Characters. - In large yellow four-sided tablets or prisms, permanent in the air.

Solubility. - Soluble in water, insoluble in alcohol.

Reactions. - The aqueous solution precipitates deep blue with persulphate of iron, brick-red with sulphate of copper, and white with acetate of lead. Heated with diluted sulphuric acid, hydrocyanic acid vapours are evolved.

Peeparations foe which Ferrocyanide of Potassium is used. Acidum Hydrocyanicum Dilutum, Potassii Cyanidum.

Test solution of Ferrocyanide of Potassium. Dissolve 1/4 ounce of ferrocyanide of potassium (yellow prussiate of potash) in crystals in 5 fluid ounces of distilled water and filter, B.P.; 1 in 10 of water, U.S.P.

Test solution of Ferricyanide of Potassium. Dissolve 1/4 ounce of ferricyanide of potassium (red prussiate of potash) in crystals in 5 fluid ounces of distilled water and filter, B.P.; 1 in 10 of water, U.S.P.