592 Mr. E. F. Burton on the Action of 



e. Potassium Ferricyanide. 



The results (Table IX.) for this electrolyte 2 which also has 

 a trivalent acid radical, are in complete accord with those 

 given by the phosphate. 



Table IX. 

 K 6 (FeCy 6 ) 3 added to Copper Colloidal Solution. 



No. 



Grams of FeC y G 

 per 50 ccs. 



Ou Sol. 



Spec. Cond. 

 at 18° C. 



Yelocitj at 

 18° O. 



Coagulation. 



1. 







4-3X10- 6 



+30-4xl0~ 5 



■■ 



2. 



7-5 xicr 5 



7-6xl0~ 6 



+ 14-0X10" 5 



No. imnied. sign. 



3. 



150X10 -5 



9-3X10" 6 



+3-8X10- 5 



In one hour. 



4. 



22-5 XlO" 5 



13-OxlO- 6 



+ 1-0X10" 5 



„ 



5. 



30-0 X 10 " 5 



18-8X10" 6 



-1-5X10" 5 



v 



6. 



45-0 X 10" 5 



28-6X10-6 



-9-lxlO" 5 



» n 



We see that very small quantities of either potassium 

 phosphate or potassium ferricyanide are sufficient to reduce 

 the velocity of the copper particles to zero and even to 

 reverse the direction of their motion in an electric field. 



5. Collocation of Results. 



In order the better to illustrate the relation between the 

 number of molecules of the various electrolytes added per cc. 

 of the copper colloidal solution and the resulting velocity of 

 the copper particles in a given field, all of the results 

 recorded in Tables V. to IX. inclusive are brought together 

 in slightly different form in Table X., and illustrated in 

 the curves in figs. 3 and 4. Column 1 gives the numbers 

 from which the solutions may be identified in the above 

 tables. In column 2 is given the normality, in respect of the 

 electrolyte, of the mixture of the colloid and the electrolyte ; 

 i. e. the number of gram-molecules of the salt per cc. of the 

 mixture. According to the accepted dissociation theory, 

 we may look upon the salts in these extremely dilute 

 solutions as being completely ionized, and so the normality 

 as defined above will be directly proportional to the number 

 of ionized molecules of the particular salt per cc. However, 



