426 



billion of gelatin and water, hence a trne eqnilibrinin ; below 3T)° 

 this uniform distribution has not yet been reached in the final state : 

 the inaxhnwn of imbibition is an apparent equilibrium. 



Besides, by the above considerations the validity of this thesis is 

 proved by the fact that the maximum of imbibition entirely lacks 

 the characteristics of a true equilibrium. When a sheet of gelatin 

 that has imbibed water, is heated with the water to such a 

 temperature that a uniform distribution of water and gelatin 

 takes place, and then cooled down again to the original temperature, 

 there is no question of a separation into two phases, water and 

 "gelatin of maximum imbibition." To be sure a true equilibrium is 

 not established in the solution then either, but the uniform distribution 

 is retained. Besides it is, however, possible to show that at every 

 temperature by the side of water not only a single "maximum of 

 imbibition" can exist, but an infinite number. Which of them is 

 reached in each special case depends on tlie state in which the 

 gelatin is brought together with the excess of water. 



It has appeared in table 4 that anhydrous gelatin at 12° reaches 

 the final state in water, when a ten-fold weight of water has been 

 absorbed. When a lOVn gelatin-gel, prepared by dissolving anhydrous 

 gelatin at 70°, and then cooling it, is brought into an excess of 

 water, the weight remains by no means unchanged. An important 

 quantity of water is absorbed, and with the exception of the first 

 hours, at a rate which exceeds the imbibition of dried gelatin. The 

 determinations have not been carried on till a permanent state set 

 in, but the gradual diminution of the velocity suggests that it must 

 really exist, and then not a lÜ7o, but a 5"/^, gel remains unchanged 

 by the side of water. 



It is found in the same way that also a 5"/^ and a 27o gel 

 increases in weight in excess of water. 



TABLE V. 



Influence of the concentration of the gel on the rate at which it imbibes 



at 12°. Quantity of water which 1 gr. of gelatin has absorbed. 



anhydrous 

 gel 



after 5 hours — gr. 

 „ 20 „ I 10.65 „ 



44 

 68 

 92 



11.01 „ 

 10.98 „ 



lOO'o gel 



12.68 gr. 

 16.59 „ 

 17.95 „ 

 18.47 „ 

 18.70 „ 



5% gel 



20/0 gel 



23.85 gr. 

 28.23 „ 

 31.62 „ 

 32.80 „ 

 33.80 „ 



66.90 gr. 

 94.70 „ 

 96.00 „ 

 97.10 „ 



