The Collaborative International Dictionary of English v.0.48:
Ferrocyanide \Fer`ro*cy"a*nide\ (? or ?; 104), n. [Ferro- +
cyanide.] (Chem.)
One of a series of complex double cyanides of ferrous iron
and some other base.
[1913 Webster]
Potassium ferrocyanide (Chem.), yellow prussiate of potash;
a tough, yellow, crystalline salt, K4(CN)6Fe, the
starting point in the manufacture of almost all cyanogen
compounds, and the basis of the ferric ferrocyanate,
prussian blue. It is obtained by strongly heating together
potash, scrap iron, and animal matter containing nitrogen,
as horn, leather, blood, etc., in iron pots.
[1913 Webster]