186 REPORT—1845,. 
in contact with the glowing fuel, and that it owes its formation to a direct union 
of carbon with potassium and nitrogen of the air. 
Our experiments have further shown that cyanide of potassium is volatile 
at high temperatures, and this property is of much influence in the part which 
it takes in the reducing process of the furnace. Carried up by the ascending 
eurrent of gas, the cyanide of potassium, partly in a state of vapour, partly 
as a solid, reaches the region of the furnace in which the reduction is effected, 
and here it exerts its well-known reducing power. In consequence of this 
it is decomposed into nitrogen, carbonic acid, and carbonate of potash, the 
former of which passes up with the ascending gaseous column to the mouth 
of the furnace, while the latter, not being volatile, falls back with the other 
materials in the furnace to that point where it is again converted inte cyanide 
of potassium, under the influence of the carbon and nitrogen. Hence a large 
quantity of ore may in this way be reduced in the lower part of the furnace, 
by comparatively a small quantity of regenerated cyanide of potassium. The 
importance of this view of the part played by cyanide of potassium, although 
previously entirely neglected, will be seen when we consider that this power- 
ful reducing agent must accumulate in the furnace to a considerable extent. 
The region of the furnace where the highest temperature prevails forms a 
limited space, beyond which the cyanide of potassium cannot extend to the 
lower parts of the furnace until its quantity is so much increased by the pot- 
ash descending in the materials supplied that the excess of cyanide of potas- 
sium escapes volatilization and reaches the blast, where it is burnt and con- 
verted into nitrogen, carbonic acid and carbonate of potash, the basis of which 
unites with the slag. We have already shown that the relation of the nitro- 
gen to the oxygen in the gaseous mixture, collected only two and a half feet 
over the tuyére, is 79°2 : 22°8, after deducting a quantity of oxygen corre- 
sponding to the hydrogen. If the gas generated at this place contained only 
the nitrogen and oxygen due to the air, the proportion would be 79°2: 20°8 ; 
and hence it follows that the gases at this point must either have obtained 
oxygen from a source independent of the air, or that a proportion of nitrogen 
has been abstracted from them. Any one who has had the opportunity of 
observing the temperature of the furnace at this part will at once agree with 
the opinion that the excess of oxygen cannot be derived from the carbonic 
acid or iron ore. A simple inspection of the materials enables us to reject 
such an explanation as erroneous, for the fused materials flowing from the fur- 
nace do not evolve gas, although they come from a point in the immediate 
vicinity of that where the oxygen has been taken up. 
We must therefore admit'that this pheenomenon is connected with the for- 
mation of cyanide of potassium in the furnace. The potash, as it yields its 
oxygen to carbon during its conversion to cyanide of potassium, assumes for 
every volume of oxygen lost by it two volumes of nitrogen in the form of 
cyanogen, and consequently the proportion of nitrogen to oxygen is neces- 
sarily increased. 
