284 MESSRS. ALLEN AND PEPYS ON THE RESPIRATION OF BIRDS. 



In the first period of 20 minutes the azote before respiration was 



54.51 + 62 = 55.13 

 Azote found 42.33 



Azote left 12.80 



Second period of 21 minutes. 

 ■'^'^**'' 12.80 + 86 =■ 13.66 

 Azote found 19.80 



Increase of azote 6.14 



Third period of 29 minutes. 



Azote in 84 cubic inches of oxygen . . . .84 

 Found 8.56 + .71 + 7 = 16.27 



Increase of azote 15.43 



15.43 + 6.14 = 21.57 total increase of azote. Here the loss of oxygen exactly 

 equals the increase of azote. 



Mixture of hydrogen and oxygen. 



We next tried the etFects of an artificial atmosphere, substituting hydrogen 

 for azote ; the oxygen made as before contained 3 per cent of azote, and deto- 

 nating 10 parts of it with 20 of hydrogen in Volta's eudiometer, the whole 

 volume of gas disappeared except about one part which was azote, and this 

 confirmed the result with the other eudiometer and green sulphate of iron 

 satiirated with nitrous gas. 



There were but 64 cubic inches of common air this time in the intermediate 

 vessel containing the pigeon at the beginning of the experiment, and 187 cubic 

 inches of a mixture of hydrogen and oxygen, in which the oxygen was in 

 about the same proportion to the hydrogen as it is to the azote in the common 

 air, were gradually passed through the intermediate vessel during 26 minutes. 



Duration of 

 the expt. 



at 55' after 2 p.m. the pigeon was put into the vessel with common air ; 

 moisture almost immediately began to condense on 

 the inside of the glass. 



