94 



ION SERIES AND PROTEINS, 



in equivalent proportions with egg albumin. The curve for H3PO4 is 

 the highest curve and if we compare the values for H3PO4 with those 

 ior HCl (or H2SO4) we notice that for each pH the ordinate for H3PO4 

 is as nearly three times as high as that for HCl as the accuracy of our 

 experiments permits. This means that under the conditions of our 

 experiments phosphoric acid combines with albumin in molecular 

 proportions and that the anion of albumin phosphate is the mono- 

 valent anion H2PO4. 



200 



180 



^ 140 



to 



CO 120 



^ 100 

 c^ 



"0 80 



e 



<S 60 



40 



20 





 pH 1 2 3 4 5 6 



Fig. 4. Osmotic pressure of different albumin-acid salts. The ordinates indi- 

 cate the osmotic pressure (in mm. of 1 per cent albumin solution) ; the abscissae 

 are the pH. All solutions are 1 per cent in regard to isoelectric albumin. The 

 curves for albumin chloride and albumin phosphate are identical. 



The values for oxalic acid are for pH above 3.2 not quite twice as 

 high as those for HCl, indicating that for these values of pH oxalic 

 acid combines to a greater extent in molecular and only to a smaller 

 extent in equivalent proportions with albumin. 



If egg albumin behaves like gelatin we should expect that the curves 

 of osmotic pressure for albumin phosphate and albumin chloride when 

 plotted as a function of the pH should be identical, since the anion is 

 in both cases monovalent; that the curve for albumin sulfate should 



