30 SOAPS AND PROTEINS 



III 

 THE SYSTEM SOAP ALCOHOL 



1. Introduction 



It is the purpose of this section to take up the matter of the 

 production of various lyophilic colloid soap systems from materials 

 in which water is practically or entirely absent. The facts learned 

 under this heading will then serve, with the experiments described 

 earlier 1 on soap/ water systems, for a general theory of the lyophilic 

 colloid state. 2 



Of the many different " solvents " which will in this fashion 

 yield beautiful lyophilic colloid systems with various soaps, we 

 shall first take up the various alcohols, for not only do alcohols 

 (like glycerin) frequently appear in the processes of soap manu- 

 facture, but this or some other alcohol is commonly added to 

 soaps from without to make them " transparent." 



2. Experiments with Monatomic Alcohols 



a. Monatomic Alcohols of the General Composition CnHzn+iOH. 



1. A first set of experiments consisted in the determination of 

 the gelation capacities of various sodium soaps of the fatty acids of 

 the acetic series in the presence of absolute ethyl alcohol. For this 

 purpose we proceeded as in the experiments on the gelation 

 capacities of these soaps when water was the " solvent." The 

 soaps were made by adding to unit molar weights of the various 

 fatty acids the necessary chemical equivalents of half normal 

 sodium hydroxid in absolute alcohol. The mixtures were kept 

 in a water bath set at 75 C., and enough absolute ethyl alcohol 

 was then added to each until on cooling the soap-alcohol mixture 

 to 18 C. a " dry " gel was no longer obtained. In other words, 

 if the soap/alcohol system remained liquid or showed " syneresis " 

 it was held that its gelation limit had been exceeded. The results 



1 See page 9; also MARTIN H. FISCHER and MARIAN O. HOOKER: 

 Chem. Engineer, 27, 155 (1919). 



2 See page 64; also MARTIN H. FISCHER and MARIAN O. HOOKER: 

 Science, 48, 143 (1918); Chem. Engineer, 27, 188 (1919). 



