IMPROVEMENTS IN THE MANUFACTURE OF COLOURING MATTERS
Year: 1864

page_text: LETTERS PATENT to Charles Lowe, of Bradford Road South, Bradford, near
Manchester, in the County of Lancaster, Manufacturing Chemist, for the
Invention of "IMPROVEMENTS IN THE MANUFACTURE OF COLOURING MATTERS."
Sealed the 13th October 1864, and dated the 10th August 1864.
PROVISIONAL SPECIFICATION left by the said Charles Lowe at the
Office of the Commissioners of Patents, with his Petition, on the 10th
August 1864.
I, CHARLES LOWE, of Bradford Road South, Bradford, near Manchester, in
the County of Lancaster, Manufacturing Chemist, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF
COLOURING MATTERS," to be as follows:-
This Invention consists in the production of brown and red colouring matters
by the reaction taking place between picric acid and commercial aniline,
or a mixture of aniline and toluidine, under the influence of heat.
The proportions that I have found to answer my purpose are as follows:-
1 part by weight of picric acid and 3 parts by weight of aniline, but I do not
confine myself to these, as other proportions and slight variations in the heat
employed will still produce similar results. The mixture must be boiled very
gently for several hours, and then washed repeatedly with boiling coal naptha,

page_text: or benzine, which dissolves out the brown colouring matter. This brown
colouring may be obtained by boiling down the naptha solution to dryness and
treating the residue with boiling dilute hydrochloric acid, to separate any free
aniline it may contain. The red colouring matter may be separated from the
residue insoluble in naptha by first drying such residue, and after washing it
repeatedly with a solution of chloride of sodium, dissolving out the red colour
with alcohol. The alcoholic solution must be filtered and evaporated to
dryness. For dyeing purposes the brown colouring matter must be dissolved
in a caustic alkali or an alkali salt, and the red colouring matter either in
boiling water or alcohol.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Lowe in the Great Seal Patent Office on the
3rd February 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
Lowe, of Bradford Road South, Bradford, near Manchester, in the County of
Lancaster, Manufacturing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tent
_ugust, in the year of our Lord One
thousand eight hundred and sixty-four, in the twenty-eighth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Charles Lowe, Her special license that I, the said Charles Lowe,
my executors, administrators, and assigns, or such others as I, the said Charles
Lowe, 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 THE MANU-
FACTURE OF COLOURING MATTERS," upon the condition (amongst others) that I,
the said Charles Lowe, 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.
NOW KNOW YE, that I, the said Charles Lowe, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-

page_text: formed, to be particularly described and ascertained in and by the following
statement (that is to say) :-
My Invention consists in the production of brown and red colouring matters
by the reaction taking place between picric acid and commercial aniline, or a
mixture of aniline and toluidine, under the influence of heat. "
The proportions that I have found to answer my purpose are one part by
weight of picric acid and three parts by weight of commercial aniline, which I
heat in a suitable vessel for several hours, taking care that the liquid products
given off are condensed and allowed to run back into the vessel in which the
operation is carried on. The reaction takes place at any heat between 212°
Fahrenheit and the boiling point of the aniline, the time occupied varying with
the heat and quantities of material employed. For the proportions given
above in pounds the heat being 360° Fahrenheit, the reaction will be com-
plete in about five hours. When a mixture of pure aniline and toluidine is
used in conjunction with the picric acid, the proportion of this mixture to the
picric acid is the same as when commercial aniline is employed, as likewise is
the mode of treatment. The colouring matter in the melt thus obtained may
be separated by several well known processes, one of which I prefer, and is as
follows:-I place the mixture in a suitable vessel and wash it with benzine
or coal naptha, which dissolves out the brown dye together with any undecom-
posed aniline or toluidine. I then distil off the benzine or coal naptha from
the solution and boil the brown residue in dilute hydrochloric acid of a strength
of 2° Twaddle, to separate the aniline or toluidine. This when dissolved in an
alkali may be employed for dyeing wool and other fibres, threads, and goods.
The residue insoluble in benzine or coal naptha after being boiled with a
solution of common salt to separate any undecomposed picrate of aniline or
toluidine is to be treated with alcohol or acetic acid, to which it gives up the
red dye. I have found two gallons of a saturated solution of common salt
and one gallon of alcohol or acetic acid of ordinary commercial strength are
quantities suitable for a melt obtained from the proportions above named.
These latter solutions may be employed in the ordinary uses of dyeing, or they
may be evaporated to dryness and the golden residue thus obtained can be
used directly in the dye bath.
I wish it to be distinctly understood that I do not confine myself to the
exact proportions or temperatures above mentioned, as they may be varied
without materially affecting the production of the colouring matters; neither
do I claim as new the method of purification of the colours when obtained;
but I claim the production of brown and red colouring matters as herein-
before mentioned by the reaction taking place between picric acid and

page_text: commercial aniline, or a mixture of aniline and toluidine, under the influence
of heat, which colouring matters may be purified by well known processes now
in use.
In witness whereof, I, the said Charles Lowe, have hereunto set my
hand and seal, this Second day of February, in he year of our Lord
One thousand eight hundred and sixty-five.
CHAS. LOWE. (L.S.)