502 On the Analysis of the 
washed with caustic potash, appeared, from 
the results of its combustion with oxygen, to 
be contaminated with not more than 3 per 
cent of foreign gas, having the properties of 
nitrogen. Some nicety was found to be ne- 
cessary in adjusting the proportions of the 
gases to each other, in order to obtain a per- 
fect decomposition. When an excess of ni- 
trous oxide was used, some free oxygen was 
always detected in the residue; and yet a 
slight redundancy of nitrous oxide appeared 
to be essential to the perfect combustion of 
the carbonic oxide. After firing the mixed 
gases, and removing the carbonic acid by 
liquid potash, I next determined the propor- 
tion of oxygen in the residue by commonly 
known methods, and considered the remainder 
as nitrogen gas. An example, taken from an 
experiment made with great care, will best 
illustrate the nature of the process. 
Carbonic Oxide 25 measures = 24.25 pure + 0.75 azote. 
Nitrous Oxide 26 do. = 25.25 pure+ 0.75 do. 
51 
52 after combustion. 
28 after potash; found to consist of 0.85 
oxygen + 27.15 nitrogen. 
In this case, the carbonic acid, from 24.25 
real carbonic oxide was 24 measures. 
