VOL. LI.] PHILOSOPHICAL TRANSACTIONS. 40y 



into an agitation that is not unentertaining, and makes them catch each at that 

 of its opposite colour, at agreater distance than one would expect. When al- 

 lowed to come together, they all unite in one mass: when separated, they re- 

 sume their former appearance, and admit of the repetition of the experiment as 

 often as you please; till their electricity, gradually wasting, stands in need of being 

 recruited. 



50. — ^When they are separated from each other, they lose their power very 

 soon, much as the excited tube does; but when they are together, they retain it 

 for an hour or two, and longer, when the air is in a state favourable for electri- 

 city. While they are asunder, and any non-electric is brought near them ; if 

 that non-electric is of a broad surface, it is with difficulty they are discharged of 

 their electricity ; but if the point of any, especially of a metallic, body, be pre- 

 sented, they are instantaneously deprived of their electrical virtue: but if they 

 be in conjunction together, they retain their electricity with so much obstinacy, 

 that even the sharpest point of metal cannot deprive them of it. In this, and in 

 some other respects, there appears to be such a resemblance between the Leyden 

 phial, or the electrical pane of glass, and the black stocking in conjunction with 

 the white, especially when the one is within the other, that Mr. S. considers 

 them both in the same light. In both cases, the positive electricity is on the one 

 side, and the negative on the other; and the stockings, as well as the phial, and 

 the pane of glass, are at once electrified positively and negatively. In both 

 cases there is an accumulation of electricity, and a retention of it, far beyond 

 what is to be met with in a simple body, electric or non-electric. There is 

 however a very remarkable difference between them in two respects. In the 

 phial, and in the pane of glass, an explosion is always obtained by carrying on a 

 communication between the two sides by the interposition of a non-electric; but 

 in the case of the black stocking and the white, he never could procure an explo- 

 sion, nor so much as a speedy discharge, while the one was within the other. 

 On the other hand, the phial and the pane of glass afford no opportunity of sepa- 

 rating the positive from the negative electricity, so as to show them entire and 

 distinct from each other; whereas we need only pull the stockings asunder, and 

 then in the white we find the positive, and in the black the negative electricity. 



go. — ^When the stockings are separated, and in the dark, on presenting to 

 them the point of one's figure, or any small metallic body, rounded at the end, 

 they exhibit the appearance of electrical fire or light, according to the negative 

 or positive state of the stocking the object is presented to. With the black, at 

 the distance of 2 or 3 inches, there appears to dart from the end of the finger a 

 sprig or pencil, as it were, of fiery sparks, which dilates in its progress, and 

 strikes against the surface of the stocking: at the same time a crackling or snap- 

 ping noise is heard. When the first discharge is made, on presenting the finger 



VOL. XI. 3 G 



