JACQUES LOEB 729 



sugar or dextrose caused only a slight rise in the level of liquid. This 

 excludes the possibility that the rise in liquid observed could be 

 ascribed to the gas pressure of the solute. 



A comparison of the relative rise of the Uquid in the tube in Table 

 I leads to a verification of the two rules, m/128 solutions of the 

 chlorides of the alkaHne metals cause a considerable rise, the rise in- 

 creasing with an increase in the "radius" of the cation in the order 

 Li, Na, K, Rb (Li having the smallest ionic radius). This agrees with 

 the assumption that water behaves towards these solutions as if its 

 molecules were positively charged and attracted by the anion and 

 repelled by the cation, the repulsion being the greater the smaller 

 the "ionic radius" of the cation. 



The most striking fact is that the m/128 solutions of the neutral 

 salts of bivalent metals cause no rise. In fact the water fell constantly 

 in the glass tube containing the solutions, since the initial pressure 

 head in the tube was always about 25 mm. of the column of solution. 

 Hence solutions of m/128 MgCl2, CaCl2, SrCl2, BaCl2, C0CI2, and 

 MnCl2 possess actually no attraction for water (beyond that caused 

 by the laws of gas pressure). This was to be expected since the pos- 

 itively charged water molecules are repelled more powerfully by the 

 bivalent than by the univalent cations. This difference between the 

 salts with univalent and bivalent cations exists not only in the case 

 of chlorides but also of nitrates and of sulfates (Table I), and, as we 

 shall see later, the hydroxides. The concentration of all solutions 

 except two used in the table was m/128. The sHght differences in 

 the osmotic pressure of the various solutions do not influence the 

 result, as we shall show in a later chapter. 



Table II shows that the attractive action of sodium salts increases 

 with the valency of the anion, as our rule demands. Table I also 

 shows that in the case of neutral salts with univalent and bivalent 

 cations the sulfates attract water more powerfully than the chlorides. 



Table I shows, moreover, that the salts with trivalent and tetra- 

 valent cations have a very powerful attraction for water, which we 

 should expect if water molecules behave like negatively charged 

 bodies towards solutions of these salts. 



