IMPROVEMENTS IN THE MANUFACTURE OF PAPER, OR IN THE MACHINERY EMPLOYED THEREIN, AND IN THE PROCESS OF BLEACHING PAPER, LINEN, AND OTHER MANUFACTURES IN WHICH CHLORIDE OF LIME IS EMPLOYED
Year: 1846

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DONKIN, of Grange Road, Bermondsey, in the County of Surrey, Civil
Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Fifteenth day of
October, in the tenth year of Her reign, did give and grant unto me, the
said John Donkin, my executors, administrators, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said John Donkin,
my executors, administrators, and assigns, and such others as I, the said John
Donkin, my executors, administrators, or assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during the
term of years therein mentioned, should and lawfully might make, use,
exercise, and vend, within that part of the United Kingdom of Great Britain
and Ireland called England, Her Dominion of Wales, and Town of Berwick-
upon-Tweed, my Invention of "IMPROVEMENTS IN THE MANUFACTURE OF PAPER,
OR IN THE MACHINERY EMPLOYED THEREIN, AND IN THE PROCESS OF BLEACHING
PAPER, LINEN, AND OTHER MANUFACTURES IN WHICH CHLORIDE OF LIME IS
EMPLOYED;" in which said Letters Patent there is contained a proviso requiring
that I, the said John Donkin, shall particularly describe and ascertain the
nature of my said Invention, and in what manner the same is to be performed,
by an instrument in writing under my hand and seal, and cause the same to

page_text: be enrolled in Her said Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said in part recited Letters
Patent, as, reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
John Donkin, do hereby declare that the nature of my Invention, and the
manner in which the same is to be performed, are particularly described and
ascertained in and by this present Specification or Instrument in writing under
my hand and seal (that is to say):-
My said Invention consists of improvements in that part of the manufacture
of paper which relates to the bleaching of the pulp or material which is to
be manufactured into paper, and which improvements are also applicable to
other manufactures in which chloride of lime is employed for bleaching.
When chloride of lime has been used for bleaching paper pulp, or any other
fabric or material, it is generally desirable to get rid of it as soon as possible
after it has produced the desired bleaching effect; but when paper pulp or
any textile fabric has once been thoroughly mixed or saturated with the
chloride of lime, it generally requires a long and troublesome operation in
order to get rid of it. The mode in which I get rid of the chloride of lime is,
after the paper pulp or other material has had the greater part of the liquid
chloride of lime drained or pressed out of it, I mix the paper pulp or other
material with a chemical agent which will decompose the chloride of lime;
the new substance or substances produced being such as will not produce any
injurious effects upon the article which has just been bleached. The chemical
agent which I employ for that purpose is usually called by chemists bi-
sulphite of soda, and although sulphite of soda will decompose chloride of
lime, yet it will not, I believe, produce so beneficial an effect for the purposes
of my Invention as the bisulphite of soda. The bisulphite of soda is not,
I believe, a usual article of commerce, but it may be made by any of the
processes known to chemists as applicable for that purpose. The mode which
I have adopted and found to succeed for the manufacturing of this article are
the following:-One method is by exposing thin layers of dried soda (of
commerce) to sulphurous acid gas, either produced from burning sulphur or
otherwise, so that the soda may combine with the sulphurous acid to such an
extent as to form the bisulphite of soda, which will in this mode be produced
in a dry or solid state. Another method is to dissolve the soda of commerce
in water, and then pass sulphurous acid gas through or into the solution until
the soda becomes a bisulphite, and the solution may in this case be made
more or less saturated as may be desired; and if the solution be made
moderately warm and sufficiently saturated the liquid will upon cooling deposit

page_text: crystals of bisulphite of soda. I have, however, only stated those methods of
making bisulphite of soda by way of illustration, and I do not confine myself
to the use of bi-sulphite of soda made by these methods, or either of them. In
the manufacture of paper. it is usual to apply the chloride of lime to the pulp
when it is in the state called half stuff, that is, before the process of separating
or dividing the fibres of the paper stuff has been completed, and this is done
because the process of washing the chloride of lime out of the stuff or pulp when
in a minutely divided state would carry off or waste much of the pulp itself. But
when working according to my improved method, the usual process of washing
out the bleaching liquid is generally dispensed with, and therefore the paper
maker may make his pulp much finer before bleaching it, and thus the bleach-
ing liquid will be enabled to act more efficiently upon the pulp. When paper
pulp of any degree of fineness has been bleached by liquid chloride of lime,
I allow the greater portion of the liquor to drain from it, and if convenient it
will be still better to press it, so as to express as much of the liquid as practible
from the pulp. The bleached pulp is then to be thrown into water, and a
sufficient quantity of bisulphite of soda added gradually to, and thoroughly
mixed with it, so as to decompose the whole of the chloride of lime which may
happen to remain mixed with the pulp; and the quantity of bisulphite of
soda required will of course vary according to circumstances, as the manufac-
turer may have used more or less chloride of lime in the process of bleaching,
or as the bleaching liquid may have been more or less drained or pressed from
the pulp; but I have in practice found that about a pound of the saturated
solution of bisulphite of soda is sufficient for decomposing the chloride of lime
in the pulp obtained from a hundred weight of rags when the pulp has been
well drained or pressed. This operation of decomposing the chloride of lime
remaining in the pulp I perform when the pulp has been introduced into the
engine for the purpose of completing the process of dividing the pulp, and
making it sufficiently firm to be made into paper. The effect produced by the
addition of bisulphite of soda to the chloride of lime is, I believe, to cause a
double decomposition, and to produce two new compounds, that is, inuriate of
soda and sulphate of lime. The sulphate of lime is insoluble, or nearly so,
but the quantity being very small it will not be injurious to the paper, and the
muriate of soda will all be carried away with the water, or nearly so. In order
to apply my Invention to linen, or any other article which has been subjected to
the action of chloride of lime to be bleached, I deprive it of as much of the
solution of chloride of lime as practicable or convenient, by draining, pressing,
or otherwise, and I then throw it into water, adding thereto a sufficient
quantity of bisulphite of soda to decompose the remaining chloride of lime

page_text: which may remain mixed with or adhering to the article, in like manner as
herein-before described with respect to my method of treating bleached pulp,
or a solution of the bisulphite may be applied to a bleached article in any
other manner which may be found more convenient.
Having now described the nature of my said Invention, and the manner in
which the same is to be performed, I hereby declare that I claim as of my Inven-
tion the application of bisulphite of soda in solution to paper pulp, linen, and
other articles or materials which have been bleached by means of chloride of
lime, so as to decompose and get rid of the chloride of lime which may be
remaining mixed therewith or attached thereto in manner and for the purposes
herein-before described.
In witness whereof, I, the said John Donkin, have hereunto set my
hand and seal, this Twenty-third day of March, in the year of our
Lord One thousand eight hundred and forty-seven.

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DONKIN, of Grange Road, Bermondsey, in the County of Surrey, Civil
Engineer, send greeting.
WHEREAS by Letters Patent under the Great Seal of the United
Kingdom, bearing date at Westminster, the Fifteenth day of October, in
the tenth year of Her present Majesty's Reign, Her said Majesty did grant
to me, my executors, administrators, and assigns, the sole privilege of mak-
ing, using, working, and vending my Invention, which is therein entituled
"IMPROVEMENTS IN THE MANUFACTURE OF PAPER, OR IN THE MACHINERY EMPLOYED
THEREIN, AND IN THE PROCESS OF BLEACHING PAPER, LINEN, AND OTHER MANU-
FACTURES IN WHICH CHLORIDE OF LIME IS EMPLOYED," within England, Wales,
and Berwick-upon-Tweed, during the term of fourteen years from the date of
the said Letters Patent next ensuing; and whereas since obtaining the said
Letters Patent I have discovered that so much of the said Invention as relates
to certain machinery is not of much utility, and that the process of bleaching
mentioned in the title of the said Invention cannot with much benefit be
applied to the bleaching of paper after it has been manufactured; and I am
therefore desirous, with the leave of Her Majesty's Solicitor General, to enter
with the Clerk of the Patents in England such Disclaimer as herein-after
contained or expressed.
NOW KNOW YE therefore, that by and with the leave and consent of
Sir David Dundas, Knight, Her Majesty's Solicitor General, I, the said John
Donkin, do hereby, for the reasons aforesaid, disclaim so much of the said title
as follows (that is to say):-
The words "or the machinery employed therein," and of the words "in the
process of bleaching paper, linen, and other manufactures," contained in the
said title. I do hereby for the reasons aforesaid also disclaim the word
"paper;" and I do hereby, with such leave as aforesaid, and for the reasons
aforesaid, alter the said title, so that the same shall henceforth be and be
deemed to be "Improvements in the Manufacture of Paper, and in the Process
of Bleaching Linen and other Manufactures in which Chloride of Lime is
employed." And I, the said John Donkin, do hereby declare that the above-
written Disclaimer is not intended to extend the exclusive right granted by

page_text: the said Letters Patents, and that these presents shall not extend the said
exclusive right in any way whatsoever.
In witness whereof, I, the said John Donkin, have hereunto set my hand
and seal, this Twenty-second day of March, in the year of our Lord
One thousand eight hundred and forty-seven.
Temple,
March 23rd, 1847.
DAVID DUNDAS.
23rd March, 1847.
Entered and filed with the Clerk of the Patents. (L.S.)
Inrolled the Seventh day of April, in the year above-written.