296 
CYANIDE OP POTASSIUM. 
water, and becomes, on cooling, a crystalline mass, of a bril- 
liant white color. 
During the fusion brown flocculi are seen floating in the 
liquid, which finally unite together into a gray spongy mass. 
If the crucible be now withdrawn from the fire and allowed 
slightly to cool, it usually happens that the gray powder 
settles to the bottom: this deposit is facilitated by one 
or two stirrings with the glass rod. The hot and fused mass 
which swims above may be then decanted with great facility 
into a hot porcelain capsule, without admixture with the 
smallest quantity of the gray powder. 
The mass separated from the iron by decantation is a mix- 
ture of two combinations; the principal is cyanide of potas- 
sium, the other is cyanate of potassa. They are mixed in 
the proportions of five atoms of the former to one atom of the 
latter. 
The following is the reaction which takes place be- 
tween the ferrocyanide of potassium and the carbonate of po- 
tassa: 
At the commencement of the fusion, the cyanide of iron of 
the ferrocyanide of potassa, decomposes with the potassa of 
the carbonate of potassa into cyanide of potassium and proto- 
carbonate of iron, from which latter, at a more elevated tem- 
perature, the cyanide of potassium takes away all its oxygen, 
resulting in the formation of cyanate of potassa and metallic 
iron. 
If we consider the mixture to consist of two atoms of ferro- 
cyanide of potassium and two atoms of carbonate of potassa, 
we will have: 
Ferrocyanide of Potassium. Carbonate of Potassa. 
Cy 12 Fe 2 K 4 + K 2 2 2C0 2 = Cy 12 Fe 2 K 6 2 2C0 2 . 
and we will have, after fusion, 
Cyanide of Potassium. Cyanate of Potassa. Iron. Carbonic Acid. 
Cy ]C K 5 + Cy 2 0,KO Fe 2 2C0 2 
We obtain from two atoms of ferrocyanide of potassium 
