THE COLLOIDAL STATE. $$ 



selves upon coagulations also, and under favorable con- 

 ditions may evidence themselves even about fine suspended 

 granules. A satisfactory explanation of the fact that ten- 

 sion alone may make a honeycomb-like structure visible, 

 BUTSCHLI is unable to give, because of lack of observa- 

 tions directed toward this point. But surface structures 

 similar to those described above frequently appear in 

 different substances that have been stretched or com- 

 pressed, in part as an expression of the incomplete 

 mechanical homogeneousness of these bodies. Honey- 

 comb and fibrillar pictures are found on the surface of 

 stretched and compressed metals, and we can justly 

 put into this class also the cross-striated structures ob- 

 served by BUTSCHLI on delicate threads of Canada balsam, 

 without assuming, with this author, that this resin also 

 possesses a preformed honeycomb structure. Interesting 

 and worthy of further study as these observations may 

 be, they furnish conclusive evidence of the primary 

 honeycomb structure of colloids just as little as the 

 already described experiments dealing with the question 

 of rendering this structure visible. That we are dealing 

 with a true coagulatio'n whenever a structure is rendered 

 visible, and not, as BUTSCHLI thinks, with a condensation 

 of primary supporting walls, in a certain sense a more 

 advanced stage of simple gelation, is shown by the follow- 

 ing experiment, which to my mind is conclusive. 



In order to recognize its nature, let us recall to mind 

 the already discussed laws governing coagulation, on the 

 one hand, and gelation, on the other, under the influence 

 of combinations of electrolytes and non- electrolytes. 

 These two classes of substances add themselves alge- 

 braically in their effect upon gelation, while the coagu- 



