, JACQUES LOEB 195 



IV. Further Proof that the Negative Osmosis Is Due to the Repelling 

 Action of the Ion with the Same Sign of Charge as that of the 

 Electrified Water Particles. 



When we fill the collodion flask with a m/256 solution of Na2S04 

 (made neutral or slightly alkaKne) and dip the flask into distilled water, 

 we notice a rather high initial rate of diffusion of water into the flask 

 caused by the fact that the attraction of the SO4 ion with its two 

 charges upon the positively charged particles of water is greater than 

 the sum of the repelHng action of the two Na ions. In higher concen- 

 trations of Na2S04 this difference becomes less (Fig. 4), as we assume 

 through the fact that for some reason the repelKng action of the Na 

 ions on the positively charged water particles increases more rapidly 

 with further increase in concentration than the attractive action of 

 SO4. If this assumption is correct the addition of a salt of the type 

 MgCl2 to a m/256 solution of Na2S04 should lower the rate of diffusion 

 •of water into the m/256 solution of Na2S04 more than the addition of 

 the same concentration of KCl; since the repelling effect of the biva- 

 lent Mg ion upon the positively charged water particles is greater than 

 the repeUing effect of the monovalent K ions. The addition of LiCl 

 should lower the rate of diffusion of water more than the addition of 

 KCl but less than MgCl2, since the electrostatic effect of Li is greater 

 than that of the K ion but less than that of the Mg ion. Fig. 14 

 shows that this is actually true. 100 cc. of m/256 Na2S04 (pH 

 about 6.0) contained 0, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 12.8, and 25.6 

 cc. of m/4 KCl, LiCl, or MgCl2. The addition of KCl caused only a 

 slight diminution in the rate of diffusion when 12.8 to 25.6 cc. of m/4 

 KCl were added. LiCl caused more of a drop, but a slight addition 

 of MgCl2 caused a considerable drop, as our theory demands. 



When, however, a salt with polyvalent anion and monovalent cation 

 like K4Fe(CN)6 is added to m/256 Na2S04 the attraction of the ferro- 

 cyanide ion for water counteracts to a large extent the drop caused by 

 the weak repelKng action of the K ions added. Fig. 3 shows that the 

 attraction of the Fe(CN)6ion for water is greater than that of the sul- 

 fate ion. Hence the addition of sHght quantities of K4Fe(CN)6 to 

 m/256 Na2S04 increases the initial rate of diffusion of water into the 

 solution but as soon as the concentration of K4Fe(CN)6 added reaches 



