WINTER'S ELECTRICAL MACHINE. 599 



When the machine is worked while neither conduc- 

 'tor nor rubbers are in communication with the ground, 

 the sparks drawn from the machine become gradually 

 weaker, and even cease altogether. This is because 

 friction does not create new electricity, but merely causes 

 a separation of the two opposite kinds previously com- 

 bined; there is, therefore, at each turn of the machine 

 exactly as much positive electricity developed on the 

 plate as there is negative on the rubbers, and if the 

 rubbers are insulated they soon receive a charge of 

 negative electricity which it is impossible to exceed, 

 when the tendency of the opposed electricities to re- 

 unite is equal to the power of friction to separate them. 

 It follows that a continued succession of sparks can only 

 be obtained from either conductor or rubbers, if the elec- 

 tricity of the opposite kind is conducted away* When 

 the rubbers communicate with the ground, the negative 

 electricity disappears as fast as it is generated, and the 

 positive of the plate remains to act by induction on the 

 conductor in the manner already stated. Were the 

 rubbers insulated and no sparks drawn from them, all 

 development of positive electricity on the plate would 

 obviously cease immediately, but in reality there is con- 

 stantly some loss of electricity going on from the rubbers 

 in consequence of the vicinity of the wooden supports. 



If none of the quantity of electricity in the conductor 

 is withdrawn, it reaches a point of maximum charge, 

 at which negative electricity is no longer dispersed at 

 the row of points. The consequence is that the plate 

 no longer becomes neutral, that its positive charge 

 cannot be augmented by friction, and that no further 

 negative electricity can be developed. 



