332 THE VOLTAIC BATTERY. [SECT. xxix. 



are concerned in forming a Voltaic circuit, but it is indis- 

 pensable that one of them should be a fluid. The elec- 

 tricity so obtained will be very feeble in overcoming resist- 

 ances offered by imperfect conductors interposed in the cir- 

 cuit, or by very long wires, but it may be augmented by in- 

 creasing the number of plates. In the common Voltaic bat- 

 tery, the electricity which the fluid has acquired from the 

 first plate of zinc, exposed to its action, is taken up by the 

 copper plate belonging to the second pair, and transferred to 

 the second zinc plate, with which it is connected. The second 

 plate of zinc, possessing equal powers, and acting in conform- 

 ity with the first, having thus acquired a larger portion of elec- 

 tricity than its natural share, communicates a larger quan- 

 tity to the fluid in the second cell. This increased quantity 

 is again transferred to the next pair of plates ; and thus every 

 succeeding alternation is productive of a further increase in 

 the quantity of the electricity developed. This action, how- 

 ever, would stop unless a vent were given to the accumu- 

 lated electricity, by establishing a communication between 

 the positive and negative poles of the battery by means of 

 wires attached to the extreme plate at each end. When the 

 wires are brought into contact, the Voltaic circuit is com- 

 pleted, the electricities meet and neutralize each other, pro- 

 ducing the shock and other electrical phenomena ; and then 

 the electric current continues to flow uninterruptedly in 

 the circuit, as long as the chemical action lasts. The stream 

 of positive electricity flows from the zinc to the copper. 

 The construction and power of the Voltaic battery has been 

 much improved of late years, but the most valuable recent 

 improvement is the constant battery of Professor Daniell. 

 In all batteries of the ordinary construction, the power, 

 however energetic at first, rapidly diminishes, and ulti- 

 mately becomes very feeble. Professor Daniell found that 

 this diminution of power is occasioned by the adhesion of the 

 evolved hydrogen to the surface of the copper, and to the 

 precipitation of the sulphate formed by the action of the acid 



