108 ELECTRICITY. 



by drawing it gently through my hand. [The 

 Lecturer repeated the experiment of exciting 

 the shellac, and then removing the attractive 

 power by drawing it through his hand.] Again 

 you will see I can repeat this experiment with 

 another substance ; for if I take a glass rod and 

 rub it with a piece of silk covered with what 

 we call amalgam, look at the attraction which 

 it has, how it draws the ball towards it ; and 

 then, as before, by quietly rubbing it through 

 the hand, the attraction will be all removed 

 again to come back by friction with this silk. 



But now we come to another fact. I will 

 take this piece of shellac, and make it attractive 

 by friction; and remember that whenever we 

 get an attraction of gravity, chemical affinity, 

 adhesion, or electricity (as in this case), the 

 body which attracts is attracted also, and just 

 as much as that ball was attracted by the 

 shellac, the shellac was attracted by the ball. 

 Now I will suspend this piece of excited shellac 

 in a little paper stirrup, in this way (fig. 33), in 

 order to make it move easily, and I will take 

 another piece of shellac, and after rubbing it 

 with flannel, will bring them near together : 

 you will think that they ought to attract each 



