140 THEORETICAL OBSERVATIONS. 



the ordinary chemical affinity of the bodies present. The body under 

 decomposition (say sulphate of copper), may be considered as a 

 mass of acting particles, all those which are included in the course 

 of the electric current contributing to the final effect; and it is 

 because the ordinary chemical affinity is relieved, weakened, or 

 partly neutralized by the influence of the electric current in one 

 direction parallel to the course of the latter, and strengthened or 

 added to in the opposite direction, that the combining particles 

 have a tendency to pass in opposite courses. 



" In this view the effect is considered as essentially dependent upon 

 the mutual chemical affinity of the particles of opposite \ kinds. 



Particles aa could not be transferred 

 or travel fr m one P ole N, towards 



the other pole P, unless they found 

 48 particles of the opposite kind bb, 



ready to pass in the contrary direc- 



tion, for it is by virtue of their increased affinity for those particles, 

 combined with their diminished affinity for such as are behind them 

 in their course, that they are urged forward. 



" I conceive the effects to arise from forces which are internal, 

 relative to the matter under decomposition, and not external, as they 

 might be considered, if directly dependent upon the poles. I sup- 

 pose that the effects are due to a modification by the electric current 

 of the chemical affinity of the particles, through or by which that 

 current is passing, giving them the power of acting more forcibly 

 in one direction than in another, and consequently making them 

 travel by a series of successive decompositions, in opposite directions, 

 and finally causing their expulsion or exclusion at the boundaries of 

 the body under decomposition, in the direction of the current, and 

 that in larger or smaller quantities, according as the current is more 

 or less powerful." 1 



In the above figure, the particles aa may be termed copper Cu, 

 and the particles bb, sulphuric acid SO 4 , which will enable us to 

 follow the comparison of the different views. 



Graham's Theory of Electrolysis. Professor Graham supposes 



that the compound particles, such as sulphate of copper, possess 

 polarity, so that the particles in the battery 

 or decomposition cell will stand in relation 

 to ea h ot her in a polar chain, as in fig. 49. 

 He then represents electrotyping by the 

 porous cell system, as follows : 



" The liquids on either side of the porous division may also be 

 different, provided they have both a polar molecule. Thus, in 



1 Faraday's Experimental Researches, vol. i. paragraphs 518, 519, 524. 



