Calx

Calx is a substance formed from an ore or mineral that has been heated.^[1] Calx, especially of a metal, is now understood to be an oxide. The term is also sometimes used in older texts on artists' techniques to mean calcium oxide. ^{[citation needed]}

According to the obsolete phlogiston theory, the calx was the true elemental substance that was left after phlogiston was driven out of it in the process of combustion.^[2]

Etymology

Calx is Latin for chalk or limestone, from the Greek χάλιξ (khaliks, “pebble”). (It is not to be confused with the Latin homonym meaning heelbone (or calcaneus in modern medical Latin), which has an entirely separate derivation.)

In popular culture

• UK electronic music artist Aphex Twin named four of his tracks after differently coloured calxes (green, yellow, blue and red).

References

1. "calx | Definition of calx in English by Oxford Dictionaries". Oxford Dictionaries | English. Archived from the original on December 28, 2017. Retrieved 2017-12-28.
2. Daintith, John, ed. (2008). "Phlogiston theory". A Dictionary of Chemistry (6th ed.). Oxford University Press. doi:10.1093/acref/9780199204632.001.0001. ISBN 9780191726569 – via Oxford Reference. In the early 18th century Georg Stahl renamed the substance phlogiston (from the Greek for 'burned') and extended the theory to include the calcination (and corrosion) of metals. Thus, metals were thought to be composed of calx (a powdery residue) and phlogiston; when a metal was heated, phlogiston was set free and the calx remained. The process could be reversed by heating the metal over charcoal (a substance believed to be rich in phlogiston, because combustion almost totally consumed it). The calx would absorb the phlogiston released by the burning charcoal and become metallic again.