rrnts,;

mm,-

#\,

'^S^

uJ-.-^

te9-§

r-r-

^^m3^ ^'

,# %

ELECTRIC PHENOMENA.

BY

D-^ J. Rosenthal.

BERLIN 1872.

C. G. LUDERITZ'sche Verlagsbuchhandlung.

CARL HABEL.

33 Wilhelm Strasse 33.

LONDON, NEW-YORK,

WILLIAMS & NORGATE ^' WESTERMANN & Co.

GERMAN AND FOREIGN BOOKSELLERS
14 Henrietta Street, Covent Garden. 524 Broadway.

^<*|^

Libra/ry,

J. HE greater the progress, wliicli Natural History makes in
the knowledge of facts and their inner coherence, the more
easy it is to understand those causes which lay the founda-
tion of the facts. Whilst formerly, as an explanation for al-
most every phenominal appearance, the existence of its own
peculiar substance was admitted (for example "Caloric", which
was considered as imponderous, or, still earHer, that so-caUed
"Phlogiston", which is supposed to contain such a negative
weight, that through its existence the other bodies which are
connected with it, become much lighter) ; we now attain, more
and more, the knowledge, that every phenomenon of Nature
is to be traced back to the motions of the smallest particles
of which all matter is composed.

The phenomena on which I intend to discourse, are very
remote from this notion. However minutely they may have
been investigated separately, and whatever great results they
may have led to in a practical sense, in order to explain them
fully, it is necessary for us to make an assumption ("hypo-
thesis" as it is called by men of science), for the accuracy of
which we have no proof, and it is only devised for the pur-
pose of concentrating the whole series of phenomena into a
general point of view. The value of such suppositions con-

1872. IL 1. (125) A3

4 Quarterly German Magazine,

sists principally in their use as a medium of instruction, and
they can be abandoned as soon as they evince themselves as
inefficient, or we can find more simple and therefore better
ones.

According to the supposition in question, there are two
highly subtile, imponderable and elastic fluids, which are so
refined, that we are not able to weigh them in the most ac-
curate scales, but infer their existence from their effects.
These fluids are called positive and negative electricity. Each
has the quality to repel that body, which is impregnated with
its own identical fluid, and on the other hand, to attract that 9
which possesses the opposite, and this attraction and repulsion
take place in inverse ratio to the quadrat of the distance from
one another; i. e., if two electrical fluids are twice or three
times as far from one another, then their repulsive or attrac-
tive influence is only of one fourth or one ninth of the power
it would be, were a simple distance between them.

These two fluids always exist, where solid substance is
to be found, they cling to the smallest particles of matter, but
nevertheless they are capable of passing from one molecule
to the other in one and the same body, as well as from one
body to another. Generally these two fluids are present in
equal quantities in aU bodies, and the result thereof is, that
they cannot exercise any sensible influence outwards. We
then caU the bodies neutral-electric or non-electric. When,
however, in a body one of the fluids is found in a larger
quantity than the other, its stronger effect asserts itself and
we call the body electric and indeed positive-electric^ if the
positive fluid exists in excess, and negative-electric^ if the ne-
gative fluid preponderates.

Among the means, which effect such an unequal distri-

(126;

On Electric Phenomena. 5

Tbution of electric fluid, friction takes the first place. If we
rub a stick of sealing-wax witli a piece of woollen cloth, and
then touch with the sealing-wax a light little ball made of
the pith of the elder-tree and suspended by a silken-thread,
we shall find, that the ball is at first attracted by the sealing-
wax, but as soon as it conies in contact with it, it is quickly
repelled. It is evident, that this last repulsion can only be
caused by the fact, that the stick of sealing-wax has imparted
to the baU a small part of that electricity, which has been
excited by friction, and that now the state of electricity in
the sealing-wax and the little ball being similar, they reci-
procally repulse each other. As the ball is very light and
hangs quite free, the electric fluid carries with it the material
particles to which it adheres, and thus, the repulsion, which
takes place between the invisible electric fluids becomes per-
ceptible to us through the movement of the visible substance.
If we now rub a piece of glass and touch with it a
second ball hung up in a similar manner, and of the same
kind as the before-mentioned, we attain just the same result.
The piece of glass becomes electric through friction; it also
imparts to the baU through contact a portion of its electricity
and the electricity of a similar kind contained in the glass
and the ball, repulse one another. If we now bring the piece
of glass in contact with the ball, which was first touched with
the sealing-wax, it wiU be attracted by it, and likewise, the
ball, which was first touched by the piece of glass, will be
attracted by the seaHng-wax. "We conclude therefrom, that
the electricity, which was excited in the glass and the sealing-
wax, are of a different kiud, and we call that excited in the
glass positive or vitreous electricity^ and that in the sealing-
wax, negative or resinous electricity. Indeed, the electricity

(127)

6 Quarterly German Magazine.'

of all resins is (like sealing-wax) negative, when excited by-
friction; and this phenomenon was first remarked in Amber.,
which belongs also to these resinous substances and the whole
series of phenomena is called electricity from the Grecian name
for amber (Elektron).

If we bring the two balls together, the one which had
been touched by the glass and the other by the sealing-wax,
they will attract each other equally, as they are laden withj
electricity of a similar kind; but at the moment of colHsioi
they fall away from one another, and prove themselves
non-electric. The two opposite states of electricity have united
themselves and the balls contain again both electricities in
equal quantities und are therefore non-electric.

We win now rub against each other a piece of glass and
a piece of ribbon which is tightly stretched out, and then
touch the two balls, which have become non-electric, the one
with the piece of glass, the other wi\h the piece of ribbon.
Both appear again electric, and indeed, the ball touched by
the glass will be repelled, while, on the other hand, it will
be attracted by the ribbon. The case is just the contrary
with the other baU. We then see, that both the bodies,
which have been rubbed against one another, have become
electrical, but that both receive an opposite state of electri-
city. This proposition is always valid, when two bodies are
rubbed together, and w^e leam from it, that no electricity can j
he excited by friction^ but that only an ulterior distHbution qf^
both the electric fluids takes jilace, so that in the one a 5wr- •
plus of positive electricity is accumulated^ and in the other of \
negative.

If we rub a rod of metal, which we hold in the hand,
with wool, we cannot prove, that there exists the slightest

(123)

On Electric Phenomena. 7

face of electricity in it. If we, however, fasten the rod to
handle of glass or sealing-wax, or if we WTap the part of
which we take hold in silk, and then rub it, it will become
strongly electrical, and we can observe all the same pheno-
mena which we learned from the piece of glass or the sealiag-
T^ax.

As soon as we touch any part of it with the hand, then
all electricity immediately vanishes from it. If we continue
to rub a piece of sealing-wax or a glass rod at one end, and
then test another part, wliich has not been rubbed, with the
ball of pith, we shall find them quite non-electric. On the
<jontrary, if we rub a metallic rod which is fixed to a handle
of glass, in a certain place, and then test it in any other
part we may choose, it wiU show itself as electrical. The
tw^o bodies, glass and metal, manifest themselves quite dif-
ferently with regard to their relation towards electrical fluids.
p In metals, the electricity excited in one part, conveys it-
-self easily to another, and spreads itseK over the whole body;
in glass, the transition of the electricity finds a resistance;
therefore, the spreading of it takes place very slowly, or not
at all. Metal is therefore called a conductor of electricity;
on the contrary, glass, seahng-wax etc. are non-conductors or
itisidators. The human body is also a conductor. A rod of
metal rubbed with the hand, immediately sends the whole of
its electricity into the ground ; if, on the contrary, the rod is
fastened to a non-conductor, the electricity finds a boundary,
over which it cannot pass, and it remains in the metal ; there-
fore the metal, with which the experiment is made, must be
fastened to a piece of glass or sealing-wax, or hung up by a
silken cord, that is, to use the technical term, insulated. Air
is naturally a non-conductor, or else, through it all electricity

(129)

8 Quarterly German Magazine.

"would immediately escape; but that is only, wlien it is dry,
as in damp air all bodies quickly lose all their electricity.
This is the reason, why in auditories, where so much humi-
dity is mixed with the air, in consequence of the number of
human beings collected together, and the quantity of burning
lights, it is so difficult to make electrical experiments.

The electrical particles repel each other, through the
swiftness of their motion within the conducting substances,,
tiU they arrive at the surface, where they can proceed no-
further, in consequence of the air, which is a non-conductor.
Therefore all the electricity immanent in the conductor, col-
lects itself on the surface, and forms there a thin layer.
The greater the quantity of electricity accumulated in a body,
the thicker is the layer, and the stronger the power, with
which the repulsed particles strive to reach the exterior. This
is called electric tension. Is the tension very great, the elec-
tricity escapes, in spite of the resistance of the surrounding
air. Therefore every body can only be charged with electri-
city to a certain extent, which must depend on the nature of
tibe body, and that by which it is surrounded.

If for example, a body charged with positive electricity
approaches another insulated conductor, then the free elec-
tricity of the former attracts the opposite state of electricity
in the latter and repulses that which is of a similar kind ta
its own. The ingredients of the neutral electricity of the
second body will, therefore, be decomposed through the in-
fluence of the electricity of the first body, the positive elec-
tricity accumulates ia the end which is averted from the first
body, and the negative in that, which is turned towards it. If
we remove the bodies from one another, then the decomposed
electricities of the second body unite again, and the body be-

(180)

On Electric Phenomena. 9

comes non-electric. If we touch the second body with the
finger during the time it is under the influence of the first,
then the positive electricity escapes into the ground, the ne-
gative, on the contrary, which is bound (or as it is technically
expressed "latent") by the first body, cannot escape. If we
break off the connection with the ground, and remove both
bodies from one another, than the second, through the in-
fluence of the first, is charged with electricity, without the
first having lost the least of its own. This is caUed electro-
motion through decomposition.

From the above described process, the second body re-
ceives contiQually the opposite kind of electricity to the first
one. Both kinds can, however, be kept apart. We wiU take
three bodies. A, B, C, of which A is charged with positive
electricity, B and C are non-electric. We will place all three
in a row, but so that B and C touch each other, while A
stands at a short distance from B. Through the positive
electricity of A, the negative electricity which is in the other
two bodies, wiU now be decomposed. The negative electricity
is attracted and accumulates in B, on the other hand, the po-
sitive is repelled and collects in C. If we now remove B and
C a Kttle from one another, then the decomposed electricities
cannot unite again, and B and C are charged through de-
composition. But as soon as we bring them both together,
if it be but for a moment, the electricities unite and they are
both once more non-electric.

From the decomposing power of electricity results a large
number of phenomena, and many apparatuses are constructed
to exemplify them, of which we will mention some of the
most important. First we must remark, that the attraction
of non-electric bodies through electricity can only be produced

,(131)

10 Quarterly German Magazine.

by decomposition. We have observed, by the first experi-
ment, that the sealing-wax, which has been made electric
through friction, attracts the non-electric httle ball of elder-
pith, but as soon as they come in contact with one another,
the ball is repulsed. The negative electric seahng-wax de-
composes the natural electricities of the ball, and attracts the
positive and repels the negative. As now the positive elec-
tricity of the ball is nearer the sealing-wax than the negative,
the attraction of the former preponderates over the repulsion
of the latter, and the ball is drawn towards the sealing-wax.
As soon as they touch each other, the positive electricity of
the little ball unites itself with an equal part of the negative
electricity of the sealing-wax, the ball now retains a surplus
of negative electricity, and is rejDulsed by the sealing-wax.

From similar proceedings originates also the accumula-
tion of larger quantities of electric fluid by means of electrical
machines. A circular plate or cyhnder of glass is turned be-
tween two leather cushions which have been smeared with
Amalgam (that is: a compound of mercury or quicksilver
with another metal), and thereby rendered positive electric,
while the rubbers become negative electric. The negative
electricity of the rubbers is conducted into the ground. The
part of the glass plate or cyhnder, which has become positive
arrives through rotation at a place, where it stands opposite
or very near to a large insulated metallic ball furnished with
spikes, which is called the prime conductor. Through the de-
composing influence of the glass plate, the negative electricity
of the conductor accumulates in the spikes and attains to such
a tension, that it overcomes the resistance of the thin stratum
of air, and unites itself with the positive electricity of the
glass plate.

(189)

On Electric Phenomena. 11

Is the tension of the electricity on the conductor so great,
that it can no longer be held back by the resistance of the
air, then, of course, the conductor cannot absorb any more
electricity, however much may be conveyed to it. If we, how-
ever, place the conductor opposite to another, which is con-
nected with the earth, then the positive electricity of the first
conductor attracts the negative electricity of the second, and
repels the positive, which escapes towards the ground. The
two opposite electricities in the two conductors so attract each
other, that their tension towards the surface is essentially im-
paired, and just on that account we can convey much more
electricity to the first conductor, than it would be possible to
do in any other case. This reciprocal union of the two elec-
tricities — as it is called by natural philosophers — occurs
in its fullest perfection, when the conductors take the form of
large smooth surfaces, which stand very near and parallel to
one another. But to prevent the union of the electricities,
which attract one another, a good insulator is placed between
them, for instance: a glass plate. Thus an apparatus is formed
which is called after its inventor "Franklin's plate"; a sheet
of glass which is covered on both sides with a thin coating
of tin-foil. If the two surfaces are curved, then we have a
Kleist's or Leyden Phial or Jar, a glass phial or jar coated
inside and outside with tin-foil. A metallic rod, having a
knob at the top, is fixed into the mouth of the jar, and is
made to communicate with the inside coating, while the out-
side is placed in communication with the ground. If we es-
tabhsh a communication between the inside and outside coating
of such a jar by means of a conductor, the opposite electri-
cities re-unite themselves, and the jar is discharged. A cur-
rent of electricity flows through the conductor. If we insert

(133)

12 Quarterly German Magazine.

a human body in tlie circuit of the conductor, there follows
a contraction of the muscles, which have been struck by the
fluid and an excitement of the nerves, which is felt as an
electric shock. If we break a part of the electric wire, then
the two electricities can unite with one another through the
air. This union takes place in the form of light and sound.
In the part, which is interrupted, pieces of pasteboard, wood,
glass etc etc., which have been inserted therein, will be
pierced through or shattered to pieces; combustible bodies
will be set on fire, in short, we can observe in a small way
the whole of the phenomenon of hghtning. Indeed, Hghtning
is nothing more than a discharge of electricity from a cloud
positively charged, to the surface of the earth, which is ne-
gatively charged ; or from two clouds which are charged with
opposite states of electricity. The effect of the hghtning con-
ductor is, that the electricity, which is attracted through de-
composition towards the point of the Hghtning conductor, al-
ready unites itseK by a shght tension with the opposite elec-
tricity in the cloud, and thus wards off the vehement dis-
charge.

Mr. Holz, a private gentleman hving in Berlin, has made
an interesting application of the decomposing effect of elec-
tricity in the machine which has taken his name, viz : "Holz's
machine", with the assistance of w^hich very violent electric
shocks can be produced. A pane of glass is provided with
several indentations, in which are fixed pointed spikes from
so-called vegetable parchement. When a small quantity of
electricity is imparted to it by touching it with a glass rod
or something of the same kind, which has been excited by
friction, and then a second plate of glass which stands very
near the first plate, be quickly turned, the electricity in the

(134)

On Electric Phenomena. 13

second plate will be decomposed, the positive and negative
accumulate in different parts of the glass plate, from whence
they are taken up by imbibers and conducted to the inside
and outside coating of a Leyden-jar, through the discharge
of which we can obtain all the before mentioned effects in the
most violent manner.

Friction is not the only means by which the natural
electricity of bodies can be decomposed, contact alone can
operate in the same manner. It is particularly the contact
of metals and fluids, which produces a decomposition of elec-
tricities. If we immerse two different metals, for example, a
plate of zinc and one of copper into a glass, which is filled
with diluted sulphuric acid, the positive electricity goes from
the zinc through the sulphuric acid to the copper, the nega-
tive from the copper through the sulphuric acid to the zinc.
Free positive electricity collects in the protuberating end of
the copper, and free negative electricity accumulates in the
projecting end of the zinc. Such an apparatus as this is
called a galvanic element or a galvanic chain according to the
Italian anatomist Galvani, whom we have to thank for the
first knowledge of this fact, although the most correct expla-
nation was not given by him, but by his renownd countryman
Alessandro Volta.

The prominent metaUic ends of the chain are called its
poles, and indeed the copper end is designated the positive
pole or positive electrode, and the zinc end the negative pole
\or the negative electrode. If we join the poles by a wire,
the opposite electricities are united. But, as the cause of the
decomposition of the natural electricities continues in opera-
tion, viz; the contact of the two metals with the fluid; the

(135)

14 Quarterly German Magazine.

positive electricity flows continually from the copper through
the wire to the zinc and from the zinc through the fluid to
the copper, and inversely, the negative electricity flows con-
tinually from the zinc through the wire to the copper, and
from the copper through the fluid to the zinc. This rotation
of the two electricities in an opposite direction, is called an
electrical current^ and indeed, a 'permanent current^ to distin-
guish it from the currents in the Ley den-jar, in which the
electricities, which have accumulated on the inside and out-
side of the jar, discharge themselves with a shock. In order
to know, in which direction the electricities move, it is ne-
cessary to observe, what metal forms the positive pole. In
one apparatus it is #bpper; from this proceeds positive elec-
tricity, and as necessarily ■ the negative electricity moves in
the opposite direction, we say, the electric current flows from
the copper through the wire to the zinc and from the zinc
through the fluid to the copper.

The quantity of electricity, which is set in motion by
such a contrivance, is very small ; but it can be increased, if
several elements be so united together, that the copper end
of the one be always joined to the zinc end of the other.
This is then called a combined chain ^ compounded from se-
veral elements. In the first element there remains a zinc end
free, and in the last a copper end, which form the poles of
the connected chain. If we join those by a conducting wire,
then the whole of the electricities, which have been free, move-
through it, whereby we obtain very strong electric shocks.

If we then divide the conducting wire, which unites the
poles, into two parts, the current is interrupted, as soon as
those parts are separated by a non-conducting body. By in-
serting different bodies between the wires, we can conduct

(136)

On Electric Phenomena. 15

the current through the same and study its effect. We will
now submit a part of these effects to a more minute investi-
gation.

As you mil already know, there is in Nature a body
which possesses the property of attracting iron; it is called
magnetite or magnetic iron ore. When steel is rubbed with
this magnetic iron, it imbibes the same quality and can then
transfer it to other steel. If we have such a magnet of steel
in the form of a needle which is so placed on a point, that
it can easily be turned round, we observe, that the needle
continually takes a certain direction, whereby the one end
turns towards the North, the other towards the South. If
we now pass the current of the galvanic chain over the needle,
we remark, that the needle leaves its usual place and turns
its North point either towards the East or the West, until it
comes to rest in a fixed position. If w^e interrupt the current,
the needle returns again to its natural situation.

Such a needle can assist us to discern whether an elec-
tric current be present; but if the current be very weak, then
the deviation of the needle is very slight and scarcely per-
ceptible.. It can be made stronger, if w^e let the wire which
conducts the current, pass several times round the needle, by
wdnding the wire on a frame, in the middle of which the
needle can easily turn. That the current may not go dia-
gonally from one coil to another, but reaUy flow through every
coil one after the other, it is necessary to enclose the wire
in an insulated covering. This is effected by spinning silk
over the wire. In tliis case, the effect of the current on the
needle is greatly multiplied; therefore, such an instrument is
called a multiplicator. For greater convenience we can also
bring a hand on the needle, which plays on the outside of

(137)

16 Quarterly German Magazine.

the frame over a partition, and thus points out the position
of the magnetic needle which is in the interior.

If we unite such a multiplicator with the chain, and then
so change the connection, that the current flows in an oppo-
site direction, then we observe, that the needle also in both
cases takes another direction. If we observe this direction
once for all, then the instrument can not only be used as the
advertiser of a current, but it shows us, at the same time,
its duration, and from the degree of deviation we can judge
of the strength of the current.

In the different experiments which I have described, the
closing of the chain was purely metallic. — It only consisted
of the multipHcator-wire and the pole-wire, which led to it.
Now we will unite the latter with two metallic tin plates and
place these parallel to one another in a glass of water. As
water is a very bad conductor of electricity, we will add a
jittle sulphuric acid to it, through which its power of conduc-
tion is immensely improved. The current goes from one plate
through the water to the other. We immediately see a quan-
tity of little bubbles of gas collect on both plates, which rise
to the surface and then are lost. We think we remark, that
the number of bubbles on both plates are not the same; on
the plate which is connected with the positive pole, there ap-
pear fewer than on the other.

To observe this more exactly, we cover each plate with
a funnel filled with water, and catch the developed gas. We
obtain in each funnel a colourless gas, but that which is de-
veloped on the positive plate, only occupies half the space as
the other. We wiU examine the gas of the positive pole more
minutely; it has neither smeU, taste, nor colour; if we bring
a lighted shaving to it, it takes fixe and burns with a bright

(138)

On Electric Phenomena. 17

£ame. Through these properties we can recognize it as that
gas which chemists call Oxygen.^ and which forms one of the
ingredients of water. Now we will test the other gas. It is
also without smell, taste and colour; when a glowing shaving
is brought near it, it takes fire and burns with a feeble blue
flame. Those are the properties, which belong to Hydrogen^
the other ingredient of water. As chemistry teaches us, that
one part of oxygen and two of hydrogen are united in water,
we now perceive, that through the passage of the electric cur-
rent the chemical union of water in its ingredients is decom-
posed and that these ingredients appear in their original form
as aeriform or gaseous bodies. This decomposition is called
electro-chemical or electrolysis.

The two gases which we have obtained from the water
through electrolysis, can be again combined to water. If we,
for example, do not catch them separately but together, by
bringing the two pole-plates into a closely corked vessel, and
conducting through the cork a curved glass tube under a glas
filled with and turned dowTi in quicksilver, we obtain in the
glass a quantity of both sorts of gas in the same state in
which they were in the water. If we now raise the glass
with the closed mouth and bring a flame to the opening, we
hear a violent explosion, and the side of the glass, which
was before quite dry, is now covered with drops of water,
which have been produced from the union of the two gases.
In consequence of the property of this mixture of gas it has
acquired the name of inflammable gas.

Other combined fluids, which conduct the electric current,
are also decomposed by means of this gas, and many of these
decompositions have obtained a great practical importance. If
we dissolve a metallic salt in water, for example, sulphate o£

. 1872. n. 1. (139) B

18 Quarterly German Magazine,

copper, which is a combination of copper, oxygen and sul-
phuric acid, we obtain a blue liquid, which is so decomposed
through the current, that metallic copper secretes at the ne-
gative pole, while oxygen and sulphuric acid show themselves
at the positive pole. The copper encrusts thereby the nega-
tive pole with a layer which perfectly represents it in all its
protuberances and cavities, and which can be taken off after
it has attained a certain opacity. We then have an inverted
impression of the plate at the pole, on which every protuber-
ance is represented by an elevation and cavities by indenta-
tions. This is used to multiply medals and such things; an
impression of the object to be multiphed is taken in wax,
gutta percha and such hke, and then furnished with a con-
ducting cover, which in connection with the negative pole is
exposed to the influence of the electric current. The first im-
pression gives an inverted copy of the original object, a so-
called matrix \ the galvanic impression is, however, a true
imitation of the same.

Corporeal objects, as busts, statues etc. can be copied in
this manner, which is called electro-metallurgy^ or ih.Q galva-
nic plastic art', a form is made over the body, consisting of
single pieces which are then set together, and a solution of
sulphate of copper is poured into the cavities, and then through
-the current the copper is precipitated on to the form.

A second important appHcation of electro-metallurgy is
made in chalcography or the art of engraving on copper. A
great number of impressions cannot be taken from the copper-
plates which are engraved by artists, in consequence of the
phabiUty of their material, as the delicate Hnes suffer through
the pressure of the printing press. That is the reason, that
the first impressions, the so-called "epreuves d'artiste" and

(UO)

On Electric Phenomena. 19

^'avant la lettre" are so much in request. But now tlie plates
Avliich have been engraved by the artist can be several times
galvanically imitated, and a great number of impressions taken
from them, while the original plate remains quite uninjured,
whereby naturally the number of the good impressions is in-
creased, and their price becomes much more reasonable. In
the same manner we deal with forms cut in wood for wood-
engravings.^ or other purposes, in short, with all objects which
are used in great numbers, in the same form, for example,
government seals, forms to press decorations in leather etc.

Another phase of electro-metaUurgy consists in furnishing
objects with a metallic coating in a galvanic manner. Thus

\ ^e can electro-plate all objects by connecting them with the

; -chain of the negative pole, and putting them into a solution
of muriate of gold, silver, or sulphate of iron, and then ex-

\ posing them to the influence of the electric current. Galvanic
steeling is sometimes undertaken with copper-plates, to give
them a greater hardness, and thereby greater power to resist
the pressure of the printing-press. A very thin precipitation
of a metal, which changes into different colours through the
reflection of the hght, is used to decorate bells for the table

\ and other metallic objects.

If we conduct the current of the chain through the above
described vessel, in which the water is decomposed through
two metal plates, while the developed inflammable gas is trans-
ported through a covered glass-tube into a bell, we can mea-
sure the quantity of inflammable gas, which is developed in a
given time. If we put at the same time the multiplicator in
the circuit of the chain, we shaU find, that the quantity of
inflammable gas, which is developed, is so much larger or
smaller, according to the deviation of the magnetic needle.

(141)

20 Quarterly German Magazine.

"We conclude from this, that the decomposing effect of the
current is much more considerable, the more electricity is set
in motion through the chain, or the stronger the current. If
•we observe it for a longer time, we find, that the effect is not
equal. Immediately after the closing of the chain, the de-
composition of the w^ater as well as the deviation of the needle
of the multiplicator is very strong, gradually however, both
become weaker and weaker, and they are at last quite unob-
servable. What is the cause of this diminution in the action
of the chain? It can lie in the chain itself or in the decom-
posing apparatus.

The plates of the decomposing apparatus or the Volta-
meter^ as such an instrument is called, by natural philosophers,
are formed of the same metal, Platina; they are therefore
homogeneous and do not require in the diluted sulphuric acid
any different electrical tension, and if we unite them wdth the
multiplicator, the magnetic needle does noj; de\Tiate in the
least. If w^e, how^ever, let the current of the chaio, mn through
the voltameter, and then unite it with the multiplicator, we
obtain a strong deviation of the magnetic needle, the Yolta-
meter now develops also a current and indeed, this current
takes an opposite direction in the Voltameter, to that wliich
the current in the chain took originally. These homogenial
platina plates of the Voltameter have become through the
flowing of the current through the chain, the poles of a chain^
and give out a current which is called the secondary or po-
larization current. As this current takes the opposite direc-
tion to that of the original current of the chain, it is clear,
that it must weaken it. The cause of this polarization cur-
rent is, however, no other than the developed gas. The oxy-
gen namely, which is secreted in the positive plate, makes it

(142)

On Electric Phenomena. 21

negative, and the hydrogen, which is secreted in the negative
plate, makes that positive ; a platina plate coated wdth oxygen
and one with hydrogen, are no longer homogeneous, but stand
in relation to one another like zinc and copper, they have
different electrical tension and form together a chain.

That which takes place in the Yoltameter, must also
partly take place in the chain. In that, the current goes, as
we have already seen, from the zinc through the diluted sul-
phuric acid to the copper. It there decomposes the water,
the oxygen is parted from the zinc and the hydrogen from
the copper. Now the oxygen is innoxious ; as it has a great
anology to zinc, it forms in connexion with it a chemical
combination which is called oxyde of zinc, and this again
combines itself with the sulphuric acid to sulphuric oxyde of
zinc, or sulphate of zinc, which is dissoluble in water. The
oxygen, which is separated from the copper, occasions by its
strong positiveness a current from the copper to the zinc,
w^hich acts contrary to and weakens the original current. Thus
the chain contains in itself tbe cause of the diminution of its
strength.

There are, however, means to obviate this cause. Da-
nielle an English Natural Philosopher, has specified a remedy,
which simply consists in removing the hydrogen, in the same
proportion as it rises. This is to be done, by surrounding
the copper with a fluid, which has a great chemical relation
to hydrogen. Such a fluid is a solution of sulphate of copper.
The hydrogen, as soon as it is formed, absorbs the oxygen
from the sulphate of copper and forms it into water, the cop-
per is parted from it and covers the plate at the pole with
an equal layer , as we have seen by the electro-metallurgy.
Thus the whole of the hydrogen is removed, and the copper

(143)

22 Quarterly German Magazine.

plate constantly retains a fresh surface. To avoid the sulphate
of copper from touching the zinc, through which it would be
directly decomposed, the space which contains the zinc, is se-
parated from that which holds the copper, by a porous parti-
tion of burnt clay, or a similar substance, and the space for
the zinc is filled with diluted sulphuric acid. The partition
hinders the mixture of the two fluids , while it permits the
movement of the electricity through its pores.

In this manner we have a permanent chain ^ the power
of which can exist for days together, but as the dilution of I
the sulphate of copper continually decomposes, Ave must, from
time to time, renew it; and as the sulphuric acid changes
gradually into sulphate of zinc, that must also be renewed.
The zinc will gradually be quite dissolved, and we learn from
that, that we cannot produce the movements of electricity from
nothing, but only at the expense of the consumed zinc. From
nothing comes nothing.

Besides this DanieU's chain, there are many other per-
manent chains^ of which we antII only name a few. In Grove's
chain, platina takes the place of copper, and stands in smoking
nitric acid (aqua fortis). Nitric acid forms Hkewise with hy-
drogen, water, because it gives it a part of its oxygen, and
retains its nitric acid. The tension between zinc and platina
is much greater, than that between zinc and copper, the chain
is therefore stronger: but the consumption of sulphuric acid
is very expensive, and the vapours which it exhales, are very
deleterious to metallic objects and to the lungs. As platina
is very dear, Bunsen has replaced it by a coal especially pre-
pared for that purpose, which works in the same manner as
platina. For technical purposes as well as for electro-metall-
urgy and telegraphy DanieU's chains are most to be recom-

(144)

I

On Electric Phenomena. 23

mended, particularly in the somewhat altered form, which
Siemens and Halske have given them.

From the two effects of the electrical current, which we
have already observed, the one, the electrolysis, takes place
in the interior of the body which conducts the current; the
other, the deviating effect of the magnetic needle, is carried
out by the current through the air in the distance. Besides
these differant actions the current possesses many more, which
we cannot singly discuss. Thus it heats, for example, all
conductors through which it flows, and this heating can in-
crease to glowTQg, so that we can, with the assistance of a
fitting conductor, make a wire, at a great distance from the
chain, red hot.

This is used to spring mines, and in surgery to disperse
swellings without the loss of blood. If we conduct the cur-
rent of a strong chain through two ends of coal, which touch
each other, and then separate them a little from one another,
small particles of glowing coal will be drawn from one end
over to the other, and w^e obtain a brilliant electrical light^
which is now very much used for illuminations. The most
important effect of the current is, in every case, the magne-
tizing^ of which we will speak more at large, as the whole of
telegraphy is founded upon it.

If we wind a quantity of wire round a rod of soft iron
and conduct through it an electric current, the iron becomes
magnetic and retains this capacity as long as the current lasts;
it is, however, immediately non-magnetic, as soon as the cur-
rent is interrupted. In this manner it is possible for us to
procure a magnet or load-stone, and then again to transform
it into an ineffective piece of iron according to our own plea-

(145)

24 Quarterly German Magazine.

sure. Such magnets are called electro-magnets. They can,
if the current be strong enough, attain to very great power,
so that we can hang some hundred weight of iron on them,
which they can carry, but it falls away from it, as soon as
the current is interrupted. By this means, it is possible to
produce electrical motions in a distant place. For instance,
if we place a chain in Berhn and conduct the wires as far
as Cologne to an electro-magnet, the magnet in Cologne ^^'iU
attain its magnetism and lose it again, as soon as we open
and shut the chain in Berlin. A piece of iron brought in
Cologne near the electro-magnet, a so-caUed anchor.^ w^hich
is kept in equilibrium by a spring, wiU be attracted to it as
soon as the current is closed in Berlin, and is again detached
if the current be opened. We can use these motions to give
signs.

We can also set machines in motion with the help of
electro-magnetism. If, for example, we bind a hook to the
anchor (as it is fixed to the pendulum of clocks which are
placed against the wall), which interlocking in the spokes of
a wheel, set it turning, we can set the hand of a clock in re-
gular rotation, if the closing and opening takes place regularly.
This last can be efiected by the pendulum of a clock, but
then the electro-magnetically moved hand must keep con-
tinually the same pace as the closing and opening of the
clock. As, how^ever, we can insert many such electro-magnets
with clock work in the same conduction, we can also, by
means of one clock, keep many others, in the most different
places, in the strictest unity with one another.

It has also been tried to employ electro-magnetism to
raise burdens, but the machines which are necessary for the
purpose, are much too expensive to be brought into practice.

(146)

On Electric Phenomena. 25

In cases where less power is necessary, the electro-magnetic
machine can be used. The most important, because it is
much required in science, is the little machine, which the op-
tician Wagner in Frankfurt on the Maine has invented, and to
whom the German Confederation promised one hundred thousand
guldens, if he could construct an electro-magnetic engine. He
was not able to construct the engine, but the little apparatus
which he invented on this occasion, has made his name im-
mortal. It is called after him Wagner's Hammer.

A Httle electro-magnet stands perpendicularly, and above
it swings an iron anchor which is fastened to a lever. The
lever is pressed by means of a spring against a platina spike
and the current of the chain is so arranged, that it goes from
the lever to the platina spike, from thence to the coils of the
electro-magnet, and then back again to the chain. Through
that the magnetism ceases, the anchor is no longer attracted,
and the spring again presses the lever against the spike. Now,
if the current be again closed, the anchor will be again at-
tracted and the current interrupted, and thus the apparatus
continues in play, as long as the chain has a current to de-
velop.

Dr. Siemens has made a very ingenious application of
this apparatus, in telegraphy. It is, however, especially ap-

I plied medically, to stimulate the muscles and nerves. The sti-
mulus takes place at the moment, in which the current is
closed and interrupted. It is, like the closing and opening,
I only of short duration. If the stimulus should last longer,
then the closing and opening of the current, must be succes-
sively repeated, which can best be effected by Wagner''s Ham-
mer. It is, however, much more expedient to use for the
purpose of stimulation, such currents which only last for a

1872. II. 1. (147) c

26 Quarterly German Magazine.

short time, so that the opening follows almost immediately
on the closing. If we have two coils of wire, of which the
one is united to the chain, and therefore a permanent current
flows through it, while the other is united to the multipUca-
tor, no part of the current from the chain can go through
the second roll, and the needle of the multiplicator therefore
does not deviate. As soon as the current in the first coil is
interrupted and then again closed, we see a sudden motion
in the needle of the multiplicator. As both coils stand near
each other, the first coil influences the second, and indeed in
such a manner, that every time the current rises in the first
coil, another is excited in the second, which takes an oppo-
site direction; but when the current in the first coil disap-
pears, then a current rises in the second coil, which flows in
the same direction. The currents which show themselves in
the second coil, are called induced magnetism or magnetic in-
duction. They only last as long as the act of closing and
opening in the first coil. In consequence of this short dura-
tion they are especially suited to stimulate the muscles and
nerves. Indeed, if we let an, induced current go through a
muscle, we can see, each time, that the current in the first
coil is closed or interrupted, that a sudden contraction, a so-
called convulsive motion of the muscles takes place. But if
we insert one of Wagner's hammers in the circuit of the
chain near the first coil, so that the current is continuall)'
closed and interrupted, the single induced currents follow each
other very quickly, and the muscle falls into a continual con-
vulsive state,

Induced currents can also be produced by the magnet.
If we bring a magnet quickly near a coil, a momentary cur-
rent is produced in one direction; but when we remove the

(148)

I

On Electric Phenomena. 27

magnet, then a current is formed in an opposite direction.
Naturally, the same occurs, when the magnet is at rest, and
the coil in motion. This is most efficiently acquired, when
two coils are set in quick rotation before the end of a magnet
in the form of a horse-shoe. As the coils alternately approach
and retreat from the end of the magnet, a quantity of com-
pressed induced currents are produced, which are conveyed
outwardly by trailing springs.

The efPect is essentially increased, if we put in the coils
a piece of soft iron curved like a horse-shoe, which must be
!set in motion with the coils. Through the approach of the
soft iron towards the magnet and its retreat from it, it be-
comes alternately magnetic and non-magnetic, and through
fthis appearing and disappearing of magnetism, induced
currents are also produced in the coils. In this manner
the magneto - electric rotation macliine is formed, which
is used for medical purposes, and which we often see
at fairs, where everybody for a small sum can have the
pleasure of trying the wonderful effects of electricity on his
: own person.

The effect of induction through the rise and disappearance
of magnetism, can be united with the first kind of induction
through the closing and opening of a permanent current. If
we, for example, put a piece of soft iron in the first coil, it
will become magnetic, if the current be closed, and the ma-
gnetism ceases as soon as the current is opened. In this
manner, the induced current in the second coil is greatly
strengthened. Apparatuses of this kind are principally used
medicinally. Through the faciHty, with which it stimulates
the nerves and muscles, medical science has not only obtained
an important remedy for curing the diseases of these organs,

(149)

28 Quarterly German Magazine,

but also the scientific investigation of the actuahty of their
structure has made great progress.

The inducted currents are very similar to those obtained
by electric friction. Like those, they also give a shock with
light and noise, when the circle is interrupted in any part.
Lately, apparatuses of this kind have been constructed, which
eject sparks twelve inches long, and sometimes longer. The
inducted sparks are excellently adapted to set mines on fire.

The phenomena which I have here concisely described,
do not in the least exhaust the large sphere of electricity, but
are sufficient to show how the human spirit of enquiry, on the
path of calm examination, is capable of accomplishing some-
thing very great. The researches of which I have endeavoured
to give you a concise view, began at the end of the last
century, but the greater part of them have been made during
the last thirty years. And besides that devastating mighty
power which demonstrates itself in a thunder storm, has been
forced into the service of man, and he has made it as the
bearer of thoughts, the medium of intercourse between the
most distant parts of the earth, so that that which formerly
only served to lay houses in ashes, now, instead of fire,
melts metals in prescribed forms; and that which only dis-
troyed human beings, is now used as a remedy to eradicate
diseases. Who can say, what further progress the future can
bring us? We can be justly proud of our century, which is
decried by many as so material, and still in which the human
mind has celebrated not the least of its triumphs.

PrinUd by Unger Brothers (Th. Orimm), Berlin, Scbonebergeratr. 17a.

U_L_W

.<?^ %

■imjpf'

'^mf^

■r-^/

%jy^

jp.^£^^^^

^mu