Improvements in Electrolysis.
Year: 1893

page_text: Date of Application, 28th June, 1893-Accepted, 14th Oct., 1893
COMPLETE SPECIFICATION.
Improvements in Electrolysis.
EMILE ANDREOLI Journalist, 18 Somerleyton Road, Brixton S.W. 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 an improved electrolytic apparatus in which a
chloride of sodium or other solution is decomposed into its constituent parts, while
circulating through positive and negative compartments formed by partitions made
of asbestos or kieselguhr or other similar porous porcelain, closely situated between
metallic or carbon cathodes and retort carbon anodes constructed in a very simple,
economical and efficient manner. I will take as an example the decomposition of a
chloride of sodium solution.
Fig. 1. shows two similar slate tanks A and A¹ divided into positive com-
partments P P and negative compartments N N¹ by porous partitions which will
be hereafter described.
B is a main pipe fixed on the front part of the tank on the right hand side which
receives the solution to be electrolysed from a feeding cistern (not shown in the
drawing), through a pipe C. The solution passes into the positive compart-
ments PPP which it fills up by means of the branch pipes D D D D flows
through the outlet branch pipes d d d d and the main pipe E at the rear of the
first. tank A, then traverses the conduit F and enters the main pipe B' of the second
tank and its inlet branch pipes D' D' D' D' D' whence it fills up the positive
compartment P: P1 P. The solution passes more or less rapidly between the
anodes according to the rate at which it is desired to have the liquid aspirated by
a pump, (not shown in the drawing). The electrolyte escapes through d' d' dand
after it has travelled through a series of tanks, is sent back to its reservoir and
returns to the first tank as before stated and so on to all the positive compartments
in which it generates chlorine which is collected as hereinafter described and
illustrated.
The circulation in the negative compartments where caustic soda if formed, takes
place in an identical manner. The solution arrives from a feeding tank (not shown
in the drawing) through the conduit G into the main pipe H and its branch
pipes L L L passes through the negative compartments N N N N, flows out
through the outlet branch pipes and the main pipe M situated at the rear
of the tank A and then traverses the conduit O and enters the main pipe H' and its
inlet pipes L LL' L' passes through the negative compartments and so on, until
it is pumped back to its feeding tank and forced through the main pipe & into the
negative compartments N N of the first tank etc. etc.
Fig. 2 is a side view of the tank, with part of the side removed, showing
the inside of the tank, the carbon anodes, diaphragms and cathode; p p p are the
branch pipes leading the chlorine gas from the positive compartments into the
main pipe P from which it is sent where it can be utilized. B & H are the inlet
pipes; E & M are the outlet pipes.
In order to simplify the construction of the tanks, I can dispense with the main
pipes and with the pipe which connects them; so that on one side, the liquids will
arrive by means of the branch pipes d d d & lll and flow direct into the positive
and negative compartments of the next tank.
The chlorine gas is collected from each positive compartment by means of
pipes pppp (Fig. 2) which are fixed on the lid of each positive compartment and
it is aspirated by a convenient apparatus at the end of the last tank.
The inlet and outlet main pipes which respectively communicate with the anode

page_text: and cathode compartments are disposed either in the upper, or in the lower o
central parts of the tanks, as I find it more suitable, according to the arrangemen
adopted for the tanks which may be in one or two, or more rows, on the same level
or which may be disposed "in cascade" in series of 4 or 5 tanks (each row slightly
over the other).
In order to control the regularity of the flow of the positive and negative
electrolytes, two glass gauges can be placed in the upper part of each positive and
negative compartment.
My compartments are narrow; the electrolytic action is therefore at its maximum
since between two carbon anodes in each positive compartment, and two metallic
cathodes in each negative compartment, the layer of circulating liquid is very thin
and thus the resistance is at its minimuin.
The cathodes, not being as thick as the anodes, I may have the negative com-
partments narrower than the positive ones, so that about the same quantity of
liquid is electrolysed while travelling through the positive and the negative
compartments; the above arrangement allows me to have a much greater surface
of electrodes than is usual in ordinary electrolytic apparatuses.
Parallel to the chlorine pipe P runs a metallic or other convenient pipe of a
larger size than the chlorine pipe which serves to carry off the hydrogen which is
evolved in the negative compartment and which is aspirated at a proper speed by a
convenient apparatus in an opposite direction to that of the current of the chlorine
gas. In order to make the drawings less complicated, the negative compartments
are shown without lids, and the pipes for leading off the hydrogen are not shown.
Each main pipe is provided at one end with a cock for withdrawing the liquid,
with a view to taking samples and to ascertaining whether there is any chlorine in
the alkaline lye or hypochlorite or chlorate in the positive compartments; but, the
porosity of the diaphragm being very great, the cocks of the positive compartments
are not situated on the same side as those of the negative compartments and thus
the flow of the liquids being in an opposite direction there is no possibility of
infiltration or percolation between the chlorinated and alkaline solutions.
My anodes vary according to the purpose for which I use the electrolytic tank.
For instance, in the production of oxygen from a sulphuric acid solution, the
positive plates will be made of lead or peroxide of lead; they will be made of iron
or steel in a solution of soda or caustic potash. In other cases, they will be made
of platinum, or in electro-plating operations, they will be made of the metals to be
deposited. In the present example of the electrolysis of a chloride of sodium
solution, my anodes will consist of slabs of retort carbon.
The best and perhaps the only material which can serve as anodes in the
electrolysis of halogens, is the well-known gas retort carbon, but I could not claim
its use in an electrolytic tank if it were not that I utilize in a new and efficient
manner, retort carbon which otherwise cannot be obtained in large slabs, and
therefore is practically unavailable.
Another difficulty is to connect the carbon anodes together and with the dynamo
without exposing the metallic contacts to corrosion by chlorine and oxygen. My
device however which I will hereafter describe allows me to utilize retort carbon
as auodes in the most efficient manner.
My invention does not consist in the use of retort carbon but in a novel mode of
construction which allows me to utilize it at the positive pole in the commercial
production of chlorine and caustic soda by electrolysis or in similar electrolytic
operations. My tank being shallow, I can easily find pieces of carbon long enough
to be used as anodes and even to touch the bottom of the tank. The mode of
construction is as follows; Out of the raw pieces of scurf I cut slabs of a con-
venient size (Figs. 2 & 24, Plate 11) which at the top corners, show two shoulders
leaving a protruding piece which after being rounded off or not, is fitted into a hole
cut in the slate lid as shown (Figs. 3 & 4, Plate 11).
Fig. 1, Plate 11, shows the lid of a positive compartment with holes cut, through
which will pass the heads of the anodes. These holes are first internally coated

page_text: with a cement made of litharge, powdered asbestos porous porcelain and convenient
agglutinating material or with any other convenient cement to keep the anodes
firmly in position.
It will be understood by reference to Fig. 4 that whatever may be the length of
my anode compartments, it is easy to make anodes of a sufficiently large surface.
The carbon pieces are carefully ground on the side which faces the cathodes, from
which they are only separated by a thin asbestos or kieselguhr porous porcelain
diaphragm, but the other side does not require to be carefully planed.
"C
66
"
a is
In the upper part of the carbon anodes (Figs. 2 & 2ª, Plate 11) a groove
cut and the top of the carbon anode "" (which in the drawing is shaded) is
coppered and tinned, so that contact bars of a convenient size may be fixed on it.
shows a small hole through which a hard wood peg boiled in paraffin is forced.
Round the groove "a" made in the neck of the anode I wind a paraffined string
or cord "d" so as to prevent the carbon from being loose and also gas from
escaping from the positive compartment. When this collar made of paraffined
string has been firmly tied, I coat it with a layer of paraffin or other insulating
material to make it quite an impervious mass through which no gas can escape.
Fig. 3, Plate 11, shows two anodes in cross section, each in presence of a porous
partition A A close to the other side of which is the corresponding cathode B B.
From the close proximity to the electrodes presenting a large active surface, the
thinness of the porous diaphragm and of the intervening layers of rapidly flowing
electrolyte, the resistance is reduced to a minimum.
The porous diaphragms which are generally used in electrolytic operations are
made of clay, asbestos, cardboard or cloth, nitrocellulose or vegetable parchment ;
I replace such porous diaphragms by some others which oppose but little resistance
and which from the point of view of cheapness, durability and efficiency are
excellent in electrolytic installations.
The new diaphragms I adopt for my electrolytic tanks are made of asbestos
porous porcelain, or pumice stone porous porcelain alone; or they may be made of
kieselguhr porous porcelain or a porcelain consisting of pulverized pumice stone
mixed with powdered asbestos, infusorial earth or other substances which resist
gases, alkalis, or acids.
These porous porcelain plates, especially the asbestos porcelain or the kieselguhr
porcelain, being made of nearly unattackable substances and baked at a high temper-
ature resist acids, alkalis, and even chlorine, oxygen, and caustic soda incomparably
better than the best ordinary porous clay or porcelain which very rapidly
disintegrates and allows the diffusion of the liquids.
By preference, I use asbestos porous porcelain as a diaphragm in the shape of
plates A A Fig. 3, Plate 11, which I fix on slate, porcelain, ebonite or insulated
wood frames, placed in a groove cut in the sides and bottom of the tank where they
form water-tight compartments.
The closeness of the electrodes is very favourable to the good yield of the
electrolysis. As may be seen in Fig. 3, Plate 11, the result of this disposition of
electrodes and of the diaphragms, is that there are two similar electrodes in each
compartment, i.e. two carbons in each positive and two cathodes in each negative
compartment, working much more satisfactorily than if one anode and one cathode
only were in each compartment. The electrodes and porous porcelain partitions
are therefore in the following order in the tanks ;-carbon anode, diaphragm,
metallic gauze cathode, metallic gauze cathode, diaphragm, carbon anode, carbon
anode, and so on.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The construction of electrolytic tanks provided as above described with main
and branch pipes for the inlet and the outlet of the liquids circulating respectively
in and out of the positive and negative compartments, so as to maintain regular

page_text: flows of the chlorinated and alkaline solutions through a series of electrolytic
tanks.
2. The above described and illustrated device for the construction and arrange-
ment of anodes presenting large surfaces, made up of single pieces of retort carbon
passed through the covers of the compartments and externally connected together
and with the dynamo, as above described.
3. The use of porous diaphragms such as asbestos, porous porcelain or kieselguhr
or pumice stone porous porcelain, disposed between the cathodes and the anodes
placed near to each other, substantially as above described.
4. The arrangement of electrodes placed close to each other, separated by a thin
diaphragm and a thin layer of electrolyte only, thus providing two similar
electrodes in each positive and negative compartment.
5. The arrangement consisting of a slate or other frame supporting the
diaphragm, fixed in a groove m the sides and bottom of the tank, and facing which
are placed or fixed on one side the anode, and the cathode on the other.
6. The above described manner in which the chlorine gas and hydrogen are
aspirated from their respective compartments, in opposite direction.
7. In an electrolytic tank, the combination of main and branch pipes through
which the chlorinated and the alkaline solutions circulate with their corresponding
positive and negative compartments formed by means of asbestos porous porcelain
or equivalent porous porcelain, and disposed each between a perforated or metallic
gauze cathode and a retort carbon anode in such a manner that there are two
anodes in each positive compartment and two cathodes in each negative com-
partment substantially as herein before described.
London. 28th June 1893.
EMILE ANDREOLI.