[ m ] 



XVII. On the unequal Decomposition of Electrolytes, and the 

 Theory of Electrolysis. By Mr. James Napiek*. 



IN a paper which I submitted to the Society last session 

 upon this subject t» it was mentioned that the funda- 

 mental law laid down by electro-chemists, "That there can 

 be no inequality of decomposition in any part of an electro- 

 lyte," is not applicable under all circumstances, especially 

 when the negative element of the electrolyte can combine with 

 the positive electrode, there being under such circumstances 

 an increased tendency in the electrode to combine with the 

 electrolyte, which causes a greater amount of decomposition 

 or chemical action at the positive than at the negative elec- 

 trode. 



That the extra amount of decomposition at the positive 

 electrode is not the result of the ordinary solvent powers of 

 the electrolyte for the metal composing the electrode, was 

 shown by pieces of the same metal being put into the same 

 solutions as the electrolyte the same length of time as the 

 battery was in action, and which were in some cases not 

 affected, and in others only a small fraction of that which 

 had taken place at the positive electrode above what the 

 current of electricity passing accounted for ; showing that the 

 increased affinity between the elements of the electrolyte and 

 the electrode had its origin in some influence communicated 

 by the battery, and was not accounted for by the amount of 

 electricity passing, measured by the deposition of a metal 

 upon the negative electrode, and as experiments which were 

 being made showed, without any relation to that current. 



I had observed, while experimenting upon electrical endos- 

 mose, that there seemed some relation between the cause of 

 measurable endosmose and the phenomenon under considera- 

 tion : it became therefore probable that the element of an 

 electrolyte liberated at the negative pole, such as a de- 

 posited metal, might not be, as I had formerly thought, an 

 accurate measure of the whole electricity passing through 

 the solution under all circumstances, but that a feeble cur- 

 rent may be also passing, which may be sufficient to give a 

 greater disposition, if I may be allowed the term, to the solid 

 electrode to combine with the elements of the electrolyte, but 

 not of sufficient power to decompose all the particles of the 

 compound fluid through which it passes to the negative elec- 

 trode, the solution conducting it as a solid conductor would, or 

 rather, as appears from the results described in my paper on 



* Communicated by the Chemical Society; having been read January 

 5, 1846. 

 f See Phil. Mag. S. 3. vol. xxvi. p. 211. 



