IMPROVEMENTS IN BLEACHING CERTAIN VEGETABLE FIBRES USED FOR TEXTILE OR OTHER PURPOSES, WHETHER IN THE RAW STATE OR MANUFACTURED
Year: 1863

page_text: LETTERS PATENT to Alexander Robertson Arrott, of Saint Helen's, in
tho County of Lancaster, Chemist, for the Invention of "IMPROVEMENTS
IN BLEACHING CERTAIN VEGETABLE FIBRES USED FOR TEXTILE OR OTHER
PURPOSES, WHETHER IN THE RAW STATE OR MANUFACTURED."
Sealed the 10th November 1863, and dated the 31st July 1863.
PROVISIONAL SPECIFICATION left by the said Alexander Robertson
Arrott at the Office of the Commissioners of Patents, with his Petition,
on the 31st July 1868.
I, ALEXANDER ROBERTSON ARROTT, of Saint Helen's, in the County of
Lancaster, Chemist, do hereby declare the nature of the Invention for "IM-
PROVEMENTS IN BLEACHING CERTAIN VEGETABLE FIBRES USED FOR TEXTILE OR
OTHER PURPOSES, WHETHER IN THE RAW STATE OR MANUFACTURED," to be as
follows:-
In the ordinary process of bleaching, the substance to be bleached, after
being subjected to a preparatory process consisting principally of boiling with
a solution containing soda or lime, whereby certain matters are removed, is
steeped in a solution containing chloride of lime, though other chlorides are
sometimes used, and when it has become sufficiently impregnated with this

page_text: solution it is immersed in a dilute acid. by which means chlorine is liberated,
the coloring matter is destroyed, and the substance becomes white or bleached
by the action of the free chlorine. By using this method of bleaching a con-
siderable loss of weight in the substance results, and in some cases a good
white color cannot be obtained without a very considerable loss in weight and
diminution in the strength of the fibre. Now I have discovered that vegetable
fibres used for textile or other purposes may be bleached with less loss in
weight and less loss in strength of fibre by using for this purpose a solution
containing a chloride and an alkali or its carbonate or alkaline earth, the
bleaching being completed in this liquid and the use of free chlorine
.altogether avoided. The strength of the solution varies with the nature of
the fibre to be bleached, but a solution containing from 200 to 300 grains
of chlorine per gallon is found suitable for most fibres. The amount of alkali
is also determined by the nature of the fibre, a very small quantity being used
in some cases, and in others a comparatively strong alkaline ley.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Robertson Arrott in the Great Seal Patent Office
on the 28th January 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
ROBERTSON ARROTT, of Saint Helen's, in the County of Lancaster, Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirty-first day of July, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-seventh year of
Пer reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Alexander Robertson Arrott, Her special licence that I, the
said Alexander Robertson Arrott, my exccutors, administrators, and assigns,
or such others as I, the said Alexander Robertson Arrott, my 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 BLEACHING CERTAIN
VEGETABLE FIBRES USED FOR TEXTILE OR OTHER PURPOSES, WHETHER IN THE RAW
STATE OR MANUFACTURED," upon the condition (amongst others) that I, the

page_text: said Alexander Robertson Arrott, 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 Alexander Robertson Arrott, 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 thereof, that is to say:-
In the ordinary process of bleaching, the substance to be bleached, after
being subjected to a preparatory process consisting principally of boiling with a
solution containing soda or lime, whereby certain matters are removed, is
steeped in a solution containing chloride of lime, though other chlorides arc
sometimes used, and when it has become sufficiently impregnated with this
solution it is immersed in a dilute acid, by which means chlorine is liberated,
the coloring matter is destroyed, and the substance becomes white or bleached
by the action of the free chlorine. By using this method of bleaching a con-
siderable loss of weight in the substance results, and in some cases a good
white colour cannot be obtained without a very considerable loss in weight and
diminution in the strength of the fibre. Now I have discovered that vegetable
fibres used for textile or other purposes may be bleached with less loss in
weight and less loss in strength of fibre by using for this purpose a solution
containing a bleaching chloride and an alkali, the bleaching being completed
in this liquid and the use of free chlorine altogether avoided.
My Invention is applicable to the bleaching of flax, hemp, jute, cotton, or
other vegetable material used as a textile material, or for the manufacture of
paper, and the manner in which I prefer to proceed in carrying the said
Invention into effect is as follows:-
I prepare a solution of a chloride of an alkali containing in addition to the
alkali in combination with chlorine a certain amount of caustic alkali, and I
prefer for bleaching flax, hemp, or cotton that this caustic alkali should be at
least in proportion to the amount of chlorine in the solution as 5 to 100,
but in the bleaching of jute and similar materials where much extraneous
matter has to be removed, the proportion of caustic alkali present may be
largely increased with advantage even to the extent of 25 to 100, and in any
case the amount of caustic alkali in the solution may be such as would not
affect the strength of the material if exposed to its action during the time

page_text: necessary for bleaching, supposing no chlorine to be used at the same time.
The strength of the bleaching liquid will vary with the nature of the material
to be bleached and the temperature at which the process is carried on, high
temperatures requiring weaker liquids. The temperaturo I prefer is 80°
to 100° of Fahrenheit, and the liquid I prefer to use at this temperature
contains 200 to 300 grains of chlorine per gallon, though for some materials
where the fibro is strong this quantity may be increased with advantage.
There are many methods of preparing the bleaching liquid, one of the most
convenient is by passing chlorine into a solution of caustic alkali, whereby
chloride of the alkali is produced, and adding just such an amount of chlorine
as will leave a sufficient quantity of the alkali in a caustic state along with
the chloride produced, the proportions of these being regulated according to
the nature of the material to be bleached. Or bleaching powder may be
decomposed by means of carbonate of soda or of potash, a quantity of this
being added beyond the amount required to decompose the chloride of lime
present in the bleaching powder; the free lime which is always present to some
extent in the bleaching powder converts this excess of carbonate of soda or
potash into caustic alkali, but if this excess of lime is not sufficient to causticise
the excess of carbonate of soda or potash, lime must be added to the mixture
of carbonate of soda or potash and bleaching powder to produce this
cffect. In place of using carbonate of soda or potash to decompose the
chloride of lime, sulphate of soda or potash may be used and carbonate
added only in sufficient quantity to produce the necessary amount of caustic
alkali.
Having prepared a bleaching liquid of proper strength as before described,
I place it in a suitable vessel and steep the material to be bleached in it, taking
care that all parts are equally acted on, which can be accomplished by any of
the well known methods in use in the ordinary process of bleaching, and if a
sufficiently quantity of bleaching liquid is used the process may be completed
in one operation; but as after some time the action becomes slow, I prefer to
remove the material to a quantity of fresh liquid, or to draw off the partially
exhausted liquid and replace it by fresh liquid, and this change should be
repeated till the desired amount of bleaching is obtained; fresh material
requiring to be bleached is then immersed in the partially exhausted liquid, so
that the remaining chlorine may be utilized. The quantity of chlorine required
to bleach a certain weight of material is about 10 to 15 per cent of its weight,
but this will vary with the nature of the material to be bleached and the
degree of whiteness required. When the material has become of tho desired

page_text: degree of whiteness it should be removed from the liquid and thoroughly
washed and dried in the manner usually adopted.
In witness whereof, I, the said Alexander Robertson Arrott, have
hereunto set my hand and seal, this Twenty-seventh day of January,
in the
year of our Lord One thousand eight hundred and sixty-four.
A. R. ARROTT. (L.B.)