THE COLLOID-CHEMISTRY OF SOAPS 



143 



4 



In order to test further the general truth of the relationship 

 between hydration capacity and foaming qualities of the different 

 soaps, we next studied the potassium soaps of the acetic acid 

 series. As previously described, 1 the potassium soaps are more 

 soluble in water and have a higher solubility for water than the 

 corresponding sodium soaps. It was in consequence to be expected 

 at a given concentration (a) that the potassium soaps would not 

 begin foaming as early as the corresponding sodium soaps, (b) that 

 this foaming quality would be lost earlier with increase in temper- 



FiauraSO. 



ature and (c) that the soaps of the higher fatty adds would 



distinct foaming qualities at temperatures at which the corresponding 



>n soaps would be so " insoluble " or yield such solid systems 



with water as to make foaming impossible. The truth of 



1 See pages 14 and 23. 



