New Outlines of Chemical Philosophy. 429 



some experiments and observations on electricity, in which he 

 attempted to prove that glass is permeable to the electric fluid- 

 The frentlemau who wrote a critique on that work in the Monthly 

 Review, being a Franklinian, objected to the experiments which 

 related to the permeability of glass, in a manner which did not 

 exactly accord with the author's ideas of the subject. In the 

 year following, IVIr. Lyon published some " further proofs that 

 glass is permeable by the electric effluvia." The same gentle- 

 man who reviewed the former work reviewed this also ; and some 

 drops of ink were spilt between the two disputants, which might 

 have been spared without doing much harm to the subject. 



I do not remember to have seen, since that time, any attempt 

 to subvert the Franklinian theory (as it is called), till I read the 

 papers of Mr. Donovan and M. De Luc in the present volume. 

 Mr. Donovan observes " that glass is, in the strict sense of the 

 word, permeable to electricity, yet the fluid passes through it 

 with so much difficulty and so slowly that Franklin's position 

 might be admitted." 



In the first obsei'vation Mr. Donovan is certainly correct j but 

 as to the time of its passing, this learned philosopher seems to 

 have been deceived, by his having made use of coated glass. 



My experiments on this subject prove, not only that glass is 

 permeable by the electrical elements^ but that they pass through 

 it instantaneously, 



Exp. 5. I took a pint decanter with a glass stopper ground to 

 fit into it very exactly, and to one end of a piece of thermometer- 

 tube two slips of Dutch gold-leaf were fixed with gum-water; 

 the other end being fixed with sealing- wax to that part of tlie 

 stopper which goes into the decanter. This tube being suspended 

 in the axis of the glass, its mouth was closed by the stopper as 

 perfectly as could be done with glass^ without the use of the 

 blow-pipe. 



The decanter being suspended by its neck, and an excited ba- 

 rometer-tube caused to vibrate under it, at the distance of two 

 or three inches, the gold-leaves vibrated nearly as much as they 

 would have done had the glass been open at the bottom. 



From a great number of experiments made with this appa- 

 ratus, I concluded that the electrical elements pass through glass 

 instantaneously. But it may be said that the electrical element 

 went into the glass between its neck and the stopper. This is 

 not impossible, though not probable ; for the element must have 

 first passed over the outside of the glass from the bottom to the 

 tO]), and then from the top to the bottom on the inside, a distance 

 jio less than seventeen inches. However, it must he admitted 

 that no devionstralion contains a single step that is in the least 

 douitful. To demonstrate in tlie most satisfactory manner, 



that 



