166 ELECTRICAL PROPERTIES OF SILK, © 
was of such a nature as could communicate but 
little electricity to glass, the electricity which the 
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 always 
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 
