COLLOIDS AND LIFE 71 



''electrical influences are of considerable importance 

 in the study of colloids, but are here of a quite dif- 

 ferent kind from those with which electrochemistry 

 has hitherto chiefly concerned itself. We have to 

 consider here the so-called electrokinetic processes, 

 which do not appear at all in galvanic cells, and 

 only slightly in electrolysis."^^ 



The colloid particles have a tendency to unite to 

 form larger particles, the larger particles again 

 uniting to form yet larger aggregates, and to precipi- 

 tate, as their electric charges and other conditions 

 and the presence of a small amount of electrolyte 

 permit: There are the phenomena of coagulation, of 

 flocculation, etc. Some conditions, some sols, are 

 reversible, others irreversible. However, many dis- 

 perse systems are very stable. 



The foregoing is the briefest possible presenta- 

 tion of the leading facts concerning colloids. Ad- 

 vance in colloid chemistry has been rapid within 

 recent years, due to the work of Zsigmondy, Smo- 

 luchowski, The. Svedberg, Wolfgang Pauli, Herbert 

 Freundlich, Perrin, Hatschek, Martin H. Fischer, 

 and many others. 



However, certainly, since it is not questioned by 

 anyone today that the ultimate interpretation of 

 all physicochemical phenomena as well as of all 



^* The Elements of Colloid Chemistry, 75. 



