474 Mr. "W. C» M. Lewis : Experimental Investigation 



that each ion is adsorbed equivalently we obtain the calcu- 

 lated value for the silver ion to be 



r Ag = 4*5 X 10~ 9 grm./cm. 2 



r Ag (found) = 2-5 x 10~ 8 grm./cm. 2 



The values for the experimental and calculated adsorption 

 are thus in much closer agreement than in any previous 

 case — the experimental being five times the calculated. The 

 question is : Does this represent a real discrepancy even in 

 this case, or is it to be considered as agreement within the 

 limits of experiment ? It is difficult to say, but without laying 

 too great stress upon it, I am of opinion that there is a real 

 (though small) discrepancy between calculated and observed 

 values. 



The Adsorption of Potassium Chloride. 

 Exactly similar determinations were carried out with this 

 substance as in the case c£ silver nitrate, except that with 

 this salt both the metal and acid were estimated. 



The Adsorption of the Potassium of Potassium Chloride. — 

 A very large quantity of oil was allowed to pass through the 

 KC1 solution in the large-drop apparatus. The resulting oil- 

 surface area was 16,000 cm. 2 The quantity of potassium 

 present in the solution before and after adsorption was 

 estimated as potassium sulphate. The difference in weight 

 of the K 2 S0 4 precipitate was 3*2 milligrams, whence the 

 adsorption of the potassium is 



T K = 8 x 10- 8 grm./cm. 2 

 A repetition of the experiment gave 



T K = 2 X lO" 8 grm./cm. 2 

 Thus the mean value is 



r K = 5x!0- 8 grm./cm. 2 



Calculation ofT K on Gibbs' 's formula : — 

 The values of the tension corresponding to different con- 

 centration (corrected for density) are given as follows : — 



Table III. — Hydrocarbon Oil — Potassium Chloride. 



Concentration 

 in gram-inoles per litre. 



Pipette 

 Drop-number. 



Tension 



dynes /em. 







135 



52 



0-0125 



139 



50-4 



0-025 



140 



49-9 



0-05 



143 



489 



01 



147 



47-8 



