PRODUCTS OF DECOMPOSITION. 243 
amount of either of these gases which is absorbed is independent of the 
other. L 
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 
n^Z l S N 0F OXYHEMOGLOBIN AND REDUCED H.EMO- 
Introductory observations.— It has already been stated, that when 
the blood-colouring matter is subjected to the action of strong alkalies 
and oi acids, or even of salts possessing an acid reaction, or to the 
action oi 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 
oi the iron originally present in the oxyhemoglobin or hemoglobin 
decomposed. ° 
Under ordinary circumstances, when oxyhemoglobin is decomposed in 
the presence of air, the coloured product of decomposition is the body 
we know as hcemahn, the amount of which produced corresponds theo- 
retically to 3-8 per cent, of the oxyhemoglobin. 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 
oxyhemoglobin, we employ reduced hemoglobin and carry out the 
process m the complete absence of oxygen, we obtain, not hematin, 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 hematin. Instead 
or employing this term, it is better to adopt that of hemochromogen 
introduced by Hoppe-Seyler, to whom we owe nearly all the knowledge 
we possess with regard to it. According to Hoppe-Seyler hemochro- 
mogen constitutes the coloured radicle of the blood-colouring matter 
upon winch 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 
tor comparatively short periods of time, oxyhemoglobin, long before the 
complete splitting up into hematin, undergoes a change which is doubt- 
less ol 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 methemoglobin has been given. It wiU be con- 
sidered first amongst the decomposition products of oxyhemoglobin 
We shall show it to be a substance which is formed in the li vino body 
under the influence of certain poisonous agents, and is occasionally 
round in old blood extravasations ; it possesses the power of formino- 
molecular compounds with certain bodies, such as nitrites, hydrocyanic 
acid, and cyanogen. 
