160 ELECTRICAL PROPERTIES OF SILK. 



lized stones, all resinous compounds, and all dryo 

 substances, such as silk, hair, wool, paper, &c. 



Silk was first discovered to be an electric by Mr 

 Gray, in the manner we have already related ; but! 

 as it was by no means remarkable for emitting 

 sparks, which most commonly engages the atten- 

 tion, its electric virtues were almost entirely over- 

 looked till the year 1759. At that time Mr 

 Symmer presented to the Royal Society some pa- 

 pers, containing a number of very curious experi- 

 ments made with silk stockings, in substance as 

 follows : 



He had been accustomed to wear two pairs of 

 silk stockings, a black and a white. When these 

 were put off both together, no signs of electricity 

 appeared ; but on pulling off the black ones from 

 the white, he heard a snapping or crackling noise, 

 and in the dark perceived sparks of fire between 

 them. To produce this and the following appear- 

 ances in great perfection, it was only necessary to 

 draw his hand several times backward and forward 

 over his leg with his stockings upon it. 



When the stockings were separated, and held at 

 a distance from each other, both of them appeared 

 to be highly excited ; the white stocking positively, 

 and the black negatively. While they were kept* 

 at a distance from each other, both of them appeared 

 inflated, to such a degree, that they exhibited the. 

 entire shape of the leg. When two black or twd- 



