ON ELECTRICITY IN EQUILIBRIUM, 665 



rest when the quantities of redundant fluid are nearly equal ii^ both spheres, 

 and consequently when the density is greater in the smaller. And for a simi- 

 lar reason, in bodies of irregular forms, the fluid is always most accumulated 

 in the smallest parts; and when a conducting substance is pointed, the fluid 

 becomes so dense at its extremity, as easily to overcome the forces which 

 tend to retain it in its situation. (Plate XXXIX. Tig. 551.) 



In this distribution we find a very characteristic difference between the 

 pressure of the electric fluid and the common hydrostatic pressure of liquids 

 or of simple elastic fluids; for these exert on every surface similarly situated a 

 pressure proportionate to its magnitude; but the electric fluid exerts a pres- 

 sure on small and angular surfaces greater, in proportion to their magnitudes, 

 than the pressure on larger parts: so that if the electric fluid were in general 

 confined to its situation by the pressure of the atmosphere, that pressure 

 might easily -be too weak to oppose its escape from any prominent points. It 

 does not appear, however, that this pressure is the only cause which prevents 

 the escape of the electric fluid ; nor is it certain that this fluid can pass 

 through a perfect vacuum, although it has not yet been proved, that a body 

 placed in a vacuum is perfectly insulated. Whatever the resistance may be, 

 which prevents the dissipation of electricity, it is always the more easily over- 

 come, as the electrified substance is more pointed, and as the point is more 

 prominent; and even the presence of dust is often unfavourable to the suc- 

 cess of electrical experiments, on account of the great number of pointed ter- 

 . minations which it affords. 



The general effect of electrified bodies on each other, if their bujk is sniall 

 in comparison with their distance, is, that they are mutually repelled when in 

 similar states of electricity, and attracted when in dissimilar states. This is a 

 consequence immediately deducible from the mutual attraction of redundant 

 matter and redundant fluid, and from the repulsion supposed to exist between 

 any two portions either of nratter or of fluid, and it may also easily be con- 

 firmed by experimental proof. A neutral body, if it were a perfect noncon- 

 ductor, would not be affected either way by the neighbourhood of.an electri- 

 fied body : for while the whole matter contained in it remains barely saturated 

 with the electric fluid, the attractions and repulsions balance each other, Eut 

 in general, a neutral body appears to be attracted by an electrified body, on 



