ELECTRICITY. 



ELECTRICITY is that affection of matter or mode of force 

 which most distinctly and beautifully brings into relation 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 trans- 

 mitted 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 \\smodus agendi : the early theo- 

 ries 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 un- 

 supported by many who have attentively studied electrical 

 phenomena, in viewing them as resulting, not from the action 

 of a fluid or fluids, but as a molecular polarisation of ordinary 

 matter, or as matter acting by attraction and repulsion in a 

 definite direction. Thus, the transmission of the voltaic cur- 

 rent 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 be- 

 tween the poles or electrodes of a voltaic battery, a molecule 

 of oxygen is supposed to be displaced by the exalted attrac- 

 tion of the neighbouring electrode ; the hydrogen liberated 

 by this displacement unites with the oxygen of the conti- 

 guous molecule of water ; this in turn liberates its hydrogen, 

 and so on ; the current being nothing else than this molecular 

 transmission of chemical affinity. 



There is strong reason for believing that, with some ex- 

 ceptions, such as fused metals, liquids do not conduct elec- 

 tricity without undergoing decomposition ; for even in those 



