152 



cipally of oxygen, which was inverted over 

 ry : in an hour and a quarter, the animal breathed 

 with much difficulty, and, being removed, the air 

 was examined, and found to be diminished in bulk 

 by eight cubic inches : 4O cubic inches more were 

 attracted by the water of potassa, and consequently 

 consisted of carbonic acid; from which it appears, 

 that the volume of acid produced, was one-sixth less 

 than that of oxygen gas which had disappeared *. 

 In a second experiment, another animal of the same 

 species was confined an hour and a half in a cubic 

 foot, or 1728 cubic inches, of oxygen gas, inverted 

 over mercury : the gas suffered a diminution of 55 

 cubic inches, and 229.5 cubic inches more were at- 

 tracted by the water of potassa, leaving a residue of 

 pure oxygen "h hence, therefore, the whole loss which 

 the oxygen gas experienced, amounted to 284.5, 

 while the quantity of acid produced was only 229.5, 

 or was ^ less in volume than the oxygen which 

 had disappeared. In these experiments, however, 

 the air breathed was not natural to the lungs, and 

 the confinement of the animal was prolonged until 

 he breathed with difficulty, which, on the principles 

 already stated (92.), would necessarily increase the 

 volume of residual air in the lungs, and render the 

 apparent diminution greater than it ought to be. 

 In the experiments made by Mr Davy on his own 

 respiration, the oxygen gas that disappears every 

 minute, is estimated at 31.6 cubic inches, and the 



* Mem. A cad. 178O. 



y Ann. de Chimie, t. v, p. 261. et seq. 



