colcothar

[kol-kuh-ther]

noun Chemistry.

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.

Origin of colcothar

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

Also called jewelers' rouge.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for colcothar

Historical Examples of colcothar

A factitious article is prepared by calcining a mixture of colcothar and red ochre.
Cooley's Practical Receipts, Volume II
Arnold Cooley
When this Colcothar hath undergone a violent fire, as in the experiment now related, scarce any Acid remains therein.
Elements of the Theory and Practice of Chymistry, 5th ed.
Pierre Joseph Macquer
The wooden disc is also employed for this purpose with putty, colcothar, or washed tripoli.
A Dictionary of Arts, Manufactures and Mines
Andrew Ure
When the cork or wooden disc edged with hat felt is used for polishing, putty or colcothar is applied to it.
A Dictionary of Arts, Manufactures and Mines
Andrew Ure
Emery with oil is used for grinding down, and tin-putty or colcothar for polishing.
A Dictionary of Arts, Manufactures and Mines
Andrew Ure

British Dictionary definitions for colcothar

colcothar

noun

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

Word Origin for colcothar

C17: from French colcotar, from Spanish colcótar, from Arabic dialect qulqutār

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012