Voltaic Electricity on Alcohol, Sfc. 343 



A moderately strong solution of recently prepared and colour- 

 less hydriodic acid was placed in A, and connected with the ne- 

 gative side of fifty pairs of two-inch plates. Distilled water was 

 placed in B, and connected with the positive side ; and the con- 

 nexion was made by asbestus, moistened with distilled water. A 

 slight effervescence ensued from both poles. During the first ten 

 minutes, there was no appearance of discoloration of the liquid 

 in either tube. A slight yellow tint then appeared in the positive 

 liquid, and no change in the negative, and shortly after, a just 

 perceptible acid reaction on test-paper was observed in the posi- 

 tive liquid. In a quarter of an hour, the battery was reversed in 

 the manner already described as to muriatic acid. Instantly, not- 

 withstanding the diminished action of the battery, the hydriodic 

 solution which had been previously colourless, acquired a brown- 

 ish colour round the positive pole, and not a bubble of gas ap- 

 peared from that pole, whilst gas rose from the positive foil. The 

 brown colour gradually diffused itself through the liquid. 



This experiment was now repeated with the difference that 

 the level of the distilled water was made about a line higher than 

 that of the hydriodic solution, which was perhaps a little weaker 

 than in the preceding experiment. A slight evolution of gas 

 soon arose from both poles, and in a quarter of an hour there was 

 not the slightest discoloration of the liquid in either tube, nor 

 did the water shew any acid reaction. The battery was then re- 

 versed. The hydriodic solution was immediately discoloured 

 round the positive foil as before, without any liberation of elastic 

 fluid, whilst there was a slight effervescence from the negative 

 foil. 



This last experiment was repeated with a power of thirty-six 

 pairs of four-inch plates, with precisely the same result. 



The explanation of these experiments seems very apparent. 

 When the hydriodic acid solution is in connexion with the nega- 

 tive side, and the water with the positive, water is resolved into 



