ANALYSIS OF THE GALVANIC PILE. <2<J7 



power, depending on the quantity of vector. This distinc- 

 tion is partici'hry manifested by the changes, that happen 

 along an insulated conductor of some length, when an elec- 

 trified body is placed at some di-tance from one of i is ex- 

 tremities. It is known in genera!, that tie extremity of *ut>h 

 a conductor next to the electrified body acquires an electric 

 state contrary to tiiat of the body, vvhi-le its-opposite extre- 

 mity has the same electric state as that body : for instance, 

 suppose the electrified body to be positive ; it is commonly 

 said, that the extremity of the conductor next to this body 

 becomes negative, and the opposite extremity positive ; but 

 these are vague expressions, and as they give no veal idea 

 of the effects, they have occasioned the va:iery of systems, 

 all unsatisfactory and therefore changing, hitherto made on 

 these phenomena. 



The cause of obscurity on this object is the want of that Distinction b^- 

 distinction above mentioned, between the expansive power, p ans i ve power 

 and the density of the electric fluids, belonging to its nature, an< * density 

 as expansible. Every fluid of this class, when confined 

 within a certain space, has necessarily the same degree of 

 expansive power in every part of this space, since this is at- 

 tached to the very idea of expansibility, but it is not the 

 same with respect to density. For instance : a mass of air, Illustrated by 

 confined in a certain space, has certainly, in all its parts, ^ t aCtK>n 

 the same degree of expansive power, whatever ehange may 

 happen in its partial density. If then a hot body be placed 

 near one side of this mass of air, its density will diminish in 

 this part, and increase in the more remote: or if a piece of 

 ice be brought on one side of this mass of air, its density 

 will increase near the ice, and diminish in the remote parts ; 

 but the degree of expansive power of this confined air will 

 always be equal in all its parts at the same time, increasing 

 or diminishing in the whole. 



The case is exactly the same with respect to the electric Instanced in 

 fluid on an insulated conductor: an insulated positive body electricity, 

 being placed near one part of the latter, this part receives 

 some of the vector which forms around the positive body a 

 kind of atmosphere, as the hot body has around it an at- 

 mosphere of igneous fluid; and the 'former produces an in- 

 crease of the expansive power of the electric fluid on this 

 part of th^ conductor, as the hot body produces it in the air 



next 



