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XXII. On the respiration of birds. By William Allen and William Hasle- 
dine Pepys, Esqrs. Fellows of the Royal Society. 
Read April 30, 1829. 
Our communications to the Royal Society, as printed in the Phil. Trans, 
for 1808 and 1809, detailed the effects produced when the human subject or a 
guinea-pig respired, either atmospheric air alone, or pure oxygen, or a mixture 
of hydrogen and oxygen. We thought it would render the subject more com- 
plete if we extended our inquiries to the respiration of birds, and accordingly 
made several experiments with pigeons in the same apparatus that we employed 
for the guinea-pig. The apparatus is engraved and described in the Phil. Trans, 
for 1809, page 429. 
First experiment with atmospheric air. 
A pigeon was placed in the intermediate glass vessel, in 62 inches of air on 
the mahogany stand over quicksilver, between the two gasometers communi- 
cating with the vessel in which the pigeon was confined. One of the gaso- 
meters was empty, but connected by tubes and stop cocks with the quicksilver 
bath, and also with the intermediate vessel ; the other contained the air for the 
supply of the pigeon. The barom. being 30.130, the therm. 54°, during 69 mi- 
nutes, at intervals of four or five minutes, 35 cubic inches at a time of com- 
mon air were slowly passed through the vessel in which the bird was con- 
fined ; the other gasometer of course received what was pushed off, the quan- 
tity was noticed by its register, and a portion was received by a bottle in the 
quicksilver bath for examination ; in this way 525 cubic inches of common air 
were supplied, to which the 62 cubic inches in the intermediate glass vessel 
being added, made a total of 587 cubic inches in which the pigeon had respired 
for 69 minutes. The registers of both gasometers agreed throughout to a very 
trifle, which confirmed our former observations, that there is no change in the 
volume of atmospheric air when respired under natural circumstances. 
