368 NINETEENTH CENTURY. ft. hi. 



good conductor, so that the current passes readily along it. 

 Thus, ice being a bad conductor, the slightest film of ice 

 interposed between the water and the electric wires will pre- 

 vent the current from setting free the oxygen and hydrogen ; 

 and ether and alcohol cannot be decomposed at all by elec- 

 tricity, because they will not conduct the current. 



He also showed that the electric current itself does not 

 depend upon any effect which the two metals have directly 

 upon each other, as Volta thought, but is caused by the 

 chemical action going on between the zinc and the water. 

 Thus, if you put some zinc in sulphuric acid and water, the 

 zinc pulls the water to pieces, and hydrogen gas comes bub- 

 bling off, but if you coat the zinc with mercury, hydrogen 

 will no longer come off, and no action will take place till 

 you put another metal in the water, as for example a piece 

 of copper and connect the two metals by a wire. Then the 

 hydrogen bubbles off again, but this time it does not come 

 off the zinc, but off the copper. The force which overcomes 

 the chemical attraction in the water has been made to travel 

 across the vessel from one metal to the other, and this 

 journey may be made as long a one as you choose, and 

 may even be continued for hundreds of miles if only the 

 current has some means of finding its way home to the first 

 metal at last. 



Now all this is a modified result of the chemical action 

 of the zinc and acid water upon each other; as Faraday 

 proved in a most beautiful way by showing that the power 

 of the electric current to decompose water in another vessel 

 depends entirely upon the violence of the action going on 

 between these two elements of the battery. If the battery 

 is weak, the water in which the ends of the wires are dipped 

 is decomposed slowly ; if the battery is strong, the bubblf^s 



