HAEMOCHROMOGEN. 255 
to the relations of lia-mochroinogen to haemoglobin, and the pari which 
it plays in relation to the optical properties of , and the chemical affinities 
for Liases manifested by, the complex molecule of haemoglobin. 
Methods of preparing solutions containing hcemochromogen oy the direct 
decomposition of hcemoglobin. — Without referring to a more complicated 
and in some respects more satisfactory method of decomposing haemo- 
globin in the absence of oxygen, 1 the following very simple method, 
which, like the first, we owe to Hoppe-Seyler, 2 will be described. 
A solution of oxyhemoglobin is placed in a glass tube, and then a 
smaller glass tube containing a solution of sodium or potassium hydrate, 
or, if desired, of tartaric or phosphoric acid, is introduced into the larger 
tube, the open end of which is then drawn out and sealed in the blow- 
pipe flame. The apparatus thus prepared is then subjected to gentle 
heat, taking care not to incline the tubes so as to cause their contents 
to mix. 
The oxyhemoglobin contained in the larger, outer tube first becomes 
reduced, and thereafter the oxygen contained in the air of the tube is 
absorbed by the haemoglobin. When many days have elapsed, and the 
whole of the haemoglobin is again reduced, the tubes are inverted and 
their contents mixed, when the formation of haemochromogen may be 
followed by the changes in colour and in the spectrum, which the 
colouring matter undergoes. 
Physical and chemical properties. — When acted upon by dilute solu- 
tions of the caustic alkalies, haemochromogen gives rise to a beautiful 
cherry-red solution, which, when sufficiently diluted, exhibits two 
absorption-bands apparently identical with those of Stokes' reduced 
lia-matin, which have already been referred to. 
The visible spectrum of solutions of haemochromogen in alkaline 
solutions is distinguished from all others by the extraordinary intensity 
and sharpness of the absorption-band nearest to D. The second ab- 
sorption-band, which is very much less intense, has less sharply-defined 
borders. The solution, even when concentrated, absorbs very little of 
the red. 
The following are measurements of the position of the absorption- 
bands in the visible spectrum by Hoppe-Seyler and myself: — 
Gamgee's measurements 3 (1878) X 567-547 X 532-518 
Hoppe-Seyler's „ i (1889) X 565-547 A 527-514 
My study of the photographic spectrum of haemochromogen has led 
to the following results : 5 — Solutions, even of very great dilution, exhibit 
an absorption-band between h and g. This band has the same position 
as the band of CO-haemoglobin, but is much more intense. With one 
part of haemochromogen in 25,000 parts of water, a stratum 10 mm. thick 
being examined, an intense absorption-band occupies the region between 
X410 - and /,430 - 0. From the examination of solutions of various strengths 
it results that the mean ray absorbed corresponds to about X 420 - 0. 
By heating to 110° C. a solution of haemochromogen mixed with 
a sufficiently concentrated solution of sodium hydrate, haemochromogen 
1 Hoppe-Seyler, Med.-chem. Untersuch., Berlin, S. 540 and 541 ; and Gamgee's 
"Physiological Chemistry."' vol. i. pp. 118 and 119. 
2 "Physiol. Chem., ; ' 1878, S. 390. 
3 "Physiological Chemistry,'" 1SS0, vol. i. p. 111. 
4 Ztschr.f. physiol. C'hem., Strassburg, 1889, Bd. xiii. S. 496. 
5 Gamgee, Proc. Roy. Soc. London, 1896, vol. lix. p. 276. 
