6o 



DECOMPOSITION OF HEMOGLOBIN. 



all of the oxygen must first be removed from the blood and the apparatus, possibly 

 through the passage of hydrogen, in the preparation of nitric-oxid hemoglobin. 

 For this reason it cannot be formed within the body. Nitric-oxid hemoglobin is 

 a still more active chemical combination than carbon-monoxid hemoglobin. It 

 is of a bluish-violet color and in the spectrum it exhibits two absorption-bands, 

 pretty much like those of the two other gas-combinations, but less intense, and 

 not dissolved by reducing substances. 



The three combinations of hemoglobin with oxygen, carbon monoxid 

 and nitric oxid just considered crystallize like gas-free hemoglobin. 

 They are isomorphous and their solutions are not dichroic. All three 

 gases unite in equal amounts with hemoglobin and they can be ex- 

 pelled in a vacuum. 



Hydrocyanic acid also forms readily decomposed combinations with hemo- 

 globin. These develop in cases of hydrocyanic-acid poisoning, and they exhibit 

 two bands that are situated somewhat nearer the violet than those of oxyhemo- 

 globin and are slowly obliterated by reducing substances. This hydrocyanic-acid 

 hemoglobin appears to consist of hydrocyanic acid plus oxyhemoglobin. There 

 is, besides, a further combination of hydrocyanic acid with oxygen-free hemo- 

 globin. 



DECOMPOSITION OF HEMOGLOBIN. 



Hemoglobin can be decomposed into: (i) iron-containing, pig- 

 mented hematin and (2) albuminoid, colorless globin, containing sul- 

 phur: (a) by addition of all acids, even feeble carbon dioxid in the 

 presence of much water; (b) by strong alkalies; (c) by all agents that 

 coagulate albumin, as well as by heat at a temperature of from 70 to 

 80 C. ; (d) by ozone. 



Hematin. C 32 H 32 N 4 FeO 4 represents about 4 per cent, of the hemo- 

 globin in the dog. It is of blackish-blue color in reflected light, brown 

 in transmitted light, insoluble in water, alcohol and ether, but soluble 

 in dilute alkalies and acids, as well as in alcohol containing sulphuric 

 acid or ammonia. It does not occur within the body. Hematin thus 

 developed appears in an amorphous form, although it has also been 

 possible to produce it crystallized in needles and rhombic plates. 



i. 



2. 



700 650 600 



BO D 



550 



500 



Eb F 



450 



FIG. 16. The Absorption-spectra of Hematoporphyrin, with the Fraunhofer Lines and a Scale Whose Figures 

 Indicate the Wave-lines of Light in Millionths of a Millimeter. 



In the decomposition of hemoglobin containing oxygen hematin at once 

 results, oxygen being bound. On the other hand, oxygen-free hemoglobin yields 

 in a similar process of decomposition, at first a forerunner of hematin deficient 

 in oxygen, namely purple-red hemochromogen (C 34 H 36 NFe 4 O 5 ) . This, however, 

 is transformed into hematin in the presence of oxygen by taking up the latter. 

 Hematin therefore represents an oxidization-stage of hemochromogen. The latter 



