Chemical Theory of Electricity and Magnetism. 63 



quill across a dry wine-glass, and another across another wine-glass; 

 let the ends of them touch each other, as they lie in a horizontal 

 line; call them X and Y; approach a rubbed glass-tube near the 

 external end of the skewer X, but not so as to touch it; then separate 

 the two skewers by removing the wine-glasses further from each 

 other; and lastly, withdraw the rubbed glass-tube, and the skewer X 

 will now be found to possess resinous electricity, which has been 

 generally called negative or minus electricity; and the skewer Y will 

 be found to possess vitreous, or what is generally termed positive or 

 plus electricity. 



The same phenomenon will occur if rubbed sealing wax be applied 

 near to, but not in contact with, the skewer X, as the skewer X will 

 then be left with an atmosphere of vitreous ether, and the skewer Y 

 with one of resinous ether. These experiments also evince the exist- 

 ence of two electric fluids, as they cannot be understood from an idea 

 of one being a greater or less quantity of the same material; as a 

 vacuum of electric ether, brought near to one end of the skewer, can- 

 not be conceived so to attract the ether as to produce a vacuum at 

 the other end. 



In this experiment the electric atmospheres, which are nearly of 

 similar kinds, do not seem to touch, as there may remain a thin plate 

 of air between them, in the same manner as small globules of mercury 

 may be pressed together so as to compress each other, long before 

 they intermix; or as plates of lead or brass require strongly to be 

 pressed together before they acquire the attraction of cohesion; that 

 is, before they come into real contact. 



2. It is probable, that all bodies are more or less perfect con- 

 ductors, as they have less or more of either of the electric ethers com- 

 bined with them; as mentioned in Preliminary Proposition, No. VI. 

 as they may then less resist the passage of either of the ethers through 

 them. Whence some conducting bodies admit the junction of these 

 spontaneous electric atmospheres, in which the proportions or quan- 

 tities of the two ethers are not very different, with greater facility 

 than others. 



Thus in the common experiments, where the vitreous or resinous 

 ether is accumulated by art, metallic bodies have been esteemed 



