443 
Dr. Henry’s Experiments on Ammonia. 
fact as contradicting the accuracy of the proportions which 
you have assigned ; and it appears to me that a sufficient 
reason may be given for the want of a more perfect coinci- 
dence between results, obtained by such different methods of 
investigation. In the products of the electrization of am- 
monia, the hydrogen composes nearly three fourths of the 
mixture ; and hence its combustion by oxygen gas is likely to 
be completely effected, and the whole of the hydrogen con- 
densed into water. But after the partial combustion of am- 
monia, by oxygen gas, a residuum is left of hydrogen and 
nitrogen gases, of which the hydrogen usually composes less, 
and sometimes considerably less, than one half the bulk. In 
this case, it may be suspected that a small quantity of hydro- 
gen occasionally escapes being burned ; and whenever this 
happens, its proportion to the nitrogen will appear to be less 
than the true one.* 
From the inflammability of a mixture of ammonia with 
oxygen gas, it was natural to expect that this alkali would 
prove susceptible of slow combustion. By means of a pecu- 
liar apparatus (on a plan which I have described in the Philo- 
sophical Transactions for 1808, part II. but on a smaller scale, 
and with the substitution of mercury for water), I have found 
that ammonia, expelled from the orifice of a small steel 
burner, may be kindled by electricity in a vessel of oxygen 
gas ; and that it is slowly consumed with a pale yellow 
* This consideration suggests the propriety of using no more oxygen in the first 
combustion of ammonia, than is barely sufficient to inflame it ; or if a larger quan- 
tity has been used than is required for this putpose, and a residue consequently ob- 
tained, of which the hydrogen forms only a small proportion, it is proper to add a 
farther quantity of hydrogen, before the second combustion. An allowance may, 
afterwards be made for this addition. 
