402 On the Franklinian Theory 



the electrical states of the surfaces of ajar under the condition.* 

 mentioned by him as necessary to obtain the specified results; 

 and at the same time, if I found that they occurred, to ascertain 

 the cause or circumstances which produced them. Accordingly, 

 besides a jar with its pith-balls and insulating stand, the fol- 

 lowing additional apparatus was selected for the purpose. A 

 smooth glass tube, two sticks of sealing-wax, a pair of pith- 

 balls suspended from an insulating stand, a gold-leaf electrome- 

 ter, and a small Leyden jar. 



Before I proceed to describe the experiments, it is proper to 

 give notice, first, that as the investigation occupied the space of 

 at least five hours (all the experiments having been several times 

 repeated), whenever it appeared that the charge of the jar was 

 sensibly diminished, the machine was put in action till the charge 

 was restored to its original intensity ; — secondly, that the pith- 

 ball and gold-leaf electrometers were placed in such situations 

 as to be out of the influence of the charged jar ; — thirdly, that 

 the balls of the former were kept diverging with negative, and 

 the leaves of the latter with positiit electricity ; — and lastly, that 

 one of the sticks of sealing-wax was reserved for examining the 

 balls connected with the inside of the jar (except where it is 

 otherwise mentioned), while the other was exclusively used for 

 electrifying the ])ith-ball electrometer, and examining the balls 

 connected with the outside of the jar. 



Exp. 1 . The inner surface of the jar being connected with 

 the prime conductor, and the outer with the ground, a very 

 strong charge was communicated to it, and the connexion with 

 the ground removed. A stick of sealing-wax about an inch in 

 diameter being strongly excited, was brought suddenly towards 

 the balls connected with the inner surface, and they were in- 

 stantly attracted by it ; but the wax being kept for a moment 

 at the same distance, the attraction ceased, and the balls re- 

 turned to their original position. 



Exp. 2. The wax being excited again as before, was brought 

 slowly towards the pith-balls : the attraction between the wax 

 and them was perceptible, though it was weak and momentary; 

 but when the wax was brought nearer, jepulsion took place be- 

 tween it and the balls, which then kept briskly receding from 

 the wax. The wax being now withdrawn, was presented to 

 each of the electrometers in succession; and by these tests the 

 wax was found to be in a positive state of electricity. 



Exp. 3. The positive electricity on the wax being taken off, 

 it was again excited negatively, and presented to the balls as in 

 Experiment 2, with the same results ensuing. After the balls 

 had been repelled several times by the wax, it was withdrawn 

 and brought suddenly towards the balls connected with the 



outside^ 



