EVOLUTION OF ELECTRICITY. Ill 



I have shaped into a cap for it and made dry. 

 I will put this shellac into the flannel, and here 

 comes out a very beautiful result. I will rub 

 this shellac and the flannel together (which 

 I can do by twisting the shellac round), and 

 leave them in contact ; and then, if I ask, by 

 bringing them near our indicator, what is the 

 attractive force ? it is nothing ! But if I take 

 them apart, and then ask what will they do 

 when they are separated, why the shellac is 

 strongly repelled, as it was before, but the cap 

 is strongly attractive ; and yet if I bring them 

 both together again, there is no attraction it 

 has all disappeared [the experiment was re- 

 peated]. Those two bodies therefore still con- 

 tain this attractive power when they were 

 parted it was evident to your senses that they 

 had it, though they do not attract when they 

 are together. 



This then is sufficient in the outset to give 

 you an idea of the nature of the force which we 

 call ELECTRICITY. There is no end to the things 

 from which you can evolve this power. When 

 you go home take a stick of sealing-wax I 

 have rather a large stick, but a smaller one will 

 do and make an indicator of this sort (fig. 35). 



