A Theory of the Aluminium Anode. 

 Table I. 



Solution of H 2 S0 4 =1 molar. 



.. KC1 =3*9 molar (saturated). 



305 



Voltmeter in 

 open circuit. 



™ , i , Voltmeter m 

 Mectrolyte. -. n . ., 

 J closed circuit. 



Current in 

 Amperes. 



11-7 voir. 



25 c.c. R,S0 4 11-6 



o-oi 



002 

 0-02 

 0-03 

 rising to 

 1-50 



„ " +0-19 c.c. KC1 . 11-6 

 +0-25 c.c. KOI J 11-6 

 +0-33 c.c. KC1 . 11-6 



falling rapidly 

 to 7-1 



11-7 volt. 



25 c.c. saturated ammonium 



alum solution 116 



„ +0-27 c.c. KC1. 9-4 



<001 



0-76 



The experiments were then repeated with more dilute 

 solutions o£ chloride and bromide. 



Table II. 



Solution of H^SO^l molar. 



KOI =0-39 molar. 



Voltmeter in 

 open circuit. 



11-7 volt. 



11-7 volt. 



Electrolyte. 



Voltmeter in 

 closed circuit. 



HJSO, ! 11-65 



, " +0-97 c.c. KC1 . 11-65 



4-2-0 c.c. KC1... falling to 7-0 

 , ., (fresh 



surface) ... falling rapidly. 



Current in [ 

 Amperes, j 



<0-01 

 001 

 rising to # 50 



rising to - 80 



25 c.c. H 2 SCv 



4-1-0 c.c. KC1. 

 4-1-2 c.c. KC1. 

 4-1-4 c.c. KOI. 

 4-1-6 c.c. KOI. 



11-65 

 11-60 

 11-60 

 11-60 



<O01 



0-025 (rising) 

 0-02 (rising) 

 0-02 (rising) 

 1-0 ^ 



In the second of these experiments the currents rose at 

 once to 1*0 ampere after addition of 1*6 c.c. KC1 solution. 

 but with smaller concentrations of chloride the current was 

 rather variable, as if the resistance of the film was continually 

 changing. In the case of bromide the current did not 

 increase until 5"0 c.c. of a QA molar KBr solution had been 

 added. It then rose steadily to 0'b ampere, but the increase 

 was not so rapid as with chloride. 



