VOL. LI.] i'HILOSOPHICAL TRANSACTJOXS. 407 



the stockings continue longer fit for these experiments : for, like other electrical 

 apparatuses, they must be kept clean, and free from all extraneous matter ; and 

 are therefore most to be depended on when new, or when newly washed. 



After being a little aired at the fire, when the black silk is drawn single on the 

 hand, a crackling noise is heard; and in the dark sparks of fire may be per- 

 ceived, as passing between the hand and the stocking: while it is drawn back- 

 wards and forwards the crackling continues, and is most considerable on the sepa- 

 ration of the stocking from the hand. Thus it appears, that black silk is highly 

 susceptible of electricity ; that it is produced almost instantaneously, or at least 

 with very little friction; that most of it escapes, while the stocking is yet on the 

 hand ; and that, on the total separation, very little remains. This is similar to what 

 happens with the glass tube, when the hand, after passing along it in one direc- 

 tion, repasses it in the other. But still the electricity that the stocking retains, 

 after it is separated from the hand, is considerable enough to attract or repel 

 little light bodies at the distance of 1 or 2 feet: some degree of inflation in the 

 stocking is likewise perceivable; and when a non-electric is brought near it, a 

 crackling is heard, and in the dark sparks may be seen. If 2 black stockings 

 be drawn on the hand at a time, the appearances are much the same as before ; 

 only that the stockings, when taken off and separated, give smaller proofs of 

 electricity, than if each of them had been single on the hand. 



White silk differs much in electricity from black silk. When the white 

 stocking is drawn separately on the hand, no crackling is heard, nor sparks of 

 fire seen in the dark, though it be pulled backward and forward ever so often: 

 when another white stocking is drawn on above it, nothing more appears: and, 

 when separated from the hand, neither of them discovers any signs of electricity, 

 excepting that, when brought within a few inches of Canton's pocket electro- 

 meter, they attract and repel the balls a little. 



If, instead of 2 white or 2 black stockings, one white, and over that a black 

 stocking be drawn on the hand, they discover not the least signs of electricity 

 while they continue on the hand, even though they should be drawn backward 

 and forward on it several times; nor, when taken together from the hand, and 

 presented to the electrometer, do they appear to have acquired any more than a 

 very small degree of electricity. They must be brought within the distance of 

 a foot, nay, sometimes of a few inches, before they have any effect on the balls 

 but the moment they are separated, they are found to be both of them highly 

 electrified, the white positively, and the black negatively. The circumstances 

 that appear the most to merit observation, are as follow: 



1°. — When the electrometer is placed on a non-electric, and the black stocking 

 is presented to it at the distance of 3, 4, or 5 feet, according as it happens to be 

 more or less powerfully electrified, the balls begin to be visibly attracted, and 



