136 THEORY OF GALVANISM. 



proportion to the oxidation of the metallic surface. 

 It satisfactorily explains the progressive increase in 

 the energy of the different parts of the instrument. 

 The first copper plate, in consequence of the elec- 

 tricity which it has acquired from the oxidated 

 part of the zinc, becomes positive, or, to use the nu- 

 merical illustration, is brought to the state of 110. 

 PLATE II. This state it communicates to the contiguous, 

 or second zinc plate, which also becomes 110. 

 The fluid oxidates the surface of the metal here, as 

 in the former case, but a larger quantity of elec- 

 tricity is liberated to the second copper plate, which 

 raises it to 120. According to the chemical hy- 

 pothesis, although one end of the pile becomes 

 highly positive, and is therefore disposed to com- 

 municate a portion of its redundant electricity to 

 the other end, yet this end may be considered as 

 only relatively negative, and there is no part of 

 the apparatus in a neutral state. There is no 

 tendency in any part of the apparatus to restore 

 the equilibrium of the electric fluid which is de- 

 stroyed by the oxidation of the metal. The essen- 

 tial effect is to increase the electricity of one end 

 of the apparatus, and therefore the more powerful 

 is the action of the fluid either in oxidating the 

 metals, or in conveying the electricity to the oppo- 

 site surface, the more powerful will be the effect of 

 the apparatus. This effect does not necessarily 

 depend upon the ends of the pile being united, be- 

 cause the essence of the operation consists in the 

 oxidation of one of the metals. It is, however, to 



