84 



risen nearly half an inch into the jar, which was 

 thickly moistened with vapour, and the breathing of 

 the animal seemed rather languid : by the twenty- 

 first hour, he breathed very faintly ; and, by the 

 twenty-fourth hour, he had ceased to breathe. The 

 jar was allowed to stand some hours, at the end of 

 which time, the mercury stood about eight-tenths of 

 an inch high, and one-tenth of an inch of fluid was 

 deposited on its surface. The jar was now raised, 

 and diluted sulphuric acid being poured into the al- 

 kaline solution, excited in it a verybrisk effervescence. 

 It is inferred, therefore, from these experiments, that 

 the oxygenous portion of the air almost entirely dis- 

 appears during the respiration of these animals, after 

 which they cease to breathe ; and that a large por- 

 tion of carbonic acid is at the same time produced. 

 69. Proceeding on the supposition, that the loss 

 in the bulk of air, evinced by the ascent of the mer- 

 cury, in the last of the foregoing experiments, arose 

 from the attraction of the carbonic acid by the al- 

 kaline solution, we endeavoured to ascertain the 

 proportion which this loss of bulk bore to that of 

 the whole air originally employed. With this view, 

 a frog was procured, and placed in a jar of the ca- 

 pacity of forty cubic inches. Under the hoop which 

 supported him, about half way up the jar, was placed 

 a small cup, containing one cubic inch of the water 

 of potassa, and the jar being then filled with atmo- 

 spheric air, was inverted into a dish of mercury, and 

 kept steady by a weight pressing upon it. In the 

 room in which the animal was placed, the barometer 

 stood at 29.2 inches, and the thermometer at 61. 

 At the end of twenty-nine hours, the animal was 



