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.



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