61 6 FUNCTIONS OF ANIMALS. 



ascertained that the air expired by persons ill of confluent small- 

 pox contained as much as eight per cent, of carbonic acid gas. 

 During the eruptive fever of measles it amounted to from four 

 to five per cent. In proportion as health was resumed, the 

 per centage diminished. In chronic skin diseases, an aug- 

 mentation was also observed, and in one case of ichthyosis the 

 mean per centage was 7*2. In diabetes, no aberration could be 

 detected. * 



A set of experiments upon the same subject has been publish- 

 ed by Mr Coathupef in 1839. His apparatus was simple and 

 excellent, and the experiments appear to have been conducted 

 with great care. They were continued for a week. The fol- 

 lowing is the result obtained : 



Mean, 4-02 



These experiments do not agree with Dr Prout's, and show 

 the necessity of repeating them upon many individuals before 

 any general conclusions can be drawn. 



From the experiments of Prout, it appears that the quantity 

 of carbonic acid gas produced by respiration is at its maximum 

 at noon, and that its quantity at 1 1 A. M. is to the mean quantity 

 for twenty-four hours as 3*92 to 3*45. Hence it follows that the 

 mean volume of carbonic acid gas in 100 volumes of air expired, 

 deduced from the preceding experiments, is 3*72. 



From the experiments of Boussingault, it would appear that 

 a cow in twenty -four hours discharges by the lungs about five 

 times as much carbon as a man does.f A horse discharges 

 about six times as much. 



Now, if the preceding estimate of the quantity of air drawn 



* Atheneum, No. 677, p. 822. + Phil. Mag. (3d series), xiv. 401. 



| Ann. de Chim. et de Phys. Ixxi. 126, 



