Improvement in the Manufacture of Colouring Matter.
Year: 1898

page_text: Improvement in the Manufacture of Colouring Matter.
WILLIAM MCCOWAN, of 29, Cathcart Street, Greenock, Analyst, do hereby
declare the nature of this invention to be as follows:-
The object of this invention is the conversion of some carbohydrates into a
colouring material.
In order to carry out this invention I use for convenience glucose or grape
sugar and heat this in a closed vessel with five to ten per cent, by weight of liquor
ammonia specific gravity 880 to about 212° Faherenheit for about twenty four
hours.
It is to be understood that I do not confine myself to any special carbohydrate
as several other carbohydrates react in a similar manner nor to time heat and
quantities as above mentioned.
Improvement in the Manufacture of Colouring Matter.
WILLIAM MCCOWAN, Analyst, 29, Cathcart Street, Greenock, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement-
I take commercial glucose or grape sugar one hundred parts and add to it
from five to ten parts of commercial liquor ammonia 880 specific gravity, both
the above materials to be taken as by weight. It is to be understood that '880
ammonia means any trade variation from this strength and is only used as a
general descriptive commercial product, and that the term glucose or grape
sugar includes the various commercial starch sugars. I introduce the above
materials into a vessel which can be tightly closed (subsequently) called the
convertor) and capable of withstanding the pressure which is produced during
the heating of the above materials. I heat the convertor and contents to about
212° Fahrenheit during a period of about twenty four hours. If the heating
has taken place throughout in a closed vessel the colouring matter may be con-
centrated to a syrup either by opening the closed vessel to allow the vapours to
escape or it may be concentrated in a separate open vessel.
The convertor may be constructed of any convenient shape or size provided
means are taken to have the mixture of grape sugar and ammonia while being

page_text: heated together under proper control as regards temperature and may be made
of iron steel or other suitable material and may be erected either in a horizontal
or vertical position and is to be fitted with manholes for charging, tap for empty-
ing, safety valve, pressure guage, stirring apparatus and other accessories as
would be required depending on the size, strength, position of the convertor and
method of heating the same. The convertor is also fitted with an internal coil
which can be used as a steam coil for heating the contents or can also be used
as a cold water coil to moderate the temperature during the reaction, should the
heat rise beyond the desired point. I prefer a steel or iron convertor for my
purpose the interior metallic surface of the convertor and exterior surface of
the coil having been coated with tin.
The convertor may be heated by immersion in a water bath which is to be
kept at the necessary temperature so as to ensure the heating of the contents of
the convertor to about 212° Fahrenheit, or a steam jacket can be used, or an
internal steam coil to heat the materials as above described. Other sources of
heat may be used but I prefer to use steam or the water bath. Whichever
method of heating is employed it is necessary to have control over the tempera-
ture as it is not advisable to allow the reaction to proceed too rapidly during the
first stage, which may vary from one to three hours. I am well aware that in
working with large quantities the temperature may rise above 212° Fahrenheit
without detriment to the product produced-provided the reaction is not allowed
to proceed too violently nor too far, but I prefer to conduct the operation during
this first stage at the lower temperature viz.: about 212° Fahrenheit. I have
given above the statement that during this first stage the absorption or combina-
tion of the ammonia by or with the grape sugar is completed, this is generally
effected within a period of from one to three hours, depending on the composition
of the carbohydrate under treatment and also as to the management of tempera-
ture. Beyond this stage it is not absolutely necessary to continue the heating
in a closed vessel, the contents of the convertor may be drawn off into an open
vessel and the further heating continued under atmospheric pressure.
It will be found that by heating the combination of grape sugar and ammonia
as above produced in the convertor, in an open vessel, a higher temperature may
be used that is to say if the heat is raised to about 230° Fahrenheit, sufficient
colour will be produced for my purpose in about six hours. If it is required
to operate in an open vessel to finish the colour, I prefer to use a steam jacketed
copper which may be provided with an agitator, but should be fitted with a
cold water coil to regulate the temperature of the contents in the open vessel.
Although I have specifically mentioned glucose or grape sugar I do not confine
myself to this material as I find the following materials give similar results
the sugar known as levulose, the mixture of dextrose and levulose known in com-
merce as invert sugar, maltose and worts or syrups containing all or any of the
above. Nor do I confine myself to the use of liquor ammonia 880 specific gravity
as anhydrous ammonia may be used instead that is to say I would only use the
quantity of anhydrous ammonia which would be equivalent to the ammonia
contained in the from five to ten parts of liquor ammonia .880 specific gravity,
but if anhydrous ammonia is used I prefer to add the weight of the water which
would be contained in the liquor ammonia 880 to the grape sugar before adding
the anhydrous ammonia to the mixture of grape sugar and water in the con-
vertor. Ammonia of considerably less strength than '880 will also answer my
purpose, provided the weaker ammonia employed contains the requisite quantity
of ammonia which should be used as above described.
The syrupy colouring matter as above produced is suitable for most if not
all of the purposes of the substance known as caramel, and I am well aware that
salts of ammonia are used for the purpose of assisting in the manufacture of
what is known as caramel, but no claim is made for the employment of any salt
or compound containing ammonia except as above described. It is to be under-
stood that variations may be made in the quantities, times and temperatures as

page_text: above mentioned without departing from the nature and substance of my
invention.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:-
-
The production of a colouring matter suitable for technical purposes by the
action of ammonia on grape sugar or on any other of the carbohydrates which
reacts under similar conditions substantially as described.
Datad this 20th love of Tul 1800
WILLIAM McCOWAN.