Improvements in the Preparation of Extracts of Tannin.
Year: 1898

page_text: Date of Application, 1st Feb., 1898
Complete Specification Left, 1st Nov., 1898-Accepted, 14th Jan.,
1899
Improvements in the Preparation of Extracts of Tannin.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents, 45,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature of
this invention to be as follows:-
In the Specification of a former Patent No. 8582 of 23rd April 1896 I have described
in addition to certain compounds of extracts of yellow wood and fustic wood soluble
with difficulty, which formn at temperatures of upwards of 100 deg. Centigrade with
bi-sulphites, the method of production, or preparation, of readily soluble extracts of
tannin, from ordinary extracts of quebracho, hemlock, and pine-wood.
As pointed out in said specification, those readily soluble extracts are pre-eminently
adapted for use in the various quick tanning processes.
The enhanced solubility of the extracts which we prepare in accordance with the
above mentioned former specification is owing to the fact that the insoluble non-
tannic substances undergo a somewhat peculiar change under the action of the
bi-sulphites, whether because the bi-sulphites, as such, simply exercise a dissolving
action, or because the base-whilst part of the sulphurous acid escapes-forms soluble
The surplus of
salts with the non-soluble compounds of the tannin extracts.
sulphurous acid, such as is always present, prevents oxidation and indeed causes
decoloration.
Now I have found that besides the bi-sulphites, sulphites and hydro-sulphites of
alkalies, specified in the aforesaid specification, the bi-sulphites and the like of
magnesium, calcium, zinc and alumina -if at all soluble themselves-are serviceable
for the manufacture of soluble tannin extracts from quebracho hemlock and pine
extracts.
And I have also found that soluble extracts are likewise obtained if, for the whole
or part of the bi-sulphites, sulphites and hydro-sulphites of the alkalies, there be
substituted soluble compounds giving alkaline reactions, such as borax, soda, potash,
phosphate of sodium, bi-carbonate of sodium, sodium-acetate, sodium sulphide soda
İye or ammonia.
It is in all cases necessary to add these compounds having an alkaline reaction, at a
high temperature, or else to heat the mixture; but the process may be completed in
far less time by employing far smaller quantities of the compounds referred to, than
of the sodium-sulphites. And it is always advisable to conduct operations with the
addition from time to time of reducing agents such as bi-sulphites, sulphites or
sulphides of the alkalies; but this is not absolutely necessary.
By such means soluble extracts may be obtained, without the necessity of
diluting them with bi-sulphites in as large proportions as was stated, in the said
nior specification

page_text: BAGAI DES
(a) 100 kilogrammes of quebracho extract at 26° Baumé is heated with 130 kilo-
grammes of bi-sulphite of magnesium at 20° Baumé, to a temperature of 100 deg.
Centigrade, the mixture being stirred the while, until a sample taken out will dissolve
in cold water into a sufficiently clear solution.
(b) 100 kilogrammes of quebracho extract at 26° Bé. is heated to a temperature of
from 90 to 95 deg. Centigrade then 76 kilogrammes of aminonia diluted with the
same amount of water is slowly added, with or without the super-addition of sulphites,
and the whole is heated until a sample taken out of the mixture makes an almost
clear solution in cold water.
(c) In a doubled-walled stirring apparatus 1050 kilogrammes of quebracho extract
is treated with 70 kilogrammes of soda solution at 12 Bé. and 18 kilogrammes of
sodium bi-sulphite at 30 Bé.
(d) 1000 kilogrammes of quebracho extract at 26° Bé. is heated in a spacious
vessel or chamber fitted with stirring mechanism, to about 95 deg. Centigrade; and
into this heated extract is allowed to flow slowly a lot solution of 80 kilogrammes of
soda crystals dissolved in 100 litres of water, with or without the addition of
bi-sulphites or of a small amount of sodium sulphide. Both the admission of the
soda solution and the temperature are so regulated as to avoid an overflow of froth;
and the mixture is finally heated, the same as in the other cases, until the desired
degree of solubility is attained.
The proportions, temperature and time may fluctuate within wide limits; besides,
the additions above referred to, having an alkaline reaction, may be replaced by
equivalent quantities of similarly acting substances. The same remarks apply to the
treatment of hemlock and pine extracts.
Furthermore the wood and bark of the quebracho tree and hemlock-pine may be
subjected to an extracting process with water having a slight alkaline reaction, when
soluble tannin extracts will form out of the materials named.
Improvements in the Preparation of Extracts of Tannin.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, 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:-
In the Specification of a former Patent No. 8582 of 23rd April 1896 I have
described, in addition to certain compounds of extracts of yellow wood and fustic
wood soluble with difficulty, which are formed at temperatures of upwards of 100 deg.
Centigrade with bi-sulphites,-the method of production or preparation, of readily
soluble extracts of tannin, from ordinary extracts of quebracho hemlock and pine-wood.
As pointed out in said Specification, those readily soluble extracts are pre-eminently
adapted for use in the various quick tanning processes.
The enhanced solubility of the extracts which we prepare in accordance with the
above-mentioned former Specification is owing to the fact that the insoluble non-
tannic substances undergo a somewhat peculiar change under the action of the
bi-sulphites; whether because the bi-sulphites, as such, simply exercise a dissolving

page_text: action, or because the base-whilst part of the sulphurous acid escapes-forms soluble
salts with the non-soluble compounds of the tannin extracts. The surplus of sulphurous
acid, such as is always present, prevents oxidation and indeed causes decoloration.
Now I have found that besides the bi-sulphites, sulphites and hydro-sulphites of
alkalies, specified in the aforesaid Specification, the bi-sulphites and the like of
magnesium, calcium, zinc and alumina-if at all soluble themselves-are serviceable
for the manufacture of soluble tannin extracts from quebracho hemlock and pine
extracts.
And I have also found that soluble extracts are likewise obtained if, for the
whole or part of the bi-sulphites, sulphites and hydro-sulphites of the alkalies,
there be substituted soluble compounds giving alkaline reactions, such as borax,
soda, potash, phosphate of sodium, bi-carbonate of sodium sodium-acetate, sodium
sulphide, soda lye or ammonia.
It is in all cases necessary to add these compounds, having an alkaline reaction,
at a high temperature, or else to heat the mixture; but the process may be
completed in far less time, by employing far smaller quantities of the compounds
referred to, than of the sodium-sulphites. And it is always advisable to conduct
operations with the addition from time to time of reducing agents such as
bi-sulphites, sulphites or sulphides of the alkalies; but this is not absolutely
necessary.
By such means soluble extracts may be obtained, without the necessity of
diluting them with bi-sulphites in as large proportions as was stated in the said
prior Sinanifination
(a) 100 kilogrammes of quebracho-extract at 26° Beaumé is heated, with
130 kilogrammes of bi-sulphite of magnesium at 20° Beaumné, to a temperature of
100 deg. Centigrade, the mixture being stirred the while, until a sample taken out
will dissolve in cold water into a sufficiently clear solution.
(b) 100 kilogrammes of quebracho extract at 26° Bé., is heated to a temperature
of from 90 to 95 deg. Centigrade; then 76 kilogrammes of aninonia diluted with
the same amount of water is slowly added, with or without the super-addition
of sulphites, and the whole is heated until a sample taken out of the mixture makes
an almost clear solution in cold water.
(c) In double walled stirring apparatus 1000 kilogramines of quebracho extract is
treated with 70 kilogrammes of soda solution at 12° Bé. and 18 kilogrammes of
sodium bi-sulphite at 30° Bé.
(d) 1000 kilogrammes of quebracho extract at 26° Bé. is heated in a spacious vessel
or chamber fitted with stirring mechanism, to about 95 deg. Centigrade; and into
this heated extract is allowed to flow slowly, a hot solution of 80 kilogrammes of
crystals of sodic carbonate dissolved in 100 litres of water, with or without the
addition of bi-sulphites or of a small amount of sodium sulphide. Both the ad-
mission of the soda solution and the temperature are so regulated as to avoid an
overflow of froth; and the mixture is finally heated, the same as in the other cases,
until the desired degree of solubility is attained.
The preparations, temperature and time may fluctuate within wide limits, besides,
the additions above referred to, having an alkaline reaction, may be replaced by equi-
valent quantities of similarly acting substances. The same remarks apply to the
treatment of hemlock and pine extract.
Furthermore the wood and bark of the quebracho tree and hemlock-pine may be
subjected to an extracting process with water having a slight alkaline reaction, when
soluble tannin extracts will form out of the materials named. In such cases it is
always necessary to add a certain quantity of reducing substances as sulphites,
hydrosulphites, sulphides as already mentioned, zinc or inagnesium dust, or formates,
in order to prevent as much as possible any oxidation, as otherwise the tannin ex-
tracts would be too coloured and not suitable for use.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, as communicated
to me by my foreign correspondents, I declare that what I clain is:-
1. The preparation of readily soluble quebracho extracts from ordinary quebracho,
hemlock and pine-extracts, or if preferred from quebracho wood or the bark of hem-
lock and pine, by treating them with substances (or compounds) having an alkaline
reaction, with or without the addition of sulphites or hydro-sulphites, sulphides,
formates, zinc or magnesium dust, in a word of reducing substances, at a high
temperature.
2. The preparation of tannin extracts by the treatment of quebracho, hemlock or
pine-extract in the heat," with bi-sulphites and hydro-sulphites of the alkaline
earths zinc and aluminium.
3. The employment of the products or preparations obtained in accordance with
the Claime 1 and 2 for tanning purposen,
Dated this
1st day of November 1836.
"
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
OCOL
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