98 



ELECTRIFICATION OF WATER AND OSMOTIC PRESSURE 



the equilibrium between non-ionogenic gelatin and the metal gelati- 

 nate formed.^ 



Fig. 3 gives the rise of level of liquid in the manometer during the 

 first 12 hours for a 1 per cent NH4 gelatinate and a 1 per cent Ba 

 gelatinate solution. Equilibrium was reached after about 6 hours. 

 The slight diminution of osmotic pressure due to the fall of pH on 



B 



CO 



in 

 \n 

 <^ 



O, 120 



o 



•<— • 



■»-> 



o 

 £ 



O 



260 

 240 

 220 

 200 

 180 

 IGO 

 140 



100 

 80 

 60 

 40 

 20 



01 23456768 10 11 



Time in hours 



12 



Fig. 3. Curves of rise of osmotic pressure of 1 per cent solutions of NH4 and 

 Ba gelatinate (pH = 8.8). Pressure in mm. of column of gelatin solution. 



account of CO2 action did not commence until later. The osmotic 

 pressure of the 1 per cent solution of NH4 gelatinate is in this experi- 



» In order to make sure that the osmotic pressure reached is permanent, the 

 experiments with metal gelatinates should be made with the exclusion of CO2. 

 Since, however, this source of error does not exist in the case of gelatin acid salts 

 where the permanency of the final pressure reached can be made sure of, and since 

 the results in that case are the same, as we shall presently see, and since the 

 error was less for Ca and Ba gelatinate than for Na gelatinate, we need not dwell 

 upon this point. 



