SOME CHEMISTRY OF EVERYDAY LIFE 187 



action. The electrolyte will then remain at the same 

 strength of solution all the time, and the metal from the 

 anode will gradually accumulate at the cathode in a pure 

 state. Chemically pure metals, such as copper, are prepared 

 or " refined" in great quantity for the industries by electro- 

 lytic action. 



When the binding posts of the piece of apparatus known as 

 a "simple cell" are connected by a wire, and the two metal 

 strips as terminals of this wire are put down into the acid 

 solution of the cell as an electrolyte, the two plates of the cell 

 may be considered as electrodes. This is true of other kinds 

 of cells. The current set up in such a closed circuit is sup- 

 posed to enter the cell from the external circuit by the zinc 

 plate as anode, and to leave the cell from the copper plate as 

 cathode. 



It is interesting to note that storage batteries such as are 

 used in electric motor cars are " charged" by electrolytic 

 action. Chemical changes are made upon the plates of the 

 storage cells by the hydrogen and oxygen set free by the 

 passing current. During the charging process these plates 

 are the electrodes of the " primary current." When these 

 chemical changes have been completed, the storage battery 

 is " charged." The connections with the primary circuit 

 may then be broken, and the storage battery is now in its 

 turn capable of sustaining a current to run the car so long as 

 a reversed chemical action continues. When the plates 

 have been restored to their original condition chemically, 

 the storage battery must be charged anew. The "gassing" 

 of the storage cells at the completion of the charging process 

 is but the escape of oxygen and hydrogen gases formed by 

 electrolysis, and not longer used in chemical changes on the 

 plates of the cells. 



The marvelous changes that have been wrought by the 

 application of electricity in the industries is well illustrated 



