2 4 o HEMOGLOBIN. 



(b) The photographic spectrum of CO-heemoglobin. In Fig. 35 

 are shown reproductions of the photographic spectrum of this com- 

 pound, contrasted with that of the oxygen compound. The band of 

 Soret is just as well marked in the one as in the other, but in the 

 case of the CO-hsemoglobin there is a decided shifting of the band 

 in the extreme violet towards the red, which is somewhat curious, 

 considering that the bands in the visible spectrum are, though to a 

 much less extent, shifted in the opposite direction. I have shown that 

 there is absolute identity in the position of the absorption-band in the 

 extreme violet, in the case of the CO- and NO- compounds of haemoglobin. 1 



The principal characteristic reactions of CO-hsemoglobin. 

 1. When treated with Stokes' reagent, solutions of ammonium sulphide, 

 and the like, no change whatever occurs, either in the colour or the 

 spectrum of blood saturated with carbonic oxide, or in solutions of 

 pure CO-hsemoglobm. 



G HK L M N 



FIG. 35. The photographic spectrum of oxyhsemoglobin and of CO-hsemoglobin. 



2. The blood of men or animals asphyxiated by carbonic oxide, or 

 by a gas containing it (charcoal fumes, coal gas), if pretty fully saturated, 

 possesses and retains for a long time a florid arterial colour, and when 

 diluted is found to be partially or completely irreducible. Hoppe- 

 Seyler found that if such blood is sealed in glass tubes, it may retain for 

 some years its characteristic spectroscopic properties, and even admit 

 of CO being boiled out, with the aid of the mercurial pump, and 

 identified by chemical analysis. 



3. The addition of a concentrated solution of sodium hydrate (density 

 1*3) to blood, saturated with CO in the proportion of about two parts 

 of the former to one of the latter, causes the blood to assume a fine 

 scarlet colour, and to deposit a cinnabar-red precipitate. The same 

 coloration and precipitate is produced with solutions of pure CO- 

 hsemoglobin. According to Hoppe-Seyler, the precipitate is composed 

 of CO-hsemoglobin, rapidly passing into CO-hoemochromogen. When 

 normal blood is treated in the same way with sodium hydrate, it is 



1 Gamgee, Proc. Roy. Soc. London, 1896, vol. lix. p. 276. 



