J28 MR CONNELL ON THE ACTION OF VOLTAIC ELECTRICITY 



day this remnant of that celehrated controversy still, in some measnre, divides 

 the chemical world, although undouhtedly the view that chlorides exist as such 

 in solution has latterly gained ground very considerably, and numbers amongst 

 its supporters many of the most distinguished British and foreign chemists. Be- 

 fore, therefore, venturing to state those galvanic experiments which appear to me 

 to lead to the opposite opinion, I would wish, first, to advert very briefly to some of 

 those argimients which have been adduced within the last few years in support of 

 the existence of chlorides in aqueous solutions, for the purpose of inquiring whe- 

 ther any of them is of such force as to admit of no answer, and consequently may 

 induce us to presume some fallacy in views leading to a contrary conclusion. 



M. Dumas has argued, that because ether can separate the chlorides of iodine, 

 of gold, of mercury, &c. from water, they must therefore exist in Avater in the 

 same state in which they are dissolved in ether, i. e. as chlorides*. To this argu- 

 ment, the answer which Berzelius suggests for the use of the advocates of the 

 opposite doctrine, although not himself a supporter of it, seems sufficient ; the 

 affinity of ether for the cliloride may determine the decomposition of the muriate 

 and the formation of water f. 



Matteucci supposed, becaiise he found that a weak voltaic power, which 

 \\'as incapable of decomposing acidulated water, produced, in aqueous solutions of 

 metaUic chlorides and iodides, metal at the negative pole, and chlorine or iodine 

 at the positive, that, therefore, the chlorides and iodides had existed as such in 

 solution, t This result is easily explained, on the view of a secondary action con- 

 sistently with the solution of a m\u-iate and hydriodate. The affinity of hydro- 

 gen for the oxygen of the oxide, and of oxygen for the hydrogen of the acid, leads 

 to the voltaic decomposition of water in these circumstances, although, in the 

 ordinary case, it might not occur with the power used ; and a secondary production 

 of metal and chlorine or iodine ensues. 



An argument much more effective than either of the preceding, is one brought 

 forward by Berzelius, in noticing that of Dumas. ^ A solution of chloride of so- 

 dium evaporates at common temperatures, and leaves dry chloride of sodium. If 

 a muriate was dissolved, then the tension of the water formed from the oxygen 

 of the base, and hydrogen of the acid of the muriate, has come into play before 

 its elements were united as such ; or if it be said that this view involves no im- 

 possibihty, still such tension must be admitted to be weaker than that of ready 

 formed water ; and yet chloride of sodium begins to be deposited by a saturated 

 solution whilst water stUl remains. Considering the ingenuity of this argument, 

 as well as the authority from which it comes, it is with hesitation that I at- 



• An. Ch. et Phy. xliv. 271. t Jahrsbericht, xi. 56. 



X An. de Ch. et Phy. xlv. 324. Jahrsbericht, xi. 57- 



