THE COLLOID-CHEMISTRY OF SOAPS 77 



the forces which appear in or are operative in solutions of the 

 most varied kinds. This is emphasized because there has been 

 much written, for example, regarding the all-important effects 

 of the electrical charges in determining the stability of colloids 

 in general and of the lyophilic colloids in particular. We do 

 not wish to deny the importance of this factor in some colloid 

 systems or under certain conditions, but it is too narrow a view 

 to take of what constitutes the lyophilic colloids in general. While 

 the play of electrical forces may be apparent in systems composed 

 of soaps and water, in those of proteins and water, etc., lyophilic 

 colloid systems may be built up, as illustrated in the preced- 

 ing pages, of materials in which the electrical factors are either 

 negligible or absent entirely. It will prove somewhat difficult, 

 to say the least, to conjure up orthodox electrical notions in 

 systems containing nothing but soaps with anhydrous alcohol, 

 toluene, benzene, chloroform or ether. 



VII 

 ON THE REACTION OF SOAPS TO INDICATORS 



In order to get ground materials of strictly reproducible type 

 for the observations on soaps detailed in the preceding pages, 

 we followed the expedient of producing " neutral " soaps by 

 simply adding to each other the necessary gram equivalents of 

 highly purified fatty acids and carefully standardized solutions 

 of alkali. We found that this method yielded more satisfactory 

 results than that of others who tried to obtain " neutral." " slightly 

 alkaline " or " slightly acid " soaps by adding to each other fatty 

 acid and standard alkali until some chosen indicator was pre- 

 sumed to show the mixture unit ral. alkaline or acid. As the next, 

 paragraphs will show, such indicator methods as ordinarily 

 employed are highly fallacious. AH a matter of fact the 



incident to the approach to the proMcm l>\ the latter method 



have long been familiar to the practical soap chemists, for they 



past determined the presence of " fn < alkali " 



free fatty acid " in their soaps by it .-thods The 



f'll\\inir observation not only -)i>\v how unreliable are the 



commonly employed indicator methods but why they must be so, 



