Copper Reds
:
ON THE PRIMARY, RED.
A somewhat finely coloured red oxide is produced by exposing to a white
heat for twenty minutes, a mixture of certain proportions of blue
vitriol, mono-carbonate of soda, and copper filings. The product,
however, is affected by impure air, and is otherwise not so desirable as
an iron oxide.
An interesting account has lately been given by Professor Church of a
new animal pigment, containing copper, found in the feathers of the
violet plantain-eater and two species of Turacus, natives respectively