54 



PHYSICOCHEMICAL BASIS OF PHYSIOLOGICAL PROCESSES 



tion, but are still visible when the ultramicroscopic illumination is 

 used, are called submicrons. They have a dimension between 0.1 fx and 

 1 /i/x (0.000,001 mm.),* and they constitute the colloids. Particles smaller 

 than 1 fx/x are called amicrons, this term being used to include the mol- 

 ecules and ions present in molecular solutions. (The amicron of hydro- 

 gen is, for example, computed to be 0.067 to 0.159 /*/*, and that of water 

 vapor, 0.113 /x/x.) This classification of dissolved substances according 

 to the size of the particles and molecules shows the relationship of one 



Su bmicrcmS 



1Q 



Colloidal <i°><i- 



Ma&Yi^itQtion r.'t.ooo.ooo 





/W\CTOY\S 



naa^'VicoAiow 1:3533 



Fig. 14. — Diagram from W. Ostvvald showing the relative size of various particles and colloidal 

 dispersoids compared with a red blood corpuscle and an anthrax bacillus. 



class of substances to others. An idea of the relative sizes of colloidal 

 particles and molecules in comparison with such familiar objects as a 

 blood corpuscle and an anthrax bacillus is given in Fig. 14. The fluid 

 in which the "particle" is suspended is called the dispersion medium, or 

 i eternal phase, and the particle itself the dispcrsoid, or infernal phase. 

 It is the enormous development of surface which determines the dif- 



V — 0.001 mm., and n/i = 0.000,001 mm. 



