BENJAMIN FRANKLIN 33 



exclusively to either of these classes ; the truth being merely, 

 that different bodies admit the passage of the electric influence 

 with extremely different degrees of facihty, and that those 

 which transmit it readily are called conductors, — the metals, 

 and fluids, and living animals particularly belonging to this 

 class ; while such as resist its passage, or permit it only with 

 extreme reluctance, — among which are amber, sulphur, wax, 

 glass, and silk, — are described by the opposite denomination. 



The beginning of the year 1 746 is memorable in the annals 

 of electricity for the accidental discovery of the possibility of 

 accumulating large quantities of the electric fluid by means 

 of what was called the Ley den jar, or phial. M. Cuneus, of 

 that city, happened one day, while repeating some experiments 

 which had been originally suggested by M. von Kleist, Dean 

 of the Cathedral in Camin, to hold in one hand a glass vessel, 

 nearly full of water, into which he had been sending a charge 

 from an electrical machine, by means of a wire dipped into it, 

 and communicating with the prime conductor, or insulated non- 

 electric,- exposed in the manner we have already mentioned to 

 the action of the excited cylinder. He was greatly surprised, 

 upon applying his other hand to disengage the wire from the 

 conductor, when he thought that the water had acquired as 

 much electricity as the machine could give it, by receiving a 

 sudden shock in his arms and breast, much more severe than 

 anything of the kind he had previously encountered in the 

 course of his experiments. The same thing, it was found, took 

 place when the glass was covered, both within and without, 

 with any other conductors than the water and the human hand, 

 which had been used in this instance ; as, for example, when it 

 was coated on both sides with tinfoil, in such a manner, how- 

 ever, that the two coatings were completely separated from each 



