IMPROVEMENTS IN THE PREPARATION AND BLEACHING OF RAW JUTE AND SIMILAR VEGETABLE FIBROUS MATERIALS, AS WELL AS THE YARN AND WOVEN MATERIAL MANU- FACTURED THEREFROM
Year: 1879

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS IN
THE PREPARATION AND BLEACHING OF RAW JUTE AND SIMILAR VEGETABLE
FIBROUS MATERIALS, AS WELL AS THE YARN AND WOVEN MATERIAL MANU-
FACTURED THEREFROM." A communication from abroad by Anton Girardoni,
of Vienna in the Empire of Austria
Sealed the 17th February 1880, and dated the 20th August 1879.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 20th August 1879.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE PREPARATION AND BLEACHING OF RAW JUTE
AND SIMILAR VEGETABLE FIBROUS MATERIALS, AS WELL AS THE YARN AND WOVEN.
MATERIAL MANUFACTURED THEREFROM." A communication from abroad by Anton
Girardoni, of Vienna, in the Empire of Austria.
According to this Invention the jute or other similar vegetable fibre, either in a
raw condition or as yarn or web, is submitted to a bath containing chromic acid
and acidified with sulphuric acid. The chromic acid extracts hydrogen from the
fibres and the oxide of chromium formed is dissolved by the surplus sulphuric acid,
and the liquid becomes of a green color, the maximum intensity of which indicates
the termination of the process. The dark green solution is then run off and the
fibres washed clean with water. The fibre will then be found to have lost its
harshness or brittleness and to have become more suitable for the purposes of
bleaching and for dyeing or printing. The grey and yellow coloring matter present
in jute fibres presents great difficulties in the ordinary processes of bleaching.
Now according to this Invention the gray coloring matter is removed by the.
employment of a bleaching lye of from two to three degrees Beaumé in strength
consisting of about 100 parts by weight of chloride of lime and forty parts by
weight of calcined soda dissolved in water, or by means of a lye containing hypo-
chlorite, and the yellow dye is removed by submitting the fibres to the action of a
bath containing a permanganate and consisting of about 1 kilogramme of per-
manganate of soda to about one thousand litres of water. After this treatment the
jute is washed with cold water, and any oxide of manganese remaining in or upon
the fibres is removed by the employment of an aqueous solution of sulphurous acid.
The jute is then washed in water and the bleached fibres are dried by exposure to
the air or in a drying chamber.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Seal Patent Office on the 20th
February 1880.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE PREPARATION AND BLEACHING OF RAW JUTE
AND SIMILAR VEGETABLE FIBROUS MATERIALS, AS WELL AS THE YARN AND WOVEN
MATERIAL MANUFACTURED THEREFROM." A communication from abroad by Anton
Girardoni, of Vienna, in the Empire of Austria.
The said Invention relates to the preparation and bleaching of jute and other
similar vegetable fibres, and has reference to the removal of objectionable matter
and a treatment of the fibres, whereby the same are made soft and pliable and have
a silky lustre imparted to them, and at the same time are rendered suitable for
mordanting, dyeing, and bleaching processes without losing any of their strength
or tenacity.
In carrying out the said Invention the jute or other similar vegetable fibre,.
either in a raw condition or in the condition of yarn or woven material, is prepared
by the employment of a bath containing chromic acid acidified with sulphuric acid,
such bath consisting of, say, about 220 gallons of water and from about 10 to 20
pounds of bichromate of soda or potash and from about 7 to 15 pounds of sulphuric
acid. The chromic acid then extracts hydrogen from the fibres and resolves itself
into oxide of chromium and water. The oxide of chromium is dissolved by the
surplus sulphuric acid at the moment of its formation and the liquid becomes of a
green color, the maximum intensity of which indicates the termination of the
process. The dark green solution is then run off and the fibres are afterwards
washed clean with water and will then be found to have lost their brittleness and
harshness.
It is well known that the grey and yellow colouring matter present in juto
fibres presents great difficulties to the ordinary processes of bleaching. Now
according to the said Invention, the grey colouring matter is removed by the
employment of a bleaching lye of a strength of, say, two to three degrees Beaumé
and consisting of, say, about one hundred parts by weight of chloride of lime and
forty parts by weight of calcined soda dissolved in water, or by means of a lye
containing a bypochlorite of an alkali, and the yellow colouring matter which
resists the action of these bleaching materials is removed by submitting the fibres
to the action of a bath containing a permanganate, and consisting of about thirty
five ounces avoirdupois permanganate of soda to about two hundred and twenty
gallons of water, in which this coloring matter is oxidised into a colorless condition.
The fibres are taken out of this bath as soon as the whole of the permanganate of
soda is decomposed and carefully washed with cold water, and any oxide of man-
ganese remaining in or upon the fibres is removed by the employment of an aqueous
solution of sulphurous acid.
As soon as the jute has become white it is again carefully washed and dried by
exposure to the air in a covered space.
Jute and other similar vegetable fibrous materials when prepared and bleached
as hereinbefore described, are adapted by reason of their silky lustre, whiteness, and
pliability, for being dyed or printed with any description of colors.
Having now described and particularly ascertained the nature of the said Inven-
tion and the manner in which the same is or may be used or carried into effect, I
would observe in conclusion that what I consider to be novel and original' and
therefore claim as the Invention secured to me by the hereinbefore in part recited
Letters Patent is :-
The preparation of raw jute and other similar vegetable fibrous materials, or the
yarn and woven material manufactured therefrom, by firstly submitting the same

page_text: to the action of chromic acid and then bleaching the fibres so prepared by means of
an hypochlorite of an alkali or its equivalent, as herein set forth, and also sub-
mitting the fibres so treated to the action of permanganate salts, and to a final
washing with an aqueous solution of sulphurous acid gas, substantially as herein-
before described.
In witness whereof, I, the said John Henry Johnson, have to this my Specifica-
tion set my hand and seal, the Twentieth day of February, One thousand
eight hundred and eighty.
J. HENRY JOHNSON. (L.S.)