Im- PROVEMENTS IN PRODUCING OR PREPARING INDIGO BLUE DYE.
Year: 1873

page_text: LETTERS PATENT to Thomas Dentith, of Manchester, in the County
of Lancaster, Manufacturing Chemist, for the Invention of “Im-
PROVEMENTS IN PRODUCING OR PREPARING INDIGO BLUE DYE.".
PROVEMENTS IN PRODUCING OR PREPARING INDIGO BLUE DYE.”
PROVISIONAL SPECIFICATION left by the said Thomas Dentith at
the Office of the Commissioners of Patents, with his Petition, on
the 23rd October 1873.
f
.
"
I, THOMAS DENTITI, of Manchester, in the County of Lancaster,
Manufacturing Chemist, do hereby declare the nature of the said In-
vention for "IMPROVEMENTS IN PRODUCING OR PREPARING INDIGO BLUE DYE,"
to be as follows
-
>
Firstly. I take the blue indigo of commerce, grind it to a fine.
powder, and mix this powder with a hot solution of either of the
following substances, or with a mixture of two or more of them,
namely, caustic soda, caustic potassa, caustic baryta, caustic lime,
milk of lime, carbonate of soda, soda ash, crude potash, pearl ashes,
black ash, or crude soda; I then add to the mixture a proportionate
)

page_text: quantity of one or more of the following metals in a finely divided
or powdered state, namely, zinc, tin, antimony, bismuth, and iron;
I next heat and agitate by any suitable means, the mixture con-
taining the indigo, the finely divided or powdered metal or metals,
and one or more of the substances above named, and while so heated
and agitated I pass a stream of sulphurous acid gas, or of carbonic
acid gas, or of a mixture of sulphurous acid and carbonic acid gases
into, through, or over the mixture until the indigo loses its natural
blue colour, and passes into the reduced, deoxidized, or soluble state,
this point being ascertained by the ordinary tests; I then allow the
entire mixture to rest, and after the solid matter has subsided I draw
off the liquid containing the reduced, deoxidized, or soluble indigo
into suitable vessels ready for the dyer and printer. Heat is not
absolutely necessary in the preceding operations, but I have found
that the conversion of the blue indigo into the reduced, deoxidized, or
soluble condition is done more quickly and effectively when heat is
applied in the manner specified.
Secondly. I have discovered that I can reduce, deoxidize, or render
soluble the blue indigo of commerce by adding to the mixture of
such blue indigo and other substances, as already stated, instead of
the finely divided or powdered metals already mentioned, hyposulphite,
sulphite, or sulphide of tin, respectively, or one or more of these
compounds, or hypophosphite, phosphite, hypophosphate, or oxalate of
the protoxide of tin, or a mixture of one or more of them; or I add
the protochloride of tin called "single muriate of tin" or the hydrated
stannous oxide, and while hot and agitated subject the mixture in
a closed vessel to the gases already named above. I also find that
I can use instead of these gases a solution of tannic acid, mulic acid,
or other suitable acid or acids, and the blue indigo will be reduced,
deoxidized, or rendered soluble in the manner already. described.
Thirdly. I grind the commercial blue indigo into a paste with water,
and a proportionate quantity of finely divided or powdered zinc, or
any other suitable metal in a finely divided or powdered state; I then
expose this paste in any suitable close vessel or chamber to the action
of burnt sulphur vapour known as sulphurous acid gas, or sulphurous
anhydride, either suitably heated or at common temperatures, till I find
the indigo reduced, deoxidized, and capable of being dissolved in any
of the fore-mentioned alkaline substances or solutions.

page_text: Fourthly. I take the blue indigo in a finely ground state and mix
or suspend it in water; I then add a proportionate weight of the
above-named finely divided or powdered zinc, and heat the mass by
steam or other means, and pass or force through it the burnt sulphur
vapour mentioned above till the indigo is reduced, deoxidized, or rendered
soluble in alkaline liquids."
i
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Dentith in the Great Seal Patent Office on
the 17th April 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
DENTITH, of Manchester, in the County of Lancaster, Manufac-
turing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of October, in the
year of our Lord One thousand eight hundred and seventy-three, in the
thirty-fourth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Thomas Dentith, Her special licence
that I, the said Thomas Dentith, my executors, administrators, and
assigns, or such others as I, the said Thomas Dentith, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN PRODUCING OR PREPARING INDIGO BLUE DYE," upon the condition (amongst
others) that I, the said Thomas Dentith, my executors or administrators,
by an instrument in writing under my, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.

page_text: performed, to be particularly described and ascertained in and by the
following statement (that is to say) :-
I employ the following method or methods either separately or
combined for treating commercial blue indigo, and converting it into
the reduced, deoxydized, and soluble condition suitable for dyeing
and printing, namely,-
Firstly. I take the blue indigo of commerce, grind it to a fine
powder, and mix this powder with a hot solution of cither of the
following substances, or with a mixture of two or more of them,
namely, caustic soda, caustic potassa, caustic baryta, caustic lime,
milk of lime, carbonate of soda, soda ash, crude potash, pearl ashes,
black ash, or crude soda; I then add to the mixture a proportionate
quantity of one or more of the following metals in a finely divided
or powdered state, namely, zinc, tin, antimony, bismuth, and iron;
I next heat and agitate by any suitable means the mixture con-
taining the indigo, the finely divided or powdered metal or metals,
and one or more of the substances above named, and while so heated
and agitated I pass a stream of sulphurous acid gas, or of carbonic
acid gas, or of a mixture of sulphurous acid and carbonic acid gases
into, through, or over the mixture until the indigo loses its natural
blue colour, and passes into the reduced, deoxydised, or soluble state,
this point being ascertained by the ordinary tests; I then allow the
entire mixture to rest, and after the solid matter has subsided I draw
off the liquid containing the reduced, deoxydized, or soluble indigo
into suitable vessels ready for the dyer and printer. Heat is not
absolutely necessary in the preceding operations, but I have found
that the conversion of the blue indigo into the reduced, deoxydized, or
soluble condition is done more quickly and effectively when heat is
applied in the manner specified.
Secondly. I have discovered that I can reduce, deoxydize, or render
soluble the blue indigo of commerce by adding to the mixture of
such blue indigo and other substances, as already stated, instead of
the finely divided or powdered metals already mentioned, hyposulphite,
sulphite, or sulphide of tin respectively, or one or more of these
compounds; or hypophosphite, phosphite, hypophosphate, or oxalate of
the protoxide of tin, or a mixture of one or more of them; or I add
the protochloride of tin called "single muriate of tin," or the hydrated

page_text: stannous oxide, and while hot and agitated subject the. mixture in
a closed vessel to the gases already named above. I also find that
I can use instead of these gases a solution of tannic acid, malic acid,
or other suitable acid or acids, and the blue indigo will be reduced,
deoxydized, or rendered soluble in the manner already described.
Thirdly. I grind the commercial blue indigo into a paste with water,
and a proportionate quantity of finely divided or powdered zinc, or
any other suitable metal in a finely divided or powdered state; I then
expose this paste in any suitable close vessel or chamber to the action
of burnt sulphur vapour, known as sulphurous acid gas, or sulphurous
anhydride, either suitably heated or at common temperatures till I find
the indigo reduced, deoxydized, and capable of being dissolved in any
of the before-mentioned alkaline substances or solutions.
Fourthly. I take the blue indigo in a finely ground state and mix
or suspend it in water; I then add a proportionate weight of the
above-named finely divided or powdered zinc, and heat the mass by
steam or other means, and pass or force through it the burnt sulphur
vapour mentioned above till the indigo is reduced, deoxydised, or rendered
soluble in alkaline liquids.
Having thus fully described the nature of my Invention, and the
manner in which the same is to be performed, I claim as my Invention,
the method and methods of working with the materials named as stated
in paragraphs first, second, third, and fourth of this Specification, for
treating commercial blue indigo and converting it into the reduced,
deoxydised and soluble condition suitable for dyeing and printing.
In witness whereof, I, the said Thomas Dentith, have hereto
set my hand and seal, this Fifteenth day of April One thousand
eight hundred and seventy-four.