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



Oxygen in the 307 cubic inches of gas : 



Before the experiment 245.59 



Found after experiment 195.61 



In carbonic acid gas 21.27 



216.88 



Loss of oxygen 28.71 



This agrees with the facts stated in our former paper in the experiment with 



the guinea-pig ; but there is a striking difference in the case of the carbonic 



acid; so far from there being an increase of it when the pigeon breathed oxygen, 



there was a considerable diminution. 21.27 -J- 72' = .29 of a cubic inch per 



minute, which is little more than a quarter of a cubic inch per minute ; but 



he produced more than half a cubic inch in the same time when he breathed 



common air ; and with regard to the increase of the azote, we may remark 



that at the end of the first period of 22 minutes, rather less tlian ten cubic 



inches of azote were left, for 



56 69 + 1.50 = 58.19 azote before 1 ^ ^^ ^^^ ^^j ^^^j ^^^^^ l^^t 



and 48.22 a2ote after J ° 



In the following period of 2 1 minutes none of the original azote was left, 

 but there was an increase of about 13 cubic inches. In the next period of 23 

 minutes only 1.44 of azote was admitted, but 10.90 were found; thus 10.90 — 

 1.44 = 9.46 of azote evolved in that time ; it seems therefore plain that oxygen 

 must have been absolved by the blood in the lungs, and a corresponding 

 volume of azote given out. 



Second experiment with oxygen gas. 



The oxygen gas was made as before from chlorate of potash, and contained 

 in this instance only one per cent of azote. 



Barom. 30.50, therm. 45°. The quantity of atmospheric air with the pigeon 

 in the intermediate vessel was 69 cubic inches ; during the first 20 minutes 62 

 cubic inches of oxygen were supplied. In about a quarter of an hour he began 

 to open his beak, pant, shake his head and appear uneasy, frequently drawing 

 the film over his eyes, and often putting out his tongue, the respiration be- 

 coming quicker. When he had been in about 40 minutes his beak reddened 



