ASPECTS OF ADSORPTION PHENOMENA 191 



conductivity at frequent intervals, the curve, which is in fact a straight 

 line, shows no kink of any kind at the point where the hydrogel 

 liquefies to a hydrosol. 



The experiment previously described on the relations of gelatin 

 to calcium sulphate was continued as follows : -The two flasks con- 

 taining gelatin and calcium sulphate were warmed to 53, the rise of 

 conductivity in the case of the washed gelatin was 397'2 gemmhos, in 

 the commercial gelatin 1317 gemmhos. Now the point of interest is, 

 whether this rise is greater than would be the case if no separation of 

 additional electrolyte had taken place under the influence of heat. To 

 decide this, solution of calcium sulphate was prepared, having at 

 10 the same conductivity as the solutions in contact with the two 

 kinds of gelatin. These were then warmed to the same temperature 

 as the gelatin. The rise of conductivity in the more dilute amounted 

 to 376 gemmhos, and in that of the stronger to 1446 gemmhos. 

 There is therefore an increase in electrolytes in the case of the washed 

 gelatin corresponding to a difference in conductivity of 21 gemmhos. 

 It is to be remembered, moreover, that gelatin in the state of hydrosol 

 has a slight effect similar to that of other non-electrolytes in diminish- 

 ing the conductivity of solutions in which it is present. This is, no 

 doubt, due to an increase of internal friction in some way or other, 

 and amounts, according to determination I have made, to 3-4 percent, 

 diminution of conductivity for each i per cent, of the gelatin present. 

 So that each of the values for the gelatin solutions should be increased 

 by, approximately, 3-4 x 4*9 per cent., the gelatin solution being 4-9 

 per cent, in concentration. This increases the two values to 463 and 

 1536 gemmhos. The differences in favour of the gelatin come out 

 now to be 87 gemmhos for the washed, and 90 gemmhos for the 

 commercial sample. The closeness of these two numbers serves to 

 strengthen the view that the elecrolytes causing the increase were in 

 some way separated off from the gelatin under the influence of heat. 



It has been shown above that the conductivity of a solution of 

 the ash from a given sample of gelatin is greater than that of the 

 solution with which the gelatine is in equilibrium. I thought it 

 interesting, therefore, to compare the ash of the particular ' washed ' 



