Mr. J. Napier on Electrical Eudosmose. 1 1 



The object of this paper is not to define the cause, but to 

 point out the different conditions of electrical eudosmose, and 

 the important part it plays in electro-chemical investigation. 



The conditions under which electrical endosmose are ob- 

 served, are, that the two metals constituting a battery, or the 

 two electrodes of a battery, be placed in separate vessels or 

 divisions of the same vessel ; one of the vessels, or partition, 

 being composed of a material sufficiently close in texture to 

 prevent the mixture of the two liquids, and porous enough to 

 allow the electricity to permeate through it. The substances 

 generally used are bladder, parchment, unglazed porcelain, 

 &c. The last is what I have generally used in the experi- 

 ments to be detailed. 



The general effects of electrical endosmose are, a portion 

 of the positive solution passes along with the electric current 

 into the negative solution, not by electrolytic action, as has 

 been generally supposed, but by endosmotic action ; and this 

 endosmotic current is confined to the direct influence of the 

 electric current, or facing the metals composing the electrodes 

 or battery. There are some circumstances in which the posi- 

 tive solution gains in quantity, making an apparent current 

 contrary to the electrical ; these will be referred to as we 

 proceed. 



Electrical endosmose manifests itself in two ways, or rather 

 is of two kinds, which may be distinguished as the measurable 

 and the immeasurable, the former being the result of the trans- 

 fer of water from one cell to another, the latter of a salt or 

 acid held in solution, and which is being decomposed ; this 

 may take place to an extent equal to the whole salt held in 

 solution in the positive cell without the quantity of the two 

 solutions being materially altered ; and that this transfer is 

 from endosmose will be best illustrated by detailing a few 

 experiments, stating however that the investigation necessarily 

 involves a great number of experiments, the whole of which I 

 cannot detail, and the conclusions come to have been the 

 result of these. It may be stated here that the vessel or divi- 

 sion in which the positive electrode or metal is placed is termed 

 the positive solution, and the negative division the negative 

 solution. 



I. 20 ounces of water, in which were dissolved 500 grains 

 of sulphate of copper, were made the positive solution, and 

 other 20 ounces of water, with 500 grains of sulphate of cop- 

 per, were made the negative solution. A copper electrode, 

 previously weighed, was put into each of these solutions and 

 connected with a Wollaston's battery of nine pairs, the current 



