424 



remaining at first in the solid state. {Imbibition). The 'rate at which 

 the water is absorbed nia_y be determined by weighing. The first 

 stages of this process have been expressed in fig. 3. The line exhibits 

 a curvature, which points to a decrease of tlie velocity with which 

 water is absorbed with increasing water-content. When, however, the 

 water-content of the gel has attained a certain limit, a segregation 

 of the solid mass sets in ; it separates into flakes which become 

 smaller and smaller till at last a state is reached in which the 

 gelatin is uniformly distributed throughout the water {Solution). 

 This whole series of changes must be considered as a penetration 

 of the water between the gelatin pai-ticles, which are at first in 

 close contact with each other, which connection, however, is gradually 

 lost. So by the loords imbibition and solution two parts of the same 

 process are indicated. 



When dry gelatin and water are brought together at temperatures 

 above 30°, the same process takes place. At 30°, however, it is 

 more ttian 24 hours before the final state is reached; at higher 

 temperature the process is much quicker. 



Below 30° the velocity with which the water enters the gelatin, 

 is still much smaller. Here too it decreases with increasing water 

 content, but a consecpience of this is that a uniform distribution of 



TABLE III. 



Influence of the temperature on the velocity with which 

 100 mg. of gelatin dissolves in water. 



Temp. 



Duration of 

 the solution 



30° 

 35° 

 40° 

 50° 

 70° 



> 24 hours 



2'/2 » 



13 minutes 



±2 „ 

 + 2 



gelatin and water is no longer reached. Tiie lower the temperature, 

 the slighter the velocity with which water is absorbed, and ihe 

 smaller the water content at which the velocity becomes infinitely 

 small. The permanent state then reached is indicated as maximum 

 of imbibition. 



