466 PHILOSOPHICAL TRANSACTIONS. [anNO 1778. 



though at first sight extraordinary, could be explained by the same principles 

 which were already received by almost every philosopher. 



But before proceeding to my intended explanation of the more obvious phe- 

 nomena of the electrophorus, I must beg leave to set down some constant laws, 

 which nature observes in the various motions of the electric fluid, and to which 

 electricians do not seem to give a suflicient attention. 1 . The electric fluid exists 

 in all substances, in a certain quantity, which is natural to them. 2. The elec- 

 tric fluid is repulsive of itself, that is, each particle of electric fluid tends to 

 recede as far from another particle of the same fluid as it can. 3. The state of 

 electricity of a body, is that in which it has acquired more electrical fluid than 

 the neighbouring bodies, or in which it has less of this fluid than the surround- 

 ing bodies. 4. In the first case, the electrical fluid tends to expand itself 

 through all bodies near it, which can by their nature receive it. In the 2d case, 

 the electrical fluid of all the surrounding bodies, finding less resistance towards a 

 body negatively electrified, or having lost a part of its natural share of electricity, 

 rushes towards that body, and tends to diffuse itself through it, and thus to 

 dispose itself in an equilibrium. 



5. The reason why the electric fluid, existing every where, seems to remain 

 inactive in the common state of nature, is, because all other bodies having their 

 ordinary share of this fluid, an equal pressure exists on ail sides. Thus, if all 

 the bodies on the earth were to acquire more or less of electric fluid at the same 

 time, in equal proportions, no electrical phenomena would be the consequence 

 of such a state ; because the pressure Leing every where equal, the repulsive 

 force of the electrical particles would be every where balanced. Thus two bodies, 

 both negatively or both positively electrified, will not give a spark to each other 

 they only recede more from each other, because the other surrounding bodies 

 are not in the same situation with them. This assertion seems to be illustrated 

 by Father Beccaria's electrical well (puteus electricus,) which is nothing but a 

 metal vessel electrified, in which two cork balls are suspended by silk threads ; 

 the balls do not show signs of electricity within the cavity of the vessel, because 

 the electric fluid presses equally on every side. 



6. All non-conducting bodies may acquire, on each part of their substance, 

 more or less of the electric fluid, as well as conducting bodies, at least to a cer- 

 tain proportion ; but they do not allow it to pass freely through their substance 

 or over their surfaces. 



7. All bodies whatever are susceptible of electricity, positive and negative in- 

 differently, either by exciting them by friction or any other way, or by bringing 

 them within the sphere of action of a body already electrical ; so that even 

 metals, the best conductors, may be as easily excited by friction, if insulated, as 



