1824.] the Aeriform Compounds of Nitrogen. 301 



was used, some free oxygen was always detected in the re- 

 sidue ; and yet a slight redundancy of nitrous oxide appeared 

 to he 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 proportion 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 + 075 azote. 

 Nitrous oxide 2b' do. = 25*25 do. + 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. 



The nitrogen was by experiment 27*15 



By calculation it ought to have been, 



From the nitrous oxide 26 



Do. carbonic oxide *75 26*75 



Difference 0*40 



No person, I believe, who is much experienced in processes 

 of this nature, will look for a nearer approach to accuracy, than 

 in the results of the experiment which lias been just described ; 

 for the carbonic acid falls short by only -^ of the theoretical 

 proportion ; while the nitrogen exceeds that proportion by only 

 ■j^., and the oxygen by T '- . The experiment was several times 

 repeated, with approximations fully as near as the above to 

 those which the law of volumes would require. 



When the object in view is solely or chiefly to determine the 

 quantity of oxygen in nitrous oxide, there can be no source 

 of fallacy in the use of a slight excess of carbonic oxide. For 

 this purpose I made several experiments, which agreed so 

 closely in their results, that it may be sufficient to particularize 

 one of them as a specimen of the rest. 



Carbonic oxide 21 measures. 



-Nitrous oxide 19 do. = 18*4 pure 4- 0*6 nitrogen. 



40 



40 after combustion. 



21*5 after potash ; containing no free oxygen. 



