Definite Chemical Action of Electricity, 335 



entering into further detail respecting that substance, or even 

 summing up the results here (732.). I refer, therefore, to the 

 whole of the subdivision of this series of Researches which 

 contains the account of the volta-electrometer, 



786. In the next place, 1 also consider the law as esta- 

 blished with respect to muriatic acid by the experiments and 

 reasoning already advanced, when speaking of that substance, 

 in the subdivision respecting primary and secondary results 

 (758, &c). 



787. I consider the law as established also with regard to 

 hydriodic acid by the experiments and considerations already 

 advanced in the preceding division of this series of Researches 

 (767. 768.). 



788. Without speaking with the same confidence, yet from 

 the experiments described, and many others not described, 

 relating to hydro-fluoric, hydro-cyanic, ferro-cyanic, and 

 sulpho-cyanic acids (770. 77 i. 772.), and from the close ana- 

 logy which holds between these bodies and the hydro-acids 

 of chlorine, iodine, bromine, &c, 1 consider these also as 

 coming under subjection to the law, and assisting to prove its 

 truth. 



789. In the preceding cases, except the first, the water is 

 believed to be inactive ; but to avoid any ambiguity arising 

 from its presence, I sought for substances from which it should 

 be absent altogether; and, taking advantage of the law of 

 conduction already developed (380. &c), soon found abund- 

 ance, amongst which protochloride of tin was first subjected 

 to decomposition in the following manner. A piece of platina 

 wire had one extremity coiled up into a small knob, and 

 having been carefully weighed, was sealed hermetically into a 

 piece of bottle-glass tube, so that the knob should be at the 

 bottom of the tube within (fig. 13.). The tube was suspended 

 by a piece of platina wire, so that the heat of a spirit-lamp 

 could be applied to it. Recently fused proto-chloride of tin 

 was introduced in sufficient quantity to occupy, when melted, 

 about one half of the tube ; the wire of the tube was connected 

 with a volta-electrometer (711.), which was itself connected 

 with the negative end of a voltaic battery ; and a platina wire 

 connected with the positive end of the same battery was 

 dipped into the fused chloride in the tube ; being, however, 

 so bent, that it could not by any shake of the hand or ap- 

 paratus touch the negative electrode at the bottom of the ves- 

 sel. The whole arrangement is delineated fig. 14. 



790. Under these circumstances the chloride of tin was 

 decomposed : the chlorine evolved at the positive electrode 

 formed bichloride of tin (779.), which passed away in fumes, 



