IMPROVEMENTS IN THE MANUFACTURE OF COLORING MATTER SUITABLE FOR DYEING AND PRINTING
Year: 1869

page_text: LETTERS PATENT to William Henry Perkin, of Sudbury, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF COLORING MATTER SUITABLE FOR DYEING AND PRINTING."
Sealed the 24th August 1869, and dated the 26th June 1809.
PROVISIONAL SPECIFICATION left by the said William Henry Perkin
at the Office of the Commissioners of Patents, with his Petition,
on the 26th June 1869.
I, WILLIAM HENRY PERKIN, of Sudbury, in the County of Middlesex,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF COLORING MATTER SUITABLE FOR DYEING AND PRINTING,"
to be as follows:-
This Invention has for its object improvements in the manufacture
of coloring matter suitable for dyeing and printing.
The process consists in heating the substance known to chemists as
oxanthracene (a product of the oxidation of anthracene) with con-
centrated or fuming sulphuric acid until a portion of the mixture when

page_text: added to water perfectly dissolves; the resulting product is then diluted
with water and caustic soda or other alkali is added in considerable
excess and until the solution is very strongly alkaline; the solution
is then concentrated and heated up to a temperature of about 200 or
240° centigrade. The product. then changes to a blue or bluish violet
color. The temperature is maintained until the color of the product
ceases to become more intense. The colored mass is then dissolved in
water and acidulated with hydrochloric or other convenient acid which
causes the solution to become yellow and a yellowish precipitate to
form; this precipitate is collected upon a filter, washed with water,
and is then in a suitable condition for use in dyeing and printing in the
same manner as preparations of madder.
In the first operation an excess of sulphuric acid is generally used
(say about one of oxanthracene and 5 of acid), this excess may after-
ards be removed with carbonate of lime or carbonate of baryta, or
in other similar manner, so as to form a diflicult soluble or insoluble
compound with the excess of sulphuric acid, and soluble compounds
with the oxanthracene product. The product is filtered and the solution
treated with carbonate of soda and filtered from the precipitate of
carbonate of lime or baryta which forms. The solution is then con-
centrated and treated with caustic or other alkali until the color is
developed, the operation being conducted and finished as above
described.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Henry Perkin in the Great Seal Patent 2
Office on the 24th December 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENRY PERKIN, of Sudbury, in the County of Middlesex, send greeting.
WHEREAS Her most. Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of June, in the 3
year of our Lord One thousand eight hundred and sixty-nine, in
the thirty-second year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said William Henry Perkin,
Her special licence that I, the said William Henry Perkin, my

page_text: executors, administrators, and assigns, or such others as I, the said
William Henry Perkin, 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 MANUFACTURE OF COLORING
MATTER SUITABLE FOR DYEING AND PRINTING," upon the condition (amongst
others) that I, the said William Henry Perkin, my executors or ad-
ministrators, 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
Scal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent..
NOW KNOW YE, that I, the said William Henry Perkin, do hereby
declare the nature of the said luvention, and in what manner the same.
is to be performed, to be particularly described and ascertained in and
by the following statement thereof (that is to say ):-
This Invention has for its object improvements in the manufacture
of coloring matter suitable for dyeing and printing.
The process consists in heating the substance known to chemists
as oxanthracene (a product of the oxidation of anthracene) with con-
centrated or fuming sulphuric acid until a portion of the mixture when
added to water perfectly dissolves; the resulting product is then diluted
with water, having been by preference freed from excess of acid as
hercin-after described, and caustic soda or other alkali is added to it
in considerable excess and until the solution is very strongly alkaline;
the solution is then concentrated and heated up to a temperature of
about 200° or 240° centigrade. The product then changes to a blue
or bluish violet color. The temperature is maintained until the color
of the product ceases to become more intense. The colored mass is
then dissolved in water and acidulated with hydrochloric or other con-
venient acid which causes the solution to become yellow and a yellowish
precipitate to form; this precipitate is collected upon a filter, washed
with water, and is then in a suitable condition for use in dyeing and
printing in the same manner as preparations of madder.

page_text: In the first operation an excess of sulphuric acid is generally used
(say about one of oxanthracene and five of acid), this excess may after-
wards be removed with carbonate of lime or carbonate of baryta, or in
other similar manner, so as to form a difficult soluble or insoluble
compound with the excess of sulphuric acid, and a soluble compound
or soluble compounds with the oxanthracene product. The product is
filtered and the solution treated with carbonate of soda and filtered
from the precipitate of carbonate of lime or baryta which forms. The
solution is then concentrated and treated with caustic or other alkali
until the color is developed, the operation being conducted and finished
as above described.
In order that the said Invention may be most fully understood and
readily carried into effect, 1 will proceed to describe more in detail
the manner in which I prefer to conduct the manufacture.
I generally carry out this Invention in the following manner-I
take oxanthracene and heat it with sulphuric acid, if the ordinary acid
1 prefer to heat it to near its boiling point, and then add the exan-
thracene by degrees, maintaining the heat until a portion of the mixture
is found to be soluble in water. The proportions I generally use ar
1 part by weight of oxanthracene and 5 parts by weight of sulphuric
acid. If fuming acid be employed I generally mix the acid and
oxanthracene in the proportion of parts by weight of acid to 1 part
by weight of oxanthracene, and heat the mixture up to a temperature
of 180° to 220° until the product is found upon testing a portion of it.
to be soluble in water. The operation should be continued until it is
completely soluble, otherwise a portion of the oxanthracene is wasted.
In performing this operation by either methods glass or other vessels
not casily acted upon by the acid should he employed. The product
obtained either by means of ordinary or fuming sulphuric acid I
dilute with a considerable quantity of water (say 20 times its bulk) and
mix it with sufficient powdered chalk or marble to render the solution
neutral or nearly so, I then filter it from the insoluble sulphate of
lime, washing the residue several times with fresh quantities of water.
The solution thus obtained is then boiled and a solution of carbonate
of soda added until carbonate of lime ceases to be precipitated, the
solution is again filtered or left to stand until the precipitate has
subsided and the clear liquid poured off. This liquid (which is a soda

page_text: salt of the soluble oxanthracene compound) is then evaporated to
dryness or strongly concentrated and then mixed with caustic potash
or soda cither in powder or solution, and in quantity equal to about
one and a half times to twice the weight of the oxanthracene acted
upon. I prefer to use caustic potash or a mixture of caustic potash
and soda, say, in the proportious of 2 parts by weight of potash to one
part of soda. This mixture is then gradually heated up to a tempera-
ture of about 210° to 220°; a lower temperature or a higher one may
be used, but I prefer those mentioned. The heating is continued until
for some time no increase in the intensity of the color has been observed,
this is best seen when a small portion is dissolved in water. Or a better
test is to dissolve a sample of the product in water and add hydrochloric
acid, a yellow precipitate falls and when on a comparison of several
experiments this ceases to become more copious the operation is
complete. The product is then dissolved in water acidulated with
sulphuric, hydrochloric, or other convenient acid and thrown on a filter,
and the precipitate washed until neutral or nearly so. This product
may be used for dyeing and printing in the same manner as preparations
of madder. The coloring matter contained in the yellow filtrate may
be precipitated by neutralizing the solution with carbonate of soda and
allowing it to stand, when it will principally settle down as a dark
colored precipitate, which can be collected upon a filter or otherwise,
and may be used for the preparation of pigments by precipitating its
solution with alumina, baryta, or other base by usual methods, thus
forming pigments or lakes. If it be desired to obtain the more soluble
coloring matter as the chief product, the heating with caustic alkali
should occupy a shorter time, or the amount of alkali used should be
less, say, by one-half; on the other hand if the more soluble coloring
matter has been obtained by mistake, it may be converted into the less
soluble by a second treatment with caustic alkali. Caustic baryta, or
strontia may be used instead of caustic potash or caustic soda with
more or less success, but I much prefer in all cases to use either caustic
potash or a mixture of potash and soda.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood I do not
confine myself to the exact details described, but what I claim is, the
manufacture of coloring matter suitable for dyeing and printing from

page_text: the compound soluble in water which is obtained by heating oxanthra-
cene with sulphuric acid, the said coloring matter being obtained by
the process of heating such soluble compound (or its salt or compound
with a base) with caustic potash or other caustic alkaline substance.
In witness whereof, I, the said William Henry Perkin, have here- i
unto set my hand and seal, this Ninth day of December, in the
year of our Lord One thousand eight hundred and sixty-nine.
W. H. PERKIN. (L.S.)