ON ELECTRICAL CHARGES AND DISCHARGES. O^J 



are, exhibit on their opposite surfaces electricities of oppo- 

 site kinds, as well as the assemblage resulting from them. 



Coulomb and Haiiy have been led to an analogous re- Coulomb and 



suit in their inquiries concerning magnetism, and the electri- "any infer the 

 ^ o 13 ' ^ ^ same if magne- 



city of the tourmaline, but they had not extended this idea to tism and the 



every charged insulating stratum. It appears however, that the^tourm^ 

 the modification of the heated tourmaline is not even a par- line. 

 ticular case of the general principle we have just admitted: 

 that this stone is not then simply a charged insulating body, 

 or a body interposed between two contrary electricities ; but 

 exhibits on its surface a modification of electricity, which is 

 perhaps more analogous to the state of a conducting body, 

 the natural electricity of which is decomposed. But this is 

 foreign to our purpose. 



The addition that has just been made to our ideas respect- '^'■'^ requires 



. . . '' . . ^ some altera- 



ing electricity obliges us to a small modification of our no- tioa of terms. 

 menclature likewise. Hitherto we have considered an elec- 

 tricity, which is on the surface that serves to limit two differ- 

 ent bodies, as belonging to the surface of either indiscrimi- 

 nately. Thus the electricity that is between the interior 

 surface of a coating, and the surface of a plate of glass to 

 which the coating is applied, might equally be called the 

 electricity of the coating, or the electricity of the face of the 

 plate. Yet this electricity may have a different relation to 

 these two surfaces : one may be that of a body, through which 

 the electricity in question supports itself by its attraction for 

 another electricity of the opposite kind, and in the thickness 

 ef which it consequently occasions the peculiar modification 

 we have established : while the other of these surfaces may 

 be nothing but the mechanical support as it were of the same 

 electricity, or belong to a body, through which it does not 

 exert the particular action abovementioned.. This is pre- 

 cisely the difference between the surface of a plate of glass 

 and that of its coating, or more generally between the sur- 

 face of the air that surrounds an electrified conducting body 

 and the surface of that body : for we see clearly, that a con- 

 ducting body cannot have two electricities of a different 

 kind on its surface separated by its thickness alone. It is 

 improper therefore, to give the same name to these two dif- 

 ferent conditions. To distinguish them without deviating 



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