112 PRODUCTS OF THE DECOMPOSITION OF HAEMOGLOBIN. [BOOK I. 



Seyler's re- More recently Hoppe-Seyler has published fresh re- 



searches and searches on the subject 1 . He opposes vehemently the view 

 views on that methaemoglobin is to be looked upon as a peroxidized 



methaemo- oxy -haemoglobin, resting his opposition very much on the 



globin. facts (a) that when a solution of oxy-haemoglobin is intro- 



duced into the vacuum of the mercurial pump, so as to remove a part of its 

 respiratory oxygen, and then is left at the temperature of the room, the 

 fluid is found to contain a mixture of methaemoglobin and reduced 

 haemoglobin, (b) that when a piece of palladium saturated with hydrogen 

 is introduced into a flask filled with a saturated solution of oxy-haemo- 

 globin, the whole of the colouring matter is very quickly converted into 

 methaemoglobin, unless the quantity of the oxy-haemoglobin present was very 

 large. In these two experiments conditions existed for removing a great 

 part at least of the oxygen of the oxy-haemoglobin, and how therefore could 

 a per-oxy-haemoglobin be formed 1 



Hoppe-Seyler has himself added lately the strongest proof of the possibi- 

 lity of reconverting methaemoglobin into oxy-haemoglobin by shewing that 

 when a solution of methaemoglobin is allowed to decompose in sealed glass 

 tubes, the band in the red of that body disappears and the spectrum of 

 reduced haemoglobin appears. When some months have elapsed and 

 the change has been completed, the tube is cooled to until ice begins 

 to form, then opened, and alcohol is added to the extent of ^ of the volume 

 of the solution; on afterwards lowering the temperature to - 7 0. or 10C. 

 crystals of oxy-haemoglobin separate, 



It is now admitted by Hoppe-Seyler that this possibility of reconver- 

 sion into haemoglobin distinguishes methaemoglobin from haematin. Ac- 

 cording to this author methaemoglobin contains more oxygen than haemo- 

 globin but less than oxy-haemoglobin, and this oxygen is in a more stable 

 combination than in the latter body. 



The Proteid matter derived from the decomposition of Haemoglobin. 



When a solution of haemoglobin is boiled, the liquid becomes in- 

 tensely turbid and a coagulum soon separates which possesses a dirty 

 reddish-brown colour. Under the influence of heat the haemoglobin, 

 has been decomposed, and has yielded two substances insoluble in water, 

 the first of which is a proteid, and the second is the body already re- 

 ferred to as haematin. 



The same decomposition takes place when strong acids, or when 

 large quantities of alcohol, act upon haemoglobin, though the rate 

 at which it proceeds varies in these different cases. 



Very little information is possessed concerning the proteid matter 

 which results from this decomposition. According to Hoppe-Seyler it 

 behaves as a normal proteid in reference to bases and acids, .yielding 

 alkali- and acid-albumins. 



Preyer has described the proteid substance under the term of 

 Globin, as a body which is free from all inorganic matter, which is 

 insoluble in water, which swells in solutions of sodium chloride 



1 Hoppe-Seyler, "Die Zusammensetzung des Methamoglobin und seine Umwandlung 

 zu Oxyhamoglobin." Zeitschriftf. physiolog. Chemie, Vol. u. (1878) p. 150. 



