236 HEMOGLOBIN. 



chamber connected with the mercurial pump, some of the oxygen must be used 

 up in oxidising the readily oxidisable substances existing in the blood, and 

 especially in venous blood, and an error will be thereby introduced unequally 

 affecting different samples of blood, an error which is influenced by the 

 duration and extent to which the heat is applied to the blood and the rapidity 

 with which the aqueous vapour and gases evolved by the blood are removed. 



The photographic spectrum of reduced haemoglobin. When 

 the molecule of dissociable oxygen is removed from oxyhaemoglobin, 

 either by the action of reducing agents, or by boiling in vacuo, the 

 absorption-band in the extreme violet is remarkably displaced towards 

 the less refrangible end of the spectrum, the centre of absorption- 

 corresponding to X 426-0. The difference in the position of Soret's 

 band in the oxy- and in reduced haernoglobin is shown in the photo- 

 type (Fig. 33). VvHien we reflect that the addition of a molecule of 

 oxygen to the enormous molecule of haemoglobin cannot affect in an 

 appreciable manner the mass of the molecule, we must conclude that 

 the displacement of the absorption-band towards the ultra-violet end 

 when hemoglobin combines with oxygen (all other conditions remaining 

 the same), indicates that this combination leads to a notable acceleration 

 of the motion of the intramolecular group of carbon atoms upon which 

 the extreme violet absorption-band depends. 



The amount of oxygen with which haemoglobin combines to 

 form oxy haemoglobin. It is believed, on various grounds, that one 

 molecule of haemoglobin combines with one molecule of oxygen to form 

 the compound which we know as oxyhaemoglobin. 



The most recent determinations made by Hlifner have shown that 

 1 grm. of reduced haemoglobin of the ox can link to itself T338 c.c. of 

 oxygen or carbonic oxide (measured at C. and 760 mm. pressure). 

 The molecular weight of the haemoglobin of the ox (calculated from 

 Hiifner's most recent estimations of the iron which this body contains) 

 = 16669. The volume of oxygen absorbed by reduced haemoglobin, 

 calculated from this molecular weight, should be 1*34 c.c., so that the 

 result of experiment agrees in a surprising manner with theory. 



Differences in chemical reactions between solutions of reduced 

 and oxyhaemoglobin. 1. Solutions of reduced haemoglobin when boiled 

 in vacuo, or subjected to the action of CO, unlike solutions of oxyhaemo- 

 globin, yield no oxygen. 



2. They are not decomposed even by long contact with trypsin, which 

 readily splits up oxyhaemoglobin into hsematin and the products of 

 trypsin proteolysis. 



3. They are unaffected by H 2 S, which, when acting for a sufficient 

 length of time upon oxyhaemoglobin, converts it into sulpho-methaemo- 

 globin. 



4. Nitrites, potassium ferricyanide, and permanganate, and many 

 other oxidising and reducing agents, exert no action on reduced haemo- 

 globin, whilst they convert oxyhaemoglobin into methaemoglobin. 



5. When treated with alcoholic or watery solutions of acids or 

 alkalies, in the complete absence of free oxygen, haemoglobin yields 

 purple-red solutions or precipitates. The haemoglobin is, under these 

 circumstances, split up into an iron-containing coloured body Jicemo- 

 chromogen and into an albuminous body or bodies. Oxyhaemoglobin, 

 under the same conditions, splits up into an iron-containing body 

 Ticematin and albuminous products. 



