AN IMPROVED PROCESS AND APPARATUS FOR MAKING PAPER PULP FROM WOOD AND OTHER VEGETABLE FIBRES
Year: 1871

page_text: LETTERS PATENT to Charles Wedderburn Granville, late of Mansfield
Chambers, St. Ann's Square, Manchester, but now of Arundel
Street, Strand, in the County of Middlesex, Merchant, for the In-
vention of "AN IMPROVED PROCESS AND APPARATUS FOR MAKING PAPER
PULP FROM WOOD AND OTHER VEGETABLE FIBRES."
Sealed the 28th November 1871, and dated the 4th October 1871.
PROVISIONAL SPECIFICATION left by the said Charles Wedderburn
Granville at the Office of the Commissioners of Patents, with his
Petition, on the 4th October 1871.
I, CHARLES WEDDERBURN GRANVILLE, late of Mansfield Chambers,
St. Ann's Square, Manchester, but now of Arundel Street, Strand, in
the County of Middlesex, Merchant, do hereby declare the nature of
the said Invention for "AN IMPROVED PROCESS AND APPARATUS FOR MAKING
PAPER PULP FROM WOOD AND OTHER VEGETABLE FIBRES," to be as follows:-
My said Invention although applicable to the treatment of vegetable
fibres generally for the production of paper pulp or half stuff therefrom

page_text: is more especially designed to afford the moans whereby paper of a
superior quality may be economically manufactured from wood, and I
have therefore in the following description more particularly referred to
wood as the material treated by my process.
In preparing wood for conversion into pulp for the manufacture of
paper, the resin, turpentine, and other matters should be first sepa-
rated from the fibres, and for this purpose I proceed as follows:-I first
strip the bark from the wood and then reduce the latter to small shreds
or filaments by means of any suitable machine or apparatus. I then
place these wood shreds or filaments in water at a temperature preferably
of one hundred degrees Fahrenheit, and soak or ret them therein for a
period of about six weeks, this period being increased or diminished
according to the thickness of the shreds or filaments or the nature of
the wood. By this continued soaking the gummy matters in the wood
are dissolved, and the fibres are separated. The water should be changed
at the end of the third week. When the fibres have been sufficiently
soaked I pass them between heavy rollers to press or squeeze from them
tlie greater part of the water absorbed during the above process. The
fibres are then removed to my improved apparatus for bleaching them
and destroying the resin and other glutinous matters contained in them.
This apparatus is constructed as follows:-Its main portion is a retort
with a perforated partition on which the fibres are laid; the said retort
is also provided with a cover which is made perfectly tight by screwing
it down upon a sheet of india-rubber or by other suitable means. Below
the perforated partition the retort has a tube which communicates with
a vessel wherein chlorine gas is generated in the usual manner, and
from which the gas is introduced into the retort below the fibres. The
said fibres being damp from the previous soaking process absorb the
gas rapidly and are thereby thoroughly bleached. In connection with
the retort is a vacuum chamber into which I conduct the chlorine gas,
and by means of cocks or valves I retain the same therein while the
bleached fibres are being removed and others introduced into the
bleaching retort. By this contrivance all danger of injurious effects
from the chlorine gas is completely obviated. For greater security
against the escape of the gas I construct the retort and vacuum chamber
with a double casing between which I introduce a mixture of india-
rubber, hemp, and tar. When the fibres have been properly bleached,
I place them in a boiler or digester and boil them with an alkaline

page_text: solution preferably formed by dissolving soda ash in chlorine liquor,
using about twelve pounds of soda ash for every hundredweight of fibres.
When the fibres or filaments are of unequal thickness I introduce into
the said alkaline solution a small quantity of protoxide of calcium to
facilitate the action of the alkali. This treatment leaves the fibres in
the condition of a mass of fibrous pulp or half stuff which may be manu-
factured into paper by the ordinary processes.