Improvements in Apparatus for and in the Method of Making Caustic Alkali and Sodium.
Year: 1898

page_text: Date of Application, 12th Aug., 1898
Complete Specification Left, 10th May, 1899-Accepted, 24th June, 1899
DIONAL DI MULTICATION.
Improvements in Apparatus for and in the Method of Making Caustic
Alkali and Sodium.
I, JOHN CAMERON GRAHAM, of 2, Garden Court, Temple, Barrister, do hereby
declare the nature of this invention to be as follows:-
The invention relates to an improved apparatus and methods for the preparation
of sodium and caustic alkalies by causing the sodium to be thrown down
electrically from any suitable solution such as chloride of sodium, onto a moving
mercury cathode whereby an amalgam of sodium and mercury is formed from
which the sodium can be extracted in a metallic form or caustic alkali produced
by allowing the amalgam to come into contact with water.
The apparatus preferably consists of a shallow trough having a bottom slightly
inclined, over which mercury is allowed to flow in a continuous stream.
The mercury acts as the cathode and the solution of salt lies in the trough
immediately over the mercury and is caused by means of a pump to circulate
rapidly over the mercury preferably in the opposite direction to that in which
the mercury flows. Over or in the electrolyte, are the anodes which may form
the top of the trough and are so placed as to come as near as possible to the
mercury thereby diminishing the internal resistance of the apparatus to a
minimum.
With this arrangement the current density may be very materially increased
over that usually employed without producing any material quantity of hydrogen
or oxygen, the production of which is usually a dead loss of electrical energy.
The method of causing the electrolyte to circulate over the cathode has already
been published in the Specification of Letters Patent No. 8410 of 1896 granted to
me.
The mercury is introduced into the trough by a suitable pipe and the amalgam
passes out through a further pipe by which it may be conducted into a vessel
where it may be decomposed into caustic alkali and mercury. The mercury may
be circulated by means of a pump.
The chloride of sodium or other electrolyte is caused to flow with considerable
rapidity through the trough between the anodes and the cathode, and from there
into a suitable chamber where it may be resaturated or otherwise treated and
again passed through the decomposing chamber. The chlorine gas is led off and
utilized for the manufacture of bleaching powder or for other purposes.
By the means described the sodium in the electrolyte which is on the face of the
cathode as a chloride is continuously renewed so that there is at all times a path
for the current through sodium molecules in consequence of which the current
density may be made very much higher than by any process now used: where
no circulation of the electrolyte is used the sodium in the solution on the cathode
surface becomes rapidly exhausted and the current having no path through sodium
molecules begins to pass through water molecules and to generate hydrogen on
the cathode.

page_text: The resistance of the electrolyte to the passage of the current may be reduced
by adding some salt such as sulphate of soda without otherwise affecting the
results materially.
Or
The sodium may be recovered from the amalgam in any known manner.
as before mentioned the amalgam may be decomposed in water and caustic alkali
produced by allowing the amalgam to come into contact with water. A convenient
method of doing this consists in allowing the amalgam to flow into a chamber
containing one or more sieves, through the meshes of which the amalgam will
fall in small streams through the water, thereby largely increasing the area of
the amalgam which comes in contact with the water; or the amalgam surface
exposed may be increased by allowing the amalgam to flow down a series of
zig zag inclined planes which are immersed in water. Or this may be effected by
means of a number of discs of say thin wrought iron placed near together on a
revolving shaft, and arranged so as to dip into the amalgam each disc carrying
a thin film of mercury round with it, the amalgam approaching more and more
to the condition of pure mercury as it approaches the outlet of the vessel in
which the discs revolve. And if the water in which the amalgam is decomposed
be warmed to a considerable temperature it will hold much more caustic alkali in
solution than it can do at ordinary atmospheric temperatures, and the caustic
alkali will crystallize out as soon as the temperature is allowed to fall.
Several of the troughs may be placed one over the other or side by side so that
the circulating electrolyte may be caused to flow through several of such troughs
in succession, or if preferred the circulation of the electrolyte may be obtained by
causing it to flow through tubes by which it is directed in the form of jets against
the face of the mercury cathode, the mercury being caused to circulate in any
convenient manner.
1001
1000
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicant.
Improvements in Apparatus for and in the Method of Making Caustic
Alkali and Sodium.
I, JOHN CAMERON GRAHAM, of 2, Garden Court, Temple, Barrister, 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 invention relates to an improved apparatus and methods for the preparation
of sodium and caustic alkalies by causing the sodium to be thrown down
electrically from any suitable solution, such as chloride of sodium, onto a moving
mercury cathode whereby an amalgam of sodium and mercury is formed from
which the sodium can be extracted in a metallic form or caustic alkali produced
by allowing the amalgam to come into contact with water.
The apparatus preferably consists of a shallow trough having a bottom slightly
inclined over which mercury is allowed to flow in a continuous stream.
The mercury acts as the cathode and the solution of salt lies in the trough
immediately over the mercury and is caused by means of a pump to circulate

page_text: rapidly over the mercury, preferably in the opposite direction to that in which
the mercury flows. Over or in the electrolyte, are the anodes which may form
the top of the trough and are so placed as to come as near as possible to the
mercury thereby diminishing the internal resistance of the. apparatus to a
minimum.
With this arrangement the current density may be very materially increased
over that usually employed without producing any material quantity of hydrogen
or oxygen, the production of which is usually a dead loss of electrical energy.
The method of causing the electrolyte to circulate over the cathode has already
been published in the Specification of Letters Patent No. 8410 of 1896 granted
me.
The mercury is introduced into the trough by a suitable pipe and the amalgam
passes out through a further pipe by which it may be conducted into a vessel
where it may be decomposed into caustic alkali and mercury. The mercury may
be circulated by means of a pump.
The chloride of sodium or other electrolyte is caused to flow with considerable
rapidity through the trough between the anodes and the cathode, and from there
into a suitable chamber where it may be resaturated or otherwise treated and
again passed through the decomposing chamber.
The chlorine gas is led off and utilized for the manufacture of bleaching powder
or for other purposes.
By the means described the sodium in the electrolyte which is on the face of the
cathode as a chloride is continuously renewed so that there is at all times a path
for the current through sodium molecules in consequence of which the current
density may be made very much higher than by any process now used, where
no circulation of the electrolyte is used the sodium in the solution on the cathode
surface becomes rapidly exhausted and the current having no path through sodium
molecules begins to pass through water molecules and to generate hydrogen on
the cathode.
The resistance of the electrolyte to the passage of the current may be reduced
by adding some salt such as sulphate of soda without otherwise affecting the
results materially.
Or
The sodium may be recovered from the amalgam in any known manner.
as before mentioned the amalgam may be decomposed in water and caustic alkali
produced by allowing the amalgam to come into contact with water.
Several of the troughs may be placed one over the other or side by side so that
the circulating electrolyte may be caused to flow through several of such troughs
in succession, or if preferred the circulation of the electrolyte may be obtained by
causing it to flow through tubes by which it is directed in the form of jets against
the face of the mercury cathode, the mercury being caused to circulate in any
convenient manner.
In this apparatus the electrolytic cell does not move, nor does it contain any
moving parts, all the movements of the fluids being effected by ordinary external
pumps and by the action of gravity.
In the accompanying drawings
Figs. 1 and 2 show a very convenient form of apparatus.
Fig. 1 is a longitudinal section of the apparatus, and
Fig. 2 a transverse section on the line A B in Fig. 1.
C are the carbon anodes. H the space between the anodes and the cathode
through which the solution to be electrolyzed is caused to flow. D is a metallic
bed over which the mercury flows. The mercury is introduced at E from which
point it flows down the inclined bed and escapes at F. The chloride of sodium
solution is introduced through the pipe G, and escapes together with all the
chlorine which has been generated through the pipe J.
There is very little recombination of the sodium in the mercury with the water
of the electrolyte above it so long as the current is made to pass from the anode
through the electrolyte to the mercury cathode.

page_text: Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
1. In the manufacture of caustic alkali or sodium amalgam enclosing the anodes
and cathodes in a chamber through which both the electrolyte and the mercury
are caused to flow, substantially as described.
2. The improved apparatus for the manufacture of sodium amalgam, in which
both the mercury and the electrolyte are caused to circulate, substantially as
described and as shown in the accompanying drawings.
Dated this 10th dow of M 1800
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicant.