THE COLLOID-CHEMISTRY OF SOAPS 111 



J. W. McBAiN and MILLICENT TAYLOR l observed the same facts 

 for sodium palmitate at 90 C. Their " acid " sodium palmitate 

 was first rendered " more colloidal " by the addition of sodium 

 hydroxid and was then salted out entirely in concentrations of 

 the hydroxid above 1.5 normal. 



F. GOLDSCHMIDT and L. WEISSMANN 2 also studied the changes 

 in viscosity of potassium soap solutions when various electrolytes 

 were added to them. With increasing concentration of the added 

 salt, they observed a marked increase in viscosity " with a strong 

 tendency to jelly." In a later study 3 they verify this finding 

 for the ammonium soap of palm kernel oil when various hydroxids 

 or salts are added to it. Recently G. H. A. CLOWES 4 has cor- 

 roborated these general findings for sodium oleate. He writes: 



"Na oleate was treated with salt at different concentrations, and it 

 was found that at .4 to .45M NaCl complete precipitation of the soap 

 took place. It was noted, however, that prior to precipitation a tendency 

 to jelly formation was exhibited in the zone from .2M NaCl to .4 or 

 .45M NaCl. . . . Further tests using varying proportions of soap, vary- 

 ing proportions of NaOH, and of NaCl and other salts of Na brought 

 out the remarkable fact that as long as the soap employed was not too 

 greatly diluted and was slightly alkaline, a jelly would be formed at all 

 point < between .2M Na and .45M Na, regardless of whether the Na 

 was derived from NaOH, from NaCl or other salts of Na." 



The explanations which the various authors offer of the phe- 

 nomena observed if they make the attempt at all are for the 

 most part extremely complicated. We confess to large inability 

 at times to understand just what they mean, for not only do the 

 different authors contradict each other but their individual con- 

 cepts are often self-contradictory. As well as we can understand 

 them, their views are about as follows: 



HOFMEISTER does not attempt to account for the jelly for- 

 mation at all, but considers the separation of tin- so :( p imm tin- 

 aqueous dispersion mlium as due to the " water-att m. -tinn 

 power" of the added salt. The soap, he hol<l>. i^ deprived of 

 its solvent because the added salt combines with the solvent. 

 This notion of H<MI INK has been much disparaged, but we 



1 J. W. McBAiN and MILLICENT TAYLOR: Zeiturhr f phynik. Chem., 76, 

 179(1911). 



I (ioLDCHMiDT and L. WEUSMANN: Zeii i i> 



(1912) 



GoLoecHMiDT and L. WEIMMNNN K,,ll,,,,i-/, ,t- hr . If, 18 (191 

 >WKS: Proc Soc. Exp. Biol. and Med , IS. 114 (1916) 



