228 SOAPS AND PROTEINS 



E. LACQUEtTR, O. SACKUR, 1 L. L. VAN SLYKE, 2 A. W. BOSWORTH, 3 



T. B. ROBERTSON, 4 etc. 



The difficulty with the work of these authors, if we may express 

 an opinion, is that with developmnt to quantitative levels of their 

 chemical views covering such protein/electrolyte/water systems, 

 they have seemed constantly to support the expressed or implied 

 view that with -the pure chemistry of these systems settled, an 

 understanding of their colloid-chemical behavior followed as a 

 self-evident corollary. 



This view is, we think, fundamentally false. While union in 

 stoichiometrical relations, qualitative and quantitative changes in 

 electrical charge, the accepted theories of " dilute solution," etc., may 

 all at times be factors appearing in a colloid system and may, in fact } 

 in part determine the behavior of colloid systems, their quantitative 

 appraisement is in no instance adequate to " explain " the colloid 

 state. The colloid properties of a casein/sodium hydroxid/water 

 system (ignoring for the present the presence of an overplus of 

 either alkali or casein) are those of a sodium caseinate/water sys- 

 tem and these, depending solely upon the concentration of the 

 water in the system, vary from the extreme of a gelatinous solu- 

 tion of water in the caseinate on the one hand to a true solution 

 of sodium caseinate in water on the other. 



It is well to emphasize at once the proper significance to be 

 given the electrical, ionic, viscosity, etc., properties which such a 

 system may show. In the presence of sufficiently little water a 

 chemically neutral sodium caseinate is not only solidly gelatinous 

 but also neutral to an indicator like phenolphthalein, as witness 

 the lower section of the test-tube shown in Fig. 110. While 

 this finding is commonly interpreted in the terms of orthodox 

 physical chemistry as proof that in such " highly concentrated 

 solutions " (as in the highly concentrated soaps), there is no ade- 

 quate hydrolysis and electrolytic dissociation to yield an overplus 

 of OH ions, we ourselves hold that it is just as correct and more 



1 E. LACQUEUR and O. SACKUR: Hofmeister's Beitr., 3, 196 (1902). 



2 L. L. VAN SLYKE and co-workers: Am. Chem. Jour., 33, 461 (1905); 

 ibid., 38, 393 (1907). 



3 A. W. BOSWORTH and L. L. VAN SLYKE: Jour. Biol. Chem., 14, 203 (1913); 

 ibid., 19, 67 (1914); BOSWOHTH: ibid., 20, 91 (1915). 



4 T. B. ROBERTSON: Jour. Biol. Chem., 2, 317, 337 (1907); ibid., 5, 493 

 (1909); ibid., 8, 287 (1910); Physical Chemistry of the Proteins, 85, New 

 York (1918). Here references to the older literature may be found. 



