584 



The Precipitation of Colloids. 



It thus seems probable that the minimal concentration of 

 anions is given by an equation of similar form to that for 

 cations. 



Fig. 3. 



20 





fBr 





ci7 















• 





1-5 



LogN 



1-0 



2-0 



Log C 



To summarize the results obtained : — 



(1) The minimal concentration of univalent cations 

 required to precipitate a negatively charged colloid under 

 similar conditions of concentration and temperature in a 

 given time varies with the atomic number of the cation and, 

 in general, is given by an equation of the form 



C = K.N n . 



