CO-HEMOGLOBIN 



501 



reduced haemoglobin may preserve their colour and absorption-bands 

 indefinitely. Haldane and Lorrain Smith 1 state that carboxyhaamo- 

 globin may be recognised in dilutions of 1 : 1,000,000, if oxygen be 

 absent and the effect of CO on haemoglobin be thereby increased. 



A CO-haamoglobin compound analogous to methaemoglobin does 

 not exist. 2 



100i 



-05 -10 -15 -20 -25 -30 -35 '40 -45 -50 



Percentage of Carbonic Oxide 



CO-hsemochromogen 



Pregel 3 has shown that hasmochromogen binds O 2 more firmly 

 than CO, and in this it differs from hemoglobin. Acethaamatin prepared 

 by Schalfe Jeff's method 4 and recrystallised with quinine, according to 

 Kuster, 5 is reduced with hydrazinhydrate in a special apparatus which 

 prevents the access of air ; is saturated with CO, 6 and precipitated with 

 a saturated solution of sodium chloride, saturated with CO. 



CO-hasmochromogen resembles CO-hasmoglobin by being decomposed 

 with potassium ferricyanide. Each atom of Fe binds 1 atom of CO. 



CO-hasmochromogen contains for 1 Fe not 4 but 5 N, because of 



1 J. Haldane and J. Lorrain Smith, Journal of Physwl. 22. 253 (1897-98). 



2 H. Bertin-Sans and J. Moitessier, ibid. 113. 210 (according to Maly's Jahresber. 

 f. Tierchem. 22. 90), (1892). 



3 Fritz Pregel, Zeitschr. /. physiol. Ckem. 44. 173 (1905). 



4 Schalfejeff, Ber. d. deutsch. chem. Ges. 18. abstract 232 (1885), also Zeits.f. phys. 

 Ckem. 30. 390 (1900). 5 Kuster, Zeits. f. phys. Chem. 30. 391 (1900). 



6 Prepared from oxalic acid and concentrated H 2 S0 4 and preserved over caustic 

 potash solution. 



