133 



results were obtained. With carmine the network of par- 

 ticles stayed after thawini>', which fact the author attributes 

 to the adhesion caused by the pressure exerted by the ice. 

 The Brownian movement of the carmine particles had 

 ceased. 



2. Colloids. Bruni (1909) described colloidal isingiass 

 and colloidal silicic acid in the frozen state as consisting of 

 colloidal particles interspersed with ice crystals. In silicic 

 acid the two phases, one of which was pure water, remained 

 separated after thawing. 



]\Ioran (1925) noticed that, after a congelation, followed 

 by melting of the ice, tlie liquid portion of the white of egg 

 had increased and the colloidal portion had decreased. He 

 compares this phenomenon with the exudation of water 

 from gelatin, from jellies and from the muscle, after thaw- 

 ing. 



According to Molisch (1897), a layer of a gelatin gel 

 frozen on a slide, under the microscope, allows one to ob- 

 serve the ice separated from the gel. There remains a 

 gelatinous network with ice particles in the meshes (Fig. 

 9). After thawing, the meshwork can be preserved for 



Fig. 9. Network left after the thawing of a frozen gelatin solution. 

 (From Moliseh, 1897.) 



several days if the water content of the gel is low ; it can 

 also be fixed as a tissue, by formol, and kept indefinitely. 

 With higher water contents, a reimbibition takes place and 

 the meshwork disappears. 



Bobertag, Feist and Fischer (1908) observed that, on 

 thawing solutions of gelatin, carrageen, agar agar, isin- 



