A factitious article is prepared by calcining a mixture of colcothar and red ochre.
When this colcothar hath undergone a violent fire, as in the experiment now related, scarce any Acid remains therein.
colcothar of Vitriol, and Crocus of Mars, are old names for red oxide of iron.
The wooden disc is also employed for this purpose with putty, colcothar, or washed tripoli.
When the cork or wooden disc edged with hat felt is used for polishing, putty or colcothar is applied to it.
Emery with oil is used for grinding down, and tin-putty or colcothar for polishing.