Cobalt Prussian Blue
:
ON THE PRIMARY, BLUE.
Gmelin states that yellow prussiate of potash yields with a solution of
oxalate of sesquioxide of cobalt a blue resembling Prussian blue--that,
in fact, there can be obtained a Prussian blue with a base of cobalt
instead of iron. In the moist state, the similarity is sufficiently
great, but when washed and dried, the product is, with us, a dingy slate
colour. Possibly, if such a blue could be produced, it might exceed in
permanence the ferro- and ferri-cyanides of iron. Of course the compound
would be much more expensive.