Unimportant Blacks.—In addition to the recognised blacks already noticed there are a number of other sources of black pigment which have been drawn upon to a limited extent, or have been suggested as substitutes for the standard articles. They only merit a short description.
Aniline black is prepared by adding an acidified (sulphuric) solution of bichromate of potash to an aqueous solution of hydrochlorate of aniline, and washing the precipitate. The cost is prohibitive.
Candle black is candle smoke condensed on a cold plate.
Charcoal black is finely-ground wood charcoal.
Coal black has been suggested by grinding coal, but lacks the requisite qualities of a pigment.
Cork black is a very fine pigment prepared by calcining cork refuse. Limited supply.
German black is Frankfort black.
Iron black is ground black sulphide of iron.
Lead black is prepared by boiling lead fume in sulphide of soda solution. It would probably be unstable on account of oxidation.
Manganese black is ground oxide of manganese. It is costly, and dries too quickly.