on Mr. De Luc's Paper. ^31 



as a pair oi pitk-hnlls. When these disks were laid together oji 

 7uater they diverged, and the cause of that divergence was vi- 

 sille: both disks jL^ave soap to the tvafer between them, but only 

 07ie to the external water on both sides ; and the disks moving 

 towards this, thcv separated from each other, or diverged. 



Returning to electric motions^ Volta's theory was submitted 

 to direct verification by the experiment whicli Mr. Donovan ex- 

 amines. But I shall first remark, that by changing the expres- 

 sion whioh I had used in explaining these plioeuomena, he has 

 not undcrtood me, nor could he understand Volta's theory. H^ 

 uses the expression vaiiiral stale, to define the electric state of 

 the air in the room next to that in which an electric machine 

 was set in mction ; whereas 1 Jiad u«^ed the expression, the ac- 

 tual electric state of the air in that ruom, in which the pair oj 

 lulls which were in the savie electric state did not, nor could 

 not diverge. If therefore Mr. Donovan in his reasoning change.^ 

 the expression natural state, into that of actual and local elec- 

 tric state of the ambient air, he will find that his objection is 

 not apphcablc to the exnlanation of the phenomena which I 

 have observed. 



jMr. Donovan makes this objection, " that the p^jV of InJh. 

 brought from the next room, when coming in a positive atmo- 

 sphere should be rendered positive, and continue to diverge so, 

 when brough.t back to the first room." Tiiis was not the case, 

 however. Therefore Mr. Donovan's objection is against a fad. 

 But this would certainly have happened, lud that pair of balU 

 remained long enough in the room of the electric machine; for 

 the air communicating at least its own electric state, tliey would 

 then cease to diverge; but in that case, wIipu brought back t<> 

 the first room, instead of coliapsing, thev would have diverged as 

 positive; having thus changed thciv electric stale. Now Volta's 

 theory explains all thc-o case": : it is founded on tliis property 

 of air, that it is a non-cam luctur, and cannot communicate thii 

 electric fitiid to the bodies which it surrounds, or take some from 

 them but in ahsalute contact) and from this circumstance pro- 

 ceeds the insulation of electrified Ijodies in air. However, by 

 the continuance of the co?ilact of the particles of air, these bodies 

 are by degrees reduced gradually to its electric state. 



With respect to electric influences, no true conclusion can be 

 derived from experiments on that object when the air is not 

 ^ dry. For moisture is produced in the air by aqueous vaporn; 

 a conductivg flnid; wherefore, in all mv electric experiments, I 

 had in the same room the hygromeler of my construction, and 

 I made them at times when that hygrometer stood at about th<" 

 eame degree, as I have stated it in niy paper in Nicholon's Phi- 

 losophical Journal. Mr. Donovan had not tlus test in his cxperi- 

 ' incuts 



