IX. Farther Researches on the Voltaic Decomposition of Aqueous and Alcoholic 

 Solutions. By ARTHUR CONNELL, Esq., F. R. S. Ed. 



(Read 15th February 1841.) 



SINCE my last communication to the Society on this subject, I have continued 

 my experimental investigation of the proposed law which limited the direct action 

 of the voltaic current to the solvent, in solutions of primary combinations of ele- 

 mentary bodies in the more important solvents. All my farther researches have 

 confirmed the rule in regard to aqueous solutions ; and I feel now fully convinced 

 of its truth, although, in the mean time, I have had occasion to see a different 

 view advocated by some other experimenters, to whose opinions I shall afterwards 

 advert. Neither have I seen any grounds for altering my views in regard to alco- 

 holic solutions. In regard to ether, some experiments which I shall afterwards 

 mention, have satisfied me that it would be improper at present to include that 

 solvent in any general rule. 



I. Aqueous Solutions. 



I need not revert to the proof adduced in my former papers* of the second- 

 ary decomposition of the hydracids in their aqueous solutions ; nor to that of the 

 secondary origin of iodine in a solution of bromide of iodine, f 



With respect to the oxyacids, in addition to the experiments on the sulphu- 

 ric, boracic, and iodic acids, formerly detailed, which led to the inference, from 

 the quantity of gases evolved, that such acids are not directly decomposed in 

 their aqueous solutions ;:f I have now to mention a still more direct method of ar- 

 riving at the same conclusion in regard to iodic acid, and, by analogy, in regard 

 to other oxyacids. A moderately strong solution of iodic acid, mixed with a starch 

 solution, was placed in the tube B, and was made positive by a power of 50 pairs 

 of two-inch plates ; whilst a starch solution placed in the tube A was made nega- 

 tive, the connection being by asbestos moistened with starch solution. Efferves- 

 cence soon ensued from both poles ; but in half an hour there was no trace of any 

 formation of blue matter at the negative pole or in any part of either tube. The 

 battery was then reversed, when blue matter appeared in two minutes on the 

 negative foil, without effervescence, or scarcely any. Thus, in the first position 



* Edin. Trans, vol. xiii. p. 339, and xiv. p. 116. t Ibid. xiv. p. 119. 



J Ibid. xiii. 338. Fig. 1, PI. II. vol. xiv. Edin. Trans., bottom of Plate. 



VOL. XV. PART I. S S 



