276 SCIENCE OF COMMON THINGS. 



Electrified and non-electrified bodies. 



17*93 When a substance, by friction or by any other means, acquires 

 the property of attracting other bodies, in what state is it said to be? 



It is said to be electrified^ or electrically excited / and 

 its motion towards other bodies, or of other bodies to- 

 wards it, is ascribed to a force called electric attraction. 



17*09 Does an electrified body exercise any other influence than an, 

 attractive onef 



It does ; for it will be found that light substances, 

 after touching the electrified body, will recede from it 

 just as actively as they approached it before contact. 

 This is termed electric repulsion. 



Thus, if we take a dry glass rod, rub it 

 well with silk, and present it to a light pith 

 ball, or feather, suspended from a support 

 by a silk thread, the ball or feather will be 

 attracted towards the glass, as seen at G, 

 Fig. 81. After it has adhered to it a mo- 

 ment, it will fly off, or be repelled, as P' from 

 G'. The same will happen if sealing-wax 

 be rubbed with dry flannel, and a like ex- 

 Fig. 81. periment made ; but with this remarkable 

 difference, that when the glass repels the 



ball, the sealing-wax attracts it, and when the wax repels, the glass will 

 attract. These phenomena are examples of electrical attraction and 

 repulsion. 



1800 What is a non-electrified body f 



One that holds its own natural quantity of electricity 

 undisturbed. 



1801 What happens when an electrified body touches one that is non- 

 electrified f 



The electricity contained in the former is transferred 

 in part to the latter. 



Thus, on touching the end of a suspended silk-thread with a piece of 

 excited wax, the silk will be excited, as will be shown by its moving 

 towards a book, piece of metal, or any other object placed near it. 



18OS Do all bodies conduct or allow electricity to pass through them 

 equally well? 



Although there is no substance that can entirely pre- 

 vent the passage of electricity, nor any that does not 

 oppose some resistance to its passage, yet it moves with 

 a much greater facility through a certain class of sub- 

 stances than through others. Those substances which 



