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. Trans., 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. dechim. etphys., Paris, 1841, Se>. 3. tome ii. p. 538 ; Wertheim, Dcutsches 
Arch. f. klin. Med., Leipzig, Bd. xv. ; Wien. med. Wchnschr., 1878 ; Vierordt, "Physiol, 
d. Athmens," Karlsruhe, 1845 ; E. Smith, Phil. Trans., London, 1859, vol. cxlix. p. 682; 
Speck, "Untersuch. ueber Sauerstoffverbrauch u. Kohlensaureausathinung d. Menschen," 
Cassel, 1871 ; Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. ii. S. 405 ; Bd. xii. 
S. 1 ; Lossen, Ztschr. f. Biol., Munchen, 1866, Bd. ii. S. 244 ; Berg, Deutsches 
Arch. f. klin. Med., Leipzig. 1869, Bd. vi. S. 291; Leyden, ibid., Bd. vii. S. 536; 
Andral and Gavarret, " Recherches sur l'acide carbonique exhale^" Paris, 1843; 
Marcet, Phil. Trans., London, 1890, B. ; Proc. Roy. Soc. London, 1891, vol. xlix. 
p. 103 ; Jolyet, Bergonie, and Sigalas, C'ompt. rend. Acad. d. sc, Paris, 1887, tome cv. 
p. 380. 
Lbwy's respiration apparatus. 
