414 PHILOSOPHICAL TRANSACTIONS. [aNNO I759. 



powers, which, by contrasting, and, as it were, counteracting each other, 

 produce the various phenomena of electricity ; and that, when a body is said to 

 be positively electrified, it is not simply that it is possessed of a larger share of 

 electric matter than in a natural state ; nor, when it is said to be negatively elec- 

 trified, of a less ; but that, in the former case it is possessed of a larger portion 

 of one of those active powers, and in the latter, of a larger portion of the 

 other ; while a body, in its natural state, remains unelectrified, from an equal 

 balance of those two powers within it. 



All who allow of positive and negative electricity, know, that the Leyden 

 ^hial, when charged, exhibits electricity in those two states, the one within, the 

 other on the outside; and that when a communication is made between the 

 two, by the means of a non-electric touching the coating, and at the same time 

 approaching the wire, or vice versa, the explosion is produced, and the phial 

 discharged. This reduces the question to a narrow compass ; for if, on the 

 discharge of the phial, we meet with proofs not only of a power acting from 

 within to the outside, but also of a power acting at the same instant from the 

 outside to within, then we may fairly conclude, that what is called negative elec- 

 tricity is, in reality, a positive active power ; and that electricity, in general, 

 consists not of one alone, but of two distinct, positive powers, acting in con- 

 trary directions, and towards e^ch other. 



The proof he offers first, is founded on the following experiment. When 

 the phial is electrified but a little, if we touch the coating of it with a finger of 

 one hand, and at the same time approach a finger of the other hand to the wire 

 we shall receive a pretty smart blow on the tip of each of the fingers, the sen- 

 sation of which reaches no farther : if the phial be electrified a degree higher, 

 we shall feel a stronger blow, reaching to the wrists, but no farther : when 

 again it is electrified to a still higher degree, a severer blow will be received ; 

 but will not be felt beyond the elbows : lastly, when the phial is strongly 

 charged, the stroke may be perceived in the wrists and elbows ; but the princi- 

 pal shock is felt in the breast, as if a blow from each side met there. This 

 plain and simple experiment seems obviously to suggest to observation, the 

 existence of two distinct powers, acting in contrary directions : and I believe it 

 would be held as a sufficient proof by any who should try the experiment, with 

 a view to determine the question simply from their own perceptions. 



But as Mr. S. was sensible that the proof of any important point in philosophy, 

 ought not to depend on the perceptions of this or that particular person, he 

 judged it necessary to have recourse to experiments, the result of which might 

 admit of no ambiguity. The fortunate discovery of M. Muschenbroek and M. 

 Allamand, with the improvements that have since been made on it, puts it in 

 our power to increase electricity to what degree we please. He did not there- 



