On the emulsifying action of soap.—A contribution to the theory of detergent action
AIthough the two closely allied subjects of emulsification and detergent action are of great importance in many brandies of technology, they seem to have been very little studied from a scientific point of view. Many technical chemists seem even now to bold the primitive and erroneous view that the detergent action of a soap solution is due to the saponification of grease by the alkali set free by hydrolysis. In the first edition (1893) of Thorpe's 'Dictionary of Applied Chemistry' it is stated that “the value of soap as a detergent is largely due to the fact that contact with water breaks up a neutral soap...” In the new edition (1913) no reference is made to any theory of detergent action. In neither edition is there an article on “Emulsions” or “Emulsification.” It is evident that the theory of these processes is in an unsatisfactory state, as regards both its actual development and its dissemination among those to whom it is of importance. The present paper is the beginning of an attempt at a systematic scientific study of the subject. The first section deals with some theoretical points relating to the process of emulsification, which are in part an amplification of views expressed by one of us in previous papers, and which are of importance in connection with the subsequent parts of the present paper. The second part deals with some experimental work which we have conducted during the last six months. The results of this work solve a fundamental problem in the theory of detergent action. In the third part is outlined a new theory as to the function of alkali in soap solutions.