ELEC T R I C I T Y. 
424- 
fluid is redundant, there will be an efflux of the con¬ 
tained fluid ; and on the other hand, if tlie body contains 
lefs than its natural quantity of fluid, there will be an 
influx from vvithout. But this efflux or influx may be 
prevented, either by furrounding the body with fubftances, 
through the pores of which the fluid cannot move at all, 
or by the body itfelf being of this conftitution. And 
thus we fee, that the very circumftance of being imper¬ 
vious to the fluid, or completely permeable, renders the 
body capable or incapable of exhibiting eleCtrical pheno¬ 
mena, if furr.6un.ded by permeable bodies. This circum¬ 
ftance is alone fuflicient to conftitute the difference be¬ 
tween eleBrics per fe, and non-cleElrics ; and here a nume¬ 
rous clafs of phenomena receive an explanation by this 
hypothetical conftitution of the eleCtric fluid. All elec- 
tiics per fe are bodies fit for confining eleCtricity in bodies 
which are rendered capable, (by whatever means) of pro¬ 
ducing eleCtrical phenomena ; and no conductor, or fub- 
ftance which allows the electricity to pafs through it, can 
be made eleCtric by any of the means which produce that 
'efleft in infulators. And it is well known, that the elec¬ 
tricity of eleCtrics is vaftly more durable titan that of non- 
eleCtrics in fimilar fituations. When the tendency to ef¬ 
flux or influx is-induced, as hereafter (hewn, by a due 
proportion of the redundancy and deficiency of eleCtric 
fluid, the part of the body where this obtains is by no 
means in its natural ftate, and may contain either more or 
lefs than its natural quantity. But it neither aCts like an 
over-charged nor like an under-charged body, and is 
therefore cabled neutral. Such, for example, is noticed 
in the plates and covers of the eleClxophorus. 
It may be proper to point out fome of the habitudes 
that indicate which end of the conductor is eleCtrical by 
the redundancy of eleCtric fluid. It is generally believed, 
-that the remote end of a conductor which is electrified 
by glafs, excited by rubbing it with flannel-or amalga¬ 
mated leather, is eleCtrical by redundancy. No difference 
has been obferved in the attractions and repulfions; but 
there are other marks of diftinCtion which are conftant, 
-and undoubtedly arife from a difference in the mode of 
aCtion of thofe mechanical forces. If a glafs mirror, 
covered with tin-foil, be made to touch the remote end 
of the conductor, and (lowly drawn tranfverfely, fo that 
the conductor draws a line as it were acrofs it: this mir¬ 
ror being laid down with the foiled fide undermoft, the 
dud, which fettles on it in the courfe of a day or two, 
will be chiefly collected along this line, fomewhat in the 
form of the fibres of a feather. But if the conduCtor 
was rendered eleCtrical by the globe covered with feal- 
ing-wax, the duft will be collected along this line in little 
fpots like a row of beads. The appearances will be re- 
verfed if the rnirrer has been palled acrofs the end of 
the conductor which is neared to the excited eleCtric. 
In diort, in whatever way the drawing point lias been 
electrified, if it repel a ball which has touched excited 
glafs, the line will be feathered ; but if it attraCt fuch a 
ball, the line will be fpotted. There are m;iny ways of 
making this appearance much more remarkable ; but we 
mention this, becaufe the circumdances which occafion 
the difference, whatever it be, are the moft Ample podible. 
Nothing is communicated ; and therefore the effeCt mud 
arife from a fubftance or power redding in the body. If 
it be a fubdance fui generis, the eleCtric aCtion mild arife 
from a different diftribution of this fubdance ; from a re¬ 
dundancy and deficiency of it in the different portions of 
the conductor. Without pretending to fay which is re¬ 
dundant, we {hall fuppofe, with Dr. Franklin, that the 
eleCtricity of excited glafs is fo ; and hence the words 
redundant,, and pofitive, are ufed alike to diltinguidi this 
itate of eleCtricity. 
When an infulated body is brought very near to an 
electrified body, a fpark is obferved to pafs between them, 
accompanied with a noife which is called the [nap ; from 
whence is inferred a transference of eleCtrical matter. 
When a body has imparted eleCtricity to another, it cotv 
dantly repels it, unleis that other has afterwards imparted 
all its eleCtricity to other bodies. This faCt, from which 
'there is-no exception, is an immediate confequence of the 
theory. Before the transference fuppofed by it, one of 
the bodies-was in its natural ftate ; after the transference, 
■both bodies contain redundant fluid, or redundant mat¬ 
ter ; therefore they mu ft mutually repel. 
All the phenomena of communicated eleCtricity rauft 
be more remarkable or forcible, in proportion to -the 
conducting power of the bodies. A very imperfeCt con¬ 
ductor, fuch as glafs or fealing-wax, will impart or re¬ 
ceive fluid only between the very neareft parts ; whereas 
a metalline body is inftantly affected through its whole 
extent. This deduction is perfectly agreeable to the 
whole train of eleCtric experiments. The finger receives 
a ftrong fpark from a large metalline eleCtrified body, 
which difeharges every part of it of a portion of its elec¬ 
tricity. But an excited globe, which (hews, by its ac¬ 
tion on a diftant body, as great a degree of eleCtricity, 
will give only a very fmall fpark ; and it is found not to 
be affected at any confiaerable diftance from the point of 
its furface from whicli the transference was made. The 
whole eleCtricitv of a perfeCt conductor is dilch.arged bv 
touching it; but a non conductor will fucceflively give 
fparks, if touched in many different parts ; and it may 
be feen by a nice electrometer, that each contaCt takes 
away the eleCtricity only from a very fmall fpace round 
it : and it is farther highly deferving of notice, that fome 
time after a fpark has been obtained from a particular 
fpot of the eleCtric, a fecond fpark may he obtained from 
it, the eleCtricity of the neighbouring parts having been 
gradually diffufed over it. 
If an eleCtrified conducting body touch any thing com¬ 
municating with the ground by perfect conductors, all its 
eleCtricity mu ft difappear, and none can appear in the 
■body touched by it; for the mafs of the earth bears fuch 
an unmeafurable proportion to that of the greateft body 
that we can eleCtrify, that when the redundancy or defi¬ 
ciency is divided between them, it mud be imperceptible 
■in boili. Hence the defeent of all lightning into the 
earth ; and.hence the neceftityof inflation, as it is called, 
-or the furrounding by non-conduCtors every body which 
we would have exhibit eleCtric appearances. 
Any uneleCtrified body will be firlt attracted by an 
-eleCtrified body, will touch it, and will then be repelled. 
The neutral body is rendered eleCtrical by induction. It 
is, in confequence of this, attracted, comes near enough to 
receive a fpark, or even touches it, and is then eleCtrified 
by communication ; and, in conf luence of this, it is re¬ 
pelled. This has been confirmed by an endlefs train of 
experiments. It was firft taken notice of by fir Ifaac 
Newton. Otho Guericke mentions many inftances of the 
repulfion, but did not obferve that it was an univerfal 
law. Newton was fo (truck with it as to engage in a con- 
fiderable train of experiments in the early part of his life, 
while meditating on the power of gravity ; but even his 
fagacious mind did not obforve the whole procefs of na¬ 
ture in his experiments. He obferved, that the light bo¬ 
dies which rofe and adhered to tlie rubbed plate of glafs 
were foon after repelled by it ; but did not obferve, that 
the fame piece would again rife to the glafs after it had 
touched the table. This faCt is now the foundation of 
many experiments, which the itinerant electricians vie 
with each other in rendering amufing. There is fre¬ 
quently a feeming capricioufnefs in thofe attractions and 
repulfions. A pith ball, or a down feather, hung, by 
filk, will cling to the conductor, or otherwife eleCtrified 
body., and will not fly off again, at leaft for a long while. 
This happens when thofe bodies are fo dry as to be almoft 
non-conduCtors. They acquire a pofitive and negative 
pole, like an iron nail adhering to a magnet, and are not 
repelled till they become almoft wholly pofitive or nega¬ 
tive. This never happens with conducting light bodies. 
