36 Professor Leslie on Electrical Theories. 
may balance the accession F j'c in the time i. Plence the force 
which tends to separate the particles of BD must be n times 
greater than that which disturbs the texture of AB or DE, If 
B D be shortened, G e will be proportionally increased ; there- 
fore B 13 wiM burst with greater force. The same reasonings 
will apply with little variation in the case of an ordinary dis- 
charge ; for if the end A is connected, (PL I. Fig. 14.), to the one 
coating, and I is brought near a wire communicating with the 
other, G e will be n times greater than F whence the dis- 
uniting force is always greater in BD than in AB or at E, and 
increases as BD is contracted. It is obvious that the same in- 
ferences may be drawn, if we suppose BD to consist of the same 
substance with the rest of the conductor, but only narrower. 
If the conductor, even though it be continuous, is surrounded 
about the middle with a slow conducting substance, the adjacent 
particles will be strongly electrified, while the remote ones will be 
little affected, and hence, if the force be sufficient, the substance 
will burst outwards: And, if the substance is an extremely 
slow conductor, though continued all along the proper conduc- 
tor, it may be forcibly detached ; for, at a distance from the 
source, it will derive its electricity from the contiguous matter. 
The foregoing principles will explain an immense variety of 
phenomena. I shall notice only a few. 
Hence, the discharge is luminous through water inclosed in 5 
short tubes, but never along extended wires ; for in a thin cylin- 
der of water, the electricity is too much attenuated, and, in me- 
tallic conductors, the interval is too short, to allow a sensible 
emission of light. A chain is indeed marked out with a lucid 
track, but this proceeds from the air in contact with the points 
of the links, which retain their electricity after the transmission 
is made by the metal ; which might be evinced by performing 
the experiment in vacuo *. 
Plence, if water, oil, &c. be inclosed in a small glass-tube, 
and two inserted wires be brought near the middle, the tube 
* A very beautif ul appearance is produced , by sending a small shock through a 
long iron chain , suspended f rom glass pillars in festoons. Bright yellow corruscations 
are seen to dart from the end of every link. This effect is occasioned by the oxida- 
tion of the points of the iron , and therefore ceases along any part of the chain which 
has been laid m water i 
