MENTS IN ELECTRODES USED AS EARTH PLATES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by the said Desmond Gerald Fitz-Gerald
at the Office of the Commissioners of Patents on the 7th June 1883.
DESMOND GERALD FITZ-GERALD of Brixton in the County of Surrey
MENTS IN ELECTRODES USED AS EARTH PLATES "
"
IMPROVE-
My Invention relates to circuits for the production of electric illumination or the
transmission of energy, or generally to circuits in which currents of electricity of
several or many ampères are transinitted, and in which the earth is used as portion
of the circuit. In ordinary telegraphic circuits, where the current is but a small
fraction of an ampère, and is moreover frequently reversed, it has been found that
gas or water pipes, or small plates of metal in contact with moist soil which is
itself in contact with the great mass of terrestrial water, may very conveniently be
used for the earth connections. But when continuous currents of great magnitude
are to be transmitted through earth, the amount of electro-chemical action at the
anode is sufficient to produce in course of time a detrimental amount of oxidation
in iron or lead pipes and rapidly to destroy a small plate of metal; whilst the
large quantities of hydrogen gas evolved at the cathode lead to variations in the
resistance of the circuit, and to consequent irregularity in the current, accompanied
with a considerable loss of energy. To obviate these objections and to secure
regularity and economy in the working of circuits of which the earth forms part
and in which currents of comparatively great magnitude are transmitted, I construct
the anode earth-plate of a readily-oxidisable metal or of a conductor such as carbon
(or any suitable metal) surrounded with a considerable mass of readily-oxidisable
material such as lead or iron in a porous or finely-divided condition; and I
construct the cathode earth-plate of a conductor, such as carbon or lead, surrounded
with a considerable mass of oxidising material, such as plumbic peroxide or of
other material capable of absorbing or effecting a chemical combination with
hydrogen. The anode and cathode thus constructed constitute un-polarizable
earth plates

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Desmond Gerald Fitz-Gerald in the Great Seal Patent Office on the
7th December 1883.
DESMOND GERALD FITZ GERALD, of Brixton in the County of Surrey IMPROVE-
MENTS IN ELECTRODES USED AS EARTH PLATES
My Invention relates to circuits for the production of electric illumination or
the transmission of energy, or generally to circuits in which currents of electricity
of several or many ampères are transmitted and in which the earth is used as
portion of the circuit.
In ordinary telegraphic circuits where the current is but a small fraction of an
ampère and is moreover frequently reversed, it has been found that gas or water
pipes or small plates of metal in contact with moist soil, which is itself in contact
with the great mass of terrestrial water may very conveniently be used for the
earth connections. When, however, continuous currents of great magnitude are to
be transmitted through earth, the amount of electro-chemical action at the anode
is sufficient to produce in course of time a detrimental amount of oxidation in iron
or lead pipes and rapidly to destroy a small plate of metal; whilst the large
quantities of hydrogen gas evolved at the cathode introduce a high and variable
resistance in the circuit, and consequently produce irregularity in the current,
accompanied with a considerable loss of energy.
To obviate these objections and to secure regularity and economy in the working
of circuits of which the earth forms part, and in which currents of comparatively
great magnitude are transmitted, I construct the anode earth-plate of a readily
oxidisable metal or of a conductor such as carbon (or any suitable metal) surrounded
with a considerable mass of readily oxidisable material (such as lead or iron in a
porous or finely divided condition) or of a conductor surrounded by an oxide or
salt capable of producing a metallic peroxide in presence of nascent oxygen; and I
construct the cathode earth-plate of a conductor (such as carbon or lead)
surrounded with a considerable mass of an oxidising material such as lead
peroxide capable of absorbing or effecting a chemical combination with nascent
hydrogen. The anode and cathode thus constructed constitute unpolarizable
earth plates.
The following are examples of the modes in which my Invention may be carried
into effect
Amalgamated zinc immersed in dilute Sulphuric Acid contained in a porous
vessel in contact with earth, may be employed as an earth-anode in conjunction
with an earth-cathode constituted by a conductor (preferably lead or carbon)
surrounded by an oxidant or "depolarising substance" such as peroxide of lead or
of manganese. When carbon is thus employed at the cathode it is preferable to
surround a central plate or large fragment of the material (gas carbon, coke, or
graphite) with a mass of small fragments of carbon, the interstices between which
are filled with a solid depolarizing substance, preferably peroxide of lead or of
manganese. It is generally necessary, or preferable, to employ a porous vessel, as
in the case of the anode, to contain the cathode and "depolarizing material." Great
care must be exercised in establishing contact between the central plate, or large
fragment of carbon, and its connecting wire in order to prevent the local action
which occurs when such wire is in contact with an electrolytic fluid as well as
with the carbon. In order to obviate such local action, I prefer to coat with copper
by electro-deposition that portion of the central plate or fragment of carbon with
which contact is to be made, then to solder the conducting wire to the coppered

page_text: portions of the carbon, and finally to saturate with an impervious material (such as
paraffin-wax) that portion of the carbon which is in proximity to the soldered
junction. The conducting wire also must be insulated so that no portion of it
can come into contact with electrolytic fluid or moisture. When amalgamated
zinc is thus employed as the earth-anode in conjunction with an earth-cathode of
metal or carbon surrounded with an oxidant or a depolarising substance, (which in
the case of a metal should not be of a nature to exert a chemical action thereupon)
the passage of the current through the earth portions of the circuit, is not only
not impeded, but is facilitated by an electromotive force which is generated at the
earth-plates and which is in the same direction as the electro-motive-force of the
dynamo-machine or other source of electrical supply in the circuit.
I prefer, however, from considerations of economy, to substitute for the amalga-
mated zinc as an earth-anode a plate of lead or of carbon surrounded by a mass of
lead in a state of fine sub-division, or of lead in a porous condition such lead being
preferably immersed in dilute sulphuric acid contained in a porous vessel in contact
with earth, so that the metal is converted into sulphate by the passage of the.
current. From the sulphate thus formed the metal may readily be reduced and
re-converted into metallic (porous) lead by subsequent electrolytic treatment as for
example by the process described in the Specification of a former Patent granted
to myself and Thomas John Jones (No. 1121 of 1883).
Any of the various forms of element constituting efficient "cathodes in
charging" in the case of lead secondary batteries may, when the active material
has been reduced by the passage of a charging current, be advantageously employed
as earth-anodes. And, moreover, any of the various forms of element constituting
efficient "anodes in charging" in the case of lead secondary batteries may, when
the active material has been peroxidised by the passage of a current, be advan-
tageously employed as earth-cathodes. For example I may employ an earth-anode
constructed in the same manner as any of the forms of the "cathode in charging"
described in the Specification of former Letters Patent granted to myself and
Thomas John Jones (No. 4178 of 1882), and I may employ an earth-cathode
constructed in the same manner as any of the forms of the "anode in charging"
described in the Specification of former Letters Patent granted to me (No. 1122
of 1883).
When it is desired to secure the advantage of an electro-motive force acting in
the same direction as that of the source of electrical supply, the earth-anode con-
structed with reduced (porous) lead must be replaced (by switching in a fresh
anode-plate) when the metal has become converted into lead sulphate (or oxide)
and before any portion of the latter has become converted into peroxide. The
earth cathode must similarly be replaced when the peroxide of lead has been reduced
to sulphate (or oxide) of the metal, and before any portion of the latter has become
reduced to the metallic state. But a more economical method of working may be
adopted when it is not desired to facilitate the passage of the current by means of
an electro-motive force generated by the earth-plates themselves. In this case
lead sulphate (or oxide) may be converted into lead peroxide at the earth-anode;
whilst lead peroxide is converted (by absorption of hydrogen) into lead sulphate
(or oxide) at the earth-cathode. The total electro-chemical work done in this
latter method of working (by the earth-couple and by the source of electrical
supply) being nil (the work done at the anode being undone at the cathode, or
vice versa) there will in this case be no electro-motive force either facilitating or
opposing the passage of the current, but the gases (oxygen and hydrogen) set free
by electrolysis, at the earth-anode and earth-cathode respectively, being freely
absorbed, there will be no detrimental or varying resistance in the earth portion
of the circuit, and thus an important economical advantage is secured. In this
method of working, when the lead sulphate (or oxide) at the earth-anode has been
converted into lead peroxide, this anode has been converted into an earth-plate
suitable for the earth cathode, and reciprocally when the lead peroxide at the earth.
cathode has become converted into lead sulphate (or oxide) this cathode has become

page_text: converted into an earth-plate suitable for the earth-anode. By merely alternating
the position of the plates, therefore, the circuit may be worked without waste of
energy, through the generation of a high resistance consequent upon the liberation
of large quantities of gas in contact with the earth plates and without any
expenditure of material, or any necessity for "reforming" the earth-electrodes.
The electrolytic production of lead peroxide or of metallic lead from the sulphate
of the metal being greatly facilitated by the presence in the electrolyte of a
substance which has a solvent action upon the sulphate, it is usually desirable,
when lead sulphate is to be converted, to employ as the electrolyte a solution of
the sulphate, tartrate or acetate of ammonia, which solution may be acidulated
with sulphuric acid. More especially when lead sulphate is to be converted into
peroxide of the metal and free sulphuric acid (as in the method of working last-
described) it is necessary to employ as electrolyte a solution, such as those of the
salts mentioned, having the solvent action in question. In this case it is unnecessary
to acidulate the solution, which should be contained in a porous vessel in contact
with earth. And when lead peroxide is to be reduced by nascent hydrogen,
liberated at the earth-cathode, it is advantageous that an electrolyte of dilute
sulphuric acid (contained in a porous vessel in contact with earth, and sufficient in
quantity to convert the whole of the lead peroxide into sulphate of the metal)
should be employed.
Having described the nature of the said Invention and the manner of performing
the same I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is :
1 The combination in an electrical circuit wherein continuous currents are
transmitted, of an anode earth-plate constructed of a readily oxidizable metal, or
of a conductor surrounded with a readily oxidizable material, or of a conductor
surrounded by an oxide or salt capable of producing a metallic peroxide in presence
of nascent oxygen, and a cathode earth-plate constructed of a conductor surrounded
with an oxidant or depolarising material capable of absorbing or readily combining
with nascent hydrogen, substantially as specified.
2nd The combination, in electrical circuits wherein continuous currents are
transmitted, of an earth-cathode capable of readily absorbing nascent hydrogen
and any suitable anode earth-plate such as have been heretofore used, substantially
as specified.
In witness whereof I the said Desmond Gerald FitzGerald, have hereunto set
my hand and seal this Seventh day of December A.D. 1883.
Witness
WM CLARK
53 Chancery Lane
Patent Agent.
DESMOND. G. FITZ-GERALD. (L.S.)