POTASSIUM AND SODIUM. 
279 
fected by causing the cyanides of the respective metals, dis- 
solved in water, to come into contact with iron, or oxide of 
iron, in a state of division. 
The ordinary way of combining potassium or sodium with 
cyanogen, preparatory to making the prussiate of potash, 
or prussiate of soda, for commerce, is to expose in iron pots 
an impure carbonate of one of those alkalies and animal 
matter to a red heat, and to trust for the necessary contact 
of the nitrogen and carbon of the animal matter with the 
metallic element, to the thorough incorporation of the in- 
gredients of the pasty mass by stirring. While the tempe- 
rature of the animal matter is approaching redness, ammo- 
nia is constantly being generated, and as it is volatile, it es- 
capes and is lost; and this continues until the heat becomes 
great enough to convert the nitrogen and carbon of the ani- 
mal matter into cyanogen, and to fix that cyanogen, by 
combining it with the metallic base of the alkali. Another 
source of loss is, the difficulty of causing the different ele* 
ments contained in the pasty mass to combine; for, before 
each can be brought into contact with the other, by mecha- 
nical agitation, their temperature becomes elevated, and 
great part of the resulting nitrogenous gases, which are 
volatile, have time to escape. There is a third evil attend- 
ing the ordinary process, namely, the proportion of carbon 
in animal matter, compared to its nitrogen, is greater than 
that in the alkaline cyanides; the greater part of this carbon, 
from its fixed nature, remains to solidify the mass from which 
the nitrogen so freely escapes; so that it becomes necessary 
to suspend the addition of the animal matter, on account of 
the mass being too solid for the chemical action to go on 
before enough of nitrogen has been combined to convert 
much of the alkali into prussiate. 
Two patents have already been granted for methods of 
preventing the losses sustained in the ordinary way of 
making the prussiates of potash and soda. By one of these 
methods the ammonia which is liberated from a heated 
