Keply to Mr. De Luc. 201 



iTient taken from Franklin, and will be found in liis " Experi- 

 ments and Observations on Electricity. London 1769," p. 78. 

 The experiment detailed by Mr. De Luc, which, as he observes, 

 " is a peremptory demonstration that the effect of friction is not 

 to open the pores for receiving more electric matter, which is 

 discharged when the friction ceases, as Mr. Donovan conceives 

 it," therefore, does not prove against me, but against Franklin. 



Mr. De Luc declares that '•' an error of Franklin has created 

 all the just objections of Mr. Donovan." They are then ad- 

 mitted to be well founded, and my object is accomplished. It 

 was Franklin, and not Volta, whose opinions I combated ; and 

 therefore Mr. De Luc's observations all relate to the possibiUty 

 of applying to Volta what vvas intended for Franklin ; so tiiat, be- 

 tween the opinions of Mr. De Luc and those which I have ven- 

 tured to being forward, there is as yet no disagreement. 



That I had no ojjportunity of an acquaintance with the Idees 

 sur la Meltorologie and the Traitc elcmerilaire of Mr. De Luc 

 is true ; and I regret that works such as I sui>pose them to be 

 never came within my reach. Living in a city wliere literary 

 advantages of this kind are far less numerous than in other places, 

 I have had often to feel and lament the consequent limitation of 

 my knowledge on subjects with which I was most anxious to be 

 acquainted. 



Of the hypothesis of Volta concerning the standard of electri- 

 cal comparison I was not altogether ignorant ; indeed the only 

 knowledge I possessed on the subject was derived from some 

 papers of Mr. De Luc's in Nicholson's Journal. I formerly. 

 searched into various books with the design of gaining a better 

 acquaintance with Volta's view of this standard, but I was un- 

 able to obtain it. I found, it is true, a paper by Volta in 6,ome 

 of the old Philosophical Transactions, written in Italian : it re- 

 lated to the action of electric atmospheres upon his condenser, 

 but they did not afford _what I desired. 



To enter into a discussion with so experienced a philosopher 

 as Mr. De Luc, were to presume myself what I um conscious of 

 not being. I therefore decline that task, and content myself 

 with barely sul>mitting to him a few suggestions concerning his 

 defence of Volta, and his observations on my objections. 



Mr. De Luc by a striking experiment has illustrated the Voltaic 

 hypothesis. By the continued dispersion of electricity in a room, 

 the air was rendered positive. A pair of insulated pith bulls in 

 the natural state were brought in from an adjoining room : they 

 now diverged negatively ; but wlien returned to the room from 

 whence they came, the natural state was resumed. Mr. De Luc 

 f xplains tliis by supposing that, although the balls were at first 

 >n the natural state when compared with the electric state of that 



room. 



