THE COLLOID-CHEMISTRY OF SOAPS f.9 



2. On the Theory of Soap Gels 



It is our purpose now to show thai the behavior of the soap/ water, 

 soap/alcohol and soap/x systems previously discussed is also best 

 understood in the terms of the submolecular dispersion into each 

 other of two materials possessed of a fair degree of mutual solubility. 1 



\Vhen one tries to state in the simplest possible terms what it 

 is that happens when a definite mixture of soap with some solvent 

 (like soap and water), whirh at the temperature of boiling water 

 is a mobile liquid, is seen to set into a dry, solid mass as its temp- 

 erature is reduced, it seems easiest to think of the whole as a 

 change from what is, at the higher temperature, essentially a 

 si tint ion of soap in water to that which is, at the lower temperature, 

 a solution of water in soap. Between these extremes and as 

 determined by the temperature and by the relative concentra- 

 tions of soap and of water, we get various mixtures of solvated- 

 soap in soap-water or of soap-water in solvated-soap. The situa- 

 t inn in t he case of the soaps in the presence of limited volumes of 

 water is identical, in other words, with the changes which may 

 be seen in mutually soluble systems of the type phenol water, 

 eth.-r water or protein/water as studied by J. FRIEDLAMM-K. 

 V. ROTHMUND, W. B. HARDY and their various follower 



ruining first to a study of the mechanism employed for the 

 production of these colloid soap systems, it is evident that they 

 are formed for the most part by "dissolving" a unit weight of 

 soap in a definite volume of water at a rather high temperature. 

 In the accepted parlance, it may be said that through increase in 

 rut me the solubility of the soap in the water i- tremrn- 

 <i<ii-l\ increased. While the l\\er soaps of the acetic n.-i-l 

 are readily soluble in --u at relatively low temperatures), 



the upjM-r members behave like the lower member- it" the 

 ture is raised. The soap goes into solution /// the water. The 

 truth of this assertion is indicated by the available physico- 



are not unaware that the concept "iolution " needs itself to be defined 



Wink thi- firl.l of *,luti,m ,',,n*fitut.-s sl.p.-rv K r..un.|. .- MXWfX, lW 

 pragmatic reasons, M character ? , on , the tearhtnipi of 



\V..i.-.,\\.i OH- M.> :inl I' I' \.s WuMMtv uh.. .l.-lmr .i.h ntetiOM M 

 dfapenioot of A in B with the defree of mibdivWon meairable in molecular 

 or nailer valuer To cxprew the matter in the tcrnm of A I* M niEwa, 

 we may aay that A is dissolved in B or vice vena when the solvent has over- 

 come the cohesive forces of the dfceorved substance \ MM 



