CHAP. II.] 



THE BLOOD. 



119 



before sealing whether the froth which fills the division F exhibits, as it 

 ought to do, the spectrum of reduced haemoglobin; if it does so, 'after 



FIG. 25. APPARATUS FOB THE PREPARATION OF HAEMOCHROMOGEN. 



sealing, the fluids contained in the bulbs D and F are mixed by reversing 

 and shaking their contents together. 



If in this way, in the complete absence of oxygen, acid alcohol 

 has been mixed with a little haemoglobin, a precipitate forms, which 

 soon loses its colour on being heated in the water bath, whilst the 

 liquid becomes coloured purple. The liquid then exhibits four absorption 

 bands, of which two are situated between C and D. A third absorption 

 band of greater degree of sharpness and darkness extends between D and E, 

 and a fourth is situated between b and F. The absorption band nearest C 

 is, if the oxygen has been thoroughly expelled, exceedingly weak and may 

 be due to a trace of haematin, as its position is identical with the band of 

 acid haematin. 



If instead of sulphuric acid, alcohol holding caustic alkali in solution has 

 been employed, on mixing the fluids we obtain a rose-red or purple- 

 red precipitate and a solution having the same tints. This exhibits two 

 absorption bands which are identical . with those of Stokes' alkaline 

 haematin. 



II. Lately Hoppe-Seyler has recommended the following method 1 . 



A solution of oxy-haemoglobin is placed in a glass tube, and then a 

 smaller glass tube containing solution of dilute phosphoric or tartaric acid, 

 or solution of potassium hydrate, is introduced into the larger tube, the open 

 end of which is then drawn out and sealed ; the large tube with its 

 contained smaller tube is then heated gently for some time, care being 

 taken that the contents of the two tubes do not mix. The oxy-haemoglobin 



1 Hoppe-Seyler, "Weitere Mittheilungen tiber die Eigenschaften des Blutfarb- 

 stoffs." Zeitschrift f. phys. Chem. Vol. i. p. 138. 



