THE COLLOID-CHEMISTRY OF SOAPS 65 



Of these dispersoids, the ones of greatest interest in con- 

 nection with the behavior of the soaps are those embraced within 

 the heavy black square, in other words, those which have the 

 composition liquid plus liquid or liquid plus solid. According 

 to OSTWALD, the former are the emulsion colloids, the latter the 

 suspension colloids; or, to adopt the terminology of P. P. VON 

 WEIMARN, they are the emulsoids and the suspensoids. 



The attempt has been made to correlate the physical properties 

 of each of these systems with the fact that the two phases have, 

 in the first instance, a liquid plus liquid composition, or, hi the 

 second, a liquid plus solid composition. In the group of the 

 first are found many of the " viscous, gelatinizing and not readily 

 coagulable " " colloid solutions " of A. A. NoYES, 1 or the hydro- 

 philic or lyophilic colloids of J. PERRIN 2 and H. FREUNDLK n; ' 

 in the second are the " non-viscous, non-gelatinizing, readily 

 coagulable " " colloid suspensions " of NOYES or the hydrophobic 

 or lyophobic colloids of PERRIN and FREUNDLICH. The cor- 

 relation between the physical state of the phases and the prop- 

 erties of the mixed systems is not enough, however, to characterize 

 them completely. Liquid mercury in water for example yields 

 only a suspension colloid, and the same is true of (liquid) oil in 

 water; on the other hand, (solid) ferric hydroxid, generally ranked 

 unions the suspension colloids, has distinctly hydrophilic proper- 

 ties in high concentration in water. 



Such weaknesses in the attempts to make the term lyophilir 

 colloid synonymous with omul-inn colloid and lyophobic colloid 



with suspen>ion colloid were recognized by WOLFGANG OSTWALD 4 



himself, and in consequence the effort was made by him to 

 overcome such objection by declaring the lyophilic colloids 

 " colloids of a higher order." Specifically lie assumed that, 

 emulsion colloids were not, merely" subdivisions of one liquid 

 in a second, but that each of the liquid phases was itself a dis- 

 persoid. We shall see below that this view is correct. 



It seems to us that the characteristic difference between ///</>/ ///r 

 and lyophobic colloids is not to be souyht in their liquid />//> lif/uid 

 or ln/uid i>lns W/W character bid in the fact that the phases are either 



'A. A. NOTES: Jow \m Chan s . 27, 86 (1906). 



1 .1. l' RUIN .li.iirn.-il .! ( limn.- |ih\si<|ue, 1, R4 (1906). 



' II K.-.M NDI i. H Koii.,i,i-/r,iM-hr. t 1, 80 (19W); KapOfenbonfe, 30B, 



I I'.KW). 

 OLTOANO OOTWALD: Kolloid-Zcitachr., 11, 230 (1912). 



