4,38 Mr. Henry’s Experiments on Ammonia. 
the nitrogen generally falls short of the proportion, which 
ought to accrue from a given weight of ammonia ; and hence 
it is scarcely possible to attain, when a considerable excess of 
oxygen is used, an accurate analysis of the volatile alkali. 
When, on the contrary, the ammonia exceeds considerably 
the oxygen gas, no production of nitrous acid appears to take 
place ; for the residue, after detonation, is quite free from 
cloudiness. It is remarkable, however, that ammonia when 
'fired, in certain proportions, with less oxygen than is required 
to saturate its combustible ingredient, is nevertheless com- 
pletely decomposed. Part of its hydrogen is sufficient for the 
saturation of the oxygen; and the remaining hydrogen, and 
the whole nitrogen of the ammonia, together with that exist- 
ing as an impurity in the oxygen employed, remain in a 
gaseous state, and compose a mixture, which may be inflamed 
by adding a second quantity of oxygen gas, and passing an 
electric spark.* In this way all the hydrogen of the volatile 
alkali may be saturated with oxygen, and condensed into 
Water ; and the whole of the nitrogen may be obtained as a 
final result of the process. After determining the amount of 
the oxygen, consumed both in the first and second combus- 
tions, it is easy to calculate the quantity of hydrogen, in the 
saturation of which it has been employed ; for when no nitrous 
acid has been formed, the hydrogen will be, pretty exactly, 
double in volume the oxygene which has been expended. 
* This is analogous to what happens, when ether, alcohol, or any of the aeriform 
compounds of carbon and hydrogen, are exploded with a deficient proportion of oxy- 
gen ; for much of the hydrogen is found in the residuum in the state of gas, and again 
becomes susceptible of combustion after the addition of a second quantity of oxygen. 
(See Mr. Cruickshank’s excellent papers in the 5th Volume of Nicholson’s 
Journal, 4*0.) 
