214- Mr. Napier on the Decomposition of 



gas evolved at the negative pole, but is not an equivalent for 

 the silver dissolved from the positive. 



In case of any absorption of gas in the negative cell pro- 

 ducing an erroneous result, I charged the negative division with 

 a solution of sulphate of copper, in which was immersed a cop- 

 per electrode, the amount of metal deposited being taken as 

 the measure of electrolyzation in this cell ; the positive divi- 

 sion was charged with a solution of cyanide of potassium, in 

 which was placed a silver electrode, the whole being attached 

 to a single pair of zinc and copper elements excited by a so- 

 lution of sal-ammoniac. In the three following experiments the 

 current was only continued one hour for each : — 



I. II. III. 



Copper deposited on the negative electrode 5*0 grs. 6-2 grs. 5*5 grs. 



Silver dissolved from the positive electrode 37"0 ... 39'3 ... 40*7 ... 



Zinc dissolved in the battery 5-8... 6 5... 6-3... 



In these experiments we have nearly two equivalents more 

 dissolved from the positive pole than is deposited upon the 

 negative. 



Another experiment with the same electrolytes, but both 

 positive and negative electrodes being pure copper, the cur- 

 rent was continued for sixteen hours, — 



The negative electrode had gained . 22 grs. 



The positive electrode had lost . . 75 ... 



The zinc dissolved in the battery was 25 ... 

 Here we have upwards of three equivalents dissolved from the 

 positive pole to one deposited upon the negative; in all these ex- 

 periments the cyanide of potassium was in the proportion of 

 40 grs. to the ounce of water. 



In the three following experiments hydrochloric acid was 

 used in the positive division instead of cyanide of potassium, 

 the negative containing a solution of sulphate of copper; the 

 battery consisted of a single pair excited with a solution of 

 common salt: — 



I. Hydrochloric acid in the proportion of 1 ounce to 12 of 

 water, the current kept up for eighteen hours, — 



Deposited upon the negative electrode 15 grs. 

 Dissolved from the positive electrode .22 ... 

 Zinc dissolved in the battery . . . 18 ... 



II. Hydrochloric acid, 2 to 12 of water, current passing for 

 tw e n ty-fo u r hours,— 



Deposited upon the negative electrode 40 grs. 

 Dissolved from the positive electrode , 62 ... 

 Zinc dissolved in the battery . . . 48 ... 



