FRICT10NAL ELECTRICITY. 205 



tricity opposite in kind to that of C. Thus a body may be 

 charged by induction with no loss to the inducing body. 



340. Successive Induction. If a series of insu- 

 lated conductors be placed in line as shown in Fig. 142, 

 and a positively electrified body be brought near, each 

 conductor will be polarized. The first will be polarized by 

 the influence of the -f of C\ the second by the influence 

 of the + of M, and so on. 



(a.} Either electricity from M or N may be carried by a small 

 insulated body, called a proof -plane (Fig. 158), to the electroscope, 

 there tested and found to be as represented in the figure. If the 

 conductors M and .ZVbe now placed in actual contact, the + of both 

 will be repelled by G to the furtherest extremity of W and the 

 of both attracted to the opposite end of M, near to G. 

 C 





FIG. 142. 



(b.) It is very plain that any body may be looked upon as a collec- 

 tion of many parallel series of such conductors, each molecule 

 representing a conductor. Thus each molecule may be polarized, 

 + on one side and on the other. If the body in question be a 

 good conductor of electricity, this polarization of the molecules is only 

 for an instant. The two electricities pass from molecule to mole- 

 cule and accumulate at opposite ends of the body. The body is 

 then polarized, but not the molecules of the body. On the other 

 hand, good insulators resist this tendency to transmit the electrici- 

 ties from molecule to molecule and are able to maintain a high 

 degree of molecular polarization for a great length of time. In 



