2*98 VOLTAIC BATTERY. SECT. XXIX. 



It was shown by Grottlrus that the transmission of Voltaic elec- 

 tricity through liquids consists of a series of chemical affinities 

 acting indefinite directions ; and Mr. Grove, from an examination 

 of its action on the various kinds of matter, has come to the same 

 conclusion. Indeed it is now the generally received opinion that 

 a current of electricity is merely a continuous transmission of 

 chemical affinity from particle to particle of the substance through 

 which it is passing, and consequently that it is a continuous 

 transmission of force. As the Voltaic battery has become one of 

 the most important engines of physical research, some account 

 of its present condition may not be out of place. 



The disturbance of electric equilibrium, and a development of 

 electricity, invariably accompany the chemical action of a fluid on 

 metallic substances, and the electricity is most plentiful when 

 that action occasions oxidation. Metals vary in the quantity of 

 electricity afforded by their combination with oxygen. But the 

 greatest abundance is developed by the oxidation of zinc by weak 

 sulphuric acid. And, in conformity with the law that one kind of 

 electricity cannot be evolved without an equal quantity of the 

 other being brought into activity, it is found that the acid is 

 positively, and the zinc negatively electric. It-has not yet been 

 ascertained why equilibrium is not restored by the contact of 

 these two substances, which are both conductors, and in opposite 

 electrical states. However, the electrical and chemical changes 

 are so connected, that, unless equilibrium be restored, the action 

 of the acid will go on languidly, or stop as soon as a certain 

 quantity of electricity is accumulated in it. Equilibrium, never- 

 theless, will be restored, and the action of the acid will be con- 

 tinuous, if a plate of copper be placed in contact with the zinc, 

 both being immersed in the fluid ; for the copper, not being 

 acted upon by the acid, will serve as a conductor to convey the 

 positive electricity from the acid to the zinc, and will at every 

 instant restore the equilibrium, and then the oxidation of the 

 zinc will go on rapidly. Thus three substances are concerned in 

 forming a Voltaic circuit, but it is indispensable that one of them 

 should be a fluid. The electricity so obtained will be very 

 feeble in overcoming resistances offered by imperfect conductors 

 interposed in the circuit, or by very long wires, but it may be 

 augmented by increasing the number of plates. In the common 

 Voltaic battery, the electricity which the fluid has acquired from 



