston and helped establish modern chemistry."
"The discovery of oxygen appeared to provide an explanation for combustion that did not require phlogiston."
"Today, references to phlogiston usually occur in histories of chemistry or discussions of obsolete scientific theories."
Rarely used; phlogiston is normally uncountable.
"Historians of chemistry once described phlogistons as hypothetical substances associated with the old theory of combustion."
For much of modern history, chemists explained fire by imagining an invisible substance escaping from burning matter—an idea that eventually became one of science’s most famous mistakes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does phlogiston come from?
The word comes from Greek phlogiston, meaning “burning thing” or “inflammable principle.” It was adopted into eighteenth-century chemical terminology through the Latin form phlogiston, from the Greek phlogizein, “to set on fire,” and was associated with phlogos, meaning “flame.” The resulting theory was influential for roughly a century before the development of modern oxygen-based accounts of combustion.
Related word forms
How phlogiston is actually used
The word is historical and is not used in modern scientific discussion except when referring to the former theory of combustion. It is usually treated as an uncountable noun, although a plural form occasionally appears in historical writing.
Easily confused with phlogiston
Phlogiston was the hypothetical substance itself, whereas phlogistic describes something involving or believed to involve phlogiston.