of the Ley den Jar. ^05 



iiected with Us inner surface were examined. An excited glass 

 tube first attracted, and then repelled them ; when the latter 

 effect was produced, the tube was ascertained to be negative.^ 



Exp. 15. An excited stick of sealing-wax, and the small jar 

 charged negatively, each being separately applied, constantly re- 

 pelled them. 



Exp. 16. The small jar charged positively always attracted 



them. 



ExD. 17. The balls connected with the outer surface were 

 next examined. The excited tube, and the small jar charged 

 positively, constantly repelled them. 



£:i7?.'iS. The excited wax first attracted, and then repelled 

 them ; when the latter effect was produced, the wax was found 

 to be positive. 



Exp. 19. The small jar charged negatively, always attracted 



them. 



On reviewing the foregoing series of experiments, it was evi- 

 dent that the oliject for which they had been undertaken was 

 fully accomplished ; but it seemed requisite to notice and ac- 

 count for the rapid changes which took place in the excited 

 electrical states of the stick of sealing-wax and the glass tube 

 when presented to the surfaces of the jar possessing an electrical 

 titate contrary to their own. For in performing the experiments 

 care was always taken to prevent their coming into contact with 

 the pith-balls, or even approaching nearer to them than was 

 necessary to produce the intended effect. Those changes were 

 clearly occasioned by these two circumstances :— first, the great 

 intensity of the charge upon the surfaces to which the excited 

 bodies were presented ; and secondly, the small electrical capa- 

 city of those bodies in relation to that of the surfaces to which 

 they were opposed. For when the small jar, whose electrical ca- 

 pacitv is so greatly superior to that of either of the excited bodies, 

 was charged, and presented as they had been to the surface 

 possessing an opposite electrical state ; the electrical state of 

 the jar underwent no change of kind, the only effect produced 

 on it being a very small diminution of intensity in the charge. 

 Those changes therefore did not arise from any peculiar property 

 of the jar in modifying or changing the electricity communicated 

 to its opposite surfaces ; for any simply electrified surfiices whose 

 capacity and charge are much superior to those of the excited 

 bodies will produce similar effects, as the following experiments 

 show.— One extremity of a wire which had a brass ball at its 

 opposite end, was inserted in the hole at the extremity of the 

 prime conductor, so as to project htirizontally from it ; and two 

 pith-balls were suspended from the end of the wire that was 

 furthest from the conductor. The machine was put ni action, 

 C c 3 an<i 



