202 Mr. Morgan's Ohjeivailons and Experiments on 

 flauced fimilai'ly to the acids in the preceding experiment, 

 were attended with iiiiiilar, hut not equal effects, hecaule, in 

 confequence of the inferiority of their condu6ling power, it was 

 necefiary to naake the line through which the charge palled 

 confiderably fliorter. 



4. The brilliancy or fplendor of the ele^lric fluid in its 

 pafiage through any body is always increafed by leilenlng the 

 dimeniions of that body. I would explain my meaning by fay- 

 ing, that a fpark, or the difcharge of a battery which we might 

 fuppofe equal to a fphere one quarter of an inch in diameter, 

 would appear much more brilliant if the fame quantity of fluid 

 is compreffcd into a fphere one-eighth of an inch in diameter.. 

 Thisobfervation is the obvious ccnfequenceof many known facls. 

 If the machine be large enough to afford a fpark whofe length 

 is nine or ten inches, this fpark may be {tzw fometlmes forming 

 itfelf into a brufli, in which flate it occupies more room, but ap- 

 pears very faintly luminous. At other times the fame fpark may 

 be feen dividing itfelf into a variety of rr.mifications which fhoot 

 into the furnmndliig air. In this cafe, likewlfe, the fluid is 

 diffufed over a large luiface, and in proportion to the extent of 

 that furface, fo is the faintnefs of the appearance. A fpark, 

 which in the open air cannot exceed one quarter of an inch in 

 diameter, will appear to fill the whole of an exhaufted receiver 

 four inches Vv'lde and eight inches long. But in the former 

 cafe it is brilliant, and in the latter it grows fainter and fainter 

 as the (ize of the receiver increafes. To prove the obfervation, 

 which I think m.ay be juftined by the preceding fads, I made 

 the following experim.ents. 



EXP. VIII. To an Infulated ball, four inches in diameter, I 



fixed a filver thread, about four yards long. This thread, at 



the end which was remotefl from the ball, was fixed to another 



^ infulated 



