Silk Manufacture. 239 



subsequent separation show contrary states of electricity, which 

 would again disappear on their being brought together. If after 

 having been made by friction to repel each other, they were 

 forced together upon such a rough surface, they would in a few 

 minutes be inutually attracted, the under one being vitreously and 

 the upper ribin resinously electrified. 



'If the two ribins were subjected to friction upon a rough sur- 

 face, they uniformly acquired contrary states of electricity, the 

 upper being resinously and the lower one vitreously affected, in 

 whatever manner they might be taken off. The same change 

 was instantaneously produced by the use of any pointed conduct- 

 or. If, for instance, the two ribins having been made to repel 

 each other, the point of a needle were drawn along the whole 

 length of one, it would cause both instantly to rush together. 

 The same means employed to effect a change of electricity in a 

 ribin already electrified would communicate electricity to the 

 other, which had not yet received excitement. An unelec- 

 trified ribin would become electrified if placed upon a rough 

 surface and an electrified ribin were put upon it, or if the one 

 were held parallel to the other and a pointed conductor were pre- 

 sented. 



' Upon a smooth surface, Mr. Cigna placed a ribin which was 

 not quite dry, and applied over it another that had been well dried 

 before the fire, when, after applying to them the usual friction 

 with the ivory rule, he found that, in whatever manner they were 

 removed from the surface, the upper one was always resinously 

 and the lower one vitreously electrified. Exactly the same re- 

 sults were produced if the ribins employed were black instead 

 of white. If any kind of skin, or if a piece of smooth glass, 

 were used in place of the ivory rule, the effect was exactly the 

 same ; but if a roll of sulphur were substituted, the ribins then 

 uniformly acquired the vitreously electric state: when rubbed 

 with paper, either gilt or not gilt, the effects were uncertain. If 

 the ribins w€re placed between folds of paper on a plane surface 

 and friction were then applied to them, both ribins acquired the 

 resinous electricity. When one ribin was black, and the other 

 white, the black generally acquired the resinous and the white the 

 vitreous state, whatever might have been their relative position, or 

 the manner of applying friction. 



' Mr. Cigna likewise observed, that when the texture of the 

 upper piece of silk was loose, yielding, or retiform, like that of a 

 stocking, so that its elasticity caused it to move up and down 

 with the corresponding movements of the rubber against the sur- 

 face of the lower ribin; and if the rubber employed were of such 



