colcothar

American  

[kol-kuh-ther] / ˈkɒl kə θər /

noun

Chemistry.

1. the brownish-red oxide of iron produced by heating ferrous sulfate: used chiefly as a pigment in paints and theatrical rouge, and as a polishing agent.

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colcothar British  

/ ˈkɒlkəˌθɑː /

noun

1. Also called: crocus.  a finely powdered form of ferric oxide produced by heating ferric sulphate and used as a pigment and as jewellers' rouge

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Etymology

Origin of colcothar

1595–1605; < Medieval Latin < Old Spanish colcotar, Spanish Arabic qulquṭār, perhaps < Greek chálkanthos copper sulfate solution

Example Sentences

The precipitates of gold, and the colcothar or other red preparations of iron, are called tender colours.

From The Botanic Garden A Poem in Two Parts. Part 1: the Economy of Vegetation by Darwin, Erasmus

The solution of iron in spirit of vitriol produces green copperas; which being calcined, becomes a red substance, called colcothar.

From Heads of Lectures on a Course of Experimental Philosophy: Particularly Including Chemistry by Priestley, Joseph

The colors used for this style of painting are zinc white, green oxide of chrome, cobalt green, chromate of lead, colcothar, ochers, and ultramarine.

From Scientific American Supplement, No. 483, April 4, 1885 by Various

Ferric oxide is known as colcothar, English-Roth, rouge, crocus, etc.

From Friction, Lubrication and the Lubricants in Horology by Lewis, William T.