Processes for Preserving and Removing or Recovering the Colouring Matters from Tanning and other Vegetable.
Year: 1889

page_text: Date of Application, 1st Oct., 1889
Complete Specification Left, 1st Aug., 1890-Accepted, 6th Sept, 1890
PROVISIONAL SPECIFICATION.
Processes for Preserving and Removing or Recovering the Colouring
Matters from Tanning and other Vegetable. Extracts.
We BENJAMIN NICHOLSON of The Torrs South Norwood in the County of Surrey
Gentleman and THOMAS PALMER B. Sc. of 85 Wool Exchange in the City of
London Analytical and Consulting Chemist do hereby declare the nature of this
invention to be as follows:-
The object of this invention is to effect the decolourizing and preservation of
tanning extracts and other vegetable extracts in a more efficient and perfect manner
than hitherto.
The process according to the invention. is
more especially designed for the
decolourizing of tanning extracts as by it we effect the decolourization of such
extracts without the loss of tannin or of those gums or resinous bodies' which are
advantages in the process of tanning which loss has resulted from the use of the means
hitherto used for decolourizing.
The said process according to this invention also includes a treatment destined
to preserve the tannin and gums.or resinous bodies and prevent destructive growths
or developements.
This invention is particularly useful in cases where extracts are prepared from
hemlock as although it is very advantageous in respect to its weight giving qualities
it is objectionable on account of its possessing in addition to the gums and resins
which are desirable a peculiarly tenacious colouring matter which imparts to the
leather tanned with hemlock a deep red tinge. This invention enables this
colouring matter to be removed without removing the gums and resins which it is
desirable to retain.
According to this invention there is added to the cold extract liquor in order to
effect the removal of the colouring matter a substance capable of oxidation when
brought into contact with a current of air in the presence of water. Nearly all the
oily bodies of the camphoraceous or terpene series are suitable. Such substances
possess the property of causing the precipitation or removal of the objectionable
colouring matter without removing the beneficial gums or resins. A suitable
substance is present in the bark of a plant or tree found in Mexico and called
Cayota" which possesses also a considerable amount of tannic acid.
In addition to, or in substitution for, the Cayota bark we may also use oil of
turpentine either in its crude state or oxidized by a current of air in the presence of
water. We also add for the purpose of preserving the extracts a solution of biniodide
of mercury in an alkaline iodide to which is added hydrochloric acid. The liquors
with these materials added thereto are subjected to a current of air. This current of
air may be either forced or drawn through the vessel. 'Wo generally prefer to force
the air as then we can conveniently recover the products which pass out with the
air. The substance capable of oxidation as aforesaid splits up in becoming oxidized
a portion being taken up by the aqueous solution whilst the heavier oxidized
products combine with the objectionable colouring matter and cause it to
precipitate. It may be removed by causing the liquor to pass through a damp
filter. The liquor may thereafter be still further decolourized by adding to 'it a
solution of alum.
•
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In addition to the materials aforesaid we may add a substance or substances having
an affinity for the camphoraceous or other bodies produced during the aforesaid
oxidation such as for instance-sea water, milk albumen, blood, serum, borax-solution,
dextrin, herring-brine; amides or the like. "The oil may be recovered by adding water

page_text: heating and filtering or when turpentine has been used by shaking up the liquor with
petroleum, ether, or other solvent as for example light turpentine, light petroleum
ether benzoline or the like which distils off at any temperature up to 120° Fahrenheit.
After standing a distinct separation takes place owing to the difference in gravity and
the two portions may be removed separately. The light. portion may be washed with
water and separated and the washings which will contain small quantities of tannin
may be added to the extract liquor and with them pass to the vacuum pans for final
concentration. The remainder or lighter portion may be distilled off forming a clear
light spirit which condenses rapidly and which may be used over and over again for
the recovery of subsequent portions of oil and also a heavy colloidal body which
consists of an oxidized oily body containing a large amount of camphoric peroxide
and other powerful antiseptic bodies and also the colouring matter removed from the
extract.
The said oily body may be fined with turpentine and reused or it may be
washed under a current of hot water or steam and the resulting product be used
either as a soap ingredient for mixture with varnishes or as an antiseptic or
preservative compound.
Further decolourization of the tanning liquor may be effectually carried out prior
to the filtration of such liquor by adding thereto a solution of potassium alum the
whole of the liquor must then be heated up to the temperature to which the original
liquor or any part thereof had been heated in the process of exhaustion such heat being
maintained during the process of filtration. In this manner the whole or by far the
larger proportion of the gums resins and the like are brought into such a state that
they readily pass through a close paper filter.
The process of concentration should be conducted under vacuum.
We may use as preservatives also hydrogen dioxide napthol notably beta napthol
sulphurous acid, mercuric-perchloride corrosive sublimate, thymol, or sulphurous
acid, any one or more of them..
For the decolorization of certain extracts notably the chestnut chataigner
oak wood quebracho Mimosa and the like we may proceed as follows:-To the cold
liquor issuing from the leaches we add petroleum ether or a heavier distilate
of petroleum turpentine or the like (with or without the addition of such other
bodies as potash alum, blood, serum dextrine milk or the like, and shake well up with
a proper equivalent of air, after which the liquor is allowed to separate at as low
a temperature above freezing point as possible. After standing a distinct separation
takes place owing to the difference in gravity and the two portions may be removed
separately. The light portion which is in the form of a jelly may be washed with
water and separated and the washings which will contain small quantities of tannin
may be added to the liquor and with it pass to the vacuum paus for final
concentration. In some instances it may be desirable to continue the process of
decolorization by heating the liquor to boiling point and subsequently filtering before
sending to the concentrators. The process of sterilization to be carried out by
one or either of the afore mentioned substances or materials should be effected just before
concentration.
Further decolorization may be effected by slightly acidifying the liquor by means
of an acid such as hydrochloric acid.
The jelly after washing may now be distilled when the spirit will be regained
leaving colouring matter and a small quantity of water behind. In some cases these
colouring matters and other bodies contain gallic compounds, which may be recovered if
deemed desirable.
This process is applicable generally for the recovery of dye or other colouring
matters and the like from tanning extracts and other vegetable extracts.
Dated this 1st day of October 1889.

page_text: COMPLETE SPECIFICATION.
Processes for Preserving and Removing or Recovering the Colouring
Matters from Tanning and other Vegetable Extracts.
We, BENJAMIN NICHOLSON of The Torrs South Norwood in the County of Surrey
Gentleman and THOMAS PALMER B. Sc. of 85 Wool Exchange in the City of London,
Analytical and Consulting Chemist 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 :-
The object of this invention is to effect the discolorization and preservation of
tanning and other extracts chiefly of vegetable origin without the loss of tannin and
other gums and resins which are advantageous during the process of tanning.
According to this invention we provide means for the more perfect preservation of
the tannin and gum resins contained in such extracts and whereby destructive
growths such as moulds mildews and fermentation are prevented. All vegetable
extracts possess a greater or less amount of useless objectionable coloring matter
while. they also contain gum resins capable of adding weight and solidity to the
leather tanned by their agency. Hemlock bark extract, for example contains a
peculiarly tenacious coloring matter of a deep red colour.
This invention enables the colouring matter to be removed without removing the
gum resins which it is desirable to retain. For the purpose of preserving the
vegetable extract from the effects of incipient decomposition we employ the means
described in the Specification to Letters Patent granted to Collin, Benoist, Nicholson,
and Palmer bearing date 17 November 1887 No. 15766. For the treatment of
gums and resinous bodies that are more closely allied to the starch and sugar series
as in the case of fruits leaves and the like we add to the liquor obtained therefrom,
hydrogen dioxide in the proportion of about 0-07 grammes per 1000 grammes of
the extract, or 10 grammes of a product hereinafter described to 1000 grammes of
the extract, or instead, thereof there may he added such bodies or materials as
naphthol chiefly that known as beta naphthol, cresotinic acid and the like.
We will now describe a method which we have found effectual for the removal
of the obnoxious coloring matter from the extract obtained from hemlock bark.
We prefer to treat the extract prior to concentration but if desired it may be treated
afterwards, it being equally applicable in either case, and therefore we do not restrict
ourselves to any special period at which our process may be carried on or to any
exact degree of density of the extract, but we wish it to be understood that the
extract or liquor should be of such a density as to permit of a current of air being
passed through it in the vessel in which it is treated.
To the liquor while at a temperature of about 60° Fah. we add about 1% by
weight of powdered bark of Cayota (an exotic tree a native of Mexico) and about
0.25 grammes of bin-iodide of mercury, (brought into solution by any suitable
solvent thereof) to 1000 grammes of the liquor at a density of 40° Barktrometre, but
the proportions of bin-iodide of mercury will vary according to the nature of the
material under treatment.
The mixture with the Cayota being slow in its action we prefer to add thereto
2% of a prepared oil of turpentine possessing a high affinity for oxygen, or in place
thereof we may use an equivalent in the form of crude oil of turpentine, the quantity
depending on the quality and nature of the turpentine as well as on its affinity for
oxygen and as this differs very considerably no absolute rule can be given to cover
the whole series comprising the terpenes.
In place of Cayota or in conjunction with the above materials (Cayota and turpen-
tine) we may use certain bodies such for example as sea water, milk, egg albuinen,
blood serum, solution of borax, and the like also herring brine and some of the
amides which possess an affinity for the camphoraceous and other substances produced
during the oxidation of the turpentine, thereby causing it to become more readily

page_text: oxidized and largely increase its gravity not only by reason of its absorption of
oxygen but also by reason of the amount of coloring matters which it has absorbed.
The liquor drawn from the exhausters in which the bark extract is obtained is
strained in the usual, manner at a tomperature sufficiently high to preserve the gums
and other resinous bodies which would otherwise be left on the filter.
1
The liquor hot from the exhausters is runrinto vessels,,or tanks.constituting
oxidizers fitted with taps by which the liquor may be run off when required.. The
liquor may be allowed to cool in these oxidizers or it may be previously, passed
through any ordinary cooling apparatus. When the liquor is reduced to the desired
temperature, the substances herrinbefore referred to are added in the proportions
stated and the oxidizers are then closed, and a current of warm air preferably not
exceeding a temperature of 100° Fah. is forced into the liquor during a period of
from about 20 to 30 hours more or less as may be found necessary, to complete the
desired degree of discolorization.
The hereinbefore mentioned oxidizers should stand in or be surrounded by water
or other suitable heating medium raised to a temperature preferably not exceeding
140° Fah.
The oxidizers should be made of some inactive material such as lead or copper-or
preferably of earthenware. An air inlet tube is provided to each oxidizer which tube
passes into about the centre of the oxidizer and is provided at its end with a rose or
bulb distributor situated beneath the surface of the liquor contained therein.
Another tube passes from the oxidizer into a closed tank containing cold water,
and from this tank passes another tube in connection with a series of U tubes con-
taining broken coke-pumice or the like to arrest the products of oxidation conveyed
by the tube from the oxidizers and to produce an air pressure within such vessels.
At the lower bend of each U tube a space is left in which the products of oxidation
collect and which may be withdrawn by means of cocks or valves provided for the
purpose. We do not restrict ourselves to this arrangement for arresting the products
of oxidation as other well known or suitable means may be employed for the purpose.
The liquor remaining in the oxidizers will not appear to have altered much with
the exception that its density will have increased and as this is of considerable
disadvantage in effecting the removal of the colour therefrom, it is discharged into
suitable tanks or vessels where it is mixed with a further quantity of water and after
heating the liquor to about 180° Fah. it is filtered at this temperature through a wet
filter which has the effect of removing the heavy oxidized oil and with it a portion of
the coloring matter.
The oil of turpentine may be recovered by mixing with the liquor a quantity of a
suitable solvent, such as ether, light turpentine, light petroleum, benzoline, or the
like which will distil off at a temperature up to about 120° Fah. After the mixture
is allowed to stand for a time a distinct separation takes place between the oils of
turpentine and the liquor owing to the difference in gravity and may each be run off
separately.
The oil of turpentine constituting the light portion separated may be washed with
water and again separated, the washings which will contain small quantities of the oil
being added to the extract liquor and with it passed to the vacuum pans for final
concentration.
The ethereal or light portions remaining in the separators may be distilled off in a
retort thereby obtaining a clear light spirit which condenses rapidly and which may
be used again for the recovery of oil. A heavy colloidal body remains in the retort
which consists of an oxidized oily body containing a large amount of camphoric
peroxide and other powerful antiseptics, also a certain amount of the removed
colouring matter.
This body may be thinned by the addition of turpentine and re-used, or it may be
washed by hot water or steam and the resulting product used either as a soap ingre-
dient, or as an antiseptic or for mixing with varnishes.
In order to further discolorize the tanning liquor there may be added thereto a

page_text: solution of potassium alum in the proportion of say about 1 part by weight of alum
in solution to each 1000 parts by weight of the liquor the whole being then heated to
a temperature equal to that at which the original liquor had been heated in the
process of exhaustion and maintained at this heat during the process of filtration.
By this means the whole or greater portion of the gum resins are rendered capable of
passing through the filter.
The process herein before described is not suitable for treating certain extracts,
chestnut as for example, the chief characteristic of which extracts is the production
of a dark colouring matter passing from a deep olive green to black, caused through
an absorption of oxygen, and which takes place simultaneously with the decom-
position or loss of tannin whether caused by external influences or during the process
of tanning.
In treating these barks we prefer to effect a rapid extraction of their properties for
which purpose we may employ a hydro extractor, and run the liquor extracted
therefrom by suitable conduits into a churn or agitator in which it is subjected to a
violent agitation at a low temperature with petroleum ether which we prefer to be
of a light form such as will distil below 200° Fahr. After agitation the liquor is
run off into separators from which after standing for some time the liquid portion
may be run off leaving the lighter portion which may be washed in the separator
and the washings be mixed with the original extract.
The light or spirituous portion may be then distilled off in a retort and petroleum
ether recovered by any suitable means.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. Treating tanning or other vegetable extracts for the purposes of removing or
recovering the colouring matters by adding thereto an oily body of the cam-
phoraceous or turpene series such as Cayota "or turpentine or both and subjecting
the mixture to the action of a current of air in the presence of water.
*
2. Treating tanning or other vegetable extracts for the purpose of preserving the
same and removing or recovering the colouring matters by adding thereto an oily
body of the camphoraceous or turpene series such as "Cayota" or turpentine or both
and a solution of bin-iodide of mercury (or the other materials hereinbefore specified)
and subjecting the mixture to the action of a current of air in the presence of
water.
3. In combination with the subject matter of either of the preceding claiming
clauses of either of the substances herein before mentioned and subsequent treatment
for the recovery of oil or oily bodies and coloring matters all substantially as herein-
before explained.
Dated this 1st day of August 1890
J. H. JOHNSON & Co.,
Agents.