IMPROVE. MENTS IN MANUFACTORING MAGENTA "COLOUR OR DYE."
Year: 1863

page_text: LETTERS PATENT to Dan Dawson, of Milnsbridge Chemical Works,
Huddersfield,. in the County of York, for the Invention of "IMPROVE.
MENTS IN MANUFACTORING MAGENTA "COLOUR OR DYE."
PROVISIONAL SPECIFICATION left by the said Dan Dawson at the
Office of the Commissioners of Patents, with his Petition, on the 12th
January 1863..
I, DAN DAWSON, of Milnsbridge Chemical Works, Huddersfield, in the
County of York, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN MANUFACTURING MAGENTA COLOUR OR DYE," to be as
follows:-
I mix a solution of arsenic acid with aniline in equivalent proportions, so
that a neutral salt of arseniate of aniline is formed; the solution of arsenic
acid is such that it contains from twenty-three to thirty per cent. of water,
including water of hydration. The acid containing twenty-three per cent.. of
water is liable to deposit crystals, but they may be used along, with the mother
liquor, as arseniate of aniline will in this case be formed as well as if the
arsenic acid had been all in solution. When the mixture is made and cooled
it is a solid substance nearly white, having a somewhat crystalline aspect. This
substance contains all the water which held the arsenic acid in solution,
perhaps as water of crystallization. I then put this arseniate of aniline (plus
water) into a strong iron cylinder capable of resisting two hundred pounds

page_text: The
pressure on the square inch. The cylinder is provided with an air-tight fitting
lid in which a pressure gauge is inserted, and I now bolt the lid on.
cylinder being prepared, as above, I place it in a bath capable of being raised
to a temperature of three hundred and fifty degrees to three hundred and sixty
degrees Fahrenheit, by applying heat either by a sand bath or a naked fire;
care must be taken to keep the temperature about three hundred and forty-
five degree or three hundred and fifty degrees Fahrenheit for the space of
about twelve hours. I do not confine myself exactly to twelve hours, as
the time necessary will vary according to the size of the apparatus. The
pressure will get up as high as from seventy pounds to one hundred pounds
on the square inch. I have now produced the colour, and it only needs taking
out of the cylinder and purifying according to any suitable .well-known
method.
What I distinctly claim as new and my.own Invention is, subjecting aniline
and solution of arsenic acid centaining from fourteen to forty per cent. of water
to a temperature of three hundred and twenty degrees to three hundred and
sixty degrees Fahrenheit, and a pressure ranging from twenty pounds to one
hundred and twenty pounds on the square inch. I find that a solution of
arsenic acid containing about twenty-three per cent. of water answers best;
but I claim other proportions of water and acid, as they admit of variation.
The pressure will vary by altering the proportions of acid and water.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Dan Dawson in the Great Seal Patent Office on the 10th
July 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAN
DAWSON, of Milnsbridge Ohemical Works, Huddersfield, in the County of
York, send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of January, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-sixth year of Her
reign, did, for Herself, Her heirs and successors, give. and grant unto me,
the said Dan Dawson, Her special licence that I, the said Dan Dawson,
my executors, administrators, and assigns, or such others as I, the said
Dan Dawson, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make,

page_text: use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN MANUFACTURING MAGENTA' COLOUR OR DYE," upon the condition,
amongst others, that I, the said Dan Dawson, my executors or administra-
tors, 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 Dan Dawson, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, that is to say :-
In carrying out this Invention I mix a solution of arsenic acid with aniline
in equivalent proportions, so that a neutral salt of arseniate of aniline is
formed. The solution of arsenic acid is such that it contains from twenty-.
three to thirty per cent. of water including water of hydration. The acid
containing twenty-three per cent. of water is liable to deposit crystals, but they
may be used along with the mother liquor, as arseniate of aniline will in that
case be formed as well as if the arsenic acid had been all in solution. When
the mixture is made and cooled it is a solid substance nearly white, having a
somewhat crystalline aspect. This substance contains all the water which held
the arsenic acid in solution, perhaps as water of crystallization. I then put
this arseniate of aniline (plus water) into a strong iron cylinder, capable of
resisting a pressure of about two hundred pounds on the square inch. The
cylinder is provided with an air-tight fitting lid in which a pressure guage is
inserted. I now bolt the lid on. The cylinder being prepared, as above, I
place it in a bath capable of being raised up to the temperature of from three
hundred and fifty degrees to three hundred and sixty degrees Fahrenheit. The
bath now raise up to a temperature of about three hundred and forty-five
degrees or three hundred and fifty degrees by applying heat, either by a sand
bath or a naked fire; care must be taken to keep the temperature about three
hundred and forty-five degrees, or three hundred and fifty degrees Fahrenheit
for the space of about twelve hours. I do not confine myself exactly to twelve
hours, as the time necessary for producing the required result will vary according
to the size of the apparatus. The pressure will get up as high as from seventy
pounds to one hundred pounds on the square inch. I have now produced the
color, it only needs taking out of the cylinder and purifying by some well-
known method. The unchanged aniline can be advantageously separated by

page_text: either of the two following processes:-Firstly, by treating with an alkali and
coal tar naphtha, and pouring the mass into a large quantity of water. The.
naphtha rises to the top, having dissolved in it the whole of the aniline.
The aniline can be separated from the naphtha by fractional distillations, or
by treating with an acid; secondly, by adding an alkali or any other suitable
agent to set the aniline free, and distilling with the aid of a current of steam.
Having now. described the nature and object of my said Invention for
Improvements in Manufacturing Magenta Colour or Dye," together with
the manner in which the same is to be or may be performed or carried into
practical effect, I would remark in conclusion that what I distinctly claim as
new and my own Invention is, subjecting aniline and solution of arsenic acid
containing from twenty to forty per cent. of water to a temperature of from
three hundred and twenty degrees to three hundred and sixty degrees Fah-
renheit, and a pressure ranging from twenty pounds to one hundred pounds on
the square inch. I find that a solution of arsenic acid containing about
twenty-three per cent. of water answers best; but I claim other proportions of
water and acid, as it admits of variation. The pressure will vary by altering
the proportions of acid and water.
In witness whereof, I, the said Dan Dawson, have hereunto set my
hand and seal, this Sixteenth day of May, in the year of our Lord
One thousand eight hundred and sixty-three.
DAN DA TISON