Reactions of the Brown Pigments.

Pigment.Hydrochloric
Acid.		Caustic
Soda.		Ammonium
Sulphide.		On Heating.
Lead brownWhite residue,
chlorine evolved.		Dissolves.Blackened.Turns yellow and fuses.
Manganese brown Dissolves to
yellow solution.		UnalteredBecomes flesh
coloured.		Unaltered
Pyrolusite brownDissolves to
yellow solution,
chlorine evolved. 		Unaltered.Becomes flesh
coloured.		Unaltered.
Prussian brownDissolves to
yellow solution.		Unaltered.Blackened.Turns to reddish brown.
Iron brownDissolves to
yellow solution.		Unaltered.Blackened.Unaltered.
Chrome brownDissolves to
greenish yellow
solution.		Yellow solution,
black residue.		Blackened.Blackened.
Cobalt brownDissolves to
reddish yellow
solution.		Unaltered or
blackened.		Blackened.Unaltered.
Hatchett brownUnaltered.Becomes greenish
blue.		Blackened.Blackened.
Humins, BistreUnaltered,
yellow liquid.		Give yellow liquid. Unaltered.Burn.

On Heating on Charcoal:—Lead brown gives a lead bead in the reducing flame.

Manganese brown and pyrolusite brown, when fused with saltpetre on platinum foil at a high temperature, give a bluish-green mass.

Prussian brown and iron brown give a pale green borax bead in the reducing flame, which turns yellowish brown in the oxidising flame.

Chrome brown heated, moistened with hydrochloric acid, and again heated, colours the flame green. It also gives a green borax bead.

Cobalt brown produces a blue borax bead.

Humin substances burn when heated on charcoal.