Improvements in the Production of an Indigo Vat or Bath employed in the Dyeing with Indigo.
Year: 1893

page_text: Date of Application, 12th Apr., 1893
Complete Specification Left, 12th Jan., 1894-Accepted, 17th Feb., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Production of an Indigo Vat or Bath employed
in the Dyeing with Indigo.
We READ HOLLIDAY & SONS LIMITED of Upperhead Row, Huddersfield, in
the County of York Manufacturing Chemists and HENRY BINDSCHADLER of
Huddersfield aforesaid, Chemist in the employment of the said Read Holliday &
Sons Limited do hereby declare the nature of this invention to be as follows:-
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This invention relates to the production of an indigo vat or bath by means of
hydrosulphite of soda.
In the dyeing of indigo with hydrosulphite it has been usual to produce a solution
of indigo, by reducing the indigo with hydrosulphite, produced by treating
bisulphite of soda with zinc and adding it to indigo in a fine state of division with
alkali, generally lime in sufficient quantity to dissolve the indigo white produced.
The solution so produced more or less diluted forming the vat at present in use.
The improvement consists in using instead of lime or in addition to other alkalis
recommended caustic soda or potash, in sufficient quantity not only to dissolve the
indigo, but also to redissolve the greater portion or whole of the zinc, precipitated
by the first addition of alkali; thereby producing a clearer vat which when
used for the dyeing of cotton will give a colour different in shade to any hitherto
obtained by the hydrosulphite vat.
The quantity of hydrate of sodium or potassium required being about or over six
molecules to one of indigo, the quantity over six molecules depending on the excess
of hydrosulphite employed for the reduction.
DAL 10th domos Anvil 1802
WM. BROOKES & 'SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Production of an Indigo Vat or Bath employed
in the Dyeing with Indigo.
We READ HOLLIDAY & SONS LIMITED of Upperhead Row, Huddersfield in
the County of York, Manufacturing Chemists, and HENRY BINDSCHADLER of
Huddersfield aforesaid, Chemist, in the employment of the said Read Holliday &
Sons Limited do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement :-
This invention relates to the production of an indigo vat, or bath, by means of
hydrosulphite of soda.
The vat at present in use, more, or less diluted, is usually obtained by reducing
the indigo with hydrosulphite of soda, formed by treating bisulphite of soda with
zinc and adding it to the indigo in a fine state of division with alkali generally lime
in sufficient quantity to dissolve the indigo-white.
The improvement consists in using instead of lime, or in addition to other alkalis
recommended, caustic soda, or potash in sufficient quantity, not only to dissolve the
indigo-white, but also to redissolve the whole, or greater portion of the zinc
precipitated by the first addition of alkali, thereby producing a clearer vat. This
011

page_text: vat when used for dyeing vegetable, or animal fibres will give a colour different in
shade to any hitherto obtained by the hydrosulphite vat.
The quantity of hydrate of sodium, or potassium required being about six
molecules to one of indigo depending on the quantity of hydrosulphite employed
for the reduction.
As an example of the method employed in carrying this invention into effect:
We act upon 345 lbs. of sodium bisulphite of about 20% with 15 lbs. of zinc
preferably zinc dust. After the reduction has taken place, the liquor is run into
270 lbs. of sodium hydrate solution of about 24%. The zinc hydrate is precipitated
and redissolved and a clear reducing solution is obtained. To this we add 77 lbs. of
indigo about 70% previously ground with water into a fine paste, whereby the
latter is reduced and a new solution of indigo suitable for dyeing is formed.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
The production and use of an indigo vat obtained by reducing indigo with
bydrosulphite of soda produced from bisulphite of soda and zinc, using caustic
soda, or potash in sufficient quantity to dissolve the indigo-white formed and to
redissolve the whole, or greater portion of the precipitated, zinc, substantially as
hereinbefore set forth.
Dated
'
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.