Alchemical symbols, originally devised as part of alchemy, were used to denote some elements and some compounds until the 18th century. Note that while notation like this was mostly standardized, style and symbol varied between alchemists, so this page lists the most common.
Three primes 
- Salt (base matter)
- Mercury (fluid connection between the High and the Low)
- Sulfur (omnipresent spirit of life)
Four basic elements 
Western alchemy makes use of the Hellenic elements. The symbols used for these are:
Seven planetary metals 
Seven metals are associated with the seven classical planets, and seven deities, all figuring heavily in alchemical symbolism. Although the metals occasionally have a glyph of their own, the planet's symbol is used most often, and the symbolic and mythological septenary is consistent with Western astrology. The planetary symbolism is limited to the seven wandering stars visible to the naked eye, and the extra-Saturnarian planets such as Neptune are not used.
- Gold dominated by Sol ☉ ☼ ( )
- Silver dominated by Luna ☽ ( )
- Copper dominated by Venus ♀ (also: )
- Iron dominated by Mars ♂ ( )
- Tin dominated by Jupiter ♃ ( )
- Mercury (quicksilver) dominated by Mercury ☿ ( )
- Lead dominated by Saturn ♄ ( )
Mundane elements 
Alchemical compounds 
- Sal ammoniac *
- Aqua Fortis A.F.
- Aqua Regia A.R.
- Spirit of Wine S.V.
- Cinnabar (Mercury sulfide)
Alchemical processes 
The alchemical magnum opus was sometimes expressed as a series of chemical operations. In cases where these numbered twelve, each could be assigned one of the Zodiac signs as a form of cryptography. The following example can be found in Pernety's 1758 Mytho-Hermetic Dictionary:
- Calcination (Aries )
- Congelation (Taurus )
- Fixation (Gemini )
- Dissolution (Cancer )
- Digestion (Leo )
- Distillation (Virgo )
- Sublimation (Libra )
- Separation (Scorpio )
- Incineration (Sagittarius )
- Fermentation (Capricorn)
- Multiplication (Aquarius )
- Projection (Pisces )
Unicode 6.1 adds support for an Alchemical Symbols plane.
Unicode.org chart (PDF)
- Eric John Holmyard. Alchemy. 1995. p.153
- Walter J. Friedlander. The golden wand of medicine: a history of the caduceus symbol in medicine. 1992. p.76-77
- Antoine-Joseph Pernety. Dictionnaire mytho-hermétique, dans lequel on trouve les allégories fabuleuses des poètes, les métaphores, les énigmes et les termes barbares des philosophes hermétiques expliqués. 1758. p.99
- Alchemical symbols in Unicode 6.0