498 CHEMISTRY OF THE PROTEIDS CHAP. 



CO of '005 per cent of an atmosphere, or 0'035 mm. of Hg, a dilute 

 haemoglobin solution became 98 per cent saturated with CO, in the 

 absence of oxygen. See further p. 500. 



Haldane also showed that the relative saturating powers of carbonic 

 oxide and oxygen are not altered by an increase of the temperature 

 or increased saturation, while the absolute saturating power of both 

 carbonic oxide and of oxygen are diminished by a rise of temperature. 



The most characteristic property of the CO-hsemoglobin is its great 

 firmness, as the CO is only given off with great difficulty to the blood- 

 pump. Hiifner and his pupils 1 have repeatedly made use of this 

 property for estimating the volume of the gas united to haemoglobin, 

 and Burner's final estimate of the molecular weight of haemoglobin has 

 been based on CO-haemoglobin. 



The great firmness of the CO-hsemoglobin is the reason why feeble 

 concentrations of CO are able to displace the oxygen of the hsemo- 

 globin and why carbonic oxide is so poisonous. This gas, by uniting 

 with the haemoglobin, thereby prevents the taking in of oxygen. 

 Bock, 2 Hiifner, 3 and also Haldane have investigated the avidities of 

 oxygen and carbon monoxide for hemoglobin, one of the most interest- 

 ing examples of chemical equilibrium. Haldane 4 has shown that 

 symptoms of CO-poisoning do not manifest themselves, as long as the 

 body is at rest, till the CO, in otherwise normal air, amounts to about 

 05 per cent, while urgent symptoms are produced with amounts of 

 0'2 per cent of CO. In fatal cases of CO-poisoning, 5 the blood is 

 usually about 80 per cent saturated with CO. In recovery from CO- 

 poisoning the CO is driven off, fairly rapidly, through the lungs none 

 of it is oxidised. The supposed oxidation of carbonic oxide in the 

 living body has been discussed by Haldane. 6 



Identification by the spectroscope is not easy, as the absorption- 

 bands closely resemble those of oxyhsemoglobin, but two methods allow 

 of its ready recognition, namely : firstly, the addition of ammonium sul- 

 phide or Stokes' reagent, which produces no change, while in the case 

 of oxyhaemoglobin they convert the latter into reduced haemoglobin 



1 John Marshall, Zeitschr. f. physiol. Chem. 7. 81 (1882) : R. Kiilz, ibid. 7. 384 

 (1883) ; G. Hiifner, Arch. f. (Anat. u.) Physiol. 1894, p. 130. 



2 Joh. Bock, Zentralbl. f. Physiol. 8. 385 (1894). 



3 G. Hiifner, Arch. f. (Anat. u.} Physiol. 1895, p. 213; Arch. f. experim. 

 Path. u. Pharm. 48. 87 (1902). 



4 J. Haldane, Journ. of Physiol. 18. 430 (1895) ; see also the older papers by G. 

 Hiifner, Arch. f. (Anat. u.} Physiol. 1895, p. 213 ; H. Dreser, Schmiedeberg'' 's Arch. f. 

 experim. Path. u. Pharm. 29. 110 (1891) ; F. Hoppe-Seyler, Zentralbl. /. d. med. 



Wissensch. 1865, p. 52; Zeitschr. f. physiol. Chem. 1. 121 (1877). 



5 J. Haldane, Journ. of Physiol. 18. 430 (1895). 



6 J. Haldane, ibid. 25. 225 (1899-1900). 



