IV. ELECTKICITY. 



"TT^LECTRICITY is that affection of matter or mode of 

 "j force which most distinctly and beautifully relates other 

 modes of force, and exhibits, to a great extent in a quantita- 

 tive form, its own relation with them, and their reciprocal 

 relations with it and with each other. From the manner 

 in which the peculiar force called electricity is seemingly 

 transmitted through certain bodies, such as metallic wires, 

 the term current is commonly used to denote its apparent 

 progress. It is very difficult to present to the mind any 

 theory which will give a definite conception of its modus 

 agendi: the early theories regard its phenomena as produced 

 either by a single fluid idio-repulsive, but attractive of all 

 matter, or else as produced by two fluids, each idio-repulsive 

 but attractive of the other. No substantive theory has been 

 proposed other than these two ; but although this is the case, 

 I think I shall not be unsupported by many who have atten- 

 tively studied electrical phenomena, in viewing them as re- 

 sulting, not from the action of a fluid or fluids, but as a mole- 

 cular polarisation of ordinary matter, or as matter acting by 

 attraction and repulsion in a definite direction. Thus, the 

 transmission of the voltaic current in liquids is viewed by 

 Grotthus as a series of chemical affinities acting in a definite 

 direction : for instance, in the electrolysis of water, i. e. its 

 decomposition when placed between the poles or electrodes 



