r66 
CHEMISTR Y OF RESPIRATION. 
that the gases of the blood were present in a state of loose chemical 
combination with si ime unknown constituent of the blood, in a similar 
way to that in which carbon dioxide is combined in solutions of sodium 
phosphate. A few years later, Lothar Meyer l came to a similar con- 
clusion, for he found that the amount of oxygen retained in the bipod 
only varied slightly with alterations of pressure. About the same time 
Fernet 2 observed that the amount of oxygen chemically combined in 
blood saturated with air was about five times greater than the quantity 
which could be dissolved at the ordinary atmospheric pressure: this 
oxygen was, moreover, chiefly contained in the red corpuscles. 
A further proof of the chemical combination of oxygen was obtained 
wlien Bernard 3 and Hoppe-Seyler 4 discovered that the oxygen of the 
blood could be displaced by an equal volume of carbon monoxide, a gas 
which formed a more stable combination with the blood. The most con- 
vincing proof, however, was furnished when Hoppe-Seyler succeeded in 
crystallising haemoglobin, and showed that it combined with oxygen, but 
yielded up the gas to a vacuum ; he also showed that the haemoglobin, 
for so he named the pigment of the red corpuscles, had a definite spectrum. 
A year or two later, in 1864, Stokes 5 discovered that reducing sub- 
stances removed oxygen from the haemoglobin and effected a marked 
change in its colour and spectrum. 
The physical and chemical properties of haemoglobin are described 
fully in another part 6 of this work ; here it is only necessary to discuss 
the part which the pigment plays in the processes of respiration. 
The coefficient of absorption of blood for oxygen is a little lower than 
that of water, for the presence of salts in solution diminishes the capacity 
of the liquid to absorb gases. 7 The following table shows the volume of 
Temperature. 
Oxygen Absorbed 
according to different ( (bservers. 
Bunsen. s 
Winkler.9 
Hiifner.™ 
0° 
5° 
10° 
15° 
20° 
25° 
30° 
40° 
50° 
0-04114 
0-03628 
0-03250 
0-02989 
0-0283S 
0-04890 
0-04286 
0-03802 
0-03415 
0-03103 
0-02844 
0-02616 
0-02306 
0-02090 
0-02844 
0-02745 
0-02635 
0-02447 
1 "Die Gase des Blutes," Diss., Gottingen, 1857 ; Ztschr. f. rat. Med., Bd. viii. S. 256. 
3 Ann. d. sc. not., Paris, 1857, Sen 4, Zool., tome viii. p. 125; Journ. de physiol. 
expe'r., Paris, 1860, tome iii. 
3 "Lecons sur les ett'ets des substances toxicities et medicamenteuses," Pans, 185/, p. 
184 ; "Lecons sur les liquides de l'organisme," Paris, 1859, tome i. p. 365 ; tome ii. p. 427. 
4 Virchow's Archiv, Bd. xi. S. 288 ; Bd. xiii. S. 104. 
5 Proc. Roy. Soc. London, vol. xiii. p. 357. 
<; Article " Hremoglobin," this Text-book, vol. i. 
7 Mackenzie, Ann. d. Phys. u. Chem.. Leipzig, 1876, Bd. i. S. 438 ; Setsehenow, Ztschr. 
f. physikal. Chem., Leipzig, 1889, Bd.' iv. S. 117; Hiifner, Arch. f. Physiol., Leipzig, 
'1894, S. 130 ; 1895, S. 209. . 
8 Ann. d. Chem. a. Phann., Bd. xciii. S. 1 ; "Gasometrische Methoden," Braunsclnvcig, 
1857, S. 136. 
9 Ztschr. f. -physikal. Chem.. Leipzig, 1S92, lid. ix. S. 174. 
10 Ann. d. Phys. u. Chem., Leipzig. 1S76, Bd. i. S. 632; Arch. f. Physiol., Leipzig, 
1890, S. 27. 
