[ 20g ] 
of them, and returned the fame way, leaving them 
all in the fame ftate in which it found them j and 
a great number of lateral explofions might be taken 
at the fame time, in different parts of the circuit, 
fome of them very near one another. 
It made no difference, whether the lateral explofion 
was received on a flat fmooth furface, or the points of 
fine needles. In both cafes, the fpark was equally 
long and vivid. 
1 had no fooner completed thefe experiments on 
the lateral explofion ■, but I had a curiofity to fee 
what kind of an appearance it would make in vacuo-, 
fince no other phenomenon in electricity refembles it. 
In all other cafes, the eleCtric matter rufhes in one 
Angle direction ; whereas, in this, it goes and returns 
in the fame path, and, as far as can be diftinguifh- 
ed, at the fame inftant of time ; fo that all the 
difference of the two electricities, which are fo con- 
fpicuous in vacuo, mult here be confounded. Ac- 
cordingly, I found, though my pump was not in 
good order, that I could perceive this explofion in 
vacuo , at the ends of rods, placed feveral inches 
afunder ; and when they were brought within about 
two inches, they feemed to be joined by a thin 
blue or purple light, quite uniform in its appearance. 
As thefe rods were made to approach, this light grew 
denfer; but ftill exhibited no fuch variety, as is ob- 
ferved between the bodies that give and receive elec- 
tricity, in the common experiments in vacuo. 
I was pretty foon convinced, that uncoated jars 
could not be ufed to any more advantage in thefe ex- 
periments, than thofe that were coated ; fince the 
want of coating only operated as an interruption in 
Vol. LX. E e the 
