PRODUCTS OF DECOMPOSITION. 243 



amount of either of these gases which is absorbed is independent of the 

 other. 



A careful study of the whole of Bohr's researches on this subject, as well 

 as those on the various hypothetical compounds of haemoglobin with oxygen, 

 has convinced me that his work is pervaded by fallacies, which spring in part 

 from erroneous methods of work, in part from a non-appreciation of physical 

 principles of which the exactitude is beyond dispute ; the discussion of Bohr's 

 statements in a text-book would be, under these circumstances, altogether out 

 of the question. 



THE IMMEDIATE DERIVATIVES AND PRODUCTS OF DECOM- 

 POSITION OF OXYH^MOGLOBIN AND REDUCED HAEMO- 

 GLOBIN. 



Introductory observations. It has already been stated, that when 

 the blood-colouring matter is subjected to the action of strong alkalies 

 and of acids, or even of salts possessing an acid reaction, or to the 

 action of heat, of alcohol, and of many other chemical agents, it under- 

 goes a decomposition of which the chief products are an albuminous 

 substance or substances, and a colouring matter which contains the whole 

 of the iron originally present in the oxyhsemoglobin or haemoglobin 

 decomposed. 



Under ordinary circumstances, when oxyheeinoglobin is decomposed in 

 the presence of air, the coloured product of decomposition is the body 

 we know as licematin, the amount of which produced corresponds theo- 

 retically to 3*8 per cent, of the oxyhsemoglobin. Traces of organic 

 acids are said to result from the decomposition, the main product of 

 which is, however, composed of the albuminous residue of the blood- 

 colouring matter (vide infra). If, however, instead of decomposing 

 oxyhciemoglobin, we employ reduced haemoglobin and carry out the 

 process in the complete absence of oxygen, we obtain, not hsematin, but 

 a body of which some of the optical characters were first described 

 by Stokes, and which he named reduced hcematin, to indicate that it 

 may be obtained by the action of reducing agents on hseinatm. Instead 

 of employing this term, it is better to adopt that of hamiochromogen, 

 introduced by Hoppe-Seyler, to whom we owe nearly all the knowledge 

 we possess with regard to it. According to Hoppe-Seyler, hsemochro- 

 mogen constitutes the coloured radicle of the blood-colouring matter, 

 upon which its essential optical properties and its property of com- 

 bining with oxygen, carbonic oxide, and nitric oxide depend. 



Under the influence of carbonic acid, and very dilute acids acting 

 for comparatively short periods of time, oxyhsemoglobin, long before the 

 complete splitting up into hsematin, undergoes a change which is doubt- 

 less of the nature of a decomposition ; this change is identical with that 

 which is also brought about by a variety of oxidising agents, typically 

 by ozone, nitrites, and potassium ferricyanide ; to the body which 

 results, the name of methsemoglobin has been given. It will be con- 

 sidered first amongst the decomposition products of oxyhsemoglobin. 

 We shall show it to be a substance which is formed in the living body, 

 under the influence of certain poisonous agents, and is occasionally 

 found in old blood extravasations; it possesses the power of forming 

 molecular compounds with certain bodies, such as nitrites, hydrocyanic 

 acid, and cyanogen. 



