Manganese green is discoloured in the reducing flame.
Reactions of the Brown Pigments.
| Pigment. | Hydrochloric Acid. | Caustic Soda. | Ammonium Sulphide. | On Heating. |
|---|---|---|---|---|
| Lead brown | White residue, chlorine evolved. | Dissolves. | Blackened. | Turns yellow and fuses. |
| Manganese brown | Dissolves to yellow solution. | Unaltered | Becomes flesh coloured. | Unaltered |
| Pyrolusite brown | Dissolves to yellow solution, chlorine evolved. | Unaltered. | Becomes flesh coloured. | Unaltered. |
| Prussian brown | Dissolves to yellow solution. | Unaltered. | Blackened. | Turns to reddish brown. |
| Iron brown | Dissolves to yellow solution. | Unaltered. | Blackened. | Unaltered. |
| Chrome brown | Dissolves to greenish yellow solution. | Yellow solution, black residue. | Blackened. | Blackened. |
| Cobalt brown | Dissolves to reddish yellow solution. | Unaltered or blackened. | Blackened. | Unaltered. |
| Hatchett brown | Unaltered. | Becomes greenish blue. | Blackened. | Blackened. |
| Humins, Bistre | Unaltered, 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.