178 



HOW WE PRODUCE ELECTRICITY 



Current Electricity. If we rub wax rapidly with a dry 

 piece of woolen cloth, we can electrify it. The wax is 

 then said to be charged with electricity. A charged body 

 such as this is one in which electricity is at rest. To be 

 sure, the amount in the wax is very, very small, but if we 

 were to connect two oppositely charged bodies, negative 

 and positive, with a good conductor, such as a metal wire, 

 electricity would flow for just an instant from one body 

 to the other. Electricity in motion, as this is, is called 

 current electricity, and this means nothing more than a 

 flow of electrons. This is the kind of electricity which 

 we use in ringing our doorbells, in running our motors, 

 and in lighting our homes. 



Electric Cells. You may have heard the terms "dry 

 cell" and "wet cell," and doubtless some of you have 



seen them in your 

 .pitch homes, as these 

 5anct two kinds of cells 

 are used to ring 

 electric doorbells. 

 The wet cell is 

 made by nearly 

 filling a quart jar 

 with a saturated 

 solution of ammo- 

 nium chloride. In 

 this jar a large 

 carbon plate and 

 a zinc rod are 

 suspended side by 

 side, but not touching each other. When the ends or 

 poles of these elements are joined with a wire electricity 

 results through the release of chemical energy. The zinc 

 rod and the ammonium chloride are gradually destroyed 

 and must be replaced from time to time. 



mixture 



In both the wet cell and the dry cell it is the chemical 



action between the zinc and ammonium chloride that 



produces the electric current. Why is the dry cell used 



more than the wet cell ? 



