278 
POTASSIUM AND SODIUM. 
with three equivalents of hydrogen to form an equivalent of 
ammonia, and the carbon is separated. 
2d. When ammonia is exposed to carbon at a full red 
heat, an equivalent of ammonia exchanges two of its equi- 
valents of hydrogen for two equivalents of carbon, and thus 
becomes prussic or hydrocyanic acid. 
3d. If free potassium or sodium be also present, the 
equivalent of ammonia parts with all its three equivalents 
of hydrogen, and the nitrogen which remains takes in their 
place two equivalents of carbon to form cyanogen, and one 
equivalent of potassium or sodium, as the case may be, to 
form a cyanide of the metallic base. 
4th. When animal matter is exposed to heat, its tempe- 
rature becomes gradually increased to low redness before 
it assumes that high temperature indicated by a full red 
colour; therefore, whenever animal matter is subjected to 
what is called destructive distillation, the formation of am- 
monia must take precedence, in point of time, to that of 
prussic acid or of the cyanides. 
5th. When the oxide of potassium, or of sodium, or the 
carbonate of either of those oxides, is intimately mixed with 
carbon, and exposed to a heat approaching to whiteness, 
its metallic base is set free from the oxygen with which it 
was'previously combined, and rises in vapour. If ammonia 
comes into contact with the mixture of. carbon and alkali, 
or of carbon and alkaline carbonate, the separation of the 
metallic base from its oxygen takes place at a lower tempe- 
rature — under such circumstances, a full red heat being suf- 
ficient. In the case of the carbonates, the metallic bases, 
potassium and sodium are liberated from the carbonic acid 
also, whenever they separate from their oxygen. 
6th. Cyanide of potassium, or cyanide of sodium, by ex- 
changing an equivalent of every three equivalents of its base 
for an equivalent of iron, is converted into the correspond- 
ing ferrocyanide, or what is called, in commerce, prussiate 
of potash, or prussiate of soda; and this change may be ef- 
