THE MOLECULAR WEIGHT OF HEMOGLOBIN 



87 



freezing-point. If Adair's calculation may be relied upon the depres- 

 sion of the freezing-point would be of the order of 0-00001° C, a 

 quantity so small as to put the measurement outside the realm of 

 profitable research. 



But if the recognised methods for the indirect determination of 

 molecular weights have, with the exception of osmometry, failed, 

 there is some compensation in the knowledge that an entirely new 

 and very beautiful method has been born of the desire to know the 

 molecular weight of haemoglobin. Certainly chemistry owes much 



8 



10 



11 



pH 



Conditions. Concentration of Hb less than 4 % 

 Fig. 17. • = distilled water, x = solution of saline concentration greater than 0-01 M. 



to haemoglobin in that this substance only yields up its secrets to 

 those who arm themselves with novel and beautiful methods of 

 investigation. None could be more fascinating than the method 

 of determination of molecular weight by ultracentrifugalisation. This 

 technique is due to Professor Svedberg(8) of Upsala. I am told that 

 the information was won at a cost of "thousands of pounds" and I 

 can well believe it. 



The reader will be nearer to an understanding of Svedberg's work 

 if he considers the conditions prevailing in the atmosphere. Close 

 to the earth the air is densest, as an ascent is made the air becomes 

 increasingly more rare. These facts do not change with time. An 



