Electrolytes on Copper Colloidal Solutions. 589 



4. Kesults. 



A typical series of experiments on the effect of each of 

 the electrolytes was as follows : — The velocity of the par- 

 ticles in the pure copper solution was first taken ; gradually 

 increasing quantities of the chosen electrolytic solution 

 were then added to fresh samples of the stock copper solu- 

 tion and the corresponding velocity measured each time. 

 The measurement of one velocity was completed usually 

 within one hour of the addition of the electrolyte. All of 

 the salts used were Kahlbaum's purest and were not specially 

 re-tested. 



a. Potassium Chloride. 



In Table V. the velocities corresponding to the various 

 amounts of this salt are given. Column 1 gives the number 

 of grams of CI (as KC1) per 50 ccs. of colloidal solution, a 



i7»o (Too g rm «~ m °l') solution of KC1 being added drop by 

 drop ; column 2 gives the specific conductivity of the 

 mixture in each case. In the next column the velocities of 

 the particles (in cms. per sec. per volt per cm.) are written, 

 the positive sign indicating that the motion of the colloidal 

 particle was toward the cathode. In each table are included 

 particulars as to the coagulation caused in each case. 



Table V. 

 KC1 added to Copper Colloidal Solution. 



No. 



Grains of CI per 

 50 ccs. Cu Sol. 



Spec. Cond. 

 at 18° C. 



V lWO at Coagulation. 



1 



2 







3-OxlO" 5 



6-SxKT 5 



13-lxUT 5 



27-3 Xl0 -5 



8-2xlCT 6 

 11-7X10" 6 

 153X10" 6 

 22-OxlO" 6 

 34-2 xlO- 6 



+ 24-9XKT 5 

 +25-7X1CT 5 

 +26-2 xlO -5 

 4-22-8 xl0~ 5 

 4-18-7X10" 5 



No sign. 

 >> >» 



3 



4 



5 



Anticipating the results which follow, we shall find that 

 they confirm the fact that with colloidal solutions the particles 

 of which are positively charged, the negatively charged 

 ions are the ones to which the coagulative action is due ; 

 consequently the amounts of electrolyte are entered always 



in terms of the weight of the acid radical. 



