Calx is a substance formed from an ore or mineral that has been heated. Calx, especially of a metal, is now known as an

oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...

. According to the obsolete

phlogiston theory The phlogiston theory is a superseded scientific theory that postulated the existence of a fire-like element called phlogiston () contained within combustible bodies and released during combustion. The name comes from the Ancient Greek (''bur ...

, the calx was the true elemental substance, having lost its phlogiston in the process of

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...

. "Calx" is also sometimes used in older texts on artist's techniques to mean

calcium oxide Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "'' lime''" connotes calcium-containing inorganic ...

Etymology

Calx is Latin for

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. C ...

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

, from the Greek χάλιξ (''khaliks'', “pebble”). It is not to be confused with the Latin

homonym In linguistics, homonyms are words which are homographs (words that share the same spelling, regardless of pronunciation), or homophones ( equivocal words, that share the same pronunciation, regardless of spelling), or both. Using this definitio ...

meaning

heel The heel is the prominence at the posterior end of the foot. It is based on the projection of one bone, the calcaneus or heel bone, behind the articulation of the bones of the lower leg. Structure To distribute the compressive forces exer ...

bone (or

calcaneus In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel) or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is the point of the hock. ...

in modern medical Latin), which has an entirely separate derivation.

In popular culture

* UK

electronic music Electronic music is a genre of music that employs electronic musical instruments, digital instruments, or circuitry-based music technology in its creation. It includes both music made using electronic and electromechanical means ( electro ...

artist

Aphex Twin Richard David James (born 18 August 1971), best known as Aphex Twin, is an Irish-born British musician, composer and DJ. He is known for his idiosyncratic work in electronic styles such as techno, ambient, and jungle. Journalists from publicati ...

named four of his tracks after differently coloured calxes (green, yellow, blue and red).

References

Inorganic chemistry {{Chem-stub