IMPROVEMENTS IN BLEACHING TEXTILE MATERIALS OR FIBRES, MORE ESPECIALLY WOOD PULP, FOR THE MANUFACTURE OF PAPER AND PASTEBOARD
Year: 1867

page_text: LETTERS PATENT to Alexander Clark, of Rathbone Place, in the County
of Middlesex, Executor of William Clark, late, of 58, Chancery Lane, in
the County of Middlesex, Engineer and Patent Agent (deceased), for
the Invention of "IMPROVEMENTS IN BLEACHING TEXTILE MATERIALS OR
FIBRES, MORE ESPECIALLY WOOD PULP, FOR THE MANUFACTURE OF PAPER AND
PASTEBOARD." A .communication from abroad by Jean Bernard Biron,
Merchant, of 29, Boulevart St. Martin, Paris.
PROVISIONAL SPECIFICATION left by the said William Clark at the
Office of the Commissioners of Patents, with his Petition, on the
11th May 1867.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer and Patent Agent, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN BLEACHING TEXTILE MATERIALS OR FIBRES, MORE
ESPECIALLY WOOD PULP, FOR THE MANUFACTURE OF PAPER AND PASTEBOARD,"
to be as follows:-
This Invention relates to a new mode of bleaching all kinds of textile
materials or fibres, and especially wood pulp, for the manufacture of paper and
pasteboard. Owing to the increasing demand for paper, and the limited supply
of rigs, various woods of a fibrous nature resembling flax, hemp, and cotton
have been employed for the production of paper and pasteboard.. According
-

page_text: to the improved mode of bleaching, of this Invention, both the strength and
suppleness of the wood pulp are preserved, of which essential properties it is
deprived by the baths of alkali, acid, aud chlorine of considerable strength in
which such pulps are prepared at the present time, to the deterioration of the
All white.
pulp, and although increasing its price above that of the best rags.
woods of a soft fibrous nature may be converted into pulp, some of which
woods grow in the vicinity of streams, and others, such as firs and pines, on
barren soils common to most places. One of the chief disadvantages of the
present modes of treatment consists in the greater or less degree of heat
employed for the disaggregation of the woody fibres which stain the pulp and
render the bleaching more difficult.
The following is the mode of treatment I employ for producing pulps
suitable for the manufacture. of paper and pasteboard:-The wood after being
split up is deprived of the bark, the knots, and heart, and then cut up
diagonally into pieces of about three inchies.square; it is then subjected to the
action of vertical stones or edge runners turning in an enclosed-space for, con-
taining the material; these stones by tlie aid, of water and quicklime in the
proportion of from -15 to 18 per cent.. of the wood treated effect the disaggre-
gation, and roughly separate the filaments. The wood after being cut up as
above described -should be immersed for about a month in water saturated
with lime before being acted on by the stones, as above mentioned,. whereby
the disaggregation of the fibres is greatly facilitated. The wood should
remain in the liquid until it acquires suflicient weight to sink to the bottom,
being stirred and turned from time to time.
The preliminary preparation of the wood and its subdivision by the edge
runners is effected at but small cost and in a short space of time as compared
to the treatment of rags. The wood being thus crushed is placed in heaps on
an inclined surface to facilitate draining off the lime water it contains, and
.after being macerated for several days in this manner it is placed in a washing
and subdividing cylinder, from, whence, it emerges bleached, or it may be
afterwards subjected to: the following improved mode of bleaching, which is
comprised in one simple operation:-1st, I immerse the partially, bleached
'pulp in a vat or cylindrical receiver containing water. charged with. a poly
sulphurous alkali. After numerous experiments made I prefer to use the
penta-sulphuret of potassium or of lime, the-latter-especially being obtainable
lat a very low price, and this in the great majority of cases where I employ
this simple mode of bleaching without the aid of chlorine:, 2ndly, after
agitating the mass for a few minutes until the pulp is well impregnated with
the solution of sulphuret, I pour into the receiver a solution of sulphuric

page_text: alum (acid sulphate of alumina) or of sulphuric or muriatic acids, in the pro-
portion of two parts of water to one of acid: Under. the influence of this?
mixture the solution of sulphuret immediately decomposes the acid, either
free or combined, eliminates the sulphur, and forms a salt from its alkaline
base, while the sulphur set at liberty owing to its greater affinity in a nascent
state combines with the hydrogen of the coloring matter of the wood. and
forms sulphuretted hydrogen, the presence of which may be readily ascertained
by its peculiar odour. Although I have observed that the hydrogen serving
to saturate the nascent sulphur is obtained from the coloring matter of, the
wood, it should not be forgotten that this decomposition is not obtained by,
pouring au acid into a solution of alkaline sulphuret, as in the present
instance the source of the hydrogen must necessarily be attributed to the
coloring matter of the wood, otherwise the bleaching of the wood pulp by the
reaction between the alkaline sulphuret in solution and the acid, either free
or combined with alumina, could not be explained. It is not less incontestable
that the wood pulp thus treated is instantly bleached, and that when combined,
with rag pulp it is suitable for the manufacture of many kinds of paper
er which
have hitherto only been produced from rags. The proportions of the two,
agents employed for producing the reaction and forming the combination used
in this improved bleaching process consisting of sulphuret and alum or acid
depends, 1st, on the greater or less amount of color, in the wood pulp, produced
by the edge runners and the subdividing cylinders; 2ndly, on the degree to
which the pulp is to be bleached. The proportion of dry sulphuret varies
between 1 and 5 per cent., while as regards the acid, although its chemical
equivalent to the proportion of sulphuret would be sufficient, it may be further
increased in order that the bleaching may be effected as quickly and com-
pletely as possible.
of
The proportions I generally find most suitable are as follows:-To one part in
weight of sulphuret five parts of crystallized alum, or five parts of muriatic
acid at 22 degrees, or three parts of sulphuric acid at 60. degrees. By treating.
the wood pulp with four per cent. of penta-sulphuret and 20. per cent. of
alum, or 20 per cent. of muriatic acid, or 12 per cent. of sulphuric acid, a
pulp may be readily obtained which if mixed with 40 or 50 per cent. of rags
and linen with the usual accessories produces a paper of sufficient whiteness
and good quality for newspapers and periodicals. The decolorizing action pro-
duced by the decomposition of the sulphuret in the wood pulp will have the
same effect on other textile materials suited to the manufacture of paper, by
treating them first with the above-mentioned agents and then subjecting them
to the action of chlorine baths they may be made to possess superior white-

page_text: ness than when chlorine alone is used in the same proportions. This is also
the case with wood pulp if the increased cost of bleaching were not an obstacle
to the employment of chlorine. .
SPECIFICATION filed in pursuance of the conditions of the Letters Patent,
and of an Order of the Lord Chancellor, by the said Alexander Clark
_ in the Great Seal Patent Office on the 13th December 1867. ·
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
CLARK, of Rathbone Place, in the County of Middlesex, Executor of William
Clark, late of 53, Chancery Lane, also in the County of Middlesex, who
departed this life on the 26th September 1867, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day, of May, in the year of our Lord
One thousand eight hundred and sixty-seven, in the, thirtieth year of. Her
reign, did, for Herself, Her heirs and successors, give and grant unto him,
the said William Clark, Her special licence that he, the said William Clark,
his executors, administrators, and assigns, or such others as he, the said
William Clark, his executors, administrators, 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 "IMPROVEMENTS IN BLEACH-
ING TEXTILE MATERIALS OR FIBRES, MORE ESPECIALLY WOOD PULP, FOR THE MANU-
FACTURE OF PAPER AND PASTEBOARD," a communication to him from abroad by Jean
Bernard Biron, Merchant, of 29, Boulevart St. Martin, Paris, upon the condition
(amongst others) that he, the said William Clark, his executors or administrators,
by an instrument in writing under his, 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 Alexander Clark, as, such Executor
aforesaid, do hereby declare the nature of the said Invention, and in what
manner the same is to be performed, to be particularly described and
ascertained in and by the following statement (that is to say) :-
This Invention relates to improvements in bleaching textile materials or
fibres, more especially wood pulp, for the manufacture of paper and pasteboard.

page_text: Owing to the increasing demand for paper, and the limited supply of rags,
various kinds of woods of a fibrous nature resembling flax, hemp, and cotton
bave been employed for the production of paper and pasteboard. According
to the improved mode of bleaching, of this Invention, both the strength and
suppleness of the wood pulp are preserved, of which essential qualities it is
deprived by the baths of alkali, acid, and chlorine of considerable strength in
which such pulps are prepared at the, present time to the deterioration of the
pulp, although increasing its price, above that of the best rags. All white
woods of a soft fibrous nature may be converted into pulp, some of which
woods grow in the vicinity of streams, and others, such as firs and pines, on
barren soils common to most places. One of the chief disadvantages of the
present. modes of treatment consists in the greater or less degree of heat
employed for the disagregation of the woody fibres which would stain the pulp
and render the bleaching more difficult.
...
The following is the mode of treatment I employ for producing pulps
suitable for the manufacture of paper and pasteboard:-The wood after being.
split up is deprived of the bark, the knots, and heart, and is then cut up
diagonally into pieces of about three inches square; it is then subjected to the
action of a vertical stone or edge runner turning in an enclosed space for con*
taining the materials; this stone by the aid of water and quicklime in the
proportion of, from 15 to 18 per cent. of the wood treated effects the disagre-
gation and roughly separates the filaments. The wood after being cut up as
above described should be immersed for about a month in water saturated
with lime before being acted on by the stones, as above mentioned, whereby.
the disagregation of the fibres is greatly facilitated. The wood should remain
in the liquid until it acquires sufficient weight to sink to the bottom, being
stirred and turned from time to time.
The preliminary preparation of the wood and its disagregation by the edge.
runners is effected at but small cost and in a short space of time as compared
to that required for the treatment of rags. The wood being thus crushed is
placed in heaps on an inclined surface to facilitate draining off the lime water
it contains, and after being macerated for several days in this manner it is
placed in a washing and subdividing cylinder, from whence it emerges
bleached, or it may be afterwards subjected to the following improved mode
of bleaching, which is comprised in one simple operation-1st, I immerse the
partially bleached pulp in a vat or cylindrical receiver containing water charged
with a polysulphurous alkali. After numerous experiments made I prefer
to use the penta-sulphuret of potassium or of lime, the latter being especially
obtainable at a very low price, and this in the great majority of cases when I

page_text: employ this simple mode of bleaching without the aid of chlorine. 2ndly, after
agitating the mass for a few minutes until the pulp is well impregnated with
the solution of sulphuret, I pour into the receiver a solution of sulphuric alum
(acid sulphate of alumina) or of 'sulphuric or muriatic acids in the proportion
of two parts of water to one of acid. Under the influence of this mixture
the solution of sulphuret immediately decomposes the acid; either free or
combined, eliminates the sulphur, and forms a salt from its alkaline base;
while the sulphur set at liberty owing to its greater affinity 'in a nascent
state combines with the hydrogen of the coloring matter of the wood and
forms sulphuretted hydrogen, the presence of which may be readily ascertained
by its peculiar odour. Although I have observed that the hydrogen serving
to saturate the nascent sulphur is obtained from the coloring matter of the
wood, it should not be forgotten that this decomposition is 'not obtained by
pouring an acid into a solution of alkaline sulphuret, as in the present
instance the source of the hydrogen must necessarily be attributed to the
coloring matter of the wood, otherwise the bleaching of the wood pulp by the
reaction between the alkaline sulphuret in solution and the acid, either free or
combined with alumina, could not be explained. It is no less incontestable
that the wood pulp thus treated is instantly, bleached; and that when combined
with rags it is suitable for the manufacture of many kinds of paper which
have hitherto only been produced from rags. The proportions of the two
agents employed for producing the reaction and forming the combination used
in this improved bleaching process consisting of sulphuret and alum or acid
depends, 1st, on the greater or less amount of color in the wood pulp produced
by the edge runners' and the subdividing cylinders; 2ndly, on the degree to
which the pulp is to be bleached. The proportion of dry sulphuret varies
between 1 and 5 per cent., while as regards the acid, although its chemical
equivalent to the proportion of sulphuret would be sufficient, it may be further
increased in order that the bleaching may be effected as quickly and com-
pletely as possible.
The proportions I generally find most suitable are as follows:-One part in
weight of sulphuret to five parts of crystallized alum, or five parts of muriatic
acid at 22 degrees, or three parts of sulphuric acid at 60 degrees. By treating
the wood pulp with four per cent. of penta-sulphuret and 20 per cent, of alum,
or 20 per cent. of muriatic acid, or 12 per cent. of sulphuric acid, a pulp may
be readily obtained, which if mixed with 40 or 50 per cent. of rags and linen.
with the usual accessories produces a paper of sufficient whiteness and good
quality for newspapers or periodicals. The decolorizing action produced by
the decomposition of the sulphuret in the wood pulp will have the same effect'

page_text: on other textile materials suited to the manufacture of paper, by treating
them first with the above-mentioned agents and then subjecting them to the
action of chlorine baths they may be made to possess superior whiteness than
when chlorine alone is used in the same proportions. This is also the case
with wood pulp if the increased cost of bleaching were not an obstacle to the
employment of chlorine.
An important point to be considered is that in all paper mills worked by
water power the surplus force obtainable during one-half of the year may be
utilized for preparing a supply of wood pulp, which may be immediately
bleached in the cylinders by means of the sulphuret and alum, and placed in
reserve without being previously washed, where it may remain preserved from
deterioration by the action of the sulphate of alumina for an indefinite period.
Hence it is simply necessary to wash the required quantity of pulp from time
to time in suitable cylinders which require but a small amount of power, and
then to mix it with the rags in the desired proportions for subsequent
treatment. In this manner any surplus power available in winter time in
these manufactories may be utilized, and so prevent a cessation of work during
the heat of summer when the water power falls off considerably.
I reserve the right of using the improved mode of bleaching herein-before
described not only as applied to wood pulp but also for bleaching all textile
and fibrous matters suitable for the manufacture of paper.
This improved bleaching or decoloring process for the treatment of wood.
pulp, and other substances utilizable in the manufacture of paper and paste-
board, may
also be used for the treatment of all analogous fibrous substances
applicable for other purposes.
Having described the nature of this Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is, the employment of alkaline
sulpburets as bleaching or decoloring agents in the manner and for the purposes
herein-before described.
In witness whereof, I, the said Alexander Clark, as such Executor, have
hereunto set my hand and seal, this Twelfth day of December, in
the year of our Lord One thousand eight hundred and sixty-seven.
ALEX. CLARK. (L.S.)