AN IMPROVED METHOD OF PRODUCING A YELLOW DYE
Year: 1883

page_text: LETTERS PATENT to Gustav Adolph Bang of the firm of Theodor Bang of
Leeds in the County of York, Export and import merchant for an Invention
of "AN IMPROVED METHOD OF PRODUCING A YELLOW DYE" communicated
to him from abroad by Gustav Adolph Dahl, Ernst Dahl, and Rudolph Dahl.
PROVISIONAL SPECIFICATION left by the said Gustav Adolph Bang at the
Office of the Commissioners of Patents on the 18th April 1883.
GUSTAV ADOLPH BANG of the firm of Theodor Bang of Leeds in the County
of York export and import merchant "AN IMPROVED METHOD OF PRODUCING A
YELLOW DYE." (A communication to me from abroad by Gustav Adolph Dahl,
Ernst Dahl, and Rudolph Dahl trading as Dahl and Company of Barmen in the
German Empire)
One part of alpha-naphtha-methyl-ether is warmed to about 90 degrees centigrade
with four parts of fuming sulphuric acid (containing 10 to 15 per cent. of anhydrous
sulphuric acid) or with eight parts of sulphuric acid of 66 degrees strength so long
that when a sample of the mixture is dissolved in water and warmed with nitric
acid it no longer gives any cloudiness or trace of a precipitate.
When this point is reached the mixture is poured into about ten parts of ice-
water, and two parts of nitric acid are then gradually added and warmed for some
time to about 40 to 50 degrees centigrade. After cooling the mixture solidifies
into a crystalline powder, which is compressed. By treatment with potash a
potassium salt not easily soluble is obtained, thus producing the required dye.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Gustav Adolph Bang in the Great Seal Patent Office on the
18th October 1883.
'
GUSTAV ADOLPH BANG of the firm of Theodor Bang of Leeds in the County
of York, export and import Merchant "AN IMPROVED METHOD OF PRODUCING A
YELLOW DYE" (A communication to me from abroad by Gustav Adolph Dahl,
Ernst Dahl, and Rudolph Dahl, trading as Dahl and Company of Barmen in the
German Empire.)
One part of alpha-naphtha-methyl-ether is warmed to about 90 degrees centigrade
with four parts of fuming sulphuric acid (containing 10 to 15 per cent of anhydrous
sulphuric acid) or with eight parts of sulphuric acid of 66 degrees strength so long
that when a sample of the mixture is dissolved and warmed with nitric acid it no
longer gives any cloudiness or trace of a precipitate.
When this point is reached the mixture is poured into about ten parts of ice-
water, and two parts of nitric acid are then gradually added and warined for some
time to about 40 to 50 degrees centigrade. After cooling, the mixture solidifies
into a crystalline powder, which is compressed.
By treatment with potash a potassium salt, not easily soluble, is obtained, thus
producing the required dye.
Having now described the nature of the said Invention I would have it under-
stood that the quantities and strengths of the various ingredients may be varied
in accordance with the quality or strength of the yellow dye required; what is
claimed is
The method of producing a yellow dye substantially as herein set-forth.
In Witness whereof, I, the said Gustav Adolph Bang have hereunto set
my hand and seal this twenty-third day of August in the year of Our
Lord one thousand eight hundred and eighty three.
AUTOMAT ADOLDU DANA