Improvements in and relating to Electrolytic Apparatus.
Year: 1893

page_text: Date of Application, 22nd Aug., 1893-Accepted, 21st Oct., 1893
COMPLETE SPECIFICATION.
Improvements in and relating to Electrolytic Apparatus.
[Communicated from abroad by LA SOCIÉTÉ OUTHENIN CHALANDRE FILS & CIE.,
of 95, Boulevard Beaumarchais, Paris, France.]
I, DAVID YOUNG, Patent Agent, of the Firm of D. Young & Co.,
11 & 12 Southampton Buildings, London, W.C., 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 an improved electrolytic apparatus chiefly designed for
the electrolysis of sea-salt or chloride of sodium with a view to the simultaneous
production of caustic soda in solution and of chloride of lime in the form of powder
or liquid, and in the latter case free from sea-salt. The improved apparatus may,
moreover, be employed for all operations of the same class, that is to say, for the
electrolysis of any other compounds or materials.
In the accompanying drawings:-
Figure 1 is a side elevation partly in vertical longitudinal section, and
Figure 2 a transverse section of the improved apparatus.
Figure 3 is a plan of the same, a part of the cover being removed.
Figure 4 is a sectional elevation showing details of the arrangements employed
for mounting the tubes.
Figure 5 is a vertical section showing a salt tank.
The vat which encloses the apparatus is composed of an external fluid-tight
It is constructed
tank K, Figure 1, containing the electrolyte and the electrodes.
of suitable material which cannot be attacked by the liquid which it contains, or it
may be protected by the application of a suitable varnish.
The dimensions of the said tank are slightly greater than those of the compart-
ment containing the anodes and the cathodes, which it has to enclose, and will
correspond, in every case, with the magnitude of the output which it is desired to
provide for. It is, in fact, the magnitude of the output which determines the .
dimensions and the number of electrolytic cells to be employed, the said cells
being joined up either in series or in parallel, according to the circumstances of
the case.
The cathodes are of metal, such as wrought or cast iron for example, which is
not attacked by the electrolyte, in the case of sea-salt.
Their arrangement is hereinafter described in connection with the compartment
containing the carbon or platinum anodes. The total electrode surface is pro-
portioned to the work to be done.
The compartment containing the anodes, getting aside the various openings which
are formed therein, to be hereinafter described, is so constructed as to form a fluid-
tight chamber, the sides or walls of which are held together by external metallic
bolts and does not contain any bare metallic parts in its interior which are capable
of being attacked by the gases or liquids therein. The plates forming the sides
and bottom of the chamber are formed of ebonite, glass, porcelain, or earthenware.
These materials may be employed alone or in combination.
-
The said anode chamber or compartment is essentially composed of two
plates A and B perforated with orifices, such as o and o¹, shown in section more
clearly in Figure 4. On the internal surfaces of the said plates are formed :-
1st, grooves or rabbets arranged to receive the side plates C and D, and the
bottom F; and 2nd, holes for the passage of the external screw-threaded rods or
bolts 6 which serve to hold the parts of the chamber together. The joints are

page_text: made fluid-tight, either by means of bands of india-rubber or by suitable cement
placed in the grooves of the plates A and B. The joint around the bottom F
and sides C and D is made tight in a similar mauner, by means of grooves r¹,
Figure 1, provided with india-rubber or cement, and external bolts . This joint
may be arranged in other ways than that shown, but the method of construction of
the joints should be always the same in this respect, viz. :-that the bolts are always
external to the chamber or compartment containing the anodes. In the event of
the chamber being of such dimensions that the perforated plates A and B are in
several parts, it is possible, according to the material used for the plates A and B,
to brace them at their upper portions by tubes T, Figure 1, enclosing bolts or
screw-threaded rods having external nuts.
Between the ends of each tube T and the internal surfaces of the plates A and B
are placed india-rubber washers which prevents the gases or liquid in the anode
compartment, from penetrating to the interior of the tube T (which is likewise
formed of unattackable material, such as ebonite, glass, or the like) and corroding
the rod or bolt 6". The tightening of the external nuts on each rod or bolt ensures,
at the same time, the tightness of the ends of the tubes T and the bracing of the
plates A and B. It is thus possible, for example, to provide as many braces as there
are rows of tubes.
These
The cover G (of glass, porcelain, ebonite, or the like) Figure 1, hermetically
closes the anode chamber at the top by means of india-rubber or cement inserted
between the top of the four vertical walls of the chamber and the under side of the
cover, the whole being held in position and secured by external bolts.
holding-down bolts, in sufficient number, may be secured under the four vertical
walls of the chamber; or under the walls A and B only, and upon the upper
rods b, balong the sides C and D. The said holding-down bolts may be otherwise
arranged, but, whatever be the arrangement chosen for the attachment of the said
bolts for securing the cover G, they should be always external to the anode
chamber.
The openings o and o' in A and B, are arranged in vertical and parallel rows,
opposite to each other in pairs, their axes being slightly inclined to the horizontal
as shown in Figures 2 and 4.
These openings are adapted to receive diaphragms formed of tubes of thick
porcelain or other material of suitable perosity, and of round or flatened section,
open at both ends.
The method of mounting these tubes is shown in detail in
Figure 4. In certain cases, the flattened section is more advantageous with
regard to compactness of arrangement and electrical resistance.
Each porous tube P, Figure 4, is introduced into one of the orifices o of the
side A, the diameter of which orifice is slightly greater than that of the tube.
The tube Prests against a flexible india-rubber washer R' placed at the base of
the corresponding orifice o' in the plate B. A second india-rubber washer R is
then placed on the other end of the tube P, in the orifice o of the plate A. On
this washer rests the broad base of a kind of stamped and perforated bridge-piece
through the centre of which passes, the hooked bolt S which is secured to the
corresponding cathode arranged in the tube P, as hereinafter described. By means
of the winged nut on the bolt S, the whole is secured in the base of the orifice o' in
such a manner as to slightly compress the india-rubber washers and ensure fluid-
tightness of the joints between the tube and the plates which support it. All the
porous tubes are fixed in the same manner, the liquid in the anode chamber being
thus separated from the liquid contained in the external tank K, herein before
described, without mixture of the said liquids; the electrical connection being
provided for by the porosity of the diaphragm. The position of these tubes in the
tank, is such that they are all completely covered by the electrolyte. The method
employed for mounting these porous tubes, greatly simplifies their replacement or
renewal in case of need; and ensures their perfect fluid-tightness when replacement
or renewal is necessary. The tubular arrangement of the diaphragms is conducive
to their strength and durability, which can be further increased by reason of their

page_text: relatively large surface which allows them to be made less porous without unduly
increasing their electrical resistance.
The anodes are arranged vertically between two rows of the porous tubes, as
shown at I, Figures 1 and 2. They are made of carefully prepared carbon, in the
form of rods or plates, sealed into a bar or head U, Figure 2, of lead or other
suitable material cast in a suitable mould. The said heads extend slightly beyond
the carbons at each end so as to form shoulders which support the anode by resting
on the bottom of grooves n, n, formed in the plates A, B for this purpose. The
lead bars or heads U are arranged to be at a certain distance above the level of.
the liquid, in which they should not be immersed. The application of a suitable
varnish, such as one made from bitumen or gum lac is sufficient to protect the metal
of the anode heads against the action of the gases filling the space above the liquid
in the anode chamber.
Each anode head or bar is provided with an external terminal for receiving
current from the circuit, which terminal consists of a screw-threaded rod t partly
cast into the metal. This rod passes through the cover G. The portion of the
lead bar or head near the lid is provided with a flexible india-rubber washer.
In order to ensure the tightness of the anode chamber at this point, the said
washer is gripped by means of a screw-threaded cap or closed nut è screwed upon
the rod t. The said cap is so formed as to leave a certain space between the top of
the screw-threaded rod and the closed end of the cap, to permit the tightening up
of the same; this cap, moreover, forms the terminal, as it is provided, in a well-
known manner, with a mercury-cup on its upper surface, in which rests a lug g
formed on the main conductor, which is joined to the corresponding pole of the
dynamo electric machine or other suitable source of electricity. This arrangement
allows the condition of the connections to be ascertained at any moment. The
anode terminals are all in the same line and are arranged on the opposite side to
where the cathode terminals are joined to the source of electricity.
The cathodes consist of bands or sheets of iron for example, of suitable section,
and shaped as shown in dotted lines at J Figure 4. Their larger surfaces
are parallel to the planes of the anodes. Their width is somewhat less than the
internal diameter of the porous tubes P into which they pass freely. They are
inserted by the orifices o of the plate A; the notch in the end passes loosely over
the rod Figure 4, and, when the small opening passes out beyond the plate B, a
key or pin is inserted, which pin bears against the outer face of the plate B, when
the bolt S is tightened as above described to close the joints at the ends of the porous
tubes, the hooked bolt S engaging with the small aperture S¹ formed in each
cathode. The stress is thus borne by the plate B when the joints of the tubes P
are tightened up. The replacement of a cathode, or its removal to permit the
insertion of a porous tube is therefore very easily performed.
The connection of the cathodes with the corresponding pole of the dynamo
electric machine is effected by means of the notches at one of their extremities
engaging with screw-threaded metal rods arranged parallel to the plate B,
opposite to each horizontal row of tubes P. Each rod is, moreover, provided with
as many pairs of nuts and metal washers as there are cathodes. These nuts and
washers are previously placed on the rods and screwed approximately into position,
leaving a sufficient space between the washers opposite each tube to allow the
cathodes to be placed in position as above described. It is not until the cathodes
are placed in position and the joints of the tubes tightened up, that the said nuts
and washers are screwed home on each side of the notch in the cathodes which ride
on the rods, (see the first three rows, Figure 1). All the horizontal rods may be
joined to a single conductor, by solder or otherwise and this main conductor is
connected to the corresponding pole of the dynamo electric machine, outside the
liquid.
An alternative method of connection may be employed, whereby all the cathodes
in each vertical or horizontal row are made in one piece of either cast or wrought

page_text: iron. Each piece thus resembles a kind of comb the teeth of which enter the
corresponding tubes and the back of which extends out of the liquid, as shown at M,
to form the electrical connection with the main external conductor. (See Figure 2
and the last two rows in Figure 1.)
In order that the cathodes may be cast or forged in a single piece, they are
inserted by the aperture o¹ in the plate B, each cathode having two projections
abutting against the plate B and replacing the cross-bar or pinj employed with the
shaped strips or sheets. The opposite end of each tooth of the comb-shaped piece
is provided with an aperture, as in the case of the strips, to receive the hooked
bolt S as above described.
According to the circumstances of each particular case one or the other of the
above arrangements may be adopted. The first may be disadvantageous for use with
certain liquids, the connections of each cathode being in the electrolyte, but it is
simpler than the second when considering the removal of single plates which may
have to be effected. Whichever it be, the principle remains the same in so far as
relates to the support of the cathodes by the tightening of the joints of the porous
tubes. The arrangement of the anodes is thus, in either case, dependent on the
anode chamber, and, with it, the said anodes form a whole which, if necessary, may
be withdrawn after emptying the outer tank K for cleaning, examination or repair.
The anode chamber may be provided with handles or eye-bolts according to its size
to facilitate handling.
From the cover G extends the pipe H for the escape of any gases which may be
liberated during the operation of the apparatus. The apparatus may also be fitted
with a thermometer to indicate the temperature of the electrolyte in contact with the
anodes; a manometer tube to control the pressure of the gases above the sid
electrolyte a gauge-glass to show the level of the liquid, and other suitable
accessories. The cover is preferably provided with two tubes, suitably joined
thereto, shown with arrows, Figure 1, and designed to maintain a given concen-
tration of the electrolyte in the interior of the chamber. This concentration is
obtained by mechanically circulating the electrolyte through an independent tank
containing the salt to be treated. This tank is formed of glass, porcelain, or the
like, or other material which cannot be attacked by the liquid it is to contain. It
is divided into two unequal compartments by a vertical partition joined to a double
perforated bottoni, Figure 5. It is also hermetically closed by a cover having a
hydraulic joint which permits the introduction of salt into the larger compartment a
when necessary. The liquid drawn from the upper part of the electrolyte by one of
the tubes passing through the cover G arrives by the pipe 1 and must pass through
the salt placed in the space a and be strengthened before returning by the pipe 2.
The tank is so situated that the liquid running off through the pipe 2 flows
naturally by means of the second tube (passing through the cover G) which leads
it to the lower part of the anode chamber. In order to prevent an accumulation of
gases in the free space above the liquid in the salt tank, this space is connected by
a small pipe with the escape pipe H extending through the cover of the anode
chamber.
The above description refers exclusively to details of construction and arrange-
ment characterizing the improved electrolytic apparatus. The industrial operation
thereof is hereinafter described, taking as an example the electrolysis of sodium
chloride. The electrolytic decomposition of this salt liberates or produces :-
1st. A solution of pure caustic soda free from sodium chloride. 2nd. An evolution
of chlorine, and products containing chlorine and oxygen, capable of being employed
in the manufacture of chloride of lime in the form of liquid or powder, or else the
production under certain conditions of chlorites, chlorates, and other compounds of
chlorine with various bases.
On commencing operations, the anode chamber being placed in the outer tank K,
the apparatus is filled to the proper height as follows:-The anode chamber is
filled with a saturated solution of salt up to such a level as to cover the tubular

page_text: diaphragms without immersing the bars or heads of the carbons; and the free
space in the outer tank is filled with water to which a small quantity of soda may
be added in order to decrease the initial resistance.
On closing the circuit from the dynamo electric machine in any convenient
manner to the electrolytic apparatus, the separation of the elements of the salt will
immediately commence and the normal working be established in a few moments.
The action of the electric current in the decomposition of common salt is well
known and need not be further described. It is only necessary to state that the
decomposition-takes effect at the same time, both upon the salt and upon the water
which serves as a vehicle therefor.
At the cathode, there will then be an evolution of hydrogen proceeding from the
decomposed water electrolytically, and also chemically by the free sodium which
produces a solution of caustic soda, without admixture of salt, at a higher or lower
degree of concentration. On the solution of soda arriving at the desired strength,
it is drawn off at o, Figure 2, the corresponding supply of water entering at Q.
The inclination of the porous tubes facilitates the disengagement of the hydrogen,
which almost all passes off at the side A; arrangements may be made for collecting
this gas if desired, which arrangements consist in applying and fixing against the
plate A a kind of partition V, Figure 2, extending down into the liquid and covering
all the orifices through which a continuous stream of gas will pass by the
perforated bridge-pieces herein before described. This partition, with the plate A,
forms a removable gas-tight chamber from which the gas may be removed and
stored in any convenient manner. In the upper part a manometer tube may be
provided to indicate the pressure; in the same way the tube supplying water for
maintaining the concentration and the level of the liquid in the outer tank may pass
into this removable compartment. This water gradually runs through the tubes at
the same time becoming rich in soda.
At the anode, there is an evolution of oxygen from the water, and of chlorine
from the salt. These gases pass away as they are generated by the pipe H which
is connected to absorption chambers containing hydrate of lime in powder, or milk
of lime serving for the production of hypochlorite of lime. The rate of evolution
of gas may be indicated by means of a manometer tube as herein before mentioned.
This evolution continues regularly whilst the concentration of the salt in the .
electrolyte remains constant in the anode chamber. It is necessary to maintain
the level of the liquid in the anode chamber by adding water from time to time to
replace that decomposed by the action of the current, the level of the liquid being
observed by means of the aforesaid gauge glass.
The improved apparatus has the advantages, amongst others, of affording a large
area of electrode surface in a small space, and great facility for examination and
repair, all parts being of the same form repeated, and of enabling the electrolysed
elements to be completely separated.
It is obvious that the construction of the improved apparatus can be somewhat
modified without departing from the nature of the said invention.
Having now particularly described and ascertained the nature of my said inven-
tion 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 :-
In an electrolytic apparatus such as is hereinabove described, applicable to the
treatment of all materials capable of being treated by electrolysis:-
First. The peculiar construction of the fluid-tight anode chamber, with external
fastenings, and of the materials above mentioned or other suitable materials.
Second. The use of tubular porous. diaphragms, of any convenient form in
transverse section, of porcelain, earthenware, or other suitable material, and
characterized by the method of mounting the same, in which are placed the
cathodes and which, whilst permitting electrical communication, prevent the liquid
in the anode chamber or compartment from passing into the outer or cathode tank
or vat.

page_text: Third. The above described method of mounting the anodes with their terminals,
in such a manner as to ensure fluid-tightness of the anode chamber.
Fourth. The above described method of mounting the cathodes.
Fifth. The removable compartment secured to the anode chamber, for the purpose
of collecting the hydrogen.
Sixth. The employment of a separate or independent tank or vat to maintain a
uniform degree of concentration of the liquid in the anode chamber.
I further claim the application of the improved electrolytic apparatus to the
treatment of sea-salt or chloride of sodium for the purpose of producing, on the one
hand, a solution of caustic soda, without admixture of the salt under treatment,
and, on the other hand, products containing chlorine and oxygen directly appli-
cable to the manufacture of hypochlorites of lime, chlorites, chlorates, and análogous
compounds.
Dated the "ond low of A wenst 1002
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.