Electrical experiments; illustrating the theory, practice and application of the science of free or frictional electricity

LIBRARY OF
WELLESLEY COLLEGE

PRESENTED BY

Edith Milwood Perrin '10

N

ELECTRICAL

EXPEEIMENTS;

ILLUSTRATING

THE THEORY, PRACTICE, AND APPLICATION OF THE SCIENCE

PEEE OE EEICTIONAL ELECTEICITY :

CONTAINING THE

METHODS OF MAKING AND MANAGING ELECTRICAL APPARATUS
OF EVERY DESCRIPTION,

jfumBrntis SllttHtrEtinB cgHgraiimgs,

G. FRANCIS, F.LS.

AUTHOR OF THE DICTIONARY OF ARTS AND SCIENCES ; CHEMICAL EXPERIMENTS ; THE DICTIONARY

OF PRACTICAL RECEIPTS ; THE DICTIONARY OF TRA.DE COMMERCE, AND NAVIGATION

THE ART OF MODELLING WAXEN FRUIT AND FLOWERS ; MANUAL OF

LEVELLING ; LITTLE ENGLISH FLORA ; FAVORITES OF THE

FLOWER GARDEN ; GRAMMAR OF BOTANY

ETC. ETC. ETC.

FIFTH EDITION.

D. FRANCIS, 21,. MILE END ROAD, & G. BERGER, HOLYWELL STREET,

STRAND.

1850.

D. PEANCIS, PRINTER, MILE END ROAD.

PREFACE.

A WORK entitled ** Electrical Experiments" must necessarily be in some degret
copied from former treatises ; the more especially as the best experiments
and it may be said the best-constructed apparatus, with but few exceptions,
are the result of the ingenuity or the reflection of those who studied the
subject half a century ago, when electricity was all in all with lecturers as
well a» with philosophers ; and when the discoveries in it rapidly succeeded
one another, each more curious, beautiful, or important than its predecessors.

At this earher period, namely, from about 1 740 to the beginning of the
present century, philosophers were learning the facts of the science by long
series of experiments ; lecturers were teaching these facts and giving them
popularity by the invention of ingenious apparatus, and showy illustrations,
and authors were careful to embody these interesting particulars in their
various' ^treatises ; hence the works of Priestley, Adams, Cavallo, Ferguson,
Hawkesbee, Singer, and others, abound with experimental interest. This time
has now past ; the experiments proved the facts, the facts suggested the laws
of the science, and these becoming known, the learned with few exceptions
turned their attention to other matters. If they have condescended to write
upon the subject of frictional electricity, they have in all the latter treatises
given merely a dry explanation of facts and laws, apparently regarding the
detail of experiments as beneath their notice, and forgetting that tyros in
science must have their senses gratified as well as their minds enlightened »
and equally oblivious of the truth, that a fact illustrated by a pleasing popular

PREFACE.

experiment often fixes itself upon the memory, which without that experi-
m-ent, would fail to he remembered, or even regarded.

The Author of this little work impressed, as he has ever been, with the
opinion that the more interesting and amusing a science may be made, the
more it will be studied, has endeavoured to collect all the good experiments
he has met with elsewhere, and has invented many, as further illustrations
of certain parts of the subject. He has been accustomed to make all his
own apparatus, and to lecture on natural philosophy for many years. The
remarks appended therefore to numerous experiments may be considered
practical, and the descriptions also of all the apparatus are original, and it is
hoped as plain as they could be made. In speaking hov/ever of the originality
of the descriptions, it is to be remarked, that some portions of the present
work were written by the Author for the " Magazine of Science," of which
he was the Editor.

This treatise contains more experiments and illustrations than any other
work upon the subject, and all the facts that are known with certainty relative
to frictional electricity, although some disputed matters, such as the origin of
electricity, and whether there be one fluid or two, are very briefly discussed,
they being matters of mere conjecture, and in whichever way they may oe
decided, will make no difference whatever in the practical and populai
development of the science, at least according to our present applications
of it.

G. FRANCIS, F.L.S.

Electricity teaches the laws and effects of a peculiar substance or influence
called the electric fluid, and derives its name from the Greek word electron,
amber ; the first electrical effects having been observed in that substance.

Daily observations on recurrent phenomena, as well as direct experi-
ments, prove that the whole earth and atmosphere, below, upon, and above
the surface, is pervaded by this highly-elastic and subtle fluid, sometimes in a
disturbed state, producing then the most stupendous phenomena ; at other
times in a latent condition, and although then imperceptible, yet not on that
account less abundant. If it be not the very essence of life and existence,
it acts a very important part in the animal and vegetable economy. Over
chemical and meteorological change its power is no less extraordinary. It is
easily proved identical with the vivid and withering lightning, the streaming
aurora, the rapid whirlwind, the terrific waterspout, the rolling pillars of
sand of the desert, and in all probability produces the falling meteor, and the
devastating earthquake.

These are some of the more obvious efi'ects of the electric fluid
when in that free condition in which it is produced by mechanical means ;
without considering the modifications of it which accompany chemical action,
called galvanic ; or it might be described not merely as regulating solitary
phenomena, but as occasioning all the multitudinous effects of chemical
composition and decomposition ; of crystallization ; perhaps of hght, heat
and combustion ; and as analogous to magnetism and gravitation. Although
the earth and atmosphere are alone subject to our experimental researches,
yet there is just reason to conclude that it abounds throughout the universe
as the elemental fire which fills all space, and that it is the mighty power
that is employed by the Great Creator, to move, restrain, and regulate the
millions of worlds with which it has pleased him to fill the vast and brilliant
firmament.

Besides the value of electricity in teaching us the laws and effects of
the fluid we have been describing, in thus explaining so many of the grandei
phenomena of nature, and directing us to guard our persons and property in
some degree against their destructive effects — the science has other claims
to our notice. Its application has been found efficacious in curing some of
the most hngering and painful diseases ; the general laws to be remembered
are few ; all the apparatus necessary may be made either by ourselves or by
ordinary workmen at little expense ; the experiments require for their suc-
cess only common care and attention, and yet are so brilliant, so varied, and
so surprising, as to be a never-failing source of wonder and delight.

It is surprising that a fluid thus universally distributed, and which is capable
of such extensive application, should have remained almost unknown until very
modern times. Although Theophrastus, who lived more than 2400 years ago,
writes that amber, and another body which he called Lyncurium, when rubbed,
were capable of attracting towards them light substances, yet this solitary ex-
periment, not explained till so many centuries afterwards, was the whole
knowledge the ancients had of electricity; and it was not till the latter part of the
sixteenth century, when Dr. Gilbert, by discovering that other bodies had similar
properties, drew in some degree the attention of philosophers to the subject.
Still there was so little to engage pubhc attention, that seventy years elapsed
before the electric light was seen. This was discovered by Mr. Boyle, and
was enough to stamp with the dignity of a science, what had before been
considered as but trivial and unimportant experiments. Attempts were now
made to construct a machine by which the fluid should be accumulated in
greater abundance. In this Otto Guericke, the celebrated inventor of the air
pump was successful, and still more so Mr. Hawkesbee, whose treatise, pub-
lished in 1 709, was the first upon the subject, and the discoveries he made with
this improved machine, which was the first one made of glass, far exceeded
those of his predecessors. The science was from this stationary for thirty
years, when a Mr. Gray directed his attention to it, and arranged bodies into
two classes ; the first electrics, or those which like amber were capable of
being excited, and conductors, or those which not capable of excitation them-
selves, that is, thought at that time not to be so, yet allowed the fluid to pass
along them. Not long subsequent to this, M. du Fay, discovered the dif-
ference between what were then called vitreous and resinous electricity. He
taught that the phenomena of attraction and repulsion were occasioned by
two fluids distinct from and mutually opposed to each other. From this time
electricity became more studied, though not popular till the discovery of the
Leyden phial in 1746, when it spread rapidly over Europe, engaging equally
the attention of all classes of people. Dr. Franklin explained the mode of

3

acticn of the phial, and pubHshed his celebrated theory of there being but
one fluid, the diminution or redundancy of which he supposed to be the
cause of all electrical action. Soon the identity of the fluid with lightning
was boldly asserted and proved both by Dr. Franklin and L'abbe Nollet at
about the same period, the former venturing to bring down hghtning from
the clouds, and to perform with it all the experiments then known, thus
boldly setting the question at rest for ever. Lightning being thus satisfac-
torily accounted for, the transition to other meteoric phenomena was easy,
and in a very brief period the powerful agency of electricity in modifying the
surface of the earth, and the atmosphere around it, was firmly established.
Mechanical electricity, free electricity, the electricity of friction, the electricity
of tension, for by all these names this particular part of the subject is called,
could go no further ; but the wonderful discoveries made during the present
century of the intimate connexion between this science, galvanism and
magnetism, not only confirm our previous views, but induce us to attribute
the facts of all these difi'erent departments, as arising from one common
cause, and producing effects only so far varied as might be expected from
altered circumstances, and the difi'erent materials subjected to experiment.
The history of -this connexion or identity will lead us almost too far from our
immediate object ; we shall only observe that at the present time so much do
these subjects engage the attention of the scientific world, and so numerous
and unexpected are the discoveries made in them, that each year opens a
still wider field for electrical research, and the laws which regulate the
material world.

CHAP. I.

ELECTRICAL ACTION, EXCITATION, AND DIFFERENT STATES OF THE

ELECTRIC FLUID.

The electric fluid, though existing in every object around us, is, while in its natural state
of rest, not pei'ceptible to our senses ; but as soon as by any cause it is disturbed, that
which was before latent becomes free, and v/e are immediately sensible of its presence.
If violently agitated, the fluid itself becomes apparent ; if less moved, we are only con-
scious of the disturbance by the effects it produces in attracting towards it the light
substances around, and repelling them when by contact the fluid in those bodies also is
disturbed. The laws of this attraction and repulsion must form the subject of a futuio
consideration ; at present it will be more convenient to consider the nature of electrical
action, and call attention to a few of those common experiments, which show the uni-
versality of the electric fluid, and the numerous yet simple operations by which bodies
may be artificially excited, or thrown into a state of electrical action. However diversified
experiments on excitation may be, yet friction will be found to attend the whole of them,

and the more attentively the various phenomena are noted, the better founded must be the
conviction that this alone causes electrical disturbance. The eflfect will be in a great
measure accordant with the degree of friction employed, and with the dissimilarity of the
bodies acted upon ; and although it will be seen from some of the illustrations, that
evaporation and change of temperature of certain substances causes them to appear
electrical, yet each of these operations is attended by a motion of the particles among
themselves and against the containing vessel ; thus here, as in more obvious instances,
friction is produced, though by natural means, rather than by that mechanical rubbing
which we are accustomed to employ. The conclusion to which we must come, that friction
is the ultimate cause of excitation, is impressed the more strongly upon us by the circum-
stance that all those bodies which become electrical by heating, cooling, crystallization, or
other change of form or temperature, are still more easily and more powerfully excited by
the rubbing which effects other bodies.

In performing electrical experiments of any kind it must always be borne in mind
that the earth is the grand reservoir of the electric fluid ; from the earth it must at all
times be taken, and to be retahied even for a single moment it must be prevented
returning to the earth again ; this is easily accomplished by the application of the different
properties of electrics and conductors. The first of these classes of bodies may be excited
readily, but will not suffer the fluid to pass along them ; the conductors on the contrary
are excited with difficulty, but suffer the fluid to escape over their surfaces with great
rapidity of motion. Be it observed also, that the electric fluid takes every opportunity to
return to a state of rest and quietude, and to keep it disturbed, the body in which it is
excited must be insulated, or supported by electrics, and no conducting substance brought
within its sphere of attraction. In some of the following experiments, indeed in most
of them, we witness an electrical action only in one of the bodies subjected to friction,
while the rubber or other body is not considered. This however is equally acted upon,
and if we take proper means for detecting the electricity of both the rubber and substance
rubbed, we shall find that the action is the same in amount in both, but the nature of the
action is contrary in the rubber to what it is in the substance rubbed — one exhibiting what
is called a redundancy, and which is therefore said to be electrified plus or positively/ ;
the other having a proportionate deficiency, or is said to be electrified minus or negatively.
These two degrees or contrarieties of effect neutralize each other, and thus when two bodies
are rubbed together while they remain in contact with each other, no action is apparent ;
but when that contact is separated, visible effects take i)lace. Tliese preliminary remarks
will render plainer the annexed experiments.

Ex. 1. Attraction of amber. — Take a
piece of yellow amber, warm it, rub it briskly
on the coat sleeve, and hold it towards some
scraps of bran, filaments of feathers, or other
light bodies lying upon a book or a smooth
table. The amber being excited by the fric-
tion will attract the particles of bran, &c.,
and hold them suspended. This is the first
electrical experiment recorded. The workers
in amber are so annoyed by its strong at-
tractive, and easily excitable nature, as to
have the tips of their fingers often very greatly
affected by it.

2. Attraction of sealing wax. — A simi-
lar effect takes place when a stick of sealing
wax is rubbed and presented to any light
matters ; they will as before rise up and cling
to it. If either the sealing wax or the amber
be held towards the bran, &c , before it 4S
rubbed, it will have no effect upon them.

Any thing dry and covered with sealing wax
answers the same purpose as sealing wax.
The best thing to use is the glass tube men-
tioned in Ex. 9, one half of it in length being
heated, and red sealing wax then rubbed on
it ; this will adhere and form a resinous tube.

3. Attraction of rubbed paper. — Take
two pieces of white paper, warm them at the
fire, place them upon each other on a table
or book, and rub strongly the upper paper
with a piece of India rubber ; the papers will
now be found strongly electrical, so as to ad-
here together with such force that it requires
some trouble to separate them, and when
separated and then made to appi'oach each
other again, they will immediately rush to-
gether a second time.

4. Adhesion of brown paper to a wall.
— Take a piece of common brown paper
about the size of an octavo book, hold it
before the fire till quite dry and hot, draw it
briskly between the side of the coat and the
sleeve several times, so as to rub it on both
sides at once by the woollen. The paper will
now be found so powerfully electrical, that if
placed against a wainscot, or the papered wall
of a room, it will remain there for some
minutes without falling.

5. Adhesion of a feather to excited paper.
— If while the paper remain fixed to the wall
a light fleecy feather be placed against it, it
will adhere to the paper in the same way as
the paper adheres to the wall.

6. Glass plate excited. — Support a pane
of glass, (first warmed) upon two books, one
at each end — place some bran underneath it,
and rub the upper side with a warm black silk
handkerchief or a piece of flannel — the bran
will now fly and dance up and down with
much rapidity.

This experiment is the only contribution
that Sir I. Newton made to electricity, but
it was important, inasmuch as it proved what
was unknown before, that glass showed elec-
trical effects on the side contrary to that which
was excited. The account was read to the
Royal Society in 1675. It is very interesting.
" Having laid upon the table a round piece
of glass, about 2 inches broad, in a brass
ring, so that the glass might be i of an inch
from the table, and then rubbing the glass
briskly with the corner of his silk cloak, little
fragments of paper laid on the table under the
glass began to be attracted, and move nimbly
to and fro ; after he had done rubbing the
glass the papers would continue a consider-
able time in various motions ; sometimes
leaping up to the glass, and resting there
awhile ; then leaping down and resting there ;
then leaping up and down again ; and this
sometimes in lines seemingly perpendicular to
the table ; sometimes in oblique ones ; some-
times also leaping up in one arch, and leaping
down in another, divers times together, with-
out sensibly resting between; sometimes skip-
ping in a bow from one part of the glass to
another, without touching the tabl ; and
sometimes hanging by a corner, and turning

often about very nimbly as if they had been
carried about in the midst of a whirlwind,
and being otherwise variously moved, every
paper with a different motion. Upon his
sliding his finger on the upper side of
the glass, though neither the glass nor the
inclosed air below were moved, yet he ob-
served that the papers, as they hung under
the glass, would receive some new motion,
inclining this way or that, according as
he moved his finger.'' This is done much
better by a glass, 6 or 8 inches over, at the
distance of an inch from the table.

7. Coffee excited. — In grinding coffee,
particularly if it be fresh burnt, it will be
seen to cling around the lower part of the
mill, and also around the cup or basin held
to catch it — sometimes so strongly as to cover
the sides 2 inches or more above the general
surface.

These experiments are all examples of elec-
trical attraction, and some of them may be
made much more conspicuous to a public
audience, if the light matters to be attracted
are suspended in some manner, as for ex-
ample in the following instrument, which is

called a balance electroscope. Fix a glass
rod, a common phial, a stick of sealing wax,
or a slip of window glass upright upon a foot
or board, cement a needle point upwards upon
the top of this ; and upon the needle point
suspend an equally-balanced slip of very dry
wood cut as thin as possible, made perfectly
smooth, and about 8 inches long. At each
end of the wire fix a scrap of paper, or a
small ball made of cork, or the pith of elder.
To make one of these electroscopes or
electrical indicators, in the best manner, the
foot and supporter should be of brass, and
the balance of a fine glass thread ; the balls
being of pith, and covered with gold leaf.

Ex. 8. Attraction of electroscopes. —
Hold the excited sealing wax, amber, paper ,
ribbon or glass of these experiments towards
one of the balls of the balance electroscope,
the suspended filament of wood will turn
round on the pivot, so that the ball will follow
the excited matter held to it.

A. more delicate, and perhaps more con-
venient electroscope is
made as follows: — The
foot is of wood, the up-
right is a stout wire,
bent towards the top
as shown in the figure.
Upon the hook of this
are suspended two
pieces of sewing silk,
about 6 inches long
each, and which have
either small disks of
white paper, two pith
balls, or two feathers
tied at the ends. This
is called \X\e pendulum
electroscope. For the

above experiments one thread and feather is

sufficient.

9. Glass tube excited. — This is shown
much more conspicuously by using, instead
of the sealing wax, a glas-s tube about 2 feet
long, and an inch in diameter ; make this
perfectly dry and warm at the fire, then rub it
briskly with an old black silk handkerchief,
made warm. The glass will be powerfully
excited, and of course attract with great force
the suspended feather.

10. Desaguliers gives the following curious
experiments. He says, that when an excited
tube has repelled a feather, it will attract it
again, after being suddenly dipped into water,
in fair weather it will not attract it, unless it
hath been dipped pretty deep into the water,
a foot of its length in at least ; whereas in
moist weather an inch or two will suffice.
—Philos. Trans. Abr., vol. 8, p. 429.

11. The attraction of water by an excited
tube is shown by bringuig the tube to a stream
issuing from a condensing fountain, which
thereupon is evidently attracted to it. —
Desaguliers.

12. Recession of charged objects. — Hold
the glass tube in contact with the suspended
feather for a short time, the feather which at
first was attracted will soon become what is
called charged, that is filled with electrical
fluid. It will in this state become fleecy, the
filaments will diverge from each other, and
the feather j/?y away from the glass tube, and
most likely adhere to the wire support of the
electroscope. Sometimes if the tube be power-
fully excited, the feather will fly backwards
and forwards, giving a good example of elec-
trical attraction and repulsion.

Note. — It is here to be observed, that we
use the terms repelled, charged, filled with
electrical fluid, &c. in their popular sense
only, so also until we can consider more fully
the nature, effects and laws of electricity,
cannot enter into a discussion, whether there ,

be in reality no repulsion at all, or if there
be one electric fluid or two.

13. Repulsion of electrified feathers. —
Let there be two feathers suspended upon the
electroscope by different silk threads, they
will both adhere at first to the glass, and then
recede from it, and also from each other. If
there be three or more feathers, the same
effect will be exhibited.

14. Feather driven about the room. — If,
while still excited, a light fleecy feather be
brmgl t near, it will at first cling to the glass
rod, and afterwards fly away from it, and
may be driven about a room, by holding the
glass between it and any surrounding object.
If it should touch any thing not electrified,
it will fly back to the glass again. It will be
observed, that the same side of the feather
is always presented to the excited tube.

15. Electrified hair. — Another instance
of electric repulsion is seen when a bunch of
long hair is combed before a fire, '* each par-
ticular hair will stand on end," and get as
far as possible from its neighbour.

The above experiments show the electric
disturbance of various bodies, so as to inform
us that some power exists which is called into
action by friction, assisted by perfect dryness
of the materials employed, but they do not
communicate any intelligence of what this
power really is ; yet a very trifling increase of
the intensity of any of the foregoing will
render the fluid itself perceptible to our cor-
poreal senses, sight, hearing, feeling, smelling,
and as we shall show hereafter taste also,
though we believe this cannot be made per-
ceptible by the simple means we are now
employing.

The ancients were quite unacquainted with
any other electric effect of amber, but that
recorded in the first experiment. Dr. Hall
discovered many other electric properties of
it, as recorded in Philo. Trans. Abr. ,Yo\.2,
He says —

16. "I found by gently i-ubbing a well
polished piece of amber with my hand in the
dark, that it produced a light ; whereupon I
got a pretty large piece of amber, which I
caused to be made long and taper, and drawing
it gently through my hand it afforded a con-
siderable light. I then used many kinds of
soft animal substances, and found that none
did so well as wool. And now new pheno-
mena presented themselves, for upon drawing
the piece of amber through the woollen cloth,
and squeezing it pretty hard with my hand,
a prodigious number of little cracklings were
heard, and every one of these produced a
little flash of light ; but when the amber was
drawn gently and lightly through the cloth,
it only produced a light, but no cracklings ;
but by holditig one's finger at a little distance

from the amber, a large crackling is produced
with a great flash of light, and what to me is
very surprising is, that upon its eruption it
striker, the finger very sensibly, wheresoever
applied, with a push or puflf like wind. The
crackling is full as loud as charcoal on fire,
and five or six cracklings or more, according
to the quickness of placing the finger, have
been produced from one single friction, light
always succeeding each of them. Now I make
no question, but upon using a longer and
larger piece of amber, both the cracklings
and light would be much greater, because I
never yet found any crackling from the head
of my cane, though it is a pretty large one.
This light and crackling seem in some degree
to resemble thunder and lightning." Dr. Hall
also states that light can be produced from
jet, sealing wax and the diamond.

17. Break a large lump of loaf sugar in the
dark, or pound it in a mortar, when it will
appear covered with a beautiful lambent blue
flame. When grocers are sawing up loaves
of sugar as samples, the dust is most lumi-
nous and beautiful.

18. The electric light and snapping ob-
tained from paper. — Excite a piece of brown
paper, after having made it quite hot before
the fire, as in Ea;. 4 ; make it adhere to the
wall in a dark room, and immediately tear it
from the wall, a light attended by a faint
snapping noise will arise. This is the elec-
tric spark.

19. '1 he same is very perceptible, if the two
pieces of white paper, excited as in Ea^.3, are
taken and torn asunder in the dark.

20. Electric light and odour obtained
from' quartz. — Rub or grate together two

round uncut stones of quartz, calcedony,
cornelian, &c., and a strong phosphoric light
and odour will be produced, showing another
peculiarity: viz., that the electric fluid is
perceptible to our sense of smelling.

21. The spark felt. — Support a round
plate of metal upon the top of a very dry wine
glass. Excite the brown paper as in Ea;. 4,
and place it on the metal plate ; if now you
hold your knuckle quickly to the metal plate,
a small but very perceptible spark will pass
from the metal to the hand, showing the fluid
is perceptible to the touch, and also that it
will pass from one body to another, for it is
the fluid from the excited paper, which passing
throagh the metal is felt by the hand.

22. Sensation of cobwebs. — Hold the ex-
cited glass tube close to the face, a sensation
like that of cobwebs spread over the face will
be immediately apparent, and the hair will be
sensibly moved at the near approach of the
tube.

23. Shock from a cat. — Take up in the

lap a black cat which has been lying for some
time before the fire ; hold it by one hand under
the throat, and with the other hand rub the
cat several times along the back. The hair
will soon become so excited, and overcharged
with the electric fluid, that a complete shock
may sometimes be felt, and generally a suc-
cession of small sparks. We need scarcely
observe, that Miss Pussey must be a con-
senting party. This experiment, as indeed
do all of an electrical nature, succeeds best
in frosty weather.

24. Metallic ball electrified. — Suspend
from the ceiling a metallic ball by a silk cord,
and touch it with the excited glass tube. This
(Dall will now attract the feathers or the balls
of the common electroscope in the same
manner as the glass rod itself does. This
shows that electricity is communicated fr(Mn
one body to another, as it is very evident that
the metallic ball became electrical by contact
with the tube.

The above experiments, and which show
the various effects of the electrical fluid, are
made with somewhat brisk and continued
friction, and therefore produce effects of suf-
ficient plainness and strength to be perceptible
to us without any instrument of superior de-
licacy. It will naturally be concluded, that
a less degree of friction will still produce
similar eff"ects, although they will be propor-
tionably less in amount. Indeed we shall
soon have occasion to show that the most
trivial actions we do, and the most casual
operations of nature, require only favorable
circumstances to make their electrical cha-
racter apparent. Among these circumstances,
the most important is, that we should perform
the expei'iments with care, and the second, that
the instruments we use to detect the disturb-
ance of the fluid should be of extreme deli-
cacy. These instruments are called electro-
scopes and electrometers. The first indicates
an apparatus which shows that a disturbance
has taken place in the fluid of an excited body,
as is the case with the pendulum and balance
electroscopes we have described, and the
other, (the electrometer) is capable of measur-
ing the exact amount of this disturbance. It
is necessary to describe one of each of these,
that we may see the efl'ects produced by other,
and less obvious, or at least less powerful
modes of excitation.

THE GOLD LEAF ELECTROSCOPE.

The gold leaf electrometer is made of two
forms, as shown in the following cut. In that
marked 1, and which is called from iti in-
ventor, Bennett's gold leaf electroscope con-
sists of a wooden foot, which supports a glass
tube about 2^ inches wide, and 5 long. This
has two slips of tin foil pasted i,a the opposite
sides as represented. The cyli ider is closed

8

at top by a brass cap, which fits tight round
the sides, but takes off and on, in order that
if the two slips of gold leaf which hang from
the middle of the cap in the inside should
become broken, tbey may be repaired. The
cap should not in any other case be removed.
The gold leaves are about 3i inches long, and
^ an inch wide ; they are best fastened on by
a little piece of flatted brass, soldered to the
inner side of the cap, and the leaves, attached
by gum water, gold size, paste, or any thing
similar. They should hang so as to touch each
other when not in an electrified state, and
when divergent, as shown in the cut, they
should approach to the slips of tin foil on the
glass. The cap has occasionally a point which
screws upon it, as shown ; this however is
never used, except in trying experiments
upon the electricity of the atmosphere.

Sausseur's gold leaf electroscope, which is
represented in fig. 2 of the above cut, differs
from the former in the manner in which the
gold leaves are insulated. The cap is a flat
plate, with a wire soldered beneath. The
gold leaves are soldered at the lower end of
the wire, and the whole wire is inclosed in a
glass tu.ie. The outer surface of this tube
is best covered with sealing wax, as the in-
sulation of resinous substances is much better
in damp weather than that of glass, which
rapidly attracts the moisture of the breath, or
of the apartment. The diameter of the glass
may be 4 inches, the height of it 8 inches.
The size of the plate at top from 2 to 4 inches,
as most convenient. The cap which incloses
the top of the glass, and into which the glass
tube is cemented, may be of wood or metal ;
the former is preferable.

A cheap and good substitute for the above
may be made of a common six-ounce phial,
a wire passing through the cork of it, having
the gold leaves within the phial, and a brass
ball or a bullet above. A lamp glass, also,
with a cork above and below, (ball and gold
leaves similarly arranged,) answers every

purpose, the bit of card also is of little
consequence ; and let it be remarked, once
for all, that whenever glass apparatus is em-
ployed, it must be kept perfectly dry, slightly
warm, and free from dust. Of so much con-
sequence is this, that should there have been
a failure in any of the simple experiments, it
most probably has arisen from neglect of this
precaution. There are numerous variations
of this instrument, according to the purposes
for which they are required. One of extreme
delicacy, though not so much so as that with
gold leaves, is made with two fine strips of
straw, suspended on little wire loops. Ano-
ther is furnished with two extremely delicate
silver wires, with small pith balls attached :
this is used chiefly for experiments upon the
electrical state of the atmosphere. This with
numerous other electroscopes wil be de-
scribed hereafter.

Note. — We would remind the young elec-
trician that the tvhole of his apparatus may
be made by himself with ordinary care, and
that he may do so with greater facility, we
will fully describe the various parts of each
instrument. Let him at all times remember
to round off all sharp edges and corners, and
to make the wood work smooth. Every thing
in glass, except plates, whether cylinders,
tubes, rods or handles, he may purchase at
per lb., at the glass works, Holland Street,
Blackfriars. Tinfoil may be cheapest bought
at a pewterer's. A maker of it lives in Brown's
Lane, Spitalfields, London. A roll 5 feet long,
and 10 inches wide, costs bd, or a smaller
roll 3^d. Tinfoil for electrical purposes may
be as thin as possible ; it is best put on to
wood or glass with common paste. When
silk is used, let it be always black, except
when otherwise specified. The best varnish
for electrical apparatus is copal varnish or shell
lac varnish ; and if they are required to be
ornamented with a colored varnish, let it be
by two or three coats of sealing wax dissolved
in spirits of wine, laid on with a small brush.
Both the shell lac varnish and the sealing wax
varnish are easily made by breaking the lac
or the wax in small pieces, putting it in a
phial with spirits of wine, brandy or whiskey,
enough to cover it, and then placing the phial
on the hob till the resinous substance is dis-
solved. These varnisljes dry in a few minutes,
but copal varnish tnkes two days. The mode
of action and degree of susceptibility of these
electrometers are shown by the following series
of experiments: —

25. Take tie paper which was before
experimented with, and after again exciting
it well, lay it upon a plate of tin, supported
by a dry wine glass. Immediately and sud-
denly apply the knuckle to the under surface
of the tin, and a spark will be felt. A better
substance than tin would be a round piece uf

9

wood 6 or 8 inches in diameter, ^ an inch
thick, rounded at the edges, and covered
neatly with tin foil, as by this means sharp
edges are avoided.

26. Suspend a pair of pith balls to the
under surface of the plate of tin or wood ;
place the excited paper upon it as before,
and observe that the pith balls will recede
from each other, or show electrical repulsion.
This then explains the mode of action of the
electroscope, and the appearance it presents.
In this experiment the disturbed fluid of the
paper acts upon the fluid of the metal plate,
and that upon the fluid in the pith balls. In
gold leaf electroscopes the fluid is in like man-
ner disturbed, and of course according to its
amount or degree of disturbance so will be
the greater or less divergence of the gold
leaves.

27. Hold near the above instrument any
of the excited bodies used before — such as the
paper, or the glass rod, and the nold leaves
will diverge to a considerable distance from
each other, and remain so for some time. A
well-excited glass tube will stimulate it at a
distance of 2 or 3 feet, and must not be brought
too rapidly close to it, or the gold leaves will
be rent to atoms by the violence of the action.

28. Brush the cap of the electroscope with
the feathery part of a quill, and the gold
leaves will instantly diverge.

29. Give the cap a blow or two with the
corner of a black silk handkerchief, previously
warmed, and the friction, small as it is, will
be found to have the same effect as before.

30. Take a knife, fvith a glass or ivory
handle, and cut some small pieces off a slip
of deal, so that they shall fall upon the cap
as before. Each piece carrying down with
it a portion of the fluid disturbed, will, in a
similar manner, aff'ect the instrument.

31. After playing a tune upon a violin
with a well- rosined bow, hold the bow towards
the cap of the electroscope, the gold leaves
will immediately diverge.

32. Sift some steel, brass, or other metal-
lic filings, upon the cap of the electroscope,
from out of a metallic sieve. The&e tilings
become electrical by the friction merely of
passing through the holes of the sieve, and
will consequently affect the gold leaves. The
same may be done with charcoal, putty pow-
der, black-lead, lime, and numeroas other
bo lies.

33. Let the metallic sieve out of which
they are sifted be held by a sealing wr-x or
dry glass handle. Sift some metallic powder
through it, but at a distance from the elec-
troscope ; then hold the sieve to the electro-
scope, that will be found to be excited ; and
if the means be taken which are explained

in the after-part of this chapter to ascertain
the nature of the exciteqaent, it will be found
that the sieve is in a contrary state to that of
the powder.

34. Bombazine excited hy rending. —
Warm a piece of this stuff" at the fire, or
any other kind of material formed of two
substances, such as woollen and silk, silk
and cotton, silk and hair, &c. ; when warm
and dry, draw out the various threads, of one
of the substances, and put them on the cap
of the electroscope; it will immediately be-
come aff"ected. The weavers of bombazine
are well aware of these electrical properties.

35. Melt some chocolate in an iron cup,
adding a few drops of olive oil ; place the cup
upon the top of the electroscope to cool, as
it cools, it will become electric, and show this
by the divergence of the gold leaves.

36. Clean a piece of dry glass with whiting,
and let the particles fall upon the top of the
electroscope, they will sensibly affect it. Dust
brushed off" a coat will generally aifect it in
like manner.

37. Break a stick of sealing wax in half,
and hold one of the broken ends towards the
cap, and the gold leaves will diverge.

38. Varnish a piece of glass ; when the
varnish is dry, scrape some of it off, letting
it fall upon the electroscope ; this also will
show a sensible eff'ect.

The student will perhaps desire to vary
these experiments, and being observant will
soon ascertain that there are apparent ano-
malies in the mode of action, or in the eff'ect
produced, for which he will, until such are
explained, be unable to account for.

39. For example, let him liold the glass
tube to the gold leaf electroscope, so as to
make the leaves diverge, but so as not to
touch it ; he will observe that immediately
he removes the exciting cause, the effect will
cease ; as the glass is withdrawn, the leaves
will collapse. Now let him touch the cap
with the excited glass, and then withdraw it.
The gold leaves will now continue to diverge,
and not collapse as before.

40. While they are thus divergent, let the
glass still excited be made to approach a
second time, the leaves will recede still farther
from each other than before.

In the former of these experiments the elec-
tricity is induced; that is, no electricity is
really communicated to the leaves, but the
approach of the excited electric has had suf-
ficient power to disturb the fluid of the whole
apparatus, and to drive it to the extremity
of the gold leaves ; they being both electrified
repel each other, but the effect is transient
only, and when the exciting cause is removed,
of course the effect ceases. In the latter

10

experiment, in which the exciter touches the
apparatus, it positively charges it with some
of its own fluid, and therefore it is in this
case not merely the extremity of the gold
leaves which become electric, but the whole
apparatus, and they being the only delicate
parts of it, show that it is so ; this then is an
instance of accumulated or communicated,
and not induced electricity. The next two
or three experiments open to us a new field
of inquiry.

41. Roll up a band of flannel, warm one
end of it at the fire, and hold it by the other.
Excite the sealing wax by the warmed end,
hold the excited wax to the gold leaf electro-
scope, and it will show the usual signs. Next
remove the wax and hold the flannel ; this
will also show that it is excited. Next hold
them both together towards the instrument,
and no effect will be apparent.

It is then evident that in every instance of
friction, as there must be two bodies rubbed
together, so both of them become equally
excited. In the one body the fluid accumu-
lates, and that body becomes positively elec-
trified ; the other is to an exactly equal degree
deprived of its fluid by the first, and it be-
comes electrified negatively, and these two
degrees of disturbance are such as exactly at
all times to destroy each other, as was proved
in one instance in the last experiment, where
the wax and flannel being held together pro-
duced no effect. Yet although this is known
to be the case, the general result of the
operation of presenting the flannel and the
wax is the same, the gold leaves were diver-
gent in both instances ; this is because two
bodies electrified, whether negatively or posi-
tively, repel each other. When the wax was
presented, as wax when rubbed by flannel
becomes negative, it attracts to itself the fluid
of the apparatus. This is collected near to
Uie wax, and the opposite end is consequently
deficient ; when the flannel is presented, as
that is positive, it drives the fluid of the ap-
paratus to as great a distance as it can, and
the gold leaves are consequently divergent
from excess of fluid. These eff"ects, though
apparently the same, may be proved to be
contrary to each other, as follows : —

42. Touch the cap with the excited wax,
so that the gold leaves are affected by com-
municated electricity, then bring the wax near
them a second time, and they will diverge
still npore, but bring instead of this the ex-
cited flannel towards them, and they will
collapse ; in fact, the fluid in the flannel being
of a contrary character has annulled the
effect of the wax.

43. Next, while the leaves are divergent
with negative electricity by the wax having
touched them, excite a glass tube and hold

it towards the instrument. The leaves will
collapse as in the last instance, showing that
the effect of the flannel in the last experi-
ment, is the same as that of the glass in this,
or that they are both electrified positively by
the friction that has been used.

44. Suppose that the glass tube in the last
experiment be rubbed by flannel, instead of
the silk handkerchief recommended in Ex. 9,
the effect would be the same, as may be tried ;
if so, the flannel with which it is rubbed must
be negative ; whereas, in the last experiment
the flannel was positive ; thus the same sub-
stance may be positively or negatively elec-
trified, according to circumstances.

45. Try an experiment similar to Ex. 44
with a glass tube, rubbed with a black cat's
skin, and the glass is then negative, and the
skin positive.

46. Roughen the glass, and rub it with
silk, and the rough glass is then negative,
and the silk positive.

47. Rub the sealing wax with a piece of
tinfoil held tightly in the hand, and upon
trying the effect, the wax will now be found
positive, although in all our former experi-
ments it has been negative.

It is important then to observe, that
no body has any peculiar character of fluid
inherent in it. Glass and sealing wax only
show their ordinary effect under ordinary
circumstances, each as we have seen takes the
place of the other occasionally ; this however
was not suspected at first. M. Du Fay,
who ascertained the negative character of the
latter, and the positive character of the glass,
imagined that these effects were constant, so
much so as to designate the two states of
negative and positive, by the terms resinous
and vitreous ; supposing, and in which he
has had many followers in our day, that there
were two distinct fluids, the disturbance of
which was at all times simultaneous and equal.
It was not till the experiments of Mr. Canton
in the latter part of the year 1753, and of
Mr. Wilson soon afterwards, that showed the
impropriety of the terms vitreous and re-
sinous, though they were not able to affect
the question of whether there is one fluid or
two.

These experiments may be varied without
end, and we have by them a ready means of
ascertaining at all times the electric properties
of all substances which will admit of friction ;
for we have only to electrify any electroscope
with one substance, the effects of which we
are certain, and we can by that test all others.

48. Excite a glass tube, let it touch an
insulated body, for example, the balls of the
pendulum electroscope, and then hold the
body to be tested close to it, if the bali»

n

recede still more when electrified by this body,
it is electrified positively, and if they col-
lapse, it is electrified negatively. The two
states of the fluid may also be shown, as
follows : —

49. Excite a rod of sealing wax, and ano-
ther of glass, both by flannel. Hold them one
on each side of a pith ball suspended by silk,
the ball will vibrate backwards and forwards
from one to the other. The moving body
may be made in the shape of a fly or spider.

In all the above experiments it must be
observed, that the excited body to be tested
must be held towards the same part of the
apparatus as the test object was, or the result
will be indecisive, and may even appear con-
trary to what it is in reality. As before ob-
served, when an excited glass tube is held to
the electroscope, if it do not touch it, it
drives the fluid to the farther extremity,
which extremity is the part that shows the
positive effect. If it be held towards that
extremity, immediately the eff"ect may cease,
because it drives that redundancy to the other
end. This curious effect may be tried thus : —

50. Make a pendulum electroscope with a
glass support, and linen threads instead of
silk ones, or what will do as well, damp the
silk threads with the mouth, touch the top of
the strings with the excited tube, and the balls
will diverge, the fluid being driven to them ;
then present the tube a second time also at
the top, and they will diverge still more ;
hold it sideways towards them, and although
they will approach the tube, their divergence
will be but little altered. Hold the tube
beneath them, and they will collapse. The
effect of the induction now produced by the
tube being to repel the fluid towards the top,
and consequently away from where it shows
itself.

5 1 . Try the same experiment with an elec-
troscope made of the following shape ; the

cross arm being a metallic wire, the support
being glHSs. The excited glass tube being
»lli)we ! to touch the end A, and then being
withdrawn, both pairs of pith balls will show
signs of divergence. Hold the glass tube a
second time to the end A, but without touch-
ing it, the pair at A will partly collapse, while

that at B will diverge still more. Rcrcrse
the experiment by holding the excited glass
to B, and the balls at B will collapse, while
those at A will increase their divergence.

Instead of giving other experiments to this,
which necessarily have a great sameness in
their result, we have appended the following
table, taken from Cavallo^s Electricity, and
by the inspection of which the positive or
negative result of the friction of all ordinary
substances may be at once ascertained.

Cat Skin is rendered positive by friction
with every substance with which it has
hitherto been tried.

Smooth Glass is positive with every sub-
stance, except cat skin. (We believe
that this will hold good with several
other furs ; for example, that of a
black rabbit.)

Rough Glass '\s positiveviiih dry oiled silk,
sulphur and metals ; negative with
woollen cloth, quills, wood, paper,
sealing wax, white wax, and the human
hand.

Tourmalin is positive with amber, and
the blast of air from bellows ; negative
with diamonds and the human hand.

Hare's Skin is positive with metals, silk,
loadstone, leather, the hand, paper,
and baked wood ; negative with other
finer furs.

White Silk is positive with black silk,
metals, black cloth; negative with
the hand, paper, hair, and weasel's
skin.

Black Silk is positive with sealing wax ;
negative with hare's, weasel's, and
ferret's skin, the hand, brass, silver,
iron, and white silk.

Sealing Wax ispositive with some metals ;
negative with hare's, weasel's, and
ferret's skin, the hand, silk, leather,
woollen cloth, paper, and some metals.

Baked Wood is positive with silk ; negative
with flannel.

Mr.Singer justly remarks, that " the result
of experiments of this kind is much influenced
by the state of the bodies employed, and the
manner in which friction is applied to them.
In general, strong electric signs can only be
produced by the friction of dissimilar sub-
stances, but similar substances, when rubbed
together, so that the motion they individually
experience is unequal, are sometimes electri-
fied, and in such cases, the substance whose
friction is limited to the least extent of surface
is usually negntive ; thus the violin bow of
Ejc. 31, was positivo, while if the strings
had been alao tried, thev would have beeu

12

found negative." Another remarkable cir-
cumstance is that color makes a considerable
difference, black and white having in many
cases a contrary effect. The following curious
experiments on ribbons, stockings, &c., will
illustrate many of these effects ; —

52. Adhesive Ribbons. — Take two silk rib-
bons, one black, the other white, each about
3 feet long ; warm them at the fire, holding
them up flat against each otherwith one hand,
draw the thumb and fingers of the other hand
briskly over them several times ; they will
thus become powerfully excited, and although
the upper ends of the ribbons be forcibly
separated to the distance of a foot or more,
the lower ends will still cling together. The
black will be negative.

53. Instead of a black and white ribbon,
use two that are white, or two that are black ;
excite them in the same way, and they will
become repellant of each other, both being
positive if white, and negative if black.

54. Take a single ribbon, either white or
black, warm it, hold it by one end, while
another person holds the other end ; draw
backwards and forwards over it briskly any
negative electric, such as amber, sealing wax
or rosin. The ribbon will be excited posi-
tively, whether white or black. If instead of
being held at each end, it be laid upon a quire
of smooth dry paper, and then rubbed, the
effect will be the same. If positive electrics
be drawn over the ribbons, they will be ex-
cited negatively.

55. A strip of flannel and black ribbon
will excite, and show the same effect as two
differently colored ribbons.

56. Dry two white silk ribbons at the fire,
extend them on any smooth plane, draw the
edge of a short ivory rule over them several
times. While they continue on the plane,
they do not seem to have acquired any elec-
tricity ; yet, when taken up separately, they
are observed to be negatively electrified, and
repel each other. When they are separated
from each other, electric sparks may be some-
times perceived between them ; but when
they are again put on the plane, no electrical
appearances are seen without a second friction.

57. Place the ribbons on a 'rough con-
ducting substance, rub them as before, and
they will, on their separation, show contrary
electricities, which will also disappear when
they are joined together. The upper ribbon
is negative, the lower positive.

58. Place the white ribbons which have
been rubbed upon the rough surface, upon
that surface again after they have been se-
parated from it, and suffering them to remain
there a few minutes, they will then upon being
separated be found to attract each other ; tlie

uppermost being positivoly, the lowermost
negatively electrified.

59. When two ribbons are made to repel
each other, draw the point of a needle length-
ways down one of them, and they will rush
together.

60. Bring an electrified ribbon near a
small insulated metallic plate — it will be
attracted but feebly. Bring a finger near the
plate, a spark will be observed between them,
though both together show no signs of elec-
tricity ; on the separation of the ribbon they
again appear to be electrified, and a spark is
perceived between the plate and finger.

61. Lay a number of ribbons of the same
color upon a smooth conducting substance,
draw the ivory rule or paper knife over them,
take them up singly, and each will give a
spark where it is separated from the other.
The last will do the same with the conductor,
and they are all negatively electrified. Take
them from the plate together, and they will
all endeavour to recede from each other.

62. Let them be placed on a rough con-
ducting substance, and then be separated
singly, beginning with the lowermost, sparks
appear as before ; but all the ribbons will be
electrified positively, except the uppermost,
or that upon which the ivory knife has acted.
If they receive the friction upon the rough
conductor, and are all taken up at once, all
the intermediate ribbons acquire the elec-
tricity of the highest or lowest, according as
the separation is begun with the highest or
lowest.

63. If we take two ribbons of white silk,
cut from the same piece, and make them rub
against each other, while they cross at right
angles, the piece which crosses the other
transversely assumes negative electricity, and
the other becomes positive,

64. The same effect is sometimes produced
by rubbing two sticks of sealing wax, placed
at right angles with each other. It would
appear from these, and other experiments,
that the substance which is subjected to the
greatest friction becomes negative, and the
other positive.

Mr. Symmer, an electrician of the last
century, made some very curious observations
and experiments on silk stockings. He was
accustomed to wear two pair at the same
time, and from the refitiarks he made upo;i
taking them off and putting them on, th,5
following experiments are deduced : —

65. Electrified stockings. — Put upon the
same leg a worsted stocking, and over this a
silk one. Warm the leg at the fire, and rub
the hand over the stockings. This done, slip
off the siik stocking suddenly, and the two
sides of it will recede from each other, and

13

the whole retain the same shape as if the leg
still remained in it.

66. If the stockings are both of silk, the
one white and the other black, and they be
warmed, rubbed, and then pulled off toge-
ther, they will show no sign of electricity ;
but on pulling off the black one from the
white a crackling of sparks may be heard,
and a light may be perceived upon their
separation, if performed in the dark.

67. When the stockings are separated,
and held at a distance from each other, both
of them appear to be highly excited — the
white stocking positively, the black nega-
tively ; and while separated they are both
inflated, as in Ea;. 65.

68. If the stockings be of different colors
they will attract each other ; if of the same
color they will repel, in the same way as the
ribbons of former experiments.

69. Let the stockings thus inflated by
different electricities be suffered to meet ;
the inflation immediately subsides, and they
stick together with considerable force, each
becoming quite flat. If they be again se-
parated they will be inflated almost as
strongly as at first.

70. Take a ribbon of hot paper, and draw
it backwards and forwards upon a dry linen
cloth, laid on the knee, and the paper will
always be negative.

71. If rubbed against a metal it will be-
come negative, unless the latter has received
a high degree of polish, when it will some-
times become positive.

72. "When paper is rubbed against white
silk it is generally negative, unless the silk
be very hot, when the paper often becomes
positive. With black silk it always becomes
positive, except the silk be worn thin, when
the paper is generally negative.

73. Draw a black or white silk ribbon
backwards and forwards over a piece of
metal, and it becomes negative, whether the
metal be polished or not.

74. Take a piece of silk cloth, and swing
it backwards and forwards in the air of a
dry room, and it will show signs of negative
electricity when held to the electrometer.

75. A ribbon of silk, paper, or linen,
rubbed against the skin of an animal still
covered with hair, will always become very
strongly and negatively excited.

CHAP. 11.

ELECTROMETERS. EXCITATION BY HEAT, PRESSURE, CONTACT,
CLEAVAGE, CHEMICAL ACTION, AND EVAPORATION.

It has been already observed, that friction is the cause of electrical disturbance, and that
its extent agrees mainly with the degree of friction employed ; thus there are many
operations in which friction is produced in a very small degree — these are, no less than
more obvious examples, proportionably productive of electrical appearances. The mere
contact of substances, the separation of two bodies which are united, heating, cooling,
evaporation, impulse of steam, chemical actions, animal muscular motion, even the slow
vegetation of plants and seeds give out certain electrical signs ; nay, it is probable that
there is not an action we can do, or a change cf motion in an inanimate object we can
occasion, which does not in a greater or less degree disturb the electrical fluid, sometimes
exhibiting it in one character, and sometimes in another. Thus clouds drifting through the
atmosphere, the wind impinging upon the earth's surface, the rolling of the ocean upon the
shore, the rise and fall of dew, the occurrence of rain, hail, snow, and numerous other
phenomena of daily occurrence do, in their immensity, produce often well-known effects.
These are apparent to us when insulated as in our ordinary experiments ; in othci* cases

14

though equally produced, yet not observable, because of the want of those circum-
stances, which would have prevented these sudden effects from being as suddenly dissolved.
We can however show by our contrivances, that these electrical disturbances must take
place in all cases, even where the most minute substances are concerned, and where the
degree of friction is so small that it can scarcely be estimated.

The experiments of Coulomb, and others of later date, upon this electricity of
pressure, contact, &c., are very interesting and varied; many of these can be well shown
by the foregoing electroscopes ; but there are others of them of too delicate a nature to
show their effects to even the most susceptible of the instruments we have hitherto de-
scribed ; indeed, many of them would never have been witnessed at all, unless Coulomb
had contrived an electrometer which could be acted upon by less powerful impulses than
those we have hitherto found it necessary to depict or describe. The following is the most
delicate instrument of the kind : — It is called

COULOMB S TORTION ELECTROMETER.

It consists of a glass vessel, about the
diameter of a common tumbler, and 6 or 8
inches high ; such glasses
are made for the use of the
confectioners. We have
represented it as made of
a common pint decanter,
as that will answer the
purpose well, as would
also a wine bottle, or large
phial. Through the top
passes an untwisted raw
silk thread, 4 inches long.
The glass decanter is gra-
duated at the top by a
piece of card fastened on to a cork ; the card
is graduated to 360°, and the cork which fits
the decanter has a hole cut through it suffi-
ciently large for the silk thread to pass
through it, and to have, at all times, sufficient
room to vi^ork without touching the sides of
the hole. There is a little hand on the upper
end of the filament of silk, and at the lower
end a very fine gum lac or red sealing wax
thread, having at each extremity a small knob.
This lac needle and its knobs weighs only i
grain. A small hole is drilled in the side of
the vessel at A, through which passes a fine
wire, terminated at both ends with small balls.
It is cemented in the side of the glass by
sealing wax. When an excited body is made
to touch the knob at A, the knob at the other
extremity will acquire the same electricity as
the excited body. This electricity it will com-
municate to the knob of the lac needle, sus-
pended by the silk thread, which was previ-
ously almost in contact, and the two knobs
will repel each other. The moveable knob
will therefore be repelled from that which is
fixed, and the quantity of electricity will be
proportionate to the distance to which it is
duiven. By means of the micrometer at top,
It may be set at atiy position, so as in other

cases to show the degree of attractive force.
The following instrument, called Coulomb's
electrical balance, is made upon precisely
the same principle, and is of great delicacy.

coulomb's electrical balance.

A is a glass vessel, fitted into a stand at
the foot, and having a circular portion of its
circumference graduated.
Upon A is fixed a long
glass tube B, at the top of
which is a circular scale of
ivory C, with a small hand
moveable around the cen-
tre. Upon the centre of
motion of this hand is sus-
pended a single untwisted
fibre of silk, which passes
down the tube B, and into
the vessel A, where it is
terminated by a small piece
of straw D, across which
passes a wire and light ball
E, forming a balance ; also
through the top of A passes
th'j wire F, which has a ball
at each end ; one then of
course will be without the
vessel A, and the other within it, and exactly
opposite to the ball E. When the upper ball
F is electrified, it acts upon the ball E,
repelling this to a certain distance, which
distance, and consequently the degree of elec-
trization, is indicated by the graduated scale
on the side of A.

These instruments are superior for delicate
experiments to those electroscopes formerly
described, because the degree of tortion which
they undergo is a true criterion of the power
exhibited, whereas in the pendulum electro-
scopes gavitation acts very differentiy upon
them at difftrsnt degrees of divergence of the
leaves, so that a repulsion of the leaves of

15

gold leaf, of the pith balls, feathers, &c., as
the case may be, of 40°, does not necessarily
imply a double impulse to that action which
shows 20° ; on the contrary, it will be much
more than this. The balance electroscope,
(page 5,) is not so unequally influenced by
gravitation, but is too rude an instrument for
some of the very minute experiments which
the student would sometimes find it requisite
to perform.

The manner in which the state of the elec-
tricity, whether positive or negative, is dis-
covered by the tortion electrometer, is by
exciting it by a known body, as glass, and
then observing if the ball be attracted or re-
pelled by the approach or contact of the
substance to be tried.

Other instruments of extreme delicacy, and
which we shall find it for the future sometimes
convenient to use, are Volta's condenser and
BennetVs electrical doubler. We will pre-
viously to describing them show the principle
upon which they depend. When an insulated
conductor is opposed to one which is not in-
sulated, it has its capacity of electrical change
increased by that proximity, and is more sus-
ceptible of an increased or diminislied. quan-
tity of electric fluid than when freely insulated,
because in the state of approximation a much
more considerable charge will be required to
produce the same intensity, or tendency to
equilibrium. Now, were the contiguity of
the opposed plates permanent, no advantage
would be obtained ; for the principle which
renders the insulated plate susceptible of more
extensive electrical change, also prevents it
from rendering that change evident ; it is
therefore essential, that the plates should be
80 arranged as to admit of alternate proximity
and separation ; for example —

Suppose the metal plate B be suspended
by a wire A, and A itself suspended by two
silk threads. Also, suppose that C is a second
metallic plate phcrd u little below B, and that
B is connected with the ground. Touch A
with the excited glass rod, it will of course
communicate a charge to B. If now the plate
C be made to approach B gradually, yet not
so close as to take a spark, it will influence
the fluid in B to such an extent as to enable |
B to take a greater charge than before ; and 1

the nearer C is brought to B, provided no
spark pass between them, the greater will be
the effect of C approach. Now touch A a
second time ; this new fluid will act still more
upon that in C, and as action and reaction are
equal, B will be acted upon a second time,
and so on for several times. By this means
B will be soon charged to a very much greater
extent than it would have been if C had not
been present, and an impulse, not sufficient
to affect the gold leaf electroscope singly,
may thus be made perceptible. The following
instrument,

volta's condenser,
Shows a pair of these condensing plates
attached to a gold leaf electroscope. The
plate A is connected with the cap, and is of
course insulated. The plate B is supported
upon glass, but is connected with the ground
by the chain ; it turns upon a joint at C. It
is sometimes connected with another con-
denser, when the plate B becomes insulated
by taking off the chain. The two plates have
a thin coat of gum lac varnish on their inner
sides, to prevent contact, and in consequence
entire dispersion. To use the instrument,
touch the cap or plate A with the excited body,
B being withdrawn, then approach B to A,
and touch A again ; it may afterwards be made
to touch a third or fourth time, or more, until
the gold leaves show signs of divergence.

B

m

f

\lm

m

i

1

j

i

CI

^ ^

{

.

BENNETT S ELECTRICAL DOUBLER.

This instrument is an improvement upon
Volta'sj it being mare susceptible. It con-
sists, as the cut represents,
of a simple gold leaf elec-
trometer, the top of which
is a flat metallic plate,
marked A, of a simi'ar
plate B, which has a glass
handle, and of a third plate
C, also with a glass handle.
The plates C and B are
covered on their under-side
with sealing wax varnish.
To use the instrument, first
put the plate B upon A,
touch the plate B with the
finger, and then before the

lb-

finger is removed, touch the plate A with the
object to be tested. Take away the object,
and also the finger ; take up B by its handle.
Place C on B, and touch C with the finger.
By this a portion of the electric fluid is dis-
turbed in C, so that C becomes electrified
plus, or minus, in the same manner as A.
Place B upon A, and touch B with the
finger, and apply the edge of C to A ; the
electricity of C will then flow to A. Remove
C, take the finger from B, and raise B from
A. Proceed in the same manner for three
or four times more, until so much electricity
is accumulated in A, as to occasion the di-
vergence of the gold leaves. We will now
show the use of these instruments by ex-
periments.

The mode chosen by M. Becquerel to show
most of the following experiments was to
form the substances to be tried into small
discs, about one-tenth of an inch thick ; to
fix each to a varnished glass rod by way of
handle ; to take one of these handles in
each hand, and squeeze the two discs together.
After separating them, each disc has to be
presented to a delicate electrometer ; a single
pressure is often sufficient to repel the small
disc of Coulomb's tortion electrometer, but
by repeating the contacts Dr. Thompson
gays any electrometer may be aflfected.

ELECTRICITY BY PRESSURE.

Ex. 76. Pressure of Iceland spar. — Hauy
directs us to press in the hand a piece of
Iceland spar ; then by holding it to the
electrometer we shall find it electrical even
by this very minute amount of friction.

77. Pressure of other stones. — The same
may be done with the topaz, cnclase, arrago-
nite, fluor spar, carbonate of lead, and rock
crystal.

78. Pressure of glass. — Press two plates
of glass together, and examine them ; one
will be found positively, the other negatively
electrified.

79. Pressure of metal. M. Libes fixed

an insulating handle to a metal disc, and
pressed it, holding it by the handle against a
pitce of gummed taffeta ; the taffeta acquired
positive electricity, and the metal disc nega-
tive. The effect increases with the pressure,
but it ceases altogether as soon as the tatleta
loses its glutinosity, which renders it easily
compressible.

80. Pressure of cork. — Take two discs ;
one of cork, the other of caoutchouc. After
pressing them together the cork will be posi-
tive, the caoutchouc negative.

81. When cork is pressed against the skin
of an orange it becomes positive, and the
orange skin negative.

82. Cork pressed against Iceland spar,
sulphate of lime, sulphate of barytes, or
fluor spar, becomes negative, while with
cyanite, pit coal, amber, copper, zinc, and
silver, it becomes positive, and the substance
pressed against it of the contrary character.

83. Insulated cork pressed against any
part of the animal body, provided it be not
moist, receives an access of negative elec-
tricity.

Note. — It is not necessary that the bodies
pressed against each other should be of con-
trary natures. When two discs composed of
the same materials, as skin, amadou, &c. are
pressed against each other, they upon sepa-
ration exhibit diflerent states, as indeed might
be expected from the analogous experiments
of the ribbons, Ex. 52. It is often however
necessary to heat one of the two similar
bodies to render the effect more apparent.
The greatest effect is seen when one of the
substances is of an elastic nature. The better
conductors they are, the more rapidly the
bodies pressed together should be separated.

84. Electricity affected by heat. —
Take a piece of well dried cork, and cut it
in two, by means of a very sharp knife, and
then press the two cut surfaces against each
other ; it frequently happens, that however
hard the pressure may be, and however rapidly
we separate the two surfaces, neither exhibits
any signs of electricity after the parting. But
if we slightly heat one of the pieces of cork,
by holding it near the flame of a candle, and
renew the pressure, we shall find each surface
possessed of a different kind of electricity.

85. Heat and contact. — Take two pieces
of Iceland spar, press them against each
other ; no effect will be apparent, but if you
then warm one of the pieces, and renew the
pressure, a very evident excitation will be
apparent.

86. Contact of metals. — When zinc is
brought into contact with copper or silver,
and again separated by means of an insulating
handle, the zinc is found positive, and the
copper or silver negative. The experiment
is to be done thus : — Procure two circular
plates, about 4 inches diameter, the one of
copper, and the other of zinc, perfectly clean
and bright. Let an insulating handle be
screwed into the centre of each plate ; hold
the plates by their insulating handles, and
apply their flat surfaces together, suffering
them to remain in contact about a second ;
then separate them, and touch the insulated
plate of the condenser with the copper.
Bring the zinc and copper in contact with
each other again ; then touch the condenser
as before with the copper — repeat the opera-
tion till signs of electricity are apparent by
the divergence of the gold leaves. This ex-

17

periment requires very great care, and even
with that will sometimes scarcely be satis-
factory m tha result. If iron or manganese,
or even plumbago, be substituted for the zinc
plate, the result is the same ; but if gold or
platinum are employed no electrical action
takes place, from which IM. de Rive inferred
that these and similar effects resulted from
chemical action, and not pressure or contact ;
in this case the experiment, and others which
follow, belong to galvanism, and not free
electricity. It is still a disputed point with
philosophers. We shall presently show that
they really belong to the part of the science
we are now considering.

87. Contact of powders. — Have a tin,
zinc, or copper disc, 3 inches over, with an
insulating handle. Spread out upon a smooth
sheet of white paper any of the following
substances, quite dry ; succinic, citric, oxalic,
benzoic or boracic acid^ sulphur, silex, alu-
mine, carbonate of ammonia or resin. Touch
the powder with the plate of metal, and apply
the latter to the electrometer, v/hen after
several contacts electrical signs will be ap-
parent; the copper being in every instance
positive. With the following powders it is
negative, the alkalies and their carbonates,
the earths, except silex and alumine.

This and similar experiments show the near
approach of those two divisions of science,
di>tinguished as electrical and galvanic ; the
latter being always attended, if not caused, by
some chemical change, the former being as
fur as we have hitherto been able to detect in
cases of a similar character to this ; namely,
when two dissimilar metals being operated
upon at the same time are accompanied by
any such alteration of properties. Yet we
find in other cases that electrical and chemical
effects are concomitant, but these are in cir-
cumstances totally different from that of the
mere contact of the bodies which we are now
considering. In a galvanic circuit of metals
moisture is necessary for full effect ; in an
electrical circuit they, and every other part of
the apparatus, should be perfectly dry ; we may
also observe the following essential differences.

In electrical experiments we see atti-action
and repulsion take place between the bodies
excited ; in galvanism there is nothing of the
kind a})parent. Electricity has very little
effect in causing chemical decomposition —
galvanism does this by the simplest combi-
nations. The strongest power of electricity
has little effect upon a magnet, or to form
one, whereas galvanism is immediately shown
in its extraordinary connexion with mag-
netism. Thus clear distinctions between the
two sciences, or two divisions of the science,
are at once apparent, and serve as criteria to
arrange doubtful experiments, such as those
which follow.

' This tTeing premised, the explanation '>f the
following very curious instruments will be
easily understood, from what has been said
of the condenser and doubler. Suppose two
dissimilar metals, as copper and zinc, are
placed in contact with each otner, electricity
is excited ; one metal becomes positive, the
other negative — the copper will be negative,
the zinc positive. Suppose we place three
pairs of such metals, the three pairs having
their copper sides in the same direction ; each
copper in connexion with its zinc, but the re-
spective pairs varnished on the outside. Each
pair becomes excited by the mere contact,
and when they approach each other induction
takes place, as we explained in describing the
condenser, and the pairs act upon each other
by mutual approach. The varnish prevents
their coming into actual contact, and there-
fore the effect is not dissipated, from the vai-
nish being a non-conductor. The effect of
each pair is very minute, but when the pairs
of plates are multiplied to 1000 or more,
the result becomes powerful and decided.
These views induced De Luc to contrive an
apparatus, which he called his dry pile, the
effects of which are to a very great extent
proportionate to the number of plates, or
rather pairs of plates. The best account of
this, and two or three similar instruments,
is given by Mr. Singer, who himself made
many experiments with dry piles of different
extent and materials. These we will describe
in Mr. Singer's own words.

DRY PILE OR ELECTRIC COLUMN.

Mr. Singer says, " The materials I prefer
for these piles are thin plates of flatted zinc,
alternating with writing or smooth cartridge
paper, and silver leaf. The silver leaf is first
laid on paper, so as to form silvered paper,
which is afterwards cut into small round
plates by means of a hollow punch. In the
same way an equal number of plates are cut
from thin flatted zinc, and from common
writing or cartridge paper. These plates are
then arranged in the order of zinc, paper,
silvered paper with the silver side upwards ;
zinc upon this silver, then paper, and again
silvered paper with the silvered side up-
wards ; and so on — the silver being in con-
tact with zinc throughout, and each pair of
zinc and silvered plates separated from the
next pair by two discs of paper. An ex-
tensive arrangement of this kind may be
placed between three thin glass rods, covered
with sealing wax, and secured in a triangle,
by being cemented at each end into three
equidistant holes in a round piece of wood,
or the plates may be introduced into a glass
tube, previously well dried, and having its
end covered with sealing wax, and capped
with brass ; one of the brass caps may be

18

cemented on before the plates are Introduced
into the tube, and the other afterwards ;
eaoh cap should have a screw pass through
its centre, which terminates in a hook out-
side." This screw serves to press the plutefi
closer together, and to secure a perfect me-
tallic contact with the extremities of the co-
lumn. The instrument constructed in this
way is shown beneath : —

Ex. 88. If a column of about 1000 series
is placed horizontally, with each of its ex-
tremities resting on a gold leaf electroscope,
AS shown in the cut, the electroscopes will
each diverge ; that connected with the zinc
extremity of the column will be positive, that
connected with the upper or silver extremity
will be negative. If the column be very
powerful, the gold leaves of the electroscopes
will alternately strike the sides of the glass,
bat this motion is soon stopped by their
sticking to it.

THE PERPETUAL CHIME.

Soon after the invention of the column,
Mr. B. M. Foster discovered that when a
sufficiently -extensive series was put together,
its electric power was sufficient to produce a
sort of chime, by the motion of a small brass
ball between two balls, insulated and con-
nected with the opposite extremities of the
column. He constructed a series of 1500
pairs, and by its agency kept a little bell-
ringing apparatus in constant activity for a
considerable length of time. Mr. Singer
continues : *' I formed a series of from 12 to
1600 groups, which are arranged in two co-
lumns of equal length, which are separately
insulated in a vertical position ; the positive
end of one column is placed lowest, and the
negative end of the other — their upper ex-
tremities being connected by a wire they may
be considered as one continuous column. A
small bell is situated between each extremity
of the column and its insulating support ; a
brass ball is suspended by a thin thread of
raw silk, so as to hang midway between the
bells, and at a very small distance from each
of them. For this purpose the b

I connected, during the adjustment of the pen-
dulum, by a wire, that their attraction may
not interfere with it ; and when this wire is
removed, the motion of the pendulum com-
mences. The whole apparatus is placed upon
a circular mahogany base, in which a groove
is turned to receive the lower edge of a glasg
shade, with which the whole is covered."
An instrument of this kind it is supposed will
go for ever ; we have had one which has gone
for many months, and a friend of ours had
one of 1200 pairs of plates, which had been
goin^ three years when we saw it.

Mr. Singer directs, that in order to pre-
serve the power of the column, the two ends
should never be connected by a conducting
substance for any length of time. It is there-
fore necessary, when laid by, that it should be
placed upon two sticks of sealing wax, and
that the terminal balls be ^ an inch or so from
the table. And if a column which appears to
have lost its power be thus insulated for a
few days it will recover. There is another
cause of deterioration, which is more fatal ;
this is too much moisture — the paper discs
therefore should be made as hot as possible
before they are put together, or even sub-
jected to a continued but gentle heat for some
time before they are inclosed in the glass
tube, and that being heated also the plates
may be inclosed without the presence of any
appreciable quantity of moisture. The size
of the plates may be f of an inch in diameter,
or less. With a column of 20,000 plates, a
Leyden jar may be slightly charged, and
minute sparks seen between a wire brought
from the upper end, when it is made to
approach the lower end.

DE lug's iERIAL ELECTROSCOPE.

A name given to an instrument of the same
description as Mr. Singer's, intended to mark
the number of oscillations made in a given
time. For this purpose a single column of from
1 to 2000 series may be supported vertically

19

on an insulating pillar. A bent wire with a ball
at its lower end, is to be connected with the
upper extremity of the
column, so as to hang
parallel with, and be at
some distance from it ;
the ball at its lower
extremity being diame-
trically opposite to a
similar ball that is
screwed into the lower
cap of the column. To
the same cap is also
screwed a brass fork,
with a fine silver wire
stretched between its
extremities ; this is
placed above the ball, ^^^r^rirzrrs
and projects beyond the ^^'^H'T "^
brass ball of the column, so that when the
pendulum moves towards the ball it strikes
this wire first, and receives a kind of jerk
whi^h prevents it from sticking. The pen-
dulum consists of a gilt pith ball, suspended
by a very fine silver wire, which hangs pa-
rallel to the bent brass wire, to which it is
fastened at top. The arrangement is such,
that the gilt pith ball would be always in
contact with the brass ball that proceeds
from the upper extremity of the column, if
the apparatus had no electrical power, it
therefore always returns to this situation ;
when, after being attracted to the lower ex-
tremity of the column, it discharges its elec-
tricity by striking against the cross silver
wire.

sturgeon's perpetual motion.
We believe this has never been described,
but we remember that some years ago, Mr.
Sturgeon showed us an instrument similar in
its nature to the above of Mr. Singer's, but
of one metal only. He procured a common
box, about 6 inches square, and an inch deep ;
this was to hold the pile or collection of
metals. He used two kinds of zinc, one made
rough by dipping it into very dilute sulphu-
ric or nitric acid, or scouring it with sand
and water ; the other made as smooth as pos-
sible. These metals were very thin, and being
dried, were cut into pieces with scissars
roughly into squares about f of an inch
on the side ; they were then arranged in
rows in the box thus : — First, a piece of
smooth zinc, then one of rough zinc, then
three pieces of writing paper made hot in
the fire ; again smooth zinc, rough zinc,
and three pieces of paper, keeping the same
order till the pile was completed. There
were several rows which were laid backwards
and forwards along the box, the sides of the
rows not being allowed to touch each other,
but their ends being rightly united with a
piece of £inc reaching from one row to ano-

ther. Tlie two extreme ends had connected
with them an upright piece of brass, and a
pendulum so supported on a wooden or metal
stem, that it played from one to the other.
We write from recollection, when we give
1600 as the number of the pairs of plates.
The following shows an instrument of this
kind. We have made the poles to end in
bells, and covered the whole with a glass
shade, which appendage is necessary for all
these instruments, the currents of air having
a great effect in disturbing or even stopping
their motion.

ZAMBONl's PERPETUAL MOTION.

This is an instrument of the same kind as
the last, or as that of Singer. The only dif-
ference consisting in the form of the instru-
ment, and the material of the small plates. It
is represented thus : — D is a box, containing
a drawer ; on the centre of the top of the box
is a glass pillar, with a steel point at top, C.
Upon this rests a very light frame-work of
wire or wood, with six arms at the lower
part, upon each of which is suspended a
small strip of thin sheet brass or gold. The
drawer is filled with several raws of pieces
of paper, about an inch square each, altoge-
ther about 20,000 in number ; one side of
the paper is covered with silver leaf, the
other painted over with black oxyde of man-,
ganese, honey, and water. The papers ara
arranged so that they should form one con-
tinued series throughout. Pieces of tin-foil
unite the rows together. One end of this
pile is connected with the pole or brass stud,
A ; the other with the contrary pole, A.
The strips of metal hanging from the cross
arms, B B, strike one pole, and then proceed
to the other to deposit the electric fluid they
acquired by the first impulse. So in the ro-
tation the several strips are in like manner
affected, and the frame with its various arms
is in continued motion, which it will main-
tain for years. It is necessary that it should
be covered with a glass shade, to prevent tlie.
disturbance of wind, &c. These machines

20

often require to be set going with the finger
in the first instance, or by turning the glass
shade round to produce a slight current.

EXCITAT^JN BY CHEMICAL ACTION.

Ex. 89. Excitation of burning charr,{yal. —
Charcoal, when burnt, sometimes gives out
electricity ; at other times none at aU. It may
be tried as follows : — Support a brass plate
upon the top of a delicate e;':)ld leaf electro-
scope ; then take a cylirutrical piece of char-
coal, with flat ends, 2 inches high and 1 inch
in diameter. Place this piece of charcoal
vertically, 2 inches and 5, or 3 inches
below the brass plate. The charcoal com-
municates with the ground, and is to be
lighted at the centre of the upper end, taking
care that the fire does not reach the sides.
A current of carbonic acid rises, and strikes
against the plate, and in a few minutes the
electroscope will show signs of disturbance.
If the piece- of charcoal be so inclined that
the carbonic acid is obliged to slide up the
sides of the charcoal no effect is produced ;
this is a very delicate experiment, and may
require the aid of the condenser. The fol-
lowing shows the arrangement of the appa-
ratus : —

90. Electricity of burning hydrogen. —
The flame of hydrogen gives, at different

times, very different indications of electric
properties, but it may be made pretty steady
in its effects upon the electrometer by the
following method of Pouillet : — The hydro-
gen gas is made to flow out of a vertical ghiss
tube, the flame itself having a breadth of 4
or 5 lines, and a height of about 3 inches.
A coil of platinum wire is employed to con-
duct the electricity from the flame to the
condenser. When this coil is so much
larger than the flame, as to inclose it, and to
be distant from its external surface about
4 inches, signs of positive electricity make
their appearance. These signs become more
and more intense as the distance diminishes,
but when the coil becomes so small as to
touch the flame, the electrical signs become
weak and unceitain. Thus it appears that
round the flame of hydrogen there is a sort
of atmosphere, at least 4 inches in thickness,
which is always charged with positive elec-
tricity.

91. If a very small coil of platinum
wire b6 placed in the centre of the flame, ia
such a manner that it is enveloped on all
sides, and made to communicate with the con-
denser, that instrument becomes immediately
charged with negative electricity. Thus it
appears that the outside of the flame of hy-
drogen is always charged with positive elec-
tricity, and the inside with negative electricity.
It follows from this that there is a layer of
the flame where the electricity is insensible,
accordingly if we regulate the coil in such a
manner that it penetrates nearly one-half into
the brighter part of the flame all electrical
indications disappear. — Tliompson. Similar
experiments may be tried witii the flame of
alcohol, ether, wax, oils, fat and vegetable
bodies.

92. In a strong phial put a niixture of
oxygen and hydrogen gases, in the proportion
of 1 volume of the former to 2 of the latter ;
immerse in this quickly a slip of platinum,
fastened to the inside of a good cork which
fits the phial, holding the neck of the phial
downwards, while inserting the platinum,
and which should be made very oright pre-
viously by immersion in sulphuric acid, the
action of the platinum will be such, that the
gases will combine and form water, sometimes
with so much force, that their union will be
attended with an explosion, the }ilatinum
becoming red hot. This is an experiment of
Dr. Faraday. The same had been observed
before by Dobereiner, as to spongy or black
platinum, and is the only way in which to
account for the action of his lamp, in which
a stream of hydrogen thrown upon spongy
platinum heats this latter sufliciently to inflame
the gas. The platinum acts as a medium
to combine the hydrogen with the oxygen of
the air.

21

EXCITATION BY CHANGE OF TEMPERATURE.

This division of the subject forms what is
commonly called thermo-electricity, which
involves so many considerations distinct from
free electricity, that we cannot extend the
subject beyond the mere circumstances at-
tendant upon the electricity of the tourmalin,
and one or two other bodies. The tourmalin
was early known to exhibit attraction to light
bodies when warmed, and the early electri-
cians have recorded numerous appearances,
which this mineral exhibited when heated.
The most interesting of these are as follows,
previously observing that those tourmalins
only, whose ends are dissimilar to each other,
can be excited so as to show in a plain manner
the contrary effects of the two ends. Black
tourmalins seldom have electric properties.
There are two modes of exciting this stone,
namely slow and rapid heating and cooling,
and exceeding small alteration of temperature
is sufficient to render it electric.

Ex. 93. Let a tourmalin be equally heated
over all the surface, as for example, by dipping
it into boiling water; then hold it to an elec-
troscope, when the gold leaves will immedi-
ately diverge, one end exhibiting negative,
the other positive electricity, and will so
continue all the time of cooling.

94. Heat only one end of the tourmalin,
while the other is not altered in temperature,
one end will then exhibit electricity, while
the other will show no effect. To try this,
it may be previously fi^stened to a small stick
of sealing wax. This is a very singular ex-
periment, because it is an instance of one kind
of electricity being apparent without the
other.

95. Suspend a long crystal of tourmalin
upon a stick of wax. Heat one end and cool
the other at the same time, by touching one
ei:d with a piece of hot metal, and the other
with a piece of ice ; removing these heating
and cooling objects both ends of the tour-
malin will be found electrical.

96. To show these effects, M. Becquerel
employed the following apparatus, which
however is by no means necessary. The
tourmalin is placed in a slip of paper, sus-
pended horizontally within a glass cylinder,
by means of a single thread of raw silk ; this
cylinder reposes upon a metal plate, which
is heated by means of a spirit lamp beneath
it. In proportion as the inside of the cy-
linder becomes heated, the tourmalin becomes
electric, in consequence ot the elevation of its
temperature. If it now be drawn up, as shown
in the figure, until it is of the height of two
minute balls and wires connected with two
gold leaf electroscopes, upon applying the
ends of the heated tourmalin to each of these

alternately, both will be charged, one with
negative, and the other with positive elec-
tricity.

Ex. 97. Put a heated tourmalin on the cap
of an electroscope, and then let it cool. The
gold leaves will diverge, and if the upper
surface be connected by a bit of tin foil, or
a wire, with the cap of a second electroscope,
that also will diverge, with electricity of a
contrary character, as may be proved by
bringing them together, when the electricity
of the one %Yill destroy that of the other.

98. The electricity of each side, or of
both, may be reversed by heating or cooling
in contact with various substances, so if it is
cooled or heated in contact with the palm of
the hand, that side of it, which v.rould have
been positive if cooled in the open air is
now negative, and that which is now positive
would have been negative.

Most of the above properties have been
also observed of other stones, particularly of
boracite, axinite, mesotype, the silicate of
zinc, tapaz, sphene, calcareous spar, ame-
thyst, diamond, red and blue fluor spar,
garnet, and many other bodies, though it
appears probable that it is only in those
crystals which are irregular that such ap-
pearances can be noticed. In the melting
and cooling of sulphur there are several
analogous phenomena ; the nature of elec-
tricity depending upon the nature of the
vessel in which the experiments are con-
ducted.

99. The following experiment on the
electricity of heat is one of Mr. Canton. He
procured some thin glass balls, of about an
inch, and an inch and'^ in diameter, with
stems or tubes about 8 or 9 inches in
length, and electrified them, some positively
on the outside, others negatively, and then
sealed them hermetically ; soon after he ap-
plied the naked balls to his electrometer, and
could not observe the least sign of their being
electrical ; but holding them at the fire, at
the distance of 5 or 6 inches, they became
strongly electrical in a short time, and more
so when they were cooling. These balls would
every time they were heated give the electric
power to, or take it from other bodies, ac-

22

cording to the plus or -minus state of it within
them. Heating them frequently, diminished
their power, but keeping one of them under
water for a week, did not in the least impair
it. The balls retained their virtues above six
years. We have not tried this experiment.

THE SULPHUR CONE.

The apparatus by which this experiment is
done is made as follows : — Take a large ta-
pering wine glass, cover
a portion of the outside
tapering part with tin
foil ; twist a wire, as re-
presented, and upon the
end of it suspend two fine
pith balls by linen threads.
Having ready some melted
sulphur, and a thin glass
rod, pour the suphur into
the glass, and immerse
the glass rod into the
upper part as a handle ;
hold it there till con-
, then suffer i' *« ^^^^^^^ °^ itself —
when quite cold the apparatus is complete.
You must, however, be very particular that
a chain, wire, or som^ other conducting sub-
stance, connects the wire with the ground
during the cooling o^ ^^^ sulphur, or no
effect will be produced— that is if it has been
melted in a pipkin.

E,r. 100. Lift up by the glass handle, the
sulphur within the conical glass, and at the
the moment of separation, the pith balls will
diverge, or separate from each other. Let
the sulphur drop down again into the glass,
and this action of the balls will cease. Again
produce separation of contact, and they will
again diverge ; and thus, for a considerable
time, the alternate action will be kept up,
even indeed for days and weeks.

101. Melt some sulphur in an earthen ves-
sel, put it in a melted state to cool upon a
piece of metal ; it will upon separation be
found highly electrical, as may be proved by
holding it to an electroscope.

102. Pour some melted sulphur, which
has been heated in an earthen vessel, upon a
piece of smooth glass. Upon separation of
the sulphur, when cold, no electric ap-
pearances are perceptible.

103. Let sulphur be melted in a glass ves-
sel, and afterwards left to cool, they will both
acquire a strong electricity. The sulphur
negative, and the glass positive, whether
they be left to cool upon conductors or not.

104. Let melted sulphur be poured into a
cup of baked wood, it acquires a negative,
and the wood a positive electricity ; but if it
be poured into sulphur, or rough glass, it
acquires no sensible electricity.

EXCITATION BV CLEAVAGE

Ex; 105. Take a piece of dry talc, warm it,
then spht it rapidly ; hold one of the pieces to
the electroscope, the effect is herevery strong {
if the talc be split rapidly in the dark, a faint
phosphorescent light will appear between the
sides of it. ,

106. If we fix with mastic or shell lac an
insulating handle upon each of the faces of a
plate of mica, we may ascertain that each of
the slices separated is in a contrary state of
electricity ; the intensity of which increases
with the rapidity of the separation. Before
making these experiments we must well dry
the talc, and observe that it is not already
split.

107. Make a large card warm at the fire,
double it across, and tear it in half ; at the
part doubled each fragment will become
electrical, and the one in a contrary state to
the other.

EXCITATION BY EVAPORATION.

Ex. 108. Place upon the cap of a gold leaf
electroscope, a small tin dish or patty pan,
having in it a red hot coal just taken out of
the fire. Sprinkle upon the coal a few drops
of water — the evaporation of this will set the
gold leaves into considerable action. This
will not succeed with either charcoal or coke.
It does best with a hot iron put into the
water.

Volta, Lavoisier, La Place, and others,
state that water never changes its condition,
without electric effects being produced.
Others contend that this is not the case,
unless chemical change also accompanies the
action. The electricity of steam, a recent
discovery, and which we must defer the con-
sideration of for .some chapters, will throw
much light upon this subject.

23

CHAP. III.

ELECTRICS AND CONDUCTORS. ELECTROPHORUS. CAUSE OP
ELECTRICAL APPEARANCE.

The only experiments on electricity known to the ancients, were, as before observed, the
attractive powers of amber when rubbed ; and the very first set of electrical experiments
tried by the moderns was to discover if any, and what substances possessed the same
extraordinary properties. These experiments, and which were made by Dr. Gilbert early
in the seventeenth century, were the foundation of the science of eleetricity, as they
directed the attention of philosophers to the subject. Considering how universal a fluid
it is, and how easily excited, it must be a matter of surprise, that the discoveries of
Dr. Gilbert had not been some of them made long previously. In trying to elicit electric
properties from various bodies, this physician was successful only in certain cases, parti-
cularly in electrizing some stony materials ; and nearly a century passed before Dr. Grey,
Desaguliers, and others, renewed the subject with that energy which might have been
expected. The former of these gentlemen discovered that electricity might be communi-
cated to, and would pass along certain bodies, as for example, that it would pass along
hemp, but not along silk. Thus, that bodies were not possessed of the same characters
was evident. It was afterwards found that those bodies which could be excited by the
ordinary means then employed would not convey or conduct the fluid readily along them,
and, on the contrary, those which conducted the fluid, could not be excited. Hence arose
the two terms electrics and conductors. Both these terms are still retained in their
original sense, but the former of them is to be understood to include only those bodies
which show electric properties in ordinary circumstances when held in the hand, and which
do not require to be insulated previous to excitation ; for it will have been observed in
many of the preceding experiments, that conductors, as for example the metals, may, by
taking proper means, be no less excited than other bodies, as was shown in JBa?. 86, 79,
and 32, and which the next experiments will exhibit still more plainly. So that the term
electric is not quite accurate, although retained for the sake of convenience. These
electrical bodies are often called non-conductors, a term better in some respects than
electrics, though not in others, as we shall see that a body may be a conductor in one
condition, and a non-conductor in another.

It will be seen from the above, that a particular substance may be an electric in one
state, and a conductor in another ; thus glass and sulphur are both excellent electrics when
in masses, but when pulverized become imperfect conductors. So green wood is a con-
ductor ; baked wood a non-conductor ; baked still more into charcoal a conductor again ;
and when in the state of wood ashes a non-conductor once more. Many bodies also are
conductors merely because they contain water ; thus almost all highly-dried animal and
vegetable matters are non-conducting. Dried glue, parchment, bone, ivory, hair, feathers,
horn, tortoise-shell, wool, silk, gums, resins, wax, cotton, sugar, &c., &c., are electrios,
yet as soon as either of them becomes damp, a conducting property is communicated ;
hence the necessity of well drying electrical apparatus when in use ; and also the same
fact shows the reason that machines of this kind act so imperfectly in damp weather, or
in a room before a crowded audience, whose breath quickly settles in moisture upon the

24

various electrics around. Too great heat also impairs the insulating effect of glass, Sia
for although it will not in ordinary temperatures suffer the fluid to pass along its surface,
yet when heated to redness it becomes a good conductor; and so also is baked wood made
very hot, melted resin, hot air, &c.

Notwithstanding this, we for convenience sake divide all bodies into the two classes
of conductors and non-conductors, or electrics and non - electrics . the former parting
immediately with any fluid given to them, and the latter retaining it so as to be apparent
to the senses. Thus air is an electric or non-conductor — were it not so, electrical experi-
ments would be unknown, the fluid being dissipated as fast as it is accumulated ; water,
on the contrary, is a good conductor, hence the necessity of keeping the apparatus dry,
that the disturbed fluid may be retained. Metals are the best conductors, therefore we
use them for such parts of our electrical machines as are intended for the transit of the
accumulated fluid. Glass and silk are electrics, or non-conductors, consequently are
available as bodies to be excited, and as capable of preventing its escape and dispersion.
Thus of an electrical machine the connexion between the cushion and the earth is a
metallic chain or wire, to allow of the passage upwards of electricity, the glass cylinder
being rubbed sets it free, the brass or tin conductor collects it, and its glass support
insulates it, and thus prevents its escape to the earth again.

The following experiments show that metals
may be excited equally with those bodies or-
dinarily called electrics.

Ex. 109. Electrncity of quicksilver. — In-
close some quicksilver in a thin glass tube a
foot long, and of an inch in diameter. Make
the tube dry, cork it up, and shake the quick-
silver briskly from end to end. If now the
tube be held towards any electrometer or
electroscope, it will show itself powerfully
excited.

110. Put a small cup upon tne gold leaf
electroscope, and pour the quicksilver from
the tube into the cup, when the divergence of
the leaves will show the metal to be excited.
It may be considered doubtful if the metal be
here excited at all, or whether it be not the
glass alone excited, and have communicated
its electricity to the metal, but let it be re-
membered, that when two bodies are rubbed
together, they are both excited at the same
time, but in a contrary degree.

111. Let the two electroscopes, which were
used in the last experiment, one of which
was charged by the metal, the other by the
glass, be touched together ; the electricity
of them will not be destroyed, because we
have applied to one of them the outside of
the glass tube, whereas it was the inside that
was subjected to friction. The inside there
fore is in a contrary state to that of the
metal, and the outside in the same state as
the metal. The metal is negative — the inner
side of the glass positive, the outer side
iKgative, as may be tested in the usual way.

112. Luminous barometer. — Let the tube
which holds the mercury be exhausted of air,
and then shaken briskly up and down the
tube ; flashes of light will dart across the
tube. This, which is an experiment of
Mr. Hawksbee, may be done in a flask or
large phial, and without any great degree of
exhaustion ; even heating the vessel well,
and thereby rarifying the air, will often be
sufficient.

113. Put a gold leaf electroscope under a
tall open-topped receiver of an air pump.
Place a small wooden mercury cup to close
the top ot the receiver, pour a little mercury
in it, an.'l exhaust the air beneath ; as the
mercury filters through the cup it will become
excited, as will be seen when the drops fall
upon the electroscope.

114. Place a smooth round plate of metal
on a cake of rosin or shell lac, rub the metal
with a cat skin ; draw it up by a silk threid
previously attached to it, and it will be found
excited.

It will be evident that a knowledge of the
individual conducting powers of all sou-
stances is requisite to a rigiit understanding
of the first principles of the science, and
that even the simplest experiments may be
conducted wiih success. The following table
presents a series of conductors and electrics,
beginning with those which have the greatest
conducting power, and terminating with those
that have the least. The order in which
they possess tlie power of insulating is of
course the reverse of this ; that is to say,
the best or most perfect electrics are at ti o

25

bottom of the tabic. It may also be ob-
served, that the middle of the table exhibits
bodies almost neutral in their properties,
being but very imperfect conductors, or very
slight electrics : —

The most perfect or least oxidable metals.

The most oxidable metals.

Charcoal ; especially from hard wood.

Plumbago, or black lead.

The mineral acids.

Metallic salts and ores.

Water and other liquids ; and snow.

Living vegetables and animals.

Smoke, soot, and steam.

Rarified air and flame.

Dry earths and stones.

Pulverized glass.

Flowers of sulphur.

Dry metallic oxydes.
Oils.

Vegetable and animal ashes.

Ice; when cooled down to 13° Fah.

Phosphorus.

Lime, dry chalk, and mnrble.

Caoutchouc, camphor, and bitumen.

Silicious and argillaceous stones.

Porcelain.

Baked wood.

Dry atmospheric air and other gases.

White sugar and sugar candy.

Dry parchment and paper.

Cotton.

Feathers, hair, and silk.

Transparent gems.

Glass.

Fat.

Wax.

Sulphur.

Resins.

Amber and gum lac.

To discover if a body be an electric or not,
hold it against the conductor of a machine
when charged ; if a spark can now be taken
by the knuckle from another part of the
conductor, the substance under examination
is an electric ; if not it is a conductor. If
a liquid, a gas, or a powder is to be tried,
inclose it in a glass tube ; should the spark
not now pass it will be known to have been
conveyed away by the liquid, &c. under
trial.

The following experiments will illustrate
the foregoing remarks, and show the methods
of distinguishing the bodies which belong to
these two classes.

Ex. 115. Let a metallic cylinder be placed
upon silk lines, or upon dry glass ; bring an
excited glass tube so as to touch it, and every
part of the cylinder will attract and repel
light bodies as forcibly as the exciteil electric
itself, showing that metal is a conductor.

116. Sujiport a dry glass rod on silken
lines, bring an excited glass rod near it, and
no attraction or repulsion will take place,
showing that the glass rod is not a conductor.

117. If the glass rod of the last experiment
be wetted with water, it will show electric signs
in the same manner as the metal of Ex. 115,
but if with oil, very slight effects will be
communicated, showing water to be a good
conductor, but oil a very bad one.

118. While you try the Ex. 115, place a
lighted candle near to the metallic rod, and
the fluid which would otherwise be discover-
able in the metal will have been dissipated by
the flame and rarified air ; they are therefore
conductors ; yet it is evident, that air at its
usual temperature and pressure is a non-con-
ductor, otherwise few electrical appearances
of any kind could be observed, as the air
would dissipate or convey away the fluid
accumulated.

It will have been observed, that wherever
we have shown friction, there has also been
separation of contact ; and upon a strict ex-
amination it will be found, that although the
rubbing of two dissimilar bodies together
may, and does occasion the electric fluid to
be disturbed, yet it is only when these bodies
are held apart, that each is found to put on
electrical appearances. Thus in Ex. 4, the
brown paper is the one body, and the coat
the other. In Ex. 7, the coffee is the one
body, and the mill in which it is ground the
other ; so also in Ex. 15. The comb passing
over the hair must certainly be separated in
turn from those particular parts it touches in
its course along, and not till then is it seen
that those parts are electrical ; and thus in
every experiment there is not merely friction,
but separation of the parts rubbed together,
where it is not so, no electrical appearance
would be perceived, as is clearly proved by
Ex. 100, where electric effects were percep-
tible only when the sulphur was separated
from the glass. An experiment similar to
this is as follows : —

Ex. 119. Pour some melted sulphur into
a metal cap which is supported upon the
top of a gold leaf electroscope ; dip a glass
rod in it as a handle, and let it get cold ;
when quite cold, lift up the sulphur by the
handle, and the gold leaves will immediately
diverge, the cup itself being electrified, and
if the sulphur beheld to another electroscope,
that will be shown also to be excited. As
often as it is raised from the cup, the effects
become manifest, and when put down again
they cease.

120. Take a piece of glass, about 5 inches
long by 3 inches broad — warm it, wrap tin
foil all over it, and rub the outside of the
tin foil smartly with the hand. The glass

36

2G

thus excited, held to the cap of Bennett's
gold leaf electroscope, will not show any
electrical effect while it remains wrapped in
the tin foil, but if this be removed, and the
glass alone be presented, the gold leaves will
instantly diverge.

The same is exemplified in the electro-
phorus, an instrument which is described,
and may be made as follows :— Procure a
round piece of tin, about 10 inches over, and
have the edge of it turned up about i of an
inch, so as to be capable of holding some of
the following mixture ; (melted over a fire,)
1 pound of yellow rosin, and 2 ounces of
wax. This being poured into it, and suffered
to cool, one part of the electrophorus will be
complete. Next provide a round plate of
wood, about ^ an inch thick, and 6 or 7
inches over, which must have a smooth edge,
and without any sharp points or angles;
cover this with tin foil, and fix a glass rod
to the middle of it as a handle. This may,
altogether, cost 2s, and is a really useful
electrical machine, capable of showing all the
fundamental facts of the science. The fol-
lowing cut will render the description more
evident : —

placed upon a glass stand, and two pith balls
be suspended from the rim of it ; whenever
the upper plate is lifted up these balls also
will diverge, showing that the lower plate
also appears excited when separation of con-
tact ensues. Many other experiments with
this instrument will afterwards be shown

121. To excite it, warm and wipe the
glass handle, and also the resinous plate.
Rub this plate briskly with a warm flannel,
and put the wooden plate upon it, holding it
by the glass handle — touch the wooden plate
for a moment with the finger, and it will be
full of the fluid in a disturbed state, not,
however, apparent until the wooden plate is
lifted up, when a spark may be taken from
it ; put it down again, touch it with the finger,
and lift the plate up again, (first removing
the finger,) and a second spark may be
taken, and so on for a considerable length of
time.

122. Fasten near to the edge of the upper
plate of the electrophorus a bent wire,
bearing on the end of it two suspended pith
balls — whenever the upper plate is removed
from the lower, both being excited and
touched with the finger, as above directed,
the pith balls will be violently repelled from
each other.

123. If the resinous plate be excited, and

Numerous experiments of the last chapter
evidence the same fact, which is rendered still
more conclusive by the following machine,
called

THE CIRCULAR RUBBING MACHINE.

This consists of a square frameof wood BB,
supported by a square footA, having a circular
rubber or cushion D, stuffed with flannel and
covered with leather, which is turned by a
handle at top E. This rubber rests upon a
plate of glass C, about 8 inches in diameter.
The under surface of the glass has pasted
upon it a round piece of tin foil. 3 oi 4 inches
over, with two pith balls hanging by fine
wires, or a thread, from the centre of it.

Ex. 124. Prepare the apparatus by
warming the glass, and spreading a little
amalgam on the cushion — turn round the
handle, which will produce a friction, and
excite the glass. In this state there will be
no appearance of the fluid being disturbed,
until the cushion be lifted up, when ths balls

27

will diverge — placing it down again their
motion will cease, and thus they may be al-
ternately moved by producing and separating
contact.

Electrical amalgam. — Melt in a ladle \ an
ounce of zinc. When melted, add and stir
up with it 2 ounces of quicksilver. When
I old pound it with a little wax or grease,

when it will be fit for use. This substance is
of value to the electrician, as being the best
of all matters to excite glass with, so that in
the electrical machine such is indispensable,
and if we had used it, spread upon a piece of
leather, in Ejc. 6, 9, and others, instead of
the old black silk handkerchief, the effect
would have been much greater.

CHAP. lY.

OF THE ELECTRICAL MACHINE AND MANNER OF USING IT.

In our future experimental researches on electricity it will be necessary to use a machine,
for the purpose of accumulating the fluid in greater quantity than the glass tube or such
simple means allows, and also of retaining it in such a condensed state as to afford the
powerful effects of which it is capable. From the last chapter it became evident that to
excite, accumulate, retain, and transfer the electric fluid, a due knowledge of electrics and
conductors was necessary; — that the capability of excitation and retention depended upon the
quality of the electric, and the power of a rapid transmission of the fluid ; upon the perfect
conducting power of the material through or over which it was to pass. Electricians employ
for the one purpose chiefly the metals, they being the best conductors ; and sulphur, glass,
resin, and silk as electrics, or as bodies to be excited. The proper union of these forms
an electrical machine.

In the early history of the science, when
attraction and repulsion only were to be ob-
served, all that the electricians aimed at was
to give the requisite friction to the electric in
a more convenient manner than by the simple
experiments of rubbing upon the sleeve, or
with other light material. With this in lention
Otto Guericke fitted a globe of glass; upon

an axis. Upon giving it a whirling motion,
and holding his hand against it at the same
time, he was enabled to excite it with great
convenience. Mr. Hawkesbee's machine, and
which was so similar to this, that one illus-
tration will serve for both, was the next con-
trivance. It is shown in the cut.

It will be seen that here is no cushion, no
conductor, no means of collecting the fluid
from the earth, and none to draw or collect
it from the cylindtr, as we shall presently
show are all necessary. Therefore, although
answering the purposes then required, it is
very inefficient compared to our more modem
inventions. Otto Guericke had no means of
forming a globe of sulphur but casting it in a
glass globe, and then breaking the glass from
off it. Mr. Hawkesbee used the glass globe
itself rather than that of sulphur, and in that
was the great difftrence between his machine
and that of Otto Guericke.

The next machine was invented by the Abbe
Nollet. Of this description was the greater
part of the machinps which were used about
one hundred years since. It is represented
annexed : —

28

(^*

These were the machines, heavy aid ;Tn-
wieldy as they seem, which were carried about
from place to place for exhibition. The ad-
vantage of this machine over the last was its
different and more convenient form, and the
appendage of a conductor, which was hung by
silk lines from the ceiling. The globe was
still rubbed by the hand. The conductor was
a bar of iron, or generally a gun barrel, con-
nected to the electric by a chain hanging noin
it, and touching the revolving globe.

In the next machine constructed, four
globes were whirled at once ; it was a con-
trivance of Dr. Watson, and is represented
beneath : —

The conductor was, as before, suspended
from the ceiling, and connected by the various
globes by unravelled gold lace hanging down
from them. As it was evident that the hand
could not be held against four globes at once,
a cushion was appended to each globe, and
hence arose another great improvement — in-
deed the machine was now furnished with all
its most valuable parts; a globe to be excited.

a cushion to supply the fluid, and a prime
conductor to collect it. Still, as will be evi-
dent, it was very large and unwieldy, and
the necessity of suspending the conductor
from the ceiling a great inconvenience. The
improvement therefore of Mr. Wilson was
particularly acceptable to the electrician.
This gentleman's machine is as follows : —

A cylinder is substituted instead of a globe ;
the cushion is placed beneath. This was a
great improvement. The conductor was
suspended on silk lines fastened to upright
pillars of glass. Instead also of the uncertain
method of a chain or fine wire hanging down
from the conductor to the cylinder, Mr.
Wilson substituted a second rod, which was
terminated at the end by a row of points ;
another great improvement. The greatest
inconvenience of this machine was the great
strength required to be given to all its parts
to prevent the conductor from vibrating to
and fro, when the cylinder was put in motion
by turning the handle.

The next machine was much more portable;
it was invented by Mr. Nairne. The differ-
ences between this and the former were that
the globe was turned by means of some brass
wheel-work contained in a box beneath the
globe, and which for the first time was made
to work by a vertical motion ; — the cushion
was made with a spring, to produce equality
of pressure, and the conductor was in a
greater degree unconnected with the globe
than before. It is represented beneath : —

29

A second machine, also we believe by Mr.
Nairne, has a cylinder, working vertically,
with a multiplying wheel beneath, and another
on the table. The conductor is made of tin,
and instead of a series of points attached to
it, it has the edges of the end of the prime
conductor cut like teeth. This was invented
about 1760, and consequently after the dis-
covery of the Leyden jar. It was used also
entirely for medical electricity, which ac-
counts for the Leyden jar B, and also for the
electrometer at the side being attached to it.
These, however, are in reality no parts of
the machine itself. Mr. Nairne first used
amalgam to the electrical machine. This
machine is represented in the following
tut : —

Thus in the hands of Mr. Nairne, who was
a celebrated optician in Cornhill, that which
was before cumbrous and comparatively in-
eifective, became a useful, portable, and
easily- constructed instrument, rendered how-
ever yet more convenient and powerful by the
horizontal position of the cylinder, and the
silk flap introduced by Dr. Priestley. This
was the history of what is now called the
cylinder machine, which is shown in its
modern and most approved form, as follows.
Be it observed, that the cylinder machine
varies in having sometimes two conductors ;
one attached to the cushion for negative
electricity, and the other for positive elec-
tricity ; this last is always present, and is
called the pi'ime conductor. It may also be
turned by a common handle, or by a multi-
plying wheel, as found most convenient ;
we decidedly prefer the former, particularly
for a large machine.

THE CYLINDER MACHINE.

' A is a g.lass cylinder, having upon each
end of it a cap of wood or brass, and sup-
ported by a stand with two uprights. The
end of one cap is turned with a pivot, which
fits into a hole near the top of one of the
uprights. The other cap is turned with a
similar pivot, and has beyond this a flanch
and a square gudgeon, upon which a handle
D fits. This end of the cylinder is supported
in a similar manner to the other end, but
instead of a hole merely being bored in the
upright leg, a portion is cut away, that the
cylinder may be the more easily taken out
and put up again in its place ; it may be se-
cured when there by a pin run through the
upright, just above the axis of the cap.
Before the cylinder is a cushion, which ex-
tends in length to within an inch of either
end of the cylinder ; it is from 1 to 2 inches
in width, according to the size of the cylin-
der, and made by laying five or six folds of
flannel over the wooden back of the cushion,
and neatly covering these with leather.
The cushion when finished should be soft,
and yielding about as much as a wool mat-
tress, and scarcely so hard as the bottom of
a hair-covered chair.

On the lower part of the cushion is glued
a flap of leather (the rough side outwards),
and on the edge of the leather the silk flap
which passes over the cylinder when in action.
B, the cushion, is supported sometimes by a
thick rod of glass with a wooden spring at
the top of it, as in the figure ; at other times
a springy piece of wood alone is used. It is
fastened at the top to the cushion by a hand-
screw, which passes through the support, and
is fixed by a thread in the back of the cushion
itself. The lower end of the support for the
cushion is made so as to slide backwards and
forwards, either on the top, or still better
underneath the stand, and is held in its
position by a thumb-screw. The object of
this sliding is to regulate the pressure of the
cushion against the cylinder, as shown in the
cut, or the cushion may be made a fix-

30

ture, and its pressure regulated by a screw
behind it, as at the letter E, in the cut of
the whole machine above given. When the
cushion slides backwards and forwards, a slot
or long hole is made in the foot board, and
the small piece of wood which forms the foot
of the cushion slides in a groove beneath the
foot board. In the cut A shows the back
of the cushion. B the leather flap. C the
silk. D the wooden spring. E the glass
support. F the cap, which unites the glass
and spring. G the foot. H the holding screw.
The part D is united to A by a round wooden
screw on which a chain is hung when the
machine is in use ; this chain ought to touch
the ground.

C represents the prime conductor, formed
either of wood covered neatly with tin foil,
or of metal. It has round and smooth ends,
at one of them a ball and wire for the sus-
pending of various apparatus, at the other a
projecting wire furnished with a row of points
to collect the fluid when, disturbed by the
cylinder. It is necessarily supported upon a
glass pillar, sometimes attached at the lower
end to the same stand as the rest of the
machine, in which case the conductor runs
parallel to the cylinder, and has the points
driven into the side instead of the end. At
other times it is fixed to a separate foot as is
to be seen in the figure beneath. At the top
of the conductor are two or three holes to
aflpDrd greater facility in performing experi-
ments.

To make a machine. — In makin;; a cylin-
der machine observe carefully the following
directions : — The centre of the cylinder, of
the cushion, and of the conductor should be
of the same height. The lower part of the
cylinder, unless in a very small machine,
should be at least 10 inches above the foot
of the stand beneath. The glass pillar of the
prime conductor not less than 14 inches long,
the conductor itself about as long as the cy-
linder, and from 2 to 3 inches diameter ; the
points projecting nearly an inch. The silk
flap should be thin, and extend to within an
inch of the points. Fix the caps upon the
cylinder thus : — Make some cement, (ac-
cording to the receipt in p. 8,) which have
melted ready for use ; roughen with a file
the glass on each end of the cylinder, and

bore a small hole through the axis of that
cap which does not bear the handle ; this
done, stop up the inner end of the hole again
; with a small piece of dough, putty, or clay.
-Now grease the outside of this cap well, put
[it in an upright position, half fill it with the
1 melted cement, warm well the end of the
'cylinder, put it upright into the prepared
cap, let it remain till the cement is hard, and
then clear out the hole through the centre
by a hot wire ; being very careful that it is
at all times afterwards left open. This is
necessary as a vent for the heated air, which
of course will be liable otherwise to burst
the cylinder, not merely when the other cap
is fixed to it, but ever afterwards when the
machine is in action. The hole being thus
opened, the other cap may be fixed on in
the same manner ; a second hole however is
not necessary. The cause of greasing the
outside of the cap is that any cement which
flows over may not stick to it.

By attending to the above description and
observations, an electrical machine may be
made out of a common sample phial, capa-
ble of giving sparks, charging a Leyden jar,
and performing most of the simple electrical
experiments.

To work the machine. — Warm the whole
well before the fire, and cleanse it from all
damp and dust. Take off the cushion, scrape
away all dirt, spread evenly upon it some
freslx amalgam, (a receipt for which see page
27 ;) put it back in its proper place, and
fasten to the screw which connects it with its
upright a brass chain, the other end of which
reaches to the table or floor, or the walls of
the apartment. Upon now turning the han-
dle, streams of fluid will be seen to issue
from the cushion, and passing under the silk
to fly off at its edges. To collect the fluid,
place the conductor with its points about a
quarter of an inch from the edge of the silk,
which will so readily attract the fluid from
the cylinder that sparks proportionate to the
extent of the glass surface rubbed may be
taken from it, being very careful however
that the glass stand of the conductor be per-
fectly dry. The pressure of the cushion
against the cylinder is to be regulated by the
screw on the stand at bottom.

Note. — If the machine be small it will re-
quire frequent warming ; the power of a
machine is generally increased by rubbing
the cylinder for a minute or two with a
slightly.greasod rag, or by putting one hand
upon the cushion.

The rationale of the action going on is
this : — The fluid passes from the earth through
means of the floor, walls, &c., to the chain
suspended from the cushion ; here friction,
which is the cause of the disturbance, takes
place. The disturbed fluid passes to the

31

glass cylinder, and is confined from escape
by the silk flap ; that ceasing, the fluid
would fly to anything around, particularly to
a pointed body, or a lighted candle ; but this
is prevented by the superior attraction for it
from the nearer end of the prime conductor
put to receive it. Thus it will be at once
seen that an electrical machine resembles a
pump ; the earth may be likened to a well
of water ; the chain to the lower pipe of a
p'ump ; the cushion is the sucker ; the silk
the nozzle ; and the prime conductor is like
a pail to hold the fluid.

palmer's cylinder machine.
Mr. Palmer, an optician of Newgate
Street, has so far modified the cylinder ma-
chine as to adapt two cushions and two
prime conductors to it, as will be readily
understood by the following figure and short
description : — A is a thick glass tube, having
a ball at the top, and two arms, projecting
sideways, furnished with points as C C. The
tube A. supports one end of the cylinder,
and is itself supported upon a solid glass
pillar D. B B are glass pillars, which sup-
port the cushions and flaps.

CUTHBERTSON S PLATE MACHINE.

This machine is undoubtedly superior to
the cylinder machine, both in power and de-
gree of portability ; but it cannot be so
readily made by an amateur, and it is attended
by a great defect, namely, that the plate of
glass which forms the electric to be rubbed
is very apt to become starred or cracked
from the centre outwards. This takes place
from two causes ; one, unequal pressure of
the cushion, and still more frequently from
the following want of care. Previous to an
electrical machine being worked it is usual to
place it near the fire to become dry, and in
a slight degree warm. Now it is evident
from the shape of the plate machine, that the
side of the plate would be placed, nine times
out of ten, towards the fire, and of course

the opposite side exposed towards the door
of the room or window. The side nearest
the fire becoming warm is expanded, while
the other side, glass (being a bad conductor of
heat,) will remain as at first ; the glass plate
is therefore distorted, and if the door be
opened by a person entering, a sudden con-
traction takes place in the nearer side, which,
added to the expansion of the other, cracks
the glass at its point of support, or fulcrum,
which is the centre. Again, if when the glass
plate is unequally heated, the cushions be put
on tightly, and the handle be then turned,
fracture is almost certain. With these draw-
backs upon its utility the plate machine is
still better than the cylinder, especially for
lecturing before a large audience, as it is less
liable to be aff'ected by the moisture of the
apartment, arising from breath and other
causes. It is figured and described as
follows : —

A is the plate of glass, which is made cir-
cular, and has a hole drilled through the
centre for the admission of a spindle, so that
it may be turned by the handle B. C C C C
are four cushions, fixed tv,o and two together
to rub against the glass. D D are two double
flaps of black silk. E is the prime conductor,
which is of metal, terminated by a ball H at
one end, and after branching into two arms
F F, which are bent at the part next the plate,
terminating with points as at G G. I and J
are glass rods to support the prime conductor.
These are not both necessary if the machine
be small ; the rod marked I will then be
sufficient. The structure of the cushions
and the prime conductor is seen in the an-
nexed cuts.

A represents two cushions, or rather two
vertical pieces of wood, on the inner side of
which two cushions are to be placed. The
cushions merely fitting in a groove or hole,
or else attached on a projecting pin or two,
that they may be taken off and put on again
readily on putting the machine in order.
The cushion and also these pieces may be

32

•bout an inch wide, and of such a length as
to leave 4 or 5 inches between their inner
extremities and the brass flanch of the cen-
tral axis of the plate. The pieces A, or
cushions, may also take oft" by unscrewing
the hand screw at the top, marked C, which
passes through the top frame of the machine
D. E is a screw to regulate the pressure of
the cushion upon the plate. B represents
the silk flaps ; thc-e being one to each side
of A. These are sewed together around the
outer edge, so that the plate revolves between
them. Any common silk of a black color
will answer for tViis purpose, and it is quite
immaterial if it be previously oiled or not.

The annexed figure shows the prime con-
iductor, as separated from the machine, or

rather a vertical representation of the whole
machine, except the stand and cushions.
A A is the plate of glass. B the handle.
C C the supports. D D D the prime con-
ductor, all of brass. E its horizontal glass
support. F F bent metallic arms, with
points to collect the fluid from the glass.

Other machines have been invented, o
more or less utility, but all these merge intc
the foregoing, and are therefore easily
understood.

CHAP. y.

ELECTRICAL ATTRACTION, REPULSION, INDUCTION, AND
DISTRIBUTION.

We have already said so mv-ch about electrical attraction and repulsion, that we have no^
but little to add, m.ore than to illustrate the subject by those more showy experiments whicl
the greater power we have obtained by means of the electrical machine enable us to exhibit
and to explain the laws which seem to regulate the degree and continuance of those efTectt
Bearing then in mind the theory of Franklin, that a body may be charged positively o
negatively, and that the electric fluid is repellant of itself, but attractive of all othe
matter, we shall be able to establish these laws.

1. Bodies that are electrified positively repel each other.

2. Bodies that are electrified negatively repel each other.

3. Bodies electrified by contrary powers attract each other.

4. Those substances that are brought within the influence of electrified bodies become
possessed of a contrary electricity, or electrified substances, without parting with their owi
electricity act upon other bodies in their own neighbourhood ; producing in them at
electricity which is contrary to their own, or bodies which are immerged in an electric
atmosphere, always become possessed of an electricity contrary to that of the body in
whose atmosphere they are imrnerged.

33

5. That the degree of attraction or repulsion is inversely proportionate to the square
of the distance of the electric body and that it acts upon ; that is, if an uaelectrified body
be offered to another which is electrified, consecutively at the three several distances of
1 inch, 2 inches, and 4 inches, as the squares of these numbers are 1, 4, and 16, we have
only to invert these, and we shall find that if at 1 inch distance, the attractive force be 16,
at 2 inches it would be as 4, and at 4 inches as 1 only ; or, in other words, if the attractive
force at 1 inch be as 1, at 2 inches it would be as ^, at 3 inches ^, and at 4 inches as ^,
and so on for higher numbers.

This fifth law, although important in proving the niceties of the science, and in showing
that the laws of other sciences or powers of nature are accordant to those of electricity, yet
as its full exposition will yield no experiments of a popular character, we will pass it over
with the mere description of the method by which it is proved. It was ascertained by
Mr. Canton, that an electrified body communicates its own electricity to all the particles
of air which come in contact with it. These particles are immediately repelled, and their
place supplied by a new set of aerial particles. The consequence of this must be, that
the air immediately surrounding an electrified body must be also electrified, and must
possess the same kind of electricity with it. It is obvious that the electrical density
of this air must diminish according to its distance from the surface of the excited body ;
hence, according to Lord Stanhope, the reason why bodies charged with the same kind of
electricity repel each other is, that they may move to those parts of their atmosphere where
the electricity is least. Bodies excited with different kinds of electricity, on the contrary,
approach each other, because each moves towards the extremity of its electrical atmosphere.
Without introducing the mathematical formulse of his lordship, as published by him in
1779, we shall introduce the more easily-understood remarks of Coulomb, published seven
years later. For the purpose of these experiments, Coulomb used his electrical balance,
already described. Having electrified the two balls of the balance by means of the head
of a large pin, the index of the micrometer standing at 0, the ball of the needle
separated 36°. Secondly, having twisted the suspending wire 126°, the balls approached
each other, and remained at 18° distance. The suspending wire being twisted 567°, the
two balls approached within 8^° of each other. In the first case, the index of the
micrometer being at 0, the balls separated 36°. In the second case, the distance of the
balls was 18°, but as the micrometer was turned 126°, it follows that at the distance of 18°
the repulsive force was 144°. Thus, when the distance is reduced to one-half the repulsive
force is quadrupled. In the third case, the suspending wire was twisted 567°, and the
two balls were reduced to the distance of 8^° from each other. Here the actual tortion
was 576 or four times as much as in the second case, and there is only half a degree wanting
to render the distance of the balls, in the third case, one half of what it was in the second.
The distance being 8|° in the third case, 18° in the second, and 36° in the first. The half
degree lost in the third experiment is to be accounted for by the loss or dispersion of the
fluid during the experiments, which lasted four minutes. Thus it follows, that the repulsive
forces exercised upon each other, by two balls charged with the same kind of electricity,
are inversely as the square of the distances at which they are from each other.

We will illustrate the other laws by more popular experiments, some of which may
performed by the excited glass tube, and the rest by holding towards or annexing to the
prime conductor of the electrical machine the apparatus described.

34

Ex. 125. Suspend from the ceiling a string,
and from this a feather, attached to a thread
of silk, or the ball of the pendulum electro-
scope will do as well. Hold towards it an
excited glass tube, the feather will first adhere
to it, then be repelled, and if a finger be held
near it, be attracted towards the finger. The
attraction of the feather and tube is accounted
for — they are differently electrified. The
receding of the feather is also accounted for,
for after touching each other they are simi-
larly electrified ; but why the feather should
seek the finger is not so apparent. It arises
from a cause, which, instead of militating
against the truth of Franklin's laws, does but
prove the general applicability of the above.
It was stated that when a body of any kind
is electrified, it affects and repels the electric
fluid contained in all the bodies near it, and
thus the overcharged feather drives away
some portion of the fluid in the finger, in
consequence of which the part of the finger
nearest to it becomes negative, or in a dif-
ferent state from itself — therefore they are
mutually attracted.

126. Diverging threads. — Tie twenty fine
linen threads together at each end, so that
there may be about 8 inches distance from
knot to knot ; hang this by a wire loop, fas-
tened to one of the knots, to the conductor
of the machine. Upon charging the con-
ductor, the threads will recede from each
other, forming a curious balloon-shaped
body.

^^=iO

127. Expanding threads. — Instead of
tying the threads at both ends, let the lower
end be loose, and upon turning the machine
they will form a brush.

128. The glass feather. — Procure a glass
feather, as made at the fancy glass shops,
and stick it into one of the holes on the up-
per side of the conductor ; when the machine
is put in motion the radiation of all the fila-
ments of glass will offer a most elegant
object.

129. The frightened head of hair.— As a
variation of the last experiment, the head of
a doll is furnished with a wig of hair, which

is 2 or 3 inches long ; upon electrifying this,
" each particular hair will stand on end" in
the most grotesque manner, and thus it is
with every person who is electrified, when
on a glass-legged stool. This experiment
becomes most effective, because seen more
conspicuously, when the hair is of a grey
color.

130. Radiating feathers. — Let a metal
ring be supported upon a glass pillar, and at
six or eight equally-distant points around
this ring tie a thread (not silk) a (ew inches
long, the other end of which bears a feather.
Connect the metal ring with the conductor
of the machine by a wire or chain, and the
feathers being electrified will repel each other
until they will stand at equal distances like
the spokes of a wheel.

131. The electrified cloud.— Take a hand-
ful of wadding or raw cotton, squeeze it to-
gether tight, yet so that the threads shall not
be entangled. Place it upon a flat, smooth
board, connected with the prime conductor
of a machine. Upon electrifying the board,
the cotton will separate itself, and expand
until it becomes a large fleecy mass, and if
the machine be in good action, the whole
mass of cotton will fly away. Indeed it may

33

always be made to fly off, if the quantity be
proportioned to the strength of the machine.
Let it be remarked, however, that it will soon
fall to the ground, not only because of the
attraction it has for other bodies, but because
of the gravitation it naturally has, and which
is not altered in any degree by the electriza-
tion, unless an excited tube be constantly
held towards it, when one power will, if
strong enough, counteract the other.

132. Electric fish. — Cut a piece of very
thin leaf brass (such as is called tinsel will
do) with an obtuse angle at one end, and an
acute one at the other ; present the large end
towards an electrified conductor, and, when
the brass is within its atmosphere, let it go ;
it will then fix itself to the conductor by the
apex of its obtuse angle, and, from its con-
tinual wavering motion, will appear to be
animated.

133. Suspended leaf. — Hold towards the
ball at the end of the conductor a square
thin leaf of brass or paper ; upon turning the
machine, it will leave the hand and be sus-
pended with one of its points upwards be-
tween the hand and the conductor.

134. The moving leaf.-~Mo\e the hand
round, and at a uniform distance from the
ball of the conductor, when the leaf of brass
is suspended near it, and it will be seen to
move with the hand in any direction which
the latter may take.

135. Animated thread. — Present a fine
thread to an electrified conductor ; when it is
at a proper distance it will fly towards, and
stick to the conductor, and convey the elec-
tric fluid from it to the hand ; remove the
thread to a small distance from the con-
ductor, and it will fly backwards and for-
wards with great velocity, and in a very
pleasing manner. Present the same thread
towards one that hangs from the conductor,
they will attract and join each other. Bring
the finger, or a brass ball, near these threads,
the ball will repel that held by the hand,
and attract that which is affixed to the
conductor.

136. Dancing images. — To the end of the
conductor, suspend a plate, made either of
metal or wood, covered with tin foil, and at
a distance of 3 or 4 inches under this a
similar plate, but one that is rather larger.

Place on the lower plate any little figures
cut out of paper or pith. Take care that the
lower plate is supported upon some con-
ducting substance ; turn the machine, and
the figures will raise themselves, and fly up
and down between the two plates, formir\g a
most ludicrous dance.

137. Support the lower plate upon a glass
bottle, or other insulator, and although all
the rest of the apparatus remain as before,
yet the figures will not dance. The reason is
this, the upper plate being charged by its
connexion with the machine, the figures are
attracted by it, they becoming charged are
repelled by the upper, and attracted by the
lower plate. When they touch this their
charge is removed by that contact, and con-
veyed to the earth, while the figures jump
up again for a fresh supply, and thus they
move alternately from the one to the other
plate. When the lower plate, however, is
insulated, the extra portion brought to it
cannot escape, and it becomes charged in the
same manner as the upper one, therefore
the figures have no tendency te move between
them.

Note. — If in cutting out the figure the head
is heavier than the feet, it will dance head
downwards ; damping the feet in the mouth
will usually remedy the defect, but this, at
the same time, gives them a tendency to ad-
here to the upper plate, while wetting the
head makes them dance on the lower plate.
Female figures usually dance more regularly
because of the weight of the lower part of the
dress. In all the figures the head should be
somewhat pointed, either by the adjunct of
a steeple-crowned hat, or something similar
put upon it.

138. Dancing pith balls. — Place upon the
lower stand, (mentioned in Ex. 136,) six or
eight balls of the pith of elder, and cover

36

them over with a dry tumhler, Hang to the
conductor a chaiw, which touches this tum-
bler; upon turning the machine, although
glass intervenes between the exciting power
and the balls acted upon, yet the balls will
fly rapidly up and down within the glass
tumbler. In this instance, the outer part of
the glass is by contact electrified positively ;
the inner part, therefore, will be by induction,
(afterwards to be explained,) electrified ne-
gatively ; and the balls are flying up and
down to supply the deficiency of the glass —
each ball coming to deposit its load, and flying
down again for another.

139. The dancing pith ball experiment
may be reversed thus : — Fasten to the con-
ductor a pointed wire as before. Hold a dry
and warm tumbler over the point, and turn
the machine. After a few turns the tumbler
will be charged withinside with positive elec-
tricity. Place upon a table, or a metal plate,
a few pith balls, and cover them over with
the charged tumbler. They will now jump
up and down, each one conveying some of
the fluid away from the glass, and not towards
it, as in the latter instance. They continue
to dance long after the machine ceases to act,
and when their motion has ceased altogether,
it may be renewed by merely putting the
hand upon the outside of the glass.

140. To make pith and cork halls. — Pro-
cure some of the thick young shoots of the
common elder-tree, cut them into lengths
between the joints, and push out the pith of
each length by a smooth stick, as near as
possible the size of the hole where the pith
is, and dry it for use. When wanted for balls,
cut out each ball moderately true with a pen-
knife, and to round them more perfectly,
and take off the rough edges, roll them very
gently, with a circular motion, on a smooth
tabic, and they will be fit for use Cork balls

may be cut in the same manner, but to make
them smooth each one must be placed upon
the point of a needle, and turned round two
or three times in the flame of a candle, or
should the blackness thereby occasioned be
an objection they may be rubbed with sand
paper.

141. Electric hells. — The apparatus thus
called is of various forms, that put into action
by attraction is represented beneath : — It
consists of a rod or wire, having a hook to
hang it up by, and a small chain at each end,
terminated by a bell. There are, also, at
three other parts depending from it three
silk threads, one terminated by a third bell,
the other two by metal clappers. The third
bell, it win be observed, has a chain appended
to it which reaches the ground. When this
apparatus is suspended from the conductor,
the wire at top, and the bells at the sides,
become electrified — these latter, therefore,
attract the clappers. They thus becoming
charged, recede till they touch the centre bell,
and thus the motion of the clappers, from
one to the other, produces the sound of
ringing.

142, Electric swing. — Balance a small
figure upon two fine silk strings, and place
it within 3 or 4 inches of a ball which forms
part of a conductor, while on the other side
of the figure is a second ball connected with
the ground. Upon putting the machine in

37

action, the figure will vibrate from one to the
other.

The above figure represents such an in-
strument. A is a ball attached to the prime
conductor of a machine. C is a ball con-
nected with the ground. B is a stand above
which is a figure suspended by silk, and sup-
ported by two glass pillars ; though these last
are not absolutely necessary, because the silk
will be sufficient to prevent any charge the
figure may receive from being dissipated
before it arrives at C, the proper place to
deposit it. The ball A may be dispensed
with, if the pillars be glass, and the figure
suspended on linen, the top of one of the
pillars bemg connected with the conductor.

143. The electric seesaw. — Suspend a strip,
or fine rod of glass upon a centre, and upon
each end of it support a light figure of pith.
Let ovie of the figures have no conducting
substance under it, nor yet touch the con-
ductor when swinging upwards ; but let the
other figure come against the ball of the
conductor when it rises highest, and touch
another ball connected with the ground when
descending lowest ; if put properly under the
conductor of a machine it will vibratp up and
down — the opposite figure only acting as a
counterpoise to it.

This apparatus is annexed : A is the con-
ductor. B the conducting figure. C the
counterpoise ; and D the part connected with
the ground, to carry away the fluid brought
down by B.

144. Electrical spider. — Cut out of a bit
of cork the body of a spider ; furnish it with
eight white thread legs, and run through the
body a long black silk thread. Hold this up
in one hand, so that it shall hang 2 or 3
inches from the side of the conductor, and
hold the finger about the same distance be-
yond it — when the assistant turns the machine
the spider will fly backwards and forwards
between the conductor and the finger.

145, The electrical rope dancer. — Sus-
pend from the ball of the conductor two thick
wires, about a foot long. The upper wire is

connected with the conductor by a small chain
or hook ; the lower one is hung to this, at
the distance of 2 or 3 mches, by a silk thread
at each end ; the lower wire is also connected
with the ground by a chain. Place on the
lower wire a paper or pith figure, and upon
putting the machine in action, it will move
alternately and briskly between them, x

This experiment is but a modification of
the dancing figures, described xnEx. 136. In
the cut above given, the two wires appear
unconnected with each other, the lower one
having a stand of its own. This is a better
form of the apparatus, because when con-
nected together by silk, the figure put to dance
is apt to cling to the silk, which destroys the
eff'ect intended to be produced.

146. Spinning sealing wax. — Fasten on
to a thick wire a piece of sealing wax, about
one inch long, by heating it, and thrusting
the wire into it. Put the other end of the
wire into a hole, either at the end or side of
the conductor, so that the wax shall be at
some distance off. Underneath where the
wax is, either on the table or the floor, place
a sheet of brown paper, merely to catch any
drops which may fall when the wax is in-
flamed. Provide yourself also with a lighted
candle, and a sheet of white paper, Direct
your assistant, (for in this experiment you
must have one,) to turn the machine, and
stop it exactly at the time you may desire.
Then standing near the wax, hold the white
paper 4 or 5 inches from it, and light the
sealing wax. When well lighted, blow it out,
and at the same instant let the machine be
turned, and exceedingly fine threads of wax
will be thrown ofi", and collected on the white
paper, as long as the wax remains melted.
Stop the machine, light, blow out the wax,
and turn the machine as before — more of
the filaments will be thrown off, and thus
any quantity may be collected, and if scraped
together by the point of a pin, it will re-
semble the finest wool, such as cannot be
procured by any other means.

147. Electrified camphor. — Connect a
spoou or small metal cup, with the conductor

SB

of a machine, light the camphor, and then elec-
trify the conductor ; the melted camphor will
throw out the most beautiful ramiiications as
long as the machine is turned. This experi-
ment is even more beautiful than that with
sealing wax.

148. The electrical pail. — Suspend to the
ball, which projects from the prime conduc-
tor, a small metal or wooden pail, having at
the bottom of it a hole, so fine that water
will pass only by drops. Pour a little water
into it, and when electrified, the water instead
of dropping only will pass out in a stream,
and this will divide itself into several streams,
each of which in the dark will be beautifully
luminous.

149. Insulate a small condensed air foun-
tain and electrify it ; the jet will be minutely
subdivided and expanded over a considerable
space, but will return to its original limit
when the electrization is discontinued.

150. Suspend one pail from a positive
conductor, and another from a negative con-
ductor, so that the ends of the jets may be
about 3 or 4 inches from each other. The
stream proceeding from one will be attracted
by that which issues from the other, and
form one stream which will be luminous in
the dark.

151. Hang two pails about 4 inches apart
on the same conductor, and the streams
which issue from them will recede from each
other.

152. Place a metal basin on an insulating
stand, and connect it with the prime con-
ductor ; then pour a small stream of water
into the basin, which in the dark will have a
beautiful appearance, as the stream will be
divided into a great number of lucid drops.

153. Hold a pail which is furnished with
several capillary tubes, placed in various
directions, near an electrified conductor, and
the water will stream out of those jets near
the conductor, while it will only drop at in-
tervals from those which are opposite to it.
A most remarkable exemplification of the
laws of induction is seen when the vessel con-
taining the water is made of a long form,

and placed at right angles to the prime con-
ductor of a machine, minute holes being
pierced on the underside of the tube at 3 or
4 inches distant from each other. The tube
should be suspended by silk. Upon turning
the machine, the water from the ends will
fall in streams attractive of each other, while
from the middle hole it only drops. In the
dark with a powerful machine, and 4 or 5 feet
distance for the water to drop, this is a most
splendid experiment.

154. Conical drop. — Place a large drop of
water upon the end of a smooth metal rod ;
hold it to the prime conductor when excited,
and the water will first assume a conical
form, and then fly to the conductor.

155. Let a drop of water hang from the
ball at the end of the prime conductor, and
hold towards it a wine glass or spoonful of
water. The one will attract the other, so
that the drop will lengthen itself according
to the force of the electricity.

156. Fiery sponge. — Suspend in like man-
ner to the bucket a sponge dipped in water,
and the luminous streams which issue from
it will be more numerous and beautiful than
even in the last example.

157. Electric planet. — Suspend from the
conductor of a machine a brass ring, about a
foot in diameter, and underneath it, at about
i an inch distance, a metallic plate connected
with the ground. Place upon this plate, and
within the ring, a very light hollow glass ball
— turn the machine, and the little ball will
describe an orbit around the ring, and turn
at the same time about its own axis. 'The
poles of it? rotation are nearly at right angles
to the plane of its orbit. We have not tried
this experiment. Mr. Adams says, " that
it requires considerable attention to make it
succeed, as a small difference in the apparatus,
or in the force of the machine, &c., will
occasion a failure."

158. Electric swan. — Procure a waxen
swan, and which may be bought for a few
pence at the pastry-cook's, who use them to
decorate twelfth-cakes ; cover the throat and
breast very neatly with tin foil, which may
be painted over afterwards to prevent its
being seen ; or the whole may be covered
with gold leaf. Let the swan float in a
basin of water, which is supported upon a
glass stand, suffer a chain to fall from the
prime conductor to dip into the water ; turn
the machine and hold a piece of bread to the
swan, it will immediately turn to it, and
approach as if to eat the bread. The swan
may be made of cork, and if an electrical
stand is not at hand, a very excellent one
may be made with a wine bottle, a flat and
smooth piece of wood being nailed to a peg
which fits into the top of the bottle. A sheet

39

of paste-board or a cover of a large book
made warm answers the same purpose.

^^

159. Electric boat. — Make a small boat
ot wood, with a cork figure apparently row-
ing it ; upon presenting a finger, the boat
will approach, and may thus be carried round
the basin in which it is floating.

HENLEY S aUADRANT ELECTROMETER.

The repulsion which takes ])lace between
bodies which are elec-
trified, suggested this
valuable instrument, the
object of which is to
ascertain the degree of in-
tensity to which any elec-
trified body is charged,
particularly the Leyden
jar. It consists of a
shank of wood, with a
brass ferule and point
at the foot, which latter
fits into one of the holes
of the prime conductor,
Bnd is terminated above
by a wooden ball turned
out of the same piece of wood, mostly ma-
hogany. To the side of the shank and near
the top, is glued or otherwise fastened a
semicircle of ivory, graduated on the edge
to angular measurement, so that the whole
semicircle is divided into 180°, and of course
the point of it most distant, or at right an-
gles to the stem, is 90°. In the centre of the
circle, of which the semicircle is the half, is
supported on a pivot a very thin wooden
pointer, so that it may move up and down in
a vertical line. A pith ball is placed at the
outer end. If this apparatus be inserted in a
hole of the prime conductor, or any other ob-
ject strongly electrified, the pith ball and its
stem will rise by electrical repulsion, and
indicate by the degree they cut, the strength
of the electrization. The greatest energy or
abundance of fluid will make it subtend the

angle of 90°, a less degree of force GO, 50,
40, &c. degrees. This, although a useful
instrument, is by no means an accurate in-
dicator of intensity, because of the effect
which gravitation has upon it. All the elec-
trometers and electroscopes, previously de-
scribed, act by the same principle.

INDUCTION.

The circumstances of electrical repulsion
taking place between bodies similarly electri-
fied is a natural consequence of the fact that
the electric fluid repels itself, and attracts all
other matter. Suppose there are two con-
ductors placed as in the following cut ; one

of them being a small conductor furnished
with three pairs of pith balls, placed near to
the prime conductor of a machine. Let that
prime conductor be charged by turning the
machine, and although the small conductor
does not touch it, it is evident from numerous
of the former experiments that it will be-
come electrical, in the same manner as the
feather did when the excited tube was held
towards it {Ex. 9). The fluid being re-
pellent of itself, and the end A of the prime
conductor being electrified plus, there will be
a superabundant quantity of the fluid at the
end A ; it will therefore repel the fluid of
B C from the end B. If B C be insulated,
this repulsion will drive the fluid from the
end B to the end C. As A does not touch
or give a spark or any appreciable quantity
of its extra fluid to B C it follows, what
indeed can be satisfactorily proved by other
methods, that it merely disturbs the fluid of
B C, driving it from the end B to that of
C. B therefore will be electrified minus, and
as the fluid driven from B is accumulated in
C, it must be evident that C would be elec-
trified plus, while the central point between
them would be neutral. This may be proved
by the following experiments : —

Ex. 160. Suspend from the small conductor
B C three pairs of pith balls, on fine linen
threads. Turn the machine very gently, so
as to cause the pith balls to diverge ; they
will hang as in the figure, showing a neutral
point where the balls are unaffected, and two
other points where the fluid is disturbed, and
which are therefore charged.

40

IGl. Hold an excited glass tube to the
pair suspended from B, they will be attracted
to the glass, showing themselves in a con-
trary state to the glass ; they are thereby
proved to be negative. Then hold the excited
tube to the pair at C, and they will be re-
pelled, showing that the excited glass and
themselves are both electrified alike, which
we know is positively.

162. Try this experiment with three con-
ductors, as in the annexed cut. When excited
as before, either by the proximity of a
charged conductor, or by an excited glass
rod held towards them, beyond the con-
ductor N, draw away the central conductor,
and also the excited rod, the central con-
ductor O will not be charged at all, that
marked P will be positive, and that at N
negative.

e^

c^^^^^^idbi.

163. When charged as before, as soon as
O is removed, place the conductor N, so as
to touch P. The disturbance of both will be
neutralized by each other, showing that the
quantity which is plus in one, exactly coun-
terbalances that which is deficient in the otlier.

164. While the last experiments are pro-
gressing, and before the conductors are taken
out of contact with each other, suddenly stop
the machine, or remove the excited tube, ac-
cording to that with which you are operating,
and the fluid will arrange itself as at first ; it
has become in a quiescent state, and conse-
quently no divergence of any of the balls will
take place. If there should be, it shows that
the conductor has become charged with ac-
cumulated, and not induced electricity, and
therefore all the pith balls will diverge with
the same electricity. It has in fact positively
received fluid, and not merely had that in-
herent in it disturbed.

165. If these three conductors instead of
touching each other, had been placed a little
apart, they would each have given the same
results as they now do together, as it must
be evident that they now act as a single body.
The same would be the case had the con-
ductors been ever so numerous, for according
to the laws of electrical induction, there can-
not be a body electrified positively without
the nearest body to it being electrified nega-
tively, this next body will in like manner act
upon a third, the third upon a fourth, and so
on. Negative and positive being always op-

posed to each other. Take the following
illustration of a number of spots of tin foil
pasted upon glass. Suppose them held near
to an excited electric, all the spots would be
endowed with positive and negative proper-
ties, according to the letters annexed to them.

In all cases of this kind, it must be evident
that an electric must interpose between the
two conductors, or they would act as one, so
in the experiment of the three conductors,
air which is an electric is between one and
another. In the condenser described in p. 15,
there is a layer of varnish between the plates,
so also in the electrophorus, the resinous
matter or cake interposes between the upper
plate and the under plate. In the circular
rubbing machine, and in the sulphur cone,
although excitation is carried on, on the one
side of a piece of glass, yet the effects become
apparent on the other side. In truth in-
duction takes place only because of the in-
terposing electric. In the air we have proved
that this effect diminishes according to the
square of the distance. In glass the exact
ratio is not stated, but in all probability it
follows the same law, making due allowance
for the solidity of gLss as a resisting medium,
and for its power of electric conductibility
compared to air. It is certain that the thinner
the glass is of all electrical apparatus, the
more powerfully it may be charged, and the
more easily excited.

The induction which so readily shows
itself on sliort conductors, is still more con-
spicuously exhibited in those of a considerable
length. For example, let us take the three
conductors of Ex. 163, and while acting, let
us add two more to them, the whole being
joined together. The last conductor when
there were three, became positive as we saw.
But the fifth is now positive, and tlie neutral
one is the third. The fluid when there were
three was only driven a short distance forward,
and its presence there prevented any further
action, but now with five conductors it is
driven twice as far as before, and therefore
offers less impediment to a greater effect.
It follows then that the longer the conductor,
the greater is the power or effect produced.
This being tried, will become evident, for
when there are five united conductors, or else
a conductor as long as the five, the pith balls
at the ends will diverge much more, by the
application of a certain quantity of elec-
tricity then when there are three conductors,
or one proportionably shorter. From this it
follows : — that the electric effect will be ex-

41

hibited much more strongly by long con-
ductors than by short ones. If the greater
electric effects are produced by very long
conductors, a question relative to their greater
or less diameter, or their greater or less so-
lidity, would naturally suggest itself. Some
experiments upon this subject will show us
that it is not those conductors that have the
greatest quantity of matter in their bulk, that
conduct electricity the best, but those which
have the greatest surface ; hence it appears
that electricity passes over the surface, and
accumulates there only. Yet in violent
transmissions of the fluid it appears certain
that the fluid passes through the whole sub-
stance ; when treating of the mechanical effects
of electricity, we shall see this abundantly
exemplified. At present we have only to
adduce an illustration or two of the ordinary
accumulation of the fluid upon the surface
of bodies, rather than of its passage violently
through them, and for this we have the law
of Coulomb — that the quantity of fluid ca-
pable of being made apparent by excitation
or transference is in proportion to the surface
of a body along which it passes, or upon
which it is accumulated. Thus a hollow
cylinder is always as efficacious as one which
is solid, and a large thin conductor will accu-
mulate more fluid than a small one of more
solid material. The power of a Leyden jar is
always in proportion to its extent of surface,
and not according to the thickness of the
coating, and so on in numberless other simi-
lar instances. The following experiments
have been adduced to show that in excited
bodies, or those which are charged with fluid,
the fluid is only to be found disturbed at
the surface.

166. Support upon a glass rod a wooden
ball, and bore various holes to different depths
upon its surface, as represented in section
below ; then support a wafer covered with
gold-leaf upon a very fine and dry rod of shell
lac. Charge the wooden ball by holding near
it an excited glass tube. "While it remains
charged, touch its surface with the supported
gilt wafer, which immediately hold to a very
delicate electrometer ; this will show that the
wafer has imbibed some of the electricity
from the surface of the ball. Again, pass
the gilt wafer quickly and neatly to the bot-
tom of one of the holes, withdraw it, and
upon holding it to the electroscope, no effect
w 11 be produced.

167. The electric ivell. — Place upon an
electric stool, a metal quart pot, mug, or
some other conducting body, nearly of the
same form and dimension, then tie a short
cork ball electroscope, that is two cork balls
suspended on a linen thread, to a silken cord.
Electrify the mug, and hold the electroscope
within it, when it will not be at all affected.

168. Instead of the electroscope in the
last experiment use a metallic ball, suspended
by silk ; electrify the mug and withdraw the
ball, it will be found not charged by its con-
tact with the inner surface of the mug, though
it may have been struck against its sides
many times.

Biot, the celebrated French electrician,
constructed the apparatus shown beneath.
It consists of a round metal ball, suspended by
silk and covered with two caps, each furnished
with a glass handle as represented, made of
paper and covered with tin-foil, and such that
when united, they accurately fit the surface
of the inner ball. Let there be communi-
cated to the ball any degree of electricity,
then let the two caps, held by their insulating
handles, be carefully applied to its surface.
Upon the removal of these caps, it will be
found that the whole of the electricity has
been abstracted from the sphere, so that it
will no longer affect the most delicate elec-
trometer, while the two caps will be found to
have acquired precisely the same quantity of
electricity which had at first resided in the
ball.

The next circumstance to be observed is
the effect of an extended or contracted sur-
face in rendering apparent a minute quantity
of electricity. It is not to be supposed that
the communication of a trifling amount of
force will affect a large body — or, that a
little fluid spread over an extended space
will be so apparent as if more concentrated.
In electricity, as in mechanics, the means
must be proportionate to the end to be
effected, and that which will influence sen-
sibly a small conductor will be unappreciable
on one which is larger. Thus electrical
intensity may be less, though the quantity is
the same. This is illustrated by the following
experiments of Biot, Coulomb, and Cavallo.

G

42

The figure beneath represents the ap-
paratus required. A is a roller of baked
wood, wax or glass, supported upon two rods
also of glass ; a strip of tin -foil reaches to
the central axis at the end farthest from the
handle, or else there is a fine wire which
reaches from the metallic ribbon or long slip
of tin-foil C, to the insulated electrometer
E F. G is a silk string attached to F. On
electrifying the cylinder, or rather the metal
coil E, the balls of the electroscope diverge ;
upon taking hold of the silk thread, and un-
rolling the metallic lamina from the cylinder,
the balls gradually collapse, thus indicating
a diminution of electrical intensity. Again,
winding up the lamina, the balls will diverge
as at first, making an allowance for a trifling
dispersion of the fluid during the experiment.

169. Make a number of pasteboard plates,
cover them with tin-foil, and suspend them
from each other by a metallic thread, a handle
of glass or a silk cord being attached to the
upper plate. Let the plates rest on each other,
and place the whole together upon the top of
a gold leaf electroscope, electrify them so

that the gold leaves diverge ; then gradually
draw them up by the silk thread at the top,
when the diverging will diminish in proportion,
and again increase when let down as at first.

170. Insulate a metallic cup, or any other
concave piece of metal, and place within it a
pretty long metallic chain, having a silk
thread tied to one of its ends. To a wire
proceeding from the cup suspend a pith ball
electroscope. Then electrify the cup by
giving it a spark with a knob of a charged
bottle, and the balls of the electroscope will
diverge. Lift up one end of the chain, when
the balls will collapse, let it down again and
they recede as at first.

171. Excite a long strip of flannel, or a
silk riband, by rubbing it with the fingers,
then holding the knuckle to it, take as many
sparks as the riband will give, but when the
riband or flannel has lost the power of giving
any more sparks in this manner, double or
roll it up. By this operation the flannel
appears to be so strongly electrical, that it
not only gives sparks to the hand brought
near, but throws out spontaneous brushes oi

I light, which appear very beautiful in the dark.

CHAP. VL

INFLUENCE AND DIFFERENT EFFECT OF BALLS AND POINTS.
ELECTRICAL AURA.

The preceding chapter, treating of the diff'usion of the electric fluid over the surface of
bodies electrified, took no account of the particular character of their terminations ; it was
supposed that they were all rounded off by balls, or globular terminations to the conductors.
Let any of the experiments of attraction and repulsion be tried at the same time that a
sharp-pointed needle is suffered to project from the conductor, or the end or side removed
from the cylinder of the machine, and it will be apparent that the fluid is thereby dissi-

43

pated, so great is the power possessed by points in dispersing the fluid, that a single needle
or pointed wire suffices to dissipate the whole fluid collected by a large machine. Hence
the reason why all parts of the electrical apparatus, which is to hold accumulated electri-
city, must be made round and smooth. As points have, in the cases mentioned above, the
power to dissipate the fluid, so if they are attached to any surrounding object within the
influence of the machine, they will draw it thence. It is for this reason that a row of points
is placed on the side or end of the conductor nearest to the cylinder, the fluid being thereby
attracted from the glass, to which it adheres rather strongly, to the prime conductor. We
learn also the necessity of removing from the machine all pointed articles, of whatever nature
they may be ; likewise persons who wear head-dresses, and other garments with sharp
points and edges. In electrifying a gentleman, and afterwards a lady, on a glass legged
stool, a very great difference is often perceptible in the strength of the spark which may
be taken from each, entirely owing to the difference of their dress. We have in electrifying
a lady frequently seen in the dark that the whole of the lace border of a head-dress has
been perfectly luminous from the dispersion of the fluid, when of course but very small
sparks could be obtained. A sharp pointed shoe is very apt to throw off the fluid, so is
also a cravat pin, a metallic chain, and the point of a watch key. No dispersive effects
however take place when the points of any of these articles are covered ; for it is not
merely sufficient that a point should be present, but that it should at all times project
beyond the general surface, or no effect is produced. The influence of points is easily
seen in the dark, and the very different appearances then put on by the electric light
proves the law of induction before explained, in a very perceptible manner, for even the
very appearance of the light at the point will immediately inform us of the nature and
state of the electricity of the body to which it is appended.

E.V. 172. Escape of the fluid to a hall—
Hold a ball towards the prime conductor of
a machine, when at a certain distance,
according to the strength of the machine, a
spark will pass between the conductor and
the ball.

173. Escape of the fluid to a point. —
Hold a pointed wire towards the prime con-
ductor, and the fluid will be drawn off; but
silently, and without a spark.

174. Hold a sharp needle at a few inches
distance from a charged conductor, and try
with the other hand to take a spark ; it will
be found that a spark will not pass to the
hand until the needle is withdrawn, although
the needle may have been held at double the
distance at which the spark would otherwise
have flown across.

175. Brush of electric light. — Present a
pointed wire to a conductor, which is electrified
negatively, a lucid cone or brush will be seen
diverging from the point, and the quantity
of fluid will be increased. This is best done
with a machine which has an insulated
cushion. In directions to work a machine
in page 30, it was recommended to hang a
chain from the cushion to the ground. To
try the above experiment, take away the chain
from the cushion and hang it to the prime

conductor — then hold the point towards the
cushion.

176. Star of electric light. — Hold a
pointed wire towards the prime conductor,
when in action, a star will be perceptible on
the point, and not a brush as before.

177. Attach a point to the outer side or
end of the prime conductor, and a brush of

I light will issue from it, while a star is seen
] upon all of the points which are towards the
i cylinder.

j 178. Remove the conductor for some con-

j siderable distance from the cylinder, brushes

I of fluid will start from the cylinder, and stars

I seen upon the points of the conductor. Place

I a pointed wire on both prime conductor and

cushion, and make the points approach each

other ; a star will appear on one and a brush

on the other, the conductor parting with its

fluid, and the cushion receiving it. The pre-

44

ceding will be the appearance in the dark
from the two points.

179. Place a row of conductors, as in Ex.
162, and let each be furnished with a point at
each end, all the points farthest from the
prime conductor will show brushes of light,
and all the others stars. The stars indicating,
as will be evident, the negative state, and
the brushes of light the positive condition.
The reason of these appearances is thus ex-
plained by Dr. Roget. " The diverging lines
on the one side, and their inflections on the
other, represent exactly the paths of particles
flowing out as from a pipe, and urged for-
wards as by a force which gives them such a
projectile velocity, as to prevent their spread-
ing out beyond a certain distance from the
direct line of projection. But this very ve-
locity will carry the particles, that happen to
have deviated most, somewhat beyond the
point to which they are attracted ; whilst the
attraction to this latter point will tend to
deflect them from the line of their path, and
gradually turn them back, so that they will
arrive at the point of attraction by very dif-
ferent paths, and even some by a retrograde
motion. Hence while, in the first case, they
form a diverging cone of rays, in the latter
they must be distributed on all sides of the
j)oint, like the rays of a star. The annexed
diagram will sufficiently illustrate this ex-
planation by representing the supposed course
of the particles of electric fluid, passing
through the air from the positive to the ne-
gative point."

The above reason is plausible, but scarcely
satisfactory, because it takes no account of
the quantity of fluids emitted or absorbed,
nor yet for the distance of the points from
each other, or the impulse with which the
fluid escapes. It also supposes two points
opposed to each other, without this there is
a difficulty in conceiving that the star should
be equally perfect in a variety of circum-
stances. The following explanation appears
more satisfactory. The electric fluid, by its
momentum, flies off from a positive or sur-
charged point in a brush, like fire from a sky
rocket. The negative point being a mere
receiver, collects the fluid from every thing
around, equally on all sides ; hence it exhi-
bits not a cone but a star of light.

180. Electric flyer. — Place upon the con-
ductor a pointed wire, and balance upon this
a cross or star of wires, every ray of which

is bent towards the end in the same direction,
as represented beneath. The fluid issuing
from these various points will turn the star
of wires round in the opposite direction.

A'o/e. — In the dark, the fluid from the
various points will resemble a circle of fire,
and this is rendered more brilliant if the ends
of the wires are tipped with tallow or sealing
wax.

181. Compound flyer, round- abbut, 8fc. —
A number of flyers may be made to revolve
at the same time, if made very light, and
delicately supported. A number of similar

contrivances may be made as a round-about,
such as is seen at fairs, provided the points
which are to give it motion are properly
placed — one among these is

182. The electrical inclined plane. — In
which a flyer is furnished with a small grooved
pulley at each end of an axis tluit bears it, it
is placed on two wires which are supported
by glass. W hen this is connected with a
moderately powerful machine, the flyer im-
mediately begins to turn round, and traverses
up the wires.

183. Electric flyer with bells.— This ap-
paratus is represented annexed. It consists ot
a stand with differently-toned bells arranged
upon it ; in the centre is a glass rod, and this
supports a flyer, which flyer has depending
from one of its arms a wire and a silk string
bearing a brass ball, (the only use of the wire

45

is to keep the string somewhat steaay, also
the opposite arm of the flyer should bear a
ball as a counterpoise for the weight of the
wire and string.) To use it, take away the
conductor of the machine, and put the flyer
in the same place as the points of the con-
ductor usually are, when it will turn round,
and the ball striking against them of course
rings the bells.

j\^7y/e._All these varieties of apparatus
turn roun.d the same way, whether electrified
positively or negatively.

184. Electric orrery. — This apparatus is
/seen beneath. It represents the sun, earth
/ and moon.. The earth and moon are balanced
exactly as in the last experiment ; they are
at their centre of gravity, upon a pointed
wire, bearing at its other end the sun;
this wire has a point projecting sideways near
its farthest extremity. The moon also bears
a side point, thus (every part being nicely
balanced,) the earth and moon revolve round
each other, and both together round the sun
— making one of the best possible illustra-
tions of the real motions of these heavenly
bodies. The whole apparatus may be 6 inches
long — the sun, &c., may be of wood.

jects through the head of the mill, ready to
bear the sails. Make the sails of paper with
a fine wire running along the back and end
of each, a point of it projecting beyond the
other edge. Let the centre of these sails be
a small ball of metal, or else wood or pith
gilt — fix the sails in this ball, and place the
whole upon the point of the needle. Upon
turning the machine the mill will revolve
rapidly. This apparatus may be across the
sails from one extremity to the other 4 or 5
inches — the other parts in proportion.

18G. Electric breeze or aura. — Bring an
excited glass tube near a point that is fixed
to the end of a positively electrified con-
ductor, and the luminous brush will be turned
out of its direction by the action of the ex-
cited tube ; if the tube be held directly op-
posite to the point, the brush will vanish.

187. Fix the point to the end of the ne-
gative conductor, the lucid star will turn
towards the excited tube.

185. Electrical windmill. — Make a wind-
mill of card or baked wood ; up its centre put
a wire, the lower end of which may fit a hole
in the conductor, the upper end must support
a needle put crosi^'ays, so that its point pro-

188. Efect of a point to the glass feather.
—Try tht Ex. 128 with the glass feather, and
while the filaments of glass are extending in
all directions by electrical repulsion, hold
towards them a needle; they will be repelled
from the needle, because the needle point
draws away their accumulated fluid, the fila-
ments thus restored to a natural condition
adhere to the neighbouring filaments until
they obtain a fresh supply.

189. Instead of a point in the last experi-
ment, hold a metallic ball towards the excited
glass feather, and instead of receding from

I the ball, the filaments of the feather will cling
I to it, because its fluid not being drawn off
I is attracted by the opposite state of the ball.
I The head of hair or divergent threads may be
I used instead of the glass feather.

' 190. Hold a point towards the electric
swan, and it will recede from the hand; hold
a ball and it will approach.

191. The diving ball. — Place a small pith
or cork ball upon a tin saucer full of oil,

46

electrify the saucer, and hold a needle towards
the ball ; the ball will plunge beneath the
surface immediately. To explain this, it is
to be remembered that oil is an electric. As
soon then as the needle is presented to the
ball, it draws away its electricity, which oc-
casions the ball either to go to the side of the
vessel or to the bottom of it for a fresh supply.

192. The travelling ball.— Excite the
brown paper of Ex. 4, lay it on a table and
place a pith ball upon it, a quarter of an inch
in diameter. The ball will run about until
it becomes charged by the electricity of the
paper. It will then stop, and if a needle be
now presented to it, the little ball will roll
away to another part of the paper. In this
manner the ball may be made to roll back-
wards and forwards for some minutes, or
until it has completely dispersed all the dis-
turbed fluid of the paper.

193. T/ie pointed canoe. — Make a boat or
canoe of cork or wood, and place a figure in
it, poising a large needle in the manner of a
spear, let this float in water, connected with
the prime conductor, and hold the hand
towards it ; instead of approaching the hand,
the boat will recede from it.

194. Fasten a blunt pointed wire, or still
better a point of wood to the prime conductor.
Turn the machine, and hold your face or the
back of your hand against the point, when a
breeze from the point will be very sensibly
felt. Do the same with a point placed on the
cushion, and a breeze will also be felt from
the point.

195. Instead of the face or hand, if you
place a lighted candle near either of these
points, the flame will be blown aside, by the
breeze issuing from the point.

196. Let a feather be driven about the
room by an excited glass tube, as explained
in Ex. 14. While so driving hold to the
feather a pointed wire, the feather will be
repelled, although there are here two bodies
near to each other, which by the law of in-
duction we know must be electrified difl'e-
rently, and therefore should be attracted.

To explain this, let it be remarked that air
is always blown from an electrified point,
whether that point be positive or negative —
a fact often brought forward as an argument
in favor of there being two electrical fluids,
though it seems very easy to explain the

curious phenomenon by other and more
simple means.

It is evident that the air in the neighbour-
hood of an electrified point must itself be-
come charged with electricity, no matter
whether positively or negatively. The fluid
is repellent of itself, the particles of air then
to which it is communicated become neces-
sarily repellent of each other, in the same
manner as the particles of sealing wax of
Ex. 146, or those of water in the Ex. 148,
149, &c. Being repellent these particles
escape, and the air rushing in to fill what would
otherwise be a vacuity, produces a re-action
suflicient to occasion the motion of the flyers
and other apparatus. The reason why the fluid
proceeds from the points in the form of a brush
is easily accounted for — the wire of which
the point is the termination is itself electri-
fied, and therefore repellent of any particles
similarly charged. The fluid in its escape
must naturally then choose such a path as is
the most open or free from repulsion, which
will naturally be that in front of the point,
and farthest away from the machine. In the
case of a negative wire it is somewhat diffe-
rent. The negative point, as before ob-
served, seeks the fluid from all quarters, and
in drawing the fluid, as in the former case,
it draws the particles of air, in which the
fluid is contained, from all directions. As
action and re-action are equal, it follows that
as many particles as are attracted must be
either absorbed or repelled — electricity is
absorbed by the negative point, but not air.
The particles of air then must be again thrown
off", and these, which before attraction were
in a natural electrical condition, have now,
owing to having had their fluid abstracted,
become negative. The wire and point being
negative also, the particles are thrown off" ia
a brush in the same manner as the positiv*
particles were from the positive wire.

In all the above experiments the point has
been free, and projecting from or towards
the electrified body, and also has had an un-
interrupted communication with the ground,
or with the body electrified. Were either of
these circumstances altered, the point would
not act as we have seen it, but rather in the
same manner as a ball would ; that is, the
fluid would either not be drawn off at all, or
it would pass away with sparks, or sudden
interrupted flashes.

197. Stick several needles into a piece of

cork or other matter, so that their points may

not be covered, place this mass of points .at

j the bottom of a tin mug, with smooth edges,

' electrify it well, and if the needle points are

i below the edge of the mug, none of them

will be luminous, showing that none are

giving off" the fluid.

45

198. Thrust a sharp pointed wire through
the centre of the rind of half an orange, so
that the rind forms a cup around it. Let not
the point project beyond the edge of the rind,
and holding it towards a charged conductor,
no effect will take place, except the general
attraction of the fluid for the whole of the
apparatus. Now project the point forwards
by little and little, then as soon as it emerges
from the rind, the peculiar silent action of
drawing off the fluid commences, and a star
of light becomes visible.

199. Drill in a brass ball, which is 3 inches
in diameter, a conical hole, which is about as
large as a farthing on the outside, and tapering
towards the centre ; drill a small hole through
the opposite radius of the ball to admit a
pointed wire. Let the wire project 2 inches
beyond the ball on the side of the wide opening
of the hole, and hold it to the prime conductor
when charged. Taking the ball which ought
to be of metal, or wood covered with tin-foil,
in one hand, and the blunt end of the pointed
wire in the other ; the projecting point will
draw away the fluid silently. Still holding the
ball steady, gradually withdraw the wire,
when it gets near to the surface of the ball, it
will take a small spark, and when drawn fur-
ther in as strong a spark as if the ball alone
were there.

200. Electrical cross. — Form a cross of two
thin leaves of talc, and paste upon them spots
of tin-foil, just or nearly touching each other,
and with a wire point at each end support
this very nicely, as represented, on two
wires. Place it near the prime conductor,
and turn the machine, when the fluid passing
from the centre to each of the points will
produce beautiful streams of light, constantly
in motion in consequence of the rotation of
the cross.

Note. — This cross may be made horizontal
instead of vertical. This experiment is given
in the Annals of Electricity, but we doubt its
success, as the points take sparks, and do not
throw off or attract the fluid in brushes.

201. Hold towards the ball of a charged
conductor a spiral tube, furnished with a ball
at the end, and contrary to the usual character
of a point it will take a spark. This is owing
to the interrupted nature of the conductor
which connects the point with the hand or
with the ground.

202. Support a pointed spiral tabe, as
represented beneath, and have a flyer affixed
to the upper end ; place it near to a charged
prime conductor, when the fluid passing into
the points turns the flyer on its axis. — Ann.
Elec.

203. To pierce a vessel of oil.— Partly fill
a thin phial with oil, cork it, and thrust a bent
wire through the cork, so that the lower end
of the wire shall be about ^ an inch below
the surface of the oil. Let there be a ball at
the upper end of the wire. Take a spark
from the prime conductor by the ball, holding
the phial so that the thumb rests on the out-
side of the phial opposite to the point. Al-
though the wire is pointed at the lower end,
yet the spark will be so strong as to perforate
the glass. The oil will be curiously agitated.
This expei'iment appears most beautiful when
made in the dark. After the first hole is made,
turn the end of the wire round towards ano-
ther portion of the glass tube, and a second
hole may be made in the same manner. The
spark appears larger when passing through
oil than when passing through the air.

Other effects of points will manifest them-
selves through every part of the subject.

48

CHAP. VIL

ELECTRIC LIGHT AND SPARK. LUMINOUS TRANSFERENCE.

The electric fluid shows itself in the several forms of a diffused light, of a brush, a star,
and a spark, which spark varies in intensity, so as to be at some times scarcely perceptible,
and at others, (when occasioned by the rapid progress of an immense quantity of the fluid;)
like a flash of intense brilliancy ; sometimes straight and undivided, at others long and
zigzag ; also of various colors and degrees of vividness, according to the nature of the
conductor whence it is taken, or the density and character of the air, or other electric
through which it passes. In the more gradual dispersion and weaker manifestations of the
fluid, no noise is perceptible, a mere phosphoric appearance presenting itself as in Ex. 1 7
and 20 ; and as may be tried also by any of the experiments of the last chapter ; for
example, if the flyer, Ex. 180, be made to revolve in the dark a circle of brilliancy will be
perceptible. Another effect is perceptible in Ex. 202. If a large quantity of fluid be
escaping from a point, a whizzing noise becomes apparent. With a little more forcible
emission of the fluid the whizzing becomes changed to a crackling, and the phosphoric
light to a series of minute sparks. The noise and brilliancy increases in proportion to the
impulse and quantity of the fluid, until a flash of lightning and a clap of thunder exhibits
the most violent effects of its sudden passage from one overcharged body to another in
its neighbourhood which by induction is dissimilarly electrified. These effects however
are only the same in the same circumstances. Thus a negative spark is usually red, short,
and straight. A positive spark is of a bluish white, long and zigzag. This only supposes
that it is taken in the usual condition of the air, and from one metallic ball to another ; for
in rarefied air the noise ceases, and that which would in the atmosphere have been a con-
centrated and rapid spark, becomes a series of large, long brushes of diffused fluid. The
same taken from different woods or other matters, or through various gases, becomes
changed in color, no less than brilliancy. The brilliancy is also very greatly influenced by
the distance at which the spark is taken. If the machine be put into action, and nothing
be presented towards the terminal ball of the prime conductor, the fluid will escape in
fitful flashes into the atmosphere around. If any round conductor be held in the hand, or
if the closed hand itself be held at some distance from where these flashes issue, they will
be seen to have a tendency towards it, and as the hand is made to approach to the prime
conductor, so they will take a determinate form, color, and noise ; first, when at the
greatest striking distance, they will appear as faint, blue, and very zigzag sparks, like
distant weak lightning ; bringing the hand a little nearer, the sparks are more vivid, and
consequently, whiter — they are thicker, well defined throughout their whole length, zigzag
as before, and attended with a louder and quicker snap. At a less distance still, the
brilliancy and snap is further increased ; while the zigzag character is by degrees lost, unti
at length the spark is so rapid as to be almost continuous, short, thick, and straight, as
we see in that dangerous, though rarely witnessed kind of lightning, in which the heavens
seem to burst, and pour down a short perpendicular stream of intense volume to the earth,
killing and destroying every thing within many yards of its passage.

Such is the electric spark, and it may be advisable to remark, before proceeding
further, how it is that the power of an electrical machine should be estimated. It is

49

common to hear a person observe, relative to some machine, that it will give a spark so
many inches long, without stating how such a spark is to be measured. If he take all the
forks of the zigzag into account, undoubtedly it will much increase the measured distance ;
but this is not fair — still less is it to measure the spark upon the excited cylinder, for here
the repulsion of the fluid from the overcharged conductor is assisted by the charged surface
of the glass itself, and the attraction of the negatively -charged cushion. The true length
of spark which a machine will give is to be measured by the distance between the termi-
nating ball of the prime conductor, and a metallic ball held in the hand, when approaching
them gradually to each other, and (the machine being in good action) a spark will pass
between them. By this means of measurement, the real power of a machine may be
known. The explanation of induction will have shown that the longest spark is always to
be obtained from the end of the conductor, and also that the conductor should be of a
considerable size. The sound is occasioned by the momentary agitation into which the air
is chrown by the passage of the fluid. Also the object which takes the spark should be
round, and presented quickly towards the conductor.

Ex. 204. To obtain a crir2.wn spark. —
Take a spark through a bpjl of box-wood,
and it will appear of a beautiful crimson.
This is better done with a sh'-n-k from a Leyden
jar, as it is only a very strong spark taken
exactly through the centre of the ball which
will succeed, and even then it is very apt to
pass over the surface.

205. A red spark. — ^xa.^ a piece of gilt
leather over a metal ball, and take a spark
with the surface of the leather, and the spark
will be red.

206. Green spark. — Use a piece of silver
leather instead of gold, and the sp:uk will
appear of a green color.

207. Red spark. —Take a spark from the
conductor with a wet cabbage or other large
leaf covering over the hand, and it will be of
a red color.

208. Place upon the conductor of a ma-
chine a little cup full of water, or else place
upon the table a tumbler full of water, with
a chain which reaches from the conductor so
as to electrify the water. If now a spark be
taken from the surface of the water by a
metallic ball, or still better by the finger, the
spark will be red.

209. Place a piece of ice on the conductor,
and take a spark with another piece of ice,
and the spark will be very red. Ice is,
when below 13° of temperature Fahr., an
electric, and therefore will not take a spark,
but in a room it would necessarily be covered
with a film of water. This would act suffi-
ciently as a conductor, so that a small spark
may be taken readily by this substance.

210. Yellow spark. — Lay upon a dry sheet
of white paper, a train of powdered charcoal,
and take as long a spark from it as it will
give, one end of the train being connected by

a chain or wire to the prime conductor, and
the other end having the knuckle or ball held
in the hand presented to it ; gradually approach
the ball to the charcoal, so that the fluid
may run along it, and the spark will be of a
yellow color.

211. Prismatic colors in electric light. —
Take a triangular glass prism, and hold it near
the eye, while any luminous experiment is
being performed, and the seven prismatic
colors, or colors of the rainbow, will become
evident, showing that the electric light is of
the same nature as that of the sun.

212. Brilliant blue spark through nitrogen.
— Pass a spark through a vessel filled with
nitrogen, and it becomes intensely brilliant,
and of a splendid blue color, equal to that of
burning brimstone. The apparatus, which is
convenient for trying experiments of this
kind, is as follows : — A is a glass receiver,
holding about a pint, it has a wire and ball
inserted in two opposite sides B and C. B is
capable of sliding backwards or forwards, so
that it may be made to approach or recede
from the other. The receiver is placed in the
pneumatic ti-ough, and is filled with the re-
quired gas, in the ordinary way practised by
chemists. For some gases a mercury or oil
trough must be employed. During the ex-
periment one of the balls must be connected
by a wire with the prime conductor as at D,
and the wire of the other held in tlv Land.

39

50

213. Spark through oxygen, whitish. —
Pass a spark through oxygen gas, and it will
be whiter than in the air, and also less bril-
liant. The effect in these two gases is singular,
the brilliancy of the spark being increased in
the nitrogen, which is not a supporter of
combustion, and decreased in oxygen, the best
supporter.

214. Spark through hydrogen, reddish. —
Pass a spark through a very strong small tube,
filled with pure hydrogen, and it will be of a
red color. In this experiment you must be
very careful that the vessel be entirely filled
with hydrogen, for if a small quantity of
atmospheric air or oxygen be present, ex-
plosion will ensue.

215. Spark through carbonic acid gas,
greenish. — Pass a spark through carbonic
acid gas. The spark will be very similar to
that in air, except that it will have a little
green in it. It is more irregular than in air.

\ 216. Spark through chlorine, whitish. —

Pass a spark through chlorine, and the sparks
are very white, and bright throughout, never
presenting those dark intervals that appear
in sparks drawn through air, azote, or other

217. Variously colored through coal gas.
— Use coal gas instead of the above ; with this
gas the spark is sometimes red, at others
green, and both colors often appear in the
same spark. The result is here worthy of
observation. Coal gas being a composition
of carbon and hydrogen, and the spark being
red with hydrogen only, and greenish with
carbonic acid gas, the nearest approach we
have to pure carbon in a gaseous state. Yet
not merely in the chemically united coal gas,
but also in the mechanical mixture of car-
bonic acid and hydrogen, both colors are
perceptible. It is to be supposed that the
gases become polarized and disunited by the
passage of the fluid through them.

• 218. No spark through acid vapors. — Use
a volatile acid, such as fluoric acid, nitric acid,
hydrochloric acid, or sulphurous acid. Pass
it up to the top of the mercury, and very
little light, if any, will be apparent, acids
being so good conductors, that the fluid passes
readily and invisibly though them and their
vapors. A mercurial trough, instead of the
usual pneumatic trough must be used in the
experiment, and in others where a gas or
vapor condensible in water is necessarily
present.

In proportion ns the rarity of any medium
is increased, w less intensity of electricity is
required to render it luminous, and a spark
becomes extended in proportion to (he rare-
faction of the air through which it is made
to pass. Thus if the fluid be only sufficiently

strong to cross an inch space in a vessel filled
with air, it will pass through 2 inches if the
air be exhausted one-half ; and 4 inches if
the rarefaction be continued to one-fourth
the original quantity, and so on to greater
amounts. It assumes a more diffuse arid
brush-like form, and a different and fainter
color ; passing through vapors, more or
less rarefied, will also produce other effects.

219. Indigo light through the Torricellian
vacuum. — Seal a short wire within one ex-
tremity of a glass tube of 30 inches long, so
that the wire may project a little within its
cavity, and screw a ball on the external end
of the wire ; fill the tube with quicksilver,
and invert it in a basin of the same ; a va-
cuum will be formed in the upper part of the
tube, which will occupy most space when the
tube is vertical, and gradually diminish as
it is inclined. A spark which in the open air
would pass through only ^ of an inch, will
pervade 6 inches of this vacuum with facility ;
and if the quicksilver be connected with the
ground, a current of faint indigo-colored light
will pass through the upper part of the tube,
whenever its ball is brought near an electrified
conductor.

220. Blue and purple light in vmtery
vapor. — Previous to the inversion of the tube,
let a drop of water be placed on the mercury
at the open end, and secured by the finger ;
whilst the tube is inverted, it will rise to the
top, and when the finger is removed, and the
quicksilver descends, the water will expand
and extend the vacuum, and through this
expanded vapor a current of electricity will
become luminous, and of various blue and
purple colors, accomjing to its intensity.

221. Beautiful green light in etherial
vapor. — Instead of water, use a itfi drops of
ether, invert the tube, and pass a stream down
it. If the Sf)ark be strong, the flashes will
appear of a beautiful green color.

222. Green color in hot mercurial vapor.
— Fill the glass with very hot mercury, or,
still better, suffer it to boil in the tube itself,
and then invert it. The color of the light
within, and which passes through the vapor
of mercury, will, if the tube be very hot, be of
a bright green color, and very brilliant. As
the temperature diminishes, it loses its vivid-
ness, and when cooled to 20° below zero Fahr.
it is invisible. It is then in fact a perfect
vacuum, as there is no air present, and the
vapor of the mercury which first filled the
tube is condensed.

223. Color altered by degree of ex-
haustion.— Admitting to the above a very
small quantity of air, and gradually and
slowly increasing it, the flashes are at fir.-t
green, then sea green, then blue, and then
purple.

51

224. Faint yellow in the vapor of tin. —
Make a vacuum by means of fused tin } the
electric light at temperatures below zero will
be yellow, and very faint indeed, requiring
almost absolute darkness to be perceived.

225. Reddish purple in vapor of oil. —
Make a vacuum in a similar tube with boiling
oil, the light will be of a reddish purple, and
much more brilliant than that through the
vapor of mercury.

226. Pure white light. — Make a vacuum
above chloride of antimony, by boiling it in
the tube. This salt boils at 388°. The light
is of a pure white and very brilliant.

227. Take an air pump receiver of 12 or
14 inches high, adapt a wire, pointed at its
lower extremity, to the top of the receiver,
letting the point project an inch or two in
the inside. Place the receiver on the plate
of the air pump, and electrify the wire at its
top positively. Whilst the air remains in the
receiver, a brush of light of very limited size
only will be seen, but in proportion as the
air is withdrawn by the action of the pump,
this brush will enlarge, varying its appearance,
and becoming more diffused as the air becomes
more rarefted, until at length the whole of
the receiver is pervaded by a beautiful blush
of light, varying its color with the intensity
of the transmitted electricity, and producing
an effect which is in the highest degree
pleasing.

AURORA FLASK AND TUBE.

An instrument is sold by the philosophical
instrument makers to show the passage of
the fluid through rarefied air, without the
employment of an air pump. It is repre-
sented at A beneath. Fig. B is also a similar
instrument varied only in form ; the descrip-
tion of the one will therefore serve for the
other. A, which is called the exhausted flask
or aurora flask, may be made of a common
oil flask, though sold usually of three or four

times the size. A portion of the thicker end
is covered with tin foil on the outside suffi-
cient in quantity, that when held by the hand,
the glass itself may not be touched. The
neck is fitted with a brass cap and ball, with
a pointed wire projecting inside. This ball
should take off and show underneath it a
screw, with a valve opening outwards, that
the flask may be partly exhausted of air. No
tin foil is necessary inside. B is a long wide
tube of glass, fixed to a foot, and furnished
with a cap and ball, and pointed wire at top,
with the valve at the foot. By means of the
valve in either of these instruments it is ex-
hausted partly of air, by means of the air
pump, then the ball being screwed on A and
the foot on B, both will be fit for use. B is
usually called the aurora tube, the appear-
ance presented when electrified being exactly
that ofiered by the aurora borealis in high
latitudes.

Ex. 228. To imitate the aurora borealis.
— Make the flask very hot before the fire,
hold it by the tin foil, and hold its ball to a
charged prime conductor. Very long and
brilliant flashes will pass along the partly-
exhausted flask. The same thing occurs when
the long tube is held to the conductor, or
placed on the table near the conductor. The
flashes will continue long after the removal
of the tube from the machine.

229. A result of the same nature, but far
more beautiful, is seen when the aurora tube
is 3 feet long and 4 inches wide, and which
has a wire through the upper part of it, that
may be pushed up and down ; two plates are
placed inside, one a fixture near the bottom,
the other moveable up and down by the wire,
so that the plates may be made to approach
and recede from each other. The fluid will
in this apparatus pass in a continued and
beautiful stream.

230. While you are trying either of these
latter experiments, place a hand against the
side of the receiver or tube, as the case may
be, and the fluid will be attracted by the hand
towards the side of the vessel.

231. Take the aurora tube B, warm it»
thoroughly exhaust it of air, and while at-
tached to the air pump, hold one hand at the
top, while with the other hand holding an
amalgamated leather, excite the outside of the
tube, faint flashes of light will appear in the
inside of the tube, showing that one side of
the glass is excited when the friction is ap-
plied to the other. The success of this ex-
periment depends entirely upon the degree
of exhaustion.

232. Exhaust the aurora tube B of air,
and fill it with nitrogen, the flashes of light
now seen will be of great beauty. Draw
away by a condensing syringe half the con-

52

tents of nitrogen, and the flashes will be of
a line white color, and present one of the
most brilliant appearances that the whole
science presents.

233. Light in rarefied gases. — Exhaust
the tube, and introduce oxygen, the flashes
will be now very close and compressed, and
of a whitish color, but not brilliant. When a
small quantity only is introduced, the form
and appearance are better, but still the ap-
pearance is not so good as with common air.

234. Invert the tube and introduce a very
small quantity of hydrogen ; the brushes are
very fine in form and distinctness, but of a
palish red color, and with a soft velvety ap-
pearance. When the gas is very much rarefied,
the flashes are of a pale green.

235. Instead of the above, use the coal
gas, and the brushes are short, strong, of a
greenish color, and difficult to produce,
unless very much rarefied.

236. Use now carbonic acid gas. This
produces a very poor brush, of a reddish
purple color.

The transference of the electric fluid in
the state of spark presents to us numerous
experiments equally beautiful, though very
difterent in character from those which we
have shown when the light passes through
different media. The length and brilliancy
of the spark being accordant with the strength
of the machine, or the degree of intensity
with which the conductor is charged, it fol-
lows, that the rapidity with which sparks
would be given off is also dependent upon
the same cause ; thus by the aid of a power-
ful machine we may produce so rapid a
succession as to illuminate a whole apart-
ment, and if we diminish their size we may
in the same proportion increase the number
of sparks in a given time ; hence the origin
of what are called luminous devices, luminous
tvords, &.C., and which are among the most
beautiful of electrical experiments. They all
are contrived upon the fact, that if you in-
terpose an insulated conductor between a
charged body and another, which is receiving
a spark from it, you change that spark into
two sparks; if you interpose two such objects,
you occasion three sparks, and so on ; that
is, the fluid having a tendency to fly off from
a charged conductor to the ground, or to a
negative bodynear it, takes always the nearest
course, and is not diverted from its path by
intervening conductors provided they are
insulated ; if they are not insulated, of course
they form the nearest passage for the fluid,
and it will go no farther than to the nearest
of them, when it will at once pass away.
The explanation of this effect will at once be
attributed to induction, especially as adverted
to under E^. 165. In making electrical

1 devices, the following rules are always to be
i borne in mind. 1st : That the sum of all the
! spaces on the glass, between one piece of tin-
i foil and another, must be much less than the
. length of the spark which the machine will
' give ; in fact, altogether this aggregate space
1 should be less than an inch. 2nd. The fluid
I always traverses from the prime conductor
■ to the earth, and will, other circumstances

• being equal, always take the shortest course.
j 3rd. If the spaces in any two lines of dots
' be greater than the distance between that
. line and the next, the spark will fly across the
1 lines, instead of going along both of them.
'■ 4th. The least possible space between one
I dot and another is sufficient, even if it be as
I fine as a hair. 5th, The lines must never
' cross each other, unless on different sides of

• the glass. 6th. When used they must be
I quite dry and warm.

I 237. Shot chain. — Cut a number of shots

I half in two, and string them on a thread of

! black silk, at the distance from each other

i and of the size shown beneath. Take 1, 2 or

: 3 inches in length of this chain, according to

the strength of the machine, and holding one

end of this in the hand, take a spark with

the other end. The spark instead of being

single will appear distinct at each interstice

between the shots, so that the whole has a

most beautiful and interrupted luminous

appearance.

238. Luminous spangles. — Sew amunber
of metallic spangles upon a black silk ribbon
very nearly to touch each other. Suffer a
spark to run along the spangles, and a beau-
tiful line of light will be visible. The ribbon
may be a foot or more in length.

239. Spiral tube. — This consists of two
glass tubes, placed one within the other. On
the outside of the inner tube are fastened,
with common paste, spangles of tin-foil,
(punched out of the sheet of tin-foil with a
small hollow punch ;) the two ends of the
tubes are wrapped round with tin-foil, and
cemented each into a brass cap, taking care
that the tin-foil at the ends, and the spangles
and the brass caps are all in contact with
each other. To use the spiral tube, hold one
end in the hand and the other apply to the
conductor, when a spark will pass along the
whole length.

V,..-"

240. 5"^^ of spirals. — This is an experi-
ment of extreme beauty. There are six spiral

53

tnbes set round a stand in a circle, the under [
part is covered with tin-foil, connecied with
each spiral, and with the lower stand, to
convey away readily the fluid. B shows a
glass pillar in the centre, and A a brass wire
terminated by balls, which turns freely upon
the top of B, so that as it revolves, it shall
come very near to each of the spiral tubes in
succession ; the top of A is placed so near to
a ball which hangs from the prime conductor
of a machine, that sparks may pass in rapid
succession to the centre of A. If while the
apparatus is thus placed, A be turned round
by the hand, it will communicate a spark to
each of the spirals in its rotation, and they
will rapidly be illuminated.

are better made without any frame ; if they
have a frame, it must be of baked wood.

242. Luminous crescent. — This is best
made by straight strips of tin-foil pasted on,
and connected at the edges as shown be-
neath, and then the places for the sparks
cut with a knife.

241. Devices on glass. — Procure a piece
of common window glass, 3 inches wide, and
12 or more long. Make a design on paper
of the device you desire to have ; lay this
beneath the glass ; then cover the upper
surface with common paste, and with the
point of a knife, or top of a pencil, place a
series of tin-foil spangles, according to the
figure you have drawn. Press the pieces
down so as to lie flat, then let it dry. When
dry, wash off the superfluous paste, and put
a brass ball or bullet at one end, when the
device will be fit for use ; the bullet or ball
may be prepared by holding it in a vice, and
cutting it about half through so as to admit
the edge of the glass. Upon holding this at
one end, and taking a spark by the other,
the device will be illuminated. These devices

, •'«•• ;~i« ,..« •<•• ««•• •«§• aKa aios {

,.: S § : : I s I 3 I f : I : I ; L

»««■ «««» ;.«a £».S 5..S %t,l Uiil r

Note. — It is usually supposed to oe ne-
cessary to make a cross cut at the luminous
places, and to peck out the two small corners
thus liberated. This, however, is quite un-
necessary, merely drawing the knife across is
quite sufficient. It may be advisable to state,
that after the strips are pasted on, they should
be suffered to dry, and the general surface
carefully washed with warm water before
cutting them across.

243. The following device is made on both
sides the glass ; the spangles being on owe
side, the straight lines on the other.

!V\ /\ /\ /\ /\ /\T

244. It is sometimes extremely difficult
to arrange the strips when both sides of the
glass are to have a certain portion, as in the
following star, where it is evident that the
fluid would not run round if the spangles
were placed all on one side, as it would at
once pass away to its destination, the hand.
It must however be made to travel over the

54

whole distance. By the different shading of
the cut, it will be seen what must be pasted
on the one side and what on the other.

245. Luminous word. — In the same man-
ner a word, such as electric fire, light, &fc.,
may easily be made. It is best dorte by
pasting the tin-foil in a whole piece over the
glass, and laying a flat ruler upon it, cutting
the various lines, and then tearing off the
tin-foil which covers the intervening places.
By this means the lines may be preserved
straighter than by the other method.

Devices of this kind may be further orna-
mented by colored varnishes spread over
them, which will cause the spark to be varied
in color, when seen on that side upon which
the varnish was placed.

246. Revolving spiral. — The following ap-
paratus is the contrivance of Mr. Sturgeon.
The figures beneath show the front and side
appearance of the apparatus, the same letters
applying to each. A A is the foot board.
B B an upright wooden support. C a staple
which forms with the top of B a support for

the axle and small pulley P. A cord passes
from this to the multiplying wheel W. S is a
glass stem upon the top of which is the wire
ring O O. The axis is terminated in form
by a brass ball, on the two opposite sides of
which are two short spiral tubes ; these are
put in motion by the wheel, cord and pulley.
If while the spiral is made to revolve, sparks
be taken from the machine by the ball shown
on one side of the ring O, they will pass down
the spiral tubes, and produce a most beautiful
effect. *•

CHAP. YIIL

THE LEYDEN JAR AND ELECTRIC SHOCK.

The year 1745 was famous for the most surprising discovery that had yet taken place in
the science of electricity. This was the wonderful accumulation of its power by glass, or
the means of concentrating its effects by the Leyden jar, as it is called, and which took its
name from Mr. Cuneus, a native of Leyden, who was led to its discovery as follows : —
Observing that electrified bodies, exposed to the common atmosphere, which is always
replete with conducting particles of various kinds, soon lost their electricity, and were
capable of retaining but a small quantity of it, he imagined that were the electrified bodies
terminated on all sides by perfectly dry electrics, and removed from the conducting influence
of the surrounding air, that they would be capable of attaining a stronger power, and of
retaining it a longer period. The easiest method that suggested itself was to inclose a
conducting body in a warm glass phial. He tried with common water in a phial, corking
the phial, and thrusting a wire through the cork, which touched the water. After taking
a few sparks from the machine to the wire, and holding the phial by the outside, he
removed it from the machine, and endeavouring afterwards to take out the wire with the
other hand he felt a shock immediately in his arms and breast ; this being quite unexpected
was a matter of great astonishment, and it may be added, terror also.

65

It was this astonishing experiment that gave eclat to electricity. From this time ;t
became the subject of general conversation, every body was eager to see, and notwith-
standing the terrible account that was reported of it, to feel the shock, and in the same
year in which it was discovered, numbers of persons in almost every country in Europe,
got a livelihood by going about and showing it. The'Leyden jar is nearly as simple now
as it was then, and easy as electrical instruments are to make and manage generally, this
is one of the most so. It has just been stated, that water was placed within the phial,
and the hand on the outside. These acted not from any peculiar virtue in the hand and
in the water, but merely because they were both conductors, and of course any other con-
ductors, if equally good, would be equally efficacious. We have shown that metals are the
best conductors of all ; it follows then that partly lining and covering the phial with a
metallic substance, as brass dust or tin-foil, will be still more efficacious, as well as more
convenient, as it leaves the hands at liberty and prevents the annoyance and dampness of
water. A Leyden jar then described as lined and covered with tin-foil, differs in principle
in no degree from Mr. Cuneus's bottle of water, and the explanation of the one therefore
becomes that of the other.

THE LEYDEN JAR

Consists of a glass phial or jar of any size,
it is usually made with a large mouth, for the
sake of convenience. The
lower part is lined with tin-
foil, to about 2 inches from
the top ; the outside is also
covered with tin-foil up to
£he same line, as is seen in
the cut. There is a wire,
with a ball at top, connected
with the inner coating. The
jar is now complete, and
being dried and slightly
wrarmed, is fit for use ; for
the greater convenience of
holding the ball and wire
tightly, the jar is usually
made with a wooden lid at
top, and a chain reaching
from the wire, which is fastened to the lid,
down to the bottom of the phial, where it
rests upon the inner coating. When there
is a lid, it should be made of baked wood,
and turned with smooth edges.

Ex. 247. To charge and discharge ajar.
• — Place the brass ball of a coated jar in
contact with the prime conductor, while the
outside communicates with the table, turn
the cylinder, and the bottle will in a little
time be charged. To discharge the jar, or
restore it to its natural state, bring one end
of a conducting substance in contact with the
outside coating, and let the other be brought
near the knob of the jar which communicates
with the inside coating ; a strong explosion
will take place, the electric light will be visi-
ble, and the report very loud. If it is coated
very low this part of the surface may be

charged very high, but a considerable part
of the glass is not charged at all. When a
jar is charged very high, it will often explode
or discharge itself over the glass from one
coated surface to the other ; or, if the glass
is thin, it will make a hole through it, and
swell the coating on both sides, the glass in
the hole will be pulverized, and very often a
variety of fissures will proceed from it in
various directions.

248. To receive the shock. — Charge the
Leyden jar ; then touch the outside coating
with one hand, and the knob with the other
The jar will be discharged, and a sudden pe-
culiar sensation will be perceived in the
wrists, arms, or chest, according to the size
of the phial. This is called the electric
shock.

249. To communicate the shock. — Let the
several persons who are to receive the shock
arrange themselves in a line or circle as most
convenient. Let them carefully join each
other's hands without gloves, let tne person
at one end of the line take hold of a chain
which is connected with the outside of the
bottle, and let the person at the other end of
the line touch the knob of the bottle when
charged. The shock will pass along the
whole line of persons. In receiving a shock
in this manner persons are generally unwil-
ling to be at the either end of the line, thinking
that it is stronger there than in the middle of
the line, but this is a great error, as they all
receive it equally, and would do so if there
were a regiment of soldiers receiving a shock
at the same time.

250. To pass the shock without feeling
it. — As shocks are not agreeable, the elec-
trician generally discharges the phial by means

ot what is called a discharging rod. This is
either a semicircular piece of wire with a ball
at each end, or else two wires with balls at
the outer ends, and jointed at the lower ends
where they are received into a socket, into
which a glass handle is fastened. Hold the
common discharging rod firmly, and dis-
charge a phial by it, he will not receive a
shock. If the phial be a very large one, or
if he hold it lightly, he will feel perhaps a
slight tingling of the fingers, when the shock
passes, but this is all. If he be furnished
with the glass handled discharging rod, or
jointed discharging rod, as it is called, he
may by setting its knobs at a proper distance,
discharge even the largest battery without
danger. It is usual for the sake of conveni-
ence to fasten a chain to one of the arms oi
the discharging rod, which communicates
with the outside of the phial.

251. To ascertain the intensity of a
charge. — Fasten the quadrant electroscope,
(described in page 39) to the conductor, or if
more convenient to the knob connected with
the inside of the phial. As this lattt-r becomes
charged, the stem and ball of the electroscope
will rise up until it attains 85 or 90°, when
the bottle will be fully charged, consequently
no greater effect will ensue ujion turning the
machine longer.

DISCHARGING OR MEDICAL ELECTRO-
METER.

A, bottle will endeavour to throw off its
electricity from the inside to the outside, the
more as it becomes charged with greater in-
tensity, as observed in Ex. 244, and if the
two coatings be placed so close to each other,
that the attraction between the two coatings
overcome the resistance of the glass, a dis-
charge necessarily takes place. On this fact
the discharging electrometer is constructed.
A is supposed to be a cross section of the
prime conductor of an electrical machine.
B is a brass cap, forming the end of the elec-
trometer. It is made with awire beneath to fit
the hole of the conductor. C is a bent glass
tube. Da brass ball at the end of it. E is awire
with a brcss ball at each end, which wire is
moveable backwards and forwards. When a
shock is to be taken, the ball E is placed at
a certain distance from the surface of A. A
is connected with the inside of the Leyden
jar, which communicates the shock, and the
chain is connected with the outside of the
jar. When the jar is charged to such a degree
of intensity, as to acquire force enough to

strike across from A to E, the discharge will
spontaneously take place. The ball at E
must be set at a greater or less distance from
A, according to the strength of shock re-
quired. If a shock is to be given to a com-
pany, when this electrometer is to be used,
tliey must form part of the circuit between the
outside of the bottle and the electrometer.

ELECTRICAL BATTERY.

A series of jars is called an electrical bat-
tery. This powerful instrument is so arranged
that all the outside coatings are connected
together by standing in a box lined with tin-
foil ; and all the inside coatings are also
connected by their wires meeting in a ball at
the top. It is charged and discharged in
the same way as a single jar, and has of
course precisely the same effect, but propor-
tionably more powerful.

BALANCE DISCHARGER.

For discharging a battery at a certain de-
gree of intensity an instrument is sometimes
used, in which electric repulsion is the acting
principle. This is represented beneath : —

A is a foot-board, supporting two glass
pillars B and G. C is a brass ball and
socket, fitting upon B, and by a hook at-
tached to it holding the chain H. The ball
C bears at top a brass arm and ball F, which
are fixed immoveably to it. Upon an axis
running throut^h C is supported the balance
D E also of metal. In order that this ba-
lance may play up and down so that E shall
be able to reach and fall upon G, a slot or
long aperture is made on two opposite sides
of C, wide enough for the wire to pass
readily. There is also a chain attached to

5/

the socket of G, marked I ; and a small
moving weight between C and E to be slipped
backwards and forward, as required. To
understand the mode of action of tliis valuable
discharger, it is to be remembered that bo-
dies when electrified similarly repel each
other in proportion to the degree of their
electrization. Now connect H with the
inner part of the battery, and I with the
outer, and see that the balance is loaded a
little, by moving the small sliding weight
between C and E. The brass part of the
balance connected with H will become
charged, and when sufficiently charged to
overcome the balance weight, the ball E will
be repelled downwards, and fall to G ; as
this is connected with tlie outside of the
battery it will be discharged by the contact
of G and E. It is to be remarked that
while repulsion will go on between F and E
attraction will arise between E andG, there-
fore there is a double force to drive down E.

Explanation of the shock. — The expla-
nation given of the phenomena of the Ley-
den jar is that of induction. Glass is sup-
posed to contain, at all times, on its two
surfaces, a large quantity of the electric
fluid, which is so disposed that if you increase
the quantity on one side the other must throw
off an equal proportion ; or, when one side
is positive, the other must be negative. Now,
as no more of the electric fluid can be forced
on one side than can go off on the other,
there is no more in the bottle after it is
charged than there was before ; the quantity
is neither increased or lessened on the whole,
though a change may be made in its place
and situation ; i. e. we may throw an addi-
tional quantity on one of its sides, if, at the
same time, an equal quantity can escape
from the other, and not otherwise. This
change is effected by lining parts of its two
surfaces with a non-electric, through the
mediation of which we are enabled to convey
the electric fire to every physical point of the
surface we propose to charge, where it exerts
its activity in repelling the electric particles
naturally belonging to the other side ; all oi
which have an opportunity of escaping by the
lining in contact with this surface, which, for j

that purpose, must communicate with the
earth. When the whole quantity belonging
to this surface has been discharged, in conse-
quence of an equal quantity thrown upon the
other surface, the bottle is charged as much
as it can possibly be. The two surfaces are
at this time in a state of violence ; the inner,
or positive side, strongly disposed to part
with its additional fire, and the outer or
negative side, equally desirous to attract what
it has lost ; but neither of them capable of
having a change in its state eflected, without
the equal and contemporary participation of
the other. That notwithstanding the vicinity
of these two surfaces, and the strong dis-
position of the electric fluid contained in one
of them, to communicate its super-abundance
to the other, and of that to receive it, yei.
there is an impenetrable barrier between
them ; for, so impermeable is glass to the
electric fluid, (though it permits one side of
it to act on the other,) that its two surfaces
remain in this state of contrariety till a com-
munication is formed between them, by a
proper, conductor, when the equilibrium is
suddenly and violently restored, and the
electric fluid recovers its original state of
equality on the two sides of the glass.

We shall be able to prove the truth or
error of this reasoning by the following
experiments.

252. To charge a sheet of glass. — The
principle of the Leyden phial is seen very

perfectly in a sheet of
glass, such as is repre-
sented. Tin-foil is to be
pasted on each side, to
/ ii \ within an inch or more
• I jii V of the edge ; fasten a
thread, holding a pith
ball, to the tin-foil on
each side with a piece of
wax ; connect one coat-
ing with the ground, and
louch the prime con-
ductor with the other,
the plate of glass will be
charged, and the pith balls fly out to some
distance ; connect the two sides together with
a wire, the shock will pass, and the pith balls
will become at rest.

253. Magic picture. — Procure a frame of
dry wood, and furnish it with a glass, as a
picture-frame usually is, cover this with tin-
foil, as inEx. 252 ; cover the back with a loose
piece of dark paper, or a thick dry paste-
board, cutting a small hole in the middle, in
order to bring through it a strap of tin-foil,
which is pasted upon the coating of the
under side of the glass, and reaches to the
frame ; now cover the tin -foil on the f;ice of
the glass with a picture of any kind, and the
instrument is complete. To use it, put a

8

piece of money on the picture, and holding
it by the frame where the tin-foil is, charge
the picture by presenting a ball from the
conductor to the money. When charged,
take hold of the frame by the other hand, at
some other part of the frame, and direct
another person to hold that part which you
have just quitted with one hand, and to take
off the money with the other. His attempt to
do so will discharge the sheet of glass, and he
will receive a shock in the fingers, while he
will be quite unable to take off the money.
This amusing apparatus is represented in the
following cut : —

2i>4. Electric pendulum. — Construct an
instrument of wire, with pith balls at the end
of it, as represented. Hang this on the
charged plate of glass, when it will vibrate,
so that its balls touch each side alternately,
and finally discharge the jar.

A charged jar may be handled with im-
punity, provided we are careful never to
touch the outside'and inside of it at the same
time, as may be easily proved.

255. To discharge a iar gradually with
the finger. — First, put the jar on an in-

sulating stand, then touch the outer and
inner coating alternately with the finger, and
a small spark will pass each time, and finally
discharge the jar.

256. To wipe out a jar when charged. —
Insulate the jar on a glass legged stool, being
careful not to touch the stool or outside
coating, either with your hand or clothing.
Take off the cover by the ball, only a small
spark will pass to the finger ; holding a hand-
kerchief in your hand, dip your hand care-
fully into the jar, wipe it out with the hand-
kerchief, and draw it carefully out again,
then put on the cover as at first. Now dis-
charge the jar in the usual way with the
discharger, and you will find that although
it has been thus handled, yet you neither re-
ceived any shock in wiping it out, nor was
the fluid silently dissipated.

257. To show that an insulated jar cannot
be charged. — Screw a Leyden phial, whose
coating is free from points, upon an insu-
lated stand, and place it so that its knob may
be in contact with the conductor, (taking
care that no conducting substance is near
the coating of the jar,) turn the cylinder
round a sufficient number of times to charge
the phial, then examine it with a discharging
rod, and you will find it had received no
charge ; which shows clearly, that except the
electric fluid can escape from one side of the
jar, it can receive none on the other.

258. To charge a jar negatively. — Insu-
late two Leyden bottles ; let their coatings
be in contact, and while you charge the in-
side of one positively, let a person, standing
on the floor, touch the top of the other with
his finger, and it will be charged negatively.

259. To discharge a jar silently. — Pro-
cure a Leyden jar, which has a hole in the
top of the ball, charge it, insulate it, then
screw a pointed wire on to the ball. This
will soon discharge the jar silently ; or the
orrery or flyer formerly described may be
substituted for it.

260. Electrical spider. — Make an object
in the shape of a spider — its body of cork,
with eight legs of white thread, about an inch

59

long, and suspend it by a thick black silk
thread. This will play between the knobs of
two phials, if one be electrified positively,
and the other negatively ; or will discharge
a phial, if suspended at a equal distance from
the knob at the top, and a knobbed wire
proceeding from the bottom of it.

261. Let a coated jar be set on an insu-
lating stand, and let its knob be touched by
the knob of another jar negatively electrified ;
a small spark will be seen between them, and
both sides of the insulated jar will be instanly
negatively electrified.

262. Fasten a pith ball electrometer by a
little wax to the outside coating of a jar,
slightly charge it with positive electricity, and
set it on an insulated stand, the ball will either
not diverge, or only a very little ; bring the
knob of a jar which is strongly charged with
positive electricity, near the knob of the
former, and the balls will diverge with posi-
tive electricity.

263. Let the same jar, with the pith balls
affixed to its outer coating, be slightly charged
negatively and then insulated ; bring the
knob of a jar, which is strongly electrified
negatively, to that of the insulated one, and
the pith balls will diverge with negative
electricity.

264. Charge a jar positively, and then in-
sulate it ; charge another strongly with ne-
gative electricity, bring the knob of the
negative jar near that of the positive one,
and a thread will pass between them ; but
when the knobs touch each other, the threads
after being attracted will be repelled by both.

These experiments seem to show that the
negative electricity is sometimes superinduced
on the positive, and for a few minutes after
theyare separated both will appear negatively
electrified, but if the finger is brought near
the knob of that jar on which the negative
electricity was superinduced, it will instantly
be dissipated ; a small spark will strike the
finger, and the jar will be charged positively
as at first.

265. To charge a jar by its own fluid. —
Let the rubber, and also the prime conductor
of an electrical machine, be both insulated.
Connect the inside of a Leyden jar which is
also insulated with the prime conductor, and
the outside of the same wire with the cushion.
Upon turning the handle, the phial will be-
come charged on the inside by the same fluid
which is taken from the outside.

266. Take two equal jars, with a quadrant
electrometer attached to the knob of each.
Place one of them in contact with the posi-
tive conductor of the machine, and the other
with the negative conductor. When the
machine is turned both jars will charge, and

to the same height, as may be seen by the
receding index of each electrometer. Re-
move the jars from the machine, and place
them on two separate insulating stands ;
connect their knobs by an insulating or
glass-handled discharging rod. No explosion
will ensue, although they are oppositely
electrified ; for their electricities depend on
the attraction of their outer surfaces, which
in this insulated state have no means of
communication. Connect the outer surfaces
by a wire or other conductor, and repeat
the experiment — an explosion will take place,
and both jars will be discharged

267. Hold a clean and dry pane of glass
by one corner, and pass it before a bail con-
nected with the prime conductor of the
machine, so that the ball may successively
come in contact with eveiy part of the mid-
dle of the pane of glass, whilst the finger or
any uninsulated substance is opposed to it
on the opposite surface ; by this process the
glass will be charged. Apply the discharging
rod to the opposite surfaces ; an explosion
will ensue. Make the contact with the dis-
charging rod again in another part of the
surface — another explosion will be procured ;
and in this way many are sometimes obtained
in succession.

268. Repeat the experiment of charging
the pane, and then place it between two
plates of metal of about half its size. On
the application of the discharging rod, but
one explosion will be procured, but it will
be louder and more brilliant than those pro-
cured from the uncoated pane. Hence it is
seen that the use of the metallic coating is
to connect the effects of every portion of
the surface of the jar, so that it may be
charged or discharged by the simple appli-
tion of the machine or discharging rod to
one portion of its surface

269. Place an uncoated jar beneath the
conductor of the machine, and suspend a
chain from the conductor so as to hang in
the centre of the jar ; on turning the ma-
chine the chain will move round, and apply
itself in succession to every part of the in-
ternal surface of the jar, which by that
means receives a charge. Apply the dis-
charging rod, and the chain will return over
the parts with which it has been in contact,
and thus by a few of its revolutions the jar
will be discharged.

270. Take a Leyden jar, coated on the
mside as usual, but with a coating of only
1 inch high on the outside ; during the
charge and discharge of this jar ramifications
of electrical light will be seen on the outside.

271. Jars with moveable coatings. — Pro-
cure a jar, with a double set of moveable tin
coatings, either of which may be adapted to

60

it at pleasure, the outer coating being a tin
case large enough to admit the jar easily
within it, and the inner coating a similar
case sufficiently small to pass readily in the
inside of the jar. The charging wire of the
inner coating should be surrounded by a
glass tube covered with sealing wax, to serve
as an insulating handle, by which the inner
coating may be lifted from the jar when that
is charged without communicating a shock
to the operator. Arrange the jar with its
coatings, and charge it, it will act in every
respect as an ordinary coated jar ; charge
the jar, and without discharging it, remove
the inner coating by its insulating handle.
If this coating, when removed, be examined,
it will be found not at all, or but slightly
electrified ; lift the jar carefully from within
its outer coating, and examine that — it also
will evince no sign of electricity. Fit the
jar up with the other pair of moveable
coatings, that have not been electrified, and
apply the discharging rod ; an explosion and
spark will ensue, proving that the coatings
are only the conducting materials from one
side of the glass to the other, and that it is
the glass itself on which the fluid is accu-
mulated. The following cut shows the usual
form of these jars : —

272. Diamond jar. — Take a bottle, whose
exterior coating is formed of small pieces of
tin-foil, placed at a little
distance from each other.
Charge this bottle in the
usual manner, and strong
sparks of electricity will pass
from one spot of tin -foil to
the other, in a variety of
dire(-tions ; the separation
of the tin-foil making the
passage of the fluid from
the outside to the table
visihle. Discharge this bot-
tle by bringing a pointed
wire gradually near the
knob, and theuncoated part
of the glass between the spots will be plea-
singly illuminated, and the noise will resem-
ble that of small fired crackers. If the jar
is discharged suddenly, the whole outside
isiiiface appears illuminated. To produce
».litse appearances the glass must be verv dry.

273. The double jar. — This instrument is
seen in the margin. It is used for various
experiments, and shows how
necessary it is to connect
the outside and inside of the
same jar together, before it
will be discharged. Place
the double bottle on a table
not insulated, and charge the
upper bottle A positively by
coimecting its ball with the
conductor. Tlie outside of
A therefore, and also the in-
side of B will be negative,
and the outside of B positive.
Now connect by the dis-
charging rod the outer coating
of B with the inner coating of A, and no
shock will pass between them. Again, con-
nect the outside of B with the inside of B,
and a shock will pass. Now connect the
inside of A with the inside of B, and a second
shock will be obtained. A series of bottles
may thus be arranged, and a series of shocks
obtained by one charge only.

274. To convey a shock to a distance. —
Amusement is often excited by giving a person
a small shock unexpectedly. This may be
done easily by a small Ley den jar holding
about halt a pint. It may be held in the
hand of the operator, without danger, by
its outer coating, he holding at the same time
a chain connected with the coating. The
other hand should hold a glass handled dis-
charging rod, connected with the other end
of the chain. If he touches a person with
the ball of the discharging rod, and also with
the knob of the small charged phial, a shock
will pass along the chain, and through the
person, without affecting the operator. It
is usual to employ for the above purpose a
coated director, which is a Leyden jar, made
of the following form, and coated in the
ordinary manner.

275. The electrical sportsman. — This ex-
periment is to illustrate the fact that a jar
will be liable to discharge itself when the
two coatings are too close to each other.
The inner coating of the Leyden jar is con-
nected with two wires ; one of which pro-
ceeds to the birds — the other proceeds to
within a short distance of the muzzle of the
gun. The birds are made of small bits of
pith, with a portion of feathers to each to
represent wings. They ai'e attached to
pieces of linen thread, 4 or 5 inches long.
The gun is connected with the outer coating
of the wire proceeding from it to the figure.

61

and a slip of tin-foil which is pasted alongj
the figure to the muzzle. Connecting the!
wire with the electrical machine in action f
it will of course become charged, during (
which time the birds will elevate themselves |
by electrical repulsion ; when the bottle is|
charged to a certain extent, the distancei
between the muzzle of the gun and ball near,
it will not be sufficient to restrain the pas-[
sage of the fluid, which will therefore pass
between them, occasioning at the same time
a flash of light, a loud report, and the
falling of the birds.

276. Cavallo's self- charging Ley den jar.
— Take a glass tube of about 18 inches in
length, and an inch or an inch and half dia-
meter. It is immaterial whether one of its
ends be closed or not. Coat the inside of it
with tin- foil, but only from one open ex-
tremity of it to about the middle ; the other
part remaining uncoated. Put a cork in at
the coated end, and let a knobbed wire pass
through the cork, and come in contact with
the coating. The instrument being thus pre-
pared, hold it in one hand by the naked
part, and with the other hand dry rub the
outside of the coated part of the tube, but
after every three or four strokes you must
remove the rubbing hand, and touch the
knob of the wire, and in so doing a little
spark will be drawn from it. By this means
the coated end of the tube will gradually
acquire a charge, which may be increased to
a considerable degree. If then you grasp
the outside of the coated end of the tube
with one hand, and touch the knob of the
wire with the other, you will obtain a shock,
&c. In this experiment the coated part of
the tube answers the double offiee of elec-
trical machine, and of Leyden phial.

277. Instead of a tube this instrumei.t
may be constructed with a pane of glass, in
which case it will be rather simpler, but it
cannot be managed so easily, nor yet charg( d
so high as the tube. A piece of tin-f( il
must be pasted only on one surface of the
pane, leaving about 2^ inches or 3 inches of
uncoated glass all round. .This done, hold
the glass by a corner, with the coated side
from you, and with the other hand rub its

uncoated side, and take the spark from the
tin-foil alternately, until you think that the
glass may be sufficiently charged ; then lay
the glass with its uncoated side flat upon one
open hand, and on touching the tin-foil with
the other hand you will receive the shock.

Adamses portable jar. — Mr. Adams, an
optician of the last century, invented the
following simple apparatus, whereby a shock
may be procured without t\id aid of an
electrical machine. A is the small Leyden
phial or jar that holds a charge. B is a bent
wire to discharge the jar. C is a varnished
ribbon to be excited, and comaiunicate its
electricity to the j ir. D are two hare or
other skin rubbers, which are to be placed
on the first and middle fingers of the left
hand.

278. To charge the jar. — Place the two
finger caps D on the proper fingers ; hold
the jar A at the same time at the edge of the
coating on the outside, between the thumb
and first finger of the hand ; then take the
ribbon in your right hand, and steadily and
gently draw it between the two ribbons D on
the two fingers, taking care at the same time
that the brass ball of the jar is kept nearly
close to the ribbon, while it is passing
through the fingers. By repeating this
operation thirteen or fourteen times the
electrical fire will pass into the jar, which
will become charged, and by placing the
discharger C against it, as shown in the
figure, you will see a sensible spark pass
from the ball of the jar to that of the dis-
charger. If the apparatus is dry, and in
good order, you will hear the crackling of
the sparks when the ribbon is passing
through the fingers, and the jar will discharge
at about the distance of ^ an inch from the
balls.

279. To electrify a door knob, ^c. — We
often hear of persons electrifying the handles
of doors, the pulls of bells, &c., yet this is
a very difficult experiment to manage. First
there must be a Leyden jar in readiness, and
this must be kept charged, which of itself is
difficult, then the outside of the jar must
have a wire connected with it, which reaches
under the carpet or otherwise, so as to be
concealed beneath a person's feet, when

6-2

standing at the electrified door, a circum-
stance almost impossible if in the street, and
not always easy of accomplishment in a room.
It is absolutely necessary that this wire should
be trodden upon by the person to be shocked.
The knob, knocker, or bell pull of the door
should be furnished with a second wire,
coming near to the ball of the inside of the
charged bottle, but not so near as to draw off

the fluid. It must be placed so that when
the knob is turned, the knocker lifted or the
bell pulled, this wire may come within strik-
ing distance of the bottle, which will conse-
quently be discharged. The fluid passing
along the wire, the knob to his hand, his
body, and finally the wire beneath his feet to
the outside of the bottle, when the circuit
will be of course complete.

CHAP. IX.

MECHANICAL, CHEMICAL, AND MAGNETIC EFFECTS.

The following experiments show the effects of the electric fluid when thrown against, or
passing through various substances, some of which it displaces, others illuminates, others
inflames, and a fourth kind of objects it rends to atoms in its passage. Many of these
effects induce us to attribute a material character to the electric fluid, and to believe that
it is a substance, imponderable as far as we know, as are light and heat, yet nevertheless a
matter rather than a power ; not like gravitation, and the centrifugal force, powers of nature,
but, like air, one of its solid but subtle elements, the occasion of numerous luminous
phenomena of common occurrence, and therefore considered by the ancients as elemental
fire : — whether it be so, present knowledge seems to confirm rather than to deny. Pro-
fessor Faraday, and other philosophers of equal learning, hold this opinion, and believe that
heat and electricity are but modifications of each other. In some respects their efTects
are identical, as many of the experiments of the present chapter will show ; in other respects
they appear perfectly distinct.

1. Fire will inflame combustible substances, so will electricity.

2. Heat is produced by friction, so is electricity.

3. The best conductors of heat are mostly also the best conductors of electricity.

4. Metals are melted by heat and also by electricity. On the contrary, it is alleged.
Firstly, that the electric fluid has a strong scent which simple heat has not. Secondly,
an increase of heat produces an increase of fluidity ; but bodies charged positively are not
thereby rendered fluid. So also, thirdly, a deprivation of the electric matter which a sub-
stance may contain does not cause the same congelation as that occasioned by abstracting
caloric from it. Fourthly, caloric not only heats but expands bodies, the electric fluid
does not produce this effect ; however long a body may be electrified, it neither becomes
hotter to the touch, nor more extended in dimensions. Fifthly, nothing analogous to the
nature of electrical attraction or repulsion can be discovered in heat.

It is said by those who deny the materiality of the electric fluid that it is only the
agitation of the air which produces its various effects, and that the compression of the air
causes those ignitions by the fluid, which we shall presently allude to. To confute this
opinion by positive experiment may be difficult, yet an appeal to the reason will soon show
the incorrectness of the opinion ; look at the lightning, and then say can this mighty phe-

63

nomenon be occasioned by any compression of the air which the mind can conceive.
Even supposing that the air would be thus compressed, how immense must be the power
which could thus compress it, and what is this power but the electric fluid. Besides this,
electrical appearances can be produced in a vacuum ; the motion of the fluid, also, is
inconceivably more rapid than the quickest motion of the air that we are acquainted with.

We shall endeavour to show that in some of the experiments the air is scarcely con-
densed at all, and would not produce the effect if it were. If the air were condensed, as
the fluid passes from the positive to the negative side of the apparatus, it would be con-
densed at that point only ; or if we suppose two electric fluids, rushing towards and
meeting each other, the concussion, and consequently the condensation, could only take
place at some point near to the extreme end, neither of which appear to be the case, as in
whatever manner the experiments may be varied, there does not appear to be any reason to
think that the inflammation takes place at any one point of the inteijjupted circuit rather
than at any other point. Besides which, when the inflammation of air and hydrogen gas
take place, the interruption of the circuit is extremely minute, and the air in a much
less quantity, so as to diminish very much the probability of this assumption.

These remarks and the experiments which illustrate them, clearly show that the
electrical fluid is different in its nature from those elements with which it alone can be
compared ; we are therefore bound until knowledge shall so progress as to explain more
fully the kingdom of nature to consider the electric fluid as a material body, imponderable,
and with properties peculiarly its own. The following experiments will afford much
amusement and instruction.

E.r. 280. Stand a card upright upon a
table, by a little narrow foot made of cork so
that but a slight force is necessary to overturn
it. Hold towards one side of this a point
connected with the prime conductor of a
machine. The breeze passing from the point
will blow down the card.

For experiments of this kind it is most
convenient to use a flexible tube, this is a tin
or brass tube, furnished at one end with a
joint and socket to fit into one of the holes
of the prime conductor, and at the other
with a screw, upon which may be fastened
either a ball or a point as different experi-
ments require. It is made usually of three
joints connected together by a piece of chain
covered with silk. The joint which bears the
ball or point, bears a glass handle ; so that
a person taking hold of this may move the
point about as he pleases, without destroying
its insulation. The following shows this con-

venient instrument, which is used for many
other purposes in electricity. The joints
may be 15 inches long each.

281. The card instead of being supported
upon a stand, may be suspended by a fine
wire, or a linen thread from the ceiling, when
according to the strength of the fluid the
card will be repelled.

282. Electrical ioa^.— Hold the charged
point towards the sails of a small vessel
floating in a basin of water. The impact of
the fluid against the sail, occasions the vessel
to float away from it. The sail should be of
white paper.

283. Electrical vane. — Make a vane or
wheel of paper, or thin pasteboard, (such as
is represented annexed) and suspend it by a
pin upon a piece of brass at the centre. Hold
the positive charged point towards one side

64

of it, and opposite the floats, when the wheel
will be put into rapid rotatory motion.

The wheel may Be suspended vertically,
instead of horizontally, and a system of
wheel-work put in motion by the same means.
Several of these contrivances were invented
by Mr. Ferguson, one of which is represented
beneath : —

TTW!lTiiwi!iiiii:iililiiiiil;iiiilliiilliiliiiiiiii:rai!:iiiiiiiii^

284. Fill a very small, thin glass tube with
water, pass a strong shock through it, the
expansion of the water, occasioned by the
passage of the fluid, will burst the tube and
scatter the water. This is a pretty experi-
ment if the tube is fitted up to a hulk, as a
mast. The shock would then represent a
flash of lightning, the mast would be struck,
and the rigging fall overboard, while by adding
one of the other experiments afterwards de-
scribed, the hulk may be made to take fire.

285. Water expanded. — Discharge a bat-
tery through a drop of water, previously
placed on the knob of one of its bottles ; the
whole will be instantly exploded into vapor.
The sparks will be much longer than com-
mon, and more compact.

28G. Quicksilver dissipated. — bend a
discharge to a greater or less distance through
one or more drops of quicksilver, the dis-
charge diff"uses itself into a fine spray, and
drives the drops into vapor ; part of it rising
into the air as smoke, the other part remaining
on the glass.

^287. Kinnersley^s air t?iermometer. — This
js an instrument tor showing the expansion
of air when an electrical
shock is passed through
the instrument. A is a
glass tube, upon both ends
of which a brass cap is
cemented. B a thermo-
meter open at both ends,
and with a scale attached
to the back. This tube
passes through the upper
brass cap, and nearly
reaches the bottom of the
under cap. F is a brass
ball and wire cemented to
the under cap, a simihu-
sliding ball and wire C
passes air tight through a
collar of leather on the
upper cap, so that its batt
may be placed at difterent
distances from the ball ot
the fixed wire F. The plate of the upper
cap is made to unscrew, so that colored water
may be j)ut in previous to the performance
of the experiment. By the rising of the
water in the thermometer tube over the scale
above the result of the experiment is seen.

288. Coward's electrical air thermometer.
— This instrument, a cut of which is seen
above, diflers but little from Kinnersley's
It is however more convenient in use. A is
the glass tube. C and D the balls for the
shock to pass, and B the thcrmomtter tube,

65

and which is bent upwards at the lower part.
Previous to using the instrument, fill the
tube B to the height of about 2 inches with
a colored fluid ; on the surface of which in
the long arm is to rest a light guage made
of quill, part being cut so as to act as a
spring, which will hold it at any part of the
tube.

289. To show the expansion of the air by
either of these instruments, pass a shock
from one ball to the other ; in consequence
of this the fluid will be driven up the tube.
To see to what extent, Mr. Kinnersley's elec-
trometer must be viewed at the time, but as
in Mr. Coward's the spring quill guage will
retain the position to which it has been
driven, this instrument may be inspected
whenever convenient.

290. Henlet/^s universal discharger, for
performing numerous electrical experiments,
it is necessary to use an instrument like the
following, which consists of a rectangular
wooden foot, upon the middle of which rises
a short wooden pillar, with a screw on the
side of it. Into this fits a shank, bearing a
small table 4 or 5 incnes in diameter, upon
the top of the table is let in a piece of ivory,
which it will be observed is a non-conductor.
The side pillars shown are of glass, except at
the top, where is fastened a metallic cap,
with a universal or ball and socket joint, or
some other joint which allows an equable
motion in every direction, to a short hori-
zontal socket above. Wires 6 or 8 inches
long pass through these sockets. Their outer
ends are terminated by rings, their inner
ends are blunt points, but covered with balls
which slip off and on. Thus by the con-
struction of the instrument, the balls may
be supplanted by points, and both one and
the other placed at any distance from each
other that may be desired. If one of the
rings or wires be connected with the outside
of a Leyden jar or battery, and the other
wire attached to one end of a discharging
rod, when the discharge of the jar or bat-
tery is made, the shock will pass through
whatever substance is placed between or upon
the balls o*f t*he universal discharger.

The table is in some experiments taken
away, and a small press put in its place.
This press is formed of two pieces of baked
wood, about 4 inches long and 2 wide ;

the lower one fixed on a
shank that fits the centre
socket of the discharger,
and the upper one con-
nected to the lower by two
thumb screws, as shown
in the cut, so that any
thing placed between the
boards of the press may be held there se-
curely while a shock is sent through it.

291. Electrical bomb. — The next figure
represents the electrical bomb, the firing of
which, if firing it can be called, where no fire
is, is accomplished by a strong shock of a large
Leyden phial or battery sent through it.
The bomb is made of ivory, with a small
short bore in it, so formed that the ball,
which may be of ivory or cork, can be im-
bedded a trifle more than one half in the
bomb, and a cavity of a smaller size be be-
hind it, with two wires entering this small
cavity. When a strong shock is passed
through these wires, the air withinside will
be agitated, and throw out the ball.

292, Fill the cavity or chamber behind the
ball with two or three drops of water, pass
the shock through, and the expansion of the
water will be so great as to throw out the
ball with greater force than before.

293, Paper rent. — Rest upon the table of
the discharger a piece of white paper, 4 or
5 inches square, and placing the balls about
2 inches from each other, send a shock along
the surface of the paper, when it will be
rent in pieces along the line which the fluid
travels.

294. To fracture sugar. — Place between
the two balls of the discharger a small lump
of sugar, and send a shock through it ; the
sugar will most likely be broken ; if not,
send a second and a third shock through it,
when, unless the shocks have been very small,
or the lump very large, it will be broken into
many pieces. If this experiment be performed
in the dark, the sugar will give out at the
time of the shock, and for half a minute
afterwards, a strong phosphoric light.

295. To pierce a card. — Pass a shock
through a card, by placing the balls of the
discharger on each side of and close to the
card, a minute hole will be pierced throtigh

66

the card, and what is very singular a burr or
projecting edge will be formed on each side of
the card. A shock may be passed through
three or four cards at once, and each have
its double burr.

296. Hang to the ceiling four or five sheets
of brown paper, and pass a shock through
them, the whole of the paper will be pierced
without being in the slightest degree moved.
Upon smelling the part of the paper which
has been pierced, it will be found to have
imbibed a strong odour analogous to that of
phosphorus.

297. Either of the above experiments, and
indeed most others may be performed without
the aid of the universal discharger ; for ex-
ample, if a few cards or sheets of paper be
held against the outside of a Leyden jar, and
one of the knobs placed close to the paper,
while the other knob approaches the inside
of the jar, the charge will pass and pierce
the cards.

298. Introduce two wires into a piece of
soft pipe clay, and pass a strong shock through
them ; the clay will be curiously expanded
in the interval between the wires. The ex-
periment will not be successful if the clay
be too moist or too dry.

299. Splintering wood. — Drill two holes
in the opposite ends of a piece of wood, which
is \ an inch long, and \ of an inch thick ;
insert two wires in the holes, so that their
ends within the wood may be rather less than
\ of ail inch distant from each other. Pass
a strong charge through the wires, and the
wood will be split with violence.

300. Coin stuck to ajar. — Charge a large
jar, and place a shilling or other piece of coin
between the knob of the discharger and the
coating of the jar.

301. Charge a very large jar, connect its
outside with one that is ten or twelve times
smaller, make a communication between their
inner coatings with the discharging rod, and
the small jar will be broken, the quantity o.
electricity transferred to it being beyond the
proportion of its size.

DIRECTION OF THE FLUID.

The mechanical effects of electricity have
been employed to indicate the course of the
electric fluid in the discharge, and thus to
confirm the proposition that assumes positive
electricity to be an accumulation of electric
fluid, and negative electricity to be a defi-
ciency, in opposition to the hypothesis first
proposed by Du Faye, that positive and ne-
gative are two distinct electric powers.

302. The direction of the electric fluid is
rendered visible when a Leyden jar, which

I has been rendered slightly damp by breathing
on it, is placed with its knob in contact with
the positive conductor of the machine in a
darkened room. When the jar is fully charged,
if the turning of the machine be continued,
the electric fluid will be seen to pass from
the inner to the outer coating over the un-
coated interval in luminous streams, pro-
ducing an effect similar to that of water
overflowing from the top of a vessel that is
kept constantly supplied. If the jar be re-
moved, and its knob placed against the ne-
gative conductor, the stream, when the jar
is overcharged, will evidently pass in a con-
trary direction, that is from the outer to the
inner coating. A certain degree of damp-
ness is necessary in this experiment, to pre-
vent the discharge of the jar by spontaneous
explosion, in which case the fluid passes too
rapidly from one surface to the other to ad-
mit the ascertainment of its direction. If
the moisture be not sufficient, divergent
brushes of light pass from the positive to the
negative surface at intervals, instead of the
continuous streams before described.

303. Discharge by withdrawing atmos-
vheric pressure. — Place a charged jar on a
small glass stand under the receiver of an
air pump. As the receiver is exhausting, the
electric fire will issue from the wire of the
jar in a very luminous pencil of rays, and
continue flashing to the coating till the air is
exhausted, when the jar will be found to be
discharged. The direction of the rays of
light will have the appearance of tending to
or verging from the jar, according as it is
charged positively or negatively.

304. The belted bottle.— Thh instrument
shows the passage of the fluid during the
charging of the bottle, and is but a modifi-
cation of the last experiment. Tlie coating
both inside and outside is put ou as repre-
sented. The belt on the outside is only put
in contact with the lower part of the coating
by means of the sliding piece on the outside.
The wire within is attached to the inside of
the bottom. In charging, the lower part be-
comes charged first, and the fluid will be
seen to pass upwards inside in flashes, while

67

if the connecting piece be withdrawn, the
fluid will be seen to pass downwards on the
outside from the belt to the lower part.

305. Place a lighted taper between the
wires of the universal discharger, they being
4 inches apart, and the flame midway between
them. Connect the coating of a small charged
jar with one wire, and bring its knob in con-
tact with the other ; if the charge be just
sufficient to pass the interval without ex-
plosion, the flame of the taper will be con-
stantly blown from the positive wire to that
which is negative.

306. Construct an apparatus, such as is
represented beneath. There being a small
metal cup at each side, supported by a glass
rod, and a lighted candle in the middle be-
tween them. Into each cup put a small piece
of phosphorus — connect one chain with the
prime conductor, and the other with the
cushion. Turn the machine, and the fluid
will pass from the positive cup to the lighted
wick, and driving this forwards against the
opposite cup will soon heat it so as to fire
the phosphorus, while there will appear no
emanation of the fluid from the negative cup.

307. The next figure represents an appa-
ratus similar to the last, except that it has
wires instead of cups, and a light vertical
wheel in the centre. Upon connecting the
wires with the diff'erent parts of the machine,
and putting it in motion, the wheel will turn
from the positive to the negative side.

308. Lay two straight sticks of sealing
wax on the table of the discharger parallel to
each other, so that the juncture of tlreir
rounded edges may form a groove ; on this a
large pith ball is to be placed, and the wires
of the discharger are to be arranged with
their points in the direction of the groove,
and at 4 inches from each other, the ball
being equally distant from both. On passing
a small charge from one wire to the other,
the ball will be driven from the positive to
the negative ; and this effect will be constant
if the terminations of the wires are pointed,
which they should be for these experiments
of transmission. If blunted wires be em-
ployed, the ball will frequently vibrate be-
tween them, and apparently render the
result equivocal.

309. Lateral discharge. — The following
cut represents a small conductor insulated,
and nearly touching a charged jar. There is
a second conductor, also insulated and nearly
touching the former, and in a straight line
with it. Make the discharge by a discharging
rod, from which a chain hangs that does not
touch the bottom of the jar, and the farther
conductor will receive an electric spark, which
quits it again almost at the same instant.
This electrical appearance without the circuit
of an electrical jar is called the lateral ex-
plosion. This may be tried in other ways.

310. Place on a dry board a little bran or
other light matter, and lay along it a wire
which forms part of a discharging circuit for
a large jar or battery. Upon making the
discharge, the bran will be scattered from its
place by the lateral explosion, and the greater
the force of the explosion, so much the
greater of course will be the scattering. It
is not surprising therefore, that heavy bodies
should be removed to considerable distances
by a strong flash of lightning. Dr. Priestly
imagined that this lateral explosion was pro-
duced by the explosion of the air from the
place through which the electrify discharge
passes. This lateral force is not only exerted
in the neighbourhood of an explosion, when
it is made between pieces of metal in the
open air, but also when it is transmitted
through pieces of wire that are not thick
enough to conduct it properly. The smaller
the wire is and the stronger the charge, the

68

greater is the dispersion of light bodies near
it. The following are examples of lateral
explosion.

311. Discharge a Leyden jar by means of
a common wire discharging rod, or one which
has no glass handle to it. Holding the wire
firmly, no sensation, or very little will be
felt in the hand, but hold it very lightly and
discharge the jar a second time, and a very
disagreeable trembling of the fingers will be
felt, owing to the action of the fluid laterally.
The same is the case when a spark is taken
from the prime conductor by a ball and wire
held loosely in the hand, though no sensation
is felt when the wire of the ball is grasped
firmly.

312. Let two wires be fitted into a groove
on the surface of a piece of smooth maho-
gany, ivory or sealing wax, in such a manner
that by sliding the wires backwards or for-
wards, their ends may be placed at any re-
quired distance from each other. When they
are about ^ an inch apart, place a thumb or
finger over the interval, and pass a charge
from wire to wire ; the thumb will appear
perfectly trawsparenc during the passage of
the spark beneath it, but no unpleasant
sensation will be felt.

313. Substitute a jar of water or any
colored fluid, in the place of the thumb ;
when the discharge is made, the fluid will be
distinctly and curiously illuminated.

314. Place the ends of the wires at the
distance of f of an inch, and over the in-
terval lay a thick piece of pipe-clay or of
pumice stone ; when the charge passes, these
opaque substances will appear perfectly
transparent.

The light of the electric fluid in passing
through an interval of air near to or in the
middle of a semi-transparent body, or one
which becomes luminous by the influence o»
an intense degree of ordinary light, com-
municates to it a luminous appearance some
times of some lengthened duration.

315. PhospJioric vapors. — Put a piece of
common phosphorus on the point of a wire
which hangs from the prime conductor of a
macliine. Until the machine is turned, the
vapors will ascend, but when the conductor
and wire are electrified, supposing the wire
hanging in the same position, the vapors are
carried downwards, and form a very long
cone of electric light, which is seen perfectly
distinct from it. When the electrization is
discontinued, the vapors ascend as at first.

31G. Phosphorus inflamed. — Place a piece
of phosphorus, as in the last experiment, or
in any other way projecting from the prime
conductor, and by means of a metallic ball
held in the hand take a spark from it. This

will inflame the phosphorus. A ball for all
such purposes as this should have a wire
handle to it, the wire being grasped, and the
ball held beyond the hand.

317. Candle re- lighted. — Instead of the
phosphorus, in the last experiment, substitute
a candle, the flame of which has just been
blown out, and which has a long snufF; upon
passing a shock or spark through the incan-
descent part of the wick, the candle will be
re-lighted.

318. Canton's phosphorus illuminated. —
Take some of the powder of Canton's phos-
phorus, and by means of a little spirits of
wine stick it all over the inside of a clean
glass phial, then stop the phial, and keep it
from the light. To illuminate this phos-
phorus, draw several strong sparks from the
conductor, keeping the phial about 2 or 3
inches from the sparks, so that it niay be
exposed to their light ; the phial will after-
wards appear luminous, and remain so. for a
considerable time.

319. Cut out in pasteboard, or so^t wood,
the figure of a cresce:^ or any of the planets ;
cover this equally witii the white of an egg,
beat up till it is (^^ite smooth, over which sift
the phosphorus through a fine lawn sieve,
then let it dry, and blow off all that is not
fixed by the egg. To make the experiment,
place the object in the communication be-
tween two directors, and discharge the jar,
when the whole will become beautifully lu-
minous ; care must, however, be taken to
hold the directors at a little distance above
the phosphorus, for if it passes through it,
the whole of the powder in the track of the
fluid will be torn off.

320. Place a small key on the phosphorus,
and discharge a Leyden phial over the phos-
phorus, and then throw the key off" from it,
and when it is exhibited in the dark the form
of the key and all its wards will be perfectly
seen.

321. Place a piece of dry chalk on the
table of the universal discharger, and adjust
the wires on its surface, with their ends at
1 inch distance from each other. Pass a
strong charge from wire to wire, and after
the explosion a streak of light will be evident
in the track of the discharge. It will con-
tinue luminous for several seconds.

322. Place upon or within a brisk fire, a
few oyster shells, and calcine them until they
cease to emit smoke, and appear burnt
through ; this may be from a quarter of an
hour to two hours, according to the strength
of the fire and compactness of the shells.
Many of them will exhibit the prismatic
colors when exposed to the lig4it of the sun.
Mr. Wilson excited some of these shells by
electricity as follows : —

69

323. Prismatic illumination. — Mr. Wilson
placed upon a metal stand, which was rounded
at top, and about ^ an inch in diameter, a
prepared shell, and near the middle, where
the color-making parts predominated, he
brought the ends of a metal rod, and then
connected the two metals properly with the
coatings of a charged phial, in order to dis-
charge the fluid. In this circuit there was
left, designedly, an interval of about 3 inches,
unoccupied by metal, and next one side ot
the glass. The discharge was made by com-
pleting the circuit with metal where the in-
terval was left. The shell at that instant was
lighted up to great advantage, so that all the
colors appeared perfectly distinct, and in
their respective places. These colors con-
tinued visible for several minutes, and when
they ceased to appear, a white purplish light
occupied their places, which lasted for a con-
siderable time. And notwithstanding this
experiment was repeated with the same and
other shells, the colors continued in their
respective relative situation, and nearly o(
the same degree of brilliancy. — Adams.

324. Pass a shock over the surface ot
native sulphate of barytes, this mineral will
appear luminous with a fine green light ; the
same is the case with the native carbonate
of barytes, but less brilliant. — Sinyer.

325. Pass the shock over or through dry
acetate of potass or succinic acid, or boracic
acid, it will appear green and very brilliant ;
with borax more faint. — Singer.

326. If the shock be taken over rock
crystal, it will be first red aud then white ;
if over quartz, it will be of a dull white. —
Singer.

327. To fire ether or spirits of wine. —
Procure a small metallic cup similar to that
presented in tJie following cut : — Fix it by its
stem to the prime conductor. Pour a small
quantity of spirits of wine into the cup or
still better of ether, take a spark through
the middle of the spirits, and they will be-
come inflamed. To insure perfect success at
all times, a thing absolutely necessary in a
lecture, let the cup be heated slightly before
being attached to the conductor. This will
occasion an evaporation from the spirit, and

the spark the more readilv inflame the
spirituous vapor.

If you have not a cup similar to the above,
a common table spoon, warmed and held in
the hand, will completely answer the pur-
pose. While so held full of spirit, the spirit
is to be held towards the ball at the end of
the prime conductor, so that a spark may
pass through the liquid.

328. Or, let a person standing on an in-
sulated stool and connected with the prime
conductor hold the cup with spirits in his
hand, and let a person on the floor take a
spark through them, and they will be fired.
The experiment answers equally well, if the
person on the floor holds the cup or spoon,
and the insulated person takes the spark.

329. The foregoing experiment may be
agreeably diversified in the following manner.
Let one electrified person, standing on an
insulated stool, hold the spirits ; let another
person, standing also on an insulated stool,
hold in his hand an iron poker, one end of
which is made red hot ; he may then apply
the hot end to the spirits, and even immerge
it in them, without firing them ; but, if he
put one foot on the floor, he may set the
spirits on fire with either end. The spirits
cannot be kindled by an insulated person ;
because, as the electric fluid cannot escape
through him to the earth, he is incapable of
drawing a spark sufficiently strong to inflame
them.

330. Hydrogen inflamed. — Make some
hydrogen gas, by putting a handful of iron
nails, or the same quantity of pieces of zinc
into a wine bottle ; to these add half a pint
of water and a wine glassful of sulphuric
acid. Have ready prepared for the bottle
a cork which fits it, and through which the
stem of a tobacco-pipe passes. The mixture
will soon throw up bubbles of gas; when it is
supposed that these have displaced the air of
the phial, cork it up, so as to suffer the gas
to pass out only through the stem of the
pipe. Here it maybe collected in a collapsed
bladder fastened to the other end of the stem,
or, if preferred, the bladder may be tied to
the top of the cork itself. The gas will soon
fill the bladder. When enough for use has
been collected, the stem may be broken, so
as to separate the bladder and the bottle,
and the part still attached to the bladder is
to have a small plug inserted in it, lest the
gas should escape. Procure some strong soap
suds and blow some bubbles by means of the
gas collected. Take care to touch these when
ascending with a ball fastened to the end of
the flexible tube described in page 63, the
tube being connected with the prime con-
ductor when the machine is in action, and
held by its glass handle, A spark witl thus

70

be given to the soap bubble, and the gas
inflamed. It will give a loud report at the
moment of inflammation.

331. Lighting a stream of hydrogen. —
While hydrogen gas is passing out of the
bottle in which it is generated take a spark
through the stream of the gas, by holding
the bottle in one hand, so that the top of the
pipe is near to the conductor, and taking a
spark from it, with a metal ball held in the
other, the gas will be inflamed.

332. Lighting the candles of a theatre,
8fc. — The carburetted hydrogen or coal gas
of the shops will answer the same purpose.
Let an apparatus be constructed similar
to the following, which represents two chains
A and B, attached to two balls projecting
from a wall by means of two glass rods.
The apparent candle is a tube, through the
top of which gas is issuing in a small stream.
If a shock from a Leyden jar be sent along
the wires or chains, however long those wires
may be, the gas will be inflamed, and the
apparent candle lighted. Several contrivances
of the same kind may be placed in diff"erent
parts of a theatre, when, if the chain passes
from one to the other, all the candles will
be lighted at the same moment. Be it ob-
served, that the interval between the balls
A and B should be very small, much less
than represented in the cut. Even i of
an inch is quite sufficient, and the whole
apparatus may be entirely concealed, if wires
are used instead of chains ; and supposing the
candle-shaped case be made of baked wood
or ivory, the wires may traverse up one side
and down the other, branching off" from the
lower part, where being in the shade thej
would not be observed.

333. Volta's hydrogen lamp. — Volta con-
trived a lamp upon the principle of the elec-
trophorus, which lighted hydrogen by a very
small spark. His lamp is shown in the fol-
lowing cut, where the instrument is seen in
perspective and in section. A is a leaden
bottle, which has a pipe from the top of it,
through the bottom, and extending some
distance below, as shown at B. The case is
divided into two compartments, the lower
one into which B dips is filled with water.

The bottle A is for the generation of hydro-
gen gas. The gas passes down the tube B
through the water, and occupies the tube and
cock E. Whatever surplus gas there is,
presses upon the surface of the water, and
drives that water up the tube C into the upper
vessel. The tube C ought to reach near the
bottom of the reservoir O. Whenever the
cock E is turned, the gas rushes out of a
small orifice H, where there are two wires
separated from each other by a small interval.
One of these wires is connected to the lower
plate of the electrophorus seen at F, and is
a fixture. The other wire G is connected
with the cock E, and meets the former wire
near enough to give a spark, whenever the
cock E is turned ; and as this also lets on the
gas, this is inflamed by the spark, and in its
turn lights the candle in the front of the in-
strument. The only trouble required to put
this ingenious machine in action is to rub the
lower plate of the electrophorus with a warm
flannel occasionally to excite it.

It is evident that by means of a small jet
of gas issuing from a minute orifice, as in
the above instrument, and a shock or spark
passing in like manner over a minute inter-
val in the jet, candles properly placed may
be ignited, and in any number, provided the
aggregate of all the spaces over which the
electric fluid has to skip be not greater than
the striking distance of the jar. Also it will
be remarked that a shock from a jar is better
than a spark for most experiments in which
apparatus are attached to walls, &c., as the
wires, &c. need not then be insulated, although
they necessarily must be so if a spark only
is employed.

334. Hydrogen pistol. — The simplest
form of the hydrogen pistol is seen beneath.
It consists merely of a tube of brass, about
\ an inch in diameter, and 5 inches long,
fastened on to a baked wooden handle, shaped
like that of a common pistol. Where the
trigger is ordinarily placed, is a short ivory
tube, which fastens into the brass tube, so
as to reach about half way across it. This
piece of ivory is pierced so that a wire may
pass through it. The inner part of the wir.i
is at a small distance from the ii.ner part of

71

the top of the tube, and the outer end of it
is terminated by a small ball. If then a
spark be taken by the barrel, and at the same
time that the finger touches the ball of the
trigger, a spark will pass from the tube to
the point of the wire inside, and thence to
the trigger to the hand.

A better kind of electrical pistol is seen be-
neath. A is a chamber, which with its tube is of
metal. A cap covers the end B. Upon taking
this cap off, and unscrewing the instrument
at C, the structure will be seen, as shown
below the cut of the perfect instrument. C
is the screw, one end of which fits upon A,
the other end is for the cap. In the middle
of C is a short glass tube D, through which
runs a wire E F, terminated by a small ball
at F, and bent upon itself at E, in such a
manner that the end of it very nearly touches
the screw of C, as shown at the point G.
The spark being received at F, runs along
the wire, leaps the interval G, where it fires
the gas, and finally passes to the outer tube
which is held in the liand.

335. To Jill the pistol.— Apytly the mouth
of the pistol to the opening of the bottle,
and the common and inflammable air will
mix together, because the former being
heavier than the latter will naturally descend ;
keep the pistol in this situation about fifteen
seconds, then remove it, and cork the pistol.
If the pistol is held too long over the bottle,
and is entirely filled with inflammable air, it
will not explode ; to remedy this, blow strongly
into the muzzle of the pistol ; this will force
out a quantity of the inflammable air, and
occasion a quantity of common air to enter
the pistol, which will then readily explode.

336. To fire inflammable air. — Bring the
ball of the pistol which is charged with in-
flammable air near the prime conductor, or
the knob of a charged jar ; the spark which
passes will fire the inflammable air, and
drive the cork to a considerable distance.
This air, like all others, requires the presence
either of common air, or else of vital air, to
enable it to burn ; but. if it is mixed with a
certain quantity of common air, an explosion
will take place in passing the electric spark
through it.

337. Mr. Cavallo's pistol. — Mr. Cavallo
recommends a pistol made in the following
manner, to those who wish to make experi-
ments on the explosion of hydrogen and
oxygen, or with known quantities of common
air and hydrogen. It consists of a brass
tube, about 1 inch in diameter and 6 inches
long, to one extremity of which a perforated
piece of wood is securely fitted ; a brass wire,
about 4 inches long, is covered, except its
ends, first with sealing wax, then with silk,
and afterwards with sealing wax again. This
wire is to be cemented in the perforation of
the wooden piece, so as to project about 2
inches within the tube, the rest is on the
outside ; that part of the wire which is within
is bent, so as to be only about the tenth of
an inch from the inside of the brass tube.
An instrument such as this forms part of the
apparatus to the next experiment,and a shock
passing from C to D inflames the gas within.

338. To inflame a bladder of gas. — Pro-
cure a plug of baked wood or ivory, about
the size of a large cork, and insert in it two
wires, at about ^ an inch distance from each
other, as is shown at A and B. At the lower
end the wires are to approach to within ^ of
an inch of each other, at the upper end they
may be turned into loops or rings, that the
whole may be hung up to a ceiling or wall,
Dy a silk cord, and the loftier the ceiling, or
more distant the wall, the better. In the
middle of the ivory let there be a third hole,
not stopped by a wire, in order that a bladder
may be filled with hydrogen gas by means
of it. A plug must be ready to fit it. Tie
a bladder tightly to the ivory tube, fill it with
hydrogen gas, mixed with common air, plug
up the hole where the gas entered, hang up
the bladder, connect two chains to it, one to
each of the wires, send a shock through the
whole, and the gas will be inflamed, making
a terrific explosion.

.-^'^

339. The magic vases. — This amusing
piece of apparatus is seen annexed. The
structure is evidently upon the principle of
the electrical pistol. The two vases A and B
have each a hollow brass chamber at top,
part of the side of which is cut away in one
of the figures to show the wire withinside.
The wire is continued downwards through
the entire stem, and connected with the chain
at the bottom. To use the vases, load them

72

in the same way as the pistol was loaded
with hydrogen gas, and cork thetn up ; after
which, connect the tops Fand G together by
a chain, as represented ; also let the chain E
be attached to the discharging rod, and the
chain D to the outside of a charged jar.
Upon making the discharge, the fluid will
pass up the stem of the vase connected with
E, pass out at the end of the wire, across to
the side of the chamber, setting fire to the
gas within and throwing out the cork. It
thence proceeds by the chain to the outer
case of the other chamber to the point of its
wire, inflaming the gas in the other vase, and
downwards out at the foot along the chain D.

If the chain at top be changed to a wire
a mile in length, so that the fluid may pass
the whole of that distance, yet the rapidity
of its motion is such, that the two chambers
of gas will explode so simultaneously as to
be heard but as one report. A variety of this
experiment, and which occasions considerable
amusement, is made by asking a person to
hold the vases one in each hand ; when the
shock is passed he will of course feel it, as it
will pass through his arms, and being accom-
panied with a loud report, it will, though
trifling in itself, mostly occasio!i coiisiderable
alarm to the person receiving the shock, and
equal amusement to the bye-staViders who
know that his alarm is groundless.

340. Rosin inflamed. — Wrap round one of
the balls of a discharging rod sotne tow, let
it lie loosely, and when tied on dip and roll
it in powdered rosin, discharge a Leyden jar
with this discharger quickly, when the rosin
will be inflamed.

341. Fill a flat porcelain dish with water,
and on the surface of the water strew a quan-
tity of powdered rosin ; place two wires on
the opposite sides of the dish, with their
ends near the surface of the water, and at 4
or 5 inches distance from each other ; pass
the charge of a jar from one wire to the

other, and the resin in the track of the ex-
plosion will be inflamed.

342. Rosin house or fire house. — The fol-
lowing cut shows what is commonly called
the rosin house, but it is not so likely to
succeed as the simple means of firing rosin
first given (in Eoe. 340.) The whole external
case is of tin, painted in the front according
to the fancy of the maker. Attached to the
chimney and side of the house is a glass tube,
terminated by the brass ball A, with which
is a wire proceeding down the tube into the
house, where it is terminated by a second ball
B. Through the opposite side of the house
is a second glass tube, wire and two balls,
marked at C and D. The wire of this part
is capable of sliding backwards and forwards,
that the balls wilhinside may be made to
approach each other more or less according
to the strength of shock to be passed through
them. The balls C and D are loosely covered
with tow, and dipped in or sprinkled with
powdered yellow rosin. When the shock is
passed from A to D, the rosin will most
probably be inflamed.

343. Gunpowder fired or scattered. —
There are several ways of firing gunpowder
by means of electricity, but it is only to be
done with absolute certainty when the fluid
is made to pass through a portion of water,
or other conductor which is sufficiently im-
perfect to allow the fluid to pass slowly along
its course, as it appears than when the fluid
passes with its accustomed rapidity through
metallic conductors, with but a small space
of air intervening, it has not time to ignite
the powder. The latter is therefore scattered
but not inflamed, and even when the powder
is tightly compressed into a cartridge or
rammed in a cannon, the firing of it is by no
means certain even by a very powerful bat-
tery, whereas by making a minute quantity
of water a means of communication l)etween
the diff'erent sides of the jar or battery em-
ployed, a very small charge, and indeed a
very small jar will be sufficient We have
often failed in firing gunpowder by a large
battery according to the old method, and
always succeeded by the method recommended

73

by Mr. Sturgeon about to be described, even
with a Leyden jar holding no more than a
pint. It may be important to consider these
various methods, as the right understanding
of them may assist in maturing an applica-
tion of this science lately introduced, namely,
the inflammation of charges of gunpowder,
intended for the blasting of rocks.

344. Fix a small cartridge on a metallic
point, which is fitted to a wooden or glass
handle ; make a communication from the
wire to the ground, then present the cartridge
to the knob of the phial, and the gunpowder
will be fired by the passage of the electric
stream through the cartridge. — Adams.

345. Electrical cannon. — The following
cut shows the electrical cannon. The ball at
the top has a wire attached to it which passes
down a short tube of ivory into the chamber
of the cannon, in the same manner as in the
hydrogen pistol. The cannon which has a
small bore is charged in the usual maimer with
gunpowder. The wire of the ball is pushed
down to its place, and when the point of the
wire is within a short distance of the lower part
of the bore it is properly prepared. The
outer part of the pistol is connected with the
outside of the charged phial, and by making
a connexion by means of the discharging rod
with the inside or knob of the bottle, the
charge will pass, and sometimes intiame the
gunpowder.

ball at one end, and screwed into a brass cap
at the other. B is a glass pillar. C a chain.
D a metal stand. E a piece of linen thread
dipped in water, connected with D, and with
the chain F. To use the instrument, place
a little gunpowder upon the top of D. Wet
the thread E. Connect C with the outside
of a Leyden jar, and F with the inside of
the same by the discharging rod. When the
shock passes, the gunpowder will bo inflamed.

347. Electrical powder-house. — The fol-
lowing cut shows the apparatus so called ;
one side is removed to show its interior.

34G. Sturgeon's firing of gunpowaer. —
Construct an apparatus as shown in the fol-
lowing cut, where A is a wire with a very small

It is made of seven pieces of wood, sn
united together by hinges, that when the
powder withinside is inflamed the whole of
the sides will fall down flat with the table.
A represents an ivory cup filled with very
dry gunpowder, having a wire through each
side, and nearly meeting in the middle ; a
shock is passed from P through a piece of
wetted thread B, then through the powder,
and out again to the chain N.

348. Electrical fort. — The next cut re-
presents a fort of baked wood with three
cannons. They are so connected, that if a
shock be passed from G to Y, it shall pass
through all the cannons, at the same time
there shall be such a disruption of contiguity
j as that the gunpow^der with which the can-
j nous are fired shall receive the shock ; and
I if, as we have before observed, a string dipped
j in water, or a plate of water be made a part
I of the circuit, it will at the same time be
j inflamed, and in each case so instantaneously,
! that the various cannons, however many of
Ihem there may be, will go off, with but a
single report. The chain G proceeds to C.

10

74

where it enters the cannon by a wire passing
through a small piece of ivory. The outside
of this cannon is connected with the wire E.
This passes to the outside of the next cannon
B. A nozzle of ivory in the touch-hole of B
conveys the circuit to the touch-hole of the
cannon A, the outside of which leads to the
chain F. The wire between A and B is sup-
posed in the cut to be supported by a short
glass rod, or a stick of sealing wax, between
the two cannons. The wetted string may
be attached to either end as may be most
convenient.

349. Gunpowder scattered. — Use the
same apparatus, and pass the shock through
it in the same ma;;ner as in the last experi-
ment, but take the thread away and substi-
tute a wire or cliain in lieu of it. Upon the
shock passing, the gunpowder will be scat-
tered, but not inflamed.

350. Gun2)owder inflamed by a shock
thronyh water. — TheEjr.34G may be varied
by adopting the following apparatus, and
which is so plain as scarcely to need an ex-
planation. The gunpowder is placed in an i
ivory cup, with two wires at a short distance
from each other in the centre chamber, one
chain leads to a director or discharging rod
ready to discharge the bottle, the other dips
into an earthenware dinner plate, full of
water. The gunpowder will be fired when
the shock passes.

nected by an iron chain which passes through
the tube. Furnish it with a wooden handle.
Discharge any Leyden jar with this dis-
charging rod, and the chain will be beauti-
fully luminous.

The following experiments are notinstances
of combustion, but are so closely connected
with the part of the subject we are now con-
sidering, that they may be introduced, if not
with propriety, at least with convenience.

351. The chain illuminated. — Form an
iron chain by cutting wire into lengths about
2 inches each, and turning up the ends, link
one piece to another ; hang this around a
room by silk strings, and pass a shock along
it, when it will appear beautifully luminous
at every link of the chain ; ap])earing like a
continued line of the most brilliant star-like
sparks.

352, The luminous discharger. — Bend a
tuhe of glass into a semicircle, put a brass
cap on each end, and let the caps be con-

353. Spiral illuminated. — Take a round
board well varnished, and lay on it a chain
in a spiral form, let the interior end of the
chain pass through the board, and connect it
with the coating of a large jar ; fix the ex-
terior end to a discharging rod, and then
discharge the jar ; a beautiful spark will be
seen at every link of the chain. The chain
may be sewed on in order to retain it in its
position.

354. Marks impressed on paper. — If in-
stead of using a board for the nbove experi-
ment, we lay the chain either in a spiral, or
any other manner on a sheet of dry white
paper, supported by a book, when the shock
is j)assed, the chain will he illuminated as
before, and will leave a black burnt mark
upon the paper at every link of the
chain.

355. Luminous board. — Procure a board
of any length, and send it to a baker's, to be
baked for two hours ; afterwards jilnne it,
and lay along it, seven, nine, eleven, or thir-
teen strips of tin-foil, an eighth of an inch
wide. These slips are to be put on and con-
nected together at the ends, exactly in the
same way as the strips upon the glass in Ex.
245, except that they are to be put on with
glue. The spaces between the slips being care-
fully cleaned off immediately with warm water
and afterwards wiped dry. Draw with chalk
any desired word or sentence upon the slips,
and with a penknife cut through the tin-foil
slips wherever a spark is desired to be. Be
the cut ever so minute, provided it pass quits
through the slip, it will suffice. Before use,
let the board at all times be well dried by
standing at the fire for some hours, as the
glue will be very apt to attract moisture from
the air. Pass a shock from one end of the
board to the other, and the whole will become
luminous from end to end. We have by this
means sent the shock of a gallon Leyden jar
through an extent of 180 feet, illuminating
four boards, with the words " Good night,
all's well," in well proportioned letters, 13
inches high, and by the same shock also

75-

rendered luminous 300 feet of iron chain,
and fired a bladder of gas in the distance.

356. Eggs illuminated. — This is usually
done by means of a little apparatus called

the egg stand, and which
is represented in the mar-
gin. This consists of a
wooden frame, with a piece
of metal let into the bot-
tom ; a chain attached to
this is connected with the
outside of a Leyden jar.
There are three wooden
slides to hold as many
eggs. A wire and ball
passes through the upper
part of the frame, so as
to touch the top egg, and
the eggs are lo touch each
other, A shock is passed
through the eggs by touching the upper
ball with a discharging rod, which reaches to
the inside of the charged jar, whose outside
is united to the chain at bottom. The eggs
will become beautifully luminous, and the
shock in passing will make a sound as if the
egg shells were broken, as indeed they will
be if the shock be large. A quart jar is
quite sufficient for this experiment. The
eggs, if eaten immediately, will have a
strong taste of phosphorus ; and will very
soon afterwards become putrid, that is to
say, in two or three days. When broken,
the white and yolk will be found completely
interna ingled with each other, if several
shocks have been passed through the eggs.

357. Illumination of oranges. — Substitute
three oranges for the eggs of the last experi-
ment, and send the shock through them ; they
will appear luminous. As oranges are not
good conductors, the experiment succeeds
best when the upper wire is made to pene-
trate the topmost orange, and when there is
a short piece of wire between every two, it
being thrust about half an inch through the
rind of each. A single orange may very
conveniently be illuminated by thrusting
through its sides the points of the wires of the
uni?ersal discharger.

The most remarkable effects of combustion
that are produced by electricity result from
its action on metals and their oxydes.

358. Gold leaf melted. — Place a strip oi
silver or gold leaf about h an inch wide on
white paper, pass a strong shock through it,
the metal will disappear with a bright flash,
and the paper will be stained with a purple
or grey color.

359. Take three pieces of window glass,
each an inch wide, and 3 inches long, place
them together with two narrow slips of gold
leaf between them, so that the middle piece

of glass has a strip of gold on each of its
sides ; the extremities of the gold slips should
project a little beyond the ends of the glass ;
pass the charge of a large jar through the
gold strips, they will be melted and driven
into the surface of the glass. The outer strips
of glass are usually broken, but that in the
middle frequently remains entire, and is
marked with an indelible metallic stain on
each of its sides where the gold leaf rested.
The prt>s of the universal discharger, de-
scribed in page 65, is very convenient for
holding the slips when performing this ex-
periment.

The colors produced by the explosion of
metals have been applied to impress letters
or ornaments on silk and paper. The outline
of the required figure is first traced on thick
drawing paper, and afterwards cut out in the
manner of stencil plates. The drawing paper
is then heated and placed on the silk or paper
intended to be marked ; n leaf of gold is
then laid upon it, and a card over that ; the
whole is then placed in a press or under a
weight, and a charge from a battery sent
through the gold leaf. The stain is confined
by the interposition of the drawing paper to
the limit of the design, and in this way a
profile, a flower, or any other outline figure
may be very neatly impressed.

360. Wire melted. — Pass a strong shock
through an inch or two of fine watch pen-
dulum wire, and it will be melted. Try this
experiment until you have found the greatest
length of ware that can be melted by a certain
jar, charged to a certain height by the
quadrant electrometer. Then join a second
jar to the first, charge them to the same
height as before, and increase the length of
wire to four times that which was melted
by the single jar, and the whole of this will
in like manner run into drops. If there are
three jars, it will melt 9 inches of wire, and
so on for other numbers.

361. Instead of charging the single jar to
the same intensity as before, use two jirs,
connect them together, and charge them to
half the intensity ; there will be melted the
same length of wire as by the single jar
which was charged to double the height.

The fusion of wire may therefore be em-
ployed as a measure of the quantity of elec-
tricity accumulated on any charged surface ;
for the preceding experiments show that any
given quantity of electricity will fuse the
same length of wire, whether it be disposed
in two jars or one ; and hence it may be
concluded, that the greater or less intensity
of a charge does not materially affect its
wire-melting power. This test is therefore
practically useful, for the various electro-
meters measure only the intensity, and are

76

equally affected by one jar as by a battery
of one hundred. When the fusion of wire
is taken as a test of electrical power, care
should be taken that the length of the circuit
is always the same, and that the degrees of
ignition are uniform ; for a wire maybe melted
with but slight variations of appearance,
when very different quantities of electricity
have been transmitted through it. The lowest j
degree of perfect ignition ought therefore to !
be obtained in all comparative experiments,
and its phenomena should be uniform, that j
is, as soon as the discharge is made, the
wire should become red hot in its whole
length, and then fall into drops. In order
to ensure a perfect uniformity in this respect
throughout a series of experiments, Pro-
fessor Hare has invented the apparatus
shown benealh : — This consists of two bent
arms, which diverge from a centre, as a pair
of compasses, and when adjusted are held
tight by a screw at the centre. A reel of
fine pendulum wire is fixed at one end by a
screw, and at the other by a small pair of
nippers. The whole is of baked wood, with
glass supports.

The melting of metals by electricity may
be considered as a chemical rather than a
mechanical effect, particularly as upon ex-
amination the melted metals are found after-
wards not in a metallic state, so much as in
that of an oxyde. It is not supposed in these
cases that the electric fluid acts otherwise
than by raising the temperature of the metal,
so as to enable it to combine with the oxygen
of the surrounding air ; the same cause will
often reduce an oxyde to a metallic state,
particularly of such metals as are thus re-
duced by heat. Mr. Cuthbertson made many
experiments upon this subject, using for the
performance of them a somewhat extensive
battery, though such is not by any means
necessary for the majority of cases. Besides
the reduction of metallic oxydes, electricity
often occasions still more evident chemical
changes, and although its power in this re-
spect does by no means equal that of gal-
vanism, yet when we are enabled to procure

a powerful stream of the fluid, as in the elec-
tricity of steam afterwards discussed, the
effect of free electricity in producing chemical
and magnetic changes is by no means incon-
siderable. The following experiments will
illustrate a few facts relative to this subject.

362. Prismatic colors produced. — Place
a smooth and flat piece of metal between
the points of the universal discharger, pass
several explosions of a battery through the
wires, and the discharger will gradually form
on the metal different circles, beautifully
tinged with the prismatic colors. The circles
appear rooner, and are closer to each other,
the nearer the point is to the surface of the
metal. The number of rings or circles de-
pend on the sharpness of the points, the
experiment therefore succeeds better if a
sharp needle is fastened to one of the points
of the discharger. This experiment has been
thought to account for the fairy rings, dis-
coverable on downs and meadows, but this
appearance is now thought to be derived
from the growth of a certain species of fun-
gus, whirl) has the peculiar property of v.ot
growing on any spot where it has grown
before ; a single plant then first arises, the
second season others spring up around its
site, the third year still further off, and so
on for a length of time. We do not give the
above as our own opinion, but as one pretty
general among naturalists. These prismatic
electrical cireles are marked most distinctly
upon such metals as melt with the least heat.

363. E^dnciion of vermiUior). — Color a
card wit^h vermillion, mixing it up with water
and a little gum, such as that already pre-
pared in the boxes of water colors, place it
when dry upon the table of the universal
discharger ; the wires being one on each sid t
of the card, at about the distance of 1 inch
from each other. If the charge be now
passed through the wires, the fluid will pass
across the surface of the card to the part over
the negative wire, and it will there perforate
the card in its passage to the negative wire.
The course of the fluid is permanently in-
dicated by a neat black line on the card,
reaching from the point of the positive wire
to the hole, and by a diffused black mark
on the opposite side of the card around the
perforation, and next the negative wire.
These effects are very constant, the black
line always appearing on the side of the card
which is in contact with the positive wire,
and the perforation being near the negative
wire.

364. Draw a line \ an inch broad on a
card with tincture of litmus, take a number
of sparks from a machine along tlie wetted
line, and the litmus will be changed to a red
color ; this arises from the action of the elec-
tric fluid occasioning the formation of nitric

77

?.cid by a chemical union of the nitrogen and
oxygen of the air through which the fluid
passes.

365. Decomposition of iodide of potassium.
— Damp a piece of white paper with the
iodide of potassium ; upon taking a series of
sparks along the card the compound is decom-
posed, the oxygen of the air combines with
the potassium, and suffers the iodine to
escape, as may be known by the peculiar
odour of that substance, and by holding over
the card any article which has just been
starched, and which by the action of the
iodine will become of a bright blue color.

3G6. Reduction of tin. — Introduce some
oxyde of tin into a glass tube, so that when
the tube is laid horizontally, the oxyde may
cover about ^ an inch of its lower internal
surface. Place the tube on the table of the
universal discharger, and introduce the
pointed wires into its opposite ends, that the
portion of oxyde may lay between them.
Pass several strontj shocks in succession
through the tube, replacing the oxyde in its
situation, should it be dispersed. If the
charges are sufficiently powerful, a part or
the tube will soon be stained with metallic
tin, which his been revived by the action or
the transmitted electricity.

367. Reduction of mercury . — Perform the
same experiment with Vermillion in a tube,
the mercury will be separated, and that with
such facility that the charge of a very mo-
derately-sized jar will be fully sufficient.

368. Acid and alkaline effects. — Take a
small glass tube of the shape of the letter V,
each arm of it being about 4 inches. Fill it
to 2 inches in depth with water slightly co-
lored with litmus. Put a cork in each end,
with a very fine pointed wire projecting in-
side the corks, so as just to touch the liquid ;
connect the outer end of one wire with the
prime conductor, and the end of the other
wire with the cushion ; the chain from the
latter, and which usually connects it with the
ground being removed. Upon passing a
stream of electricity through the tinged
water, the positive end will soon appear red,
owing to the formation of nitric acid. If,
when this is the case, the apparatus is re-
versed so that the positive side becomes the
negative, the blue color will be restored,
showing that in free electricity, as well as in
galvanism, the two poles produce acid and
alkaline properties. In this experiment it is
best to have the wires covered with sealing
wax, except at their points.

369. Oil of tartar crystallized. — Take a
glass tube about 4 inches long, a quarter of an
inch in diameter, and open at the both ends;
moisten the inside of the tube with oil ot
tartar per dciiquiem, that is, pearlash which

has liquified by contact with the air. Tlieu
fix two pieces of cork into the ends of the
tube, and pass a wire through each cork, so
that the ends of the wires which are within
the tube may be about three quarters of an
inch asunder. Connect one wire with the
outside coating of a large jar, and form a
a communication from the other to the ball
of the jar, so as to pass the discharge through
the tube ; repeat this several times, and the
oil of tartar will very often give manifest
signs of crystallization. This is supposed to
arise from the formation of nitric acid by
the electrical action upon the air, and this
uniting with the oil of tartar forms nitrate
of potass or saltpetre, the same as in Ex.
364.

370. Decomposition of water. — The power
of electricity in decomposing water was first
discovered in 1 789 by M r, Cuthbertson. The
manner of performing the experiment was
by using a glass tube, a foot long, and -i- of
an inch in diameter, through one end of
which was inserted a gold wire, which pro-
jected an inch and \ into the tube, which,
after its insertion, was hermetically sealed.
The other end of the tube was left open, ex,
cept that a cork loosely covered it; a wire of
the same description passed through this
cork, so that its extremity came to a distance
of about ^5 an inch from the first wire. The
tube was then filled with distilled water,
from which the air had been extracted by
the air pump, and inverted in a vessel con-
taining mercury. A little common air was
let into the top of the tube, in order to pre-
vent its being broken by the discharge.
Electrical shocks were then passed between
the two ends of the wires through the water
in the tube, by means of a Leyden jar which
had a square foot of coated surface. At each
explosion, bubbles of gas rose to the top of
the tube, and when sufficient water had been
displaced to lay bare the wires, the next
shock kindled the gases, and caused their
reunion ; thus decomposition and recomposi-
tion were eflFected by the same agent.

Dr. Wollaston published in the Philoso-
vhical Transactions a description of analysing
water by the transmission of sparks, instead
of shocks. Tiie following is from his paper
on the subject : — " Having procured a small
wire of fine gold, and given to it as fine a
point as I could, I inserted it into a capillary
glass tube, and after heating the tube so as
to make it adhere to the point, and cover it
at every part, I gradually ground it down,
till with a pocket lens 1 could discern that
the point of gold was exposed. The success
of this method exceeded my expectations ; I
coated several wires in the same mannery
and found that when sparks from the con-
ductors before mentioned were made to pass

78

through water, by means of a point so
guarded, a spark passing to the distance of
^ of an inch would decompose water, when
the point exposed did not exceed one seven-
hun<h-edth of an inch in diameter. With
another point which I estimated at one fifteen
thousandths, a succession of sparks one-
twentieth of an inch in length aftbided a
current of small bubbles of air." In these
experiments the gases were liberated at both
poles. Dr. Faraday however has devised a
simple plan for evolving the gases, so that
oxygen shall make its appearance at the one
pole and hydrogen at the other, and also for
other electro -chemical decomposition. The
following is Mr. Faraday's description of his
apparatus. " Upon a glass plate, placed
over, but raised above a piece of white paper,
80 that shadows may not interfere, put two
small slips of tin- foil ; connect one of these
by an insulated wire with a machine, and the
other with the discharging train or negative
conductor. Provide two pieces of fine
platinum wire , bent as in the figure an-
nexed, so that the part D F shall be nearly

Pz/-

upright, while the whole is resting on the j
three bearing points P E F, place them as i
«hown beneath, the points P N become then |
the decomposing poles.''

371. Place a large drop of muriatic acid,
rendered blue by sulphate of indigo, so that
P and N may be immersed in it at opposite
sides ; then send a current of electricity
through it from a good machine, and chlorine
(shown by its bleaching effects) will be
evolved at P.

372. Place a drop of solution of the iodide
of potassium, mixed with starch, between the
poles, and the current will evolve iodine at P.

373. Put a drop of solution of copper
between the poles, and the current will then
cause the precipitation of metallic copper

at N.

374. Moisten a very small slip of litmus
paper in a solution of caustic potash, and
then pass a succession of sparks over its
length in the air, the electricity will by de-
grees neutralize the acid, and consequently
form with it the nitrate of potass or saltpetre,
so that the paper becomes touch paper.

375. The composition of water. — In the
experiments on the electric pistol the noise
and flash of light were occasioned by the
chemical union of the hydrogen, or gas in-
jected into it with the oxygen of the air. Now
chemists are aware that this union produces
water, this is evident, by inspecting the
pistol after it has been several times fired,
when it will be found quite damp with the
moisture so formed.

376. Eudiometers. — The fact of certain
gases being iufiamed by the electric spark

has given rise to various instru-
ments called eudiometers, one
of the most simple of which is
shown in the margin. It con-
sists of a thick glass tube closed
at the upper end, and open
below, where it dips into a cup
or basin of mercury. It is
graduated along the side, and
has two wires through the
upper part which approach
each other. The tube may be
supported in any convenient manner. The
tube is filled with mercury or water, (according
to the kind of gas to be operated upon) ; it
is then reversed, and the gas to be operated
upon suffered to ascend the tube, until a
certain quantity has been introduced. The
electric spark or shock is then j)assed from
the one wire to the other, when the gas is
inflamed. The result is seen by the product
left. In some cases the maximum effect takes
place with the first shock ; with others not
until after some hours' electrization. The
following table shows the result of all these
actions : —

Opera-led upon. Result.

Cwriitiion air and hydrogen. . . . Water and nitrogen.

Oxygen and hydrogen Water.

Chlorine and hydrogen Hydrochloric acid.

Hydrochloric acid and oxygen Chlorine.

Carbonic oxide and oxygen Carbonic acid.

Nitrogen and oxygen Nitric acid.

Sulphurous aciri and oxygen . . Sulphuric acid.

Oxygen and ammonia Water and nitrogen.

Hydrochloric acid Hydrogen.

Fluoric acid Hydrogen,

^,., J Nitric acid and

Nitrous gas j nitrogen.

Sulphuretted hydrogen Sulphur & hydrogen.

Ammonia Hydrogen & nitrogen

Olefiant gas Charcoal fiihydrogen

The communication of magnetism to
needles depends upon a fact which was

79

unknown wlien experiments with that object
were first made ; that is, that the electrical
fluid and fhe magnetic fluid act in directions
opposite to each other. Thus magnetism
induces a magnetized needle to turn north
and south, or in other words, the magnetic
fluids of the earth have a tendency or di-
rection to those points, while the electrical
currents of the earth have a direction east
and west, or round the equator, correspondent
to the apparent motion of the sun in its
course. It is more than probable that the
magnetic currents of the earth are derived
from, or occasioned by the electrical ; at any
rate the science of electro- magnetism shows
us that whenever an electrical current sets in
one direction, any matter which has a ten-
dency to become magnetic will arrange itself
at right angles to the electrical course. In
magnetizing a steel needle by electricity,
therefore to produce a constant effect, it is
necessary to lay the wire which conveys the
fluid across the needle to be magnetized. If
the electrical current crossing it once only
produces a certain effect, crossing it twice
will produce one that is double ; a third
course will be still stronger, always allowing

the fluid to run in the same direction. Now
the only way to make an electric shock pass
several times across a needle without passing
through it, is to twist the wire which conveys
the current into a helix around the needle,
the latter being for the time wrapped in
paper, and the various coils of the helix
being drawn out, so that they shall not touch
each other, as represented in the preceding
cut. That end of the needle nearest to the
inner coating, or that end which is shown in
the cut to be connected with the discharging
rod, will be a north pole.

This method of making a magnet by elec-
tricity is certain, even with a Leyden jar of
a pint size ; whereas, by the old methods
described beneath, the success is at all times
very uncertain, even with a strong battery.
The following are the experiments alluded to.

377. Place a steel wire in the direction
from north to south, and pass a moderately
strong charge of a battery through it ; it will
become magnetic, the end that lies southward
being the south pole.

378. Render a steel wire slightly magnetic,
and place it in the magnetic meridian, with
its south pole towards the north. A strong
charge of a battery will either destroy its
magnetism, or reverse its magnetic poles ; if
its magnetism is merely destroyed, a second
charge will magnetize it anew, but with
reversed poles.

379. Place a steel wire in a perpendicular
position, and pass a strong charge through
it ; it will become magnetic, the upper end
being the south pole. If this end be now
placed downwards, the transmission of ano-
ther charge will destroy its magnetism, or
reverse the poles.

CHAP. X.

THE ELECTROPHORUS AND ELECTRICAL CONFIGURATIONS.

The electrophorus is fully described in page 26. It was once called the perpetual elec-
trical machine, in Consequence of its power of giving off electrical appearances for a long
time after having bt^en once excited, as already explained. In working this simple and
useful instrument, there is a little inconvenience arising from the necessity of touching
the upper plate whenever it is placed upon the lower one ; this may be obviated by pasting
a very narrow slip of tin-foil across the lower resinous plate. As the only object of
touching it is to supply it with fluid from the bottom of the lower plate, it is evident that
a slip of tin foil immediately connected with the lower side will still better answer the

80

purpose than the finger of the operator, which is only connected with the lower aide
by means of his body, the ground, and the table. Why the electric virtue remains in
the electrophorus is easily explained. We will suppose the lower cake to be of resinous
substances. When rubbed then with flannel, it becomes negatively electrified ; when the
upper plate is placed upon it, it will of course by the law of induction induce a contrary
state in the upper plate, and the upper plate will necessarily be electrified plus ; when a
finger touches it, or when it becomes by any other means uninsulated, it will consequently
take a spark from the finger or other connecting body. The finger being removed, and
the plate lifted up, it will remain electrified plus, and consequently be ready to give up
the spark which it had just before taken. Placing it down on the resinous electric a
second time, induction is again occasioned, it will again take a spark, which it will in like
manner give up. Thus the action is continued for a great length of time, the electricity
of the resinous plate being all the time undisturbed, and consequently not diss'pated.
The following experiments are interesting, and differ from all previously recorded.

380. To recover the force of an electro-
l horus. — Place the metallic plate on the
resinous plate, touch it as usual ; then take
it up, and discharge it on the knob of a
Leyden jar ; repeat this operation several
times, this will charge the jar. Now place
the jar on the cake, and move it over its
surface, holding the jar by the knob ; this
will augment the force of the electrophorus,
and by reiterating the operation it will be-
come very powerful.

381. Place a piece of metal on an excited
electrophorus, it may be of any shape ; a pair
of triangular compasses are very convenient
for this purpose. Electrify the piece of metal
with the power which is contrary to that of
the electrophorus, and then remove it by
means of some electric, and afterwards sift
upon the electrophorus some finely powdered
rosin, which will form on its surface curious
radiated figures. When the plate is negative,
and the piece of metal positive, the powder
forms itself principally about those parts
where the metal was placed ; but it the plate
be positive, and the spark negative, the
part where the metal touched will be free
from powder, and the other parts more
covered.

382. Electrical configurations. — Draw
over the surface of a piece of warm glass, or
of a resinous electrophorus, the knob of a
charged Leyden jar. This will of course
charge or electrify it in those places touched
by the knob. Wrap up some powdered rosin
in a piece of muslin, and sift it on the excited
plate. The rosin will cling in a most beau-
tiful radiated manner to those parts which
have been touched by the knob ; a small
distance beyond this will be a mark quite free
from the powder, while over the rest of the
plate, and where no excitation has taken
place, it will merely cover the surface, as it

would any other body not excited. The
reason of this action is as follows : — The
Leyden jar being charged positively, the
streak which it makes upon the plate is ot
course positive also. Rosin, when let fall
from the muslin, is negatively electrified, it
therefore clings to the parts charged posi-
tively. Then again, we have shown that any
body being electrified is surrounded by an
electrical atmosphere, and beyond this it
produces a contrary state of electricity in
any thing adjacent ; thus the rosiu adheres
to the line made by the charged jar, in a
dense mass, beyond this it adheres in streams
or ramifications, because of the positive
electric atmosphere on the two sides. A
little beyond this is a negative atmosphere
arising from induction, here no powder ad-
heres, but rather is driven away, the particles
being negative and repelling each other. Out
of the limit of this clear space no action is
perceptible, and all appearances purely elec-
trical cease. The next experiment shows
this in a still stronger light,

383. Configuration by red lead and sul-
vhur. — Mix together equal parts of powdered
red lead and sulphur, put them in a small
sieve or a piece of muslin. Sift these pow-
ders on a piece of warm glass which has
been drawn over or touched with the knob
of a charged Leyden jar. The powders how-
ever intimately mixed will separate from
each other, because by the sifting one of
them becomes negatively electrified, the other
positively. In falling, therefore, each will
be attracted by such part of the glass as is
in a contrary state to itself, and form distinct
lines and marks on the glass of the most ex-
traordinary and beautiful appearance. The
red lead being electrified positively by- the
sifting, adheres to the outsirie lines in little
stars or dots, which as the electricity of tho

81

sulphur is strongly negative, it adheres to the
central space, where it appears as a line of
small specks or stars, the property of a ne-
gative action ; while the red lead is in brushes
or ramifications, showing its positive condi-
tion. These beautiful figures may be pre-
served for years if made on a sheet of glass
which has a frame to it like a picture, the
glass being after the experiment reversed
towards the back, so that it may not be rubbed
off by accident. A piece of black paper behind
it heightens the effect greatly when to be
preserved. If too much powder be sifted on
it, the surplus may be blown off without
injury. The next cut will give some idea,
although a very inadequate one, of this
beautiful and curious experiment.

384. Projection of chalk. — Suspend the
lower plate of the electrophorus against the
wall, that in this and the following experi-
ments the grosser part of the powder may
fall to the ground, and no more adhere to
the plate than is attracted there by the elec-
tricity diffused thereon. Let a small jar be
charged very weakly, draw its knob over the
resinous plate, and then taking a clothes
brush in one hand, and a piece of chalk in
the other, rub the chalk upon the brush near
to the surface of the plate ; this produces a
plain white line without any ramifications.
When the charge is stronger, the ramifica-
tions are proportionably extended, resem-
bling so many beautiful white feathers.

385. Place a circular brass plate with an
insulating handle upon the resinous plate,
and communicate a spark from the charged
jar to the brass plate. Take this off by its
insulating handle, and project chalk upon the
lower plate. This produces a very regular
circle of ramifications about 4 inches long,
proceeding from the circumference of the
space covered by the brass plate, and within
the circle are a number of irregular figures
somewhat like stars. A shock made to pass
through the same plate generally produces
more distinct ramifications, and sometimes

without any stars within the circle ; at other
times with a quantity of minute specks.

S86. In performing an experiment similar
to the last, let the brass plate be drawn along
towards the edge of the electrophorus whilst
touched with the knob of a jar ; a very beau-
tiful figure will be produced at the projection
of the powder.

387. Draw over the plate a jar strongly
and negatively charged, and afterwards a
pointed wire, held in the hand only, is to be
drawn over the same figure. When chalk is
projected, a beautiful ramified figure is pro-
duced in the middle of the negative one.

388. A conical tin funnel is to be placed
with its base on the middle of the resinous
plate, and a negative strong charge given by
connecting the discharging rod with the
under side of the plate ; then a positive
charge is to be given in the same manner.
Let the funnel be thrown off, and the chalk
projected. Beautiful ramifications are now
produced both within and without the circle.

389. A knob of wood, about an inch in
diameter, is to be placed upon the wire of a
jar which is charged highly positive, and the
knob drawn over the plate so as to touch the
surface. This produces a beautiful figure,
the middle of which is smoothly covt red with
chalk, and the sides finely ramified with
shades.

390. Let the flame of a small wax taper
be at about an inch distance from the middle
of the resinous plate ; then let the knob of a
positively-charged jar be suddenly brought to
the flame, and both the jar and flame be in-
stantly taken away again. In this experi-
ment when the chalk is projected, a circular
space, about 4 inches in diameter, will be clean
and free from powder ; the rest of the plate
uncovered, except by a great number of small
circular or elliptical spots, which shows that
the electrical fluid passed to the plate in de-
tached balls, like some atmospheric meteors.

82

CHAP. XL

ATMOSPHERIC ELECTRICITY, &c.

Many atmospheric phenomena have a resemblance to what we may suppose to be
occasioned by a great accumulation of the electric fluid. It is therefore not surprising
that the earlier electricians acknowledged the similarity of many of those natural pheno-
mena with the experiments which their comparatively small machines enabled them to
perform. The very appearance of lightning induced philosophers long to believe that it
was only a grander species of electricity, excited without the intervention of human art ;
but the proof that they should be actually the same fluid, and should arise from the same
cause, and be subject to the same laws, was reserved for the comprehensive and active
mind of Dr. Franklin. He made the bold assertion, and with a kite made of a silk hand-
kerchief, brought lightning from the clouds, and proved his assertion by performing with
it all the experiments then known.

Ex. 391. Electric kite. — A kite properly
adapted for the purpose of atmospheric
electricity may be made and managed as
follows : — Tie together in the form of a cross
two canes, or still better two thin rods of
deal, about 3 feet long each. To the four
corners of the cross-sticks fasten the corners
of a large silk handkerchief ; a loop must be
made by piercing a hole in two parts of the
handkerchief, and a string fastened to one of
the sticks, in the manner of the loop of a
boy's kite ; indeed a common kite will an-
swer the purpose quite as well as one of silk,
except that if it is to be used in stormy
weather, the latter will by wet soon become
spoiled. The size also is of very little con-
sequence, except that the larger the kite the
higher it will usually ascend, and therefore
for this cause, and this alone, a large kite is
most effective. The kite itself being formed,
and having a common kite tail attached to
it, or else long strips of calico sewed toge-
ther, which will be found more convenient ;
it must be furnished with two or three pointed
thin copper wires fastened to the loop, ex-
tending upwards a few inches above that part
of the kite which flies highest, and projecting
from each other as seen in the figure.

The string is the next object of importance,
that evidently is the best which has a fine
wire or two passing down it. Most persons
desiring this string have taken the trouble to
wind the wire around the whole length of
string previously bought, not knowing that
were they to take the fine wire to any string
spinner, he would weave it up along with the
hemp at once, putting a wire into each strand,
if required, and at the expense of a mere trifle
additional. Supposing a person should be in
such circumstances or situation that this
string cannot very easily be procured, the
best substitute for the wire will be found in
soaking a common string in salt and water
for an hour or two previously to using it. It
will thus imbibe sufficient moisture to render
it a good conductor, even in a very dry at-
mosphere, where string wetted with water
only would become useless. The upper part
of the string must be carefully connected
with the pointed wire carried above the loop.

The lightning, or electric fluid, being thus
attracted at the kite, and led downwards by
the string, it must be retained from passing
silently to the earth beneath. For this pur-
pose it will be necessary that the lower end
of the string be attached to a cord of silk,
about 3 feet long, to be kept quite dry, and
for convenience of operating, a large key is
usually tied at that part where the string and
silk are united. The kite being raised, the
electric fluid will pass down to the key, here
being stopped by the silk cord, it will be
given off* in sparks or flashes, more or less
powerful, in accordance with the quantity of
lightning which may be in the air. The
operator may easily conduct it elsewhere, or

83

charge his conductors or batteries without
difficulty.

No philosophical instrument is more sim-
ple in form and easy to construct than the
electric kite, yet no one needs more care in
its management. To fly it when a thunder
storm is approaching would be attended with
the greatest danger, unless every precaution
be taken. In this state of the atmosphere
the raising and lowering of the kite requires
the utmost circumspection ; to let the string
wind out immediately from a ball in the hand,
making thereby the body a part of the con-
ductor is too venturesome ; the string should
pass over and touch an iron railing, or
through a ring fastened to a metal rod driven
deeply into the ground, whilst the person
who holds it is placed upon a dry glass-legged
stool, or otherwise insulated ; as for example,
upon a pile of books, or paper. When up a
sufficient height, the remainder of the string
may be fastened to the key, and the operator
is then able to remove himself to a safe dis-
tance. It is advisable also that the electric
fluid should never be introduced into a dwel-
ling house, for a thunder storm is a terrific
agent to tamper with, and once invited into i
our houses, may occasion dreadful damage,
ere it be allayed. We have seen flashes o.
4 or 5 feet in length, and once when we left
our kite up during a stormy night, the key
appended to it seemed as it were a ball o»
fire, illuminating all around, and the very
kite and string appeared as if enveloped in
lambent flames. Fortunately, to operate in
weather like this is not necessary. The
calmest and brightest evenings of summer ;
the densest fogs of autumn ; and the clearest
frosts of winter, yield mostly as much fluid
as is convenient to use ; in either time small
sparks will be visible, and may be felt by a
knuckle presented to them, when they will
be found very different from those usually
afforded by the electrical machine. The air
will be found positively electrified ninety-
nine times out of each hundred, yet the
sparks as given by the kite string will be
red, comparatively short, make but little
noise, and be felt so much more pungent
when passing to the hand, that they rather
resemble the vibration, or small shock, than
that known as the electric spark.

392, The proof afl'orded by numerous expe-
riments with the electric kite, that the air was
at all times charged with electricity, and also
that the degree of disturbance and character
of the fluid varied at different times, rendered
philosophers anxious to construct some sim-
ple apparatus which should enable them to
do this without the trouble, delay and danger
of the kite. They therefore turned their
attention to construct more simple instru-
ments, some of which were to be used as a
permanent apparatus, others for temporary

purposes only. As these instruments varied
from each other only in a small degree, and
were all dependant upon the same principle,
we shall describe but two of them. The'first
is called from its inventor and use, Cavallo's
atmospheric electrometer. It is represented
beneath, and consists merely of a common
jointed fishing rod, without the last or smallest
joint. From the extremity of this rod pro-
jects a slender glass tube covered with sealing
wax, and having a cork at its end, from
which a pith ball electrometer is suspended.
There is a small string also which runs the
whole length of the apparatus, to render the
electrometer insulated when required to be
so. It is fastened by a pin to the cork ball
at the top, so that by pulling the string, it is
separated from the cork, and leaves the pith
balls suspended from the waxed glass rod ;
when used, the rod is thrust out of a window,
the string is then pulled ; when the pith balls
diverge, they are then pulled in and examined.

393. Cavallo's rain electrometer.— This
nistrument differs from the former in many
respects ; it is represented beneath. A is a
strong glass tube, about 2 feet and a -^ long,
having a tin fanncl cementod to its extremity,
which funnel defends part of the tube from
the rain. The outside surface of the tube is
wholly covered with sealing wax. C is a
piece of cane, round which brass wires are
twisted in different directions, so as to catch
the rain easily, and at the same time to make
no resistance to the wind. The cane is fixed
into tho tube, and a piece of wire proceedinf

84

from it goes through the tube, and is ter-
minated by a ring, upon which a pair of pith
balls are suspended. This instrument is at-
tached to the side of a window frame, with
the funnel projecting outwards, while the
pith balls are preserved dry within.

Franklin also contrived one or two electric
instruments of the like nature to Cavallo's at-
mospheric electrometer, the object of which
was principally to indicate to him when a
thunder storm was approaching. The whole
of this apparatus is very simple, consisting
merely of a long pointed rod, which proceeded
through a glass tube, that was let into the
roof of the house. The rod bore at the lower
end a clapper, suspended on silk, while there
was a lateral communication by means of a
wire with an insulated bell. When therefore
the fluid was in any considerable abundance,
the bell became charged, it therefore attracted
the clapper, which being then repelled, dis-
charged itself by striking against the other
bell. Thus ringing was kept up.

M. Bichman examining an apparatus of
this kind too nearly, was struck by the light-
ning which descended, and fell a sacrifice to
his too ardent and incautious love of science.

This last apparatus it is evident will only
act when the fluid is in some abundance,
and is not adapted to measure or indicate
those minor indications which belong to calm
weather, while Mr.Cavallo's instruments were
more troublesome than they need have been.
To obviate these inconveniences, M. Saus-
Bure contrived the following more simple and
effective instrument : —

Saussure's atmospheric electrometer con-
sists of a glass case or bottle, with a metal
foot, and four pieces of tin-foil up the sides
in connexion with the bottom. Withinside
the glass are two very fine silver wires,
swinging freely in a loop above, and ending
below in two small pith balls. The upper
part of the instrument, is a brass cap, to
defend the bottle from the wet, terminated
by a ball and a rod of 3 or 4 feet in length,
made in joints, and pointed. (The uj)per

wire is left out in the cut) In fine weather
the hood or cover is taken off. When stand-
ing out of doors, the pith balls diverge, as
soon as fluid is attracted by the point of the
rod

The above remarks and experiments show
not merely that electricity exists in the at-
mosphere, but that it is sometimes at least
in an accumulated form, or similar to that in
which we witness it in the charged Leyden
jar. Thoughts then will arise as to how it
gets into the atmosphere, and this being
accounted for we may be at a loss to find any
analogy between the atmosphere, and a Ley-
den jar, and therefore we may not see clearly
how the air can become charged so as to
receive and deliver up a charge of fluid in so
distinct a manner as in » flash of lightning.
These doubts we will endeavour to remove.
First. Its presence in the atmosphere may
easily be imagined from the experiments
with the gold leaf electrometer in page 9,
and still more so from the electricity of eva-
poration in page 22 ; indeed, evaporation
alone is amply sufficient to account for all
the effects which take place. Although the
evaporation of a few drops of water manifest
but a small effect, yet the whole amount of
the fluid thus disturbed may be imagined, by
stating that 5280 millions of tuns of water,
are, as is imagined, evaporated from the
Mediterranean Sea alone in one summer's
day. It must be observed also that other
causes are always in action, as currents
of wind impinging upon the earth's surface,
the motions of all bodies, chemical change,
&c., sometimes adding to this accumulation,
sometimes decreasing it ; and thus it is that
different parts of the air are differently elec-
trified at the same time.

The next question to clear up is the man-
ner in which the atmosphere becomes charged
to the degree, and in the manner of a Leyden
jar. This also may be illustrated by direct
experiments, which will not merely show the
fact that it does become so charged, but also

85

how other electric atmospheric phenomena
take place, and to what cause may be ascribed
man]/ of the phenomena which are observed
in the course of common electrical experi-
ments. It may be more fully proved as
follows : —

394. Cover two large boards with tin-foil,
suspend one by silken strings from the ceil-
ing, and then connect it with the conductor.
Place the other board parallel to the former, on
an insulating stand that may be easily raised
or lowered to regulate the distance of the plates
from each other. Or place the boards in a
vertical situation parallel to each other, on
insulating stands of the same height. In
most cases this form will be found more con-
venient. These boards may be considered
as the coating to the plate of air which is be-
tween them. Connect one of the boards with
the prime conductor, and the other with the
ground ; turn the cylinder, and that one which
has been united to the prime conductor will
be electrified positively, while the other will
be negative. The space of air between the
two plates acts as a plate of glass, it separates
and keeps asunder the two electric powers.
Touch the negative plate with one hand, and the
positive plate with the other, and a shock will
be received similar to that from a Leyden jar.

395. Place half a ball or any other emi-
nence on the lower plate, supposing them to
be horizontal. The spark in this case will
strike the eminence, and the plate of air be
discharged. The experiments with these
boards will be more pleasing if one surface
of the upper board is covered with gilt lea-
ther. The two plates when charged are
supposed to represent the state of the earth
and clouds during a thunder storm ; the
clouds being in one state, and the earth in
another. — Adams.

396. Pillars of sand and whirlwind imi-
tated.— Place bran or small pieces of paper
in the middle of the lower board. When the
machine is put in action, these will be alter-
nately attracted and repelled with great ra-
pidity, and agitated in an amazing manner.
This experiment is very similar to that of the
dancing figures, Ea\ 136, but owing to the
very much greater size of the boards, and
the lightness of the objects, a very curious
phenomenon is generally observed, namely,
that each particle of bran turns on its axis
at the time it is moving up and down ; and
if the electricity be strong, the whole unite
into a column which turns on its axis, and
often rolls along until it arrives at the edge
of the board, where it flies off. This ex-
periment is an exact imitation of a whirlwind,
and also of the rolling pillars of sand -which
are so much a terror to the African traveller.

397. Imitative earthquake. — Place a build-

ing, which is formed of several loose pieces
of wood, on a wet board in the middle of a
large basin of water ; let the electric flash from
a battery be made to pass over the board, or
over the water, or over both, the water Mill
be strongly agitated, and the building thrown
down.

398. If a long narrow trough of water be
made part of the circuit in the discharge of
a battery, and a person's hands be immersed
in the water at the time of the explosion, he
will feel an odd vibration in the water, very
different from an electrical shock. The quick*
stroke from the repercussion of the air and
the vapor is communicated to the hand by
the water, and the hand receives a shock
similar to that received by a ship at sea
during an earthquake.

399. Glaciers imitated. — The cause of the
irregularity on the surface of glaciers has been
much discussed of late years, and among
other theories it has been supposed to have
arisen from the passage of strong currents
of electricity over them. This theory is
somewhat supported by passing a strong
shock over the surface of a sheet of ice,
which becomes impitted with numerous ca-
vities and irregularities, similar to, but of
course on a much smaller scale than in
nature.

400. Aurora Borealis. — This is ad-
mittedly electrical, and is so easily and
exactly imitated as to leave no doubt of the
fact. We will refer to the experiments in
Vacuo, described in page 51, where this
phenomenon is explained : and the identity
becomes the more evident from the circum-
stances that whenever it appears, the atmo-
sphere is found replete with the electric
fluid ; and, secondly, because it equally with
electricity affects the magnetic needle. It
puts on appearances different from lightning
because it occurs at a considerable elevation
above the earth, where, as before explained,
the air is much rarefied.

401. Falling stars. — Whenever the electric
fluid is at a more moderate height, and in a
more concentrated form, it occasions those
electrical appearances, known to us as falling-
stars or n-.eteors ; these are generally consi-
dered indicative of rain, and not without
some cause, inasmuch as rain, hail, snow,
&c. are always produced by any sudden
electrical change that takes place.

They may be imitated by passing a shock
through a long exhausted tube, similarly
constructed to that described and figured as
the Aurora flash, page 51, but not exceeding
^ an inch in diameter.

402. Rain, sAow, $fc. — It has been said
by some that the reason rain, &c. falls in

86

drops, and still more so, why snow appears
in light fleecy flakes is owing to electrical
repulsion, as is somewhat proved by the ex-
periment of the expansion of a fleecy feather
when driven off by an excited tube, and also
by the spun sealing-wax.

403. Fiery rain. — Thus also can we in
some degree explain the fiery rain mentioned
in the Scriptures, and by various ancient
writers, certain it is that every drop of rain
which falls during a thunder-storm is charged
with the fluid, and therefore contributes to
divest the storm of its fury.

404. Waterspout. — The waterspout, that
wonderful and terrific object, is too easily
explained by electric attraction to leave any
doubt that its cause is a highly -charged state
of the air, and we are confirmed in this con-
clusion by the means taken to disperse it,
namely, by firing cannon and pointing sharp
weapons at it. Ex. 154 and 155, showeff"ects
very analogous to the waterspout. The fol-
lowing cut gives the usual appearance of this

terrific phenomenon ; the sea beneath it is
agitated, and rises up in a short column ;
the cloud above stretches downwards in the
formof a funnel, sometimes remaining steady,
but more frequently moving forwards, and
involving in destructive torrents of water
every thing it touches ; and so great is often
its power, as to draw up fish and other ob-
-jects : hence the frequent accounts we read
of showers of frogs ^ fish, S(c.

IDENTITY WITH LIGHTNING.

The identity of the electric fluid with light-
ningwasone of the first-established facts rela-
tive to atmospheric electricity, and as it was
the first in time, so it is also in importance to
us, teaching not merely the origin and proper-
ties of that mighty power of nature, but also
how to escape from its direful effects. The very
appearance of lightning would induce us to at-
tribute it to electricity, nor is this supposi-
tion in any way weakened by our experimental
researches. If we compare the properties of
electricity with those ot lightning, we shall
find them closely analogous, or rather
identical.

405. Lightning destroys animal and ve<, e-
table life, so does electricity. — Procure a
mouse, and send a strong shock through his
body from head to tail, and the poor animal
will instantly fall dead. To pass the shock
through the head or chest seldom kills, but
if it pass along the spinal marrow it always
does, the tail should therefore always form
part of the circuit.

406. When the animal is dead, pass a
second shock in the same manner as that
which killed it, and the fluid instead of pass-
ing through the animal will pass over it, and
consequently be luminous. This is a curious
experiment, as it shows that the substance of
the animal ceases to be a good conductor
with its life. It is a well-known physiological
fact, that in the bodies of persons killed by
lightning, as well as of animals killed by an
electrical shock, the blood does not coagu-
late, but very soon becomes putrid, and the
flesh black. Lightning passing over the skin
of a person scorches it in the same manner
as an ordinary flame would do, and the after
sensation is very similar.

407. Pass a very small shock through a
flounder, or other fish, and it will be deprived
cf life instantly.

408. Put several fish into a basin of water,
and send a shock through the water, the fish
will be killed in a moment.

409. Pass a strong shock from the top to
the root of a balsam or geranium plant, and
although no immediate eff'ect will be apparent,
yet the plant will be eff"ectuaUy killed, as
will be evident after a few days.

The efi'ect of lightning in destroying va-
rious things opposed to its passage, in setting
fire to combustible substances, rending trees
and disturbing the magnet, we have shown
in the chapter on the mechanical and other
effects of electricity to be easily occasioned
by the rapid progress of the fluid through
them. Their identity therefore is clearly
established, and the importance of electricity
as well as its universal agency, becomes more
conspicuous as we advance. Our preservation
from lightning is evidently of the first im-
portance, and the manner best to accomplish
this was first suggested by Dr. Franklin.
Soon after his important discovery of the
true nature of the electric fluid, he pointed
out the utility of conductors to buildings.
The necessity of these was admitted by all,
but philosophers could not agree among
themselves as to these conductors, whether
they should be terminated by a point or a
ball. Those who contended for the superior
efficacy of a ball, maintained that a point
drew the fluid from a greater distance than
a ball, and therefore the cloud was as it were
invited towards the building. As many

87

experiments were brought forward in fur-
therance of these arguments, it had many
supporters, till Franklin, by his ingenious
explanation of their experiments, and one of
his own, set the matter for ever at rest. The
following experiments are those now alluded
to:—

410. Fasten the head of hair of Ea;. 129,
or the glass feather of Ex. 128, to the prime
conductor, and turn the machine, while the
hair or the filaments of the feather are di-
vergent, hold towards them a ball; the fila-
ments will immediately be attracted, and will
cling round the ball ; but hold a point instead
of the ball, and they will be repelled.

411. Franklin's cloud. — Fasten three loose
pieces of cotton wool upon a linen thread,
so that they shall hang at about 2 inches dis-
tance from each other, or else fasten three
fleecy feathers in the same way. Adjust this
apparatus to the prime conductor, turn the
machine, and hold a ball and point alter-
nately to the outermost feather. When the
ball is held, the feathers will clasp the ball,
but when the point approaches, the first
feather recedes to the second, the second to
the third, and the third to the conductor.

These experiments apparently prove that
the fluid is more attracted by the ball than
the point, but this conclusion is erroneous ;
the reason of the recession of the feathers in
the last experiment is not because they are
repelled by the point, but because the point
rapidly deprives the outermost feather of its
fluid, and then that feather being in a neutral
state retires, or is attracted to the next.
The point acts in like manner upon this,
which occasions them both to retire and so
on. Thus it is with a pointed lightning con-
ductor, it draws off the fluid from a thunder
cloud so rapidly as to take away the cause of
danger. It is however to be tested, whether
in neutralizing the cloud it does not endanger
the building ; this is not so, provided the
conductor is perfect, and offers a continuous
metallic course from the fluid to the ground,
its ultimate destination. If the conductor be
inadequate, it will be melted, if it be inter-
rupted, although it be pointed, yet a shock
will as readily pass along it as if it were
terminated by a ball, and as we have seen
from experiments in a former chapter a
concussion and consequent injury must al-
ways take place when this is the case. The
following apparatus are peculiarly adapted
to show the truth of this position : —

412. Thunder house. — This ingenious ar-
ticle is made of an upright piece of baked
mahogany, formed like the gable of a house,
as B B, and placed upon a wooden stand. A
wire marked C runs downwards throughout
its whole length. It is terminated above by
a ball A, which being unscrewed shows a

point beneath it. In one or two parts of the

gable are square pieces of wood cut out.
A These are ^ of an inch
thick, and 1 inch square
on the side. They are
shown at D and F ; are
made so as to fit loosely
into a hole cut partly
into the gable to receive
them, and have a wire
running across each, so
placed, that putting in
the pieces in one way,
the wires shall with C E
_ form a continuous and
^uninterrupted line, and
when put crosswise,

there shall be a want of contiguity at that

place, as shown at D.

413. Pass a shock from A to E, while the
ball remains on and the wire is continuous,
and it will make a loud report, without dis-
turbing either piece of wood.

414. Pass a shock, or rather endeavour to
do so, with the upper ball taken off", so that
the point is displayed. The fluid will pass
and discharge the jar, but not in the manner
of the shock, and no report will be heard.

415. Now place either of the pieces of
wood crosswise, and restore the ball to the
top. The shock will pass and throw out tae
piece of wood that was placed crosswise,
but not disturb the other piece.

416. Let the piece of wood be placed
crosswise, as in the last experiment, but re-
move the ball. Upon discharging the Ley den
^"ar, a real shock will pass, and the wood will
be displaced, although a point terminates
the apparatus.

417. Electrical pyramid. — This is an
apparatus of the same nature as the last,

and is to be used in the
same manner. A is a four-
sided pyramidal piece of
wood, or more usually con-
sists of four pieces fitting
on to each other. A line
runs down the whole in
front, and is moreover con-
tinued down the base B ;
continuity being occasioned
by a small square, as in
the thunder house. This
is marked D in the cut,
and is seen with its wire
placed sideways. Upon
this moveable square, and
upon the back of the base,
the upper portion is supported by three
balls. When a shock is sent from E to F,
the square D is thrown out, and the upper
part of the pyramid falls.

88

Tlius it is proved, that lightning conductors
should be sufficiently large, lest they should
be melted, and continuous lest they should
give a shock rather than draw off the fluid
silently and harmlessly. Also we learn from
JBx. 197, and following, that the point with
which they are terminated above should pro-
ject for some height above the highest parts ot
the building. Thus it is that chimnies are so
often injured, but not from this cause alone ;
they being lined with soot, which is a good
conductor, induces the flash to take that
course. Therefore during a thunder storm
it is dangerous to get near a lofty tree or a
prominent chimney, so on a plain ; even a
sheaf of corn is sufficient to direct the course
of the lightning, inasmuch as straw is a good
conductor, though not so good as the human
body ; thus life would be endangered, for the
fluid always takes the best conductor.

Strange as it may appear, yet it is a fact, that

many persons are killed without any electric
matter passiug through them at all, and thus
we are not wholly safe even when the storm is
wasting its fury upon other objects. This is
easily accounted for by electrical induction,
as follows : — When a charged cloud passes
over a man, it affects all the fluid in his body,
for as the fluid repels itself, the natural
quantity he possesses is driven to his feet,
which therefore become electrified positively,
or have more than their natural share, while
his head becomes negative. As soon as the
overhanging cloud is discharged by striking
a tree, rock or other object, the equihbrium
of his body is immediately restored, and that
with such impetuosity that convulsion or
death is the consequence. Birds roosting in
trees are thus often killed, or in cases where
death does not ensue, blindness is the fre-
quent result.

CHAP. XII.

MEDICAL AND ANIMAL ELECTRICITY.

This part of the subject, although of importance in a physiological point of view, yet
scarcely is entitled to a place here, because of its yielding few or no experiments ; a short
account however of administering electricity medically may be advantageously admitted ;
and we would premise the account by stating, that electricity should always be ad-
ministered gently at first, and its power only increased when the gentle application is
found ineff'ectual, except in cases of paralysis, or when used to remove obstructions ;
its full power may be at once administered ; but even here the shock of a quart Leyden jar
should never be exceeded ; the frequency of the shocks, and not the strength of them being
most to be relied upon. Also we would remark that no danger to life can arise from the
administration of electricity in any way, unless, as before observed, it be sent along the
spine, or perhaps through the brain. We have been more than once thrown down by the
power of the shock, but even by the passage of a large battery through the arms have felt
no ill effects, unless perhaps a slight head-ache. Strong shocks are however extremely
unpleasant, and we trust that our experimental friends will not operate with any but a
small jar, at all times, unless a large number of persons are to receive the charge, and
even then to be very careful to exclude young children and delicate persons, as the fear
alone may occasion distressing effects.

Electricity, according to the mode of its administration. Is either sedative, stimulant,
or deobstruent ; hence the propriety of its application to diseases of quite contrary cha-
racter. We have applied it to palsies, rheumatisms, inflammations, contractions of the
muscles, amaurosis, chilblains, tumours, sprains, and other diseases and accidents. The
methods of electrifying are five ; first, simple electrization, or merely subjecting the person
to the action of electricity, by placing him on a glass-legged stool, and connecting him with
the electrical machine when in use. Second, drawing the fluid from the particular part of
his body which may be aftected ; this is either done holding towards h«m a wooden point.

89

when a cooling and refreshing breeze is perceptible, or by placing your hand upon his
clothing, when if any woollen or silk interpose between your hand and his body he will feel
a peculiar pricking sensation, occasioned by innumerable sparks issuing from the part
beneath the hand, and which will soon occasion a great degree of warmth in that part. Or
a third method is to draw the fluid from him by means of sparks, taken by the knuckle, or
else by a wire with a metallic ball at the end of it. If the operator hold this tight he
will not feel the sparks himself. A stronger way of drawing off electricity is by means
of what are called vibrations, and a still stronger, sparks. For these two last the patient
either stands, or sits on an ordinary chair, and not on the glass stool before mentioned.

The following apparatus is all that is essentially necessary, though many other articles
have been described and recommended. The first essential is a glass-legged stool; if

required for cheapness it may be a piece of
board, made smooth, and with round edges,
supported upon four wine bottles, pegs being
driven into the under-side of the board to fit
the necks of the bottles ; solid glass legs are,
however, infinitely better. In using the stool,
a large sheet of brown paper or pasteboard ;
or, still better, a piece of oil-cloth, larger
than the stool itself, is to be placed beneath it on the floor, to prevent the filaments of the
carpet, or the dust of the floor, from drawing away any of the fluid accumulated.

The next requisite is a flexible tube or connector ; as a chain must necessarily have
n any edges or points, the stool should be connected to the machine by a chain which
is sewed up in silk, and afterwards varnished or covered with India rubber; thus there
vill be no loss of fluid. But for numerous purposes the instrument called a flexible tube
is much better. This is explained in page 63.

A wooden or metal point is sometimes used ; by this a gentle stream of electricity, is
given to or taken from a patient, according as the point is held in the hand of the operator,
(ihe patient being on the electrical stool,) or attached to the glass-handled flexible tube,
tie patient being on the ground, or rather not insulated. These simple instruments^
with the exception of a wire with a brass ball at the end of it, are all that are necessary
fcr the administration of the electric fluid, except when shocks are to be given. In
tlis case a Leyden jar is indispensable. Any Leyden jar may be used, but the one
shown, and described beneath, is most convenient for medical purposes.

Medical Jar. — This is like an ordinary Leyden jar, covered and lined to a certain height
with tin-foil, as at B. A wooden cap is then prepared for it, and a hole just admitting a glass
tube A, is bored in the middle of the cap. The tube reaches below to within 2 inches of the
bottom, and projects upwards above the cap, about 3 inches.
This tube is also partly lined and covered with tin-foil, so
placed that rather more than an inch of the glass is left
uncovered at the lower end, and about 2 inches at the upper
end. The tube is cemented to the top of the bottle, and a
smaller cap cemented on the top of the glass tube ; but
before this last is cemented on, three hooks are drilled in
it ; one for a hook wherewith to suspend the phial from the
conductor, the two others are to be left open ; one of them
to admit a wire to touch the inner coating of the tube, the
other a second wire, sufficienl«ly long to reach to the coating
of the phial — these are shown in the cut at C and D. A
wire is also tv\isted round the outer coating of the inner
tube, which projects outwards sufficiently to touch the inner
coating of the phial. On the outer coating of the phial is
fastened a hook, marked F, for the convenience of attaching
a chain. This bottle is always used in connexion with' the
medical electrometer, described in page 56 ; and also with a pair of directors, glass-
handled instruments, shown in the margin.

These directors are for two purposes, first, that by means of their balls they shall be
able to direct the fluid or shock to any particular part only, and confine it thereto ; and
secondly, that the operator, holding the glass handles, may not participate in the shock,
which passes in a straight line from the ball of the one director to the ball of the other, when
they are respectively connected by chains, the one to the outside of the medical bottle,
the other to the sliding piece of the electrometer. When both wires are in the bottle, the

44

90

the whole bottle is chargea, and the strength of the shock is considerable; but when the
longer wire is drawn out, the only one left will be that which tuuches the inner coating of
the tube, and this tube being so small, the shocks which will pass will be less energetic than
those given by the larger bottle, and will altogether have a different character. They are,
indeed, intermediate in effect between sparks and shocks, and are called vibrations.

Animal electricity partakes more of the nature of galvanism than that free state of
frictional electricity, which is our present subject. The power of giving shocks appears
wholly confined to fish ; no species of any other race of animals, havhig any power analogous
to the complicated apparatus found for this purpose, applied to the electrical eel and the
torpedo. Several of the former of these fishes have of late years been brought to this country,
and experimented with. The shock is indeed sudden and momentary, like that from a
Leyden battery, but the effects when a continual current is produced by connecting the
head and tail of the animal in decomposing water, forming and disturbing a magnet,
giving a faint spark only, even under the most favorable circumstances, and giving the
shock only when the circuit is wholly formed of good conductors, (requiring even the
hands to be wetted,) and the whole of its electrical power taking its origin among wet,
fleshy, and dissimilar animal substances, show the propriety of excluding an account of the
animals, interesting as is their nature and wonderful their powers.

CHAP. XIII.

HYDRO-ELECTRICITY, OR ELECTRICITY OF WATER.

The fact that the issuing of steam through an orifice should give rise to electrical ap-
pearances was not merely unknown, but not even suspected, until little more than three
years since, when an account appeared in the Philosophical Magazine, that the boiler of a
steam engine near Newcastle being defective, (the joint or fiaunch of the safety valve having
given way, so that the steam, which was at a pressure of 35 lbs. per square inch, was issuing
forcibly through the aperture,) a Mr. Patterson, who was standing near, upon touching
the weiglit of tlie safety valve, felt a pricking sensation in the fingers. A few days after-
wards the same being repeated, induced a greater attention to the subject, when a spark
was elicited ; and proper apparatus being procured, a shock, and other electrical phenomena.
Thus this wonderful discovery was made, and as it may well be imagined soon bruited
abroad, drawing the attention of philosophers to the subject ; particularly the indefati-
gable and erudite chemist and electrician. Professor Faraday, who has lately read a paper
to the Royal Society, entitled, " On the Electricity evolved by the Friction of Water and
Steam against other Bodies." The object of the experiments detailed in this paper is to
trace the source of the electricity which accompanies the issue of the steam. Professoi
Faraday relates that electricity is never excited by the passage of pure steam, but only
v;hen water is also present ; hence he concludes that it is altogether the effect of the friction
of globules of water against the sides of the opening, urged forward by the rapid passage
of the steam. The effect of this is to render the steam or water positive, and the pipes
from which it issues negative. Heat, by preventing the condensation of steam into water,
likewise prevents the evolution of electricity, which again speedily appears by cooling the
passages, so as to restore the water which is necessary for producing the efftct. Water
will not excite electricity unless it be pure ; the addition to it of any soluble salt or acid,
even in minute quantity, is sufficient to destroy this property. The addition of oil of
turpentine, on the other hand, occasions the development of electricity of an opposite kind
to that which is excited by water. A similar and more permanent eff"ect is produced by
the introduction of olive oil along with the water. Similar results were obtained when n
stream of compressed air was substituted by steam.

These experiments and conclusions of Professor Faraday are interesting, and the more
so, as by them we are able to show by fact what we could before these discoveries only
infer, namely, the mighty power called into action by the currents of air, vapor and mois-
ture of the atmosphere ; indeed, it is evident, that a gun cannot be discharged, not even
an air gun, nor yet a comrnou tea kettle give suam irom its spout, without exciting the
electric fluid, nor is it in small quantities either, as the following account of the largest and
most powerful electrical machine ever constructed will show. It is that machine now in

91

use, and daily exhibited at the Polytechnic Institution, Regent Street, London, and known
as Mr. Armstrong's hydro- electric machine, that gentleman having been the maker of it,
and its power being derived from the friction of water as above described.

A A A A A A are six green glass supports, 3 feet long. B is a cylindrical tubular
boiler of rolled iron-plate | inch thick ; its extreme length is 7 feet 6 inches, 1 foot of

which is occupied by the smoke chamber, making
the actual length of the boiler 6| feet : its dia-
meter is 3| feet. The furnace D, and ash-hole
C, are contained within the boiler ; and are
furnished with a metal screen to be applied for
the purpose of excluding the light, during the
progress of one class of experiments. F is the
water guage ; E the feed-valve. J J, are two
tubes leading from the valves K K to the two
tubes H. A and I are forty-six bent iron tubes,
terminating in jets ; either half or the whole of
which may be opened by means of the levers
G G. L is a valve for liberating steam during
the existence of the maximum pressure. M is
the safety valve ; N is a cap covering a jet, that
is employed for illustrating a certain mechanical
action of a jet of steam. O is the first portion
of the funnel, P the second portion, which slides
into itself by a telescope joint, so that the boiler
may be insulateJ ..:_:. „Iie experiments commence. The boiler is cased in wood.

The next figure, which may be called the prime conductor, but which is not used for
that purpose, is a zinc case, furnished with four rows of points. It is placed in front of

the jets, in order to collect the electricity from
the ejected vapor ; and thus prevent its returning
to restore the equilibrium of the boiler. The maxi-
mum pressure at the commencement of the ex-
periments is 80 lbs. ; which gradually gets reduced
to 40 or lower. The portion of the apparatus,
•^ which is peculiarly connected with the generation
> of the electricity, is a series of bent tubes with their
:' attached jets. Each jet consists of a brass socket,
I containing a cylindrical piece of partridge wood,
with a circular hole or passage through it, i of an
inch in diameter, into which the steam is admitted through an aperture. The peculiar
shape of this aperture appears to derive its efficacy from the tendency it gives the steam to
spread out in the form of a cup, on entering the wooden pipe, and by that means to bring
it and the particles of water, of which it is the carrier, into very forcible coUision with the
rubbing surface of the wood.

The electricity produced by this engine is not so remarkable for its high intensity,
as for its enormous quantity. In no case, antecedent to this, has the electricity of tension
taken so rapid a stride towards assimilating with galvanic electricity. Mr. Faraday's
experiments on the identity of the electricities had shown how small was the quantity
obtained from the best machines ; and had given good reason to expect that chemical effects
would be exalted when the quantity could be increased. And such is the case here ; a very
remarkable experiment in illustration of this is, that not only is gunpowder ignited by the
passage of the spark, but even paper and wood shavings will be inflamed when placed in the
course of the spark passing between two points — such an effect was never before produced
with C( mmon electricity. In like manner, chemical decompositions are effected much more
readily by means of the hydro- electric, than by that from the common machine. The
current, when passed through a galvanometer, caused the astatic needle to oscillate between
20^ and 30^ ; it also formed an electro-magnet, which deflected a needle. In these various
experiments care is taken to place the conductor very near the jets when quantity is
required, and to remove it beyond the striking distance for intensity.

PAOE

Abb6 Mollefs machine 27

Acid and alkaline effects ... .77

Action, electrical, what 3

Adam"s portable jar 61

vErial electroscope 18

Air thermometer 64

Amalgam, to make 26

Amber, attraction of 4

Animal electricity 88

Atmospheric electricity 82

Attraction, &c 4, 5, 32

Aura, or breeze 45

Aurora borealis 51

Aurora flask, &c 51

Balance discharger 56

Ball, diving, &c 45, 46

Balls and points. &c 42

Barometer luminous 24

Battery 56

Bells ringing or chime 36

Belted bottle 66

Bennetfs doubler 15

Bennett's electroscope 7

Biot's apparatus 41

Board, luminous 74

Boat attracted 39,63

Bomb 65

Brush of light 43

Camphor arborescent 37

Cannon 73

Canoe, repellent 46

Card, pierced 65

Cat, shock from 7

Cavallo's electrometers 83

Cavallo's pistol 71

Chain illuminated 74

Chemical action, excitation by 20

Chime, perpetual 18

Circular rubbing machine 26

• Cleavage, excitation by , 22

Cloud, electrified 34

Cobwebs, sensation of 7

Coin stuck to a jar 66

Colored sparks 49

Condenser 15

Conductors, what, &c. . .4, 23, 25

Configurations 80

Coulomb's electrometer 14

Coulomb's balance 14

Coward's electrometer 64

Crescent, luminous 53

Cross, luminous 47

Crystallization of oil of tartar 77
Culhbertson's plate machine. .31

Cylinder machine 29

De Luc's dry pile 17

De Luc's electroscope 18

Devices on glass 53

Directions of the fluid, &c 66

Director, coated 60

Directors 89

Discharger, balance 56

Discharger, luminous 74

Discharger, universal 65

Discharging electrometer ... .56

Discharging rod 56

Door knob, to electrify 61

Doubler, Benneti's 15

Dry pile 17

Du Kay's system 10

Earthquake, imitated 85

Effects, mechanical, &c 62

Eggs, illuminated 75

Electrical machines 27

INDEX.

PAOE

Electric column 17

Electric fluid, states of 3

Electric light from paper. &c. 7

Paper, adhesion to a wall 5

Paper rent by a shock 65

Pendulum 58

Electrics, whar, &c 4, 23, 25

Electrometers . .13, 39, 56, 64, 83
Electroscope, gold leaf 5, 6, 7, 8

Electroscope balance, &c 5

Electrophorus, &c 26, 79, 80

Electroscope, pendulum 6

Eudiometers 78

Evaporation, excitation by . . . .22

Excitation, modes of 3, 13

Falling stars 85

Feathers, adhesion of 5

Feather driven about the room 6

Feathers, radiating 34

Fiery rain 86

Fish and leaf 35

Flexible tube 63

Flyer with bells 44

Flyers 44

Fort and battery 73

Franklin's system 10

Franklin's <;lo d 87

Franklin's bells 84

Gases, experiments in 52

Gas inflamed .69, 71

Glaciers imitated .' 85

Glass feather 34

Glass plate, &c. excited ..5,6

Gold leaf melted 75

Gunpowder scattered, &c. 72, 74

Hair electrified 6

Hare's wire holder 76

Hawkesbee's machine 27

Head of hair, repellant ......34

Heat, electricity by 21

Henley's electrometer 39

Henley's universal discharger 65

Hydrogen lamp 70

Hydrogen pistol 70

Images, dancing 35

Inclined i)lane 44

Induction, &c 39

Insulation 4

Jar, Leyden 55, 56

Kite 82

Kinuerslcy's air thermometer.. 64

Lateral discharger 67

Leyden jar 54, 55, 61

Light and spark, &c 48

Lightning, cause of, &c 80

Loaf sugar, luminous 7

Machines 27

Magic picture 57

Magic vases 71

Magnet, making of 79

Marks impressed on paper 74

Medical bottle 89

Medical electrometer 56

Medical electricity 88

Metals, excitation of »..24

Nairne's machine 28, 29

Negative electricity, what. ... 10

Non-conductors, what 23

Oranges illuminated 75

Orrery 45

Otto Guericke's machine 27

Pail of water 38

Palmer's machines 31

Perpetual chime 18

pAok

Perpetual motions 9

Phosphorus intlamed P8

Pillars of sand 85

Pith balls moveable 35

Pith balls, to make 36

Planet, revolving 38

Plate machine 31

Plate of air charged 85

Positive electricity, what 10

Powder house 73

Press 65

Pressure, electricity of 16

Prime conductor, what 30

Prismatic colors produced ... .76

Prismatic illumination 69

Pyramid or obelisk 87

Quadrant electrometer 39

Quartz, light from 7

Rain, snow, &c., cause of 85

Reduction of oxydes 76

Repulsion 6. 32

Ribbons, experiments with ... 12

Rope dancer 37

Rosin, inflamed 7

Rubbing machine 26

Sealing wax, attraction of ... . 4

Sealing wax, spun 37

Seesaw 37

Set of spirals 52

Slicrt of glass to charge 57

Shock, how communicated ..55

Shock, explanation of 57

Shot chain 52

Singer's electric column i7

Singer's electroscope, &c . . 8, 9

Spangles, luminous 52

Spider 37. 58

Spiral tube, &c 52,54.74

Spirits of wine, inflamed ....69

Sponge and fountain 38

Sportsman 60

Star of light 43

Steam, electricity of 91

Stockings, experiments with ..12

Stool 89

Sturgeon's perpetual motion . .19

Sugar fractured 65

Sulphur cone 22

Swan, attracted 38

Swing, electrical 36

Symmer's experiments 12

Thunder house 87

Thread.3, diverging, &c 34

Tin, reduction of 77

Tourmalin, experiments with 21

Tube, flexible 63

Universal discharger f>5

Vane and mill work 64

Vessel of oil, to pierce 47

Vermillion, reduction of 76

Vibrations, what 89

Volta's condenser 15

Volta's hydroL'cn lamp 70

Water, composition of 78

Water, decomposition of ....77
* Faraday's apparatus lor 78

Waterspout 86

Watson's machine 28

Whirlwind, imitated 85

Wilson's machine 28

Windmill 45

Wire melted 75

Word, luminous 54

Zamboni's perpetual motion . . 19

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THE ART OF

MODELLING WAXEN FLOWERS, FRUIT,

i'C. ^c. ^c.

Illustrated with Numerous ^Vood Engravings of Moulds, Patterns, Parts of Flowers, Fruit, &c.
By G. W. FRANCIS, P.L.S.

AUTHOR OF THE LITTLE ENGLTSn FLOEA, GHAMMAE OF BOTANY, TAVOEITES OF THE
FLO WEE GAKDEN, ETC. ETC.

Knowing well how much the art of Making Waxen Flowers and Fruit is practised hy
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There are no illustrations of natural objects more exact and pleasing than those made
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THE

DICTIONARY

OF

PRACTICAL RECEIPTS;

CONTAINING

MEDICINAL PREPARATIONS; CHEMICAL OPERATIONS; ARTISTICAL, ORNA-

MENTAL, AND SCIENTIFIC PROCESSES; THE ARCANA OF TRADE

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BY

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KXl'ERIMENTS; THE DICTIONARY OF TRADE, COMMERCE, AND NAVIGATION;

MANUAL OF LEVELLING ; ANALYSIS OF BRITfSH FERNS ; LITTLE

ENGLISH flora; FAVORITES OF THE FLOWER GARDEN;

GRAMMAR OF BOTANY; ETC., ETC.

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and to the Manager of a Family, as a faithful synopsis of numerous operations, and
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and using for some important purpose, a material or preparation which most
frequently cannot be purchased without much trouble and expense.

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CONTENTS OF THE NUMBERS OF THE

DICTIONARY OF PRACTICAL RECEIPTS.

Contents of No. 1. Abemethy's Biscuits— Aber-
nethy's Black Draught — Abemelhy's Medicines — Aber-
nethy's Pills — Abscesses, Acute and Chronic, Treaimpnt
of — Absorption of Moulds, &c. — Absorbent Powders lor
Horses — Accarie's Purified Opium — AocidentH, assistance
in cases of Fracture. Fire, P'rost, Fi's. Drowning or
Hanging. Children in Convulsions, Poisons, Starvation —
Acetic Acid, Glacial or Solid — Acetic Embrocation of
Hartsliorn — Acetic Lotion for Ringworm — Acetate of Lead
Pills — Acidity, to Correct- -Acid Medicines — Acid Soap
—Acidulated Drops — Aconite, Extract of — Acorn Coffee
— Acorus, or Sweet Flag, Oil of — Acoustic Balsam —
Acoustic Oil; Huile Acoustic — Adhesive, or Strapping
Plaister — iEgyptiacum — vEthiop's Mineral — Agrimony
Tea — Ague — Ague Drop, Tasteless — Alabaster, to Work,
to Etch, to Clean, to Join, Staining of. to Preserve Objects,
to Polish — Albata, Aroentine, or German Silver — Albu-
men— Albumen Powder, Flake Albumen, Soluble Solid
Albumen — Albuminous Varnish — Alcohol, to Strengthen
— Ale Brewing — Ale, Amber — Ale from Sugar.

2. Ale from Vegetables — Ale Bitters — Alkaline Medi-
cines— .\lkanet, Extract of — Alkermes Cordial — Alkermes,
Confection and Syrup of — Allspice, Essence of — Alloy —
Almonds, to Blanch — Almond Bloom— Almonds, Burnt —
Almond Cakes — Almonds, Candied — Almonds, Confection
of — Almond Cream — Almond Custard Ice— .Almond Emul-
sion. Milk of Almonds — Alnionds Essence of Bitter — .Al-
mond Flavor — Almond Hard Bake, to make — Almond
Honey Paste — Almond Ice Cream — Almond Icing for
Cakes — Almond Jeliy — Almond Linctus — Almond Mix
ture — .\lmonds Oil of — Almond Oil Soap — Soap of Bitter
Almonds — Almond Paste — Almond Powder — Almond
Powder, French — Almond Rock Cakes — Almond Rout
Cakes — Almond Savoy Cakes — Almonds, Syrup of, Sirop
DOrgeat — Aloes Medicines, Compound Decoction. Ene-
ma. Extractor, Tincture, Pills, Compound; Powder, Tinc-
ture of. Wine — Alterative Medicines, Balls for Horses,
Laxative, for Grease, for Strangles — Alum Baskets and
Ornaments— Alum Baskets, to Color — Alum, Burnt —
Alum, Cubic — .\lum Medicines, Eye Water, Ointment,
Plaister, Poultice, Solution of. Sugared, Wash, Whey —
Alum in Bread to Detect — Alum in Wine to Detect —
Alum Mordant — Alum White — Alumina, or Alum Earth

— Alumina, Acetate of — Amadou, or German Tinder —
Amalgam for Injections — Amalgam Electrical — Amalgam
for Water Gilders — Amalgam Varnish — Amber, to Work

— Amber, to Join and Mend — .Amber, Balsam of — Amber
Varnish, Black— Amber <iold Size — .Amber Varnish, Pale
— Amber and Lac Varnish — Amber Liniment — Amber. Oil
and Resin of — .\mber. Soluble — Ambergris, qualities of.

3. Ambergris, Artificial — Ambergris, Essence of —
Ambergris Hair Powder — Ambergris Perfume — Amber-
gris So:tp — Ambergris, Spirit of — Ambergris Wash Balls
— .\mi)oyna Wood, to Imitate by Painting — Ambretle
Perfume — .\mbrette. Spirit of — American Biscuits — Ame-
rican Blight, Cure for — American Mead — .Amethyst Paste
— Ammoniacal Preparations, Acetate of. Embrocation,
Liniment, Plaister, Spirit of. Aromatic Spirit of. Com-
pound Spirit of. Foetid Spirit of, Succinated Spirit of.
Lavender Water — Ammoniacum, Essence of — Ammoni-
acum. Fomentation of — Ammoniacum, Mixture o' — Ana.
tomical Preparations — Anatomical Injections — .Anchovies
British — .^n<;hovy. Essence of — Anchovies, Transparent
Essence of — Anchovy Powder— Anderson's Scotch Pills
— Angelica Green, to <^.andy — Angelica. Spirit of — Ange-
lica Cream — .Angel Water— Animal Charcoal — Anise —
Anise Creme — .Anise Powder — Aniseed, Balsam of — Ani-
seed Cordial — Anisette de Bordeaux — Annatto, English —
Annatto Puritied — Annatto to Dye Wool with — Annatto
to Dye SilK — Annatto to Dye Cotton — ."Vunatto to Color
Cheese — Anodyne Medicines, Bolus, Drops, Enema,
Essence, Fomentation, Julep, Mixture. Liniment, Poul-
tice, Necklaces — Anodyne Ball for Horses — Anodyne
Drench for Horses — Antacid Medicines, Draughts, Mix-
lure. Powder — Anii- Asthmatic Powder — Anti-Attrition
Paste — Anti-Bilious .Medicines — Anti-Emetic Medicines
— Anticardium — Antimonial Powder — Antimony, Regulus
of — Antimonial Wine — Anti-Scorbutic Medicines, Infu-
sion, Mixture, Juices, Wine — Ami-Septic Medicines,
Draught. Komentatron, Oargle, Mixture — Anti-Spasmodic
Mediiines, Draught. Enema, Vlixture.s, Pills — Ants, to De-
stroy— .\perienl Medicines, Draught. Powder, IMlls, He. —
Apiary, to Establish — Apoplectic Balsam — Apoplexy.

4. Apples, to Preserve — Apples, to Dry — Apple Bis-
cuits— Apple Bread— Apple Cheese — Apple Jelly — .Apple
Marmalade — Apple Paste — Apple Sugar — Apple-tree
Canker, to Cure — Apple- water Ice, Apple Ice Cream—
.Api>le Wine, White, Bed — Apricots, Green, to Preserve-
Apricots, Ripe, to Preserve — Apricot Biscuit — Apricot Ice
— Apricot Paste — Apricot Wine — Aquafortis, Single,
Double, Strong, Spirit of Nitre, Dilute, Proof, Compound
— .\qua Potens — .Aqua Kegia — Arabic Gum. to Clioose
and Test — Archil or Orchil — Archil, to Dye Wool — Ar-
chil, to Dye Silks — .^rgentum Musivum — Armenian Ce-
ment, or Turkish Glue — Aromatic Medicines, Confection,
Draught, Electuary, Fomentation, Mixture, Plaister, Pills,
Powder, Tincture — Aromatic Spirit of Ether — .Aromatic
Vinegar — Arquebusade Water — Arrack, .Mock, or Vaux-
hall Nectar— Arrow Root, to Test — Arrow Root, British
— .Arsenical Paste — Arsenical Soap — Asarabacca SnufT —
Asiatic Dentifrice — .Asphaltic Mastic — Assafoeiida, Emul-
sion of — .As3;>foetida .Mixture — Assafoetida Pills — \ssa-
foBtida Plaister — Assafoeiida, Tincture of — Assayer's Acid
— Assayer's Muriatic Acid — Assayer's Fluxes, Crude or
White Flux, Black Flux. Cornish Reducing Flux. Cor-
nish Kehning V\ux — .Asses' Milk, Artificial — Asthma —
.Asthmatic Elixir — Astringent Medicines, Draught, Ene-
ma, Fomentation. Gargle, Infusion, Lotion, Mixture,
Ointment. Pills — .Astringent Cattle Medicines, BhIIs for
Horses. Drench for Hor.ses, Enema or Clyster for Horses,
Ointment for Horses. Powder for Horses — Ausburgh
Beer — .Auld -Man's Milk — Aurum Musiyum — Auruin So-
phisticum — .Austrian Wine — Azure Blue.

5. Bacon, to Cure — Badigeon, to Make — Badolier's
Vinegar — Bailey's Itch Ointment — Baldness, to Cure,
Oil for. Pomatum for, Wash for — Baldwin's Phosphorus
— Balloons from Tarkeys' Crop.s — Balloons, Varnishes
for — Bailey's Digestive Draught — Balsamic Vinegar —
Balm Water — Balm Wine — Balsamic Injection — Balsa-
mic Powder — Banbury Cakes — Bandoline for the Hair —
Barbadoes Cream— IJarbadoes Water— Barberry Cream
— Barberries, to Preserve — Barberry Drojis — Jelly — Bar-
clay's Antibilious Pills — Barege V\ ater — Bark Peruvian,
Tm«ture of. Compound, Simple. Concentrated— Barker's
Tooth Tincture — Barley Bannocks — Barley Sugar —
Barley Su^ar Drops, or Kisses — Barley Water — Barn-
stable .Ale, to Brew — Basil Wine and Vinegar — Basilicon
Ointment — Basilicon Powder — Bass's Pale Ale, In<lia
Ale. ice. — Bates's .Anodyne Balsam — Ba eman's Pectoral
Drops— Uates'a Stiptic VVash— Bath Bricks— Bath Buns—
Balh Cakes — Bath or Liquorice Pipe — Batteries. Solu-
lulions for. Dmiell's Battery, Gro»'e's Battery, Leesons
Battery, Smee's Battery, Sturgeon's Battery, Wheat-
stones Battery — Battley's Green Senna Powder — Batt-
ley's Liquor Opii Sedativus — Bavarian Ale — Baume's
Spirit of Wine — Bays. Oil of — Bear's Grease — Beauty
Water — Bedford Biscuits — Bee. Sting of, to Cure — Beech
Black — Beer — Beer for the Table — Beer from Sugar or
Treacle— Beer from Pea Shells — Beer, to Improve —
Beer, to Prevent Acidity in — Beer, to render Intoxicating
— Beer, when Foxed, lo Restore — Beer, when Frosted,
to Restore— Beer to Restore when Sour, Flat, &c.— Beer
Bottled to Ripen.

6. Beer Poultice — Beet Root Sugar— BeJadonna,
Tincture of— Bell .Metal— Belloste's Pills— Bell's Bougees

— Bending Glass Tubes — Benjamin, Flowers of — Benzoin,
Tincture of — Bergamot, Oil of — Bergamot Perfume —
Bergamot Water — Berlin Green — Berlin Vinegar — Ber-
ries, Wine from — Bestucheffs Nervous Tincture — Bice,
Bidilery Ware — Bilberry Wine — Birch Oil — Birch Tree
Sugar — Birch Wine — Bird Lime — Birds in Gardens, ic —
Biscottes de Bruxelles — Biscuits, to make — Biscuit Drops
— Biscuits of Fruit — Biscuits, Purgative — Bishop- Bistre
Bitters, Medicinal — Bitters for Liqueurs, Ike. — Black-ash
— Black Chalk — Black Composition — Black Drop — Black
Dyes— Black Draught— Black Enamel— Black Flux-
Blacking for Shoes, 6ic. — Blacking Cakes — Blacking Balls
— Blacking the E.lges of Books and Paper — Black Japan

— Black Lozenges — Black Reviver — Black Varnish for
Metal— Blackberry Wine — Black Lead Pencils, artificial
— Black LeadDr.^.wings, to Fix — Blad.lers, &c. to Prepare
— Blaine's Powder — Blanched Copper — Blancmange —
Bleaching Liquid — bleaching Liquid Extemporaneous —
Bleeding; at the Nose— Blight on Rose Trees, to Destroy
—Blistered Fuel. Cure for— Blister Liquid— Blister Plaster
-^Blisters for Horses,

CONTENTS OF THE NUMBERS OF THE

DICTIONARY OF PRACTICAL RECEIPTS,

Contents of No. 7. Blond Lace, to Blanch— Blood,
Powdered — Biood Cement — Blood, Spitting of — lilue
Ashes— Blue Black— Blue Dyes, for Cotton. Silk, Wood ;
Hone, Ivory and Feathers — Blue Enamel — Blue Kve
W.iter— Hlue Fire— Blue MottledWash Balls— Blue Oiiit-
meni — Blue Paints, for House Paiming, Artists, Water
Colors. Distemper — Blue, or Mercurial Pill — Blue Signal
Lights, Bengal Lights — Blue Stone or Blue Vitriol —Pale
Colored— Blue Verditer—BlueWriting Ink— Boerhaave's
Astringent Powder — Boerhaave"s Red Pill — Bohemian
Glass, Crown, Flint, Plate — Boiled and Baked Oil — Boils
— Bologna 1 hosphorus — Bologna Sausages — Bologna
Wash Balls — Bon Bons— Bone Black, Dye.s for Bed,
Scarlet, Black, Purple. Yellow. Brown, Blue, Green —
Bone Glue — Bone Grease — Books. Gilding the Edges —
Books, Lettering the Backs — Books, to remove Stains
from — Boot Powder — B^ot Varnish — Boots, Waterproof-
ing— Boot Tops, to Clean — Borax, Gurgle — Borax, Glass
of — Bordeaux, or Parisian Cakes — Bordeaux, Imitative —
Bosse's Hard Varnish — Botany-bay Cement — BottleGlass
— Bottling of Malt Liquors — Bolts in Horses — Bougie —
Bougavil. White — Bouquet de laReire — Bouquet Water
— Box-Wood for Engraving, to Choose, to Prepare, to
Draw upon — Boyle's Depilatory — Boyle's Fuming Liquor
— Bramble Biscuits — Bran Bread, to make — Brandy,
British — Brandy from Beet Root, to make — Brandy from
Potatoes, to make — Brandy, to give apparent Age to —
Brandy, to give a Bead to — Brandy Balls — Brandy
BUiers — Brandy Flavor — Brandy Shrub.

No. 8. Brass — Brass Ornaments to Preserve — Brass

"Work. Bronzing — Brass, Pa.stes for Cleaning — Brazil
Snuff— Brazil Wood Lakes— Brazil Wood. Tincture of—
Bread, to make, on Cobbett's Plan — Bread, to Prepare in
the Method of the London Bakers — Bread Excllent. to
make — Bread from American F'lour — Bread, to Detect
Adulteration in — Bread without Yeast — Broad Seals —
Breakfast Powder — Brea'li, to Sweeten — Bree's Anti-
Asthmatic Plaister — Breeches Ball — Bremen Green —
Brewing — Brewing t'tensils, to Preserve — Brick, Oil of
^-Brick, Oil of. Fictitious — Brilliant Composition for
Fire-Works— Britannia Metal, or Tutania— British Gum
— British Oil — British Tooth Ponder — Broduin's Nervous
Cordial — BrokenKnoes of Ilorse.s — Bronze, for Statuary,
for Medals, for Cutting Instruments, for Mortars, foe
Ornaments — Bronze of the Ancienis— Bronze Liquids —
Bronze, to Darken — Bronze Powders — Bronze to, with
Oil Color — Bronze, Printing in — Bronzing. Cleaning for —
Brown Dyes, for Cotton, for Silk, for Wool, for Wood —
Brown Enamel — Brown Paints, for House Painting. Ar-
tist's Colors, Water Colors — Brown of Prussian Blue —
Brown Pink— Brown Ointment — Browning for Cookery —
Browning of Gun Barrels--Brucine Pills-- Bruises — Bruises
of Horses — Brunswick Black Cheap — Brunswick Green
— Buccaned Meat — Buckthorn, Syrup of — Bug Poisons —
Bull's Eyes — Bunions.

No. 9. Buns — Burgundy Pitch Plaister— Burns and
Scalds — Burnt Sugar. Solution of — Burton Ale. to make
a Hogshead of — Butter, to Clarify — Butter, to Improve —
Butter, to Preserve — Bu ter preserved wiih Honey —
Butler, to Pack — Butter Biscuits — Butterflies, to Take
Impressions of — Buxton Water — Butter of Antimony —
Cacao — Cajeput, Liniment of — Cajeput, Oil of— Cajeput.
Opodeldoc — Cake — Calamine, Prepared — Calamine Ce-
rate or Ointment, Simple, Compound — Callot's Soft
Engraver's Varnish — Calomel, to Test if Pure— Calomel
Pills — Calomel, Flowers of — Calomel Ointment — Calo-
type Paper — Caluinbo Bitters— Calves to Bear, without
the Cow — Camomile Drops — Camomile, Essence of —
Campbell's Green Liniment — Cameos, &c. to Carve —
Camphorated Chalk. Varnishes. Copal. Sandarac, Spirit,
Vinegar, Wine, — Camphor Balls, Balls in Farriery, Cake,
Liniments, Simple, Compound, Draught, Drink for Horses,
Emulsion Ointment, Mixture — Camp Vinegar — Canals,
Cement for — Candied Sugar — Candles, to Make — Can-
tharides. Oil of. Tincture of— Canton's Phosphorus — Can-
ker in Apple Trees, to Cure — Canvas Prepared fur Painters
— Caouchoucine, how Prepared — Caouchoucine. to De-
prive of Odour — Caoutchouc. Liquid — Caouichouc, sol-
vents for — Caoutchouc, Varnish — Caoutchouc Balloons —
Capeis, French, English — Capillaire — Capsicum Spirits
of — Capsules for Medicine — Captain's Biscuits — ^aramel
Sugar — Caratch Sauce — Carbonated Lime Water — Car-
damon. Tincture of. Simple and Compound — Cardamon
Water — Carmine, to Prepare, Adulteration in. Liquid,
Blue, Purified, Lake from Madder.

No. lO. Carminated Lake for Crayons— Carmina-
tive Medicines Drinks for Cattle — Carraway Brandy,
Cordial, Water, Comfits — Cascarilla, Tincture of. Water
— Casks, Seasoning of when New, to Sweeten when
Musty, Match for Sweetening — Cassel and Cologne Earths
— Cassia. Electuary of. Conserve of— Cassis, Batifia de —
Cassius, Purple Precipitate of- -Castile Soap, English
Imitation of — Castor. Tinctures of, Oil Clyster, Oil
Draught— Case Hardening— Catchup, Mushroom, for Sea
Store — Caterpillars, to Prevent their Ravages— Calachu
Ointment, Tincture of, Confecti<>n of. Lozenges, to Make
—Cathartics. Pills— C:itheter — Catherine Wheels— Ca-
tholicon Duplicatum Rheo. P.— Cauliflowers, to Pickle
— Caustic Medicines, Common, Mild, Lunar, Liquid,
Opiate ; for Canker in Horses — Cayenne Pepper, Reduced.
Prepared, Essence of. Brandy, Wine, and Vinegar— Ce-
drat Cordial, Essence of — Celery, Essence of — Cement —
Cephalic Snuff, Plaister — Cerate, Simple — Ceru.^e Oint-
ment— Chalk, Compound Powder of. Precipitated. Pre
pared— Chalybeate Pills. Iron Powder. Water Artificial,
Wine — Chamberlain's Restorative Pills — Chnmpagne,
Imitation of — Charcoal, to Make. Crayons for Drawing,
Poultice — Cheese Cakes. Cement— Chelsea Pensioner,
Buns— Cheltenham Salts, Water. Imitative —Chemical
Wash Balls — Cnemists' Bottles, Colors for.

No. 11. Cherry Bounce or Brandy, English. Imita-
tive, American, French, Water, Wine — Cheshire Cheese,
to make: Salt, Basket, Common, Bay, Fishery — Chival-
licr's Alcohol— Chevenix's Antimonial Powder— Chian
Turpentine, Fictuiou.s — Chicken Pox — Chilblains. Lo-
tions for. Ointments for — Chille Vinegar — China or Glass,
Cement for — China Ink. Locksoy — Chinese Composition
for Japan Work, Fires for Fireworks, Flyers, Paste, Pro-
pagation of Fruit Trees, Sheet Lead, Yeilow, to make

Chings Worm Lozenges— Chintz, to Wash— Chlorinated
Soda — Chlorine Gas or Liquid — Chocolate — Chocolat a la
Vanille — Chocolate Stomachic. Brandy, Drops, Cream, Ice
— Chrome Red. Yellow — Cider, to make, from Raisins, to
Improve, Champagne, Wine — Cinnamon Cakea, Comfits,
Cordial, Lozenges, Soap. Syrup of. Water and Spirit —
Circassian Cream, Citric Acid — Citron Cordial, Oil of.
Peel, Candie«l — Citronella — Clairet, Rossalie de six
Grains— Clarence B.scuits— Claret Rags, Imitative, to
Darken, to Fine, to Manage, when Foul to Restore—
Clarifying Powder.

No. 12. Clary Wine — Clater's Drink for Sheep-
Cleansing Poultice for Cattle— Cloth Clothes, to Scour

Clothes, to Perfume, to Preserve, Ball, Powder— Clotted
Cream — Clove Cordial, Pinks, Extract and Syrup of.
Lozenges— Clover Sped, to Detect Doctored— Clutton's
Febrifuge Spirit— Cluzell's Kerme.s— Coal Balls— Cobalt
Blue — Cochineal, Syrup of. Wash Balls — Cochrane's
Cough Medicine — Cockroaches, to Destroy— Coffee Bis-
cuits. Milk. Ice, Ratafia, Substitutes for, Corsica, Cur-
rant. Egyptian, American. Holly, Broom. Rice, German,

French, Rosetta, Rye. Iris, Sassafra.s — Coindet's Pills

Coins of Sulphur. Moulds for — to Make — Colchicum,
Powder of. Tincture of. Vinegar — Cold or Catarrh — Cold
Cement. Cream — Colepresse's Cider — Colic Ball for
Horses — CoUett's Tooth Ache Drops — Colley's Depila-
tory— Colocynth Clyster— Coloring for Liquors— Com-
position Ornaments — Comfits — Concrete — Confectionary
— Congreve Lucifers — Constant White — Contrayerva
Pills. Powder— Copaiba Balsam, Mixture of. Salts of—
Copal, Solvents for. Varnishes— Copper for Engraving,
to Gild, to Tin, Medallions, Plates, Copper Plate Printing
Inks— Copperas, Green, Green Vitriol Calcined, Water.

No. 13. Copying Machine — Coral for Grottos,
Powder, Syrup, Tooth Powder —Cordial Ma.ss Corian-
der Cordial — Cornachin Pills — Corn to Preserve — Corne-
lian— Cornish Fluxes, &c. — Corns — Corrosive Sublimate
— Cosmetic— Costorphin Cream — Cotton Goods. Bleach-
ing of— Cough, Medicine for. Lozenges,— Court Plaister
— Cowslip Mead, Wine — Coventry Cakes — Crackers —
Cracknels— Cramp in Bathing, in the Leg. in theS'omach
—Cranberry Jelly— Crayons foi Drawing, Colors for.
White, Carmine and Lake, Vermillion, Y'ellows, Blue,
Browns, Greens, Black, I'aste for. Method of making,
Marks, to Erase, Drawings, to Fix, for Drawing on Glass
—Cream. Iced, of Tartar. Balls, of Roses. Substitute for
— Crespit^ny's Pills— Crickets, to Poison— Crimson, to Dye
Silk— Crocus, of Gold, of Iron, of Antimony— Cross Buns r.„t

— Croton. Tincture of- Crows from a Field, to Ba.ii.sh ,„

—Crucibles, Composition of— Crumpets— Crystal Giass,
Powder, of Tartar — Crystallized Microscopic Objects.

CONTENTS OF THE NUMBERS OF THE

DICTIONARY OF PRACTICAL RECEIPTS,

Contents of No. 14-. Crystallized Windows —
Crystals of Salts, Varnish — Cubebs. Tincture of — Cucum-
bers, to Piokfe. Vinegar — Culley's Salve for Rot in Siieep
— Cumin Plaister, Water — Cup Cakes — Curd for Cheese
— Cheese Cakes, Soap — Curling Fluid — Cura9oa — Cui
rant Clear Cakes, Jam, Jelly, Shrub, Wine — Curry
Powder, Imitative, Wine, Lord Clive's Powder — Cutler's
Cement — Custards — Cuts — Cypress Powder, Gross —
Cyprus Wine, to Imitate — Cyrillo Pomatum — Daffy's
Elixir — Daguerre's Photogenic Paper — Damask Powders
— Dampness in Beds, to Detect — Damp Walls — Damsons
to Bottle, Cheese, Wine — D'Arcey's Digestive Lozenges
— Dead Fire for Fireworks — Deafness — De Brun's Eye-
Water — Decanters, to Clean — De la Motfe's Golden
Drops — Uelcroix's Povvdre Subtile — Delescotfs Myrtle
Opiate — Demulcent Electuary — Dentifrice Electuary —
Depilatories — Derbyshire Spar, Cement for — Detergent
Medicines — Devil's Elixir — Devonshire Cider — Dextrine

— Diachylon Plaister — Diagrydium — Diamonds, Paste
for — Diaphoenix Electuary — Diaphoretic Antimony —
Diarrhoea, to Check.

No- 15. Diet Drinks — Digestive Lozenges, Medi-
cines— Dinner Pills — Dippel's Oil of Hartshorn, Acid
Elixir — Discharge, Colors to — Distemper in Dogs, among
Cattle — Distillation of Simple Waters, to Preserve
Flovvers, for— Diuretic Medicines, Balls for Horses, Salt

— Dixon"s Antibilious Pills — Dolfuss' Acetous Acid —
Dolichos, I^lectuary of — Donovan's Mercurial Ointment

— Dorchester Ale — Doses, to Regulate — Dover's Powder
— Dragon's Blood, Fictitious — Drowning Recovery from.
Stripping, Removal of the Body, Warmth, Fresh Air,
Inflation, Fomentations, Cordials, Bleedino — Drunken-
ness, Recovery from — Drying Oils for the Painters —
Du|)uytrens Eye Salve— Durietz's Anti-Hysteric Elixir
— Dutch Cinnabar, Drops, Pinks, Terras — Dyer's Aqua
fortis. Spirit — Dysentery — Ear- Ache — Earthenware,
Enamel for — Ear- Wigs, Traps for — East India Pills, Tan-
jore Pills — East India Pomatum — Eaton's Styptic Wash
— Eau D'Arguebusade, de Bouquet, de Cologne, de Luce,
d« Marechale, de JMelisse des Carmes, de Mille-Fieurs,
Divine, Sanspareil — Eccles Cakes — Edinburgh Ale —
Itch Ointment — Efl'ervescing Emulsion, Poultice — Eggs,
Pickled, to Preserve, Flip — EgyiJtian Azure — Elder
Brandy, Flower Wine, Ointment, Wine — Elecampagne.
or Candy Cake.

No. 16. Electrical Cement, Varnish — Elephant's
Milk — Elixir of Vitriol — Embrocation, Common — Eme-
ralds, Imitative — Emetics— Emollient Enema, Poultice

— Enamel for Saucepans, &c. — Encaustic Painting,
Medium for — Enema, Common — Engineer's Cement

— English Verdigris — Enuraviugs, Cleaning of — En-
graviuifs, to Transfer to Plaster — Epilepsy, Electuary
tor — Ergot, Essential Solution of — Escharotics — Essen-
tia Bina — Essex Ale to Brew — Etching Acids, for
Biting in, for Copper, for Glass, for Marble and Stone —
Etching Ground — Etching Ground, to Lay — Etching on
Glass, a Varnish (or Covering preparatory to — Exihe-
(piar Ink — Kxeter Oil— Extempore Smelling Salts — Eye
Sah'c — Eye Snuff— Eye Waters — Face, to Take a Cast
from — Fainting Fits, to Recover from— Fancy Biscuits, to
make — Farcy Balls for Horses — Feathers for Bedding to
Cleanse — Feathers for Ornamenis, to Prepare — Fenouil-
lette— Fetid Pills for Hysterics— Fever Ball for Horses,
Fever I'owder for Horses — Fermentaiiou, to Manage —
Fermentation. Accelerators of^ — Fermentation, to Check
or Stop — Fever— Field's Extract of Vermillion — Figures,
of Varnishing — Filberts, to Preserve — Filters, to make.

No. 17. Filtering Bag — Filtering Machine — Fin-
cham's Purifying and Disinfecting Liquid — Finings, for
Beer or Ale — Fire, to Escape from — Fire and Water-
Proof Cement — Fue-Proof Paint — Fire Proof Stucco —
Fish, to Preserve with Oil, Acid, Creosote, Sugar — Fish,
to Preserve Alive — Fish Oil Paints — Fit Drups — Fixature
for the Hair — Flake White — Flash — Flatulence, Remedy
for — Flemish Glue — Flexible Paint — Flint Glass, Com-
position of — Florentine Lake, to Prepare — Floors, Cement
for — Florey B ack — Flour, to Dete<;t Adulterations in —
Flour I'aste. to make — Flower of Ointments — Flowers,
to Restore — Flowers, to Extract the Perfume of— Fluid
Magnesia — Flute Key Valves — Fluxes — Flux, Remedy
Jor— Fluxes for Enamels — Fly in Sheep — Fly on Turnips,
}^o Destroy- Fly Water— Foils, to Make— Foils, to Silver
f — Foils to Color — Foliage, Plaster Casts of — Fomentations
— Ford's Laudanum — Foreign Wine- Fossil Woo>is for
the Microscope — FothorgiU's Pills — Fox's Cream for the
Hair— '.".-acturcd Limbs.

NO- 18. Frankfort Black— Freckles and Sunburns

-Freeman's Bathing Spirits — Freezing Mixtures for
making Ice Artificially — French Cement — French Glue
— French Oil for Furniture — French Polishing, &c. —
French Pomaae — French Red, French Sealing Wax —
Fresco, Colors for — Friar's Balsam, &c. — Frit — Fronti-
niac. Imitative — Fruit Biscuits — Fruits, to Bottle — Fuel.
Manufactured — Fuligokali — Fulminating Powder, to
make — Fulton's Decorticated Pepper — Fumigating Pas-
tiles — Foul Rooms to Fumigate — Furniture Polishes —
Furs, to Preserve — Fuse for Military Shells — Fusees, to
make — Fusible Alloys — Fusible Metal. Casts from — Gal-

banum, Plaister of. kc. — Gall, to Purify for the Artist

Gall Drops — Gall Opodeldoc — Gall Stone, an Artist's
Color— Gall, Syrup of— Gallipot Varnish — Galls Oint-
ment, &c. — Galvanized Iron — Gamboge Pills — Gargle,
Commom — Garlic Balls for Horses — Garlic, Syrup of —
Garlic Vinegar— Garnets, Artificial— Gascoigne's Powder
— Gelatine — Gelatine from Bones — Gem Cutter's Paste —
Gems, Red Sulphur — Gentian, Infusion of,iic. — German
Blacking — German Paste — Gilder's Varnisu — Gilding.

No. 19. Gilding Liquid or Pickle— Gilding Metal
or Alloy— Gilding Wax — Gilead, Balm of. Factitious —
Gin — Gin, Finings for — Ginger Beer in Bottles — Ginger-
bread— Ginger Cakes — Ginger, Essence or Tincture of —
i Ginger, to Candy — Ginger Candy — Ginger Lozenges —
j Ginger Candy and Drops— Ginger to Preserve — Ginger
, Powders — Ginger, Mock Preserved — Ginger Brandy or
{ Cordial— Ginger, Syrup of — Giii;;er Wine — Glaire—
Glass, Cutting and Breaking of — Glass, to Drill, for
Thermometers — Glass and Porcelain, to Gild — Gla.ss, to
Powder — Glass, to render Opaque — Glass Bottles to
Clean — Glass, Staining of — Glass, Staiiiiiij^ Colors for,
F^lesh, Black, Brown, Red, Rose Color, Bistre and Brown
Red, Green, Yellow, Orange, Purple, Biue — Glass Cloth
and Paper — Glass Grinder's Cement.

No. 20. Glass Seals— Glauber's Tincture of Iron-
Glaze for Pottery Ware ; for Porcelain, White Ware,
Printed Ware, I'aintcd Ware, Raw Glazes, Ironstone
Ware, Green Ware, Red Pottery Ware — Glaze for
Cooking — Glazed Boards, to Clean — Glazier's Putty —
Gloves, to Clean ; Kid Gloves, Doe or Buckskin Gloves
— Gloves to Dye — Gloves, Perfumes for — Glues — Glue
Cement — Glue Varnish — Godbold's Vegetable Balsam —
Godfrey's Cordial — Godfrey's Smelling Salts — Gold
Allocs — Gold Articles, to Cleanse — Gold, lo Color, Green,
Red— Gold Cordial— Gold Beater's Skin— Gold Ink—
Gold-colored Lacker — Gold Lace and Embroidery, to
Clean — Gold, Liquid or Potable — (iold Powder — (iold
Rain— Gold Sealing Wax — Gold Shells— Gold Size-
Gold, Solder for — Gold Varnish for Leather — Goose-
berries, lo Keep — Goosebirry Champagne — Gooseberry
Cheese — Gooseberry Ice — (Jooseberry Jam — Gooseberry
Jelly — Gooseberry Marasquin — Gooseberry Vinegar —
Gooseberry Wine — Goulard's Extract of Lead— (iou-
lard's Eye Water — Goulard's Liniment — Goulards Oint-
ment— Goulard Poultice — Gouttems Aeres — Gout, Cor-
dial, Lincius, Liniment — Grapes, to Preserve — Grape
Wine — Gravel — Grease from Cloth, to Remove — Greaiie
from Paper, to Remove.

No. 21. Grease from Silks, to Extract — Grease of
Horses Heels — Grecian Water — Green Balsam — Green
Bice— Green Dyes — Green Dye for Black Cloth — Green
Fly, lo Destroy — Green Ink — Green Oil — Green Oint-
ment— Green Precipitate — Green Sealinij Wax — Green
Tooth Powder — Green Liniment — Greenough's Tincture
for the Teeth — Greeu Paints — Gregory's Powder — Gren s
Benzoic Acid — Grenoble Ratafie — Grey Lotion — Grey
Dyes — Grey Colored Fire — Grithn's Tinciure — Grind-
stones, Artificial — (irindle's Cough Drops — Gripes in
Horses, Remedies for — Grosvcnor's Tooth Powder —
Guaiacum. Infusion of — Guaiacum Mixture — Guaiacum
Tincture of — Guestonian Embrocation— Guido's Balsam
Gum Anglicum — Gum Arabic, Mucilage of, Emulsion —
Gum Julep, Lozenges and Pastiles, Paste for Comfits,
Plaister, Seals — Gumption for Artists — Gun Powder, to
make. Barrels, Browning of, Cotton, iletal — Gut, for
Anglers— Guthrie's Black Ointment — Guthrie's Eye Oint-
ment— Guy's Powder of Ethiopia — Guyot's Spirit — Hah-
iieman's Wine Test — Halford's Sir H. Nervous Tincture
Hair for Wigs, to Prepare— Hair. Superfluous, to Remove
— Hair, to Sort and Clean.se — Hair to UleaL-h— Hair to Dye
— ilair Powder, for Lime, Rice, Flour, &c. — Hair Powder
Perfume — Ilamliurgh Pickle — Hams, to Cure — Ilame-
lin's Cement, to Make— TIniid GrtMiado — ll.tnman's Hair
Dye— Hard C ' . ;■ ' n> -•• \ V

CONTENTS OF THE NUMBERS OF THE

DICTIONARY OF PRACTICAL RECEIPTS,

Contents of No. 22. Harness Maker's Jet an 1
Paste — Hartshorn, Burnt, Drink, Shavings, Jelly, and
Spirit (>f — Hatfield's Gout Tincture — Hats. Stiffening and
D>e f(>r — Hay Stacks — Headache — Heading for Beer —
Healing Poultice for Cattle — Heartburn Lozennes, &c —
Hellebore, Extract, Infusion, Ointment, and Tincture of —
Helmont's Elixir of Proiiriety — Heinet's Dcntrifice —
Hemlock, Extract, Infusion, Ointment, Pills, and Tinc-
ture of — Heni)ane, Extract, Ointment, and Tincture of —
Henry's Ammonia Water, Aromatic Vinegar. INIajjuesia,
Potass Water, and Soda Water — Herpes — Hiccough —
Herrenschaund's AVorm Specific — Hides, to Tan — Hiera
Picra — Higgins's Cement — HilTs Oil of Vitriol — Hippo-
eras — Hoarseness — HolTman's Pills — Hollands Gin —
Holy Thistle, Infusion of — Homberg's P^rophorus —
Honey, to Choose, Clarify, Cerate, Water, and Balsam of
— Hooper's Pills — Hooping Cough — Hops, Extract. Infu-
sion, and Tincture of — Hfrehound, to Candy, Infusion,
and SyruD^of — Horn, to Dye and Stain — Horse-hair, to
Curl and Dye — Horse-radish, Gargle, Infusion, Powder,
Vinegar, Spice, and Spirit of, &c.

No. i23- Hot Cement — House Painting, Colors for —
Hiiiles Antiques, L'Orange, L'llose La Tuberose, De
Venus, and Liquereuses — Hungarian Liniment— Hungary
Water — Huxharn's Bjrk Tincture — Hyposulpliue of S'>da
— Hysterics — Ices, Ice Cream, and Iceing for Cakes —
Iceland Moss Jelly — Illumination Fire — Impenetrable
Mortar — Imperial Drinks and Liquids for the Hair —
In.tantations, Theatrical — Indestiuctible Ink — Indian
Cement and Corn Foods — Indian Hemp, Tincture and
Extract of, and Lozenges — Indian Ink, to Choose and
Imitate — Indian-rubber Blacking Tubes, Oil, &c. —
Indigestion — Indigo, to Prepare and Obtain, Blue and
Sulphate of— Infant's Preservative — Inflammation.

No. 24. Influenza — Infusions — Injections, Metallic
— Ink, Black — Intoxication, Insensibility and Apparent
Death from — Insecls. Bites and Stings of — Iodine, Solu-
tion of — Iodine and loduretted Medicines— Ipecacuanha
Linctus. Lozenges, Pills, Powder, Tincture, and Extract
of— Irisn Moss Jelly — Iron Cement, Gilding, Liquor,
and Sand — Iron, Medicines of — Iron to Tin, and preserve
from Rust — Iron-Work Blace — Iron Plates, Tinning of —
Isinglass Cement, iic. &c.

No. 25. Isinglass Glue, Jelly, and Mucilage — Issue
Peas and l-'laisters — Italian Bre.id, Cream, and Varnish —
Itch — Ivory Black, to make — Ivory, to Bleach. Dye,
Etch, Smooth. &c.— Ivory Jelly— Jackson's Itch Oint-
ment— Jalap, Draught, Elixir, and Powder of — Jamaica
Pepper Water — James's Analeptic Pills and Powder —
Jams of Fruit, to keep from Moucd — Janin's Eye Oint-
ment— Japan for Leather and Tin-ware — Japan Gold
Size and Ink — Japanese Cement — Japaniier's Copal Var-
nish—Jasmine, Essence and Oil of. Hair Powder, Po-
matum, and Water— Jaundice in Cattle and Horses —
Jaunemange — Javelle, Eau de — Jellies— Jesuit's Drops —
Jets of Fire — Jeweller's Rouge — Jordan's Balm of Ra-
kasiri — Josse's Purified Opium — Julin's Aquafortis —
Juniper Berries, Decoction, Infusion, Extract, Oil, and
Spirit of — Jujube Paste — Kali Praeparatum — Keene's
Marble Cemeni — Kemp's White.

No. 26. Kennedy's Corn Plaister— Kennett Ale—
Kermes Lozenges and Minerals — Kersey's Pills — Kid
Glove Cleaner — Kidder's Sweet Sauce andSavoury Spice
— King's Cordial and Yellow — Kino Imitative and Powder
— Kirkland's Neutral Cerate — Kirschwas.ser — Kitchen
Pepper— Kitchiner's Essence of Herbs, Pills, Eelish and
Superlative Sauce — Knox's Disinlecting Powder — Kcech-
lin's Liquid — Koumiss — Knuckel's Phosphorus — Kuseque
Powder Kuslitien's Metal for Tinning — Labdanum Spu-
rious— Labels of Botues, to preserve — Lac to Bleach, Lake,
Spirit, and Tincture of — Lac-water Varnish — Lixquer
for Brass, for Tin, and for Philosophical Instruments —
Lacquering, to prepare Brass for, of Old Work, and Pro-
cess of — Lactate of Iron Lozenges— Lactic xluid Lozenges
— Lady Kent's Powder — Laenneo's Sedative Drauuht,
and Remedy for Tooth-Ache— La Fayette's Cakes— Lake
Colors — Lamp Black— Langelolte's Prepared Opium —
Lapis Divinus, and Medicamentosus — Lard— Lurdner's
Prepared Charcoal— Lasteyrie's Lithography Ink— Lau
danum, and of Quinces — Laughing Nuts — Laurel Oint-
ment— Lavender Drops, Vinegar, Oil of. Water, and
Ammoniacal — Laxative Medicines, Balls for Cattle —
Drenches for Cattle— Lead as a Poison, in Wines— Dust
and Grains Lotion of, Plaister, and Lead Tree — Leake's
Pills— Leather, Dyeing of.

No, 27. Leather, to Clean, &c. — Leaves, Casting, &c.
— Le Blonds Varnish for Prints — Le Bosse's Hard Var-
nish—Le Dray's Marmorelum — Leeches, Application of

— Lemeris Solvent for Antimony — Lemonade, &c. —
Lemons to Preserve with Sugar, Biscuits, Brandy,
Cakes. Cheese Curd, Concrete Oil of. Cream and Jelly, &c.
Le Mori's Ointment — Lenitive Electuary — Lenses, Cement
for — letters, to Disinfect — Lettuce, Extract of — Levure

— Light Balls — Lightning, to Escape from — Lignum*«
Antiscorbutic Drops — Lilac, to Dye Silk — Lime, Chlo-
ride of — Lime Cylinders, for Oxy-llydrogen Microscopes

— Lime Liniment — Lime Sulphurtt of — Lime Water
— Linctus, or Lohoch — Linen, to Bleach — Liniment •
Linseed Oil, Purifying of. Poultice, and Tea — 1 Jn
Salve — Liqueur de Pressavin — Liquid I'oil for Glass
Globes, Glue, Pounce, &c. &c. .

No. 28. Liquid Soap, Eouge, and True Blue —
Liquoililla — Liquor Ammoniaj, and Potassas- Liquorice
I.,ozenges, Extract of. Juice, ani to llefine — Lisbon Diet
Drink, and Wine — Litharge, and Plaister — Lithographic
Chalk. Ink. Transfer Ink, Transfer Paper — Litmus, and
Paper — Liver of Sulphur, and of .\ntimony — Locatelli's
Balsam — Lockyer's Pills — Logwood, Kxtract of — Lohoch

— London's Patent Solid Salt — London Ale — Lord Mayor's
Cake — Lotion — Lovage Cordial — Lowitz's Acetic Acid —
Lozenges — Lucifer Matches— Ludolph's IMagistery of
Opium — Lugol's Solution of Iodine — Lumbago — Lunar
Caustic — Lundy foot's Sniifl" — Luting for B..ltles— Lutes
for joining Apparatus — Lymingion Salt — Lynch's Embro-
cation— Macaroons — Macaron, Creme de — Macaroni —
Mace Ointment — Macquer's Acid Soap, Arsenical Salt —
Madden's Vegetable Essence — Madder Lake, and Red to
Dye — Madeira, British — Madeira, to tine — Maggots in
Sheep — Magnes Arsenicalis — Magnesian Drink — Mag-
nesia Lozenges, Mixture of, Water — Magnets, Artificial.

No. 29. Magnets, to preserve — Mahogany-colored
Cement, Imitation of. Stains, Varnish — Mahomed's
Electuary — .Mallan's Succedaneum— Malmsley, British —
!Malt. Extract of. Patent, Poultice, to Make, Vinegar,
to determine the Qualities of — Maltha, or Greek Mastich
— Mange, Remedies for — Manheim Gold — Manna Linctus
and Lozenges — Maple, to Imitate — Maraschino de Lara,
French — Marble. Imitative, to Stain, to Clean — Marbled
Soap Balls— Marbling the Edges of 13ooks, the Covers of
Books — Marechaie,Eau de — Marechal Hair Powder, and
Pomatum — Marine Glue and Soap — Marking Ink for
Linen — Marking Linen, New mode of — Marlborough
Cakes — Marmalade— Marriott's Dry Vomit — Marsden's
Anti-Scorbutic Drops— Marseilles Vinegar — Marshall's
Mixed Oils, and Cerate — Marsh- Mallows, Decoction of.
Fomentation, Lozenges, Paste, and Syrup of — Martin's
Varnish — Massicot — Mastic (iallipot Varnish, Mortar —
Mastic Varnish Compound and Camphorated — Mastica-
tories — Mathieu's Vermifuge — Matthews' Injection for
Piles — Matthews' Pills — M auger s Varnish — Mead.

No. 30. Mead Wine — Measles, &c. — Mecca, Balm
of — Mechi's Razor Paste — Medallions, &€ — Megilph —
Melons, to preserve — Mercurial Balls for Horses, &c. —
Mercury, Honey of, to Purify — Merangues — Metallic
Paper — Metals, Cement for — Meteoric Iron — Metheglin —
Mezereon Ointment — Microscope — Microscopic Objects —
Mildew in Wheat, &c. — Military Fever — Milk. &c —
Mille Fleurs, Eau de. Ices — Mince Cake, &c. — Minde-
rerus, Spirit of — Mineral Chameleon, Marmorelum, &c.

No. 31. Minium and Mineral Orange — Mint, Infusion
of. Mint Water— .Mixed Fruit Wine— Mixed Oils— Mock
Gold — Modelling Wax— Moire Metallique — Mole, to Dis-
perse— Monicon, or Damonicon — Montpellier Yellow —
Mordants for Dyeing — Morella Cherry Syrup, and Wine
— r>lorocco Leather — .Morphia, Syrup of — Morison's Pills
— Mortar, to Make — Morveau's Preservative Phial, W.hile
— Mosaic Gold — Mottes (de la) Golden Drops — Moulds.
Elastic, &c. — Mountain Wine — Mouih or Indian Glue.
Modelling Wax for — Muffins — Mulberry Syrup, and Wine
— Multum — Mum— Mummy Brown — Mumps — Munro's
Cough Medicine — Muriatic Acid Gargle — MuscadelWine
— Mushroom Ketchup, &c. — Musk, Artificial, &.c. — Mus-
tard Electuary of, &c. — Mynsicht's Elixir of Vitriol —
Myrrh, Gargle of. &c. — Myrtle Water — Nankeen Dye —
Naplie, Kau de — Naples Biscuit and Yellow — Najjoleon's
Pills — To Preserve Objects of Natural History — Narcotics
— Nectar — Neroli, Essence of. Wash Balls— Nervine Oint-
ment—Nervous Cordial— Nettles, Sting of— Neutral Tint
— Newman's Opium — Newmarket Oil — Night-Mare —
Nine Oils — Nipples, Chapped, to Heal.

CONTENTS OF THE NUMBERS OF THE

DICTIONAIIY OF PRACTICAL RECEIPTS,

Contents of No. 32. Nitre. Gargle of— Nitre
Linclus of--Xitre LK>zenges— Nivernoise Sauce— Non-
pareil Saiice->"Norfolk Leather Preserver — Norris's Drops
—Norwich Biscuits— Nosegay. Essence of— Nottingham
Ale— NoiitHeur's Cure for Wi.rms— Novargent— Noyeau
— Noyeau Crenie de — >'uirs Sauce — Nutmeg Corili il —
NutBieg. Kssence of— Nutmeg. Spirit of— Nutmeg, Syrup
of- NuxVomica, Extract .if— Nux Vomica Liniment of—
Nux Vomica. Tincture of— Oak Bark. Garble of— Oak.
Graining of— Oak Varnish— Ochres— Odontalgic— Odon-
talgic Drops— Odontalgic Tincture— Oil ColorCakes- Oil,
t(. take from Boards— Oil Varnish— Olibanum. Compound
.Mixture of— OiibaTiuin. Electuary of— Oliver Biscuits-
Onion's Fusible Metal— Onions to Pickle— Ophthalmia

— Ophthalmic Ointment — Opiate. .Anti-Tubercular —
Opiate Confection- Opiate en Puudre— Opiate Mixture-
Opiate, or Thebaic Pills- Opium Cerate— Opium Ex-
tract of — Oj>ium LoAenges— Opium Ointment — Oi)ium
Pills — Opium Plai^ter — Opium, Syrup of — Opium, Tinc-
ture of— Opium, Vineuar of — Opodeldoc— Optician's
Cement— Orangeade — Orant-e Brandy— Orange Cordial
—Orange Cream— Orange Cr.-me d' — Orange Flower
Powder -Orange Flower Kalafia— Orange Flower Soap —
Orange Flower Water— Orange Juice. Syrup of— Orange
Lake— Orange Marmalade— Orange Peel. Infusion of—
Orange Peel Ratafia— Orange Peel. Syrup of— Orange
Peel, to Candy— Orange Peel Water — Orange Pomatum
—Orange PulTs— Orange Tarts— Orange Wine— Orfila"s
Ilair Dye— Orgeat Paste— Orpiment—Ofria Loxenges—
Orris Perfume— Ottar of Eoses— Oxalic Acid, to Detect
— Oxycroceum, &c. &c.

. No. 33. Oxley's Tincture for Tooth-ache— Oxyge-
nized Lard— Oxymel— Oyster Ketchup — Oyster-Shell
Powder — Paint. Flexible — I'aint. to Remove theSmell of
— Painter's Cream — Panada — Paper Bleaching — Paper
Glazing of— Paper Paste— Paper Powder, or Pollen
Powder — Paper, Staining of. Yellow, Crimson, Green,
Orange, Purple — Papier de Surete — Papier Mach»§e —
Paracelsus's Plaister— Parchment— Parchment Glue—
Paregoric Elixir — Pareira Infusion of— Parfait Amour—
Paris's Test for Wine.&c— Parisian Dentrifice — Parisian
Soft Varnish— Parkers Cement— Parliament Cakes—
Parmentier's Salad Vinegar— Parmesan, to imitate —
Parolic, or Universal Cement — Parsnip Wine — Passover
Cakes — Paste for Book- Binders, 4ic.—Pastiles— Pat-
chouli. Essence of— Patent Cement— Patent Ink— Patent
Mustard — Patent Yellow — t'auline Confection — Pavilion
Cakes — Payen's Alcohol — Peaih Blossoms. Syrup of—
Pearl Powder— Pearl Soft So«»p— Pearl Water— Pearls,
Discolored, to Whiten— Pears, to Dry— Pears to Pre-
serve—Poclorals-Pencil Drawings, to Preserve— Penny-
royal, Essenceof — Pennyroyal Water — Pepper. Electuary
of — Pepper Salve — Pepper, Tincture of — Perpermint
Cordial — Peppermint Drops — Peppermint. Essence of —
Peppermint Lozenges — Peppermint, Oil of — Peppermint.
Spirit of — Peppermint Water — Percussion Caps, Priming
for — Perfume for Scent Boxes — Permanent White — Per-
petual Ink — Perry — Persian Cream — Peruvian Balsam,
Emulsion of — Peter's Pills— Pew's Cement — Pewter.

No. 34.. Phial Glass— Phosphoric Alcohol— Phos-
phoric Ether — Phosphoric Oil — Phosphoric Writing —
Phosphorus Bottles — Phosphuret of Sulphur — Photogra-
phic Paper — Daguerre's Ueceipt — Golding Bird's Receipt
—Photogenic Drawings, to make — Photogenic. Drawings,
to fix — Piccalilli, or Indian Pickle — Picromel — Picture
Frames, Gilding of — Pictures, to Clean — Picture Varnish

— Pierre Divine — Piles, or Hoemorroids, (Three Receipts)
— Pimento, Spirit or 1 incture of — Pinchbeck — Pine-
apple Ice, (Four Receipts) — Pink Saucers. Pink Dye —
Pinks. Syrup of — Pin Wheels— Pistachio Cream — Pitch
Ointment, (Two Receipts)— Pit Coal Black— Pith Balls,
for Electrical Uses — Plague Water — Plaster of Paris, to
Cast in. (Two Receipts)— Plaster Casts. Polishing of,
(Three Receipts) — Plaster Figures, Bronzing of — Plate
Glass, Composition of (Two Receipts)— Plate Powder,
(Three Receipts) — Plated Articles, to Clean — Platinize,
Metal Goods to — Platinum Moir. or Spongy Platinum —
Platinum Ointment — Pliable Varnish for Umbrellas —
Plombiere Ice, or Swiss Puddings — Plunket's Ointment
for Cancer — I'lunkefs Ointment — Plums, to Preserve —
Plummer's Cement — Plummer's Pills — Plummer's Pow-
der— Pollard Oak — Polychrestum, Elixir of — Pomambra,
or Sweet Balls, (Two Receipts) — Pomatum, (Four Re-
ceipts)— Pomatum, Scents for. (Six Receipts) — Pongibou
Snuff- Pontefract Lozenges — PontifTs Sauce— Poplar
Buds Ointment— Poppy Lozenges— Poppy Oil, to Dry, 8tc.

No. 35. Poppies. Syrup of — Poppies, Tincture of —
Porcelain, or China — Porcelain. Enamels for — Porcelain,
Colors for — Port Wine, Imitative — Port Wine, to Fine —
Port Wine, to Improve — Portable Glue — Portable Soup
— Porter, to Brew. (Three Receipts)— Port Fires — Port-
land Powder, for Gout — Poriu»>al Water — Portugal Cake-
Potatoes, to Preserve— Potatoes, I'rosted, to lise — Po-
tatoe Bread — Potatoe Jelly — Potatoe Paste — Pot Pourri —
Pots des Brins — Pounce, (Three H^-ceiptrt) — Pound Cake,
(Four Receipts)— Powell sDinreiic Drops— Powell's Bal-
sam—Pradier's Poultice f.ir ihe Gout — Precipitate Oint-
ment, White Red. — Presburg Z veiback. or Biscuits —
Pricked British Wine*, to Restore — Prince Rupert's
Drop.s — Princes Cordial — Printers" Ink. (Fi ur ReceipU<)
— Printing Inks, Colors for. Red, Blue. Green. Brown,
Lilac. Lilac Pink. Oranije and Black — Printers" Rollers
— Printers' Types— Prints, to Bleach — Prints, to Copy.
(Five Receipts) — Prints, to Transfer to Wooil — Prints,
to Size before coloring — Prints. Varnishes for Colored,
(Three Receipts) — Primrose Vinegar — P^metheau
Light Boxes. &c. &c.

No. 36. Propiiety, Elixir of — Prunella. Salt of—
Prussian Blue, (ThreeReceipts)— Prussian Cakes— Prus-
sian Green, (Two Receipts) — Prussic .Acid Lotion,
(Three Receipts) Prussic .\cid Mixture — Punch, (Four
Receipts) — Punch a la Romaine — Pun<h-waler Ice —
Purging Medicines, (Six Receipts) — Purging Mixture —
Purging balls for Horses, (Two Receipts) — Purl, ('l'v\o
Receipis) — Purple Knamel — Purple Fire, (Four Re. cipt-.)
— Purple Precipitate of Cassius —Purple Tableltes —
Putty for Glaziers, Flexible — Pirola, Infusion of— Pyro-
ligneous Acid, or Wood Vinegar — Pyro|>hori, (Two Re-
ceipts)— Quass — Quassia, Extract of— Quassia, Infusion
of — Queen Cake — Queen's Cordial — Queen^ Metal —
Queen's Y'ellow — Quick Match — Quicksilver Ointment.
(Two Receipts) — Quills, Preparation of. (Four Receipts.
Dutch Method, French Method. English Method. Aus-
trian Method) — Qumce Marmalade — Qumce Wine —
Quinine. Medicines, viz. Cerate, Essence, Lozenges. Oint-
ment, Wine, and Syrup — Quin's Sauce, (Two Receipis)
— Ragout Spice — Raisin Vinegar— Raisin Wine — Rasp-
berries, to Preserve whole — Raspberry Cordial or Brandy
— Raspberry Cream — Raspberry Drops — Raspl)erry lee
— Raspberry Jam — Raspberry Jelly — Raspberry Paste
— Raspberry Rock — Raspberry Syrui) — Raspberry Vine-
gar Syrup- (Two Receipts) — Raspberry Wine. (Two
Receipts; — Ratafia, Red. Dry Sharp, and Common —
Ratafia Cakes — Ratafia, Essence of, Aic. &c.

No. 37. Ratcliffe's Cough Mixture— Razor Paste
— Red Chalk Crayons — Red Crockery, Glaze for, Dyei.
Enamel, Red Ink, Lead, and Stains for Gla.ss— Reece s
Remedy lor Flatulence — Refrigerant .Medicines — Regency
Buns — Rembrant's Etching Varnish — Rennet Whey —
Resin Cerate, (Yellow Basilicon) — Resin Buiibles, Rey-
nolds's Specific for Gout. flic. — Rhatany, Extract of —
Rhatany Root, Tincture of — Rheumatism — Rhodium,
Oil of— Rhubarb, to distinguish good from bad — Rhubarb,
Extract of — Rhubarb. Infusion of — Rhubarb. Mixture —
Rhubarb Pills — Rhubarb Powder— Rhubarb, Tincture
of, and Rhubarb Wine — Rice Biscuits — Rice Cakes —
Rice Glue— Rich Plum Cake— Rich Seed Cake— Riga
Balsam — Ring Gold — Ringwood Ale — Ringworm — Ro-
chelle Salt — Roche's Embrocation for Hooping Cough —
Rockets, Compositions for Filling, Rains for. Stars. Sticks,
length of — Rock-work and Reservoirs, Cement for —
Roman Candles, Roman Cement, &c. &c.

No. 38. RoseatePowder— Rose Cerate-Lip Salve
— Rose Hair Powder — Rose Lozenges — Rose Oil for the
Hair — Rose Drops — Rose Pearls — Ro.se Pink — Rose Soap
Rose Water, and Rose Wine — Rose's Glaze for Earthen-
ware— Roses, Conserve of, Essence of. Honey of. Infusion
of, 8c Linctus of — Rosemary. Oil of. Essence of. and Water
— Rosewood, to Imitate— Rouge — Rout Cakes. Biscuits —
Rousseau's Drops — Rowland's Kalydor. Macassar Oil —
Royal Essence — Ruby, to Imitate — Rudius's Pills — Rue,
Confection of. Ointment — Rufus's Pills— Rum Shrub —
Rusks — Ruspini's Tooth-powder, Tincture for the I'eeth
— Rymer's Cardiac Tincture — Sack Wine. Imitation of —
Sitffron, Tincture of — Sage Wine — Sailor's Flip — Salberg
Wash — Saline Draught — Saloop — Samphire to Pickle —
Sandarac Varnish — Sap Green, Preparation of — Saraapa-
rilla. Decoction of — Satins and Sarsenets, White, to Clean
— Savoy Cake.s — Saxon Blue — Scald Head Ointment —
Scarborough Water Cake.s — Scamniony, Electuary of —
Scarlet to Dye Cloth — Scarlet Fever — Scent Powder —
Scheele's Green — Scheele's Prussic .\cid — Scotch Ale. &c.

CONTENTS OF THE NUMBERS OF THE

DICTIONARY OF PRACTICAL RECEIPTS

No. 39. Sootfh Buns, Cream, Marmalade, Salt,
Seed Cakes, Short Bread — Scott's Pills — Scouring Drops
— Scrofula — Scrophularia Ointment — Scudaniore's Gout
Lotion — Sculptors" Vlodels. Composition foir — Scurvy-
grass, Conserve of, Spirit of — Seal Engravers' Cement —
Sealing Wax— Seals, to take Wax Impressions from —
Sea Sickness — Sedatives — Sedative Mixture— Seed Bis-
cuits— Seeds, Packing Garden — Seidlitz Powders, Water
— Selt/.er Water — Selvvay's Essence of Senna — Semolina
— Senega, Infusion of — Senna, Electuary of — Senna, Infu-
sion of. Simple, Compound, and Tartarized — Senna Mix-
ture, (Black Draught) — Senna Powder, (Batley's Green)
— Senna, Tincture of, Compound — Sepia — Serpentary,
Infusion of — Serpentary, Tincture of — Shaving Oil —
Shaving Paste — Sheep-skin Rugs — Sheldrake's Oil —
Shells, Mending and Cleaning of — Sherbet — Sherry to
to Fine a Butt of— Sherry, to Improve — Ship Biscuits --
Shoemakers' Black— Short Bread — Shot Metal— Shrews-
bury Cakes — Shrub — Silk. Bleaching of— Silk, to Clean
—Silk, to take Stains from — Silkworm Gut— Sillabub —
Silver Coin of Britain — Silver Frosted or Matt — Silver
Tree, to prepare — Silvering Copper Ingots — Silvering
Powder — Simple Cerate — Simple Ointment — Singleton's
Golden Ointment— Size, (Soft Glue) — Size for Artists —
Skeletons, preparation of — Sloes, Conserve of — Slov?
Match — Small-pox, inc. &c.

No. AO. Sniellnme's Eye Ointment — Smith's Solder
for Tin — Smoke, Essence of— Smut in Wheat, to prevent
— Soap Cerate, Enema or Injection. Essence of, Linctus.
Liniment, Liquid — Soda Cakes, Lozenges, Powders, Water
in Bottles — Soft Toilet Soaps — Solders, viz. Common or
Tinman's. Soft, for Steel Joints, Silver for Jewellers,
Silver for Plating, Gold. Plumber's, Glazier's, Pewterer's,
Hard. Fine, Fusible — Brass Solder for Iron, Copper-
smiths, &c. — Solomon's Balm of Gilead — Sore Throat
(Sev«>n Keceipts, Common, Putrid. Inflammatory. Ulce-
rated. Gargle, &c.) — Soy, English — Spearmint, Essence
of — Specula Metal — Speediman's Pills — Spermaceti, to
Refine— Spermaceti Cerate or Ointment, (Two Receipts)
Spermaceti Linctus — Spielmann's Eye Ointment— Spike,
Oil of. Imitative — Spilsbury's Anti-Scorbutic Drops —
Spirit Varnish — Spirituous Lotion — Spitting of Blood, to
Prevent — Sponge, Bleaching of — Sponge Biscuits — Sponge
Cake — Sponge Lozenges — Sportsman's Cordial — Sprains
— Sprats, Essence of — Spruce Beer — Spruce Beer
Powders — Spruce, Essence of — Squibs or Serpents —
Squill Mixture — Squill Pills — Squills, Conserve of -
Squills. Honey of — Squills. Linctus of — Squills, Oxymel
I of — Squills. Syrup of — Squills, Tincture of — Squills,
I Vinegar of — Squires Elixir — Standard Measures. -Vlloy
for — Starch, Sugar from — Starch Lozenges — Siarch
Manufacture of — Starkey's Pills — Starkey's Soap —
Stavesacre Oin'ment — Steel Lozenges — Steel and Plati-
num, Alloy for — Steel to Color Blue— Steel, to distinguish
from Iron— Steel, to Gild — Steel Goods, to preserve from
Rusl, &c. &c.

No. 4-1 . Steel Mixture, (Three Receipts)- Steeis's
Opodeldoc — Steinacher's Nitric Acid — Stephens's
Remedy for the Stone — Stereotype Plates. Alloy for —
Sterrys Plaister — Stimulant Enema — Stimulant Lini-
ment— Stimulant Mixture — Stimulant Pla'.ster — Stoerck's
Pills — Stomachic Draught — S'oiiiacliic Electuary — Sto-
machic Elixir — Stomachic Tincture — Stomachic Wine —
Stopping-out Varnish — Storax Pills — Storey's Worm
Cakes — Storm Glass for foretelling the Weather —
Stoughton's Elixir — Strains, Embrocation for — Stramo-
nium Lincture of — Stramonium Ointment — Stranguary.
Treatment of — Strawberry Jam — Strawberry Wine —
Straw Bleaching — Stiuve's Lotion for Hooping Cough —
Strychnine Mixture — Strychnine Pills — Strychnine Spirit
of — Styptics — Styes in the Eye-lids. Treatment of — St.
Yve's Eye Ointment — Succedaneum. Mineral — Sugar
to Boil and Clarify — Sugar Candy — Sugar Rock — Sugar
Vinegar — Sulphate of Zinc Ointment — Sulphur, Balsam
of— Sulphur Bleaching by — Sulphur Coins, to make —
Sulphur, Electuary oi. Simple, and Compound — Sulphur
Lozenges — Sulphur. Milk of — Sulphur Moulds for Medal-
lions, &c. — Sulphur Ointment — Sulphur, Precipitated
Milk of — Sulphur Seals. Medals, Coins, &c. — Snlphur,
Tincture of — Sulphur, to obtain Pure — Sulphuret of
Mercury Cerate — Sulphuric Acid Ointment — Suppository.
Purgative, Sedative and for Worms — Swinton's Daffy's
Elixir — Sydenham's Lenitive — Sympathetic Inks. viz.
Black, (Two), Brown, Blue, Yellow, Red — Syrian (farnet.
to Imitate — Syrup Cream, or Cream Syrup — Table Ale—

, Table Beer— Tain, Eau de, (Thyme Water)— Talc Water
I —Talc. Oil of —Tamarinds, Conserve of — Tamarinds
and Senna — Tannin Ointment— Tar Ointment — Tar Var-
nish—Tar Water— Tartar Emetic— Tartar Emetic Mix-
ture—Tartar Soluble — Tartar, Soluble Cream of—
Taylor's Defensor, &c. &c.

No. 42. Taylor's Mixed Oils— Taylor's Red
Bottle— Taylor's Remedy for Deafness— Tears of the
Widow of Malabar— Terra Cotta— Terra Japonica. Tinc-
ture of— Terra Sienna — Terro-Metallicum. for filling
Decayed Teeth— Thibaut's Balsam, to Heal Cuts and
Wounds, and stop Bleeding — Thieves' Vinegar— Tin.
Crystalized— Tin, to Coat with Bismuth— Tin Mordants
—Tin Powder— Tin Tree, to Prepare— Tinning Pins and
Tacks — Tipsy Cakes — Tobacco, British Herb — Tobacco
Ointment — Tobacco, Enema of— Tolu Loaenges — Tolu
Tincture of— Tomato Sauce— Tombac, Red and White
— Tonic Medicines, (Nine Receipts)— Toothache Drops
(Eight Ditto)— Tooth Powder, (Eight Ditto)— Topaz, to
Imitate the— Tortoise-shell. Joining of— Tortoise-Shell
Boxes — Touch Paper— Tourney Cement — Tracing Papers
(Nine Receipts) — Tragacanth, Compound Powder of —
Transparent Soaps — Treacle Beer — TreacU, to make
Brandy from — Tripharmlc Ointment— Trotter Oil, to
Purify— Tunisian Cement —Turkish Bloom— Turkish
Depilatory — Turlington's Balsam — Turners' Cerate for
Chilblains- Turners Work, Polish for— Turpentine Bal-
sam of — Turpentine, Enema of— Turpentine, Linctus of —
Turpentine Liniments for Rhumalism, Lumbago, &c. —
Turpentine Mixture— Turpentine Varnish— Tutania. or
Britannia Metal. German, and Spanish- Type Metal.
Small — Typhus Fever- Ultramarine— Ultramarine Arti-
ficial—Usquebaugh—Valerian Mixture— Valerian. Tinc-
ture of— Vancouver's Cement — Vandyke Brown — Vanilla
Cream — Vanilla, Essence of — Vanilla Lozenges — Varnish
—Varnish, to Polish— Varnishes, Colors for, viz. Black.
Yellow. Blues. Greens. Reds, Purples, Brick Red. Buff.
Violet, Pearl Grey, and Flaxen Grey — Vauquelin's
Tincture 'of Spirit of Turpentine — Velno's Vegetable
Syrup — Velvet. Satin, Silk, &c. Colors for Painfng on.

No. 4.3. Velvet. &c.. Color* for Painting on— Venus,
Huile de — Veratrine, Liniment— Veratrine Ointment —
Verdigris— Verdigris. Liniment of. Ointment, Plaister—
Verditer. Blue — Verjuice Water for Iceing — Vernii-
celli— Vermifuge, or Worm Mixtures— Vermillion— Ver-
vain's Balsam— Vidonia Wine, to Fine— Viganis' Elixir
of Vitriol — Vinaigre Dentifrique, Cosmestiques — Vinegar,
to make. Ointment— Violet Powder, Perfume, Syrup of
— Vitriolic Elixir — Vitriol, Sweet Spirits of — Wafers,
Manufacture of— Wafers, (in Cookery) VValker's Jesuit's
Drops—Walls, to preserve from Dampness — Walnuts to
Bleai-h. Extract of, to Pickle, Ketchup — Want's Powder
— Ward's Antimonial Pills. Essence for Head-Ache,
Paste for the Piles. Sweating Powders. White Drops —
Ware's Golden Ointment — Warner's Cordial — Warming
Plaister— Warts— Wash Balls— Wa.ip, on Swallowing a
— Watchmakers'Oil — Water Cement — Water Color Cakes
— Waterloo Crackers— Water-proof Boots, Cloth— Wax,
Bleaching and Purifying of. Imitations of. Candles. Imi-
tative Lute or Cement. Ointment — Webster's Antibilious
Pills, Diet Drink— Wedel's Oil — Wedgewood Composition
of Mortars— Weeds, Extirpating— Welsh Ale— Weld Yel-
low— WestphalianEsseiice of Wood Smoke— Whipt Cream
—White Briony, Extract of. Camphorated Ointment,
Enamel, Hellebore, Extract of, Lotion or Wash, Metal,
Precipitate, Precipitate Ointment— Whitlow — Whortle-
berry Mixture — Whyte's Tincture of Bark — Wigg Cakes
— William's Stucco — Wilson's Prepared Asphaltum —
Windsor Ale, Soap — Wine Bitters — Wines, to Fine or
Clarify, to Correct when Harsh, to Correct when Acid,
to Clear Foul or Ropy — Wine Vinegar— Wood Staining.

No. 44. Wool Bleaching — Worms — Wormwood,
Conserve, Extract, and Essence of — Writing Fluids —
Wych's Stucco — Yeast, to Preserve, Substitutes for,
and Poultice — Yellow Dipping Metal. Dyes. Ink, Lotion
or Wash, Resin Soap, and Stain for Glass— Yolk of Egg
Ointment — Yorkshire Oat Ale — Youngs Purging Drink —
Zftfifreand Smalts— Zincing — Zinc Labels, Ink for Writing
on — Zinc Lozenges — Zinc Ointment — Title, Preface,
Introduction, Tables of Weights, &c. &c

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Date Due

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L.brary Bureau Cat. No 1137

QC51].n

bim

3 5002 00134 1689

Francis, George William.

Electrical experiments; illustrating the

PMYSIC-

QC

517

F7

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