6 9 8 



CHEMISTRY OF RESPIRATION. 



The moisture is absorbed by pumice saturated with sulphuric acid, 

 and the carbon dioxide is removed by soda lime, which has been proved 

 to be such a rapid and excellent absorbent that the total output of 

 carbon dioxide can be determined directly. 1 The animal is weighed in 

 the closed chamber before and after the experiment, and thus there is 

 no need to calculate the respiratory exchange during that process, and 

 no error arises from the deposition of moisture. The air entering the 

 chamber is freed from carbon dioxide and moisture, and therefore all 

 the moisture and carbon dioxide in the air leaving the chamber come 



from the animal. The 

 intake of oxygen is 

 determined indirectly ; 

 the animal gives off 

 only carbon dioxide 

 and water, it absorbs 

 only oxygen, and the 

 amount absorbed is 

 found by subtracting 

 the loss in weight of the 

 chamber and animal 

 from the total loss of 

 carbon dioxide and 

 water. 



Haldane's method 

 has also been adopted 

 for the determina- 

 tion of the respira- 

 tory exchange of small 

 animals and of chick 

 embryos. 2 



Another method, 

 which has been used 

 for the observation of 

 the respiratory ex- 

 change in man, is the 



determination of the volume of air respired during a limited period, 

 and then, from analysis of samples of the inspired and expired air, 

 estimating the intake of oxygen and the output of carbon dioxide 

 and water. 3 The more recent and exact forms of apparatus con- 



1 Haldane and Pembrey, loc. cit. 



2 Pembrey, Journ. PhysioL, Cambridge and London, 1894, vol. xv. p. 401 ; 1894-95, 

 vol. xvii. p. 331. 



3 Davy, "Researches," p. 431 ; Ann. d. Phys. u. Chem., Leipzig, Bd. xix. S. 298 ; Allen 

 and Pepys, Phil. Trails., London, 1808, p. 250 ; 1809, p. 404 ; Prout, Ann. Phil., London, 

 1813, vol. ii. p. 330 ; vol. iv. p. 331 ? Journ. f. Chem. u. Phys., Ntirnberg, 1814, Bd. xv. ; 

 MacGregor, Ann. de chim. etphys., Paris, 1841, Ser. 3. tome ii. p. 538 ; Wertbeim, Deutsches 

 Arch. f. klin. Med., Leipzig, Bd. xv. ; Wien. med. Wchnschr., 1878 ; Vierordt, "Physiol. 

 d. Athrnens." Karlsruhe, 1845 ; E. Smith, Phil. Trans., London, 1859, vol. cxlix. p. 682; 

 Speck, "Untersuch. ueber Sauerstoffverbraucb u. Kohlensaureausathnivmg d. Menschen," 

 Cassel, 1871 ; Arch. f. exper. Path. u. PharmaJcoL, Leipzig, Bd. ii. S. 405; Bd. xii. 

 S. 1 ; Lessen, Ztschr. f. BioL, Miinchen, 1866, Bd. ii. S. 244 ; Berg, Deutsches 

 Arch. f. Jdin. Med., Leipzig. 1869, Bd. vi. S. 291; Leyden, ibid., Bd. vii. S. 536; 

 Andral and Gavarret, " Recherches sur 1'acide carbonique exhale"," Paris, 1843; 

 Marcet, Phil. Trans., London, 1890, B. ; Proc. Roy. Soc. London, 1891, vol. xlix. 

 p. 103 ; Jolyet, Bergonie', and Sigalas, Compt. rend. Acad. d. sc., Paris, 1887, tome cv. 

 p. 380. 



FIG. 66. Lowy's respiration apparatus. 



