Compounds of Alkalies.
Year: 1887

page_text: Date of Application, 2nd May, 1887
Complete Left, 28th Feb., 1888
Complete Accepted, 2nd May, 1888
and Compounds of Alkalies.
I JULIUS MARX of Ehrenstein near Ulm /Donau Wurtemberg in the Empire
of Germany Chemist do hereby declare the nature of this Invention to be as
follows:-
My Invention has for its object to provide an improved process or means for
the manufacture by electrolysis of alkalies from alkaline compounds i.e. the salts
with an alkaline basis. I will explain my Invention as applied to the manufacture
of soda (either caustic soda carbonate of sodium or bicarbonate of sodium) from
chloride of sodium or common salt from which its analogous applications will also
be understood.
I subject in a partitioned vessel a concentrated solution of common salt (which
may be kept in a state of concentration) to electrolytic action whereupon caustic
soda is formed and chlorine developed.
The partitions of the said vessel may be of porous or perforated material or
with connecting pipes. The soua may be used as caustic soda-solution or it may
be evaporated when the salt which crystallizes out during evaporation is removed
and dried in the ordinary way or the soda solution may be used to make carbonate
or bicarbonate of soda by the method hereinafter described.
The chlorine developed may be drawn or driven off by a current of nitrogen
gas or air which air may be first deprived of carbonic acid and the said chlorine
may be used for any purpose for which it may be required.

page_text: If chloride of sodium be treated by the electric current the reaction given above
ceases after some time in a lesser or greater degree and therefore results ensue
more or less corresponding to a simple decomposition of water namely the soda
already formed takes up a lesser or greater part of the current.
I. 2 Na OH 2 Na + H2 0 + 0
II. 2 Na + H2O = Na 0+2 H
III. Na U+HU = 2 Na UH
5
The decomposition of Na Cl and the re-decomposition of Na OH taking place
together give rise to a serious drawback as solutions of caustic soda are concen-
trating around the anode where chlorine is evolved so that there is a recombining 10
of both
III. Na U+HU = 2 Na UH
The decomposition of Na Cl and the re-decomposition of Na OH taking place
together give rise to a serious drawback as solutions of caustic soda are concen-
trating around the anode where chlorine is evolved so that there is a recombining 1
of both
At the same time chlorine and soda may be recombined by simple diffusion. These
reactions cause a loss of chlorine and soda and an indirect loss of useful energy
caused by the chemical energy becoming free by the combining of chlorine and soda
which energy is given off as heat or as electricity but this electricity has a reverse
direction to the original one (polarization) therefore a corresponding amount of
electric power is neutralized and developes heat. The aforesaid defects are exceed-
ingly wasteful and means as hereinafter described are employed to obviate these
injurious actions by preventing the caustic soda (or other alkali formed) from
becoming redecomposed by the electric current or from being acted upon by the
bodies involved.
As soon as the soda formed commences to be redecomposed to any considerable
degree by the electric current the electrolysis is discontinued and any acid forming
a salt less soluble than the original one may be introduced into the soda solution when
the salt of that acid will precipitate. Carbonic acid is best employed to form car-
bonate of sodium or the less soluble bicarbonate. The solution is then filtered or
caused to precipitate its solid contents and is afterwards brought up to the original
concentration with chloride of sodium and treated anew by electrolysis and this
process may be repeated as often as desired.
This method will be found to present some inconvenience and I have found it
better to work as a continuous process which may be done as follows:-
The salt solution is placed in spouts or troughs or any convenient vessel divided
through its length by porous or other suitable partitions. There may be any number
of compartments but for clearness of explanation I will suppose there to be but two
one for the cathode and one for the anode. Each anode compartment is combined
with the following anode compartment and each cathode compartment with the
following cathode compartment,

page_text: The solution is compelled by plates in the compartments to ascend and descend
alternately and an electrode is placed in the compartment thereby formed. The
spouts troughs or the like are combined in such a way that if the solution enters
the last compartment by the top it enters the next spout trough or the like at or
near the bottom but if the solution enters the last compartment by the bottom it
enters the next spout trough or the like at the top. By this means a continuous
flow of solution is obtained alternately ascending and descending thereby mixing
itself well and forming in each succeeding compartment a more concentrated
solution.
The solution around the cathode is conducted in an inverse direction to that
around the anode, so that the strongest soda solution is opposite the weakest chlorine
solution and vice versa so that the potential between both solutions is reduced the
polarisation is lessened and the electrical transport of caustic soda to the anode and
likewise loss of soda and chlorine are obviated.
The solution leaving the last cathode compartment runs into the apparatus for
saturation with carbonic acid where its soda is precipitated and it is then brought up
to the original saturation with chloride of sodium and run back whereby mechanical
losses are avoided and the density of the solution is kept constant.
The solution leaving the last anode compartment can be used anew or it can be
run into an apparatus wherein the rest of the chlorine is driven off.
The chlorine evolved in the process as well as the hydrogen are conducted off
by piping passing through the covers or lids above the compartments of the spouts
troughs or the like and leading to gas batteries to produce electricity or for being
utilized for chemical purposes as in the apparatus hereinafter described for the
saturation of lime or other base with chlorine. By these reactions part of the
electricity needed for the process may be produced.
The saturation of the caustic soda with carbonic acid may be done in the known
way or by means of one of the following apparatus.
The carbonic acid is intro-
duced into a porous pipe or vessel which may be made of conducting material
and which is filled with fragments of coke or carbon or some other suitable con-
ducting material. The porous pipe or vessel is immersed in the solution of caustic
soda and it has at bottom an opening for the water trickling through the porous
walls but the carbonic acid gas is kept back whereby a large surface is given
and the combining of carbonic acid and soda instead of giving off heat as usual
will give off electricity which may be conducted off by any suitable means such
as by conducting plates inside and outside the porous vessel to form the two poles.
Instead of introducing the carbonic acid into the porous pipe or vessel the latter
may be filled with soda solution then the carbonic acid is introduced into the out-
side vessel which is filled with broken coke. But I prefer to use the following
apparatus.
A vessel is filled (with or without pressure) with carbonic acid.
In this vessel is a series of plates made of conducting material. These plates are
in pairs being in a nearly vertical position but so that one of each pair is kept
against and below the other of the pair. The two plates of each pair are separated
by moistened porous material. The soda solution is kept dropping upon the highest
upper plate and dropping from one upper plate upon the other, the bicarbonate or
carbonate of sodium formed is scraped off or falls off to the bottom where it is
collected. The two plates of a pair form the two poles.
The bicarbonate may be used as such. It can be freed from all foreign matter
by washing.
To transform it into carbonate either the known methods may be used or the
following. The bicarbonate is mixed with a cold solution of caustic soda (the liquor
resulting from the process) and well agitated for a sliort time then it is quickly
filtered or caused to deposit and the solution resulting is now only saturated with
the carbonic acid. The reaction by which the bicarbonate is transformed is as
follows
TTO

page_text: The soda obtained by this means is crystallised soda which by calcining yields a
soda of a dense appearance (resembling the soda of the Le Blanc process) whilst
the soda obtained directly by heating the bicarbonate forms a soda of less dense
appearance (resembling the soda of the "Ammonia Soda" process).
The manufacture of bleaching powder or bleaching liquid may be done accord-
ing to the known methods or in the following manner. To make bleaching liquid
one of the apparatus described for the saturation with carbonic acid may be
employed but to make bleaching powder the following apparatus may be used.
The chlorine is introduced into a revolving vessel containing lime. Its walls are
covered inside with lead or some other conducting substance well insulated from
the inlet pipes.
Part of the chemical energy due to the combination of chlorine
with lime is thereby given off as electricity, the inlet pipe and the walls (insulated
from each other), forming respectively the poles for conducting out this current.
The electricity of the walls is conducted to a ring or disc outside the vessel upon
which metallic brushes or the like slide or the ring revolves upon graphite or
divided metal such as very small metal balls or preferably mercury or a low
melting alloy.
The hydrogen evolved in the process may be used for heating or reducing
purposes or in a gas battery.
This process for the manufacture of alkalies may be recapitulated as follows,
supposing the manufacture of soda from chloride of sodium is being performed.
1) A solution of chloride of sodium is kept running through a series of spouts
so that it alternately ascends and descends. The spouts are divided into two or
more compartments by porous or perforated partitions. The liquor in the anode-
compartments is running in a direction the reverse of that in the cathode-compart-
ment. These liquors are subjected to electrolysis.
2) The liquor running out of the last cathode compartment is a solution of
caustic soda mixed with chloride of sodium. This solution is converted to car-
bonate or bicarbonate of soda by introducing carbonic acid, after filtration the
carbonate or bicarbonate is taken off and the solution is brought up to the original
concentration by chloride of sodium and is run back in the spouts.
3) The chlorine evolved is employed in the usual manner by the known or my
improved apparatus.
4) The liquor running out of the last anode compartment contains mainly a
salt solution saturated with chlorine which may be driven off or the solution may
be run back as such into the spouts.
The hydrogen evolved may be used for any required purpose.
6) The saturation with carbonic acid, the preparation of bleaching powder and
the hydrogen evolved may be used as sources of electricity so that the process itself
produces part of the electricity needed.
It is to be understood that the process above described may be employed to
make soda from other sodium salts as well as from chloride of sodium or to manu-
facture other alkalies or alkaline earths from their salts for example:-
For the manufacture of carbonate, bicarbonate and caustic soda from sulphate
of soda I take a concentrated solution of sulphate of soda and as hereinbefore
described I subject it to electrolysis, caustic soda and sulphuric acid are produced,
the caustic soda is treated as hereinbefore described and the sulphuric acid solution
may be evaporated when sulphuric acid, anhydrous sulphuric acid and bisulphate
of soda will be formed corresponding to the proportions of free sulphuric acid and
sulphate of soda namely:-
:-

page_text: But it is better to take off the sulphuric acid formed by electrolysis as it is
formed by suspending in the liquid round the anode some insoluble oxide or car-
bonate yielding an insoluble sulphate by combination with the acid. If a carbonate
be used there will be evolved carbonic acid to saturate the caustic soda with and
if carbonate of lime be used there will be produced gypsum precipitated in a form
very useful for paper makers.
If potash salts are used instead of soda salts according to the above process
potash or caustic potash will be produced and if chloride of potassium be employed
the chlorine developed may be used to make chlorate of potassium directly from
the caustic potash solution.
When the process is applied to the electrolysis of salts which yield oxides
insoluble or soluble with difficulty as is the case with the alkaline carths it is
only necessary to keep the solution up to the point of concentration to cause the
oxides formed to precipitate, to take out these precipitates continuously or at
intervals and to remove the acids and the like in the
described.
manner hereinbefore

page_text: I JULIUS MARX of Ehrenstein near Ulm Donau Württemberg in the Empire
of Germany 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 :-
My Invention has for its object to provide an improved process or means for the
manufacture by means of electrolysis of alkalies and alkaline compounds (especially
the carbonates and bicarbonates) from the compounds or the salts with an alkaline
base.
It is well known that salts of alkalies may be decomposed by electrolysis but hitherto
it has not been found possible to effect in a practical manner a complete chemical
decomposition of the salts by that means. It is the object of my Invention to provide
a process by which the hitherto existing difficulties are overcome.
I have discovered that the main cause of failure has arisen from the fact that the
products obtained by electrolysis being soluble and conductive by reason of their
solubility they take up part of the electricity and thereby to a greater or lesser
extent effect their own decomposition so that finally the result of the electrolysis
often is simply equal to a decomposition of water and at the same time much electric
energy is wasted.
For example the soluble products obtained from a solution of chloride of sodium
treated by electrolysis become redecomposed if the electrolytic action be continued
over a certain time and the redecomposition of the Na OH then taking place together
with the decomposition of Na Cl gives rise to a serious drawback as during
electrolysis solutions of caustic alkalies are concentrating around the anode, where
chlorine is evolved from the Na Cl so that there is a recombining of both

page_text: Similar reactions will take place round the cathode to which the current transports
some of the chlorine evolved round the anode where likewise Na Cl will be recomposed
either by H Cl or by reduction or it may be directly
At the same time chlorine and soda may be recombined by simple diffusion.
These reactions have all the same tendency and effect viz. they cause a loss of
chlorine and soda and a great waste of the otherwise useful energy in developing the
recombined chlorine and soda. Loss of energy is also caused by the chemical energy
becoming free by the combining of chlorine and soda which energy is given off as
useless heat or as electricity having a reverse direction to that of the original
electricity therefore a corresponding amount of electric power is neutralized
(polarised).
A further very great waste as herein before mentioned is caused by the decom-
position of water brought about by the redecomposition of Na OH.
(I) 2 NaOH = 2 Na + H2O + 0
(II) 2 Na + 2 H2O = 2 Na OH + 2 H.
As soon as these reactions take place the liquor becomes as I have demonstrated
unfit for practical electrolysis and it is likewise unfit for economically recovering the
caustic soda contained therein. This accounts for the failures which have hitherto
resulted from attempts to employ electrolysis for the manufacture of alkalies and
compounds of alkalies.
Having found that the cause of failure is due to the solubility of the products
obtained by electrolysis, I according to my invention render the otherwise soluble
products of electrolysis insoluble or at least soluble with difficulty before or at the
time of their becoming so concentrated as to act or to be injuriously acted upon as
hereinbefore stated.
I will describe my invention as applied to the manufacture of soda from chloridė
of sodium (or common salt) from which its analogous applications will also be
understood. My process is not dependent upon any special apparatus as any vessel
adapted for clectrolytical purpose will answer the purpose but I prefer to use a vessel
divided by permeable partitions into a pair or pairs of compartments in which
I submit to electrolytic action a solution of common salt (Na Cl) which may be kept
concentrated, whereupon caustic soda is formed and chlorine developed.
I. 2 Na Cl + 2 H20= 2 Na + 2 H2O + 2 Cl
ON
១ ប
ON OH
NOH
OH
As the production by electrolysis of caustic soda is going on and before or at
latest as soon as it commences to be redecomposed by the electric current to any
considerable extent. I add to the caustic soda solution any suitable acid, forming a
salt less soluble than the original salt from which the soda was produced. Carbonic
acid being the cheapest will be found the most suitable. By introducing sufficient
carbonic acid into the solution it effects the precipitation of the caustic soda by
forming bicarbonate of sodium. This bicarbonate is removed from the solution and
the solution is then preferably brought up to its original concentration by adding
thereto more chloride of sodium and the electrolysis being thereafter continued all
the salt can be eventually completely used.

page_text: In order to render the process a continuous one and to minimise as much as
possible the polarisation by the recombining products a reverse circulation is caused.
The vessel containing the salt solution may be divided into any number of pairs of
compartments. Or any desired number of separate vessels each containing a pair or
several pairs of compartments can be used. One compartment of each pair contains
the anode and the other compartment contains the cathode. Where several com-
partments are provided each anode compartment is combined with the next anode
compartment and each cathode compartment is combined with the next cathode
compartment for allowing the solution to flow from each into the other.
The solution is caused to flow or circulate with an equal or a differing velocity
through the several compartments in a reverse direction that is to say, the solution
is conducted around the anodes in a direction the reverse of that in which it is
conducted around the cathodes so that the strongest soda solution is opposite the
weakest chlorine solution and vice versa by which reverse direction of flow or
circulation the potential between both solutions is reduced and therefore the tendency
to recombination and mechanical transport by the current are lessened and thus
unnecessary loss of soda and chlorine are obviated.
The liquors thus flowing in a reverse direction to each other, the solution leaving
the last cathode compartment of the series runs into an apparatus for saturation with
carbonic acid wherein the caustic soda is precipitated as bicarbonate of soda, and the
solution is then preferably brought up to the original saturation with chloride of
sodium and is then run back again for treatment by electrolysis. The solution
leaving the last anode compartment may be used again or it may be run into an
apparatus where the remaining chlorine is taken off. But as this solution gets richer
in chlorate of sodium which is formed by the presence of oxygen as above explained
it is better to run the solution slowly enough to allow precipitation of the chlorate,
which is effected by adding to the solution chloride of potassium, whereupon the
original salt will regenerate. To absorb the small part of chlorine remaining in the
solution a small quantity of an alkaline substance (preferably caustic soda) may be
added to the potash salt. After precipitation the anode liquor likewise runs back
into the electrolytical apparatus being if necessary saturated anew with chloride of
sodium.
The chlorine developed may be used to make bleaching liquid or for any purposes
for which it may be required and to facilitate the development the said chlorine may
be drawn off or may be driven off by a current of nitrogen gas or of air first deprived
of carbonic acid.
As mentioned the electrolysis causes the formation of caustic soda which may be
used as caustic soda solution or it can be concentrated to obtain solid caustic soda,
but I do not consider such a course preferable, as the liquor can be advantageously
used in the process according to my invention.
The hydrogen evolved by the electrolysis may be used for any purpose to which it
is or may be adapted.
The bicarbonate produced, having no odour, may be used as such after washing or
it may be transformed into carbonate. But the soda obtained- directly by heating
the bicarbonate is not of a dense appearance and so is not suitable for use in some
processes but I obtain from the bicarbonate a dense soda resembling the soda of the
Leblanc process as follows
I transform the bicarbonate into carbonate by mixing it with caustic soda when
the following well known reaction takes place
Na H CO + NaOH = Na* CO + HO

page_text: water, or with soda solution. The carbonate being formed has not time. to dissolve
and being crystallized yields after calcination a very dense soda.
The filtered liquor may be saturated with carbonic acid and treated according to
the system hereinbefore described.
.
Instead of employing a vessel divided as herein before described, separate baths
connected by pipes may be employed, or narrow troughs may be formed by arranging
frames like the frames, of a filter press. The apparatus as before stated may be of
any suitable description but it should allow the solutions to flow round the cathodes―
in a direction the reverse of that in which it flows round the anodes, so as to reduce
the tendency to re-combining as hereinbefore explained.
It is to be understood that the process hereinbefore described for making soda from
chloride of sodium may be employed to make soda from other sodium salts or to
manufacture other alkalies or. alkaline compounds from alkaline salts. For example,
with Sulphate of Sodium (Na² SO) a solution (preferably a concentrated solution)
of sulphate of soda is treated as hereinbefore described..
The electrolysis produces caustic soda and sulphuric acid. The caustic soda is
treated as hereinbefore described, but the sulphuric acid may likewise be taken off by
rendering it insoluble. Acting with this object therefore upon the principle of
making soluble products less soluble, I may suspend round the anode a suitable
insoluble carbonate like carbonate of lime, whereby carbonic acid is produced to
saturate the caustic soda with and gypsum is precipitated in a form very useful for
use in paper making.
Or the solution round the anode may be evaporated and calcined when sulphuric
acid anhydrous sulphuric acid, hydrochloric acid and Bisulphate or Pyrosulphate of
sodium are formed corresponding to the amount of chloride, sulphate and sulphuric
acid left in the solution.
I. H' SO + 2 Na CI = Na³ SO* + 2 H Cl
II. Na SO + H2SO4
= 2 Na H SO*
III. 2 Na H SO₁ = Na³ SO SO3 + H2O
IV. Na SO SO3 = Na³ SO* + SO³.
This new process may be worked with acids or bases other than those named or
with the compound of another base yielding soluble products by electrolysis. If
potash salts instead of soda salts be treated according to the hereinbefore described
process, the electrolysis produces caustic potash thus potash and caustic potash can be
manufactured.
If chloride of potassium be employed the chlorine developed may serve instead of
carbonic acid to precipitate the potash. Thus chlorate of potash may be made
directly from the caustic potash solution.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is :-
:-
1. The manufacture of alkalies and compounds of alkalies from the salts of the
alkalies or from compounds of the salts of the alkalies by subjecting a solution of the
salt or compound to electrolytic action, and before or at the commencement of
redecomposition of the products adding an acid or a halogen forming a salt less
soluble than the salt first subjected to electrolytic action substantially as and for the
purpose hereinbefore described.
2. In the manufacture of an alkali or the compound of an alkali by means of
lectrolysis from the salts of the alkalies or from compounds of the salts of the
lkalies to be made subjecting the solution of the salt or compound to electrolytic
ction in a vessel through which the solution is caused to flow round the cathodes in
direction the reverse of that in which it flows round the anodes substantially as and
or the purpose hereinbefore described.
3. The manufacture of carbonate and bicarbonate of sodium or potassium by

page_text: subjecting a solution of chloride sulphate or other soluble salt of sodium or of
potassium (or such salt which has been rendered soluble) to electrolytic action
whereby caustic soda or potash and chlorine or sulphuric acid (or the corresponding
acid) will be formed then adding to the alkaline solution carbonic acid whereby the
soda or potash will be precipitated as Bicarbonate of Soda or potash and transforming
the said Bicarbonate into dense Carbonate by quickly mixing with caustic alkali and
immediately separating it after mixing as hereinbefore described.