ACTION OF REAGENTS ON OXYH^EMOGLOBIN. 207 



position of ox y hemoglobin with a rapidity which depends upon their 

 concentration. 



Oxyhaemoglobin is soluble in highly diluted alcohol, the solutions 

 resisting putrefaction much longer than aqueous solutions. By contact 

 with even highly dilute alcohol, crystals of oxyhsemoglobin become much 

 more sparingly soluble in water. Oxyhaemoglobin is insoluble in absolute 

 alcohol. When crystallised oxyhaenioglobin is treated with a large excess 

 of absolute alcohol, it is under favourable circumstances converted into an 

 insoluble crystalline modification, to which Nencki and Sieber have 

 given the name of parahcemoglobin. 1 This body cannot be looked upon 

 as a chemical individual. Oxyhaemoglobin is insoluble in chloroform, 

 benzol, and carbon disulphide. 



4. Diffusibility. Oxy haemoglobin offers a remarkable example of a 

 soluble crystalline body, which, judged by its power to pass through a 

 septum of parchment paper, must be declared to be absolutely non- 

 diffusible. This character depends upon the enormous size of its 

 molecule. 



Comparison of the action of certain reagents on solutions of 

 oxyheemoglobin and on solutions of albuminous bodies. It has 

 already been incidentally stated that in haemoglobin an iron-containing 

 body is linked to an albuminous body or bodies, and reference has been 

 made to the fact that, under the action of various agents, oxyhaemoglobin 

 breaks up into the iron-containing hsematin, and into albuminous bodies. 

 Although the decomposition of haemoglobin and its products will be con- 

 sidered in some detail in a future section, it is convenient in this place 

 to refer to this point, and to state that when oxyhaemoglobin is decom- 

 posed so as to yield hsematin and albuminous substances, the former 

 amounts approximately to 4 per cent, and the latter to 96 per cent, of 

 the original hemoglobin. 



Such being the case, it is of particular interest to contrast the 

 action of certain reagents on solutions of albuminous bodies, and on 

 solutions of oxyhaemoglobin. 



Solutions of oxyhaemoglobin differ remarkably from solutions of 

 albuminous bodies in their behaviour towards a large number of 

 reagents. 



As Klilme pointed out long ago, 2 all those tests for albumin which 

 do not immediately bring about a decomposition of oxyhaemoglobin, 

 furnish a negative result when applied to aqueous solutions of this 

 body. Cupric and ferrous sulphates, mercuric chloride, silver nitrate, 

 neutral and basic acetates of lead, all of which precipitate albuminous 

 solutions, occasion (so long as the body remains undecomposed) no pre- 

 cipitate not even cloudiness when added to solution of oxyhaemo- 

 globin. So soon, however, as the red colour of oxyhaemoglobin has 

 disappeared under the action of any one of the above salts, and the 

 brown colour due to haematin has appeared (a result which they all 

 sooner or later bring about), the characteristic albuminous precipitates 

 appear. 



1 M. Nencki und N. Sieber, " Untersuch. ueber die Blutfarbstoff, " Ber. d. deutsch. 

 chem. Gesdhcli., Berlin, 1885, Bd. xviii. S. 392 ; M. Nencki und B. Lachowitz, "Ueber das 

 Parahiimoglobin," Hid., Bd. xviii. S. 2126. The reader is referred for a criticism of Nencki 

 and Sieber's researches on parahtemoglobin, to a paper by Hoppe-Seyler, entitled "Ueber 

 Blutfarbstoffe und ibre Zersetzungsproducte, " Ztschr. f, physiol. Chem., Strassburg, 1886, 

 Bd. x. S. 531. 



2 "Lehrbuch der physiolog. Chemie," Leipzig, 1866, S. 207. 



