# List of discredited substances

This is a list of substances or materials generally considered discredited.
A substance can be discredited in one of three ways:
* It was widely believed to exist at one time but no longer is. Such substances are often part of an obsolete scientific theory.
* 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.
* 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.

## Substances whose existence is discredited

| Substance | Theorized by | From when | Alleged definition | Discredited by |
| Aether (classical element) | | Ancient times | The medium filling the universe above the terrestrial sphere enabling transmission of light and gravity | The Michelson–Morley experiment |
| Alicorn | | Ancient times | The horn of the unicorn, has mystical healing properties | Never found |
| Alkahest | Paracelsus | 1493–1541 | A universal solvent, which can dissolve every other substance, including gold | Never found (note that aqua regia can dissolve gold, but not everything) |
| Andrewsite | Thomas Andrews | 1871–1990 | Green mineral named for Thomas Andrews | Confirmation in 1990 that the substance is composed of other minerals |
| Caloric | Antoine Lavoisier | 1783 | Weightless fluid, the substance of heat | Heat came to be interpreted as the energy of the 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 times | Substance believed by alchemists to confer immortality | Never found |
| Erototoxins | Judith Reisman | after 1955 | Addictive chemicals produced in the brain by pornography | Addictive opioids (i.e. endorphins) in the brain are related to pleasure in general, not specific to pornography |
| Luminiferous aether | | 18th century | Medium for the propagation of light | Michelson–Morley experiment |
| Miasma | | Ancient times | 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 the effects of N-rays even when an essential component had been removed from the experimental apparatus |
| 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 times | Substance curing all illness | Modern biology and medicine |
| Philosopher's stone | Alchemists | Ancient times | Legendary substance that could transmute lead into precious metals | Transmutation requires nuclear processes. The first synthesis of gold was conducted by Japanese physicist Hantaro Nagaoka in 1924, who synthesized gold by bombarding mercury with neutrons. |
| 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 the combination of various substances with oxidizers, most commonly oxygen |
| Polywater | | late 1960s | A polymerised form of water | More careful experiments with rigorously cleaned glassware showed that it was just contaminated water |
| Ptomaines | | | Alkaloids found in decaying matter thought to cause food poisoning | Discovery of bacteria (Germ theory of disease) |
| 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. |

## 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, and 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).