202 FRICTION AL ELECTRICITY. 



cord thoroughly, and with it repeat the experiment ; the 

 leaves diverge instantly. Balance a meter stick or common 

 lath upon a wine-glass. About an inch below one end of 

 the stick support a few bits of paper or gold leaf. To the 

 other end of the lath bring an electrified glass rod. The 

 bits of paper will be alternately attracted and repelled by 

 the stick. Continue these experiments with other sub- 

 stances until you are convinced that some substances 

 transmit electricity readily and that others do not. 

 Those that offer little resistance to the passage of elec- 

 tricity are called conductors ; those that offer great resist- 

 ance are called non-conductors or insulators. A conductor 

 supported by a non-conductor is said to be insulated. 



334. Electrics. Any substance, when insulated, 

 may be sensibly electrified ; but when an uninsulated 

 conductor is rubbed, the electricity escapes as fast as 

 it is developed. Thus we see that the old division of 

 bodies into electrics and non-electrics, or bodies that may 

 be electrified and those that cannot be electrified, is nothing 

 more than a division into conductors and non-conductors. 



(a ) Suspend a copper globe or other metal body by a silk thread 

 and strike it two or three times with a cat's skin or fox's brush. 

 Bring the gold-leaf electroscope near the globe. The leaves will 

 diverge. 



335. Theory of Electricity. According to one provi- 

 sional theory, electric action is due to two fluids, each self repulsive ; 



. both mutually attractive ( 308, 309). When these opposite fluids 

 (+ and ) are mixed in equal quantities, they neutralize each other 

 and afford no manifestations. All bodies in the natural or unelec- 

 trified condition are pervaded by large quantities of this neutral 

 fluid. By friction, chemical action and other means, this fluid may 

 be decomposed, its two constituents being torn asunder. One fluid 

 clings by preference to the rubber ; the other to the body rubbed. 



