340 Rpjfections on the Inadequacy of the principal Hypotheses 



Concerning the equal distribution of electricity vvhich follow* 

 from the first and second principle, Dr. Franklin observes " that 

 when a quantity of electrical matter is applied to a mass of any 

 bigness or length within our observation (which bath not al- 

 ready got its quantity) it is immediately and equally diffused 

 throughout the whole ■*■'." It is supposed that insensible clec- 

 tricitv exi'^ts naturally in the pores of all bodies, that it can be 

 abstracted and i'orccd to exist in an insulated form, while the 

 body remains vacant. Let us conceive a body either totally or 

 in part deprived of its share of natural electricity, " when a 

 <iuantity of electrical matter is aijplicd, it is immediately and 

 equally diffused through the whole." Now if the body in ques- 

 tion be of glass thus negatively electrified, and if so much scn- 

 ^ible electricity be imparted as was abstracted ; it must be equally 

 ditmsed as before. But it must be remendjered, that the hypo- 

 thesis supposes glass to be impermeable to electricity ; " let it 

 first be considered that we cannot by any means we are ac- 

 <[uaintcd with force the electric fluid through glass f," nor into 

 any part of it, for Dr. Franklin after grinding away 5-6ths of a 

 phial found it no more pervious than before, demonstrating that 

 it was not the middle stratum alone of the glass, as he first sup- 

 posed, which relused a passage to the fluid. I am aware' that 

 he does not allow a similar electricity to exist simultaneously in 

 all parts of the glass : it is enough if he allow that any part may 

 be negatively electrified : for in this case the fluid must have left 

 that part, which it could not do were glass impermeable : and 

 if one part allow a passage, so must every other. Thus the 

 doctrine of equal distributiciu is on all sides surrounded by difii- 

 culties ; it is incompatible with the doctrine of impermeability : 

 if one be adn^itted the other must be rejected. 



The attiaction and repulsion of light bodies comes under ex- 

 amination in this place. Dr. Franklin conceives that all matter 

 is full of the electric fluid, and that a mutual attraction subsists 

 between both. Now if matter can contain no more it is be- 

 eause it has no further attraction : for from the nature of an 

 equilibrium all attractions must be saturated. This conclusion 

 is confirm.ed by his statement that " if more be added, it lies 

 \vithout upon the surface, arid forms what we call an electric at- 

 inosphere," which could not happen unless the attraction of the 

 body to more were destroyed. From all this it follows that at- 

 traction is exerted between matter and its natural quantity only 

 of electricity, but in the ordinary state of things this attraction 

 is insensible. Facts, however, convince us that a sensible at- 

 tractioa exists between free electricity and matter which already 



* Ffanklin's Letters,. 55n % Ibid. 73. 



•ontains 



