ELECTRICITY PRODUCED BY FRICTION. 



551 



ELECTRICITY AND MAGNETISM. 



A. Frictional Electricity. 



44. Electrical attraction and repulsion. Conductors 

 and Non-conductors. A small cork ball, from 6 to 10 mm 

 diameter, is attached to a linen or cotton thread, be- 

 tween 20 and 40 cm long, and suspended 

 from the retort stand or the wooden 

 frame shown in fig. 35, or a suitably bent 

 wire frame, as in fig. 3ol. When a stick 

 of sealing-wax previously rubbed with a 

 piece of flannel is held near to the cork 

 ball, the ball will be attracted by the 

 sealing-wax, and even adhere to it for a 

 short time. Ebonite, sulphur, and many 

 other bodies, when rubbed with a piece 

 of woollen cloth, manifest the same be- 

 haviour. A piece of writing-paper, well 

 dried 'before a fire, and brushed over a 



few times with a dry, warm cloth-brush, F IG . 301. (uv.proj. 

 attracts the cork ball strongly when 

 brought near to it. Glass will exhibit the same attrac- 

 tion, but it must be rubbed either with silk or an 

 amalgam, that is, an alloy of mercury and other metals 

 spread over a piece of wool or leather. 



These bodies manifest thus, when rubbed, an attractive 



