96 



ELECTRIFICATION OF WATER AND OSMOTIC PRESSURE 



solution. In Table I the level of the water in the manometer tube after 

 30 minutes is given for the different 1 per cent gelatin solutions. The 

 plus sign means a rise in the level of water in the cane sugar solution 

 above the original level of 25 mm., the minus sign means a fall of the 

 level of the sugar solution in the manometer tube. 



We notice that the concentration which a cane sugar solution must 

 have to balance osmotically 1 per cent solutions of gelatin salts with 

 monovalent cations of a pH of about 7.0 lies between m/8 and 3m/32, 

 while for Ca gelatinate of the same concentration and pH the balanc- 

 ing concentration of cane sugar has a value between m/32 and m/16, 



TABLE I. 



Nature of gelatin salt used. 



Li gelatinate 



Na 



K 



NH4 " 



Ca 



Ba " 



Change of level of liquid in the manometer tube of different concen- 

 trations of cane sugar solution when immersed in 1 per cent solu- 

 tions of different metal gelatinates of pH 7.0, after 30 min. 



Concentration of cane sugar solution. 



mm. 

 -16 

 -17 

 -22 

 -20 

 -18 

 -15 



and for Ba gelatinate a sUghtly lower value. We may, therefore, 

 state that the balancing concentration of cane sugar is roughly over 

 twice as great when the metal gelatinate has a monovalent cation as 

 when it has a bivalent cation. Since water diffuses towards a cane 

 sugar solution with a velocity which in the beginning of the experi- 

 ment increases in proportion with the concentration of the sugar, 

 we can say that the rate of diffusion of water into 1 per cent solutions 

 of gelatin salts of the type Na gelatinate is between two and three 

 times as great as the rate of diffusion of water into a solution of Ca 

 or Ba gelatinate of the same concentration and pH. 

 The question now arises; Is there a similar difference between the 



