282 MESSRS. ALLEN AND PEPYS ON THE RESPIRATION OF BIRDS. 
Oxygen in the 30/ 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 -5- 72 f = .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 than ten cubic- 
inches of azote were left, for 
= 9.97 of the original azote left. 
In the following period of 21 minutes none of the original azote Avas left, 
but there was an increase of about 13 cubic inches. In the next period of 23 
minutes only 1.44 of azote Avas admitted, but 10.90 Avere 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 Avith 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 Avith the pigeon 
in the intermediate vessel Avas 69 cubic inches ; during the first 20 minutes 62 
cubic inches of oxygen Avere supplied. In about a quarter of an hour he began 
to open his beak, pant, shake his head and appear uneasy, frequently draAving 
the film over his eyes, and often putting out his tongue, the respiration be- 
coming quicker. When lie had been in about 40 minutes his beak reddened 
56.69 + 1.50 = 58.19 azote before I 
and 48.22 azote after J 
