168 ELECTRICAL PROPERTIES OF SILK. 
the most remote, which always kept an electricity 
opposite to that of the plate. 
The following experiments were performed by 
Mr Nicholson, on an improved method of excita- 
tion, as well as the action of points, and the direc- 
tion of the fluid in positive and negative electricity. 
1. A glass cylinder was mounted, and a cushion 
applied with a silk flap, proceeding from the edge 
of the cushion over its surface, and thence half 
round the cylinder. The cylinder was then excited 
by applying an amalgamed leather in the usual 
manner. The electricity was received by a con- 
ductor, and passed off in sparks to Lane’s electro- 
meter. By the frequency of these sparks, or by the 
number of turns required to cause spontaneous ex- 
plosion of a jar, the strength of the excitation was 
poised: 
. The cushion was withdrawn about one ‘nigh 
Po the cylinder, and the excitation performed by 
the silk only. A stream of fire was seen between 
the cushion and the silk ; and much fewer sparks 
passed between the balls of the electrometer. 
3. A roll of dry silk was interposed, to prevent 
the stream from passing between the cushion and 
the silk. Very few sparks then appeared at the 
electrometer. 
4. A metallic rod, not insulated, was then inter- 
posed instead of the roll of silk, so as not to touch 
