444 Dr. Henry's Experiments on Ammonia. 
flame. The combustion, however, is not sufficiently vivid to 
render the process of any use in the analysis of ammonia. 
With nitrous oxide (containing only 5 per cent, impurity) 
ammonia forms a mixture which is extremely combustible. 
If the nitrous oxide be in excess, the proportions have a con- 
siderable range ; for any mixture may be fired by electri- 
city, of which the ammonia is not less than one-sixth of the 
whole. The combustion is followed by a dense cloud, some- 
times of an orange colour. When the nitrous oxide greatly 
exceeds the ammonia, ( as in the proportion, for example, of 
100 to 30) there is little or no diminution after firing : and 
the residuum is composed of a small portion of undecomposed 
oxide, some oxygen gas, and a considerable quantity of nitro- 
gen, the last of which, however, is not in its full proportion. 
When the nitrous oxide is further increased, still more oxygen 
is found in the residuum. 
When, on the contrary, the alkaline gas is redundant, com- 
bustion does not take place unless the nitrous oxide forms 
one-third of the mixture. A little diminution takes place on 
firing, but no cloudiness is observed ; and the residue is com- 
posed of hydrogen and nitrogen gases, with occasionally a 
small portion of undecomposed ammonia. As an example of 
what takes place, I select the following experiment from 
several others. 
A mixture of 41 measures of ammonia, with 40 of nitrous 
oxide(= 38 pure), in all 81 measures, were reduced by com- 
bustion to 75, which were found to consist of 16 hydrogen 
and 59 nitrogen gases. To explain this experiment, we may 
assume (as is consistent with your own analysis *) that 100 
* Researches, Res. ii. Div. 1, or Thomson’s System of Chemistry, 3d edit. ii. 143, 
