adduced by Prof. Faraday.m support o/De la Rive's Theori^, 535 

 XII. I must not abandon this argument witiiout making 

 some observations respecting a singular proposition which is 

 read towards the end of the tenth page ot M. de la Rive s 

 work, expressed in the following terms : " Lorsque le hquide 

 dans lequel plongent les deux elemens du couple, est le meme, 

 il n'existe pas un seul cas dans lequel on ait yu le metal le 

 moins attaque etre positif par rapport a I'autre. 



Yet in the actual state of the science it is very easy to find 

 many cases in which it is not yet known which element ot the 

 pair maybe the most acted upon, although it may be un- 

 doubted that the pair itself produces a voltaic current Which, 

 for example, of the following substances— silver, gold, platina, 

 carburet of iron, and peroxide of manganese-is most acted 

 upon by distilled water? Yet, whatever pair may be made 

 with the said metals, there is a current when it is immersed 

 in the said liquid. If it be shown that charcoal, well freed 

 from hydrogen and extinguished for some time, may be more 

 acted upon by distilled water than the silver, gold and platina, 

 by which it may have to electrify itself, how does it happen 

 when positively voltaically united with those metals and im- 

 mersed in the' same liquid? If it be shown that charcoal 

 itself, when it is oxidated, may be less acted upon by distilled 

 water than the noble metals, yet made into a pair with them 

 it acquires negative electricity. If it be shown that tin may 

 be more acted upon than copper, nickel, bismuth, cobalt, and 

 iron, by the said liquid, yet tin becomes positive when im- 

 mersed in such liquid voltaically united with any one of the 

 said metals. Zinc united with cadmium is positive even in 

 distilled water. Is it known which of the two is most acted 



"^HereVthen, are at least twenty cases, all observed by me 

 separately, in which it is doubtful upon which of the two 

 elements of the pair the liquid exercises the sti-ongest chemi- 

 cal action; and it is very certain that one is electrified posi- 

 tively and the other negatively. And this number of doubtful 

 cases is doubled when it is observed, that when making use ot 

 alcohol instead of distilled water, the effects are different, 

 although the currents may in this case be weaker, ihe de- 

 scription of some experiments made with the said pairs may 



not be useless. 



not be useless. ., /. i ^ u i ^r 



A plate of platina, and one of silver, fixed to the ends of 

 the wire of the galvanometer, were immersed at the same 

 time in rectified alcohol, at thirty-three degrees of the scale 

 of Bauine, and there was a deviation of two degrees on the 

 part of the platina. Both the plates touched the liquid with 

 a surface of four square centimeters. 



