ISOELECTRIC POINTS OF PROTEINS 



01 



the colloid will he rc'})r(ssc(l, aiul so tiic colloid will a])j)car basic, 

 i.e., will act as if composed of cations. On the other hand, treat- 



I 



^ 



n 



>•^ 



;.•'.:•.:••: 



'.••;•.•.:..••.: 



.••• '..'-.I 



Fig. 19. — Apparatus for demonstrating cata- 

 phoresis. The deeply shaded lower portion 

 of the u-tube is filled with a colloidal sol, the 

 upper part with ordinary distilled water. On 

 the passage of an electric ciu:rent the colloid 

 rises towards the electrode of opposite sign to 

 tiie sol. (Hatschek.) 



Fig. 20. — Apparatus for ultramicroscopic 

 observation of the movements of colloids in an 

 electric field (see Part II.). (Hatschek.) 



ment with a strong alkali will give the colloid acidic or anionic 

 properties. Hardy (1899) noticed that the particles of egg albumin 



