Improved Process and Apparatus for the Rapid Tanning of Skins and Hides.
Year: 1897

page_text: Date of Application, 15th July, 1897
Complete Specification Left, 14th Apr., 1898-Accepted, 18th June, 1898
PROVISIONAL SPECIFICATION.
Improved Process and Apparatus for the Rapid Tanning of Skins
and Hides.
I, CHARTEN MICHEL, of 14, Rue Lepic, Paris, in the Republic of France, Manu-
facturer, do hereby declare the nature of this invention to be as follows:-
This invention relates to a novel apparatus enabling the tanning of skins and
hides to be performed both rapidly and methodically; and it also relates to the
composition of the tanning bath, which will be found particularly advantageous
in connection with the present improved apparatus, though its employment is not
confined to this particular method of applying it; and conversely, the apparatus is
not specially confined to the case herein described, where it is operated in conjunc-
tion with the improved tanning bath.
"
Hitherto, the rapid tanning of skins has generally been conducted by means of
a rotary drum" or cylinder, the inner surface of which was furnished with pins
or pegs, and which contained a certain amount of tannic solutions or suitable tan-
ning compounds, wherein the hides or skins are immersed.
Skins and hides, to be properly tanned and converted into leather of real market-
able value, must absorb a predetermined quantity of tannin, and to this end, it
is necessary that the absorption should take place in a gradual and continuous
manner, as it does in the usual tan-pits.
In the course of most of the quick tanning processes hitherto devised, it is found
necessary to enrich the tannic solutions with a quantity of tannin approximately
equal to that which is supposed to have, by then, been absorbed, but the attendant
hardly ever exactly knows when and in what proportions such addition should be
made.
Besides, in order to add tannin, it is necessary to stop the machine, to open
various orifices provided in the cylinder, and then admit the concentrated extracts
of tannin, in such quantities as may be desirable.
But in thus stopping the cylinder and opening its orifices; cold air is allowed to
enter it, while the temperature prevailing in such cylinder at the time is generally
somewhere about + 250 Centigrade. The solutions, accordingly, cool, and in cool-
ing, become oxidised, with the result that they cease to penetrate the pores of the
skins or hides at the very period which otherwise would have been most favourable
to such penetration. In those arrangements where the tanning solution is intro-
duced into the cylinder through the trunnions of the cylinder, the same uncertainty
prevails in regard to the quantity of liquid to be admitted.
The present apparatus enables the richness of the tannic "juice" or solution
to be at any time during the operation accurately ascertained, and any desired
quantity of concentrated extracts to be admitted automatically, whenever it is
deemed desirable to restore its normal richness or state of concentration to the
tannin mixture without interrupting operations or opening the cylinder.

page_text: In carrying my invention into practice the apparatus, which it is proposed to
describe as a moveable automatic tan-pit" mainly consists of a cylindrical cham-
ber adapted to revolve on two trunnions or journals. The inner wall of the
cylinder is studded with series of pegs, termed "mushrooms." It will be under-
stood as a matter of fact, that this appellation is justified by their shape, which
differentiates them from the plain pegs or pins hitherto used.
The cylinder is provided with doors of which there may be any sufficient number
and which may be formed in any suitable manner; they being intended to admit
the skins to be treated into the cylindrical chamber.
On one side, or at one end, of the cylindrical chamber, a double bottom is pro-
vided, which communicates with the interior of the apparatus through suitable
apertureş.
Within this double bottom there is fitted a serpentine-shaped tube, open at one
end, or instead of being open it might be merely perforated. The other end of
this tube passes through the cylinder trunnion, situated on that side, thus forming
a concentric spindle which is loose in its relation to the said trunnion. This
tubular spindle and also, therefore, the serpentine tube proper are adapted to
receive rotary motion independently of the motion of the cylinder. The tubular
spindle has a small pulley attached to it, which a strap connects with another
pulley mounted upon a shaft which receives motion from the trunnion through the
medium of two conveniently arranged pullies.
Other means for transmitting motion might however be adopted, if preferred,
such as toothed gearing or the like.
By altering the relation of these pulleys, or tooth wheels, as the case may be,
the speed of the serpentine tube may be varied and adjusted at will in relation to
that of the cylinder.
The tubular spindle may terminate at its outer end in a test glass, the lower part
of which is connected by means of a tube with the cylinder or drum at the oppo-
site trunnion. Owing to this arrangement, a continuous current of the liquor
contained in the cylindrical chamber circulates through the test tube, wherein may
be located a tannometer or a densimeter, enabling the richness of the tanning
solution to be at any time ascertained.
Outside the cylinder and around its periphery are provided any suitable number
of "reservoirs," which are to contain the concentrated extract of tannin intended
to keep up the requisite degree of concentration or richness of the tannic liquor,
whilst the apparatus is at work. They communicate with the interior of the
cylinder through openings provided with valves which are held down upon their
seats by springs. The valve-rods project outside the said reservoirs. Each of the
rods whilst the cylinder is rotating, engages with a stationary cam, whereby they
are depressed, so that the corresponding valve opens and allows a certain amount
of the liquor contained in the reservoirs to flow into the interior of the cylinder.
Thus each reservoir in turn is made to feed the cylinder, and it will be under-
stood that the number of such reservoirs may vary to suit any requirements.
By such an arangement, therefore, the richness of the tannic juice in operation
may be maintained at a constant degree without any necessity for the cylinder to
be opened and placed in communication with the atmosphere. And as a tanno-
meter is provided within the test tube, the quality of the tanning liquor may at
any time be tested and the amount of liquor flowing from the reservoirs into the
drum controlled accordingly.
The cam piece which the ends of the rods strike against as they move past is
adapted to oscillate on a pivot; and it is operated by a lever arrangement. By
varying the position of this cam, the rods when they meet it, are caused to move
inwardly for a greater or less distance and, accordingly, allow greater or less quan-
tities of liquor at a time to pass out. Eventually, when it reaches a certain
position, the cam is placed out of contact with the rods, when the discharge of
liquid stops.
Thus, by watching the readings of the tannometer, the tanning liquid may be

page_text: in a perfectly reliable manner maintained at the requisite degree of richness, and
as small additions of concentrated extracts may be made, as may be desired, whilst
keeping the cylinder all the time hermetically closed, and without even a momen-
tary interruption of the work. Inwardly the cylindrical chamber is fitted with
mushrooms," the object of which is to alternately raise the hides in the course
of rotation and to allow them to drop into the liquid. It will be understood that
the mushroom shape given to these pieces, which are substitutes for the usual
pegs, is far more favourable to the successful completion of the process than the
peg shape; for they are intended to raise the hides in the apparatus as high as
possible and let them drop into the liquid again abruptly, so as to impart to them
a somewhat violent shock as they sink back into the liquor, thereby assisting the
penetration of the juice. The cylinder is provided with taps suitable for emptying
the same.
Having thus given a complete description of my apparatus and its operation,
I wish it distinctly understood that it may be constructed of any size or dimensions,
and that its shape and details of construction may be modified, so long as the modi-
fications do not effect the principle of its arrangement. Thus, for example, the
rotary chamber or drum," instead of being circular, may be polygonal, and the
serpentine tube might rotate along with the drum instead of being independent of
the same.
66
It may obviously be employed in conjunction with baths of any description. I
will here however give the formular of my own compound which, in conjunction
with the apparatus described, gives excellent results; and I will also state the
method of operation which I generally employ.
In a chamber of sufficient capacity there is placed 4,000 litres of tannic juice or
solution at 4 or 5° Beaume aerometer according to the nature of the skin to bo
tanned.
500 kilogrammes of ammonia for every 100 kilogrammes of skin or hide; and
500 kilogrammes of carbonate of soda for every 100 kilogrammes of hide.
This bath is intended for use in the production of soft leather.
Where it is desired to obtain leather of greater firmness, 500 kilogrammes of
boric acid for every 100 kilogrammes of skin is substituted for the ammonia and
carbonate of soda.
From 500 to 800 kilogrammes of skins or hides are placed in the rotary chamber,
which is then set in motion at a speed of from 10 to 12 revolutions per minute.
The machine is stopped every two hours for half an hour, and before stopping
it the cylinder is made to perform one half of a revolution in the direction oppo-
site to that of its normal motion, whereby the skins are caused to redescend into
the tannic solutions, dropping from the mushrooms from which they were sus-
pended; so that all the skins contained in the cylinder are thus plunged into the
tannic juice.
The apparatus employed is preferably three metres in diameter and two metres
long, and provided with four reservoirs containing 250 kilogrammes of 20° concen-
trated extract each.
These particulars, however, as before stated, are given here only by way of
example, and the description of the method, too, is merely intended to serve as an
illustration of the practical use of the invention.
171
T
1007
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: Improved Process and Apparatus for the Rapid Tanning of Skins
and Hides.
I, CHARTEN MICHEL, of 14, Rue Lepic, Paris, in the Republic of France, Manu-
facturer, do hereby decare 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: -
This invention relates to a novel apparatus enabling the tanning of skins and
Lides to be performed both rapidly and methodically; and it also relates to the
composition of the tanning bath, which will be found particularly advantageous
in connection with the present improved apparatus, though its employment is not
confined to this particular method of applying it; and conversely, the apparatus is
not specially confined to the case herein described, where it is operated in conjunc-
tion with the improved tanning bath.
Hitherto, the rapid tanning of skins has generally been conducted by means of
a rotary "drum" or cylinder, the inner surface of which was furnished with pins
or pegs, and which contains a certain amount of tannic solutions or suitable tan-
ning compounds, wherein the hides or skins were immersed.
Skins and hides, to be properly tanned and converted into leather of real market-
able value, must absorb a predetermined quantity of tannin, and to this end, it
is necessary that the absorption should take place in a gradual and continuous
manner, as it does in the usual tan-pits.
In the course of most of the quick tanning processes hitherto devised, it is found
necessary to enrich the tannic solutions with a quantity of tannin approximately
equal to that which is supposed to have, by then, been absorbed; but the attendant
hardly ever exactly knows when and in what proportions such addition should be
made.
Besides, in order to add tannin, it is necessary to stop the machine, to open
various orifices provided in the cylinder, and then admit the concentrated extracts
of tannin, in such quantities as may be desirable.
But in thus stopping the cylinder and opening its orifices, cold air is allowed to
enter it, while the temperature prevailing in such cylinder at the time is generally
somewhere about +25° Centigrade. The solutions, accordingly, cool, and in cool-
ing, become oxidised, with the result that they cease to penetrate the pores of the
skins or hides at the very period which otherwise would have been most favourable
to such penetration. In those arrangements where the tanning solution is intro-
duced into the cylinder through the trunnions of the cylinder, the same uncertainty
prevails in regard to the quantity of liquid to be admitted.
The present apparatus enables the richness of the tannic "juice" or solution
to be at any time during the operation accurately ascertained, and any desired
quantity of concentrated extracts to be admitted automatically, whenever it is
deemed desirable to restore its normal richness or state of concentration to the
tannin mixture without interrupting operations or opening the cylinder.
In the accompanying drawing,
Figure 1 is a longitudinal section of the apparatus,
Figure 2 is an end elevation thereof partly in section,
Figure 3 is a cross section of the said apparatus, and
Figure 4 is a detail view of one of the valves for connecting the reservoirs with
the cylinder or "drum."
a movable auto-
The improved apparatus, which it is proposed to describe as
matic tan-pit" mainly consists of a cylindrical chamber A adapted to revolve on

page_text: two trunnions or journals a a. The inner wall of the cylinder is studded with
series of pegs or pins having mushroom-shaped heads B.
The cylinder is provided with doors C C, of which there may be any desired
number and which may be formed in any suitable manner; they being intended
to admit the skins to be treated into the cylindrical chamber.
On one side, or at one end, of the cylindrical chamber, a double bottom D is
provided, which communicates with the interior of the apparatus through suit-
able apertures d d
Within this double bottom there is fitted a serpentine-shaped tube E, open at
one end, at e; or instead of being open it might be merely perforated. The other
end of this tube passes through the cylinder trunnion a, situated on that side,
thus forming a concentric spindle e¹, which is loose in its relation to the said trun-
nion. This tubular spindle e¹, and also, therefore, the serpentine tube proper are
adapted to receive rotary motion independently of the motion of the cylinder. The
tubular spindle e¹, has a small pulley connected by a strap with another
pulley e, mounted upon a shaft which receives motion from the trunnion through
the medium of two conveniently arranged pullies e5 and e6.
Other means for transmitting motion might however be adopted, if preferred,
such as toothed gearing or the like.
4
By altering the relation of these pullies, or tooth wheels, as the case may be,
the speed of the serpentine tube may be varied and adjusted at will in relation to
that of the cylinder.
The tubular spindle e' may terminate at its outer end in a test glass F, the lower
part of which is connected by means of a tube f with the cylinder or drum A, at
the opposite trunnion fl. Owing to this arrangement, a continuous current of
the liquor contained in the cylindrical chamber circulates through the test tube F,
wherein may be located a tannometer or a densimeter, enabling the richness of the
tanning solution to be at any time ascertained.
Outside the cylinder and around its periphery are provided any suitable number
of "reservoirs," such as G G G G, which are to contain the concentrated extract
of tannin intended to keep up the requisite degree of concentration or richness of
the tannic liquor, whilst the apparatus is at work. They communicate with the
interior of the cylinder through openings g, provided with valves g¹, which are
held down upon their seats by springs 92 (Figure 4). The valve-rods g³ project
outside the said reservoirs and each of the said rods g³, whilst the cylinder is
rotating, engages with a stationary cam H, whereby they are depressed, so that
the corresponding valve opens and allows a certain amount of the liquor contained
in the reservoirs to flow into the interior of the cylinder.
Thus each reservoir in turn is made to feed the cylinder, and it will be under-
stood that the number of such reservoirs may be varied to suit the particular re-
quirements of each case. By the use of this arrangement, therefore, the richness
of the tannic juice in operation may be maintained at a constant degree without
the necessity of opening the cylinder and consequently admitting air therein. And
as a tannometer is provided within the test tube, the quality of the tanning liquor
may at any time be tested and the amount of liquor flowing from the reservoirs
into the drum controlled accordingly.
The admission of the liquor to the cylinder or drum is controlled as follows:
The cam piece with which the ends of the rods engage as they move past is
adapted to oscillate on a pivot, and it is operated by a lever arrangement h h¹.
By varying the position of this cam, the rods g³, when they come in contact there-
with are caused to move inwardly for a greater or less distance, and, accordingly,
allow more or less liquor to pass into the cylinder at a time. When it reaches a
certain position, the said cam will be out of contact with the rods, and the dis-
charge of liquor will cease.
Thus, by watching the readings of the tannometer, the tanning liquor may be
in a perfectly reliable manner maintained at the requisite degree of richness, and
as small additions of concentrated extracts may be made, as may be desired, whilst

page_text: keeping the cylinder all the time hermetically closed, and even without even a
momentary interruption of the work. On the inside the cylindrical chamber is
fitted with mushroom-shaped heads B, the object of which is to alternately raise
the hides in the course of rotation and to allow them to drop into the liquor. It
will be understood that the mushroom shape given to these pieces, which are sub-
stitutes for the usual pegs, if far more favourable to the successful completion of
the process than the peg shape; for they are intended to raise the hides in the
apparatus as high as possible and let them drop into the liquor again abruptly,
so as to impart to them a somewhat violent shock as they sink back into the liquor,
thereby assisting the penetration of the juice. The cylinder is provided with suit-
able taps I for emptying the same.
Having thus given a complete description of my apparatus and its operation, I
wish it distinctly understood that it may be constructed of any size or dimensions,
and that its shape and details of construction may be modified, so long as the
modifications do not effect the principle of its arrangement. Thus, for example
the rotary chamber or drum," instead of being circular, may be polygonal, and
the serpentine tube might rotate along with the drum instead of being independent
of the same.
"
It may obviously be employed in conjunction with baths of any description. I
will here however give the formulae of my own compound which, in conjunction
with the apparatus described, gives excellent results; and I will also state the
method of operation which I generally employ.
In a chamber of sufficient capacity there is placed 4,000 litres of tannic juice or
solution at 4 or 5° according to the nature of the skin to be tanned.
500 kilogrammes of ammonia for every 100 kilogrammes of skin or hide; and
500 kilogrammes of carbonate of soda for every 100 kilogrammes of hide.
This bath is intended for use in the production of soft leather.
Where it is desired to obtain leather of greater firmness, 500 kilogrammes of
boric acid for every 100 kilogrammes of skin is substituted for the ammonia and
carbonate of soda.
From 500 to 800 kilogrammes of skins or hides are placed in the rotary chamber,
which is then set in motion at a speed of from 10 to 12 revolutions per minute.
The machine is stopped every two hours for half an hour, and before stopping it
the cylinder is made to perform one half of a revolution in the direction opposite
to that of its normal motion, whereby the skins are caused to redescend into the
tannic solutions, dropping from the mushroom shaped heads from which they were
suspended; so that all the skins contained in the cylinder are thus plunged into
the tannic juice.
The apparatus employed is preferably three metres in diameter and two metres
long, and provided with four reservoirs containing 250 kilogrammes of 20° con-
centrated extract each.
These particulars, however, as before stated, are given here only by way of
example, and the description of the method, too, is merely intended to serve as an
illustration of the practical use of the invention.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:-
1. An apparatus for rapidly tanning skins and hides by causing the enrichment
of the tannic juice in operation in an automatic manner in proportion as its
strength is exhausted, without allowing it to come into contact with the external
atmosphere, mainly characterised by the addition to a rotary drum of a variable
number of reservoirs connected and revolving therewith; such reservoirs con-
taining concentrated extracts and communicating with the interior of the drum
by means of valves the rods of which project outwards and are adapted to meet a
stationary piece, as the drum revolves, whereby they cause the valves to open and
a certain amount of the liquor contained in the reservoirs to be automatically

page_text: admitted into the interior of the drum; the position of the said stationary piece
being adjustable so as to enable the quantity of liquor supplied to be varied at
will, as above described with reference to the accompanying drawing.
2. In combination with a rotary chamber or drum for tanning skins or hides,
intended to remain hermetically closed, a device enabling the richness or strength
of the juice in operation to be at any moment ascertained or tested; mainly con-
sisting of a test tube containing a tannometer and communicating with one end of
a concentric tube placed in one of the trunnions of the said drum, though indepen-
dent thereof and terminating in a coil or serpentine located in the interior of the
drum; the rotation of this serpentine being independent of that of the drum and
produced by suitable shafting or other driving gear; and the test tube communi-
cating also with the drum through the other trunnion in such a manner that a
continuous current of liquor is ensured whilst the drum is rotating; all as above
described with reference to the accompanying drawing.
3. An apparatus for rapidly effecting the tanning of hides and skins and
enabling the tannic juice to be maintained at the desired degree of concentration,
by providing means for ascertaining at any time the richness or strength of the
liquid, without the necessity of opening the apparatus; mainly consisting of a
rotary drum provided with feeding reservoirs containing concentrated extracts
and adapted to be placed in communication with the said drum automatically, as
described in the First Claim; in combination with an arrangement enabling a
continuous current of liquid to be circulated in a test glass wherein is located a
tannometer or a densimeter of any suitable construction; as described in the Second
Claim the said drum being provided with doors for the admission of the hides
to be tanned and internally fitted with pegs of mushroom-shape; all as above
described, with reference to the accompanying drawing.
9.
4. A tanning bath consisting of the proportions stated and employed substan-
tially in the manner hereinbefore described.
5. A rapid tanning apparatus, either in its complete form or in its details, sub-
stantially as above described and illustrated in the accompanying drawing.
Dated this 14th day of April 1898.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.