CARBONIC OXIDE IIEMOGIOBIN. 
239 
haemoglobin, and Podolinski ' 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 I he 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 Hemoglobin (CO-Hemoglobin). 
Mode of 'preparation. — A current of pure carbon monoxide is passed 
through a saturated solution of oxyhemoglobin. The solution acquires a 
carmine-like tint in contrast to the scarlet colour of oxyhemoglobin. This 
solution is then cooled to 0° C, and, after being treated with one-fourth of 
its volume of alcohol previously cooled to 0° C, is set aside at a tempera- 
ture which must not rise above 0° C, but which should be as low as possible. 
After some hours or days, the CO-compound, which is more sparingly soluble 
than Og-haemoglobin, separates in crystals, of which the forms are identical 
with those of that body. 
The absorption of light by CO-haemoglobin. — (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 oxyhemoglobin. 
Between D and E are seen two absorption-bands which, unless very 
closely studied, appear absolutely identical with those of oxyhemo- 
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-haemoglobin. — These 
constants were re-determined by Htifner in 1894, at the same time as 
those of oxy- and reduced lnemoglobin, and for the same spectral 
regions, with the results exhibited below. 2 The coefficients of extinction 
in the case of CO-hsenioglobin are designated for the region X 554-X 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 . 
A c 
A' c 
X 554-A 565 
X 531-5-A 542-5 
0-001383 
0-001263 
1 " Ueber die Austreibbarkeit des CO- und NO- aus dem Blute, 
Bonn, 1872, Bd. vi. S. 553-555. 
2 Hiifner, op. cit., S. 141 and 142. 
'Arch.f. d. gcs. Physiol. 
