Improvements in or connected with Electrical Condensers.
Year: 1896

page_text: Date of Application, 15th Jan, 1896
Complete Specification Left, 14th Oct., 1896-Accepted, 15th Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in or connected with Electrical Condensers.
"I CHARLES POLLAK of 253 Mainzer Landstrasse Frankfort-on-Maine in the
German Empire Managing Director of the Accumulatoren Werke System Pollak
a Joint Stock Company of Frankfort-on-Maine aforesaid do hereby declare the
nature of this invention to be as follows:-
This invention relates to electrical condensers and has for its object to provide
a condenser of far greater capacity than has such apparatus as hitherto made.
The invention is based upon the observation, which I have made, that if, in an
electrolytic cell, the electrodes be such that, when the current passes through
them, the plate, acting as a positive electrode for the time being, becomes covered.
with a film or coating, the effect of which is to insulate the metal of the plate from
the electrolyte or, at all events, to offer a considerable resistance to the passing
current, then a current of corresponding tension (say 100 volts) is precluded from
passing through the cell altogether. And if the circuit be then broken, and the
cell connected with a galvanometer, the impulse of the latter will correspond to the
tension of the charging current. Hence it follows that the useful work or energy,
of the current becomes stored up in the electrode. By the utilization of this fact
I have produced an improved electrical condenser of great capacity.
The invention is best carried out in the following manner
In a vessel or jar, containing an alkaline electrolyte, two aluminium plates, or
electrodes, are arranged. The electrolytic cell thus formed is then introduced
into the circuit for which the condenser is intended. So long as the direction
in which the current is sent through remains the same, an insulating coating will
form upon the positive electrode, which, in a short time, will oppose a high degree
of resistance to the current, and will, in consequence, result in a polarization (or a
charge, as the case may be) corresponding to the tension of the charging current.
By interrupting the flow of the current at this juncture, phenomena such as take
place as a consequence of the charging of a Leyden jar (but more considerable
quantitively) will be observable. The charging and discharging may be repeated
as many times as desired. In the case of alternate currents, the same effects will
be produced upon both plates, because the insulating or coating formed by the
passing current no longer offers any resistance to the current, directly the current
begins to exercise a reducing action thereon, or in other words, as soon as the
coated plate becomes a negative electrode. But while it so ceases from setting up
a resistance in the way of the current, yet the said coating does not quite.
disappear. It is for this reason that the employment of two aluminium electrodes
is necessary in the case of alternate currents, whereas, where uniform currents
have to be dealt with, the negative plate may, if desired consist of any other
suitable insoluble conductor.
Inasmuch as the capacity of an electrical condenser such as this depends upon
the size or area of its surface the following method may be adopted in constructing
a condenser which, while possessing a sufficient area to ensure the considerable
capacity it is required to have, is yet compact in its construction and of small
weight.

page_text: The aluminium employed should be of a porous nature, or, at any rate, it should
present a porous surface. The methods of manufacture of porous plates of this
description are well known and easy enough to perform.
I have noticed that under the conditions named it takes a long time to complete
the first charge and that in some cases it becomes practically impossible to effect a
charge at all, and this because the coating required for charging does not always
form in a homogeneous condition under the influence of the working conductor
or wire.
To remedy this incovenience it is advisable to prepare and "form" the plates
beforehand. For this purpose the plates are first properly cleansed with a suitable
corrosive, washed, and then placed in the alkaline solution wherein it is left for
about twelve hours. A weak uniform current is then for a considerable time sent
through them, with more or less protracted intervals of rest, the plate to be
coated serving as a positive electrode. This is continued until the tension of
current, in the cell can rise no further, having attained the degree of tension of the
charging current. The plates are then left within the circuit for several hours
longer when the "formation process" is completed.
Instead of aluminium, any other metal may be employed, provided it has the
property of assuming a homogeneous insulating coating under the influence of the
passing current when used as a positive electrode, and of offering no resistance to
the current, when it passes in the opposite direction, without however even then
completely disappearing or becoming reduced to the condition of spongy metal.
Similarly the alkaline solution may be replaced by any other suitable electrolyte
(say, a gas, if desired, or any convenient solid or semi-solid body) which under
the circumstances named will form a coating such as is above described upon the
positive electrode.
The electrical condenser herein described may be employed similarly to a
statical condenser, over which however it has the advantage of increased capacity,
whereby it is fitted for more general use.
Dated this 15th day of January 1806
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.
Improvements in or connected with Electrical Condensers.
I, CHARLES POLLAK of 253 Mainzer Landstrasse, Frankfort-on-Maine in the
German Empire, Managing Director of the Accumulatoren Werke System Pollak,
a Joint Stock Company of Frankfort-on-Maine aforesaid, do hereby declare the
nature of this invention and in what manner the same is to be performed to
be particularly described and ascertained in and by the following statement :-
This invention relates to electrical condensers and has for its object to provide a
condenser of far greater capacity than has such apparatus as hitherto made. The
invention is based upon the observation which I have made, that if, in an electrolytic
cell, the electrodes be such that, when the current passes through them, the plate
acting as a positive electrode for the time being, becomes covered with a film or
coating, the effect of which is to insulate the metal of the plate from the
electrolyte, or at all events, to offer a considerable resistance to the passing current,
then a current of corresponding tension (say 100 volts) is precluded from passing
through the cell altogether. And if the circuit be then broken, and the cell
connected with a galvanometer, the impulse of the latter will correspond to the

page_text: tension of the charging current. Hence it follows that the useful work, or energy
of the current becomes stored up in the electrode. By the utilization of this fact
I have produced an improved electrical condenser of great capacity.
The invention is best carried out in the following manner:
In a vessel or jar, containing an alkaline electrolyte two aluminium plates, or
electrodes are arranged. The electrolytic cell thus formed is then introduced
into the circuit for which the condenser is intended.
So long as the direction in which the current is sent through remains the same,
an insulating coating will form upon the positive electrode, which, in a short time,
will oppose a high degree of resistance to the current, and will in consequence,
result in a polarization (or a charge, as the case may be) corresponding to the
tension of the charging current. By interrupting the flow of the current at this
juncture, phenomena such as take place as a consequence of the charging of a
The
Leyden jar (but more considerable quantitively) will be observeable.
In the case
charging and discharging may be repeated as many times as desired.
of alternate currents, the same effects will be produced upon both plates, because
the insulating or coating formed by the passing current no longer offers any
resistance to the current, directly the current begins to exercise a reducing action
thereon, or in other words, as soon as the coated plate becomes a negative
electrode. But while it so ceases from setting up a resistance in the way of the
current, yet the said coating does not quite disappear. It is for this reason that
the employment of two aluminium electrodes is necessary in the case of alternate
currents, whereas, where uniform currents have to be dealt with, the negative
plate may, if desired, consist of any other suitable insoluble conductor.
Inasmuch as the capacity of an electrical condenser such as this depends upon
the size or area of its surface the following method may be adopted in constructing
a condenser which, while possessing a sufficient area to ensure the considerable
capacity it is required to have, is yet compact in its construction and of small
weight. The aluminium employed should be of a porous nature or, at any rate, it
should present a porous surface. The methods of manufacture of porous plates
of this description are well known and easy enough to perform.
I have noticed that under the conditions named, it takes a long time to complete
the first charge and that in some cases it becomes practically impossible to effect a
change at all, and this because the coating required for charging, does not always
form in a homogeneous condition under the influence of the working conductor or
wire.
To remedy this inconvenience, it is advisable to prepare and "form" the plates
beforehand. For this purpose the plates are first properly cleansed with a suitable
corrosive washed, and then placed in the alkaline solution, wherein it is left for
about twelve hours. A weak uniform current is then for a considerable time sent
through them, with more or less protracted intervals of rest, the plate to be coated
serving as a positive electrode. This is continued until the tension of current, in
the cell, can rise no further, having attained the degree of tension of the charging
current. The plates are then left within the circuit for several hours longer, when
the "formation process" is completed.
Instead of aluminium, any other metal may be employed provided it has the
property of assuming a homogeneous insulating coating under the influence of the
passing current, when used as a positive electrode and of offering no resistance to
the current when it passes in the opposite direction, without however, even then,
completely disappearing, or becoming reduced to the condition of spongy metal.
Similarly, the alkaline solution may be replaced by any other suitable electrolyte
(say, a gas, if desired, or any convenient solid or semi-solid body) which under
the circumstances named will form a coating such as is above described upon the
positive electrode.
The electrical condenser herein described may be employed similarly to a
statical condenser, over which, however it has the advantage of increased
capacity, whereby it is fitted for more general use.
:
"

page_text: Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed 1 declare that what I
claim is :-
1. An electrical condenser consisting of an electrolytic cell wherein the electrical
current, as it passes through it, under the influence of an alkaline or neutral
solution or electrolyte, covers that which for the time being, is the positive
electrode, with a coating, capable of offering a high degree of resistance to the
current; the effect of it being a polarization, or charge, (as the case may be), the
power of which corresponds to the tension of the charging current; such coating
offering no resistance to an opposite current, although it does not altogether
disappear under its influence.
2. For an electrical condenser, such as is referred to in the preceding claim, a
plate for acting as a positive electrode for the time being the said plate having
been provided by a "forming " process, with a coating as hereinbefore
described.
Dated this 14th day of October 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.