]^30 MR CONNELL ON THE ACTION OF VOLTAIC ELECTRICITY 



solution. Let us see liow far this result, whicli we thus predict, is supported by 

 experiment. 



Absolute alcohol, with about i\, of iodide of potassium in solution, was placed 

 in a glass tube of 1^ dram measure, and on each side a glass cup containing a cjuar- 

 ter of an ounce of water was connected Avith it by means of asbestus moistened with 

 alcohol, one of these cups being made negative and the other positive by fifty 

 pairs of 2-inch plates. The arrangement is represented in Fig. 3, B containing 

 the alcohohc solution and A and C the water. In eight minutes iodine began to 

 appear in C round the positive pole, with efiervescence at both poles. After forty 

 minutes' action, not a trace of acid or of alkali could be detected in the alcoholic 

 solution in B, nor had either been observed all along in that liquid. On the other 

 hand, alkali had been noticed soon after the commencement, and all along at the ne- 

 gative pole in A ; but no acid reaction was any Avhere observed.* At the conclusion 

 of the experiment, in forty minutes, free iodine was very manifest in C both by 

 the colour and smell ; but not a trace of it was observed either in B or in A. 



This experiment was repeated witli a power of seventy-two pairs of 4-inch 

 plates, and three tubes, each of the size of 1^ dram, all other circumstances being 

 the same. Iodine began to appear in C in about foiu- minutes, with bubbles at 

 both poles. In eighteen minutes neither acid nor alkali could l)e detected in the 

 alcoholic solution in B ; l3ut a trace of acid was noticed on the asbestus above the 

 surface of the positive water in C, and alkali had appeared before this at the ne- 

 gative pole. In three quarters of an hour there was still no acid nor alkali in B, 

 whilst the acid reaction was strong at the place where it had previously appeared. 

 There was then much free iodine in C ; and in B only an insignificant trace of that 

 partial discoloration to which I formerly alluded as probably proceeding from some 

 subordinate and trifling secondary action. 



Let us now contrast these results with those obtained with an aqueous solu- 

 tion. 



Water containing j\, of iodide of potassium was substituted in B for the aU 

 coholic solution, all other cu'cumstances, including the size of the vessels and vol- 

 taic power, being exactly the same as in the former of the two preceding experi- 

 ments. The lu'st decided acid reaction which was now observed was on the po- 

 sitive side of the solution in B, with alkali on the asbestus between A and P, and 

 these in about fifteen minutes, effervescence having been in the mean time going 

 on at both poles. During forty minutes only slight traces of acid appeared at the 

 positive pole and on the asbestus between B and C, whilst a strong acid reaction 

 continued in the liquid in B, with alkali at the negative pole, and on the asbestus 

 between A and B. A slight discoloration of the water in C had just commenced 

 at the end of this time, without any change of tint in A or B. 



In explanation of the non-appearance of acid in the water in this experiment, see p. 15, 16. 



