IMPROVEMENTS IN BLEACHING LINEN AND HEMP THREADS AND TISSUES
Year: 1881

page_text: LETTERS PATENT to Charles Denton Abel, of No. 28, Southampton
Buildings, Chancery Lane, in the County of Middlesex, for an Invention of
"IMPROVEMENTS IN BLEACHING LINEN AND HEMP THREADS AND TISSUES."
A communication from abroad by A. Delabove, of Paris, in the Republic of
France
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel at the
Office of the Commissioners of Patents on the 17th August 1881.
CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane, in
the County of Middlesex. "IMPROVEMENTS IN BLEACHING LINEN AND HEMP
THREADS AND TISSUES." [A communication from abroad by A. Delabove, of
Paris, in the Republic of France.]
These improvements have for their object to obviate entirely the process of
bleaching by exposure of the linen and hemp threads and tissues to the air on
bleaching grounds as heretofore generally practised, the improved process being
applicable whatever be the quality or description of the threads or tissues, and
whether they are in the raw condition or have already been subjected to pre-
paratory chemical treatment.
For this purpose the threads or tissues are first subjected to a series of successive
boilings in alcaline liquors which remove the pectinic substances accompanying the
cellulose, as also the foreign substances remaining from previous treatments, after
which they are passed simultaneously through a solution of chloride of lime and a
solution of sulphate of alumina saturated with hydrate of alumina. These two
substances produce a reaction which liberates ozonised oxygen that possesses a
much greater bleaching power than chloride of lime, even with the addition of
acid, and which has the further advantage of having a much less detrimental effect
upon the fibres than an equivalent quantity of chloride of lime.
The chlorimetrical strength of the solution of chloride of lime to be employed
should vary according as the tissues are more or less dense or are composed of
finer or coarser threads, or are more or less charged with matter requiring

page_text: bleaching action, and consequently according as the bleaching thereof is more or
less difficult. Under any circumstances there is no danger in using a solution of
100 degrees.
The quantity of sulphate of alumina saturated with hydrate of alumina to be
employed will be in a proportion equivalent to the quantity of chloride of lime
used.
The products of the reaction deposited on the fibres are removed by simple
washing.
In order to produce a perfectly white color the threads or tissues that have been
subjected to the above decolorising process are boiled in a soap solution to which is
added ammonia, after which the threads or tissues are subjected to a second
decolorising process similar to the first.
The importance of the above process as an improvement in the bleaching of linen
and hemp will be readily understood. Up to the present time a white color has
only been obtained by the combined action of the air, moisture, and chloride of
lime, the latter body when used alone only giving a yellowish white which does
not satisfy the requirements of trade. Now the said combined action of decolorizing
agents requires repeated exposures on fields, which subject the bleacher to the
uncertainties of the proper atmospheric conditions, whereby the bleaching action is
suspended, sometimes by drought, sometimes by cold, on account of snow covering
the fields. In addition the threads or fabrics are liable to attacks by insects, to
be damaged by high winds and by impurities in the air, and numerous other
disadvantages arising from this method might be mentioned.
By the present improved process the tedious and inconvenient air bleaching
process with its many disadvantages is entirely obviated, and the linen or hemp is
bleached, like cotton fibre by a process which effects a considerable economy in
labor and time, and results in a perfectly regular and reliable manufacture,
obviating all the uncertainties which at present render it impossible for the bleacher
to say when his work will be completed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Denton Abel in the Great Seal Patent Office on the
16th February 1882.
CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane, in
the County of Middlesex. "IMPROVEMENTS IN BLEACHING LINEN AND HEMP
THREADS AND TISSUES." A communication from abroad by A. Delabove, of
Paris, in the Republic of France.
These improvements have for their object to obviate entirely the process of
bleaching by exposure of the linen and hemp threads and tissues to the air on
bleaching grounds as heretofore generally practised, the improved process being
applicable whatever be the quality or description of the threads or tissues, and
whether they are in the raw condition or have already been subjected to pre-
paratory chemical treatment.
For this purpose the threads or tissues are first subjected to a series of successive
boilings in alkaline liquors which remove the pectinic substances accompanying the
cellulose, as also the foreign substances remaining from previous treatments, after
which they are passed simultaneously through a solution of chloride of lime and a
solution of sulphate of alumina saturated with hydrate of alumina. These two
substances produce a reaction which liberates ozonised oxygen that possesses a
much greater bleaching power than chloride of lime, even with the addition of
acid, and which has the further advantage of having a much less detrimental effect
upon the fibres than an equivalent quantity of chloride of lime.
The chlorimetrical strength of the solution of chloride of lime to be employed
should vary according as the tissues are more or less dense or are composed of
finer or coarser threads, or are more or less charged with matter requiring the
bleaching action, and consequently according as the bleaching thereof is more or
less difficult. Under any circumstances there is no danger in using a solution of
100 degrees.
The quantity of sulphate of alumina saturated with hydrate of alumina to be
employed will be in a proportion equivalent to the quantity of chloride of lime
used.
The products of reaction deposited on the fibres are removed by simple washing.
In order to produce a perfectly white colour the threads or tissues that have been
subjected to the above decolourising process are boiled in a soap solution to which
is added ammonia, after which the threads or tissues are subjected to a second
decolourising process similar to the first.
The importance of the above process as an improvement in the bleaching of linen
and hemp will be readily understood. Up to the present time a white colour has
only been obtained by the combined action of the air moisture, and chloride of
lime, the latter body when used alone only giving a yellowish white which does
not satisfy the requirements of trade. Now the said combined action of decolorising
agents requires repeated exposures on fields, which subject the bleacher to the
uncertainties of the proper atmospheric conditions, whereby the bleaching action is
suspended, sometimes by drought, sometimes by cold, on account of snow covering
the fields. In addition the threads or fabrics are liable to attacks by insects, to
be damaged by high winds and by impurities in the air, and numerous other
disadvantages arising from this method might be mentioned.
By the present improved process the tedious and inconvenient air bleaching
process with its many disadvantages is entirely obviated, and the linen or hemp is
bleached, like cotton fibre, by a process which effects a considerable economy in
labour and time, and results in a perfectly regular and reliable manufacture,

page_text: obviating all the uncertainties which at present render it impossible for the bleacher
to say when his work will be completed.
Having thus described the nature of this Invention, and in what manner the
same is to be performed, as communicated to me by my foreign correspondent, I
claim,―
The herein described method of bleaching linen and hemp threads and tissues,
consisting in the treatment of the same with a solution of chloride of lime in
the presence of a solution of aluminium sulphate saturated with hydrate of
alumina.
In witness whereof, I, the said Charles Denton Abel, have hereunto set my
hand and seal, this Sixteenth day of February, in the year of our Lord One
thousand eight hundred and eighty-two.