IMPROVEMENTS IN BLEACHING
Year: 1854

page_text: LETTERS PATENT to Andrew Duncan, of Glen House, Denny, in the
County of Stirling, North Britain, Paper Maker, for the Invention of
"IMPROVEMENTS IN BLEACHING."
Sealed the 2nd June 1854, and dated the 6th February 1854.
PROVISIONAL SPECIFICATION left by the said Andrew Duncan at the
Office of the Commissioners of Patents, with his Petition, on the 6th
February 1854.
I, ANDREW DUNCAN, of Glen House, Denny, in the County of Stirling,
North Britain, Paper Maker, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN BLEACHING" to be as follows:-
This Invention relates to the obtainment of economy of time and superiority
of effect in bleaching textile fabrics, the materials used in the manufacture of
paper, as well as in other processes or manufactures wherein the bleaching
operation is used. It consists in using the bleaching liquid in a heated state.
In the manufacture of paper, for example, the chloride of lime or other solu-
tion employed as the bleaching agent is artificially heated up to a temperature
(of 100 degrees more or less) variable with the nature of the goods, and which
heat is best ascertainable by practical experiment. This heated matter is then

page_text: applied to the materials in the mixing engine, when the necessary effect is
produced without any separate steeping process. Textile fabrics, or other
articles requiring the bleaching process, are similarly treated with a heated
bleaching solution, with corresponding economy of time and excellence of effect.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Andrew Duncan in the Great Seal Patent Office on the
5th August 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
DUNCAN, of Glen House, Denny, in the County of Stirling, North Britain,
Paper Maker, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of February, in the year of our Lord
One thousand eight hundred and fifty-four, in the seventeenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Andrew Duncan, Her special license that I, the said Andrew Duncan,
my executors, administrators, and assigns, or such others as I, the said Andrew
Duncan, 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 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 BLEACHING,"
upon the condition (amongst others) that I, the said Andrew Duncan, by an
instrument in writing under my hand and seal, should particularly describe
and ascertain the nature of the said Invention, and in what manner the sanie
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 Andrew Duncan, 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 accompanying Drawings, and to the letters and
figures marked thereon, that is to say:-
My said Invention relates to the obtainment of economy of time and
superiority of effect in bleaching textile fabrics, the materials capable of being

page_text: used in the manufacture of paper, as well as in other processes or manufac-
tures wherein the bleaching operation is necessary. It consists in the using
the bleaching liquid in a heated state. In the manufacture of paper, for
example, the aqueous solution of chloride of lime or other substance employed
as the bleaching agent is artificially heated up to a temperature of one hun-
dred and ten degrees of Fahrenheit's thermometer, or to a temperature not
far departing from this point, the exact temperature being somewhat variable
with the nature of the fabrics or fibres under treatment. The proper tempera-
ture is best ascertainable by practical experiment. The heated solution is
then applied to the materials in the mixing engine, or other suitable vessel,
with or without the addition of any fresh bleaching liquor, to raise the
strength, when the necessary effect is produced without any separate steeping
process. Textile fabrics, or other articles requiring, the bleaching process, are
similarly treated with an artificially heated bleaching solution, with corre-
sponding economy of time and excellence of effect.
And in order that my said Invention may be properly understood, I shall
now proceed to describe the Figures on my Sheet of Drawings hereunto
attached.
Figure 1 on my Sheet of Drawings is a vertical section of the stone
chamber or receiver, in which the preparatory heating of the bleaching agent
is effected, shewing the heating steam pipes in the bottom thereof.
Figure 2 is a corresponding plan of the heating vessel, with the heating
pipes also in plan in the bottom. The cylindrical: stone vessel A, employed
for holding the bleaching liquid as shewn deposited up to the level B, is con-
veniently arranged in the paper works, so as to be easily manageable in com-
bination with the "poaching engine," or other vessels used for bleaching. A
steam pipe C enters it on one side from a boiler, the flow of steam along this
pipe being governable by a stop-cock .D. The pipe C is continued forward
through the thickness of the vessel's side, and it is coupled at E to the central
branch of a copper pipe F. This copper pipe F, together with the opposite
corresponding pipe G, and the intermediate smaller tubes II, form what I call
a "gridiron heater." From the first pipe F the steam has a clear passage
along, and through the whole of the tubes II, into the opposite pipe G, and
thence through the central branch I and coupling J, into the efflux or waste
steam and condensed water discharge pipe K. This heater is disposed near
to and parallel with the bottom of the vessel, and as the steam is spread or
diffused by it over a very great extent of acting surface, the liquid "bleach"
contained in the vessel is heated to the required temperature in the most

page_text: economical manner. When sufficiently heated, the bleaching agent is dis-
charged from the vessel A, through the wide pipe M opening into the bottom
of the chamber at N. The small conical lift valve at O is simply for clearing
out the chamber, when it is required to be absolutely emptied and cleansed.
The after process of applying this heated bleaching agent may be similar to
that hitherto pursued in the ordinary system of bleaching, whether, as I have
herein supposed, the "bleach" is discharged into the pulpy mass for the
manufacture of paper, or applied to manufactured goods or textile materials,
and in the event of the weak liquor, or totally or partially exhausted liquors
not being re-used in the bleaching process, water should be heated to the
temperature aforesaid, and the necessary quantity of fresh bleaching liquid
added to it, so as to yield a solution of the required strength and temperature.
By the adoption of this system of treatment, the time occupied in bleaching
fabrics or fibres is very greatly reduced, whilst by it hard and intractable
qualities of rags or fibres used in the manufacture of paper may be easily
decolorized, and the difficulty arising from the presence of "sheaves" is
avoided. The routine of treatment which I have found to be best suited for
carrying out my Invention, in practice, as regards the more ordinary materials
for paper making is, first, the heating the waste bleaching liquor in the
chamber, which I have herein-before described, then supplying this heated
waste or partially or totally spent liquid, to the pulpy mass, or vice versâ,
allowing the materials to be thoroughly admixed, and finally adding strong
bleaching liquor of the required strength and quantity in a cold state. By
thus carrying out the process of bleaching, I am enabled to produce a very
superior effect without the use of "steeps," and hence I obtain very great
economy in the time taken up by the process.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my Invention; but what I
consider to be novel and original, and therefore claim as the Invention secured
to me by the herein-before in part recited Letters Patent, is,-
First, the system or mode of bleaching the materials capable of being used
in the manufacture of paper, textile materials, and other substances or fabrics,
by the agency of a separately heated bleaching liquid.
Second, the application and use in bleaching of a bleaching liquid or agent

page_text: separately heated to one hundred and ten degrees on Fahrenheit's scale, or to
a temperature not far departing from this point.
Third, the system or mode of effecting the bleaching process without the
use of "steeps," as herein-before described.
In witness whereof, I, the said Andrew Duncan, have hereunto set my
hand and seal, this Second day of August, in the year of our Lord
One thousand eight hundred and fifty-four.
AN. DUNCAN. (L.S.)