THE SMALLEST WORKERS 



means could be found to induce the chlorine atom to 

 give up the surplus electron which from time to time it 

 carries. And this means is provided when two pieces of 

 metal of different kinds, united with a metal conductor, 

 are immersed in the liquid. Then it comes to pass that 

 the electrons associated with the chlorine atoms that 

 chance to lie in contact with one of these plates of metal, 

 find in this metal an avenue of escape. They rush off 

 eagerly along the metal and the connecting wire, and in 

 so doing establish a current which acts if we may 

 venture a graphic analogy from an allied field of physics 

 as a sort of suction, attracting other chlorine atoms 

 from the body of the liquid against the metal plate that 

 they also may discharge their electrons. In other words, 

 the electrical current passes through the liquid as well 

 as through the outside wire, thus completing the 

 circuit. 



According to this theory, then, the electrical energy 

 in evidence in the current from the voltaic cell, is drawn 

 from a store of potential energy in the atoms of matter 

 composing the liquid in the cell. In practice, as is well 

 known, the liquid used is one that affects one of the 

 metal poles more actively than the other, insuring 

 vigorous chemical activity. But the principle of atomic 

 and electrical dissociation just outlined is the one in- 

 volved, according to theory, in every voltaic cell, what- 

 ever the particular combination of metals and liquids 

 of which it is composed. It should be added, however, 

 that while we are thus supplied with a thinkable 

 explanation of the origin of this manifestation of 

 electrical energy, no explanation is forthcoming, here 



[167] 



