\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.

{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.