SALT EFFECTS OF PHOSPHATES 



175 



is far from constant and increases with increasing concentration 

 of the salt, but averages about 2.65 X 10~ 8 . 



In order to better appreciate this relation the points were 

 plotted on coordinate paper, using values of H as abscissae and 

 corresponding values of (1 — a)/ a as ordinates (fig. 2). Then 



1.5 ZjO 25 



HYDROGEN ION CONCENTRATION */0 ? 

 Fig. 2 



the smooth curves A, B, and C, were drawn through the points 

 which represented the same concentration of salt in the solution. 

 These curves were then treated as follows: for values of (1 — a) /a 

 equal to 4, 5, 6, 7, 8, 9, 10 and 11 the change in hydrogen ion con- 

 centration for changes in concentration of salt from 0.5 N to 

 0.25 N and from 0.25 N to 0.166 N, were measured on the curves. 



