SOAPS AND PROTEINS 



sodium margarate, 24 liters; of sodium 

 stearate, 27 liters and of sodium arachi- 

 date, the enormous value of 37 liters. 

 These facts are illustrated in the remain- 

 ing bottles of Fig. 8 and, in graphic 

 form, in Fig. 9. 



Sodium margarate, holding its 24 

 liters of water to the mol of soap, assumes 

 its rightful place in the acetic series as 

 indicated in the broken line column of 

 Fig. 9, but, since it does not seem to be 

 settled as yet that margaric acid is 

 more than a " eutectic " mixture of 

 palmitic and stearic acids, this point 

 should not be too heavily stressed. The 

 soap of pelargonic acid (Cg) we have 

 not yet been able to study. Both the 

 sodium and potassium salts of cerotic 

 acid (27) are so slightly hydratable 

 S (even after subjection to high tempera- 

 | tures and increased atmospheric pressure) 

 2 that this acid does not fit into the smooth 

 series of the soaps already described. 

 Excepting these three acids, it will be 

 noted therefore that all the water-holding 

 soaps are of acids with an even number 

 of carbon atoms in the empiric formula, 

 a fact which may not be without signifi- 

 cance in deciding which of the acids of 

 the empiric formula CnH^n+iCOOH be- 

 long in a true series. 



In the experiment just described, 

 the water-holding power per gram-mole- 

 cule of soap was determined. In order 

 to get this value for equivalent weights 

 of the different soaps, the series of 

 experiments illustrated in Fig. 10 was 

 performed. In this instance, water was 

 added to one gram of each of the care- 

 fully dried sodium soaps until, after 



