130 HEMOGLOBIN 



concentration as blood, say, 15 per cent., Adair finds an apparent 

 osmotic pressure corresponding to a value for n of about 2-5. His 

 view is, however, not that the haemoglobin becomes less aggregated as 

 it becomes more concentrated, but that the molecules are so close 

 together as to interfere with one another's freedom, and also with one 

 another's power of receiving their rightful number of oxygen impacts. 

 Thus, starting with the assumption that the fundamental equation is 



Hb4+402 = Hb408, 



a correction has to be introduced in order to express the degree to 

 which each molecule screens its fellow from oxygen. The lines along 

 which Adair argues are those which have already been appHed to 

 sugar solutions. It is known that whereas a dilute sugar solution 

 obeys the law 



PV = ET, 



where P is the osmotic pressure, F is the volume in Utres of solution 

 per gram molecule, R is the gas constant and T the absolute tempera- 

 ture, a strong solution behaves as though it had a lower pressure 

 than the number of molecules would indicate, and a correction b has 

 to be subtracted from the volume so that the form of the equation 

 for a strong solution of hasmoglobin would be 



P{V-b) = RT. 



For haemoglobin 6=162Htres, according to Adair, and V is the 

 volume in Utres which contains 67,000 grams of haemoglobin. 



Take for instance a 14 per cent, solution of haemoglobin; 67,000 

 grams of haemoglobin would occupy 480 litres. So the equation would 

 stand 



P (480 - 162) = RT. 



P, therefore, would be higher than might be expected, that is to say, 

 the solution would behave as though more molecules were present, 

 i.e. as though the haemoglobin were in a less state of aggregation. 



It is interesting to apply this conception as Adair did to Hill's 

 equation, for Hill was very clear that n in his equation did not 

 mean the actual state of aggregation, but such state of aggregation 

 as might be deduced from the osmotic pressure. Therefore, in this 

 case, n would equal not 4, but something under 3, and that value 

 would give a curve which, when corrected for hydrogen-ion con- 

 centration, would be very near to that actually found for blood. 



