IMPROVEMENTS IN THE MANUFACTURE OF PAPER PULP
Year: 1884

page_text: I, ALEXANDER MITSCHERLICH 6 Leopold Street Friburg, Grand Duchy of Baden,
German Empire, Professor of Chemistry and Doctor of Philosophy do hereby
declare the nature of my said invention for "IMPROVEMENTS IN THE MANUFACTURE
OF PAPER PULP" to be as follows:-
The cellulose obtained from fibrous parts of plants by treatment with
solutions of sulphites or by other chemical processes in such manner that the
cellulose fibres are little or not at all injured, differs, when separated from the
materials with which it is treated and from the imperfectly fluxed parts of
the plants, from cellulose which is attacked by the chemical operation to which it
is subjected (such as when treated with soda lye) namely:
1. In that its comparatively strong fibres do not pass readily through the pulp
strainer of known construction because a considerable felting easily occurs.
2. In that, when it is freed in the usual manner from water and rendered air
dry, it is dissolved with difficulty.
Consequently, although the methods heretofore employed for the purification and
drying of such cellulose may be used, they are accomplished with great and not
easily surmounted difficulties.
Firstly. The separated and when desired, washed material obtained by chemical
processes when treated with a considerable quantity of water contains in addition
to the substances soluble in water.
1. Suspended cellulose fibres, and ;—
2. Imperfectly fluxed particles of plants, such as bits of branches, also, when
calcium bisulphite or similar chemicals are used, particles of gypsum, sulphite of
lime, or other bodies that are insoluble or soluble with difficulty, are present. The
small suspended cellulose fibres have now to be separated by the purification from
the impurities set forth under the second head. It is therefore mainly a question
of separating impurities from the paper material that have been produced by the
chemical process and that have almost the same specific gravity as the cellulose
fibres and only differ from these in their greater volume. They consist as already
indicated of imperfectly fluxed particles of plants, that have withstood the chemical
actions to a greater degree on account of the nature of the wood.
In addition, those impurities that have been produced in the cellulose by the
nature of the chemicals used (such as granules of gypsum, sulphite of lime etc.)
have also to be removed. In order to attain the before mentioned end, the methods

page_text: and arrangements for the purification must be different from those required for
separating paper materials from sand etc. (sand trap) or for the separation of the
paper materials from water such for instance as is effected in the sorting of waste
materials in the manufacture of paper by "Schuricht's" apparatus. With the
latter arrangement, the paper materials superficially sorted are essentially only
filtered.
The following new method is of great service in the above mentioned mode of
purification. The material decomposed into its elementary fibres and mixed with
very large quantities of water, which must be more than 1500 times that of the
cellulose, is caused to flow slowly and horizontally through long comparatively
broad and deep boxes with very slight inclination and having at bottom partitions
of equal height, so that the impurities deposited on the bottom may not be carried
along by the current.
In the said partitions are advantageously placed closely fitting removeable boxes
or trays that are removed and emptied from time to time. The coarser suspended
particles, consisting of the before mentioned impurities of the mass fall down,
because they can descend through the water with comparatively little friction, and
they are deposited on the bottom respectively in the trays. A downward flow
such as occurs in "Schuricht's" apparatus, does not take place, and it is to be
particularly avoided as detrimental, and in particular no filtration, such as occurs
in "Schuricht's" apparatus must take place, as by this means the useful fibres are
separated with the impurities, and thus a purification is rendered impossible. The
movement of the liquid must, as before stated, be very slow in the new mode of
purification because if the flow were rather rapid, the impurities in question,
would on account of their great volume and comparatively low specific gravity not
become deposited at all or with great difficulty, and the purification would therefore
be very imperfect.
With other known methods of purification of paper materials a rapid flow is not
detrimental, as for instance, in the separation of sand when using sand trap, as
this becomes deposited even with a rapid flow, on account of its high specific
gravity.
With the above described method and apparatus a continuous and very exhaustive
purification of the material is effected.
When the material has passed through this purifying process it only contains
such impurities as may have retained therein on account of careless handling of
the apparatus, and such as exist in a very finely suspended state. In order to
insure perfectly against the first named impurities, the following arrangement is
employed.
In the purifying apparatus heretofore used for the separation of the coarser
particles (pulp-strainer) the principle has always been adopted of causing the fibre
mixed with not more than about 200 times the quantity of water to be forced with
violent motion accompanied by considerable noise through plates having slits.
This arrangement has proved to be very unsuited for easily felting fibres such as
sulphite cellulose because if the powers of production are to be somewhat satisfactory,
either the slits must be made so wide, that the pulp strainer such as heretofore
employed do not effect the required purification, or such a number of them
must be employed that the arrangement becomes very complicated and expensive.
In contra distinction to the above described method of forcing the fibres through
the slits, the present improvement consists in suspending the fibres in more than
1500 times the quantity of water so as to enable the same to flow with the water
through a large number of slits in comparatively large tin sieves.
The tin sieve is fixed in the bottom of a frame and offers, for the hourly
production of about 220 lbs of purified fibre, an area of openings of about
300 square inches, it is hung in a large receptacle having a discharge opening at
such a height that the tin sieve is always covered with liquid. The flow of the
liquid through the tin sieve only takes place vertically downwards and is determined
by the difference of the level of the liquid respectively above the tin sieve and in

page_text: the receptacle into which it flows. In passing through the tin sievo only a small
portion of fibres is deposited on or over the slits thereof.
In order to remove these a comparatively slow up and down motion is imparted
to the tin sieves. The two above described modes of purification assist each other
in that in both a very large quantity of water compared with the cellulose
is used,
By the described motion of the tin sieve the deposit of cellulose above the tin
sieve is avoided and it is forced to pass through the slits of the tin sieve. The
impurities which may have existed partly float upon the liquid and partly are
deposited upon the tin sieve.
By this means a complete and reliable purification of the cellulose is effected.
A violent movement such as is employed in the pulp strainer is not of any advantage
in the above described method but produces the following disadvantages.
1. It effects a rapid widening of the slits (considerably wearing out the metal).
2. It requires comparatively a great amount of power (great noise).
3. It requires thicker plates (and consequently increases the cost).
The tin sieve can also be constructed of different form, such as deep boxes or
vertical cylinders closed at bottom that are moved slowly up and down in the
outer receptacles and which can be changed for removing deposit thereon.
By the described arrangement the following results are obtained:
1. All particles floating upon the water remain in the water above the tin sieve
and can be readily removed.
2. Any remaining larger bundles of fibres and other coarse particles are
separated from the finished material by the tin sieve, which consequently affords
perfect security for the removal of all coarse impurities.
3. The liquid being allowed to flow through the tin sieve and this having only a
small amount of motion imparted to it, enables the slit sieves to be formed by simply
punching comparatively thin sheet metal, while with the present usual method
accurately worked thick plates are required.
4. The whole contrivance can be constructed at a comparatively small expense.
5. The operation is carried on without noise.
6. With the described purifying process all violent motion is carefully avoided
and therefore the cellulose fibre, which is easily destroyed, is preserved from injury.
This is an important point for the production of strong material and one that has
been lost sight of in the ordinary process; it is further of a very great importance
for certain special appliances of the same.
After the cellulose has been subjected to the above described purifying process, it
can only contain very minute non-fibrous impurities that have remained suspended
during the process. For removing these, as also the large body of water that has
been mixed with the fibre, the ordinary methods of removing the water cannot be
advantageously applied. The arrangement now to be described consisting mainly
of a centrifugal apparatus, is most suitable for this purpose inasmuch as with
comparatively moderate dimensions, it effects the removal of large quantities of
water together with any minute impurities that may be present.
It consists of a rotating shaft a having arms bb to which are fixed bars cc
forming the framing of a cylinder open at both ends, the sides of which are formed
of wire or hair screens having about 500 openings in one square inch. When using
hair screens, special frames ee are advantageous having transverse bars f for
supporting the frames. The large quantities of water and the said impurities pass
through the openings while the fibres are retained by the meshes. These, which
are comparatively large, and the use of the screens render any clearing out by
a water jet quite unneccessary.
This centrifugal apparatus is placed slightly inclined; into its upper opening
passes a pipe or channel by which the large quantities of liquid are introduced.
The apparatus is rotated so rapidly that the water with the said impurities is
violently thrown through the meshes but not so rapidly that the fibro adheres
J

page_text: always to its sides. The cellulose deposited upon the sieve surface rotates there-
with up to the moment that its weight overbalances the centrifugal force, whereupon
it falls down and passes in consequence of the sloped position to a lower part of
the cylinder. There it is again raised and again falls into a lower position, and so
on, until it passes out at the lower end of the cylinder thus sufficiently drained for
further working off.
The cylinder instead of being rotated with uniform velocity may be rotated
with variable velocity, the quick rotation effecting the removal of the water and
impurities, while the slower rotation causes the fibre to fall off.
It is of course essential for the effective action of the centrifugal apparatus, that
the cylinder shall not dip into the liquid.
The form of the apparatus may be variously modified, thus it may be made
conical but this does not offer any particular advantages.
The advantages of this continuously acting centrifugal apparatus are "as
follows:-
1, Removal of the impurities through the meshes of the screens.
2, Rapid removal of large bodies of water from the suspended fibre.
3, A perfectly continuous operation.
4, Small dimensions and cheapness of the apparatus combined with large powers
of production.
The large quantities of water employed in the process; which can be partly or
almost entirely used again, possesses, in certain modes of production of fibre,
particular advantages, consisting mainly in the easy removal of impurities that are
dissolved with difficulty.
For the purification of ground rags paper materials made of straw and alfa,
natron-cellulose, wood paste and similar materials the above described operation
may also be employed, with such corresponding modifications as will be readily.
understood.
Secondly. After the main removal of the water from the purified material, it is
subjected to known processes wherein by greater or less pressure, a very large
quantity of water is separated therefrom. With the products thus obtained, the
very great disadvantage arises with many materials, in particular with wood paste
and sulphite cellulose that they cannot be transported in a dry condition on account
of the difficulty with which they are dissolved, mostly requiring from 40 to 70
per cent of water to be left therein whereby the following disadvantages for
instances arise:-
1, The weight of the accompanying water so greatly increases the cost and
difficulty of transport, that the conveying thereof to distant places frequently has
to be abandoned.
2, In storing the undried materials it cannot be avoided that portions thereof
become dry and more or less insoluble. In this case the whole of the material will
have to be treated as though it were dry in order to render it soluble because other-
wise portions of dried material will not be disintegrated and will form knots in the
paper.
3, Furthermore the wet material is stored with greater difficulty than the dried
material and it also easily becomes rotten and consequently quite unserviceable.
These disadvantages have rendered it a very important question, with the daily
increasing production of wood paste and sulphito material, how to dry the material
by a continuous operation without interfering with its solubility. This problem
which has occupied many inventors latterly is solved by the following process.
The cause of the wood paste and similar substances becoming with difficulty
soluble does not lie, as is erroneously supposed, in the conversion of a portion of
the incrusting constituents into a glutinous substance when dried at too high
a temperature, which substance becomes cemented into a hard mass, the subsequent
dissolving of which in the rag engine is difficult (see Handbuch der Papier fabrication
of Hofmann, German Edition page 544 Berlin) but it lies in the following
circumstances.

page_text: The wood paste, etc, to be dried is at present subjected before drying to pressure
for the removal of the main body of water.
This pressure brings the smallest particlos into close proximity which is greatly
increased by the subsequent drying.
The small particles are thus caused to adhere so firmly together by the attraction
of adhesion that their solution in water is offected with difficulty.
With the sulphite material and similar materials that consist of comparatively
long strong fibres, an intimate. felting together thereof is effected by the said
pressure for the removal of the water, which is also greatly increased by the
subsequent drying. This felting together by reason of the greater brittleness of
these fibres remains with the subsequent addition of water and thus causes the
insoluble character of the material.
By the following process all paper materials can be prepared continuously in an
air dry, and at the same time easily soluble condition.
The material suspended in water is spread in a moderately thick layer, as in the
manufacture of paper upon a cloth or wire gauze through the perforations of which
the water passes, being if necessary drawn off by exhaust.
The material is still in a perfectly loose condition in which without being subjectod
to any pressure, the remainder of the moisture is removed by evaporation.
After such drying, the material may then be subjected to pressure without
detriment to its easy solubility because then the smallest particles have sufficient
elasticity to prevent a subsequent felting together or adhesion which is not the
case when subject to pressure before drying.
For carrying out this last part of the invention, known arrangements of apparatus
can be readily employed :-thus there may be used.
1) And endless sieve on to which the liquid containing the material in suspension
is made to flow and which may have known exhaust arrangements applied theroto.
2) A drying apparatus consisting of drying cylinders or other known arrange-
ments in order to remove the remaining water from these thin boards and
3) Pressing rollers which press the dried material together and render it easily
transportable.
It has been found that in carrying out the above process with sulphite materials
this becomes frequently discolored (grey and brownish). This occurs even when
water free from iron is used, and is due to the presence of small particles of iron
from the apparatus which become dissolved by the remaining small quantities of
acid in the liquid. It may be avoided either by covering the iron parts with wood,
canvas etc, or by the addition of an acid or of a soluble acid compound to the
water.
ABEL & IMRAY,
Agents for the Applicant,
28, Southampton Buildings,
London, W.C.

page_text: I, ALEXANDER MITSCHERLICH of 6 Leopold Street Friburg, Grand Duchy of
Baden German Empire, Professor of Chemistry and Doctor of Philosophy, do
hereby declare the nature of my invention for IMPROVEMENTS IN THE MANU-
FACTURE OF PAPER PULP" and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :—
.
My invention relates to those parts of the process for the manufacture of
cellulose fibre in general and paper pulp, especially in which this latter (prepared
beforehand either by treating the raw material with sulphite solutions or other
chemical substances, or by a mechanical process) is to be purified and the cellulose
fibres, which are in a fine distribution separated from the imperfectly fluxed
particles and the impurities and also dried and anhydrated in such a manner as to
give as result a pure and easily soluble material.
In the annexed drawings Fig. 1 shews a diagrammatic top view of the apparatus
which is used in the part of the process relating to the purification; fig. 2 a
diagrammatic side elevation of the same apparatus, partly in section.
Fig. 3 is part of the sieve used in this process shewn to a larger scale.
Fig. 4 a diagrammatic side elevation of the apparatus, which is used in the part
of the process relating to the complete drying and anhydrating of the material.
Fig. 5 is a diagrammatic top view of the last mentioned apparatus and Fig. 6, is
the centrifugal apparatus used in the purification process, shewn to a larger scale
In order to carry out the first part of my invention, namely the purification of the
paper pulp, I dilute material consisting of long fibres such as for instance sulphite
cellulose after having decomposed or disintegrated it into its elementary fibres
with an extremely large quantity of water; that is to say in a volume at least
1500 times greater than that of the cellulose. The liquid obtained in this way I
cause to flow slowly and horizontally, with a very low velocity through the
apparatus described hereafter and shewn in figs 1 to 3 of the annexed drawings.
The small and finely distributed particles, that is to say especially the pure
cellulose fibres will then be carried on with the current of the liquid, whilst all
coarser particles and those of the same specific gravity but of a greater volume,
that is to say the impurities fall down to the bottom of the apparatus.
The apparatus represented in a diagrammatic manner at figs. 1 and 2 consists of
very long and comparatively broad and deep receptacles or boxes or channels a a
with a very slight inclination These receptacles a have on their bottom
partitions bb of essentially equal height so that the impurities deposited on the
bottom may not be carried along by the current of the liquid.
In these partitions there may be placed advantageously closely fitting and
removeable boxes or trays which may be removed and emptied from time to time.
All the particles which are not very finely distributed and which consist of the
impurities of the mass, fall down because they pass through the water with but
little friction as compared with their mass and they are deposited on the bottom or
in the trays.
Behind the channel a there is placed a comparatively large vat c in which a
further deposition of the impurities will take place, as the velocity of the current

page_text: is here much slower. In this vat ca partition d reaches into the liquid to keep off
the impurities floating or swimming on the latter. From this vat o the liquid
flows to a smaller vat e from which it is raised by a lifting apparatus f of any
suitable construction (in the drawing an archimedian screw or creeper is shewn
by way of example) to a distributor g-of the liquid and from this to the second
apparatus which is to be used in place of the pulp strainer of ordinary construction.
In the last mentioned and well known apparatus the principle has always been
adopted of causing the fibres (diluted at the most with about 200 times the
quantity of water) to pass through plates having slits with violent motion and
accompanied with considerable noise. In order to obtain a satisfactory production
of material with long fibres, as for instance sulphite cellulose, these slits were made
so broad that hardly any purification took place, or else a great number of such
apparatus had to be employed in which way the arrangement proves very
complicated and expensive.
The new apparatus receives the liquid, as mentioned, in a very dilute state so as
to enable the fibres to flow with the water through a large number of slits in the
comparatively large tin sieves.
This apparatus consists, as it may be seen at figs. and 2 of a receptacle j j in
which a sieve i is suspended by a frame h. By means of rods or bars w the sieve i
with the frame h is put in a slow vertical alternate motion. The perforations or
Blits of this sieve which are shewn in fig 3 to a larger scale are chosen of such
dimensions as to offer an area of openings of about 300 square inches for an hourly
production of 220 lbs. of the long fibres, which are to be purified as for instance
sulphite cellulose or an area of 0.2 square metres for a production of 100 kilo-
grammes of the material mentioned.
The sieve may sometimes also be employed in another arrangement as shewn
in the drawing for example in the shape of deep boxes or vertically arranged
cylinders with closed bottoms which move slowly and vertical or horizontally
alternatively and may also be removeable to withdraw the deposited impurities.
The material for these sieves may be of very thin sheet metal in which the
slits are punched or stamped in a very rough manner. The liquid passes the
distributor and can if necessary be more diluted with water coming through
the pipe and then according to the very small difference between the levels from
the liquid above the sieve and the liquid contained in the receptacle j j, the liquid
flows with a very slow velocity in a vertical direction through the slits of the
sieve . By means of this diluted state of the liquid and the above mentioned
motion of the sieve the deposition of the pure fibres above the sieve is avoided
and the latter will be forced to flow with the water through the slits of the sieve
whilst the impurities remain partly floating or swimming on the liquid and partly
deposited on the sieve itself.
The receptacle j may sometimes also have a space which is separated from the
other part of the receptacle by means of a partition kk arranged in the receptacle j
and which does not reach the bottom of the latter. From this space the
impurities which may be deposited in the receptacle, can be easily withdrawn.
For a further cleaning of the receptacle jj, the openings m m are arranged, which
latter are closed during the ordinary working of the apparatus.
From the receptacle ; the liquid, which contains now almost only the cellulose
fibres in a finely distributed state passes through the opening or overflow n into
the channel o. This opening or overflow n is arranged in such a position and
manner that the sieve i is always covered by the liquid. In the channel o some
inclined transverse partitions x x are arranged for the deposition of the impurities
which the liquid may perhaps yet carry along with it.
The great quantity of water in which the cellulose fibres have been distributed
during the process mentioned is now removed from the purified cellulose by an
apparatus marked p in Figs 1 and 2 and represented on a larger scale in tig. 6.
This apparatus operates by centrifugal force and effects with comparatively

page_text: moderate dimensions the removal of large quantities of water together with any
minute impurities, that may be present.
This centrifugal apparatus consists of a rotating shaft a having arms b to which
are fixed bars c c forming the frame of a cylindrical or conical shaped drum open
at both ends, the sides of which are formed of wire or hair screens. When using
hair-screens special frames ee which have transverse bars f for supporting the
screens are advantageously employed. The openings of the latter are chosen so
large and of such a quantity that the water and also fine impurities which perhaps
may yet be in it, can pass through whilst the cellulose fibres are retained by the
meshes and remain on the inside of the screen.
This centrifugal apparatus is placed slightly inclined and its upper opening is in
connection with the above mentioned channel o by means of a pipe or channel,
through which all the great quantity of the liquid is introduced. The apparatus
is then rotated so rapidly that the water with the said impurities is violently
thrown through the meshes but yet not so rapidly that the fibres may adhere
on the inside of the screens. The cellulose thus deposited upon the inside
screen surface rotates therewith until by gradual accumulation its weight over-
balances the centrifugal force whereupon it falls down and passes in consequenco
of the inclined position of the apparatus to a lower part of the drum.
There it is again raised and again falls into a lower part and so on, until it
passes out of the drum in a state in which it is dry enough for further working.
For the effective action of this centrifugal apparatus it is of course essential that
the drum should be placed beyond the liquid and should not dip in it; and
this arrangement must especially be made for the outlet pipe or channel of the
dried cellulose.
The withdrawn water flows from the apparatus into the box q surrounding the
latter in its lower part and may from there either be discharged or guided througli
the channel into the channel s into which also passes the liquid for the receptacles
or boxes a. In this way a continuously circulating motion of the water is attained
and also a continuous working is secured by charging the material which is to be
purified into the channel t.
The apparatus may be rotated either with uniform velocity as described or also
with a variable one by which the quick rotation effects the removal of the water
and impurities while the slower motion causes the fibres to fall off.
The above mentioned dimensions are to be taken smaller if a material is to be
worked which has not such long fibres as the sulphite cellulose.
The material produced in this way is not yet dry and anhydrous enough to
transport it with advantage to a great distance. In the ordinary way the water
which this material still contains, is removed by subjecting it to known processes,
wherein by more or less pressure a very great quantity of water is separated
therefrom. The product thus obtained has only the disadvantage that it cannot be
transported in a very dry state on account of its being then only soluble with
great difficulty.
In order to avoid this disadvantage and to receive as result a product which is
easily soluble and air dry, it is necessary to subject the purified paper material to
a drying or anhydration process after which it may be subjected to pressure,
or not.
This drying or anhydration may be done in such may that the cellulose is now
once more diluted with water and then guided in a thin layer or coating (as is
done in the manufacture of paper or pasteboard) on an endless cloth or wire sieve
through which the water falls down and may if necessary also be sucked away.
The cellulose then remains in a loose state in which it loses its water 'by
evaporation, so that no pressure at all need occur. After this drying or
anhydrating a pressure of the product may, if necessary be employed, as now this
pressure does not diminish the solubility of the cellulose thus obtained. After
the described drying or anhydrating process the paper material is to be converted

page_text: into an easily soluble and a dry state. In order to carry out this process the
apparatus shewn diagrammatically in figs 4 and 5 of the annexed drawings can be
used. In this apparatus the cellulose is guided by an endless band B into a vat A
in which a stirring apparatus C is arranged and into which the necessary water
for the diluting of the cellulose is admitted by the pipe D. The mass or liquid is
now floating through a distributor E on to an endless sieve F, through which the
water runs away firstly spontaneously and lastly by the action of a suction
apparatus G placed under this sieve. In this way there remains on the sieve a
loose felt which is now guided from the sieve F over one or more drying
cylinders H or any other drying apparatus or oven. Here the felt assumes strength
and coherence enough to pass without any support over a drying cylinder J and
being now absolutely dry it is led from here to a pressure apparatus if the latter is
wanted. In carrying out the above mentioned process with sulphite material it
has been found that the latter becomes frequently discolored (gray and brownish).
This occurs even when water free from iron is used and is due to the presence of
small particles of iron from the apparatus which dissolve in the remaining small
quantities of acid in the liquid.
This may be avoided either by covering the iron parts of the apparatus, which
come in contact with the liquid, with wood, linen or such like materials, or by the
addition of free acid or of a soluble acid-compound to the water used in the process,
The latter must also to effected in the case when the use of water which contains
iron is not to be avoided.
Having now particularly described and ascertained the nature of my inven⚫
tion and in what manner the same is to be performed I declare that what
I claim is
1, The improved process for purifying and anhydrating cellulose fibres or the
paper pulp (prepared by the treatment with sulphite solutions or other chemical
substances or by a mechanical process consisting in guiding this material in a divided
state and greatly diluted with water with a very low velocity firstly in a hori-
zontal direction through long and wide receptacles or channels and afterwards in a
vertical direction through a large slit sieve which is arranged below the level of
the liquid and is agitated with a slow vertically alternating motion substantially
as and for the purpose set forth.
2, The combination of receptacles or channels a a of great extent which are
provided with partitions b b with a vat c and its partition d, for the motion of
the liquid in the horizontal direction, substantially as described.
3, The combination of a sieve i provided with slits a frame h, a receptacle j and
bars or rods w for moving the sieve for effecting the motion of the liquid in the
vertical direction after it has been raised by a lifting apparatus f and distributed
by a distributor g substantially as described.
4, The combination of the receptacle j with a a partition k k which does not
reach to the bottom of the receptacle to enable the impurities to be withdrawn
from the said receptacle substantially as described.
5, The improved process for drying or anhydrating paper pulp by means of a
continuously acting centrifugal apparatus in which the water is removed whilst
the paper pulp remaining on the inside of the screens, forming the surface of the
apparatus, is discharged therefrom in consequence of the inclined position of the
latter substantially as described.
6, The combination of an inclined axle a with arms b, frames c c and fand
wire-or-hair screens formning a cylindrical or conical shaped rotating drum, open at
both ends substantially as described and for the purpose set forth.
7, The improved method for completely drying and anhydrating paper pulp
consisting in guiding the material (after having been distributed in water and
freed from the latter in any known manner) without pressure and with or without
support over one or more drying cylinders or other drying apparatus or ovens in

page_text: such a manner, that here also it is not subjected to pressure, substantially as and
for the purpose set forth.
8, The combination of a vat A having a stirring apparatus C and the two
conduits B and D respectively for the pulp to be dried and for the water, with an
endless cloth or sieve F with or without a suction apparatus G and drying
cylinders Hand I or other drying apparatus or ovens substantially as described
and for the purpose set forth.
9; The covering of all iron parts of the apparatus used in this process which
come into contact with the liquid, with wood, linen and such like materials
substantially as described and for the purpose set forth.
10, The addition of acids or of soluble acid compounds to the water used in the
above described process for neutralizing the effect of iron should this be contained
in the water substantially as described.