A NEW PROCESS OF TANNING
Year: 1861

page_text: LETTERS PATENT to Louis Francois Duval and Louis Andre Beaudet,
at Paris, 33, Bard. St. Martin, Town in the French Empire, for the
Invention of "A NEW PROCESS OF TANNING."
PROVISIONAL SPECIFICATION left by the said Louis Francois Duval and
Louis Andre Beaudet, at the Office of the Commissioners of Patents, with
their Petition, on the 12th November 1861.
We, LOUIS FRANCOIS DUVAL, and. LOUIS ANDRE BEAUDET, at Paris, 33,
Bard. St. Martin, Town in the French Empire, do hereby declare the nature
of our said Invention for "A NEW PROCESS OF TANNING," to be as follows:-
In this Specification, to avoid repetition, we use the word "skins" as
meaning both skins and hides, and we designate the pit, trough, chamber, or
vessel in which, the tanning is performed the "pit or vessel."
We prepare solutions of tannin preserved from all contact with air or
oxygen, and particularly under the sole influence of neutral gases having
neither alkaline nor acid properties, and exerting no prejudicial action on the
tannin or on the skins. We. prefer to employ (either under pressure or not)
hydrogen gas or gaseous. compounds thereof, or azote or nitrogen, either
together or separately. We perform the tanning in pits or vessels closed
hermetically and deprived of air in the presence or by means of neutral
gases. We particularly recommend for the purpose the use of hydrogen in
¡Price Sd.1

page_text: such pits or vessels, whereby we preserve the skins, decolorize men, or impart
a fine marketable color and perform the tanning more expeditiously. We
arrange and connect tanning pits or vessels in the manner of the arrangement
known as Woulfe's apparatus. We tan by means of solutions of tannin
which we produce and employ in closed vessels or chambers under the
influence and in the presence of hydrogen gas, or gaseous compounds thereof,
or of azote or nitrogen gas, or of some other neutral gas having no acid nor
alkaline property, and exerting no injurious effect on the tannin or on the
skins.
We tan by inclosing the skins with tanning liquids, preferably prepared as
described in pits or vessels hermetically closed so as to prevent access of or
contact with atmospheric air and escape of gases.
We admit into such pits or vessels and pass through the tanning liquids
contained therein a stream of hydrogen gas, or a gaseous compound thereof,
or of azote or nitrogen gas, or other neutral gas free from acid or alkaline
properties, and exerting no prejudicial action on the tannin and skins, and by
means thereof we drive out the atmospheric air and the noxious gases.
We construct apparatus for the purpose, consisting of a series of pits or
vessels communicating with each other in the manner of a Woulfe's apparatus.
Thus a number of vessels or chambers containing the tannin may be arranged
in a row and communicate by means of pipes with each other, and also with a
gas supply and purifier at one end of the series and with a gas receiver or
holder (preferably a water tank) at the other. The pipes are arranged as in
the Woulfe's apparatus, and the gas is sent through the pipes so as to pass
through the tannin from the first to the last vessel or chamber of the series,
and thence into the gas holder. The tanning pits or vessels are arranged
and communicate in like manner; this series also having a gas supply at one
end and a gas holder at the other. The pits or vessels contain the skins and
tanning liquids, and are covered over by air and gas tight covers
(from hooks, on the under side of which the skins are preferably suspended).
The gas is sent through the whole series consecutively by means of the pipes,
passes through the tanning liquid so as to expel the air, and finally escapes
into a gas holder, in which it may be stored to be used over again. There
may be a series communicating in like manner in which the gas in passing
from the holder into the tanning pits or vessels is subjected to the action of a
pump to raise the pressure to the required point.
Instead of having to transfer the skins from pit to pit we gradually raise
the density of the tanning liquors as their strength becomes expended by
means of more highly concentrated tanning extracts; for this purpose the

page_text: extracting apparatus that contains the tannin solution is brought into com-
munication with the pits or vessels by a syphon. The gas may be employed
under pressure or not; it may be evolved in a strong trough and a pump used
to raise the pressure as required.
The tannin and the skins being preserved from contact with the atmospheric
air are kept from injury or deterioration. Bark is preserved from contact
with the air contained in the water, so that oxygen cannot exert its injurious
effects. We prevent fermentation and the formation or evolution of gallic
and carbonic acids. By employing gases that deprive tannin and skins of the
oxygen the tanning process is accelerated. We also resist the production of
carbonic acid gas, which, by combining with the lime retained in the skins
after unhairing, exerts prejudicial effects.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Louis Francois Duval and Louis Andre Beaudet, in the Great
Seal Patent Office on the 12th May 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, LOUIS
FRANCOIS DUVAL and LOUIS ANDRE BEAUDET, at Paris, 33, Bard. St. Martin,
Town in the French Empire, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of November, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us,
the said Louis Francois Duval and Louis Andre Beaudet, Her special licence
that we, the said Louis Francois Duval and Louis Andre Beaudet, our
executors, administrators, and assigns, or such others as we, the said Louis
Francois Duval and Louis Andre Beaudet, our executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "A NEW PROCESS OF TANNING," upon the condition (amongst
others) that we, the said .Louis Francois Duval and Louis Andre Beaudet,
our executors or administrators, by an instrument in writing under our or
their hands and seals, or under the hand and seal of one of us or them
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to

page_text: be filed in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that we, the said Louis Francois Duval and Louis
Andre Beaudet, do hereby declare the nature of the said Invention, and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement thereof, reference being had
to the accompanying Drawings and to the letters and figures marked thereon,
that is to say :-
In this Specification, to avoid repetition, we designate the pit, trough,
chamber, or vessel in which the tannin is performed by the expression "pit
or vessel."
According to our Invention we prepare solutions of tannin or tanning liquors
in close vessels, chambers, or receivers, in such manner that during the prepa-
ration of such solutions they shall be kept from all contact with atmospheric
air or with oxygen, or in other words, atmospheric air and oxygen shall be
excluded from them; and we prepare them in the presence and under the sole
action of neutral gases having no alkaline nor acid properties, and being of a
ature to exert no prejudicial action on the tannin or on the hides or skins.
The gas we prefer to employ for the purpose is hydrogen gas, or gaseous com-
pounds thereof, or azote or nitrogen gas, or hydrogen or its compounds with
azote or nitrogen, and we employ such gas or gases either under pressure or
not.
According to our Invention, also, we perform the process of tanning in pits,
troughs, chambers, or vessels closed hermetically, from which the atmospheric
air is excluded, so that while the tanning operation is being performed therein
the hides or skins shall be kept wholly free from the presence of or contact
with the atmospheric air; and we admit into the. pits or vessels hydrogen gas,
or gaseous compounds thereof, or azote, or nitrogen gas, or some other neutral
gas having no acid nor alkaline property, and being of a nature to exert no
injurious effect either on the tannin or on the hides or skins, so that we perform
the tanning operation in the presence and under the action of such gas or
gases.
We particularly recommend for the purposes of our Invention the use of
hydrogen gas, as that agent especially preserves the skins, decolorizes them, r
imparts to them a fine marketable color, and allows of the tanning being per-
formed more expeditiously.
C
We also arrange or connect tanning pits or vessels after the manner of the
arrangement known as Woulfe's apparatus, whereby we effect communication
between the said pits or vessels. We usually prefer to proceed as follows:-

page_text: We admit into the vessels in which the tanning solutions or liquids are to be
prepared hydrogen or other neutral gas of the nature above stated, taking care
to exclude atmospheric air from the interior of the vessels, which are closed
hermetically, so as to be air and gas-tight; and having prepared the tanning
liquids or solutions preferably in the manner herein-before described, we
enclose the hides or skins to be tanned, together with the said tanning liquids
or solutions, in pits or vessels hermetically closed, so as to prevent the escape
of gases therefrom, and to prevent atmospheric air having access to or coming
in contact with the contents of the pits or vessels. We then admit into such
pits or vessels and pass through the tanning liquids contained therein a current
of hydrogen gas, or a gaseous compound thereof, or nitrogen, or other neutral
gas of the nature above stated, whereby we expel the atmospheric air and
noxious gases. The apparatus we prefer to use for the purpose of preparing
the solutions or liquors, and also for that of performing the tanning, consists
of a series of vessels communicating with each other in the manner of a
Woulfe's apparatus, as represented in the accompanying Drawings, which
show apparatus suitable for performing our Invention, consisting of a number
of vessels or chambers arranged in a row, and communicating with each other
by means of pipes, and also communicating at one end of the series with a
vessel whence the gas is supplied, and with a purifier, and at the other end of
the series with a gas receiver or holder, which is preferably a tank, holding
water. The pipes are arranged as in the Woulfe's apparatus, and the gas is
sent through the pipes so as to pass all through the series of vessels from the
first to the last thereof, and theirce into a gas holder.
Figure represents a series of such vessels for preparing the tanning solu-
tions, the vessels A containing the tanning materials through which the gas is
passed; Figure 2 represents a series for performing the tanning, the vessels B
containing the hides or skins and the tanning solutions; C is the gas supply;
D, the purifier; E, the communicating pipes. The vessels are closed by covers G.
rendered air and gas-tight; the hides or skins are preferably suspended from
hooks on the under side of the covers G, (Figure 2.) The gas having been
sent through the series of vessels B expels the air therefrom, and escapes into
a gas holder, in which it may be stored to be used over again. The gas to be
used may be first evolved in a strong trough, and if used under pressure; a
pump may be employed to raise the pressure as required. Figure 3 shews the
first of a series of vessels which communicate in similar manner to Figure 2,
but in which the gas in passing from the holder into the vessels is subjected to
the action of a pump I, which raises the pressure to the required point. The
Figures are all vertical elevations, chiefly in section.

page_text: Instead of having to transfer the skins from pit to pit, as in the methods
hitherto adopted, we gradually raise the density of the tanning liquors in the
vessels as their strength becomes impaired, by admitting into the vessels more
highly concentrated tanning extracts; for this purpose the extracting appa-
ratus that contains the tannin solutions may be brought into communication
with the tanning pits or vessels by a syphon.
By our Invention the tannin and the skins being preserved from contact
with atmospheric air are kept from injury or deterioration, and no acid or
putrid fermentation can ensue. The bark being preserved from contact with
the air contained in the water, oxygen cannot exert its injurious effects.
We prevent fermentation and the formation or evolution of gallic and car-
bonic acids, and by employing gases that keep the tannin and hides or skins
free from oxygen, the tanning is accelerated. We especially resist the pro-
duction of carbonic acid gas, which, by combining with the lime contained in
the hides or skins after unhairing, exerts prejudicial effects.
By means of our Invention we are enabled to dispense with the pre-
liminary operations of handling, and other preliminary processes that usually
precede the deposit of skins or hides in the tanning pits or vessels. The tan
pits or vats at present in use may be adapted for the purposes of our Invention
by fitting them with covers and pipes occording to the plan herein described.
We recommend that the hooks fixed to the covers for suspending the hides or
skins should be of copper. Of course any number of pits or vessels may be
used for performing our Invention, according to the quantity of material under
treatment. We may add that nascent hydrogen acts as a decolorizing agent,
so that skins and hides tanned by our processes acquire a beautiful appearance.
Hydrogen gas is light and elastic, and when compressed penetrates into the
pores of the skin and swells it without injuring it. The gases used in carrying
our Invention into effect may be prepared and purified in any ordinary well
known manner. By preserving the bark from contact with air contained in
the water, oxygen cannot exert its prejudicial effects on the organic vege-
table matter, the tannic acid alone acting on the hide or skin. In the ordinary
mode of tanning hitherto practised fermentation always ensues, the skins
become injured, the tannin deteriorated, and gallic and carbonic acid formed,
so that the skins have to be kept longer in the tanning pits, and a large
expenditure of bark is required, the skin even undergoing fermentation from
the oxygen of the water, and putrid fermentation setting in, which the tannin
however large the quantity employed, cannot prevent; whereas by our
Invention, we prevent fermentation, the formation of acids, and the action of
any alkali which would convert the tannin into gallic acid; for there being no

page_text: oxygen present, tanning, when performed under the action and in the presence
of any of the gases above mentioned, only is effective; any gas that will
deprive the tannin and the skins of the oxygen contained therein therefore
shortens the duration of the tanning operation. Among the injurious effects
of carbonic acid gas in tanning we may mention. that when skins and hides
have been unhaired by lime there always remains in them, notwithstanding
the washings they undergo, a quantity of lime, with which the carbonic acid
combines, and which it converts into an insoluble carbonate that remains in
the leather, and renders it liable to crack or break; similar effects ensue when
the water becomes, charged with certain salts, such as sulphate of lime,
chloride of calcium, and others. Moreover, carbonic acid instantaneously pre-
cipitates the tannin to the bottom of the pit, as may be tested by enclosing a
solution of concentrated tannin in a vessel containing carbonic acid gas, in
which the tannin will be found precipitated in a state of resin. Gallic acid
also has the bad effect of reducing the density of the tannin, dissolving the gela-
tine, and causing an unfavorable expansion of the pores; all acids, even the
weakest, precipitate tannin, render it insoluble in water, dissolve gelatine; and
occasion a loss in weight.
We wish it to be understood that we do not restrict ourselves to the
arrangement of apparatus described, nor to the precise details herein set forth
for performing our Invention, as the same may be varied without departing
from the nature of the Invention as herein set forth.
We prefer to prepare the tanning solutions or liquors, as herein set forth,
but do not restrict ourselves thereto, as we can tan, according to our process,
with tanning liquids otherwise prepared.
Having now described the nature of our said Invention, and in what manner
the same may be performed, we declare that we .claim,―
First, the preparing of solutions of tannin or tanning liquors in such manner.
that while being prepared they are kept from all contact with atmospheric air
or with oxygen, and we especially claim the so preparing them, and in addition
thereto subjecting them to the action of neutral gases, having neither alkaline
nor acid properties, and exerting no prejudicial action on the tannin or on
the hides and skins, preferring to use for such purpose, under pressure or
otherwise, hydrogen gas or its gaseous compounds, or azote or nitrogen gas, or
both hydrogen and azote.
Second, we claim the tanning of hides and skins in hermetically closed pits
or vessels, from which atmospheric air is excluded, but into which pits or
vessels is or are admitted under pressure or otherwise a neutral gas or gases
(having neither alkaline nor acid properties, and exerting no prejudicial effect

page_text: on the tannin or on the hides or skins), so that the tanning is performed in
the presence and under the action of such gas or gases.
Third, we claim the employment of hydrogen in hermetically closed pits or
vessels, in the manner and by the means herein-before described, or in a
manner and by means similar thereto for the purposes above set forth.
Fourth, we claim the application or combination of the arrangement, known
as Woulfe's apparatus, to or with tanning pits or vessels for the purpose of
bringing them into, communication with each other, as herein-before described.
Fifth, we claim the combination of means constituting our improved process
of tanning, herein-before described.
In witness whereof, we, the said Louis Francois Duval and Louis Andre
Beaudet, have hereunto set our hands and seals, this Eighth day of
May, in the year of our Lord One thousand eight hundred and
sixty-two.
Witness,
EMILE BARRAULT,
33, Bard. St. Martin.
L. A. BEAUDET. (L.S.)
(L.S.)
L. DUVAL.