166 ELECTRICAL PROPERTIES OF SILK. 



was of such a nature as could communicate bull 

 little electricity to glass, the electricity which th| 

 upper piece of silk acquired did not depend upon! 

 the rubber, but upon the body on which it was! 

 laid. In this case, the black was always negative! 

 and the white positive. But when the silk was 

 hard, rigid, and of a close texture, and the rubber 

 of such a nature as would have imparted a great 

 degree of electricity to glass, the electricity of the 

 upper piece depended on the rubber. Thus, a 

 white silk stocking, rubbed with gilt paper upon 

 glass, became negatively, and the glass positively 

 electrified. But if a piece of silk of a firmer tex- 

 ture was laid upon a plate of glass, it was al/c<i//s 

 electrified positively, and the glass negatively, if it 

 was rubbed with sulphur, and for the most part if 

 it was rubbed with gilt paper. 



If an electrified riband was brought near an 

 insulated plate of lead, it was attracted, but very 

 feebly. On bringing the finger near the lead, a 

 spark was observed between them, the riband was 

 vigorously attracted, and both together showed no 

 signs of electricity. On the separation of the riband, 

 they were again electrified, and a spark was per- 

 ceived between the plate and the finger. 



When a number of ribands of the same colour 

 were laid upon a smooth conducting substance, and 

 the ruler was drawn over them, he found, that 

 when they were taken up singly, each of them gave 



