4W 
ELEC T K 
-and foie ; and if once changed by communication with 
■uneleCtrified bodies, it can never- be recovered again 
without fome new excilement. 
2. If the Idle be touched by any body communicating 
with the ground, fluid will come in, till the repuliion of 
the redundant fluid in the lole for a fuperficial particle y 
is equal to the attraction of the redundant matter in the 
cake for the fame particle. The under furface will be 
neutral, and the fluid will increafe in denfity toward the 
furface DC. The foie contains more than its natural 
quantity of -fluid, but is neutral by the balance of oppo- _ 
fire forces. Let it now be infulated. This difpolition of 
'fluid may be called the common Jiate of the elfdtrophorus. 
3. Let the cover GH B A be laid on it. .The particle 
z, at the upper furface of the cover, mud be more at¬ 
tracted by the redundant matter in the ftratum AB^a, 
than it is repelled by the redundant fluid in the remoter 
ftrata ; for the fluid in the cake is lefs than what belongs 
to it in its natural (tate, and therefore z is attracted by the 
cake. The redundant fluid which has come into the re¬ 
mote fide of the foie is lefs than what would faturate the 
redundant matter of the cake, becaufe it only balances 
the excefs of the remote action of this matter above the 
nearer aCtion of the comprelfed fluid in the foie; and 
this fmaller quantity of redundant fluid aCts on z at a 
-greater diftance than that of the redundant matter in the 
cake. On the whole, therefore, the particle z, lying im¬ 
mediately within the furface G H, is attracted ; therefore 
fome will move toward the cake, and its natural (late of 
uniform dilfufion through the cover will be changed into 
a violent date, in which, it will be comprelfed on the fur- 
face A B, being abdraCted from the furface GH. It 
will now have a dratum GijpH, containing redundant 
matter, and another gp B A, containing redundant fluid. 
But this will didrub the arrangement which had taken 
place in the foie, and had rendered it neutral on the under 
furface. We do not attend to the fluid in the cake, but 
conlider it as immoveable, for any motion which it can 
get will be fo fmall, that the variations of its a.ftion will 
be altogether infignificant. The particle y, fuuated in 
that furface, will be more repelled by the comprelfed 
fluid in the ftratum gp C A than it is attracted by the 
equivalent but more remote redundant matter in GH pg. 
Fluid is therefore difpofed to quit the furface E F, and 
the foie appears politively eleCtric ; very little indeed, if 
the cover be thin. All this may be obferved by attaching a 
fmall Canton’s electrometer to the lower furface of the foie. 
4. A particle of fluid z, placed immediately without 
the furface G H, will be more attracted by the deficient 
-ftratum GH/yg and by A B ba, than it is repelled by the 
redundant ftrata beyond them, and the cover mu ft be fen- 
fibly negative, This is ■■the common (late of the whole 
inftrument after fetting on the cover. It is (lightly pofi- 
tive on the lower furface of the foie, and much more 
fenfibly negative on the upper furface of the cover. A 
fmart fpark will therefore be feen between it and the fin¬ 
der, fluid will enter, till the attraction of the redundant 
matter in A B ba is balanced by the repuliion of the re¬ 
dundant fluid in DCFE. 
5. A fpark will now be obtained from the foie, becaufe 
it was faintly pofitive before, and there has been added 
the aCtion of the fluid which has entered into the cover. 
The fluid in the foie is .therefore difpofed to fly to any 
body prefented to it. But when this has happened, the 
equilibrium at the furface G H is deftroyed, and that 
furface again becomes negative, and w ill attract fluid, al¬ 
though the cover already contains more than its natural 
quantity. A fmall -fpark will therefore be feen between 
the cover and any conducting body prefented to it. By 
touching it, the neutrality or equilibrium is. reftored at 
(> H; but it is deftroyed again at E F, which will again 
give a pofitive.(park, which, in its turn, again leaves G H 
negative. This will go on for ever, in a feries of com¬ 
munications continually diminilhing, fo as loon to become 
- I C I T Y, 
iiifenfible, if the three parts of the electropnorus be 
thin. This makes it proper to make them otherwife, it 
the inftrument be intended for illuflrating the theory. 
At laft the equilibrium is completed at the Surfaces 
GH and E F, and both are.neutral in relation to fur- 
rounding bodies, although both the cover and foie con¬ 
tain more than their natural (hare of eleCtric fluid. We 
may call this the neutral or dead (late of the eleCtropbo- 
rus. This ftate may be produced at once, inftead of do¬ 
ing it by thc-le alternate touches of GH and -E F. If we 
touch at once both thefe furfaces, we have a bright pun¬ 
gent fpark, and a fmall (hock. If this be the object of 
the experiment, the ftate N°. 4, which gives occafion to 
it, may be called the charged ftate of the electrophprus. 
When the inftrument has thus been rendered neutral 
in relation to furrounding bodies, it is plain that it may 
continue in this ftate for any length of time without an/ 
diminution of its capability of producing the other phe¬ 
nomena, provided only that no fluid pafs from the cover 
to the cake. We do not fully underftand what prevents 
this communication, nor indeed what prevents the rapid 
efcape from an overcharged body into tire air. This 
caufe, whatever it be, operates-here ; and the beft way 
of preventing the diflipation, or the abforption by the 
cake, is to keep-the eleCtrophorus with its cover on. It 
will come into this’ neutral ftate by diflipation from the 
foie, and abforption by the cover, in no very long time; 
and after this, will remain neutral, retaining its power 
with great obftinacy, efpecially if the cake and plates are 
very thin. 
6. If the cover be now removed to a diftance, both 
parts of the apparatus will tbew ftrong marks of electri¬ 
city. The cover contains much redundant fluid, and 
muft appear ftrongly pofitive, and will give a bright 
fpark, which may be employed for any purpofe. It may 
be employed for charging a jar pofitively by the knob, if 
we juft touch the cover with the knob. The foie will 
attract fluid, or be negative, although it contain more 
than its natural quantity of fluid, and it will take a fpark. 
The foie, therefore, in the abfence of the cover, may be 
employed to charge a jar negatively by the knob. By 
touching it with the finger, or with the knob of a jar 
held in the hand, it is reduced to the common ftate de- 
fcribed in N°. 2 ; and now all the former experiments 
may be repeated again in the fame order. We may call 
this the aflivc or the charging ftate. 
Volta, its undoubted inventor, called it clePlroforo per- 
petuo ; for it appears, as has been already obferved, to con¬ 
tain a magazine of eleftricity. The cover, when re¬ 
moved, will charge a jar held in the hand pofitively ; 
and having done this fervice, it will charge a jar nega¬ 
tively when again fee on the cake. The foie, in the ab¬ 
fence of the cover, will charge a third jar negatively ; 
and then w r hen the cover, after being touched, is fet 
down again, if will charge a fourth jar pofitively 1 . It 
may not be difficult to contrive a fimple mechanifm, con¬ 
nected with the motion of the cover, which (hall connect 
the joined parts with two jare, and (hall connect them, 
when feparated, with two others; and thus charge all the 
four with great expedition. This can be done without 
any new excitation of the eleCtrophorus. But it is by 
no means a magazine of electricity, which it gradually ex¬ 
pends: it is a collector of electricity from the furrounding 
bodies, which it afterwards imparts to others, and may 
be employed to difeharge jars in the fame gradual man¬ 
ner as to charge them. 
7. If the electrophorus be not infulated, a fhoclc may 
(till be obtained, by firft touching the foie, and then, 
without removing the finger, touching the cover: but 
this will not be fo fmart as when the negative cover i-s 
touched at the fame time that we touch the foie, more 
highly pofitive, than when it communicates with the 
ground. The ditference, muft, however, be almoft im. 
perceptible when the pieces are thin, 
1 
8. If 
