Improvements in Dyeing in Dark Blue Shades.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Dyeing in Dark Blue Shades.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby
declare the nature of thus invention (which has been communicated to me fiom
abroad by Leopold Cassella & Company, of Frankfort-on-Main, in the Empire
of Germany,) to be as follows.—
My correspondents have found that dyeings produced with the dyestuff, com-
mercially named "immedial black" which is described in the Provisional Speci-
fication No 25234 of 1897, if treated with peroxide of hydrogen will change
their shade to a dark blue The dyeings thus obtained are distinguished by
their great fastness to washing, acids, light, chlorme, etc
EXAMPLE:
20 kilos. cotton are dyed at a temperature of 80° C in a bath of 400 litres
water containing 1 kilo. immedial black V extra, 08 kilos sodium sulphide
and 12 kilos. of common salt The cotton is allowed to remain in the bath
during about one hour, then lifted and rinsed, then introduced into a second
bath to which 200 grams of peroxide of hydrogen and some ammonia have been
added. The reaction is terminated after treating the cotton for about 1 hour
in this bath at a temperature of about 80° C.
Improvements in Dyeing in Dark Blue Shades.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby
declare the nature of this invention (which has been communicated to me from
abroad by Leopold Cassella & Company, of Frankfort-on-Main, in the Empire
of Germany,) and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement. -
My correspondents have found that dyeings produced with the dyestuff, com-
mercially named "immedial black" which is described in the Patent No 25234
of 1897, if treated with peroxide of hydrogen will change their shade to a dark
blue The dyeings thus obtained are distinguished by their great fastness to
washing, acids, light, chlorine, etc.

page_text: water contaming 1 kilo. immedial black V extra, 08 kilos. sodium sulphide
and 12 kilos. of common salt The cotton as allowed to remain in the bath
during about one hour,, then lifted and insed, then introduced into a second
bath to which 200 grams of peroxide of hydrogen and some ammonia have been
added. The reaction is terminated after treating the cotton for about 1 hour
in this bath at a temperature of about 80° C
In this process peroxide of hydrogen, may be replaced by any compound,
which generates the same such as peroxide of soda o peroxide of barium. If
these bodies are used they are first treated with a suitable quantity of diluted
mineral acid and the developing bath afterwards made weakly alkaline by addı-
tion of ammonia.
In order to produce a bright blue it is necessary to start from a very pure
original colour, which can easily be separated from the crude product of
Patent 25234 of 1897 by precipitating the solution with weak organic acids,
filtering oft, redissolving with some sulphide of sodium and evaporating to a
dry state.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim 18,
The production of fast blue shades by treating dveings obtained with the dye-
stuffs described m the Specification of Patent 25244 of 1897 with peroxide of
hydrogen, substantially as described