IMPROVEMENTS IN THE BLEACHING OF JUTE AND OTHER SUBSTANCES "
Year: 1882

page_text: LETTERS PATENT to Thomas Graham Young of Kelly in the County of
Renfrew, North Britain for an invention of "IMPROVEMENTS IN THE
BLEACHING OF JUTE AND OTHER SUBSTANCES
"
PROVISIONAL SPECIFICATION left by the said Thomas Graham Young at
the Office of the Commissioners of Patents on the 1st April 1882.
THOMAS GRAHAM YOUNG, of Kelly, in the County of Renfrew, North Britain,
"IMPROVEMENTS IN THE BLEACHING OF JUTE AND OTHER SUBSTANCES,"
This Invention which relates to Improvements in the bleaching of Jute and
other substances, consists,―
First. In an Improvement in the present process of "Causticizing" Jute for
paper making, by using instead of Caustic Alkali alone, as is the present practice,
an alkaline Sulphide, Sulphite, Bisulphite, or Hypo Sulphite, either separately or
mixed, with or without the addition of caustic alkali, the object being to combine
the Solvent and softening action of the Alkali with the reducing or deoxidizing
action of the Sulphur. To effect this any soluble unoxidized or partially oxidized
Sulphur compound will answer, but preference is given to the Sulphide of sodiumn
(Na, S) and as a larger proportion of Alkali than Sulphur is required, it is
advisable to add the necessary excess in the form of Caustic Soda (Na Ho).
The conditions under which the causticizing is conducted vary with the nature
of the material under treatment and the purpose to which it is to be applied.-
Fine fibres are best treated cold, inedium fibres by boiling without extra pressure,
coarse fibres by boiling under a pressure of from 15 to 80 lbs.
Second. The Invention consists in the introduction between " causticizing" and
bleaching" of an intermediate treatment with weak acid, which may often be
advantageously combined with free chlorine, but this last is not necessary.-Any
acid will suffice but muriatic or Sulphuric acid are most suitable.The acid is best
used hot provided that the material operated upon be not injured.-The object of
this acid treatment is to destroy any Sulphur compounds left in the fibre, to
dissolve iron and other colouring impurities, and to render the subsequent bleaching
more rapid and efficacious.

page_text: Third. The Invention consists in an Improvement. in the actual "bleaching
process by the use of an Alkaline hypo-chloride other than lime mixed or combined
with an excess of the same or another alkaline base, so as to prevent the formation
of free hypo-chlorous acid or chlorine in the bleaching liquid, preference being
given to the Hypochlorites of Soda and magnesia in conjunction with any soluble
alkaline compound of these bases.
The bleaching Solutions may be made either by partially saturating the. alkaline
base with chlorine, or by a process of "double decomposition" with bleaching
powder, and subsequent addition of an alkali.-In preparing a magnesia Bleach it
is advisable to use the first method and pass chlorine into magnesia and water, in
quantity sufficient to leave 5 to 10% of the magnesia uncombined.-To prepare a
soda bleach in an economical manner Sulphate of Soda is added to a Solution of
Bleaching powder until no further precipitate is produced.-The supernatant liquid
is decanted and the residual lime precipitated by Carbonate of Soda, sufficient
excess of Carbonate or Hydrate of Soda being afterwards added to produce the
required degree of Alkalinity.-The Bleaching Solution thus prepared is ready
for use.
The first precipitate of Hydrated Sulphate of Lime, is an article of Commerce
used by paper makers under the name of "pearl hardening."
Where time is not of special importance it is best to bleach without heat at 60°
Fahrenheit. If the temperature be raised above this point the time is shortened
but the expenditure of Chlorine and loss in weight, are both increased.
The foregoing process refers specially to the bleaching of Jute for paper making,
but is applicable to all other fibres intended for a like purpose.-When however
the Jute or other fibre is intended to be spun or woven, or the bleaching performed
with as little detriment to the fibre as possible," the causticizing" process must be
omitted, and with fine qualities of Jute the acid treatment may also be dispensed
with as also in cases when the final product is not required of the highest attainable
whiteness.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Graham Young in the Great Seal Patent Office on the
30th September 1882.
THOMAS GRAHAM YOUNG of Kelly in the County of Renfrew, North Britain
"IMPROVEMENTS IN THE BLEACHING OF JUTE AND OTHER SUBSTANCES
<<
"
My said invention which relates to improvements in the bleaching of jute and
other substances consists (First). Of an improvement in the present process of
causticizing" jute for paper-making by using instead of caustic alkali alone, as is
the present practice, an alkaline sulphide, with or without the addition of alkali,
the object being to combine the solvent and softening action of the alkali with the
reducing or de-oxidizing action of the sulphur.-To effect this any soluble
unoxidized or partially oxidized sulphur compound will answer, but preference is
given to Sulphide of Sodium or Sulphide of Barium and where a larger proportion
of alkali is required, it is advisable to add the necessary excess in the form of
caustic soda (Na. Ho.) or Baryta
The conditions under which the "causticizing" is conducted vary with the
nature of the fibre under treatment and the purpose to which it is to be applied.-
Fine fibres are best treated cold; medium fibres by boiling without extra pressure ;
coarse fibres by boiling under a pressure of from 15 to 80 lbs. per square inch or
thereabouts.
Second-The invention consists in the introduction between "causticizing" and
"bleaching" of an intermediate treatment with weak acid which may be often
advantageously combined with free chlorine, but this last is not necessary.-Most
acids will suffice but muriatic or sulphuric acid is most suitable-The acid is best
used hot, provided that the material operated upon be not injured.-The object of
this acid treatment is to destroy any sulphur compounds left in the fibre; to
dissolve iron and other colouring impurities and to render the subsequent bleaching
more rapid and efficacious.
"
Third The invention consists in an improvement in the actual "bleaching'
process consisting in the use of an alkaline hypo-chlorite, other than lime, mixed
or combined with an excess of the same or other alkaline base, so as to prevent
the formation of free hypo-chlorous acid or chlorine in the bleaching liquid.-
Preference being given to the hypo-chlorites of soda or magnesia in conjunction
with any soluble alkaline compound of these bases.
"
The bleaching solutions may be made either by partially saturating the alkaline
base with chlorine or by a process of "double decomposition with bleaching-
powder and subsequent addition of an alkali.-In preparing a magnesia bleach it
is advisable to use the first method and pass chlorine into magnesia and water in
quantity such as to leave 5 to 10% of the magnesia uncombined. To prepare a
soda bleach in an economical manner sulphate of soda is added to a solution of
bleaching-powder until no further precipitate is produced.-The supernatant liquid
is decanted and the residual lime precipitated by carbonate or hydrate of soda,
sufficient excess of carbonate or hydrate of soda being afterwards added to produce
the required degree of alkalinity.-The bleaching solution thus prepared is ready
for use.
The first precipitate of hydrated sulphate of lime is a commercial article used
by paper makers under the name of "pearl hardening."
The difference between various samples of jute being so great, the quantity and
strength of the bleaching solution must be regulated according to the nature and
quality of the fibre operated upon.-A solution containing half per cent of available

page_text: chlorine will be found of good working strength but the actual quantity of
chlorine used may vary from 5 to 25% of the weight of the raw jute according
to the coarseness of the fibre and its previous treatment. The more severe the
causticizing" process the less chlorine must be used.
A coarse brown jute, not amenable to any of the present processes for bleaching
may be rendered a fine permanent white by (First) Causticizing for four hours
at 50 lbs pressure of steam per square inch with 5% sodium sulphide and
5% caustic soda and a sufficient quantity of water. (Second). By boiling for
five minutes with water containing 30% of muriatic acid (Third)-By bleaching
with 25 times its weight of alkaline soda bypo-chlorite of the above named
strength.
°
Where time is not of special importance it is best to bleach without heat (at
60° Fahrenheit). If the temperature be raised above this point the time is
shortened but expenditure of chlorine and loss in weight are both increased
The foregoing process refers specially to the bleaching of jute for paper-making
but it is applicable to other fibres intended for a like purpose.
When the jute or other fibre is intended to be span or woven and the bleaching
performed with as little detriment to the fibre as possible, the "causticizing" process
may be omitted and with fine qualities of jute the acid treatment may likewise
be dispensed with, as also it may be dispensed with in cases where the final
product is not required of the highest attainable whiteness.
Cotton linen and other fabrics or mixtures of any of these with Jute, being
more or less injured by the action of chloride of lime or free Chlorine are
advantageously bleached by the foregoing process, omitting the " causticizing"
and acid treatments except in particular cases where either or both may be
necessary.
Having now described and particularly ascertained the nature of my said
invention and the system, mode or manner, in or under which the same is or may
be used or practically 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 herein before in part recited Letters Patent is;
"
First The combined use of an alkali and soluble Sulphide in the process of
'causticizing” jute and other fibrous substances as herein before described.
Second The intermediate treatment with acid as herein before described.
Third The employment of a bleaching solution containing excess of alkali
alone or combined with either or both of the foregoing processes or treatment
claimed in the two preceding claiming clauses and as hereinbefore described
Fourth The bleaching of cotton linen and other fabrics or mixtures of these
with Jute by the process or treatment hereinbefore described.
In Witness Whereof I the said Thomas Graham Young have hereunto set
my hand and seal this twenty ninth day of September in the year of
our Lord One thousand eight hundred and eighty two.
THUMAS GRAHAM YOUNG (L.S.).