The goods, previously polished and finished, are heated to a bright-red, and rubbed or sprinkled over with prussiate of potash.
As soon as the prussiate appears to be decomposed and dissipated the articles are plunged into cold water.
Might you not have used potassium cyanide or prussiate of potash?
A prussiate of iron is obtainable of a violet hue, affording good shadow tints and clear pale washes.
I have a peculiar kind of steel which I cannot harden by fire and water, neither will it caseharden by prussiate of potash.
The piece being heated may then, if small, be dipped in the prussiate of potash, or if large have the same spread upon it.
A mordant of blue vitriol is commonly first given, followed by a bath of prussiate of potash.
Ecru: Continue the foregoing operation for blue by passing the goods through a solution of prussiate of potash.
To a solution of sulphate of iron add a drop or two of a solution of prussiate of potash, and a blue colour will be produced.
A very good black is the prussiate or steam aniline black whose cheapness should recommend it.
