AN IMPROVED METHOD OF TREATING WOOD FOR THE PRODUCTION OF PAPER PULP
Year: 1869

page_text: LETTERS PATENT to Thomas Cattell, of No. 188, Strand, in the
County of Middlesex, Doctor of Medicine, for the Invention of
"AN IMPROVED METHOD OF TREATING WOOD FOR THE PRODUCTION OF PAPER
PULP."
Sealed the 22nd February 1870, and dated the 30th August 1869.
PROVISIONAL SPECIFICATION left by the said Thomas Cattell at the
Office of the Commissioners of Patents, with his Petition, on the
30th August 1869.
I, THOMAS CATTELL, of No. 188, Strand, in the County of Middlesex,
3 Doctor of Medicine, do hereby declare the nature of the said Invention
for "AN IMPROVED METHOD OF TREATING WOOD FOR THE PRODUCTION OF PAPER
PULP," to be as follows:-
This Invention relates to the treatment of wood reduced to fibres,
filaments, or fine shavings by cutting, shredding, or otherwise, so as to
render the wood in its condition after such treatment suitable for the
production of pulp to be used in the manufacture of paper.

page_text: and especially by the mode described in the Specification of the Inven-
tion of Charles Farrar, of "Improvements in Machinery or Apparatus
for Reducing Wood to Fibres, Filaments, Shavings, or Fragments to be
employed in the Manufacture of Paper, Bonnets, Matches, and Scale-
boards, and for other Useful Purposes," and for which Letters Patent
bearing date the 8th day of December 1868, No. 3727, were granted to
the said Charles Farrar.
There are four processes to which recourse is to be had in effectuating
the treatment of the reduced wood.
By the first. The reduced wood is placed in a bath of water holding
in solution either phosphate of soda or bi-borate of soda, or silicate of
soda, or tungstate of soda, or carbonate of soda, or other alkali, or any
two or more of these alkalies in combination. If the wood under treat-
ment is resinous, then benzole or rectified naptha or petroleum spirit or
rectified turpentine or other volatile solvent having an action on resin
and not being soluble in water is to be added, or any one or more of these
solvents may be used in combination. And to facilitate the operation
the contents of the bath are to be kept in continuous agitation, and the
temperature thereof raised to a degree somewhat below that at which
the particular solvent or solvents employed would escape or be driven
off. This process may be further accelerated by mechanical compression.
By the second. On the termination of the first process the agitation
is to cease and the heat to be withdrawn from the bath, and its liquid
contents are to be drawn off into a suitable vessel for rectification and
future use. The ligneous material is to be subjected to a bath of water
and lime and sulphur, or caustic soda and sulphur, or other alkali or
alkaline earthy substance and sulphur. This process may be facilitated
by agitating and raising the temperature of the contents of the bath.
By the third. The ligneous material is to be submitted to the action
of sulphurous acid gas in suitable apparatus, or the sulphurous acid gas
may be condensed in water and so employed.
By the fourth. The ligneous material is to be washed in water and
immersed in a bath of the hypochlorite of soda, or of the hypochlorite
of lime, or other hypochlorite, or exposed to the direct action of chlorine,
and again washed in water, and again immersed in a bath containing
sulphite, bi, or hyposulphite of soda, or bi or hyposulphite of lime, or it
may be returned to the water from which it was previously taken, and
some aqueous solution of sulphurous acid gas added, or a stream of the

page_text: gas passed into the water. The ligneous material should be again
washed in water, when it will be ready for the beating engine, and form
pulp. The consecutiveness of the processes herein stated may be varied
gas passed into the water. The ligneous material should be again
washed in water, when it will be ready for the beating engine, and form
pulp. The consecutiveness of the processes herein stated may be varied
without affecting the result of the treatment or method herein set forth.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Cattell in the Great Seal Patent Office on
the 28th February 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
CATTELL, Doctor of Medicine, 188, Strand, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of August, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Thomas Cattell, Her special licence that
I, the said Thomas Cattell, my executors, administrators, and assigns,
or such others as I, the said Thomas Cattell, my executors, adminis-
trators, and assigns, should at any time agree with, and no others,
from time to time and at all times. thereafter 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 METHOD OF
TREATING WOOD FOR THE PRODUCTION OF PAPER PULP," upon the condition
(amongst others) that I, the said Thomas Cattell, 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 Thomas Cattell, 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:-
This Invention consists in the treatment and preparation of a fibrous
material from wood for the manufacture of paper pulp in the following

page_text: manner: The wood is taken either in the form of fine shavings, shreds,
filaments, in the state of sawdust, or in any other disintegrated form,
but I prefer to use the wood in the form of very fine shavings or
filaments, which have been well washed in cold water; I then place it
in a bath consisting of a solution of borate or bi-borate of soda or of
potash, or ammonia and phosphate of soda, or of potash or of ammonia
in the proportions of 3 lb. of the borate or bi-borate and 1 lb. of the
phosphate, together with 1 quart by measure of benzole, petroleum
spirit, coal tar, naphtha, bi-sulphide of carbon, rectified turpentine, or
other volatile solvent having an action on resin or resinous matters and
not being soluble in water, to every hundredweight of the raw material
to be operated upon. The bath is then heated by steam or fire under-
neath, or in any other convenient manner until it boils, and it is kept
at that temperature for about six hours with continuous agitation, until
on removing a small portion of the material from the bath and applying
to it a bleaching agent, such as the ordinary chloride of lime or chlorine
water, it is found capable of being readily bleached; this I call my first
process. The wood thus so far treated is then removed from the bath,
or the liquor is drawn from it, and the material left in the bath, and in
preference is washed thoroughly with either hot or cold water, and
boiled with continuous agitation for about four hours in a bath con-
sisting of either of the earthy or of the alkaline sulphides, preferring,.
on the ground of economy, the sulphide of lime or the sulphide of soda,
in the following proportions, namely, for every hundredweight of woody
fibre about 7 lbs. by weight of quicklime and 7 lbs. by weight of flowers
of sulphur, or about 6 lbs. of caustic soda and 5 lbs. of sulphur, or about
10 lbs. of soda ash and 5 lbs. of sulphur, all by weight. The sulphide of
lime is prepared by slaking the lime, and then intimately mixing the
flowers of sulphur with it, the requisite quantity of water being then
added, and the whole boiled for about an hour; any insoluble matter is
allowed to subside, the clear liquid alone being used. The sulphide of
soda is prepared by mixing either the caustic or the carbonate of soda,
or the soda ash and the sulphur together, and fusing them at a gentle
heat with stirring, and a solution is made by boiling either of those
products with water. After treating the material as above in the
sulphide bath the liquor is drawn off, and the material is drained.
without exposure to the air, and subjected to the action of sulphurous
acid, either in solution or by passing the gas itself into the bath, or
exposing it in a chamber to the action of sulphurous acid gas obtained

page_text: by the burning of sulphur, until the alkaline earths or alkalies are con-
verted into hyposulphites, when the material is thoroughly washed,
either by means of hot or cold water, and is converted into pulp in the
ordinary way; this I call my second process, which constitutes the
5 second and third processes described in my Provisional Specification.
For the purpose of producing paper pulp for the manufacture of paper
it is possible that by increasing the relative strength of the baths of the
sulphides, and likewise the duration of their application, to dispense
altogether with the process which I call my first process, but the result
is the production of a pulp of a quality very much inferior to what is
produced when the first process is also applied; it is also possible that
by increasing the chemical substances of which the baths in what I call
my first process are composed, and also by increasing the duration of the
boiling in that first process, to dispense altogether with the second,
process, but again in this case the result is the production of a pulp
equally defective in some of the qualities essential to the production of
a pulp capable of producing paper of really what I consider a high
quality.
Although in my first process I have named the borate or bi-borate
of soda or of potash, or of ammonia, and the phosphate of soda, or
of potash, or of ammonia, as the salts which I prefer to employ,
and also have given the proportions of these salts which I prefer to
employ in making my baths, yet these salts may be used in any pro-
portions with more or less effect, or one or either of. these salts may
be employed, or a solution of tungstate or silicate, or aluminate or
carbonate, or a mixture of one or more of these salts of the alkalies, or
other sálts of the alkalies with analogous chemical reactions may be
employed in making the bath, although I prefer to use the bi-borate of
soda, and also I prefer to use them in the proportions which I have.
given. In woods in which there is an entire absence of resinous
matters the baths of the salts of the alkalies may be made without
the addition of the volatile hydrocarbon or other resinous solvent.
The quantity of water in making the baths will vary in some respects
with the materials which may be under operation, but in all cases
the quantity of water should be such as to fairly cover and keep
the materials submerged during their treatinent, and again, the vessels
employed in making the baths may be either open or closed, but the
latter is preferred.

page_text: Although by the foregoing process or processes I have produced from
wood a material capable of producing truly good paper, still the material
or pulp may be further improved by what in my Provisional Specification
I call my fourth process, and which I have found of great value when
applied to paper pulp made especially from wood, and which may be
described as follows, namely, in submitting the material after the first
and second, or after the first or second process, or after the application
of either of these processes to a clear solution of a hypochlorite, or of
chlorine, applied in preference while the material is in the beating or
pulping engine, then washing the material in water, and further sub-
mitting it to a solution of a sulphide, or bi-sulphite, or a hyposulphite of
the alkalies, or of the alkaline earths, and these processes when necessary
are extended or repeated. In preference, and on the ground of economy,
using the solutions produced under the head of what I call my second
process, and finally thoroughly washing with hot or cold water, no
chlorine or chlorine compound being used after the application of the
sulphite, bi-sulphite, or hyposulphite.
In witness whereof, I, the said Thomas Cattell, have hereunto set
my hand and seal, this Twenty-eighth day of February, in the
year of our Lord One thousand eight hundred and seventy.
THOMAS CATTELL. (L.s.)