Improvements in the Method of and Means for Separating Matters in Solution by Osmose, Dialysis or Diffusion, or by Electrolysis, or by a Combination of those Processes.
Year: 1888

page_text: Improvements in the Method of and Means for Separating Matters
in Solution by Osmose, Dialysis or Diffusion, or by Electrolysis,
or by a Combination of those Processes.
I, JULIUS MARX, of Ulin "/ Donau, Württemberg, in the Empire of Germany,
Chemist, do hereby declare the nature of this invention to be as follows:-
This Invention relates to the method of and means for separating matters in,solution
by osmose, dialysis or diffusion or by electrolysis or by a combination of those
processes.
In the said processes the soluble bodies sooner or later cause a stoppage of the
process by reason of the solubility of these soluble bodies and I have devised means
for making these processes continuous and complete by removing the prime cause
of the evil i.e. the said solubility and this I effect by precipitating the soluble bodies
after the reaction has commenced, but before the reaction could be stopped again by
the increasing accumulation in the solution of these soluble bodies.
In the specification of my application for patent No. 6417 of 2nd May 1887 1
have described the influence of such soluble bodies in the electrolysis of alkaline and
similar salts and a plan of obviating the defect by the simple and direct addition of
an acid forming a salt less soluble than the salt originally electrolysed.
My present invention relates to the employment of that process for the precipitation
of dialysed bodies, and also to means for and the mode of application of those means
to processes by osmosc-electrolysis of treating compounds yielding soluble products
under electrolytic action and my Invention refers further to the combination of both
these processes.
I use the terms " osmose ""dialysis" and "diffusion" in the same sense and to
facilitate description I call that liquor or solution which becomes filled with the
substance to be dialysed the "filling liquor" or solution and I call that liquor or
solution which keeps the dialysed substances dissolved (or whatever would keep the
dialysed substances dissolved) if I did not precipitate these substances the "solvent
liquor" or solution.

page_text: L
:
J
I will explain firstly my invention as applied to osmoses.
The separation of the different substances of a solution by osmose is a troublesome
operation as hitherto performed or proposed to be performed. To overcome the
hitherto existing difficulties I precipitate the bodies intended to be obtained by osmose
as far as possible as they enter into the "solvent" liquor, so that the dialysed body
is kept from supercharging the "solvent" solution and if the substance to be dialysed
be readded in proportion as it leaves the "filling" solution the latter cannot become
less concentrated.
1. The difference between the two liquors remains practically the same throughout
the process.
2. By reason of that constant difference the same velocity occurs throughout the
process.
3. The process may be interrupted or may be continued as long as desired.
4. The substances to be dialysed are employed practically completely.
In working the process of osmose two points are to be observed viz. :-the reagent
serving to precipitate must act upon the substance to be precipitated beyond the
amount of its having diffused into the "solvent" liquor and the substance to be
dialysed is best added free of water as it is less convenient to add it in solution.
2:
The substance to be dialysed may be contained in a bag, basket, perforated through
or the like before putting it into the " filling liquid to keep it supplied with the
substance to be dialysed, or such substance may be introduced mechanically the
amount introduced being regulated as desired. The process becomes then a very
simple and easy one, there being nothing left to be done but to supply into the
"filling" liquor the substance to be dialysed and into the "solvent" liquor the
precipitating substance and recover the precipitate. All these operations can be done
mechanically and thus labour be minimised to the utmost.
The operation is not so conveniently performed if the substance to be dialysed be
employed in solution, as in the case for example of sugar solutions, molasses, brines
and the like. But these also may be freed from their contents more easily by my
invention than by the methods hitherto used. By judiciously choosing the precipitating
agent and by arranging a series of dialytical compartments, the products may be
obtained separately which is another advantage of my invention. The solutions are
dialysed either intermittently by filling the apparatus, dialysing completely at once,
a series of
emptying after operation and refilling or continuously by combining
apparatus causing the solution to flow through and concentrating it, again if need be
after it leaves the last apparatus. The reconcentrated solution is then run back or
mixed with the original solution.
The precipitation may be effected by an acid forming a salt less soluble than the
one originally operated on, as referred to in the electrolysing process described in my
before named Specification but a compound may be used, which decomposes with such
substance by making it insoluble or soluble with difficulty, such as bicarbonate of
magnesium with caustic soda, or a compound may be used which combines with the
substance to be precipitated by forming an insoluble or difficultly soluble mixed
compound such as the carbonate of sodium and magnesium.
Another way, as hereinafter described, is to form such compound from its component
in the solution itself.
By precipitating after one of these methods not only the osmotic process but also
the electrolysis of compounds which yield soluble products under electrolytic action
will be continuous.
The process I prefer is one in which the osmose is combined with electrolysis and
the electrolytic products may be let off continuously or the osmose may be worked
along with electrolysis assisted by my precipitating method and I shall now give a
example to show how this operation may be performed.
I have chosen as example the decomposition of chloridle of sodium because that sal
is very common and serves to show all three phases of my invention at once, each
alone and clearly each in its connection with and influence upon each other. Fron

page_text: this a Chemist will readily understand the small alterations to be made for working
other products by my process which mainly will consist in the employment of another
precipitating reagent. I do not confine myself to chloride of sodium nor to the other
sodium or potassium salts, as any substance capable of being dialysed or electrolysed
yielding thereby soluble products may be treated by my process by choosing the proper
precipitating reagent.
The process may be carried out in any suitable apparatus, but I have provided some
improvements in apparatus for the purpose which will much. facilitate or perfect the
process and which may be used alone or be combined with the apparatus hitherto
used.
Having provided a suitable vessel it is divided by three permeable walls into four
compartments. The two middle compartments contain the electrodes and I call them
"Electrode-Compartments." One being for the anode and the other for the cathode.
The two end compartments are intended to receive the products of the osmose and
electrolysis and I call these compartments "Osmose-Compartments."
The whole apparatus is now filled with salt solution and in the electrode-compartment
is suspended a bag, basket or perforated trough or the like kept filled with salt and
then the electric current completed through the solution. Chlorine and caustic soda
are developed and diffuse into the osmose compartments where they are precipitated
and then a further quantity diffuses in and as long as the precipitation_is
kept up, the osmose continues and as long as the osmose is kept up, the
electrolysis goes on properly, and as long as the electrolysis is kept up the
dissolution of fresh quantities of salt continues. Therefore all that has to be
done is, to close the electric circuit, to supply the salt as it becomes dissolved, and to
remove the precipitate. But this very simple process may be still further simplified.
The supply of the salt is easily made by mechanical means, and may then be regulated
to keep up any convenient strength of the solution, likewise the adding of the precipi-
tator and the taking out of the precipitated substance may easily be done mechanically,
so that nearly no manual labour has to be done and supervision is minimised to the
utmost.
The strength of the solution is best kept somewhat below complete saturation
because such a solution has the best conductive power.
The whole apparatus being filled with the same solution of salt and the solution
being kept the same strength all through no salt can diffuse but only the other soluble
products, namely, chlorine and caustic soda.
.
The chlorine is developed for the most part as gas, which will be led off and used
for any desired purpose, another smaller part being dissolved and diffused in the
osmose-compartiment and in the anode-compartment where it is precipitated as chlorate
of potash or it may be used to make peroxide of lead or otherwise. By using the
reagents in excess to combine with chlorine the dissolved part of chlorine is increased,
whilst by passing a current of air or other suitable gas round the anode through the
solution or by using suction the gaseously developed part of chlorine is increased
and in this case the osmose-compartment and the anode-compartment may be
disused.
The caustic soda diffuses in the osmose-compartment as well as the cathode-
compartment and is there precipitated either by adding an acid forming a salt soluble
with difficulty or by adding a salt of such acid which yields its acid to the sodium.
The cheapest will be carbonic acid but its employment offers two inconveniences.
First, to saturate a solution with a gas requires either a long time or high pressure,
secondly the precipitating reagent cannot be added but in the proportion of the
diffusion of the substance to be precipitated, provided that reagent be not insoluble
like for example carbonate of lime to precipitate sulphuric acid. But it is very difficult
to add a gaseous soluble substance like carbonic acid in such a way, that its amount
accords exactly with that of the dialysed body.
All these inconveniences are obviated by the following process. Into the osmose-
compartment is put magnesia (hydrate, oxide or carbonate) and then only the carbonic
acid is introduced. The absorption of the carbonic acid then goes on very readily and

page_text: completely without pressure for the gas is absorbed by the magnesia in so far as the
caustic soda cannot combine with it quickly enough.
The process is preferably conducted long enough to prepare the badly soluble mixed
Carbonate of Sodium-Magnesium.
A surplus of magnesia does no harm.
The method just described can be used for many purposes especially for the manu-
facture of potash because of the bicarbonate of potash not being very insoluble at
ordinary temperatures. As it is clear, the latter process consists in adding a substance
which acts like a reservoir and transmitter. It stores up the surplus of gas not being
fit for immediate use and transmits it later to the substance to be saturated. Therefore
any other similar acting substance may replace the magnesia and any similar acted on
substance may replace the caustic soda, be the saturating gas carbonic acid or other
gas and time power and expensive apparatus are saved.
But there is another advantage in the process. The mixed alkaline carbonates of
magnesia are easily decomposed by caustic alkali by heat, or boiling or by passing
steam through them and in the latter cases by regulating the steam or water the
solution of carbonate may be obtained of any strength for example to obtain directly
soda crystals. The carbonic acid is easily recovered by the decomposition itself and
the magnesia is fit to be used over and over again.
To prevent rotable dialysing from the anode-compartment to the cathode-compartment
the walls between these two compartments should be somewhat less permeable than
the walls separating the electrode-compartments from the osmose-compartments or
preferably the hereinafter described means are employed.
To work another salt such for example as sulphate of Potassium, I proceed as
before but into the osmose-compartment beside the anode compartment is put (for
instance) carbonate of lime, when gypsum will precipitate and carbonic acid will be
developed.
It will be clear now that the salient feature of the new process does not reside in
any particular form of apparatus but in the proper combination of osmose with
precipitation, electrolyses with precipitation or osmose, electrolysis and precipitation
processes, but notwithstanding that, some improvements in the apparatus may be
employed which I have found very useful.
It is a long felt deficiency that the permeable walls necessary for asmose and for
certain kinds of electrolysis prove inconvenient. The resistance of diaphragms is not
always the suitable one, and their manufacture is difficult as is the case for instance
with large porous thin clay-plates. Then again the diaphragms become rapidly
deteriorated which is the case with parchment paper and further the materials suited
for the porous plates or vessels are very limited and that alone accounts for much of
the want of use of dialysis in the arts.
All these drawbacks I obviate by constructing these permeable walls in the following
manner.
Rods, sticks, pipes or the like of any diameter and any shapo (for example, round,
elliptical, square, three cornered or like strips or ribbons) and of any material are put
together one above the other or one beside the other and are kept in place at the ends
by insertions in grooves in a stand, or frame or the like, so that they form a wall of
which the joints are close enough to prevent, if the wall be placed in a liquid
communication from side to side except by diffusion. Such walls have the further
advantage of easily allowing increase or decrease of permeability. The permeability
is augmented if many thin rods or the like are used or if the rods and the like are

page_text: applied not quite close together. The permeability is diminished if a few thick rods
or the like be used, if they be slightly pressed together or if there are applied (with or
without spaces between each wall) several such walls together or if the joints of each
wall be placed reversely to each other.
Two or more such walls may likewise be so arranged that the rods of each wall
cross those of the other wall or walls.
The rods or the like may have any shape as may also the walls formed by them.
For instance to build vessels with round walls each rod may be closed forming a ring,
which rings are then superposed or a rod may be wound in a spiral, each convolution
touching the adjacent ones and having the diameter of the vessel required or the
rods may be arranged in a circular series kept together by rings or a circular
frame.
In place of making the walls of rods, perforated plates can be used, which are
superposed with or supported behind each other, the openings in one not coinciding
with those in the adjacent ones.
The diffusion by such walls is brought about mainly through the medium of
capillary attraction between the surfaces arranged near together.
The layers of liquid formed by this capilliary action themselves constitute good
diaphragms and so liquids, if properly applied, may be used as diaphragms and the
construction of such "liquid diaphragms" is very simple. Their offect is a very high
one and nothwithstanding their good separating power they offer a small resistance
which is most important, because of its permitting a much greater useful effect for
electrolytic purposes.
It is the best to make the "liquid diaphragms" as thin as possible. It may be
very narrow if the liquid thereof is employed but for simple separation. It must
become larger if it is intended to carry a solid reagent or if precipitates are formed
there.
To make such liquid diaphragms the vessel is divided by two walls made from any
material, provided it resists the action of the solutions. These two walls are put near
together. The two walls should not only be very porous but preferably they are even
perforated by small openings such as holes, slits or the like, for their only object is to
contain between them the liquid which constitutes the real diaphragm.
The liquid between these walls may be the same as the solution under operation, or
it may carry a reagent, combining with one or more of the products obtained by
electrolysing chloride of sodium for example to keep the diffusing chlorine back, it.
may carry lime, or other suitable substance, or two such diaphragms may be used one
stopping chlorine, and the other caustic soda: By the slow diffusion of the surrounding
liquids the intermediate liquid between the walls gets deteriorated and it must therefore
be renewed either intermittingly or by continuously flowing through.
These "liquid" diaphragms allow likewise profitable use to be made of the osmatic
effect of the electric currents for example, in electrolysing caustic alkalies the alkalies
concentrate against the anode, therefore they may be precipitated there, or two liquid
diaphragms are placed one behind the other, when the caustic alkali is precipitated in
the one, and the diffusing chlorine is taken off in the other.
For the same purpose an intermediate compartment with permeable walls can be
used be the walls solid or liquid as in reality the intermediate compartment would be
but a large liquid diaphragm.
"
These liquid diaphragms prevent likewise the dialysing between the electrode-
compartment, namely the caustic soda (for example) formed diffuses first equally to
both sides, but being precipitated on the side of the osmose compartment it diffuses
then only there. The small quantity of chlorine diffusing into the liquid diaphragm
is neutralised by the caustic alkali, and is afterwards run off and such small quantity
of caustic alkali must be replaced by means of renewed diffusion. By employing two
liquid diaphragms that quantity is further reduced.
To recapitulate the main essential feature of the invention is to precipitate
systematically by chemical means the soluble products which by their accumulation
would stop osmatic and electrolytic processes and to effect by such combined process

page_text: results, not so easily or not so completely to be got by the hitherto employed means.
The processes as hereinbefore shewn are combined, osmotico-precipitating electro-
lytico-precipitating and electrolytico-osmotico-precipitating.
The process not being dependent upon any special apparatus allows me to employ
or easily to adapt the usual apparatus and to simplify it by the introduction of a
chemical reagent acting like a reservoir, or a transmitter as herein before described,
and by means of the walls of rods or the like and the "liquid" diaphragms each
alone or all combined the apparatus is simplified supervision is reduced and labour,
time, and power are economized.

page_text: Improvements in the Method of and Means for Separating Matters
in Solution by Osmose, Dialysis or Diffusion, or by Electrolysis,
or by a Combination of those Processes.
I JULIUS MARX of 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 :-
This Invention relates to the method of and means for separating matters in
solution by osmose (dialysis or diffusion) or by electrolysis or by a combination of
these processes.
In the said processes as hitherto conducted the soluble bodies sooner or later cause
a stoppage of the process by reason of the solubility of these soluble bodies and I
have devised means for making these processes continuous and complete by removing
the prime cause of the evil i.e. the said solubility and this I effect by precipitating the
soluble bodies after the reaction has commenced but before the reaction could be
stopped again by the increasing accumulation in the solution of these soluble bodies
and the effect of this new process is the greatest if the precipitation be done by
measure of the diffusion or production of these soluble bodies.
In the Specification of my application for Patent No. 6417 of 2nd May 1887 I have
described the influence of such soluble bodies in the electrolysis of alkaline and similar
salts and likewise a plan of obviating the defect by the simple and direct addition of
an acid forming a salt less soluble than the salt originally electrolysed.
My present invention relates to the employment of that process for the precipitation
of dialysed bodies and also to means for and the mode of application of those means
to processes by osmose and electrolysis for treating compounds yielding soluble
products under electrolytic action and my invention refers further to the combination
of both these processes.
.
"
I use the terms osmose dialysis" and "diffusion as having the same meaning
and to facilitate description I call that liquor or solution which becomes filled with the
substance to be dialysed that is which contains it in solution the "filling liquor" and
I call that liquor or solution which keeps the dialysed substances dissolved (or which
would keep the dialysed substances dissolved if I did not precipitate these substances)
the "solvent liquor."
I will explain firstly my invention as applied to osulose.
The separation of the different substances of a solution by osmose as hitherto
performed or proposed to be performed is a troublesome operation. To overcome the
hitherto existing difficulties I precipitate the bodies intended to be obtained by osmose
as far as possible as they enter into the "solvent liquor" so that the dialysed body is
kept from concentrating in the "solvent liquor" and if the substance to be dialysed be
readded in proportion as it leaves the "filling liquor" the latter cannot become less
concentrated thus :-
1. The difference between the "filling liquor" and the "solvent liquor" remains
practically the same throughout the process.

page_text: 2. By reason of that constant difference the process proceeds at the same rate
throughout.
3. The process may be interrupted as often and may be continued as long as
desired.
4. The substances to be dialysed are practically completely utilized.
It is very important for a successful working to see that the reagent serving to
precipitate does not act upon the substance to be precipitated beyond the amount
of its having diffused into the "solvent liquor" and if it be possible to add the
substance to be dialysed in a solid form it will prove more convenient than to add
it in solution.
If solid the substance to be dialysed may be contained in a bag, basket, perforated
trough or the like suspended in the "filling liquor" so as to keep it supplied with
the substance to be dialysed or such substance may be introduced mechanically the
amount introduced being regulated at will as required. The process becomes in
such case a very simple and easy one, there being nothing left to be done but to
supply into the filling liquor" the substances to be dialysed and into the "solvent
liquor" the precipitating substance and to recover the precipitate. All these operations
can be done mechanically and thus labour can be miniinised to the utmost.
"
The operation is not quite so conveniently performed if the substance to be dialysed
be employed in solution as in the case for example of sugar solutions, molasses
brines and the like. But these also may be freed from their contents more easily
by my invention than by the methods hitherto used. The solutions are dialysed either
intermittently by filling the apparatus dialysing completely at once emptying after
the operation and refilling or they can be dialysed continuously by combining a
series of apparatus causing one or both solutions to flow through and concentrating
the " filling solution
again if need be after it leaves the last apparatus. The
reconcentrated solution is then run back or mixed with the original solution.
Another advantage of my invention is that by judiciously choosing the precipitating
agent which will be evident to Chemists each component of a mixed compound may
be obtained separately. For this purpose it is but necessary to arrange a series of
dialytical compartments e.g. A vessel be divided into three compartments and filled
with water. If now pieces of sugar-beets be introduced into the first compartment its
soluble compounds are diffusing into compartment No. 2 where lime is added thus
to precipitate Sulphuric and Phosphoric acid or parts of them when likewise some
organic impurities are precipitating. The sugar thus partly purified is diffusing into
compartment. No. 3 where it is precipitated by baryta in the known manner.
saccharate of baryta thus obtained being already partly purified is easier to work
for manufacturing sugar.
The
By similar means mixed salts are treated to recover their different components
separately.
But the precipitation may be effected by an acid forming a salt less soluble than the
one originally operated upon as referred to in the electrolysing process described in
my before named Specification but likewise a compound may be used which
decomposes or combines with such substance by making it insoluble or soluble with
difficulty such as bicarbonate of magnesium with caustic soda or as baryta with
sugar or a compound may be used which combines with the substance to be pre-
cipitated by forming an insoluble or difficultly soluble mixed compound such as the
carbonate of sodium and magnesium.
Another way as hereinafter described is to form such compound from its component
in the solution itself.
By precipitating after one of these methods not only the osmotic process but also
the electrolysis of compounds which yield soluble products under electrolytic action
will be made continuous.
The process I prefer for electrolysing is one in which osmose is combined with
electrolysis when the electrolytic products may be led off continuously or the osmose
may be worked along with electrolysis assisted by my precipitating method and 1
shall now give an example to show how this operation may be performed.

page_text: I have chosen as an example the decomposition of chloride of sodium because that
sult is very common and because it can serve to show all three phases of my inven-
tion at once, each alone and each in its connection with and influence upon the
others. From this a Chemist will readily understand the small alterations to be
made for working other products by my process which alterations mainly will consist
in the employment of another suitable precipitating reagent I do not confine myself to
chloride of sodium nor to the other sodium or potassium salts as any substance capable
of being dialysed or of being electrolysed (and yielding by electrolysis soluble
products) may be treated by my process by choosing the proper precipitating
reagent.
The process may be carried out in any suitable apparatus but I have provided some
improvements in means or apparatus for the purpose which will much facilitate or
perfect the process and which may be used alone or be combined with the apparatus
hitherto used as they may readily be adapted to them.
Having provided a suitable vessel it is divided by three. permeable walls into four
compartments. The two middle compartments contain the electrodes and I call them
"Electrode-Compartments" the one being for the anode and the other for the cathode
and I call them respectively the "anode compartment" and the "cathode compart-
ment." The two end compartments are intended to receive the products of the
osmose and electrolysis and I call these compartments "Osmose Compartments."
I further calling the "osmose compartment" connected with the anode compartment
the " anosmose compartment" and the osmose compartment connected with the
cathode compartment the "cathosmose compartment."
The whole apparatus is now filled with solution of chloride of sodium and in either or
both of the electrode compartments is suspended a bag basket or perforated trough or
the like kept filled with chloride of sodium and then the electric current is passed through
the solution. Chlorine and caustic soda are developed & diffuse into the osmose com-
partments, where they are precipitated and then a further quantity diffuses in and as
long as the precipitation is kept up the osmose continues and as long as the osmose is
kept up the electrolysis goes on properly, and as long as the electrolysis is kept up the
dissolution of fresh quantities of salt continues. Therefore all that has to be done is,
to close the electric circuit, to supply the salt as it becomes dissolved, and to remove
the precipitate. But this very simple process may be still further simplified. The
supply of the salt is easily made by mechanical means, and may then be regulated to
keep up any convenient strength of the solution, likewise the adding of the precipitator
and the taking out of the precipitated substance may easily be done mechanically, so
that nearly no manual labour has to be done and supervision is reduced to the
utmost.
The strength of the solution is best kept somewhat below complete saturation
because such a solution has the best conductive power.
The whole apparatus being filled with the same solution of salt and the solution
being kept the same strength all through no salt can diffuse but only the other soluble
products, namely, chlorine and caustic soda.
The chlorine is developed for the most part as gas, which may be led off for
manufacturing bleaching powder, or chlorates, or organic chlorides, or it may be used
for bleaching purposes, or to be liquefied or in fact it may be employed for any desired
purpose. Another smaller part being dissolved diffuses in the anosmose compartment
where it may be precipitated as chlorate of potash or it may be used to make peroxide
of lead or otherwise, for example the solution may be made to serve for bleaching.
By using in excess reagents which combine with chlorine the dissolved part of
chlorine is increased at will whilst by passing a current of air or other suitable gas
round the anode through the solution or by using suction the quantity of chlorine
developed as gas is increased. If the chlorine is to be led off as gas, the anosmose
compartment may be dispensed with.
The caustic soda diffuses into the cathosmose-compartment and tends at first to
diffuse into the anode compartment, but as the caustic soda diffused into the cathosmose-
compartment is precipitated continuously it preferably diffuses toward that side, as
R

page_text: there the solution
kept the poorest in caustic soda. Or the resistance of the
diaphragm between the two electrodes might be made somewhat greater than the
resistance of the diaphragm between the cathode-compartment and the cathosmose-
compartment.
To precipitate the caustic soda carbonic acid is the cheapest and the drawbacks
accompanying that operation may be greatly reduced by proceeding as follows:-Into
the cathosmose-compartment is put magnesia (hydrate, oxide, or carbonate) and then
only the carbonic acid is introduced. The absorption of the carbonic acid then goes
on very readily and more completely than without magnesia for the gas is largely
absorbed by the magnesia in so far as the caustic soda cannot combine with it
quickly enough.
The process is preferably conducted long enough to produce the badly soluble mixed
carbonate of sodium-magnesium.
A surplus of magnesia does no harm.
The method just described can be used for many purposes especially for the
manufacture of potash. The bicarbonate of potash not being very insoluble at ordinary
temperatures the precipitation of caustic potash by carbonic acid is very incomplete
or very troublesome. As it is clear in employing magnesia the improvement resides
in adding a substance which acts like a reservoir and transmitter. As it stores up the
surplus of gas not fit for immediate use and thereafter transmits it to the substance to
be saturated. Therefore any other similar acting substance may replace the magnesia
for example hydrate of zinc and any substance similar acted on may replace the
caustic soda for example caustic potash be the saturating gas carbonic acid or other
gas for instance sulphurous acid gas and time, power, pressure and expensive apparatus
are saved.
But there is another advantage in the process. The mixed alkaline carbonates of
magnesia formed in the process are easily decomposed by caustic alkali or by heat, a
most suitable way is to pass superheated steam through or over them and then by
regulating the steam and water the solution of carbonate may be obtained of any
strength for example to obtain soda crystals directly. The carbonic acid is easily
recovered and by the decomposition itself the inagnesia is obtained fit to be used over
and over again or by employing for example Carnallit for electrolysing magnesia may
be manufactured.
To prevent or reduce potable dialysing from the anode-compartment to the cathode-
compartment the walls between these. two compartments should be somewhat less
permeable than the walls separating the electrode-compartments from the osmose-
compartments or preferably the hereinafter described means. are employed.
To work for example a salt such as sulphate of potassium, I proceed as before but
into the osmose-compartment next to the anosmose-compartment (for instance)
carbonate of lime, when gypsum will precipitate, and carbonic acid will be developed.
The oxygen is led off from the anode-compartment and the carbonic acid from the
anosmose-compartment and thus both gases are obtained separately. The carbonic
acid may serve for saturating purposes, and the oxygen for use in lighting.
Instead of carbonate of lime, phosphate of lime may be employed, when an acid
phosphate will be obtained very suitable as manure, especially if it be mixed with
sulphate of potassium. Or the phosphate monocalcic may be prepared and by the
addition of the caustic potash formed by electrolysing sulphate of potassium a very
good fertilizer of a double phosphate of potassium and calcium is to be obtained..

page_text: Or a chloride (for example chloride of calcium) may be added when the sulphuric
acid becoming free will precipitate again as gypsum yielding hydrochloric acid suited
for lixiviating or extracting ores.
It will be clear now that the salient feature of the new process does not reside in
any particular form of apparatus but in the proper combination of osmose with
precipitation, electrolysis with precipitation or osmose-electrolysis with precipitation
processes, but notwithstanding that, some improvements in the apparatus may be
employed which I have found very useful and which easily are adapted to the usual
apparatus.
It is a long felt deficiency that the permeable walls necessary for osmose and for
certain kinds of electrolysis prove inconvenient. The resistance of diaphragms is a
given but not always a suitable one, and their manufacture is difficult as is the case
for instance with large porous thin clay plates. Then again the diaphragms become
rapidly deteriorated which is the case with parchment paper and further the kind of
materials suited for the porous plates or vessels are very limited and that alone
accounts in a great measure for dialysis not having been more extensively used in
the arts.
All these drawbacks I obviate by constructing these permeable walls or partitions
in the following manner.
Rods, sticks, pipes or the like of any diameter and any shape (for example, round,
elliptical, square, three cornered or like strips or ribbons) and of any material capable
of resisting the action of the surrounding liquids are put together one above the other
or one beside the other and are kept in place at the ends by insertions in grooves, in a
stand, or frame, or the like, so that they form a wall of which the joints are close
enough to prevent, if the wall be placed in a liquid, communication from side to side
except by diffusion. Such walls have the further advantage of easily allowing increase
or decrease of permeability. The permeability is augmented if many thin rods or the
like are used or if the rods and the like are applied not quite close together. In
the latter case preferably strips or ribbons are employed. The permeability is
diminished if a few thick rods or the like be used, if they be slightly pressed
together or if there be applied (with or without spaces between each wall) several such
walls together, especially if the joints of each wall be placed so that they do not
coincide with each other.
Two or more such walls may likewise be so arranged that the lengths of their
component rods or the like cross each other or so that the rods or the like of one wall
cross those of the other wall or walls or one wall may have its joints in a horizontal
direction and the next one in a vertical or diagonal direction.
The rods or the like may have any shape as may also the walls formed by them.
For instance to build vessels with round walls each rod may be closed forming a ring,
which rings are then superposed or a rod or a number of rods and the like may be
wound in a spiral, each convolution touching the adjacent ones and having the
diameter of the vessel required or the rods may be arranged in a circular series
kept together by rings or a circular frame. Square vessels or other shaped vessels
may be similarly constructed.
In place of making the walls of rods, perforated plates can be used, which are
superposed with or supported behind each other, the openings in one not coinciding
with those in the adjacent ones. But these plates I find less convenient. These
openings may be regulated by mechanical devices.
In employing such walls the diffusion is going on between the joints or openings of
the single parts and the dialytic action is modified and regulated by the capillary
attraction between the surfaces arranged near or close together.
The layers of liquid formed by this capillary action thus constitute the diaphragms
and so liquids if properly applied, may be used as diaphragms and the construction
of such liquid-diaphragms is very simple. Their effect is a very high one and
notwithstanding their good separating power they offer a small resistance which is
most important, because of its permitting a much greater useful effect for electrolytic
purposes.

page_text: Such liquid diaphragms are provided for instance by constructing the permeable
walls described out of broad strips or ribbons, which may leave somewhat open joints.
Another way to make liquid diaphragms is the following.
The vessel is divided by two walls made from any material, provided it will resist
the action of the solutions. These two walls are put near together but leaving a
space between them. The two walls should not only be very porous but preferably
they are even perforated with very small openings such as round holes or slits and
the like or the permeable walls mentioned above are employed when the permeability
may be regulated to suit circumstances.
The only purpose of these two walls is to prevent the liquid between them from
mixing too rapidly with the surrounding liquors, and these two walls are not to cause
such a real interruption as the usual porous diaphragms for, the liquid between them
substitutes the diaphragm.
The liquid between these walls may be the same as the solution under operation, or
it may carry a reagent, combining with one or more of the products obtained by
electrolysing; hydrate of sodium for example to keep the diffusing chlorine back; or
it may carry lime, or other suitable substance, or two such diaphragms may be used
one stopping for example chlorine; and the other caustic soda. By the slow diffusion
of the surrounding liquids the intermediate liquid between the walls gets deteriorated
and it must therefore be renewed either intermittently or by continuously flowing
through of fresh liquid.
These liquid diaphragms allow likewise profitable use to be made of the osmotic effect
of the electric currents, for example in electrolysing caustic alkalies the alkalies
concentrate against the anode, therefore they may be precipitated there; or two
liquid diaphragms are placed one behind the other, when the caustic alkali is
precipitated in the one, and the diffusing chlorine is taken off in the other or the
chlorine and the caustic alkali are made to combine in such a liquid diaphragın
between the two electrodes. Then hypochlorite of sodium for example forms.
By regulating the flow of that intermediate liquid the strength of the solution is
regulated and thus it easily adapted to suit different bleaching purposes. By these
means a strong or a very weak bleaching solution may be obtained and after bleaching
the solution may be re-employed either for electrolysis or only for the intermediate
liquid. Or if no need for bleaching exists, the chlorine or caustic soda may be
employed otherwise as described above. Or during electrolysis greater or smaller
parts of chlorine or caustic soda are employed at the same time and at will either for
bleaching or for manufacturing purposes. It is clear that chlorates can equally well
be obtained by a similar process.
For the same purpose an intermediate compartment with permeable walls can be
used be the walls solid or liquid as in reality the intermediate compartment would be
but a large liquid diaphragm.
These liquid diaphragms prevent likewise the dialysing between the electrode
compartments, namely the caustic soda (for example) formed diffuses first equally to
both sides, but being precipitated on the side of the osmose compartment it diffuses
then only there. The small quantity of chlorine diffusing into the liquid diaphragm
is neutralised by the caustic alkali, and is afterwards run off and such small quantity
of caustic alkali must be replaced by means of renewed diffusion.
By employing two liquid diaphragms that quantity is further reduced.
The main essential feature of the invention is to precipitate systematically by
chemical means the soluble products which by their accumulation would stop osmatic
processes and electrolytic processes where soluble electrolytic products result and to
effect by such combined process results, not so easily or not so completely to be
obtained by the processes or means hitherto employed or proposed. The processes as
herein before shewn are combined, osmotico-precipitating, electrolytico-precipitating,
and electrolytico-osmotic-precipitating processes.

page_text: The process not being dependent upon any special apparatus allows me to employ
or easily to adapt the usual apparatus and to simplify it by the introduction of a
chemical reagent acting like a reservoir, or a transinitter as hereinbefore explained
and by means of the walls of rods or the like and the "liquid diaphragms" each
alone or all combined the apparatus is simplified, supervision is reduced and labour,
time, and power are economized.
It will be understood that the processes can be carried on either at a low or at an
elevated temperature. A partial evaporation or a partial or complete re-saturation
may be effected before, during or after the operations described, and heating or
cooling may be applied before, during or after the said operations.
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. In separating matters in solution by osmose (dialysis or diffusion) or by
electrolysis or by a combination of such processes precipitating the soluble bodies
produced or diffused before or at the commencement of the accumulation of such
soluble products in their solution to prevent the injurious reaction set up by such
accumulation substantially as and for the purpose herein before described.
2. In separating matters in solution by osmose (dialysis or diffusion) or by
electrolysis or by a combination of such processes precipitating the soluble bodies
produced or diffused before or at the commencement of the accumulation of such
soluble products in a system of osmose compartments to obtain separately two or
more of the constituents or components of a solution substantially as hereinbefore
described.
3. In separating matters in solution by osmose (dialysis or diffusion) or by
electrolysis or by a combination of such processes effecting a continuous automatic
operation by firstly the suspension (in a suitable receiver) or by the regulated addition
of the substance to be treated into the liquor to be acted on by osmose (dialysis,
diffusion) or by electrolysis, and by secondly the suspension or by the regulated
addition of the precipitating substance or substances into the liquor containing the
products of the osmose (dialysis, diffusion), of the electrolysis or of the osmose-
electrolysis.
4. In separating matters in solution by osmose (dialysis or diffusion) or by
electrolysis or by a combination of such processes, the combining of osmose, (dialysis,
diffusion) and electrolysis so as to carry off by osmose (dialysis, diffusion) the
products of electrolysis substantially as and for the purpose herein before described.
5. In the combining of osmose (dialysis, diffusion) and electrolysis carrying off by
osmose (dialysis or diffusion) the chlorine and the base formed by electrolysis into
the same osmose-compartment to obtain bleaching liquor or chlorates, substantially as
and for the purpose herein before described.
6. In or for apparatus for the purposes described and claimed the construction or
arrangement of permeable walls in the manner herein before described.
7. In or for apparatus for the purposes described and claimed an arrangement
providing "liquid diaphragms" or partitions substantially as herein before described.
Dated this 17th day of December 1888.

page_text: Specification was, upon the 22nd day of October 1889, Amended under
Sections 18 to 21 of the Patents. Designs, and Trade Marks Act 1882
Date of Application, 16th Feb., 1888
Complete Specification Left, 17th Dec., 1888-Accepted, 22nd Jan,, 1889
Improvements in the Method of and Means for Separating Matters
in Solution by Osmose, Dialysis or Diffusion, or by Electrolysis,
or by a Combination of those Processes.
I, JULIUS MARX, of Ulm Donau, Württemberg, in the Empire of Germany,
Chemist, do hereby declare the nature of this invention to be as follows:-
This Invention relates to the method of and means for separating matters in solution
by osmose, dialysis or diffusion or by electrolysis or by a combination of those
processes.
In the said processes the soluble bodies sooner or later cause a stoppage of the
process by reason of the solubility of these soluble bodies and I have devised means
for making these processes continuous and complete by removing the prime cause
of the evil i.e. the said solubility and this I effect by precipitating the soluble bodies
after the reaction has commenced, but before the reaction could be stopped again by
the increasing accumulation in the solution of these soluble bodies.
In the specification of my application for patent No. 6417 of 2nd May 1887 1
have described the influence of such soluble bodies in the electrolysis alkaline and
similar salts and a plan of obviating the defect by the simple and direct addition of
an acid forming a salt less soluble than the salt originally electrolysed.
My present invention relates to the employment of that process for the precipitation
of dialysed bodies, and also to means for and the mode of application of those means
to processes by osmose-electrolysis of treating compounds yielding soluble products
under electrolytic action and my Invention refers further to the combination of both
these processes.
""
I use the terms " osmose ""dialysis" and "diffusion" in the same sense and to
facilitate description I call that liquor or solution which becomes filled with the
substance to be dialysed the "filling liquor or solution and I call that liquor or
solution which keeps the dialysed substances dissolved (or whatever would keep the
dialysed substances dissolved) if I did not precipitate these substances the "solvent
liquor" or solution.

page_text: I will explain firstly my invention as applied to osmoses.
12
The separation of the different substances of a solution by osmose is a troublesome
operation as hitherto performed or proposed to be performed. To overcome the
hitherto existing difficulties I precipitate the bodies intended to be obtained by osmose
as far as possible as they enter into the "solvent liquor, so that the dialysed body
is kept from supercharging the "solvent" solution and if the substance to be dialysed
be readded in proportion as it leaves the "filling " solution the latter cannot become
less concentrated.
1. The difference between the two liquors remains practically the same throughout
the process.
2. By reason of that constant difference the same velocity occurs throughout the
process.
3. The process may be interrupted or may be continued as long as desired.
4. The substances to be dialysed are employed practically completely.
In working the process of osmose two points are to be observed viz. :-the reagent
serving to precipitate must act upon the substance to be precipitated beyond the
amount of its having diffused into the "solvent" liquor and the substance to be
dialysed is best added free of water as it is less convenient to add it in solution.
The substance to be dialysed may be contained in a bag, basket, perforated through
or the like before putting it into the "filling" liquid to keep it supplied with the
substance to be dialysed, or such substance may be introduced mechanically the
amount introduced being regulated as desired. The process becomes then a very
simple and easy one, there being nothing left to be done but to supply into the
filling liquor the substance to be dialysed and into the "solvent" liquor the
precipitating substance and recover the precipitate. All these operations can be done
mechanically and thus labour be minimised to the utmost.
The operation is not so conveniently performed if the substance to be dialysed be
employed in solution, as in the case for example of sugar solutions, molasses, brines
and the like. But these also may be freed from their contents more easily by my
invention than by the methods hitherto used. By judiciously choosing the precipitating
agent and by arranging a series of dialytical compartments, the products may he
obtained separately which is another advantage of my invention. The solutions are
dialysed either intermittently by filling the apparatus, dialysing completely at once,
emptying after operation and refilling or continuously by combining a series of
apparatus causing the solution to flow through and concentrating it, again if need be
after it leaves the last apparatus. The reconcentrated solution is then run back or
mixed with the original solution.
The precipitation may be effected by an acid forming a salt less soluble than the
one originally operated on, as referred to in the electrolysing process described in my
before named Specification but a compound may be used, which decomposes with such
substance by making it insoluble or soluble with difficulty, such as bicarbonate of
magnesium with caustic soda, or a compound may be used which combines with the
substance to be precipitated by forming an insoluble or difficultly soluble mixed
compound such as the carbonate of sodium and magnesium.
Another way, as hereinafter described, is to form such compound from its component
in the solution itself.
By precipitating after one of these methods not only the osmotic process but also
the electrolysis of compounds which yield soluble products under electrolytic action
will be continuous.
The process I prefer is one in which the osmose is combined with electrolysis and
the electrolytic products may be let off continuously or the osmose may be worked
along with electrolysis assisted by my precipitating method and I shall now give an
example to show how this operation may be performed.
I have chosen as example the decomposition of chloride of sodium because that salt
is very common and serves to show all three phases of my invention at once, each
alone and clearly each in its connection with and influence upon each other. From

page_text: this a Chemist will readily understand the small alterations to be made for working
other products by my process which mainly will consist in the employment of another
precipitating reagent. I do not confine myself to chloride of sodium por to the other
sodium or potassium salts, as any substance capable of being dialysed or electrolysed
yielding thereby soluble products may be treated by my process by choosing the proper.
precipitating reagent.
The process may be carried out in any suitable apparatus, but I have provided some
improvements in apparatus for the purpose which will much facilitate or perfect the
process and which may be used alone or be combined with the apparatus hitherto
used.
Having provided a suitable vessel it is divided by three permeable walls into four
compartments. The two middle compartments contain the electrodes and I call them
"Electrode-Compartments." One being for the anode and the other for the cathode.
The two end compartments are intended to receive the products of the osmose and
electrolysis and I call these compartments "Osmose-Compartments."
The whole apparatus is now filled with salt solution and in the electrode-compartment
is suspended a bag, basket or perforated trough or the like kept filled with salt and
then the electric current completed through the solution. Chlorine and caustic soda
are developed and diffuse into the osmose compartments where they are precipitated
and then a further quantity diffuses in and as long as the precipitation is
kept up, the osmose continues and as long as the osmose is kept up, the
electrolysis goes on properly, and as long as the electrolysis is kept up the
dissolution of fresh quantities of salt continues. Therefore all that has to be
done is, to close the electric circuit, to supply the salt as it becomes dissolved, and to
remove the precipitate. But this very simple process may be still further simplified.
The supply of the salt is easily made by mechanical means, and may then be regulated
to keep up any convenient strength of the solution, likewise the adding of the precipi-
tator and the taking out of the precipitated substance may easily be done mechanically,
so that nearly no inanual labour has to be done and supervision is minimised to the
utmost.
The strength of the solution is best kept somewhat below complete saturation
because such a solution has the best conductive power.
The whole apparatus being filled with the same solution of salt and the solution
being kept the same strength all through no salt can diffuse but only the other soluble
products, namely, chlorine and caustic soda.
The chlorine is developed for the most part as gas, which will be led off and used
for any desired purpose, another smaller part being dissolved and diffused in the
osmose-compartment and in the anode-compartment where it is precipitated as chlorate
of potash or it may be used to make peroxide of lead or otherwise. By using the
reagents in excess to combine with chlorine the dissolved part of chlorine is increased,
whilst by passing a current of air or other suitable gas round the anode through the
solution or by using suction the gaseously developed part of chlorine is increased
and in this case the osmose-compartment and the anode-compartment may be
disused.
The caustic soda diffuses in the osmose-compartment as well as the cathode-
compartment and is there precipitated either by adding an acid forming a salt soluble
with difficulty or by adding a salt of such acid which yields its acid to the sodium.
The cheapest will be carbonic acid but its employment offers two inconveniences.
First, to saturate a solution with a gas requires either a long time or high pressure,
secondly the precipitating reagent cannot be added but in the proportion of the
diffusion of the substance to be precipitated, provided that reagent be not insoluble
like for example carbonate of lime to precipitate sulphuric acid. But it is very difficult
to add a gaseous soluble substance like carbonic acid in such a way, that its amount
accords exactly with that of the dialysed body.
All these inconveniences are obviated by the following process. Into the osmose-
compartment is put magnesia (hydrate, oxide or carbonate) and then only the carbonic
acid is introduced. The absorption of the carbonic acid then goes on very readily and

page_text: completely without pressure for the gas is absorbed by the magnesia in so far as the
caustic soda cannot combine with it quickly enough.
The process is preferably conducted long enough to prepare the badly soluble mixed
Carbonate of Sodium-Magnesium.
A surplus of magnesia does no harm.
The method just described can be used for many purposes especially for the manu-
facture of potash because of the bicarbonate of potash not being very insoluble at
ordinary temperatures. As it is clear, the latter process consists in adding a substance
which acts like a reservoir and transmitter. It stores up the surplus of gas not being
fit for immediate use and transmits it later to the substance to be saturated. Therefore
any other similar acting substance may replace the magnesia and any similar acted on
substance may replace the caustic soda, be the saturating gas carbonic acid or other
gas and time power and expensive apparatus are saved.
But there is another advantage in the process. The mixed alkaline carbonates of
magnesia are easily decomposed by caustic alkali by heat, or boiling or by passing
steam through them and in the latter cases by regulating the steam or water the
solution of carbonate may be obtained of any strength for example to obtain directly
soda crystals. The carbonic acid is easily recovered by the decomposition itself and
the magnesia is fit to be used over and over again.
To prevent rotable dialysing from the anode-compartment to the cathode-compartment
the walls between these two compartiments should be somewhat less permeable than
the walls separating the electrode-compartments from the osmose-compartments or
preferably the hereinafter described means are employed.
To work another salt such for example as sulphate of Potassium, I proceed as
before but into the osmose-compartment beside the anode compartment is put (for
instance) carbonate of lime, when gypsum will precipitate and carbonic acid will be
developed.
It will be clear now that the salient feature of the new process does not reside in
any particular form of apparatus but in the proper combination of osmose with
precipitation, electrolyses with precipitation or osmose, electrolysis and precipitation
processes, but notwithstanding that, some improvements in the apparatus inay be
employed which I have found very useful.
It is a long felt deficiency that the permeable walls necessary for asmose and for
certain kinds of electrolysis prove inconvenient. The resistance of diaphragms is not
always the suitable one, and their manufacture is difficult as is the case for instance
with large porous thin clay-plates. Then again the diaphragms become rapidly
deteriorated which is the case with parchment paper and further the materials suited
for the porous plates or vessels are very limited and that alone accounts for much of
the want of use of dialysis in the arts.
All these drawbacks I obviate by constructing these permeable walls in the following
manner.
Rods, sticks, pipes or the like of any diameter and any shape (for example, round,
elliptical, square, three cornered or like strips or ribbons) and of any material are put
together one above the other or one beside the other and are kept in place at the ends
by insertions in grooves in a stand, or frame or the like, so that they form a wall of
which the joints are close enough to prevent, if the wall be placed in a liquid
communication from side to side except by diffusion. Such walls have the further
advantage of easily allowing increase or decrease of permeability. The permeability
is augmented if many thin rods or the like are used or if the rods and the like are

page_text: applied not quite close together. The permeability is diminished if a few thick rods
or the like be used, if they be slightly pressed together or if there are applied (with or
without spaces between each wall) several such walls together or if the joints of each
wall be placed reversely to each other.
Two or more such walls may likewise be so arranged that the rods of each wall
cross those of the other wall or walls.
The rods or the like may have any shape as may also the walls formed by them.
For instance to build vessels with round walls each rod may be closed forming a ring,
which rings are then superposed or a rod may be wound in a spiral, each convolution
touching the adjacent ones and having the diameter of the vessel required or the
rods may be arranged in a circular series kept together by rings or a circular
In place of making the walls of rods, perforated plates can be used, which are
superposed with or supported behind each other, the openings in one not coinciding
with those in the adjacent ones.
frame.
The diffusion by such walls is brought about mainly through the medium of
capillary attraction between the surfaces arranged near together.
The layers of liquid formed by this capilliary action themselves constitute good
diaphragms and so liquids, if properly applied, may be used as diaphragms and the
construction of such liquid diaphragms" is very simple. Their effect is a very high
one and notwithstanding their good separating power they offer a small resistance
which is most important, because of its permitting a much greater useful effect for
electrolytic purposes.
It is the best to make the "liquid diaphragms" as thin as possible. It may be
very narrow if the liquid thereof is employed but for simple separation. It must
become larger if it is intended to carry a solid reagent or precipitates are formed
there.
To make such liquid diaphragms the vessel is divided by two walls made from any
material, provided it resists the action of the solutions. These two walls are put near
together. The two walls should not only be very porous but preferably they are even
perforated by small openings such as holes, slits or the like, for their only object is to
contain between them the liquid which constitutes the real diaphragm.
The liquid between these walls may be the same as the solution under operation, or
it may carry a reagent, combining with one or more of the products obtained by
electrolysing chloride of sodium for example to keep the diffusing chlorine back, it
may carry lime, or other suitable substance, or two such diaphragms may be used one
stopping chlorine, and the other caustic soda: By the slow diffusion of the surrounding
liquids the intermediate liquid between the walls gets deteriorated and it must therefore
be renewed either intermittingly or by continuously flowing through.
These "liquid" diaphragms allow likewise profitable use to be made of the osmatic
effect of the electric currents for example, in electrolysing caustic alkalies the alkalies
concentrate against the anode, therefore they may be precipitated there, or two liquid
diaphragms are placed one behind the other, when the caustic alkali is precipitated in
the one, and the diffusing chlorine is taken off in the other.
For the same purpose an intermediate compartment with permeable walls can be
used be the walls solid or liquid as in reality the intermediate compartment would be
but a large liquid diaphragın.
"
These liquid diaphragms prevent likewise the dialysing between the electrode-
compartment, namely the caustic soda (for example) formed diffuses first equally to
both sides, but being precipitated on the side of the osmose compartment it diffuses
then only there. The small quantity of chlorine diffusing into the "liquid diaphragm
is neutralised by the caustic alkali, and is afterwards run off and such small quantity
of caustic alkali must be replaced by means of renewed diffusion. By employing two
liquid diaphragms that quantity is further reduced.
To recapitulate the main essential feature of the invention is to precipitate
systematically by chemical means the soluble products which by their accumulation
would stop osmatic and electrolytic processes and to effect by such combined process

page_text: results, not so easily or not so completely to be got by the hitherto employed means.
The processes as hereinbefore shewn are combined, osmotico-precipitating electro-
lytico-precipitating and electrolytico-osmotico-precipitating.
The process not being dependent upon any special apparatus allows me to employ
or easily to adapt the usual apparatus and to simplify it by the introduction of a
chemical reagent acting like a reservoir, or a transmitter as hereinbefore described,
and by means of the walls of rods or the like and the "liquid" diaphragms each
alone or all combined the apparatus is simplified supervision is reduced and labour,
time, and power are economized.

page_text: Improvements in the Method of and Means for Separating Matters
in Solution by Osmose, Dialysis or Diffusion, or by Electrolysis,
or by a Combination of those Processes.
I JULIUS MARX of 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 :-
This Invention relates to the method of and means for separating matters in
solution by osmose (dialysis or diffusion) or by electrolysis or by a combination of
these processes.
In the said processes as hitherto conducted the soluble bodies sooner or later cause
a stoppage of the process by reason of the solubility of these soluble bodies and I
have devised means for making these processes continuous and complete by removing
the prime cause of the evil i.e. the said solubility and this I effect by precipitating the
soluble bodies after the reaction has commenced but before the reaction could be
stopped again by the increasing accumulation in the solution of these soluble bodies
and the effect of this new process is the greatest if the precipitation be done by
measure of the diffusion or production of these soluble bodies.
In the Specification of my application for Patent No. 6417 of 2nd May 1887 I have
described the influence of such soluble bodies in the electrolysis of alkaline and similar
salts and likewise a plan of obviating the defect by the simple and direct addition of
an acid forming a salt less soluble than the salt originally electrolysed.
My present invention relates to the employment of that process for the precipitation
of dialysed bodies and also to means for and the mode of application of those means
to processes by osmose and electrolysis for treating compounds yielding soluble
products under electrolytic action and my invention refers further to the combination
of both these processes.
وو
I use the terins * osmose ""dialysis" and "diffusion as having the same meaning
and to facilitate description I call that liquor or solution which becomes filled with the
substance to be dialysed that is which contains it in solution the "filling liquor" and
I call that liquor or solution which keeps the dialysed substances dissolved (or which
would keep the dialysed substances dissolved if I did not precipitate these substances)
the "solvent liquor."
I will explain firstly my invention as applied to osmose.
The separation of the different substances of a solution by osmose as hitherto
performed or proposed to be performed is a troublesome operation. To overcome the
hitherto existing difficulties I precipitate the bodies intended to be obtained by osmose
as far as possible as they enter into the "solvent liquor" so that the dialysed body is
kept from concentrating in the "solvent liquor" and if the substance to be dialysed be
readded in proportion as it leaves the "filling liquor" the latter cannot become less
concentrated thus :-
1. The difference between the "filling liquor" and the "solvent liquor” remains
practically the same throughout the process.

page_text: 2. By reason of that constant difference the process proceeds at the same rate
throughout.
3. The process may be interrupted as often and may be continued as long as
desired.
4. The substances to be dialysed are practically completely utilized.
It is very important for a successful working to see that the reagent serving to
precipitate does not act upon the substance to be precipitated beyond the amount
of its having diffused into the "solvent liquor" and if it be possible to add the
substance to be dialysed in a solid form it will prove more convenient than to add
it in solution.
If solid the substance to be dialysed may be contained in a bag, basket, perforated
trough or the like suspended in the "filling liquor" so as to keep it supplied with
the substance to be dialysed or such substance may be introduced mechanically the
amount introduced being regulated at will as required. The process becomes in
such case a very simple and easy one, there being nothing left to be done but to
supply into the "filling liquor" the substances to be dialysed and into the "solvent
liquor "the precipitating substance and to recover the precipitate. All these operations
can be done mechanically and thus labour can be minimised to the utmost.
a
Tho
The operation is not quite so conveniently performed if the substance to be dialysed
be employed in solution as in the case for example of sugar solutions, molasses
brines and the like. But these also may be freed from their contents more easily
by my invention than by the methods hitherto used. The solutions are dialysed either
intermittently by filling the apparatus dialysing completely at once emptying after
the operation and refilling or they can be dialysed continuously by combining
series of apparatus causing one or both solutions to flow through and concentrating
the "filling solution" again if need be after it leaves the last apparatus.
reconcentrated solution is then run back or mixed with the original solution.
Another advantage of my invention is that by judiciously choosing the precipitating
agent which will be evident to Chemists each component of a mixed compound may
be obtained separately. For this purposo it is but necessary to arrange a series of
dialytical compartments e.g. A vessel be divided into three compartments and filled
with water. If now pieces of sugar-beets be introduced into the first compartment its
their soluble compounds are diffusing into compartment No. 2 where lime is added thus
to precipitate Sulphuric and Phosphoric acid or parts of them when likewise some
organic impurities are precipitating. The sugar thus partly purified is diffusing into
compartment No. 3 where it is precipitated by baryta in the known manner.
saccharate of baryta thus obtained being already partly purified is easier to work
for manufacturing sugar.
The
By similar means mixed salts are treated to recover their different components
separately.
But the precipitation may be effected by an acid forming a salt less soluble than the
one originally operated upon as referred to in the electrolysing process described in
my before named Specification but likewise a compound may be used which
decomposes or combines with such substance by making it insoluble or soluble with
difficulty such as bicarbonate of magnesium with caustic soda or as baryta with
sugar or a compound may be used which combines with the substance to be pre-
cipitated by forming an insoluble or difficultly soluble mixed compound such as the
carbonate of sodium and magnesium.
Another way as hereinafter described is to form such compound from its component
in the solution itself.
By precipitating after one of these methods not only the osmotic process but also
the electrolysis of compounds whicb yield soluble products under electrolytic action
will be made continuous.
The process I prefer for electrolysing is one in which osmose is combined with
electrolysis when the electrolytic products may be led off continuously or the osmose
may be worked along with electrolysis assisted by my precipitating method and I
shall now give an example to show how this operation may be performed.

page_text: I have chosen as an example the decomposition of chloride of sodium because that
salt is very common and because it can serve to show all three phases of my inven-
tion at once, each alone and each in its connection with and influence upon the
others. From this a Chemist will readily understand the small alterations to be
made for working other products by my process which alterations mainly will consist
in the employment of another suitable precipitating reagent I do not confine myself to
chloride of sodium nor to the other sodium or potassium salts as any substance capable
of being dialysed or of being electrolysed (and yielding by electrolysis soluble
products) may be treated by my process by choosing the proper precipitating
reagent.
The process may be carried out in any suitable apparatus but I have provided some
improvements in means or apparatus for the purpose which will much facilitate or
perfect the process and which may be used alone or be combined with the apparatus
hitherto used as they may readily be adapted to them.
Having provided a suitable vessel it is divided by three permeable walls into four
compartments. The two middle compartments contain the electrodes and I call them
"Electrode-Compartments" the one being for the anode and the other for the cathode
and I call them respectively the "anode compartment" and the " cathode compart-
ment." The two end compartments are intended to receive the products of the
osmose and electrolysis and I call these compartments "Osmose Compartments."
I further calling the "osmose compartment" connected with the anode compartment
" anosmose compartment and the osmose compartment connected with the
cathode compartment the "cathosmose compartment."
the
"
The whole apparatus is now filled with solution of chloride of sodium and in either or
both of the electrode compartments is suspended a bag basket or perforated trough or
the like kept filled with chloride of sodium and then the electric current is passed through
the solution. Chlorine and caustic soda are developed & diffuse into the osmose com-
partments, where they are precipitated and then a further quantity diffuses in and as
long as the precipitation is kept up the osmose continues and as long as the osmose is
kept up the electrolysis goes on properly, and as long as the electrolysis is kept up the
dissolution of fresh quantities of salt continues. Therefore all that has to be done is,
to close the electric circuit, to supply the salt as it becomes dissolved, and to remove
the precipitate. But this very simple process may be still further simplified. The
supply of the salt is easily made by mechanical means, and may then be regulated to
keep up any convenient strength of the solution, likewise the adding of the precipitator
and the taking out of the precipitated substance may easily be done mechanically, so
that nearly no manual labour has to be done and supervision is reduced to the
utmost.
The strength of the solution is best kept somewhat below complete saturation
because such a solution has the best conductive power.
The whole apparatus being filled with the same solution of salt and the solution
being kept the same strength all through no salt can diffuse but only the other soluble
products, namely, chlorine and caustic soda.
The chlorine is developed for the most part as gas, which may be led off for
manufacturing bleaching powder, or chlorates, or organic chlorides, or it may be used
for bleaching purposes, or to be liquefied or in fact it may be employed for any desired
purpose. Another smaller part being dissolved diffuses in the anosmose compartment
where it may be precipitated as chlorate of potash or it may be used to make peroxide
of lead or otherwise, for example the solution may be made to serve for bleaching.
By using in excess reagents which combine with chlorine the dissolved part of
chlorine is increased at will whilst by passing a current of air or other suitable gas
round the anode through the solution or by using suction the quantity of chlorine
developed as gas is increased. If the chlorine is to be led off as gas, the anosmose
compartiment may be dipensed with.
The caustic soda diffuses into the cathosmose-compartment and tends at first to
diffuse into the anode compartment, but as the caustic soda diffused into the cathosmose-
compartment is precipitated continuously it preferably diffuses toward that side, as
B

page_text: there the solution is kept the poorest in caustic soda. Or the resistance of the
diaphragm between the two electrodes might be made somewhat greater than the
resistance of the diaphragm between the cathode-compartment and the cathosmose-
compartment.
To precipitate the caustic soda carbonic acid is the cheapest and the drawbacks
accompanying that operation may be greatly reduced by proceeding as follows:-Into
the cathosmose-compartment is put magnesia (hydrate, oxide, or carbonate) and then
only the carbonic acid is introduced. The absorption of the carbonic acid.then goes
on very readily and more completely than without magnesia for the gas is largely
absorbed by the magnesia in so far as the caustic soda cannot combine with it
quickly enough.
The process is preferably conducted long enough to produce the badly soluble mixed
carbonate of sodium-magnesium.
A surplus of magnesia does no harm.
The method just described can be used for many purposes especially for the
manufacture of potash. The bicarbonate of potash not being very insoluble at ordinary
temperatures the precipitation of caustic potash by carbonic acid is very incomplete
or very troublesome. As it is clear in employing magnesia the improvement resides
in adding a substance which acts like a reservoir and transmitter. As it stores up the
surplus of gas not fit for immediate use and thereafter transmits it to the substance to
be saturated. Therefore any other similar acting substance may replace the magnesia
for example hydrate of zinc and any substance similar acted on may replace the
caustic soda for example caustic potash be the saturating gas carbonic acid or other
gas for instance sulphurous acid gas and time, power, pressure and expensive apparatus
are saved.
But there is another advantage in the process. The mixed alkaline carbonates of
magnesia formed in the process are easily decomposed by caustic alkali or by heat, a
most suitable way is to pass superheated steam through or over them and then by
regulating the steam and water the solution of carbonate may be obtained of any
strength for example to obtain soda crystals directly. The carbonic acid is easily
recovered and by the decomposition itself the magnesia is obtained fit to be used over
and over again or by employing for example Carnallit for electrolysing magnesia may
be manufactured.
To prevent or reduce potable notable dialysing from the anode-compartment to the
cathode-compartment the walls between these two compartments should be somewhat
less permeable than the walls separating the electrode-compartments from the osmose-
compartments or preferably the hereinafter described means are employed.
To work for example a salt such as sulphate of potassium, I proceed as before but
into the osmose-compartment next to the anosmose anode-compartment I put (for
instance) carbonate of lime, when gypsum will precipitate, and carbonic acid will be
developed. The oxygen is led off from the anode-compartment and the carbonic acid
from the anosmose-compartment and thus both gases are obtained separately. The
carbonic acid may serve for saturating purposes, and the oxygen for use in lighting,
Instead of carbonate of lime, phosphate of lime may be employed, when an acid
phosphate will be obtained very suitable as manure, especially if it he mixed with
sulphate of potassium. Or the phosphate monocalcic may be prepared and by the
addition of the caustic potash formed by electrolysing sulphate of potassium a very
good fertilizer of a double phosphate of potassium and calcium is to be obtained.

page_text: Or a chloride (for example chloride of calcium) may be added when the sulphuric
acid becoming free will precipitate again as gypsum yielding hydrochloric acid suited
for lixiviating or extracting ores.
It will be clear now that the salient feature of the new process does not reside in
any particular form of apparatus but in the proper combination of osmose with
precipitation, electrolysis with precipitation or osmose-electrolysis with precipitation
processes, but notwithstanding that, some improvements in the apparatus inay be
employed which I have found very useful and which easily are adapted to the usual
apparatus.
It is a long felt deficiency that the permeable walls necessary for osmose and for
certain kinds of electrolysis prove inconvenient. The resistance of diaphragms is a
given but not always a suitable one, and their manufacture is difficult as is the case
for instance with large porous thin clay plates. Then again the diaphragms become
rapidly deteriorated which is the case with parchment paper and further the kind of
materials suited for the porous plates or vessels are very limited and that alone
accounts in a great measure for dialysis not having been more extensively used in
the arts.
All these drawbacks I obviate by constructing these permeable walls or partitions
in the following manner.
Rods, sticks, pipes or the like of any diameter and any shape (for example, round,
elliptical, square, three cornered or like strips or ribbons) and of any material capable
of resisting the action of the surrounding liquids are put together one above the other
or one beside the other and are kept in place at the ends by insertions in grooves, in a
stand, or frame, or the like, so that they form a wall of which the joints are close
enough to prevent, if the wall be placed in a liquid, communication from side to side
except by diffusion. Such walls have the further advantage of easily allowing increase
or decrease of permeability. The permeability is augmented if many thin rods or the
like are used or if the rods and the like are applied not quite close together. In
the latter case preferably strips or ribbons are employed. The permeability is
diminished if a few thick rods or the like be used, if they be slightly pressed
together or if there be applied (with or without spaces between each wall) several such
walls together, especially if the joints of each wall be placed so that they do not
coincide with each other.
Two or more such walls may likewise be so arranged that the lengths of their
component rods or the like cross each other or so that the rods or the like of one wall
cross those of the other wall or walls or one wall may have its joints in a horizontal
direction and the next one in a vertical or diagonal direction.
The rods or the like may have any shape as may also the walls formed by them.
For instance to build vessels with round walls each rod may be closed forming a ring,
which rings are then superposed or a rod or. a number of rods and the like may be
wound in a spiral, each convolution touching the adjacent ones and having the
diameter of the vessel required or the rods may be arranged in a circular series
kept together by rings or a circular frame. Square vessels or other shaped vessels
may be similarly constructed.
In place of making the walls of rods, perforated plates can be used, which are
superposed with or supported behind each other, the openings in one not coinciding
with those in the adjacent ones. But these plates I find less convenient. These
openings may be regulated by mechanical devices.
In employing such walls the diffusion is going on between the joints or openings of
the single parts and the dialytic action is modified and regulated by the capillary
attraction between the surfaces arranged near or close together.
The layers of liquid formed by this capillary action thus constitute the diaphragms
and so liquids if properly applied, may be used as diaphragms and the construction
of such liquid-diaphragms is very simple. Their effect is a very high one and
notwithstanding their good separating power they offer a small resistance which is
most important, because of its permitting a much greater useful effect for electrolytic
purposes.

page_text: Such liquid diaphragms are provided for instance by constructing the permeable
walls described out of broad strips or ribbons, which may leave somewhat open joints.
Another way to make liquid diaphragms is the following.
al
The vessel is divided by two walls made from any material, provided it will resist
the action of the solutions. These two walls are put near together but leaving
space between them. The two walls should not only be very porous but preferably
they are even perforated with very small openings such as round holes or slits and
the like or the permeable walls mentioned above are employed when the permeability
may be regulated to suit circumstances.
The only purpose of these two walls is to prevent the liquid between them from
, mixing too rapidly with the surrounding liquors, and these two walls are not to cause
such a real interruption as the usual porous diaphragms for, the liquid between them
substitutes the diaphragm.
The liquid between these walls may be the same as the solution under operation, or
it may carry a reagent, combining with one or more of the products obtained. by
By electrolysing; hydrate chloride of sodium for example to keep the diffusing
chlorine back; or it may carry lime, or other suitable substance, or two such
diaphragms may be used one stopping for example chlorine; and the other caustic
soda. By the slow diffusion of the surrounding liquids the intermediate liquid between
the walls gets deteriorated and it must therefore be renewed either intermittently or
by continuously flowing through of fresh liquid.
These liquid diaphragms allow likewise profitable use to be made of the osmotic effect
of the electric currents, for example in electrolysing caustic alkalies the alkalies
concentrate against the anode, therefore they may be precipitated there; or two
liquid diaphragms are placed one behind the other, when the caustic alkali is
precipitated in the one, and the diffusing chlorine is taken off in the other or the
chlorine and the caustic alkali are made to combine in such a liquid diaphragm
between the two electrodes. Then hypochlorite of sodium for example forms.
By regulating the flow of that intermediate liquid the strength of the solution is
regulated and thus it is easily adapted to suit different bleaching purposes. By these
means a strong or a very weak bleaching solution may be obtained and after bleaching
the solution may he re-employed either for electrolysis or only for the intermediate
liquid. Or if no need for bleaching exists, the chlorine or caustic soda may be
employed otherwise as described above. Or during electrolysis greater or smaller
parts of chlorine or caustic soda are employed at the same time and at will either for
bleaching or for manufacturing purposes. It is clear that chlorates can equally well
be obtained by a similar process.
For the same purpose an intermediate compartment with permeable walls can be
used be the walls solid or liquid as in reality the intermediate compartment would be
but a large liquid diaphragm.
These liquid diaphragms prevent likewise the dialysing between the electrode
compartments, namely the caustic soda (for example) formed diffuses first equally to
both sides, but being precipitated on the side of the osmose compartiment it diffuses
then only there. The small quantity of chlorine diffusing into the liquid diaphragm
is neutralised by the caustic alkali, and is afterwards run off and such small quantity
of caustic alkali must be replaced by means of renewed diffusion.
By employing two liquid diaphragms that quantity is further reduced.
The main essential feature of the invention is to precipitate systematically by
chemical means the soluble products which by their accumulation would stop esmatie
osmotic processes and electrolytic processes (where soluble electrolytic products result)
and to effect by such combined process results, not so easily or not so completely to
be obtained by the processes or means hitherto employed or proposed. The processes
as herein before shewn are combined, osmotico-precipitating, electrolytico-precipi-
tating, and electrolytico-osmotic-precipitating processes.

page_text: The process not being dependent upon any special apparatus allows me to employ
or easily to adapt the usual apparatus and to simplify it by the introduction of a
chemical reagent acting like a reservoir, or a transmitter as hereinbefore explained
and by means of the walls of rods or the like and the "liquid diaphragms" each
alone or all combined the apparatus is simplified, supervision is reduced and labour,
time, and power are economized.
It will be understood that the processes can be carried on either at a low or at an
elevated temperature. A partial evaporation or a partial or complete re-saturation
may be effected before, during or after the operations described, and heating or
cooling may be applied before, during or after the said operations.
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. In separating matters in solution by osmose (dialysis or diffusion) or by
electrolysis or by a combination of such processes precipitating the soluble bodies
produced or diffused before or at the commencement of the accumulation of such
soluble products in their solution to prevent the injurious reaction set up by such
accumulation substantially as and for the purpose herein before described.
2. In separating matters in solution by osmose (dialysis or diffusion) or by
electrolysis or by a combination of such processes precipitating the soluble bodies
produced or diffused before or at the commencement of the accumulation of such
soluble products in a system of osmose compartments to obtain separately two or
more of the constituents or components of a solution substantially as hereinbefore
described.
3. In separating matters in solution by osmose (dialysis or diffusion) or by
electrolysis or by a combination of such processes effecting a continuous automatic
operation by firstly the suspension (in a suitable receiver) or by the regulated addition
of the substance to bo treated into the liquor to be acted on by osmose (dialysis,
diffusion) or by electrolysis, and by secondly the suspension or by the regulated
addition of the precipitating substance or substances into the liquor containing the
products of the osmose (dialysis, diffusion), of the electrolysis or of the osmose-
electrolysis.
4. In separating matters in solution by osmose (dialysis or diffusion) or by
electrolysis or by a combination of such processes, the combining of osmose, (dialysis,
diffusion) and electrolysis so as to carry off by osmose (dialysis, diffusion) the
products of electrolysis substantially as and for the purpose herein before described.
5. In the combining of osinose (dialysis, diffusion) and electrolysis carrying off by
ostnose (dialysis or diffusion) the chlorine and the base formed by electrolysis into
the same osmose-compartment to obtain bleaching liquor or chlorates, substantially as
and for the purpose herein before described.
6. In or for apparatus for the purposes described and claimed the construction or
arrangement of permeable walls in the manner herein before described.
7. In or for apparatus for the purposes described and claimed an arrangement
providing "liquid diaphragms" or partitions substantially as hereinbefore described.
Dated this 17th day of December 1888.
J. H. JOHNSON & CO.,
Agents.