A Dictionary of Arts (supplement): Prussian Blue.

(A Dictionary of Arts, Manufactures, and Mines; containing A Clear Exposition of Their Principles and Practice)
Recent improvements in
Arts, Manufactures, and Mines:
Being A supplement to his Dictionary
by Andrew Ure, M. D.,
F.R.S. N.G.S. M.A.S. LOND.; M. ACAD. N.S. PHILAD.; S. PH. SOC.N. GERM. HANOV.; MUHL. ETC., ETC.

Illustrated with one hundred and ninety engravings.

New York: D. Appleton & Company, 200 Broadway.  Philadelphia: George S. Appleton, 148 Chestnut St.
MDCCCXLVII
1847
PRUSSIAN BLUE. The following process deserves peculiar notice, as the first in which this interesting compound has been made to any extent, independently of animal matter. Mr. Lewis Thompson, of the Old Barge House, Lambeth, received a well-merited medal from the Society of Arts for this invention. He justly observes, that in the common way of manufacturing prussiate of potash, the quantity of nitrogen furnished by a given weight of animal matter is not large, and seldom exceeds 8 per cent.; and of this small quantity, at least one half appears to be dissipated during the ignition. It occurred to him that the atmosphere might be economically made to supply the requisite nitrogen, if caused to act in favorable circumstances upon a mixture of carbon and potash. He has found the following prescription to answer: Take of pearlash and coke, each 2 parts; iron turnings, 1 part; grind them together into a course powder; place this in an open crucible, and expose the whole for half an hour to a full red heat in an open fire, with occasional stirring of the mixture. During this process, little jets of purple flame will be observed to rise from the surface of the materials. When these cease, the crucible must be removed and allowed to cool. The mass is to be lixiviated; the lixivium, which is a solution of ferrocyanide of potassium, with excess of potash, is to be treated in the usual way, and the black matter set aside for a fresh operation with a fresh dose of pearlash. Mr. Thompson states that 1 pound of pearlash, containing 45 per cent. of alkali, yielded 1,355 grains of pure Prussian blue, or ferrocyanide of iron; or about 3 ounces avoirdupois.