TOL. L.] PHILOSOPHICAL TRANSACTIONS. 129 



With regard to the experiments that are given to show all vapour to be 

 electrized : in these Mr. Eeles seems to have been led into error, by not having 

 observed that many bodies electrized will retain that electricity for some time, 

 though in contact with conductors. The Leyden phial may be touched 3 or 4 

 times by a quick finger before the whole is discharged. Almost all light, dry, 

 animal, or vegetable substances, such as feathers and cork, do this in a much 

 greater degree : and in general, the more slow any bodies are to acquire electri-< 

 city, the more avaricious they are to keep it. Part of the plume of a feather, 

 hanging to a green line of silk about a foot long, which was suspended from the 

 midst of a horizontal line of the same, about 4 yards in length, was electrized 

 with a dry wine glass according to the method of Mr. Eeles ; and after being 

 touched 9 times with a finger, at the intervals of 2 seconds of time, still mani- 

 fested signs of electricity, by being attracted at the 10th approach of it. 



A cork ball, on the same line and circumstances after being electrized, was 

 touched at the intervals of 10 seconds repeatedly, for 7 times before it was ex- 

 hausted. The fumes of boiling water were conveyed on this ball after being 

 electrized ; and after a fumigation for 30 seconds, it showed signs of electricity, 

 by being attracted to the approaching finger; and after 30 seconds more without 

 any fumigation, it again obeyed the finger ; and again, after 30 more, but at 

 less and less distances. The same appearances occurred from the fumes of resin. 

 Hence he apprehends that Mr. Eeles, having dipped the electrized down of the 

 j uncus bombycinus in vapour for perhaps half a minute (for no time is menti- 

 oned,) and finding it still retained its electric attraction, was not aware that this 

 same would have happened, if he had by intervals touched it with his finger, or 

 any other known conductor of electricity . 



As Mr. Eeles had here objected, that there was no real opposition in the 

 electric aether of glass, and that from wax ; the common experiment to show 

 this was many times repeated with constant success ; viz. the cork ball suspended 

 as above, after being electrized by the wine glass and repelled from it, was 

 strongly attracted by a rubbed stick of sealing-wax ; and vice versa. In the 

 same manner Dr. D. observed the electric aether from a black silk stocking 

 (which was held horizontally extended by the top and foot, and being rubbed in 

 the midst with an iron poker, was applied to the cork ball,) to be similar to 

 that of glass, and opposite to that of wax. But the following experiment ap- 

 pears to put this matter out of all doubt, and to demonstrate that this difference 

 is only a plus and minus of the same specific aether, and not different qualities 

 of it, as Mr. Eeles would suppose. A stick of dry sealing-wax was rubbed on the 

 side of a dry wine glass, and a cork ball, suspended as in the former experiments 

 played for some time between them : but glass rubbed with glass, or wax with i 

 wax did not manifest any electric appearance. Whence it would appear, that in 



VOL. XI. S 



