AN IMPROVED MODE OF AND APPARATUS FOR PRODUCING PAPER PULP OR HALF-STUFF FROM WOOD AND OTHER FIBROUS MATERIALS
Year: 1869

page_text: LETTERS PATENT to John Wyatt Reid, of No. 40, Great Western
Terrace, Bayswater, in the County of Middlesex, for. the Invention
of "AN IMPROVED MODE OF AND APPARATUS FOR PRODUCING PAPER PULP OR
HALF-STUFF FROM WOOD AND OTHER FIBROUS MATERIALS."
Sealed the 20th August 1869, and dated the 22nd February 1869.
PROVISIONAL SPECIFICATION left by the said John Wyatt Reid
at the Office of the Commissioners of Patents, with his Petition,
on the 22nd February 1869.
I, JOHN WYATT REID, of No. 40, Great Western Terrace, Bayswater,
in the County of Middlesex, do hereby declare the nature of the said
Invention for "AN IMPROVED MODE OF AND APPARATUS FOR PRODUCING
PAPER PULP OR HALF-STUFF FROM WOOD AND OTHER FIBROUS MATERIALS," to be
as follows:-
My Invention relates to a new method or process for producing paper
pulp or half-stuff from wood and other similar fibrous substances, and
also to apparatus employed in practicing the said process.

page_text: Hitherto the method of treating wood for this purpose has been to
'first cut the same into small pieces or chips by a suitable machine, and
then place it in a strong metallic vessel of suitable form capable of being
made steam-tight. A strong solution of caustic soda is then added and
heat applied. In a short time the wood will absorb nearly one-third of
its bulk of the liquor, thus lowering the surface of the liquor much
below that of the wood, which as the heat continues to be applied would
thus be immersed in steam instead of liquor, and so become charred
and unfit for bleaching, besides remaining hard and unacted upon by the
alkali.
My Invention consists chiefly in subjecting the wood or other
vegetable fibres to the action of heat and alkali, and at the same time
protecting them during the whole process by keeping them covered by
the liquor from the deleterious action of the steam necessarily generated
by the heat. This object is accomplished either by confining the wood
so as to prevent its floatation, and then adding the alkaline liquor in the
requisite excess to the original vessel, or by first filling the vessel with
the wood and providing a separate reservoir communicating with the
said vessel, which may be stationary or rotating, by means of a pipe or
otherwise, so that as fast as the liquor is absorbed by the wood, straw,
or other material it is replaced from the reservoir, which is also steam-
tight. In the absence of these facilities a force pump may be used to
preserve the level of the liquor and keep it always above that of the
wood. By these means the whole of the wood or other fibrous material
is equally acted upon, and the pulp or half-stuff produced is all of one
quality and capable of being bleached at a small cost, which has never
been the case hitherto.
The strength of the caustic alkali varies from six to fourteen degrees
of Twaddel's gauge, and the temperature from two hundred and fifty to
three hundred and eighty degrees Fahrenheit according to the quality of
the wood or other material.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Wyatt Reid in the Great Seal Patent Office
on the 21st August 1869..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
WYATT REID, of No. 40, Great Western Terrace, Bayswater, in the
County of Middlesex, send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of February, in the.
year of our Lord One thousand eight hundred and sixty-nine, in. the
Thirty-second year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said John Wyatt Reid, Her
special licence that I, the said John Wyatt Reid, my executors,
administrators, and assigus, or such others as. I, the said John Wyatt
Reid, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might
make,, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "AN IMPROVED MODE OF AND APPARATUS FOR PRODUCING PAPER
PULP OR HALF-STUFF FROM WOOD AND OTHER FIBROUS MATERIALS," upon the
condition (amongst others) that I, the said John Wyatt Reid, my.
executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately.
after the date of the said Letters Patent..
NOW KNOW YE, that I, the said John Wyatt Reid, do hereby.
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying Drawing forming a part of this Specification :-
My Invention relates to a new method or process for producing paper
pulp or half-stuff from wood and other similar fibrous substances, and
also to apparatus employed in practising the said process.

page_text: Hitherto the method of treating wood for this purpose has been to
first cut the same into small peices or chips by a suitable machine, and
then place it in a strong metallic vessel of suitable form capable of being
made steam-tight. A strong solution of caustic soda is then added and
heat applied. In a short time the wood will absorb nearly one-third of
its bulk of the liquor, thus lowering the surface of the liquor much
below that of the wood, which as the heat continues to be applied
would thus be immersed in steam instead of liquor, and so become charred
and unfit for bleaching, besides remaining hard and unacted upon by the
alkali.
My Invention consists chiefly in subjecting the wood or other
vegetable fibres to the action of heat and alkali, and at the same time
protecting them during the whole process by keeping them covered by
the liquor from the deleterious action of the steam necessarily generated
by the heat. This object is accomplished either by confining the wood
so as to prevent its floatation, and then adding the alkaline liquor in the
requisite excess to the original vessel, or by first filling the vessel with
wood and providing a separate reservoir communicating with the said
vessel (which may be stationary or rotating) by means of a pipe or
otherwise, so that as fast as the liquor is absorbed by the wood, straw, or
other material it is replaced from the reservoir, which is also steam-
tight. In the absence of these facilities a force pump may be used to
preserve the level of the liquor and keep it always above that of the
material. By these means the whole of the wood or other fibrous
material is equally acted upon, and the pulp or half-stuff produced is all
of one quality and capable of being bleached at a small cost, which has
never been the case hitherto.
The strength of the caustic alkali may vary from six to fourteen
degrees of Twaddell's gauge, and the temperature from two hundred and
fifty to three hundred and eighty degrees Fahrenheit according to the
quality of the wood or other material.
To enable others skilled in the art to practice my Invention I will
proceed to describe its operation by the aid of the accompanying
Drawing, which is a longitudinal section of one form of the apparatus.
I take spruce pine, poplar, willow, bass, or other suitable wood; I cut
such wood into small pieces or chips by means of any suitable machinery
or apparatus. The best results are obtained when the knots are removed,

page_text: and the chips do not exceed in thickness from one-eighth to three-
sixteenths of an inch, the length or breadth being immaterial within
certain limits. When I use cane or bamboo the joints need not be
removed, and if straw, esparto, or flax are employed they need not be
cut. These chips or other materials I put into a strong cylindrical
vessel or boiler A capable of resisting high pressures, and which may be
either stationary or rotary, vertical or horizontal, and which may be
heated either by the direct application of fire, or indirectly by any well-
known means, excepting that steam must not be blown into the boiler
among the stuff as has hitherto been the ordinary practice, this latter
method having the effect of reducing the strength of the liquor, and also
apparently of injuring the stuff. The body of the boiler is nearly filled
with chips, sufficient space only being left for their swelling; the man-
holes B, C, are then made tight, and liquid alkali (caustic preferred) is
run or pumped in by the pipe D. In the case of spruce or white pine
chips the hest results appear to be obtained when the density of the
liquor is about ten or twelve degrees of Twaddell's aërometer, and when
nine hundred to ten hundred pounds of soda ash containing 50 per cent.
of soda are used for each ton of air-dried wood. Bamboo, cane, esparto,
straw, and similar substances require much less, the quantity varying
with the nature of the material; thus 8 degrees Twaddell does very well.
for bamboo, and six or seven degrees for straw. It is always better to use
a little more alkali than is just sufficient to neutralize the silica and the
gums and resins of the material operated upon. The body of the vessel A
is substantially of the same arrangement heretofore employed for a like
purpose. The alteration necessary to adapt it to the purpose of my
Invention is the attachment of the part E, and the nature of the said
Invention will be best understood by describing what takes place in a
boiler used in the ordinary way without this alteration.
Let us suppose the boiler to be of the ordinary form, the attachment E
being removed, and the said boiler being nearly filled with chips, as
herein-before described, and being also supplied with liquor to the
height of the line x, x; heat being now applied, as the pressure
increases the wood becomes saturated, absorbing about one-third of the
liquor, the surface of which instead of being found at x, x, falls to y, y,
thus leaving exposed to the action of the steam all the chips or other
material unprotected by the liquor between the two lines x, x, and y, y ;

page_text: the result is that all the stuff thus exposed becomes hard and difficult
to bleach, being only partially acted upon by the liquor, while the
portion below the line y, y, being protected by the liquor remains of a
good colour, and comes out in a condition resembling cotton wool for
softness.
To obviate the above-described inequalities of production I attach to
the original boiler or body A the reservoir E. communicating with the
body A by means of the perforated diaphram F. This reservoir I fill up
with liquor to the dotted line 2, .. The boiler is now closed steam-tight
and heat is applied till the thermometer G indicates. from 350° to 375°
Fahrenheit (a few degrees more or less being immaterial so long as the
chips remain immersed in liquor. This heat I keep. up for one or two
hours according to the nature of the wood or other material. I then
cool it down to below 212d, draw off the spent liquor, and discharge the
contents from the boiler. When properly boiled the chips or other
material should come out perfectly soft without any hard portions, so as
to take the form of half-stuff when merely squeezed dry in the hand.
The rising of the chips above the surface of the liquid into the reservoir
is prevented by the diaphragm F. The surface of the liquor at the com-
mencement being at z, z, at the end does not fall below z', '; thus
during the whole operation the chips or other material are thoroughly
protected by an unbroken covering of liquor.
It is obvious that similar results may be obtained by other apparatus
than that represented in the Drawing, for instance, by means of a force
pump to preserve the surface of the liquor always above the chips, or a
plain vertical boiler being only partially filled with chips, their floating
up being prevented by a perforated cover or diaphragm, and the necessary
excess of liquor being added to provide for the absorption.
When spruce or white pine or bamboo chips are properly treated they
are reduced to such perfectly clean and even half-stuff that nearly
seventy-five per cent. of the original liquor applied may be drained from
it, and fifteen per cent. more or thereabout may be extracted by pressure.
The spent liquor should be evaporated and the alkali recovered in the
usual way.
Having thus fully described my said Invention, and shewn how the
same may be conveniently and advantageously carried into practice,
I claim, the mode of and means for treating wood or other suitable

page_text: material for the purpose of making paper pulp, substantially as herein
described.
In witness whereof, I, the said John Wyatt Reid, have hereunto
set my hand and seal, this Twentieth day of August, in the year
of our Lord One thousand eight hundred and sixty-nine.
JOHN WYATT REID. (L.S.)