Improvements in Carbons or Electrodes used in Arc Lamps for Electric Lighting.
Year: 1894

page_text: a
Date of Application, 16th Oct., 1894
.
2
1005
Otat Cant
1905
Date of Application, 10th Oct., 1894
Complete Specification Left, 10th Aug., 1996 Accepted, 21st Sept.,
1905
PROVISIONAL SPECIFICATION.
Improvements in Carbons or Electrodes used in Arc Lamps for
Electric Lighting.
I ALFRED FRANCIS BILDERBECK GOMESS of 24 Alfred Place West, South
Kensington, in the -County of London, Chemist, do hereby declare the nature of
this invention to be as follows:-
The object of my invention is to remove several of the chief drawbacks
incidental to the present method of electric are lighting: namely those connected
with the carbons or electro les mile use of in that system of illumination.
The carbon electrodes as at present employed require constant attention and are
consumed so rapidly that they have to be renewed at frequent intervals; and
although various attempts have been made from time to time to remove these
drawbacks, all these endeavours have been attended with but a small measure OL
success.
'
It has been proposed, amongst other plans, to cover or coat the carbons by
electro-deposition or otherwise, with coatings of metal or other substances, but
these coatings whilst having little influence upon the life of the carbons, have
frequently diminished the amount of light emanating from the electric are to a
serious extent, or, on account of the substances used for the coatings, have
impaired the quality or altered the colour of the light in a most undesirable
manner.
"
i.
The object of my invention is to increase the life of the carbon or electrode to
a very considerable and important extent, without at the same time impairing the
light emitted by the arc; in fact, with candles manufactured according to my
invention the amount of light is considerably increased and its quality and colour
greatly improved.
According to my invention I coat the carbons or electrodes by electro-deposition
with the various coatings hereafter described arranged in any suitable order, the
arrangement hereinafter described being one that I have found to produce good
results in practice.
I render the surface of the carbons or electrodes a conductor of electricity
by any suitable means, such for instance as depositing copper thereon, in order to
enable me to electro-deposit the aluminium or magnesium or alloys of these metals
as hereafter described.
Upon the negative carbon or electrode I electro-deposit a coating of copper (by
any of the methods in common use) then a coating of magnesium, and over this
latter a coating of aluminium or aluminium alloy, such for instance as an alloy of
aluminium with 10% of tin.
Upon the positive carbon or electrode I electro-deposit a coating of copper
and then a coating of aluminium or aluminium alloy: but preferably no
magnesium.
I prefer to make the coatings on the positive considerably thicker than those on
the negative carbon or electrode.
I also prefer that the aluminium used for the coatings shall be impure.

page_text: Although I have described three coatings upon the negative and two upon the
positive carbon or electrode, 1 do not wish to limit myself to any particular number
or arrangement of coatings.
J
The following are the compositions of three baths which I propose to employ
for depositing the magnesium or magnesium alloy upon the carbons or electrodes,
previously coppered or otherwise suitably prepared.
(1) A double tartrate of magnesium and ammonium in conjunction with chloride
of an alkali, such as ammonium chloride.
(2) A double acetate of magnesium and ammonium in conjunction with chloride
of an alkali, such as ammonium chloride.
(3) A double citrate of magnesium and ammonium, in conjunction with chloride
of an alkali, such as ammonium chloride.
The bath I employ for coating with aluminium is composed of tartrate of
aluminium in conjunction with chloride of an alkali, either with or without the
addition of iodide or bromide of an alkali.
The following is the composition of a bath which I propose to employ :-
of an alkali, such as ammonium chloride.
The bath I employ for coating with aluminium is composed of tartrate of
aluminium in conjunction with chloride of an alkali, either with or without the
addition of iodide or bromide of an alkali.
:-
The following is the composition of a bath which I propose to employ :-
Tartrate of aluminium
Ammonium chloride
Water
-
10 parts.
-
1 part.
160 parts.
Instead of using tartrate of aluminium I may use its isomers, or I may use the
salt derived from other suitable acid containing two carboxyl groups in the
molecule. For example the salts derived from oxalic acid, succinic acid, malic
acid or phthalic acid.
In order to electro-deposit the aluminium upon the carbon or electrode, previously.
coated with copper or otherwise suitably prepared, I connect the said carbon or
electrode with the negative pole of a dynamo or battery, and I either use aluminium
anodes or I use an anode of carbon, platinum or other suitable material (e.g. one
that will not dissolve in the aforesaid bath) surrounded by hydrated oxide of
aluminium. This may be done by placing the anode in a porous cell in the
electrolyte. This cell is charged with the hydrated oxide of aluminium so as to
keep the latter in close contact with the positive pole.
When I coat with an aluminium anode I work the bath in a neutral or slightly
alkaline state, but when the other anodes above described are used the bath can be
worked in an acid, neutral or alkaline state.
I prefer that the bath should contain a double tartrate of aluminium and alkali,
and this will always occur when the bath is in a neutral or nearly neutral
condition.
1 ..
When it is desired to coat the carbon or electrode with aluminium alloys I add
to the bath above described or place within the porous cell, a tartrate or chloride
of the metal, which I wish to alloy with the aluminium. When I use chloride of
the metal I may leave out the chloride of an alkali. For instance in the case of
an alloy with tin I add to my bath or place within the porous cell about 10%
of chloride of tin.
Dated this Sixteenth day of October 1894'

page_text: Improvements in Carbons or Electrodes used in Arc Lamps for
Electric Lighting.
I ALFRED FRANCIS BILDERBECK GOMESS of 24 Alfred Place West, South
Kensington in the County of London, Chemist 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 :-
The object of this invention is to remove several of the chief drawbacks
incidental to the present method of electric are lighting, namely those connected
with the carbons or electrodes made use of in that system of illumination.
The carbon electrodes as at present employed require constant attention and
are consumed so rapidly that they have to be renewed at frequent intervals; and
although various attempts have been made from time to time to remove these
drawbacks, all these endeavours have been attended with but a small measure of
success.
It has heen proposed, amongst other plans, to cover or coat the carbons by
electro-deposition or otherwise with coatings of metal or other substances, but these
coatings whilst having but little influence upon the life of the carbons, have,
frequently diminished the amount of light emanating from the electric arc to a
serious extent; or, on account of the substances used for the coatings, have,
impaired the quality or altered the colour of the light in a most undesirable!
manner.
The object of my invention is to increase the life of the carbon or electrode to
a very considerable and important extent, without at the same time impairing the
light emitted by the are: in fact with candles manufactured according to my.
invention the amount of light is considerably increased, and its quality and colour
greatly improved.
According to my invention I coat the carbons or electrodes by electro-deposition.
with the various coatings hereafter described, arranged in any suitable order, the
arrangement hereinafter mentioned being one that I have found to produce good
results in practice.
.1
I render the surface of the carbons or electrodes a better conductor of electricity
by any suita ole means, such for instance as depositing copper thereon, in order to
enable me to electro-deposit, aluminium or magnesium or alloys of these metals as
hereafter described.
Upon the negative carbon or electrode I electro-deposit a coating of copper by
any of the methods in common use; then a coating of magnesium, and over this
latter a coating of aluminium or aluminium alloy, such for instance as an alloy of
aluminium with ten per cent. of tin.
:
"
Upon the positive carbon or electrode I electro-deposit a coating of copper..
and then a coating of aluminium or aluminium alloy but preferably no
magnesium.
.
I prefer to make the coatings on the positive considerably thicker than those on
the negative carbon or electrode.
I also prefer that the aluminium used for the coatings shall be impure.
Although I have described three coatings upon the negative, and two upon the
positive carbon or electrode, I do not wish to limit myself to any particular number
or arrangement of coatings.
The following are the compositions of three baths which I propose to employ for
"

page_text: Water
160 parts.
Instead of using tartrate of aluminium I may use its isomers, or I may use the
salt derived from other suitable acid containing two carboxyl groups in the molecule,
for example the salts derived from oxalic acid, malic acid, succinic acid, or phthalic
acid.
In order to electro-deposit the aluminium upon the carbon or electrode,
previously coated with copper or otherwise suitably prepared and in the case of
the negative electrode further coated with magnesium or magnesium alloys, I
connect the said carbon or electrode with the negative pole of a dynamo or
battery, and I either use aluminium anodes or I use an anode of carbon, platinum
or other suitable material (e.g. one that will not dissolve in the aforesaid bath)
surrounded by hydrated oxide of aluminium. This may be done by placing the
anode in a porous cell in the electrolyte. This cell is charged with the hydrated
oxide of aluminium, so as to keep the latter in close contact with the positive pole.
When I coat with an aluminium anode I work the bath in a neutral or slightly
alkaline state, but when the other anodes above described are used the bath can
be worked in an acid neutral or alkaline state.
I prefer that the bath should contain a double tartrate of aluminium. and alkali,
and this will always occur when the bath is in a neutral or nearly. neutral
condition.
When it is desired to coat the carbon or electrode with aluminium alloys I add
to the bath above described or place within the porous cell a tartrate or chloride
of the metal which I wish to alloy with the aluminium. When I use chloride of
the metal I may leave out the chloride of an alkali. For instance in the case of
an alloy with tin, I add to my bath or place within the porous cell about ten per cent.
of chloride of tin.
In order to plate with magnesium alloys, when desired, I add to the baths above
described for plating with magnesium, a tartrate or chloride of the metal which I
wish to alloy with the magnesium, for example in the case of an alloy with tin, I
add about 5 to ten per cent. of chloride of tin.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. Carbons or electrodes used in electric arc lighting coated by electro-
deposition with aluminium and magnesium or alloys of these metals for the
purposes described.

page_text: 2. Carbons or electrodes used in electric arc lighting, coated by electro-
deposition with aluminium or aluminium alloys for the purposes described.
3. Carbons or electrodes used in electric arc lighting coated by electro-
deposition with magnesium or magnesium alloys for the purposes described.
4. In electric arc lighting the employment of a negative electrode coated by
electro-deposition with magnesium or magnesium alloys, and aluminium or
aluminium alloys, in combination with a positive electrode in which the magnesium
or magnesium alloy is omitted, for the purposes described.
5. The improved carbons or electrodes used in electric arc lighting, substan-
tially as described.
Dated this Sixtaanth day of Awoust 1005
BROWNE & Co.,
9 Warwick Court, Gray's Inn, London, W.C.,
Agents for the Applicant.