7 4° CHEMISTR Y OF RESPIRA TION. 
Speck l found, when be breathed a mixture of gases containing 1151 
per cent, of carbon dioxide, that 528 c.c. carbon dioxide were absorbed by 
the blood in a minute, whereas under normal conditions 230 c.c. of that 
gas would have been discharged. In a dog Pniiger 2 found that there 
were, under normal conditions, 29 - 8 volumes per cent, carbon dioxide 3 
in the arterial blood, but 56'8 volumes per cent, after the dog had 
breathed for one minute a mixture containing 70 per cent, oxygen 
and 30 per cent, carbon dioxide. Zuntz i observed an increase to 
89 - 6 volumes per cent, carbon dioxide when a dog breathed for one 
minute and a half a mixture containing 36'9 per cent, carbon dioxide. 
Numerous experiments were made by Paul Bert 5 upon the action of 
this gas upon different forms of life. He found that a percentage of 13 - 5 
to 17 was fatal for reptiles, 24 to 28 for sparrows, and 30 or more for 
mammals. When the air contained 30 to 40 per cent, of carbon dioxide, 
death resulted owing to the high tension of the gas in the blood ; thus in 
some dogs the percentage of carbon dioxide in the arterial blood was 
116, in the venous blood 120. Complete insensibility could be produced 
long before any danger to life arose, and thus the gas mixed with air 
or oxygen could be used for the production of anaesthesia, 6 
Carbon monoxide. — The physiological action of this gas is of the 
utmost practical importance, since it is every year the cause of 
numerous deaths in cases of poisoning from coal gas, the fumes of kilns 
and coke fires, and in the air of coal mines, especially after explosions. 
Although it has long been known that carbon monoxide is poisonous, 
it was about the year 1857 that Claude Bernard 7 and Hoppe-Seyler 8 
first pointed out that the carbon monoxide displaced the oxygen of 
the blood by forming a more stable compound with haemoglobin, and 
thus brought about asphyxia, 9 The action of this gas has been studied 
by many observers. 10 
The most recent investigations are those of Haldane, 11 who has 
experimented both upon himself and upon mice. The following are his 
chief conclusions: — The symptoms produced in man do not become 
sensible until sufficient carbonic oxide has been absorbed for the 
corpuscles to become about a third saturated ; with half saturation of 
the corpuscles the symptoms become urgent. The symptoms are due 
solely to deficiency in the percentage of oxygen in the blood, and are 
similar to those experienced by mountaineers and balloonists at high 
altitudes. The time required for the symptoms to appear in different 
animals is proportional to the respiratory exchange per unit of body weight, 
and is about twenty times as long in a man as in a mouse. Hence 
it is possible with safety to use a mouse as an indicator of the presence 
of poisonous proportions of carbonic oxide in the atmosphere of a coal- 
1 Centralbl. f. d. vied. Wissensch., Berlin, 1876, No. 17. 
2 Arch./, d. ges. Physiol., Bonn, 1868, Bd. i. S. 103. 
3 Measured at 0° and 1 m. 
4 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 408. 
5 "La pression barometrique," Paris, 1878, p. 982. This article, pp. 743-45. 
® See also Grediant, Compt. rend. Soc. de biol., Paris, 1887, p. 542. 
7 "Lecons sur les effets des substances toxiques et medicamenteuses," Paris, 1857, p. 
184 ; " Lecons sur les liquides de l'organisme," Paris, 1859, tome i. p. 365 ; tome ii. p. 427. 
8 Virchows Archiv, Bd. xi. S. 228 ; Bd. xiii. S. 104. 
9 This Text-book, article "Haemoglobin." 
10 Gaglio, Arch. f. exper. Path. u. Pharmakol. , Leipzig, 1887, Bd. xxii. S. 233 ; Gruber, 
Arch./. Hyg., Mtinchen u. Leipzig, 1883, Bd. i. S. 145; Welitschkowsky, ibid., S. 210; 
Fokker, ibid., S. 503 ; Greliant, "Les poisons de l'air," Paris, 1890. 
11 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 430. 
