C% ElECTftlCAL EXPERIMENTS ON GlA£S. 



IX. 



Electrical Experiments on Glass considered as a Ley den PhiaU 

 and on coaled Panes; by Mr. ***** 



Experiments VyHANCE having thrown in my way two papers written 

 SVedoctirfneof * n ^ utcn ^y Mr. Lugt, I was surprised on reading them to 

 plusand minus find, that this gentleman could admit the theory of plus 

 e ctncity. an( j mmus electricity, while almost all his experiments con- 

 cur in proving, that there is an actual passage through the 

 pores of the glass, when it has a communication on one side 

 with the prime conductor of an electrical machine in action, 

 and on the other with conducting bodies communicating 

 with the ground : and that to obtain this passage it is not 

 necessary for the glass to be coated on both sides, as it is 

 sufficient for that in contact with the machine to be so, and 

 to touch at a single point some substance that is but an im- 

 perfect conductor, as the wood of a table, or the like, which 

 has sufficient force to communicate the attraction of the 

 Earth through its pores. Thus I have always suspected 

 the charge of the cascade is effected, in the 5th experiment 

 of my first letter to Mr. van Mons : but as the phial seems 

 to retain in its pores a portion of the electric fluid, and col- 

 lect on the surface communicating with the ground a large 

 quantity of fluid sensible both to the touch and sight, 

 when we charge highly a phial not coated on that side ; I 

 Glass ha* a have thought the force of attraction of glass for this fluid 

 powerful affi- wag so p OVver f u ] j t h a t Abbe Nollet had reason to suspect it 

 electric fluid, attracted electricity from the Earth, which however did not 

 happen in the experiments of Mr. Lugt, as for instance the 

 following, which is the second of his first essay. 

 Insulated phial He procured an apparatus completely insulated by means 



charged by an f f our gi u3S feet. Thus he could at pleasure leave the 

 insulated ma- . . . . _ ... . 



chine. whole insulated ; or form a communication between the 



ground and the conductor, or the ground and the rubbers, 



which were united together by a semicircle of metal placed 



«bout a foot from the insulated plate. Rods were contrived 



* Journal de Physique, vol. LX1V, p. 371. 



to 



