JACQUES LOEB 



739 



We notice, second, that the attraction for water is greater in the 

 case of MgS04 than in the case of MgCl2, and greater in the case of 

 K2SO4 than in the case of KCl, showing that up to pH = 5.0 or 5.1 

 these salts attract positively charged water molecules. Hence the 

 action of the salts of Group B is due to the trivalent or tetravalent 

 cation and the H ion owes its effect not to any specific "adsorption" 

 but to the smallness of its "atomic radius," which gives it a high 

 electrostatic effect. 



On the other hand, a high degree of acidity of a solution of a salt 

 with a bivalent cation induces a negative charge in the water molecule. 

 This is true for beryllium salts. In this case the action of H ions is 

 simply added to that of the Be ions (which have a small "ionic ra- 



TABLE VII. 



Nature of solution. 



m/192 NasCOs.. 

 m/192 NaHCOa. 

 m/256 Na3P04.. 

 m/256 Na2HP04 

 m/256 NaHaPOi 

 m/256 H3PO4. . . 



pH 



9.2 

 11.0 

 12.0 

 8.6 

 4.2 

 2.4 



Concentration of balancing 

 cane sugar solution. 



Slightly above m/2 



" 3m/8 



" m/2 



" m/2 



m/16 



Less than m/64 



dius"), and the combined effect of both ions exceeds the effect of the 

 CI ions. We also notice that BeS04 acts less powerfully than BeCU, 

 as it should if in the presence of these salts water is negatively charged. 

 The Be salts therefore belong in Group B. We shall come back to the 

 effects of a mixture of two electrolytes in another paper. 



From what has been said it is to be expected that the substitution 

 of an H for an Na ion in the carbonates or phosphates increases the 

 cation effect owing to the fact that H has a smaller "ionic radius" 

 than Na (Table VII). 



It is obvious that in the two carbonates and the first three phos- 

 phates toward which (as we shall see in the next chapter) water is 

 positively charged, the attraction of the CO3 or PO4 for water dimin- 

 ishes the more the more H ions replace the Na ions, as our theory 

 demands. 



