CARBONIC OXIDE HEMOGLOBIN. 



239 



haemoglobin, and Podolinski 1 succeeded in dissociating blood saturated 

 with nitric oxide, by passing a stream of hydrogen through it for an 

 hour and a half; at the end of which time the blood presented the 

 absorption-band of reduced haemoglobin. 



Having passed in review the chief facts which exhibit the relation- 

 ship existing between the different compounds of haemoglobin, and which 

 illustrate the nature of the combination of haemoglobin with gases, some 

 of the characters and properties of CO-haemoglobin and NO -haemoglobin, 

 but particularly of the former, must be systematically though briefly 

 described. 



CARBONIC OXIDE HAEMOGLOBIN (CO-HAEMOGLOBIN). 



Mode of preparation. A current of pure carbon monoxide is passed 

 through a saturated solution of oxyhsemoglobin. The solution acquires a 

 carmine-like tint in contrast to the scarlet colour of oxyhsemoglobin. This 

 solution is then cooled to C., and, after being treated with one-fourth of 

 its volume of alcohol previously cooled to C., is set aside at a tempera- 

 ture which must not rise above C., but which should be as low as possible. 

 After some hours or days, the CO-compound, which is more sparingly soluble 

 than Og-hsemoglobin, separates in crystals, of which the forms are identical 

 with those of that body. 



The absorption of light by CO-hsemoglobin. (a) The visible 

 spectrum. Solutions of this body possess more of a bluish-red tint 

 than the 2 -compound. If solutions of equal concentration of the 

 oxygen and carbonic-oxide compounds be compared, it will be found, on 

 spectroscopic examination, that the CO-compound absorbs the blue rays 

 of the spectrum to a less degree than oxyhaemoglobin. 



Between D and E are seen two absorption-bands which, unless very 

 closely studied, appear absolutely identical with those of oxyhaemo- 

 globin (see Plate I., Spectrum 6). On careful measurement, however, it 

 is seen that both the bands are very slightly shifted in the direction 

 of E; that is to say, towards the violet end. This is best seen by 

 noticing the interval between D and the adjacent border of the first 

 absorption-band ; in the case of the CO-compound this interval is broader 

 than in that of the 2 -compound. 



The spectrophotometric constants of CO-hsemoglobin. These 

 constants were re-determined by Hiifner in 1894, at the same time as 

 those of oxy- and reduced haemoglobin, and for the same spectral 

 regions, with the results exhibited below. 2 The coefficients of extinction 

 in the case of CO -haemoglobin are designated for the region X 554-?, 565, 

 e c , and for the region x 531 - 5 X 542'5 e' c , whilst the corresponding 

 absorptive relations are designated A c and A' c . 



1 " Ueber die Austreibbarkeit des CO- und NO- aus dem Blute," Arch.f. d. ges. Physiol., 

 Bonn, 1872, Bd. vi. S. 553-555. 



2 Hiifner, op. cit., S. 141 and 142. 



