An Improved Cell for Controlling the Direction of Flow of Electric Currents, or Retarding such Flow, and for like purposes.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
An Improved Cell for Controlling the Direction of Flow of Electric
Currents, or Retarding such Flow, and for like purposes.
A communication by Dr. LEO GRATZ, of 8, Arcisstrasse, Munich, in the Empire
of Germany, University Professor.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6 Bank Street, Manchester, both in
the County of Lancaster, 118 New Street, Birmingham, in the County of Warwick,
and 322, High Holborn, in the County of Middlesex, Civil Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention has for its object a cell for controlling the direction of flow of
electric currents or retarding such flow and for like purposes, and is based on the
property possessed by an aluminium anode of strongly diminishing the flow of
current in an electrolyte which separates oxygen at the anode directly or by means
of secondary processes.
This property of aluminium has been attributed to the formation of a very bad
conducting layer on the anode, that is to say of a resistance, but the correct ex-
planation should be sought in the production of a kind of polarization of very
considerable extent, or of a condenser action, and measurements undertaken for
this object have shown that the counter forec resulting thereby amounts to
22-25 volts.
In order to render this property of aluminium of practical value, a cell is
employed having one electrode of aluminium or an aluminium alloy, whilst the
other electrode is formed of any suitable conducting substance (such as, for
instance, carbon, iron, copper or the like). For the electrolyte a liquid is em-
ployed possessing the property of separating oxygen at the anode directly or by
secondary processes, and a solution of soda-alum or potash-alum, dilute sulphuric
acid, and the like is found to be suitable for this object. Liquids which attack
aluminium, such as soda-lye, may, under certain crcumstances, be also employed
as electrolyte.
Such a battery possesses the property of extraordinarily diminishing and even
entirely suppressing the flow of an electric current passing therethrough in the
direction in which the aluminium is the anode, whilst it gives no practical
resistance to the passage of the current in the opposite direction.
Currents of weak tension (under 22-25 volts) flow in the direction of the
aluminium anode, either not at all, or only to a very reduced amount, while
currents of stronger tension are entirely choked or weakened to a very considerable

page_text: extent by a number of such cells inserted in series in the same direction, according
to the number of such cells and the tension. In order to fully choke such a
current of known tension so many batteries must be connected in series that their
combined power together equalizes the given tension.
These cells, which on account of their property of choking the current in one
direction and yet allowing it to pass through in the other may suitably be called
"choking cells," are in practice capable of many applications. Such cells may,
for instance, be largely employed in electric signalling, and more particularly in
telegraphy. If such cells be inserted in the circuit of a simple or branch con-
ductor system, they allow a flow of the current in one direction, whilst in the
opposite direction the current is to a certain extent arrested. For instance,
choking cells" may serve for entirely removing the back current in cable
telegraphy and to render it thereby harmless. They may also in multiplex
telegraphy hinder the passage of the current through such apparatuses as are not
intended to be influenced. If the "choking cells" are not required to stop
the entire current but only to diminish the flow to a given great extent, the
number of such cells inserted in series must be smaller than can absorb the entire
tension of the original current. The following may be given as an example of
this. If only one arc lamp be inserted between two conductors of a difference
of potential of from 100-110 volts, 2-3" choking cells" must be inserted in front
of the lamp, in which cells the aluminium electrode is the anode. By this means
the tension for the lamp is diminished to 50-60 volts without having to insert a
considerable resistance. In such cases the cathode may also be formed of
aluminium.
A further use of these "choking cells" consists in their application as com-
utators in order to convert alternating current into continuous current. If
an alternating current of given tension be passed through such a number of said
"choking cells" inserted in series, that the anode polarization at least, equalizes
the tension, there will pass through these cells only those parts of the alternating
current for which the aluminium is the cathode. There is obtained thus in the
outer circuit a continuous current, as only the negative parts of the current can
pass the choking cells," whilst the positive parts are choked off in the same.
This current has in any case only a half current strength. It must be here noted,
however, that the power of work of the machine is also only the half, as the
positive current parts have a current strength of O. It will be necessary there-
fore in order to obtain the same effect to always employ a machine of double size.
This may be avoided however by inserting two series of "choking cells" in such
a way that the current finds a passage in one direction in the one series, and in
the other direction in the other series, the two currents being conducted through
the same wire by a further insertion of choking cells."
For this object the current is conveyed from the two poles of the alternating
current machine through two batteries of "choking cells," one at each pole
These two batteries are connected in the rear with one another. Further, the
poles of the machine are connected with two other batteries, one to each pole
which are inserted in an opposite direction to the other two batteries and are also
connected in the rear with one another. Thus each pole of the machine is con
nected both with an aluminium electrode, and also with an electrode formed of
carbon, or of other suitable material. The outer line wire through which th
constant current is intended to flow is attached to the connecting wire of the on
pair of batteries and to the connection of the other pair of batteries. What ve
sign the poles of the machine may have, there will always flow a continuou
current through the outer line wire.
As the negative polarization of such a cell is only about a twentieth part of the
positive polarization, the effect of the alternating current is converted up to 95%
into continuous current; so long as the, resistance of the cells is made very smal
by the use of sufficiently large electrodes and by placing the plates a small distance
apart.

page_text: Wherever in the foregoing specification aluminium electrodes have been
referred to, it is understood that in their place electrodes, of any aluminium alloy.
may always be employed.
1: 101 of Andalu 1907
An Improved Cell for Controlling the Direction of Flow of Electric
Currents, or Retarding such Flow, and for like purposes.
A communication by Dr. LEO GRATZ, of 8, Arcisstrasse, Munich, in the Empire
of Germany, University Professor.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster, 118 New Street, Birmingham, in the County of Warwick,
and 322 High Holborn, in the County of Middlesex, Civil Engineer, 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 has for its object a cell for controlling the direction of flow of
electric currents or retarding such flow and for like purposes, and is based on the
property possessed by an aluminium anode of strongly diminishing the flow of
current in an electrolyte which separates oxygen at the anode directly or by means
of secondary processes.
This property of aluminium has been attributed to the formation of a very bad
conducting layer on the anode, that is to say of a resistance, but the correct ex-
planation should be sought in the production of a kind of polarization of very
considerable extent, or of a condenser action, and measurements undertaken for
this object have shown that the counter force resulting thereby amounts to 22-25
volts.
In order to render this property of aluminium of practical value, a' cell is em-
ployed having one electrode of aluminium or an aluminium alloy, whilst the
other electrode is formed of any suitable conducting substance (such as, for
instance, carbon, iron, copper or the like). For the electrolyte a liquid is em-
ployed possessing the property of separating oxygen at the anode directly or by
secondary processes, and a solution of soda-alum or potash-alum, dilute sulphuric
acid, and the like is found to be suitable for this object. Liquids which attack
aluminium, such as soda-lye, may, under certain circumstances, be also employed
as electrolyte.
Such a battery possesses the property of extraordinarily diminishing and even
entirely suppressing the flow of an electric current passing therethrough in the
direction in which the aluminium is the anode, whilst it gives no practical resis-
tance to the passage of the current in the opposite direction.
Currents of weak tension (under 22-25 volts) flow in the direction of the
aluminium anode, either not at all, or only to a very reduced amount, while
currents of stronger tension are entirely choked or weakened to a very considerable
extent by a number of such cells inserted in series in the same direction, according
to the number of such cells and the tension. In order to fully choke such a
current, of known tension so many batteries must be connected in series that their
combined power together equalizes the given tension."

page_text: These cells, which on account of their property of choking the current in one
direction and yet allowing it to pass through in the other may suitably be called
choking cells," are in practice capable of many applications. Such cells may,
for instance, be largely employed in electric signalling, and more particular y in
telegraphy. If such cells be inserted in the circuit of a simple or branch con-
ductor system, they allow a flow of the current in one direction, whilst in the
opposite direction the current is to a certain extent arrested. For instance,
choking cells" may serve for entirely removing the back current in cable
telegraphy and to render it thereby harmless. They may also in multiplex
telegraphy hinder the passage of the current through such apparatuses as are not
intended to be influenced. If the "choking cells" are not required to stop
the entire current but only to diminish the flow to a given great extent, the
number of such cells inserted in series must be smaller than can absorb the entire
tension of the original current. The following may be given as an example of
this. If only one arc lamn be inserted between two conductors of a difference
of potential of from 100-110 volts, 2-3 choking cells" must be inserted in front
of the lamp, in which cells the aluminium electrode is the anode. By this means
the tension for the lamp is diminished to 50-60 volts without having to insert a
considerable resistance. In such cases the cathode may also be formed of
aluminium.
"
A further use of these "choking cells" consists in their application as com-
mutators in order to convert alternating current into continuous current. If
an alternating current of given tension be passed through such a number of said
choking cells" inserted in series, that the anode polarization at least equalizes
the tension, there will pass through these cells only those parts of the alternating
current for which the aluminium is the cathode. There is obtained thus in the
outer circuit a continuous current, as only the negative parts of the current can
pass the choking cells," whilst the positive parts are choked off in the same.
This current has in any case only a half current strength. It must be here noted,
however, that the power of work of the machine is also only the half, as the
positive current parts have a current strength of O. It will be necessary there-
fore in order to obtain the same effect to always employ a machine of double size.
This may be avoided however by inserting two series of "choking cells" in such
a way that the current finds a passage in one direction in the one series, and in
the other direction in the other series, the two currents being conducted through
the same wire by a further insertion of "choking cells."
For this object the current is conveyed from the two poles a and b of the alter-
nating current machine M through two batteries of choking cells" I and II
one at each pole as shown in the accompanying drawing in which the aluminium
electrodes are distinguished by large strokes and the other electrodes by small
ones. These two batteries are connected in the rear with one another. Further,
the poles of the machine are connected with two other batteries I and II, one to
each pole which are inserted in an opposite direction to the other two batteries and
are also connected in the rear with one another. Thus each pole of the machine
is connected both with an aluminium electrode, and also with an electrode formed
of carbon, or of other suitable material. The outer line wire w through which the
constant current is intended to flow is attached at c to the connecting wire of the
one pair of batteries I and II and at d to the connection of the other pair of
hatteries I and II* whatever sign the poles a and b of the machine may have, there
will always flow a continuous current through the outer line wire w.
As the negative polarization of such a cell is only about a twentieth part of the
positive polarization, the effect of the alternating current is converted up to 95%
into continuous current, so long as the resistance of the cells is made very small
by the use of sufficiently large electrodes and by placing the plates a small distance
apart.
Wherever in the foregoing specification aluminium electrodes have been

page_text: referred to, it is understood that in their place electrodes of any aluminium alloy
may always be employed.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is:-
1. Cells having different resistances for the two directions of current flowing
through them (choking cells) consisting of an electrode of aluminium or
aluminium alloy aranged in an electrolyte which separates oxygen at the
aluminium as anode directly or by secondary processes (for example, alum solu-
tions, alkali sulphate, alkali-nitrate, caustic alkali-solutions, acids) in connection
with either:
(a) Another electrode of carbon or any suitable base or noble metal (with the
exception of platinum) or of a metal alloy that is not soluble by chemical action
in the liquid used; or
(6) Any desired electrode in an electrolyte (acids, salts solution) which is divided
from the former by a diaphragm sbstantially as herein before set forth.
2. The application of the herein described choking cells, to simple or branch
circuits for preventing the flow of current in a definite direction through a
conductor, substantially as herein before described.
3. The application and use of the hereindescribed choking cells for lowering the
tension in electrical apparatus by the insertion of the same in front of the device
apparatus or instrument in use in such manner that the aluminium electrode
forms the anode, substantially as described.
4. The application of the herein described choking cells as a commutator
without a rotary part by inserting them between the alternating current machine
and the conducting wire, substantially as described.
5. In the application of the herein described choking cells as commutators for
receiving normal effects, the insertion of several batteries of choking cells in such
a way that each pole of the machine is connected with two batteries having their
electrodes oppositely arranged so that the positive and negative impulses of the
current are caused to pass collectively in a uniform direction through the outer
circuit substantially as described.
1000
WM. P. THOMPSON & Co.,
Agents.