Phlogiston theory was a 17th century attempt to explain oxidation processes, such as fire and rust.

The phlogiston theory (from the Ancient Greek phlogios: "fiery") is an obsolete scientific theory, stated initially in 1667 by Johann Joachim Becher, whereby in relation to the classical four elements of the Greeks, there was an additional fire-like substance called “phlogiston” that was contained within combustible bodies, and released, to lesser or greater degrees, during combustion. The theory was an attempt to explain oxidation processes, such as combustion and the rusting of metals. Large Bonfire File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Large Bonfire File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... (16th century - 17th century - 18th century - more centuries) As a means of recording the passage of time, the 17th century was that century which lasted from 1601-1700. ... Note: This article contains special characters. ... The obsolete Geocentric model of the universe places the Earth at the centre. ... J.J. Becher Johann Joachim Becher (May 6, 1635 – October 1682), was a German physician, alchemist, precursor of Chemistry, scholar and adventurer. ... Several ancient Classical Element ideas exist. ... A combustion reaction taking place in a igniting match Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ... Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... A combustion reaction taking place in a igniting match Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ... A blacksmith removing rust with sand prior to welding Rust damage in automobiles can create hidden dangers. ...

Theory

The theory holds that all flammable materials contain phlogiston, a substance without color, odor, taste, or weight that is liberated in burning. Once burned, the "dephlogisticated" substance was held to be in its "true" form, the calx. Flammable or Flammability refers to the ease at which a substance will ignite, causing fire or combustion. ... Color is an important part of the visual arts. ... Odor receptors on the antennae of a Luna moth An odor or odour (see spelling differences) is a chemical dissolved in air, generally at a very low concentration, which we perceive by the sense of olfaction. ... Taste is one of the traditional five senses and refers to the ability to detect the flavor of foodstuffs and other substances (e. ... A spring scale measures the weight of an object In the physical sciences, weight is a measurement of the gravitational force acting on an object. ... Calx is a residual substance, sometimes in the form of a fine powder, that is left when a metal or mineral combusts or is calcinated due to heat. ...

"Phlogisticated" substances are those that contain phlogiston and are "dephlogisticated" when burned. Since any substance could be observed to burn for only a limited time with air (for instance in a sealed container), air was thought to have a specific capacity for phlogiston.

Joseph Black's student Daniel Rutherford discovered nitrogen in 1772 and the pair used the theory to explain his results. The residue of air left after burning, in fact a mixture of nitrogen and carbon dioxide, was sometimes referred to as "phlogisticated air", having taken up all of the phlogiston. Joseph Black Joseph Black (April 16, 1728 - December 6, 1799) was a Scottish physicist and chemist. ... Daniel Rutherford, (November 3, 1749 – November 15, 1819), was a Scottish chemist and physician who was most famous for the discovery of nitrogen in 1772. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Year 1772 was a leap year starting on Wednesday (see link for calendar). ... Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ...

Conversely, when oxygen was first discovered it was thought to be "dephlogisticated air", capable of combining with more phlogiston and thus supporting combustion for longer than ordinary air. General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ...

Challenge and demise

Eventually, quantitative experiments revealed problems, including the fact that some metals, such as magnesium, gained weight when they burned, even though they were supposed to have lost phlogiston. Mikhail Lomonosov attempted to repeat Robert Boyle's celebrated experiment in 1753 and concluded that the phlogiston theory was false. He wrote in his diary: "Today I made an experiment in hermetic glass vessels in order to determine whether the mass of metals increases from the action of pure heat. The experiment demonstrated that the famous Robert Boyle was deluded, for without access of air from outside, the mass of the burnt metal remains the same." In the scientific method, an experiment (Latin: ex-+-periri, of (or from) trying), is a set of actions concerning phenomena. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... Mikhail Vasilyevich Lomonosov Mikhail Vasilyevich Lomonosov (Михаи́л Васи́льевич Ломоно́сов) (November 19 (November 8, Old Style), 1711 – April 15 (April 4, Old Style), 1765) was a Russian writer and polymath who made important contributions to literature, education, and science. ... Robert Boyle Robert Boyle (25 January 1627 – 30 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, inventor, and early gentleman scientist, noted for his work in physics and chemistry. ...

Some phlogiston proponents explained this by concluding that phlogiston had "negative weight"; others, such as Louis-Bernard Guyton de Morveau, gave the more conventional argument that it was lighter than air. However, a more detailed analysis based on the Archimedean principle and the densities of magnesium and its combustion product shows that just being lighter than air cannot account for the increase in mass. Louis-Bernard Guyton de Morveau. ... In mathematics (particularly abstract algebra), the Archimedean property is a property held by some ordered algebraic structures, and in particular by the ordered field of real numbers. ...

Still, phlogiston remained the dominant theory until Antoine-Laurent Lavoisier showed that combustion requires oxygen, solving the weight paradox and setting the stage for the new caloric theory of combustion. Antoine-Laurent de Lavoisier (August 26, 1743 – May 8, 1794) was a French nobleman prominent in the histories of chemistry, finance, biology, and economics. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... The caloric theory is an obsolete scientific theory that heat consists of a fluid called caloric that flows from hotter to colder bodies. ...

In some respects, the phlogiston theory can be seen as the opposite of the modern "oxygen theory". The phlogiston theory states that all flammable materials contain phlogiston that is liberated in burning, leaving the "dephlogisticated" substance in its "true" calx form. In the modern theory, on the other hand, flammable materials (or unrusted metals) are "deoxygenated" when in their pure form and become oxygenated when burned.

Enduring aspects

Phlogiston theory allowed chemists to bring explanation of apparently different phenomena into a coherent structure: combustion, metabolism, and formation of rust. The recognition of the relation between combustion and metabolism was a forerunner of the recognition that the metabolism of living creatures and combustion can be understood in terms of fundamentally related chemical processes. A few of the metabolic pathways in a cell. ...

References