List of discredited substances

This page is a list of substances or materials generally considered discredited.

A substance can be discredited in one of three ways:

1. It was widely believed to exist at one time but no longer is. Such substances are often part of an obsolete scientific theory.
2. It was once believed to have drastically different properties from those accepted now. It was widely claimed and believed to possess significant properties that are no longer attributed to it.
3. It is currently believed to exist as part of a theory that has not met the theoretical and experimental requirements of mainstream science. In particular, such a theory must be predictive.

Alphabetical list of substances whose existence is discredited

Substance	Theorized by	From when	Alleged definition	Discredited by
Aether (classical element)		ancient	A substance with rapid, circular motion that makes up celestial bodies	atomic theory
Alicorn		ancient	The horn of the unicorn, has mystical healing properties	failure to find any since medieval times
Alkahest	Paracelsus	1493–1541	A universal solvent, which can dissolve every other substance, including gold	(Note that aqua regia can dissolve gold, but not everything.)
Caloric	Antoine Lavoisier	1783	Weightless fluid, the substance of heat	atomic theory, in which heat is interpreted as energy of motion of atoms.
Coronium	Charles Augustus Young and William Harkness	1869	Chemical element in the solar corona	In the 1930s, Walter Grotrian and Bengt Edlén discovered that the spectral line in question was due to highly ionized iron.
Élan vital	Henri Bergson	1907	Substance or force bearing the property of life	molecular biology
Elixir of life	mythology	ancient	Substance believed by alchemists to confer immortality	chemistry and biology
Erototoxins	Judith Reisman	after 1955	Addictive chemicals produced in the brain by pornography	(There are addictive opioids (i.e. endorphins) in the brain related to pleasure in general, but not specific to pornography.)
Luminiferous aether		18th century	Medium for the propagation of light	Michelson-Morley experiment
Miasma		ancient	Foul smell believed to carry diseases	modern biology, in particular the discovery of actual infectious agents
Nebulium	William Huggins	1864	An element in the Cat's Eye Nebula	In 1927, Ira Sprague Bowen showed that the observed spectral lines are emitted by doubly ionized oxygen.
N-rays	Prosper-René Blondlot	1903	A form of radiation emitted by most substances	a simple null experiment, where Blondlot thought he could see N-rays even when an essential optical element had been removed from the experiment
Odic force	Carl Reichenbach	1845	Force bearing the property of life	Lack of experimental evidence and any predictive theory. Never accepted by science.
Orgone energy	Wilhelm Reich	1930s	Energy bearing the property of life	Lack of experimental evidence and any predictive theory. Never accepted by science.
Panacea	alchemists	ancient	Substance curing all illness	biology and medicine
Philosopher's stone	alchemists	ancient	Substance transmuting other metals into gold	atomic theory
Phlogiston	Johann Joachim Becher	1667	Weightless substance present in combustible materials and released when they are burned	modern chemistry, specifically the discovery that combustion is combination of various substances with oxidizers, most commonly oxygen.
Polywater		late 1960s	An apparently polymerised form of water	more careful experiments with rigorously cleaned glassware
Ptomaines			alkaloids found in decaying matter thought to cause food poisoning	discovery of bacteria
Red mercury	hoax	1979	Controversial substance supposedly of use to terrorists	Its actual nature, if any, is unclear. The notion may have been invented for use by Soviet and Russian sting operations targeting nuclear materials trafficking. It is also possible that the phrase may have originated as a codeword in Soviet nuclear weapons development, much as the word "copper" was once used to obfuscate "plutonium" during the Manhattan Project.
Terra Pinguis (combustible earth)	J. J. Becher	1635–1682	The forerunner of phlogiston	It would have had negative weight; Lavoisier's invention of the beginnings of modern quantitative chemistry. Terra Pinguis is equivalent to the absence of oxygen.

Alphabetical list of substances whose properties are discredited

This is not to be construed as implying that these items–as they are understood today–are discredited. What is listed are fire, water, metal, etc. as universal principles or fundamentals.

• Classical elements and Chinese elements Discredited by atomic theory and nuclear physics.
  • Fire (classical element)
  • Water (classical element)
  • Earth (classical element)
  • Air (classical element)
  • Wood (classical element)
  • Metal (classical element)
  • Aether (classical element): Now known not to exist (see above)
• The four bodily humours: Blood, Phlegm, Black Bile, & Yellow Bile. Fluids believed to determine health and character. Discredited by modern biology, including discovery of hormones.
• The tria prima of Paracelsus and later alchemy: Salt, Mercury and Sulphur. Discredited by modern chemistry (the atomic theory and modern understanding of elements and compounds).

See also

• List of fictional toxins
• List of fictional elements, materials, isotopes and atomic particles