164 ELECTRICAL PROPERTIES OF SILK. 



the operation just now mentioned, they had 

 quired the negative electricity, if they were placed 

 not upon the smooth body on which they had beer 

 rubbed, but on a rough conducting substance, they 

 would, on their separation, show contrary electrici. 

 ties, which would again disappear on their being join, 

 ed together. If they had been made to repel eacl 

 other, and were afterwards forced together, anc 

 placed on the rough surface above mentioned, thej 

 would in a few minutes be mutually attracted 

 the lowermost being positively, and the uppermost 

 negatively electrified. 



If the two white ribands received their frictior 

 upon the rough surface, they always acquired con- 

 trary electricities. The upper one was negatively 

 and the lower one positively electrified, in what- 

 ever manner they were taken off. The same change 

 was instantaneously done by any pointed conductors 

 If two ribands, for instance, were made to repel 

 and the point of a needle drawn opposite to one o 

 them along its whole length, they would imme- 

 diately rush together. 



The same means which produced a change (M 

 electricity in a riband already electrified, would 

 communicate electricity to one which had not as yet 

 received it, viz. laying the unelectrified riband up- 

 on a rough surface, and putting the other upon it, 

 or by holding it parallel to an electrified riband, 

 and presenting a pointed conductor to it. He 



