AN IMPROVED METHOD OF OBTAINING COLORING MATTERS
Year: 1882

page_text: LETTERS PATENT to Carl Daniel Ekman of Sweden but now of 57 Old
Broad Street in the City of London for an Invention of AN IMPROVED
METHOD OF OBTAINING COLORING MATTERS
PROVISIONAL SPECIFICATION left by the said Carl Daniel Ekman at the
Office of the Commissioners of Patents on the 29th November 1882.
CARL DANIEL EKMAN of Sweden, but now of 57 Old Broad Street in the
City of London "AN IMPROVED METHOD OF OBTAINING COLOURING MATTERS"
The object of this invention is the extraction of colouring matters from the
vegetable substances in which they are contained with a view:-
1 To obtain a larger yield of colouring matter than can be obtained by the
processes bitherto employed and
2nd To obtain the colouring matter in a form generally known as reduced.
8rd To obviate as far as possible (during the process of extraction and evaporation)
the degradation of the colouring matter by oxidation.
4th The treatment of vegetable dye wares, which have already been treated by
one of the known methods with a view to the further extraction of colouring
matter.
The raw material will or will not be required to undergo a preliminary
preparation according to its peculiarities. Compact substances such as dye woods
must be treated by some mechanical mode of disintegration. The one condition
necessary being that during the subsequent process which I am about to describe
the raw material may be easily permeable by the liquid employed.
The raw material in this form is then placed in a suitable vessel or boiler so
constructed that it shall be capable of gradual heating, of sufficient strength to
bear the necessary pressure or tension and, if necessary, lined with lead or other
suitable substance, that it may be capable of resisting the action of the liquid
employed. The vessel or boiler is then charged with the solution or liquid.
The liquid consists of a solution containing sulphurous acid and a base. As to
he base employed I have obtained good results with magnesia, soda, and potash

page_text: but other bases may be used provided that they more or less fulfil the following
conditions:
1 That in presence of sulphurous acid under the conditions employed it has no
deleterious effect on the colouring matters operated upon
2nd When the operation is complete that it shall be of such a nature that it may
be removed from the tinctorial solutions obtained in any suitable form or that its
presence in the extracts may not be objectionable during their subsequent
employment
The boiler or vessel being charged with raw material and solution it is closed
and made tight in the usual way. It is then heated until the pressure exceeds
that of the atmosphere. The degree of beat to which it will be necessary to
expose the contents of the boiler will depend to a considerable extent on the
material operated upon and the more or less perfect extraction of the colouring
matter which may be found desirable.
Under certain circumstances it will be advisable to allow gas and steam to
escape during the boiling operation. The length of time during which it may be
desirable to maintain that pressure will vary according to circumstances After
the boiling operation has been properly performed the liquid will contain the
coloring matters in a reduced form and the solid mass will more or less approach
pure cellulose according to the nature of the material acted upon and the more or
less perfect extraction of the colouring and other matters.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Carl Daniel Ekman in the Great Seal Patent Office on the
28th May 1883.
CARL DANIEL EKMAN of Sweden but now of 571, Old Broad Street in the
City of London "AN IMPROVED METHOD OF OBTAINING COLORING MATTERS "
The invention refers to improvements in the process of producing colouring
matters and its object is the extraction of colouring matters from wood plants or
parts of plants in which they are contained in such a manner as.
1. To obtain a larger yield of colouring matter than can be obtained by the
processes hitherto employed-also
2. To obtain the colouring matter in a more soluble and more stable condition
than that obtained by the usual processes also.
3. To obviate as far as possible (during the process of extraction and
evaporation) the degradation of or injurious effect produced upon the colouring
matter by oxidation.
4. The invention further relates to the treatment of vegetable dyewares which
have already been treated by one of the known methods with a view to the
further extraction of coloring matter.
"
.
The raw material operated upon so as to produce colouring matter will or will no

page_text: be required to undergo a preliminary preparation according to its peculiarities or
the condition in which it is obtained in what may be termed the raw state.
compact substances such as dye woods must be treated by some mechanical mode of
disintegration other materials may be obtained in a sufficiently divided or dis-
integrated condition when in the raw state. The one condition necessary is that
during the subsequent process which I am about to describe the raw material is
treated when in a condition such that it may be easily permeable by the liquid
employed.
The raw material when in a suitably divided or disintegrated state is placed in
a suitable vessel or boiler so constructed that it shall be capable of being.gradually
heated and be of sufficient strength to bear any required steam pressure or tension
and if necessary it should be lined with lead or other suitable substance so that it
may be capable of resisting the action of the liquid employed.-When commencing
the process of producing the colouring matters the boiler is charged with the
solution or liquid and the boiler cover which is as usual made steam tight is closed.
The liquid consists of a solution containing sulphurous acid and a base. As to
the base employed. I have obtained good results with soda and magnesia, but other
bases may be used such as potash provided that they fulfil more or less the
following conditions
1. In presence of sulphurous acid under the conditions employed, the base
employed should have no deleterious effect on the colouring matters operated
upon.
2. When the operation is complete the base should be of such a nature that it
may be removed from the tinctorial solutions obtained in any suitable form or
that its presence in the extracts may not be objectionable during their sub-
sequent employment I have found that soda is the base which may be on the
whole most advantageously employed.
'J
When the boiler or vessel is charged with the raw material and solution and
closed it is then gradually heated until the pressure exceeds that of the atmosphere.
The degree of steam pressure to which it will be requisite to expose the contents
of the boiler will depend to a considerable extent on the nature of the material
operated upon and the more or less perfect extraction of the colouring matters
which may be desirable.
In the treatment of dyewoods (for instance Logwood) if it is desired to obtain
coloring matter containing a small proportion only of the other extractive matters
of the wood it will be advisable in boiling not to exceed a pressure of about 30 lbs
to the square inch; but if the admixture of the other constituents of the wood with
the colouring matter is not objectionable the boiling pressure may be increased
beyond 30 lbs. If Logwood be boiled for about four hours at 90 lbs pressure
nearly the whole of the colouring and incrusting matters will be dissolved so that
a small proportion only will remain in the cellulose. Accordingly it will be at
the option of the operator to use a greater or less pressure according to the
quality of the extract and the shades of color desired.
The proportion of sulphurous acid to base which I have found most advantageous
is about two equivalents of the former to one of the latter or about the proportions
which form the salt commonly called the Bisulphite.
The quantity of chemicals required will mainly depend upon the pressure to
which it is intended to subject the contents of the boiler. When I have boiled at
about 30 lbs I have found a quantity of bisulphite of soda equal to about five
per cent of the dry weight of the dyewood treated give satisfactory results, but
when I have subjected similar dyewood to 90 lbs pressure. I have found it necessary
to increase the quantity of chemicals and in this case have found that about
twenty per cent of bisulphite may be advantageously employed.
When I have treated dyewoods at 30 lbs pressure under the conditions mentioned
above I have obtained the best results by continuing the treatment at that pressure
for about five hours, but when I have used the higher pressure of 90 lbs I have
found a treatment of less than four hours sufficient to produce the desired results.

page_text: The solutions obtained from dyewoods (such as Logwood Brazilwood and
Sapanwood) if the operation of extraction has been properly performed, contain
the colouring matter in an unoxidized condition but the colour effects of these
woods may be produced by suitable mode of developement such as for instance
in the dyeing of wool with logwood extract obtained at 30 lbs pressure under the
conditions above described. In this case the wool may be first mordanted with
chrome or iron and the mordanted wool is then worked in a hot bath consisting of
the above mentioned extract diluted with water. The developement is not so rapid
as with the usual extract consequently the goods may enter the bath at a higher
temperature than usual without fear of producing unevenness in the dye. With a
similar solution good effects are produced on cotton cloth or yarn mordanted with
alumina or iron.
In some cases it may be convenient first partially to extract a portion of the
colouring matter at a low pressure and afterwards to complete the extraction with
a fresh solution at a higher pressure, the two extracts being then of different
qualities and shades,
It will be understood that although I have described above the proportions and
quantities of chemicals, degrees of pressure and duration of treatment which I have
used with good results I do not confine myself to these but what I claim as of my
Invention is.
The method of treating wood, plants or parts of plants containing colouring
matters by subjecting them under steam pressure in a closed boiler to the action of
solutions such as are above mentioned containing sulphurous acid and a base or
alkali substantially as herein described.
In witness whereof I the said Carl Daniel Ekman have hereunto set my
hand and seal the twenty eighth day of May in the year of our Lord One
thousand eight hundred and eighty three.
Witness
WH. SPENCE.
8 Quality Court
Chancery Lane
CARL DANIEL EKMAN (L.S.)