7 16 
CHEMISTR Y OF RESPIRA TION. 
E. Smith. 1 He found that a man produced 1616 c.c. of carbon dioxide per 
minute when he was perfectly at rest, as in a deep sleep ; that during a 
walk at the rate of two miles (3048 metres) an hour, the discharge of 
carbon dioxide was increased to 569 - 5 c.c, and to 851-2 c.c. when the 
rate of walking was quickened to three miles (45 71 '9 metres) an hour. 
The greatest increase, 158T9 c.c, of carbon dioxide per minute, was 
caused by work upon a treadmill. 
In 18GG, Pettenkofer and Yoit 2 performed a series of important 
observations upon the metabolism of healthy men, under different con- 
ditions as regards work and diet, and they found that if unity represent 
the value of the output of carbon dioxide and the intake of oxygen 
when the man is at rest, then work brings about the following 
results : — 
During Hunger, 
Moderate Diet 
Carl ion dioxide 
2-3 
1-6 
en . 
2-1 
1-8 
The numerous experiments made by Speck, 3 under different con- 
ditions as regards the amount and nature of the work performed, show 
that the air inspired, the oxygen absorbed, and the carbon dioxide 
discharged, are greatly increased; the percentage composition of the 
expired air is but little altered, and the respiratory quotient increases 
slightly during the work. Hanriot and Kiehet 4 find for each kilo- 
grammetre of wm-k performed by a man, an increase of 3468 c.c. in the 
oxygen absorbed, and 4*221 c.c. in the carl ion dioxide discharged. 
In experiments upon horses, Zuntz and Lehmaun 5 obtained the 
following results : — 
Litres per Minute. 
CO, 
0„. 
Air expired. 
Carbon Dioxide 
discharged. 
Oxyg-en absorbed. 
Rest 
44 
1-478 
1-601 
•92 
Walk 
177 
4-342 
4-766 
■90 
Trot 
333 
7-516 
8-093 
•93 
It is impossible here to discuss fully the quantitative relationship 
between metabolism and work, but the conclusions reached by Katzen- 
stein 6 are as follows : — The work performed by the arms in turning a 
wheel produces, per unit of work done, a greater increase in the respiratory 
exchange than walking or climbing; the absorption of oxygen is per unit 
of work performed somewhat greater for light, than for heavy work : 
the absorption of oxygen and the discharge of carbon dioxide increase 
1 Phil. Trans.. London, 1859, vol. cxlix. pt. 2, p. 6S1. 
- Ztschr. f. Biol., Miinchen, 1866, Bd. ii. S. 459. See also this article, p. 718, and 
article by Voit in Hermann's "Handbuch," Bd. vi. Th. 1, S. 201. 
3 Dewtsches Arch../, klin. Med., Leipzig, 1S89, Bd. xlv. S. 461. 
4 Compt. rend. Acad. d. sc, Paris, 1887, tome civ. p. 1S65 ; tome cv. p. 76. 
5 Landw. Jahrb., 1889, Bd. xviii. S. 1 ; Joum. Physiol., Cambridge and London, 1S90, 
vol. xi. p. 396. 
6 Arch. f. d. ejes. Physiol., Bonn, 1891, Bd. xlix. S. 380. 
