84 COKRELATION OF PHYSICAL FOKCE8. 



of a voltaic battery, a molecule of oxygen is supposed to be 

 displaced by the exalted attraction of the neighbouring elec- 

 trode ; the hydrogen liberated by this displacement unites 

 with the oxygen of the contiguous 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 

 extreme cases where a trifling effect of conduction is appar- 

 ently produced without the usual elimination of substances at 

 .the electrodes, the latter when detached from the circuit 

 show, by the counter-current which they are capable of pro- 

 ducing when immersed in a fresh liquid, that their superficial 

 state has been changed, doubtless by the determination to 

 the surfaces of minute layers of substances having opposite 

 chemical characters. The question whether or not a minute 

 conduction in liquids can take place unaccompanied by chemi- 

 cal action, has however been much agitated, and may be re- 

 garded as inter apices of the science. 



Assuming for the moment electrolysis to be the only 

 known electrical phenomenon, electricity would appear to con- 

 sist in transmitted chemical action. All the evidence we 

 have is, that a certain affection of matter or chemical change 

 takes place at certain distant points of space, the change at 

 one point having a definite relation to the change at the 

 other, and being capable of manifestation at any intermediate 

 points. 



If, now, the electrical effect called induction be examined, 

 the phenomena will be found equally opposed to the theory of 

 a fluid, and consistent with that of molecular polarisation. 

 When an electrified conductor is brought near another which 

 is not electrified, the latter becomes electrified by influence or 

 induction, as it is termed, the nearest parts of each of these 



