Definition of "colcothar" []

• A brownish-red ferric oxide obtained as a residue after heating ferrous sulfate, used in glass polishing and as a pigment. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Il est plus beau, plus vif que le brun-rouge d'Angleterre: Selon les uns, c'est une terre calcinée; selon d'autres, dont je crois l'opinion fondée, c'est le colcothar ou caput mortuum des eaux fortes qu'on réduit en poudre fine, après avoir bien lavées."
• "The colors used for this style of painting are zinc white, green oxide of chrome, cobalt green, chromate of lead, colcothar, ochers, and ultramarine."
• "The precipitates of gold, and the colcothar or other red preparations of iron, are called _tender_ colours."