Caput mortuum

Caput mortuum (plural capita mortua; literally "dead head") is a Latin term used in alchemy to signify a useless substance left over from a chemical operation such as sublimation and the epitome of decline and decay (alternatively called nigredo). Alchemists represented this residue with a stylized human skull, a literal death's head.^[1]

The symbol shown on this page was also used in 18th-century chemistry to mean residue, remainder, or residuum. Caput mortuum was also sometimes used to mean crocus metallorum, i.e. brownish-red metallic compounds such as crocus martis (ferrous sulfate), and crocus veneris (copper oxidule).^[2]

References

^ Eastaugh, Nicholas (2004). Pigment Compendium: A Dictionary of Historical Pigments. Butterworth-Heinemann. p. 81. ISBN 0-7506-5749-9.
^ Liungman, Carl G. (2004). Symbols: Encyclopedia of Western Signs and Ideograms. Ionfox AB. p. 236. ISBN 91-972705-0-4. Retrieved January 20, 2023 – via Google Books.

[eastaugh-1] Eastaugh, Nicholas (2004). Pigment Compendium: A Dictionary of Historical Pigments. Butterworth-Heinemann. p. 81. ISBN 0-7506-5749-9.

[2] Liungman, Carl G. (2004). Symbols: Encyclopedia of Western Signs and Ideograms. Ionfox AB. p. 236. ISBN 91-972705-0-4. Retrieved January 20, 2023 – via Google Books.

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