406 Refleclims on the Inadequacy of Ihe piincipal Hijpollieses 



the powers pass entire through the glass." But this experi- 

 ment does not prove its object, inasmufh as it is equally ex- 

 plained by the hypothesis of Franklin : and of the latter mode 

 of explanation Mr. Eeles does not seem to have been aware. 

 If positive electricity be thrown on one surface of the glass, 

 Franklin supposes that it repels a similar (juantity from the 

 opposite side ; this portion issuing from the glass will enter sur- 

 rounding bodies, and cause them to !.^e repelled. But it is diffi- 

 cult to understand what advantage can arise to the h\^othesis 

 in question, by the supposition of permeability: on the contrary, 

 it seems to offer an insuperable objection to the opinions con- 

 ceived in the following principle. 



4. The chief phaenomenon to be accounted for by this part of 

 the hypothesis is the charging of the Leydcn phial. This Mr, 

 Eeles states to be effected in the following manner : The electri- 

 city thrown into the jar "mIII repel the power of the same kind 

 from the opposite side of the glass, and attract the different 

 power from the non-electrics; {i.e. the connection with the 

 ground.)" The explanation is more circumstantial in the fol- 

 lowing passage : '^' When a spark of the vitreous power is taken 

 into the bottle, an equal quantity of the resinous power goes 

 from the inside of the bottle to the conductor ; by which means 

 the bottle is electrified with the vitreous power: but when you 

 apply a non-electric to the outside of the bottle, part of the 

 vitreous power goes to the non- electric (/. e. the communication 

 with the ground) in exchange for an equal quantity of the re- 

 sinous power drawn to the outside of the bottle, which resinous' 

 power is held there bv the attraction of the vitreous power oa 

 the inside of the bottle." 



If then the contrary powers are situate on each surface of the 

 charged phial, and if they strongly attract each other through its 

 substance, why do they not pass through it and combine, since Mr. 

 Eeles supposes that glass is permeal)le to each kind of electricity ? 

 But passing this objection, it will be found that his manner of 

 explaining the charging of the phial is encumbered with much 

 improbability and difficulty. Mr. Eeles states that " the electric 

 powers are never rendered visible except in their passing from 

 one body to another, in opposition to each other, when they 

 condense each other into the form of flame." In charging it 

 is therefore manifest, that as long as sparks are seen between the 

 conductor and the ball of the phial, it is an infallible indication 

 that the two powers are passing in ojiposition to each other ; the 

 negative j)ower is passing from the inside towards the conductor, 

 and the positive from the conductor into the phial. These two 

 powers necessarily meet and " condense each other into the form 

 of flame :" they return to the natural state, "and therefore do 



Viot 



