Prof. Connell on the Voltaic Decomposition of Watei'. ^1 



restriction of Mr. Faraday^s beautiful law of the detinite de- 

 composing agency of the galvanic current. It may not per- 

 haps be altogether superfluous to state, that it is now nearly 

 fourteen years since I read to the Chemical Section of the 

 British Scientific Association at Glasgow a notice of experi- 

 ments to precisely the same effect, although from which assu- 

 redly no inference was drawn affecting Mr. Fai-aday's law ; and 

 which notice was afterwards inserted, in January 184-1, in the 

 18th volume of this Journal, page 49*. My object at that time 

 was to illustrate the voltaic decomposition of alcohol, by showing 

 that the quantity of hydrogen liberated from the negative pole 

 in acidulated water was the same as that liberated from the 

 negative pole in alcohol, having its conducting power improved 

 by the solution in it of minute quantities of potash or of potas- 

 sium; my inference from the whole experiments on the subject 

 being, that it was the water of the alcohol, considered as a hydi-ate 

 which suffered voltaic decomposition. To obtain this compara- 

 tive illustration of that view, it was shown that certain parti- 

 culars required to be attended to, and that two circumstances 

 seemed to modify the result : first, the absorption of hydrogen 

 by the fluid, which hydrogen entered into the constitution of the 

 secondary products of oxidation formed at the positive pole j and 

 secondly, that when the conducting power of the liquid dimi- 

 nished, the galvanic action diminished also, " a result," I added, 

 " which may be imitated by passing the same current through 

 distilled water, and water acidulated with sulphuric acid, when the 

 hydrogen liberated from the pure water will be found to be notably 

 less than that from the well-conducting fluid." Here, then, we 

 have precisely the same experiment made and published about 

 fourteen years ago, which is now brought forward as new by 

 M. L. Foucaultf. 



On looking back to my notes of the experiment here referred 

 to, I find more than one taken down, and all to the same effect. 

 The following I find amongst them. Two tubes with platinum 

 wires terminated by platinum foils, sealed hermetically in their 

 closed extremities, were filled with distilled water and inverted 

 in a suiall evaporating basin also containing distilled water, and 

 secured in that position. Two other similar tubes were filled 

 with distilled water acidulated with j^-^i\\ of sulphuric acid, and 

 inverted in another evaporating basin containing acidulated water. 

 Connexion was then made by a wire between the wires of two 

 of the tubes, one in each basin ; and the wires of the other two 

 tubes were connected respectively with the poles of a Cruik- 



* 111 the eighth hne of that page for rigorous read viyoroas. 

 t M. Foucault's notice was read to the Academy of Sciences, Feb. 20, 

 18.54. Cosmos, vol. iv. p. 249. 



