ELECTRICAL EXPERIMENTS ON GLASS. 6$ 



to be fixed occasionally to the conductor or the rubbers. 

 In this experiment he fastened one of these rods to the 

 rubbers, and made it communicate with the outer or inner 

 coating, it did not signify which, of a phial placed on an 

 insulating stand ; the other coating of the phial communi- 

 cating with a similar rod fixed to the conductor. The com- 

 munication was made by means of a wire in contact with 

 each coating, and terminating at the other end in a knob, 

 which might be brought near or removed from the other 

 rods at will. This phial, thus completely insulated, was 

 charged by an equally insulated machine. Hence the au- 

 thor infers, that the ground does not contribute to the 

 charge of the phial ; and that, when the apparatus is not 

 insulated, the wood of the table, and that which supports 

 the stand, are the invisible conductors of the fluid from the 

 surface that parts with it towards the point where the fluid 

 is excited on the plate: that in his insulated experiment the 

 use of the rods supplies the place of the ground, and con- 

 ducts the fluid : &c. 



I cannot admit the theory of taking the fluid from the Glass not it*. 

 surface of an impenetrable substance, as Dr. Franklin as- P cnetraoJ e *• 

 serts glass to be; because it is a fundamental law of che- fl u; d. 

 mistry and physics, that no movement can take place with- 

 out a previous impulse, and consequently without immediate 

 action on the substance to be deprived of the fluid. Besides, 

 what substance is there, that the igneous matter cannot 

 penetrate ? and no one will deny, that the igneous matter 

 forms a part of the electric fluid. Accordingly I deduce an 

 opposite inference from this experiment. 



Mr. Lugt then recites several very ingenious experiments, Affinity of 



among others the following on the electrophorus, by which & Iass for th - 

 t u £ ■ ■ i j A ♦• 1 4. i- , electric fluid 



he would go on to prove this singular deduction ; but which shown by 



in reality prove nothing, except that the attraction of the 



igneous fluid, developed at the disk, is strong enough to 



supply the place of the attraction of the ground : in fact, 



that in uninsulated and insulated experiments glass has 



such an elective attraction for the fluid, as to retain the 



same quantity in both situations of the phial. It is still to 



be accounted for, like all chemical and physical phenomena, 



bv the theory of elective attraction. 



He 



