Ultramarine is unaltered at a high temperature. Smalts, on long heating in the reducing flame with borax, gives a dark blue bead. Cobalt blue is infusible; it colours the borax bead blue. The bead loses its fine colour on long heating in the reducing flame. Mountain blue is blackened before the blowpipe. When the residue is moistened with hydrochloric acid and again heated, the flame is coloured bright green. When fused with borax in the oxidising flame, an emerald green bead is formed. REACTIONS OF THE GREEN PIGMENTS. +---------------+---------------+----------+------------+-----------+ | Pigment. | Hydrochloric | Caustic | Ammonium |On Heating.| | | Acid. | Soda. | Sulphide. | | +---------------+---------------+----------+------------+-----------+ |Verdigris |Dissolves |Unaltered.|Blackened. |Blackened | |(all varieties)|to green | | |with | | |solution, | | |evolution | | |smell of | | |of peculiar| | |acetic acid. | | |odour. | | | | | | | |Bremen green, |Green |Unaltered.|Blackened. |Blackened. | |Brunswick green|solution and | | | | | |white residue. | | | | | | | | | | | | | | | | |Emerald green, |Dissolve to |Gradually |Become |Blackened | |Scheele’s green|greenish |coloured |brownish |and evolve | | |solution. |brownish |black. |garliclike | | | |yellow. | |odour. | | | | | | | |Copper borate |Dissolves to |Black |Becomes |Fuses. | | |greenish |residue. |brownish | | | |solution. | |black. | | | | | | | | |Rinmann’s green|Dissolves to |Unaltered.|Blackened. |Unaltered. | | |rose-red | | | | | |solution. | | | | | | | | | | |Chromium oxide |Almost |Unaltered.|Becomes dark|Unaltered. | | |unaltered. | |dirty green.| | | | | | | | |Chrome green |Becomes deeper |Unaltered.|Becomes dark|Unaltered. | | lake |in colour. | |dirty green.| |