70 WHAT IS LIFE 



particles are the same for liquids and gases. The 

 resistance offered by the medium to the movement 

 of a particle-of-a-given-size through it is, of course, 

 much greater in liquids than in gases. A kinetic 

 theory of liquids that answers to the kinetic theory 

 of gases, and Einstein's Brownian movement equa- 

 tion, then, account for the displacements of the 

 particles of the disperse phase of a sol. Research on 

 Brownian movement in gases by R. A. Millikan 

 resulted in the exact evaluation of the gram-molecule, 

 the Avogadro constant N (Loschmidt number L). 



As for the particles of the disperse phase them- 

 selves — they always acquire electric charges, even 

 in pure water (several and various factors contrib- 

 uting), and wander to poles. That colloids carry 

 electric charges was first shown some thirty years 

 ago (Linder and Picton), and was, as Stieglitz 

 states, "one of the most important discoveries made 

 on colloids."" 



It appears that the phenomenon of electricity in 

 colloids, that is, of a charged colloid particle, is in a 

 class by itself. Faraday's laws do not apply to col- 

 loids; and there is no known method of determining 

 the amount of the charge carried by an individual 

 particle. Electrokinetic processes are inseparable 

 from colloids. According to Herbert Freundlich, 



" Qualitative Chemical Analysis, 131. 



