I909.] 



The Dialysis of Colloidal Ferric Hydroxide. 



55 



treated in exactly the same manner, valuable conclusions may be drawn 

 from the collected results. 



The ferric hydroxide was suspended in a parchment sleeve in a glass 

 beaker through which distilled water was allowed to pass constantly. 

 When the wash water was analysed it showed the presence of large quan- 

 tities of ferric chloride. Chemical analysis of samples of the colloidal 

 solution showed that the ferric chloride was taken out during eight weeks' 

 dialysing until the formula changed from that given above to Fe2Cl6.r20 

 Fe:03. 



At certain fixed times during the course of the dialysis samples of the 

 ferric hydroxide were removed for chemical analysis; at the same time 

 a sample was prepared as indicated above and the velocity found. The 

 results of this series of experiments are tabulated in table I, in which we 

 have given in the various columns the results of the chemical analysis 

 (in terms of the ratio between the chlorine and the iron content of the 

 solution under dialysis), the resistance of the solution as it is taken from 

 the dialyser, and the velocity of the particles in the diluted sample of the 

 colloid. 



Table I. (Ferric hydroxide). 



* The chemical analyses for these solutions were not obtained. 



