Chemical Theory of Electricity and Magnetism. 55 



When sealing wax or sulphur is rubbed by a cushion, exactly the 

 same circumstance occurs, but with the different ethers; as the resi- 

 nous ether of the spontaneous atmosphere of the cushion, Avhen it is 

 pressed within the spontaneous atmosphere of the sealing wax, is at- 

 tracted by the solid vitreous ether, which is combined with it; and 

 at the same time the vitreous ether of the cushion is repelled by it; 

 and hence an atmosphere of resinous ether alone exists between the 

 sealing wax and the cushion thus pressed together. It is nevertheless 

 possible, that friction on both sealing wax and glass may add some, 

 facility to the accumulations of their opposite ethers by the warmth 

 which it occasions. As most electric machines succeed best after being 

 warmed, I think even in dry frosty seasons. 



Though when a cushion is applied to a smooth surfaced glass, so 

 as to intermix their electric atmospheres, the vitreous ether of the 

 cushion is attracted by the resinous ether combined with the glass; but 

 does not intermix with it, but only adheres to it : and as the glass 

 turns round, the vitreous electric atmosphere stands on the solid 

 resinous electric ether combined with the glass; and is taken away by 

 the metallic points of the prime conductor. 



Yet if the surface of the glass be roughened by scratching it with 

 a diamond or with hard sand, a new event occurs; which is, that the 

 vitreous ether attracted from the cushion by the resinous ether com- 

 bined with the glass becomes adhesive to it; and stands upon the 

 roughened glass, and will not quit the glass to go to the prime con- 

 ductor; whence the surface of the glass having a vitreous electric 

 atmosphere united, as it were, to its inequalities, becomes similar to 

 resin; and will now attract resinous electric ether, like a stick of 

 sealing-wax, without combining with it. Whence this curious and 

 otherwise unintelligible phenomenon, that smooth surfaced glass will 

 give vitreous electric ether to an insulated conductor, and glass with 

 a roughened surface will give resinous ether to it. 



V. Accumulation of electric ethers by vicinity. 



Though the contact of a cushion on the whirling glass is the easiest 

 method yet in use for the accumulation of the vitreous electric ether 



