colcothar

[ kol-kuh-ther ]

/ ˈkɒl kə θər /

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.

Nearby words

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

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 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
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

A factitious article is prepared by calcining a mixture of colcothar and red ochre.
Cooley's Practical Receipts, Volume II|Arnold Cooley

British Dictionary definitions for colcothar

colcothar

/ (ˈkɒlkəˌθɑː) /

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