•2&1 PHILOSOPHICAL TRANSACTIONS. [aNNO 1771. 



Strictly conformable to the 11th, 12th, and 13th propositions: but it is needless 

 to point out the agreement, as the explanation given by the authors does it suf- 

 ficiently. 



§ 6. On the Leyden Plal. — ^The shock produced by the Leyden vial, seems 

 owing only to the great quantity of redundant fluid collected on its positive side, 

 and the great deficiency on its negative side ; so that if a conductor was prepared 

 of so great a size, as to be able to receive as much additional fluid by the same 

 degree of electrification, as the positive side of a Leyden vial, and was positively 

 electrified in the same degree as the vial, he does not doubt but what as great a 

 shock would be produced by making a communication between this conductor 

 and the ground, as between the two surfaces of the Leyden vial, supposing both 

 communications to be made by canals of the same length and same kind. 



It appears plainly from the experiments which have been made on this subject, 

 that the electric fluid is not able to pass through the glass; but yet it seems as 

 if it was able to penetrate without much difficulty to a certain small depth, per- 

 haps he might say an imperceptible depth, within the glass ; as Dr. Franklin's 

 analysis of the Leyden vial shows that its electricity is contained chiefly in the 

 glass itself, and that the coating is not greatly over or undercharged. 



It is well known that glass is not the only substance which can be charged in 

 the manner of the Leyden vial ; but that the same effect may be produced by any 

 other body, which will not suffer the electricity to pass through it. 



* Hence the phenomena of the vial seem easily explicable by means of the 

 22d proposition. For let acgm, fig. 20, represent a flat plate of glass, or any 

 other substance which will not suffer the electric fluid to pass through it, seen 

 edgewise; and let sbdv, and Eefp, or Bc/and e/, as he calls them for shortness, 

 be two plates of conducting matter of the same size, placed in contact with the 

 glass opposite to each other; and let nd be positively electrified; and let e/ com- 

 municate with the ground; and let the fluid be supposed either able to enter a 

 little way into the glass, but not to pass through it, or unable to enter it at all; 

 and if it is able to enter a little way into it, let b^id, or bi, as he calls it, repre- 

 sent that part of the glass into which the fluid can enter from the plate hd, and 

 e^ that which the fluid from E/can enter. By the abovementioned proposition, 

 if be, the thickness of the glass, is very small in respect of bd, the diameter of 

 the plates, the quantity of redundant fluid forced into the space sd, or b.^ that 

 is, into the plate sd, if the fluid is unable to penetrate at all into the glass, or 

 into the plate sd, and the space bS together, if the fluid is able to penetrate into 



• The Mowing explication is strictly applicable only to that sort.of Leyden vial, which consists of 

 a flat plate of glass or otlier matter. It is evident however, that the result must be nearly of the 

 same kind, tliough the glass is made into the shape of a bottle as usual, or into any otlier form ; but 

 he proposes to consider those sort of Leyden vials more particularly in a future paper.— Orig. 



