IM- PROVEMENTS IN THE PRODUCTION OF COLORS FOR DYEING OR PRINTING
Year: 1860

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, and of 166, Buchanan Street, in the City of
Glasgow, North Britain, Gentleman, for the Invention of "IMPROVEMENTS
Sealed the 31st July 1860, and dated the 24th March 1860.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 24th March 1860.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, and of 166, Buchanan Street, in the City of Glasgow, North Britain,
Gentleman, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN THE PRODUCTION OF COLORS FOR DYEING OR PRINTING," a communi-
cation to him from abroad from the Company. "L. et E. Boilley, Freres," of
Paris, in the Empire of France, to be as follows:-
This Invention relates to the production from indigo of what the Inventor
calls a "purple blue," and consists, according to one process, of the employ-
ment of the bisulphate of soda for attacking and dissolving the indigo, whereby a
beautiful. "purple blue" is obtained, suitable either for dyeing or printing
purposes.

page_text: Another method of producing the above color consists in attacking the
indigo by means of ordinary sulphuric and phosphoric acid.
A third method consists in using the vapour of anhydrous sulphuric acid
for attacking the indigo.
And, according to a fourth mode or method of producing the "purple blue,"
the indigo is attacked by means of sulphuric acid combined with chloride of
potassium.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Henry Johnson in the Great Seal Patent Office on the
24th September 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex, and
of 166, Buchanan Street, in the City of Glasgow, North Britain, Gentleman,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of March, in the year of our
Lord One thousand eight hundred and sixty, in the twenty-third year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Henry Johnson, Her special license that I, the said
John Henry Johnson, my executors, administrators, and assigns, or such
others as I, the said John Henry Johnson, my executors, administrators, or
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 THE PRODUCTION OF COLORS FOR DYEING OR PRINTING," a
communication from abroad by the Company "L. et E. Boilley, Frères,"
of Paris, in the Empire of France, upon the condition (amongst others) that
I, the said John Henry Johnson, by an instrument in writing under my
hand and seal, 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.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the same.

page_text: is to be performed, to be particularly described and ascertained in and by
the following statement, that is to say :-
The said Invention relates to the production of a new color from indigo,
which color the Inventors term "purple blue," and is applicable to the dyeing
and printing of fabrics.
I will now describe the process by which I obtain the said colour. Take
a quantity of anhydrous bisulphate of soda, from ten to twenty times the
weight of the indigo to be treated. This soda should be subjected to heat
until it fuses, and should be kept in a fused state at a temperature of about
200 to 300 degrees centigrade. In this state the pulverized and sifted indigo
should be gradually added to it, the mixture being constantly stirred to
prevent it from adhering to the bottom of the vessel. This operation may
be effected in any convenient vessel of cast iron, platinum, porcelain, or other
suitable material. The mass swells out, disengages gas, and assumes a dark
color. The operation should be discontinued as soon as the mixture colours
clear water a violet red, and this test should be from time to time employed
in small quantities. By this time the mixture will have become of a pasty
consistency. At this stage the whole mass is thrown into a large quantity of
water, say, seven or eight gallons of water for each pound weight of the
mixture, the whole being well stirred together. To this is now added about
two pounds weight of chloride of sodium or common salt, after which the
whole is allowed to cool, and the product is thrown down in an impure state:
This product is a purple blue of a peculiar kind, which only requires to be
well washed in abundance of salt water to obtain it of the proper purity for
use. In lieu of salt water, any alkaline water in which the blue is not soluble
may be. employed, as, for example, water containing acetate of potash or
chloride of potassium, It only remains to filter the liquid in order to collect
the precipitate, and to dry the same after having removed the matters which
are found on the surface. These matters, which are of a blackish or greenish
color are of another nature, and being of lighter weight they will not be
deposited until the liquid has been allowed to stand some time. The product
thus obtained is in the form of small crystals. The sulphate of soda which
remains in solution in the wash water may be extracted, and ultimately trans-
formed into bisulphate of soda by known methods, so as to enable it to be
used again. The waste salts of soda produced in the preparation of nitric
acid may be employed in conjunction with a suitable quantity of sulphuric
acid to form sulphate of soda, but I claim the anhydrous bisulphate of soda
by whatever process it may be obtained. In place of first fusing the bisul-
phate of soda, and adding thereto the indigo, the two products, either in a

page_text: pulverised or unpulverised state, may be mixed, and heated in crucibles
placed in a furnace, and subjected to a high temperature. Bisulphate of
potash may also be employed in lieu of bisulphate of soda.
This purple blue may also be obtained by the aid of other acids, for
instance, anhydrous phosphoric acid may be added to the sulphuric acid, and
the indigo subjected to the mixture. If the operation is performed cold, the
indigo will not be properly acted before the end of a month; and the operation
is concluded when a violet red is obtained on testing a portion of the material
in water. It then only remains to wash the mass, as before described. By
applying heat the operation is accelerated.
Another mode of operating is to subject powdered indigo to the vapour of
three times its weight of anhydrous sulphuric acid. The vapour is conducted
to it by any suitable mode, and condensed on the indigo which may have been
subjected to the action of Saxe's sulphuric acid. The indigo is left exposed
to the vapor until a portion of the substance placed in water will give a
violet or red. The operation is then stopped, and the product is washed, as
herein-before described.
⚫
Another process consists in subjecting the indigo to the action of chloride
of potassium in combination with anhydrous sulphuric acid. In all these
processes it is necessary to filter the product once dissolved before adding
thereto the marine salt, in order to separate the insoluble matters and the
indigo which may not have been acted on. The purple blue may be likewise
obtained by the bydrated bisulphate in place of the anhydrous bisulphate.
The impure indigo of commerce may be employed in place of pure indigo
in these processes, but the operation in that case will require a longer time
and a higher temperature.
In witness whereof, I, the said John Henry Johnson, have hereunto set
my hand and seal, this Twenty-fourth day of September, One thou-
sand eight hundred and sixty.
J. HENKY JOHNSON.
(L.S.)