Improvements in the 'Method of and Apparatus for Extracting the Tannin from Bark or other Materials used for Tanning Purposes.
Year: 1889

page_text: Date of Application, 18th Dec., 1889
Complete Specification Left, 18th Sept., 1890-Accepted, 18th Oct., 1890
•
PROVISIONAL SPECIFICATION.
Improvements in the 'Method of and Apparatus for Extracting the
Tannin from Bark or other Materials used for Tanning
Purposes.
We, JOHN HUTCHINGS & WILLIAM NELSON HUTOBINGS both of Howley Tannery,
near Warrington, County of Lancaster, Tanners, do hereby declare the nature of this
invention to be as follows:-
This invention has for its object. an easy thorough and expeditious mode of
extracting the soluble ingredients of tanning material. At present this material is
thrown into a tan-pit and then water added-the stuff swells up considerably and
becomes almost impermeable mass requiring a very long time for the extraction of
the liquor. Now by our experiments we find that 1st the mass must be considerably
subdivided to enable the water to pass through it and extract the contents, easily, and
2nd the vigorous agitation and circulation must be effected.
To effect this object we have found that it is best to separate the tanning material
by pervious partitions and pump the water continuously through these. To carry
this out in a simple manner we have designed the following arrangement. In an
ordinary tanpit of the same construction as tlint now used for dissolving the tannin,
we pilo a large number of baskets partially filled with tanning material, one on the
other in each pit until they nearly roach the top the pile extending all round the
sides of the pit but leaving a hiatus in the centre. In this hiatus we place a trunk
of wood or other suitable material having large orifices in the sides near the bottom
and being open at the top. By means of a pulley placed over the top of this trunk,
a weight formed of stone, concrete, metal, or other suitable material is suspended by
means of a rope worked by a winch or other contrivance. The pit is filled with water
in the usual manner.
In working the pit, the weight is alternately drawn up to the top and allowed to
fall to the bottom of this trunk. This forces the water out of the bottom and up
through the baskets thereby giving very vigorous agitation. The baskets not being
filled tight, even when the material is expanded with the water, the material is
shakon about to some extent in them. In this way a single man with a light winch
or set of winches can work in turn all the dissolving pits of a considerable tanyard
and the tanning material is more thoroughly exhausted and in a vastly less period of
time than by the existing system.
Dated this 17th day of December 1889.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Method of and Apparatus for Extracting the
Tannin from Bark or other Materials used for Tanning
Purposes.
We, JOHN HUTCHINGS and WILLIAM NELSON HUTOHINGS both of Howley Tannery,
near Warrington, County of Lancaster, Tanners, 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 :-
This invention has for its object an easy, thorough and expeditious mode of causing
the liquor to circulate in tan-pits for the purpose of extracting the soluble ingredients
of tanning material, or of bringing the liquor to act with greater effect on the hides.

page_text: In these :-
A is an ordinary tan-pit or leach of any convenient size, say ten feet square and
six feet deep. B B baskets also of any convenient size, the ones we uso in pits of
the dimensions set forth are two feet square outside extreme dimensions and about
eleven inches deep. C is a square wooden trunk of boards two inches thick
enclosing a plunger D, this is a simple strong box of wood fitting the trunk and
about three feet deep partially filled with stones or other weighty matter, and
having a simple pump clack dat bottom. A block of stone, etcetera, having on
the top a square piece of leather fitting the tube, which acts as a single pump clack,
will do equally well. E rope or chain on which plunger D is suspended, this
passes over pulloys F to a rocking beam G which actuates not merely this one
plunger but all the others in the tan-yard by means of ropes; beam G oscillates on
centre H and is rocked by pin I on revolving wheel J. The latter revolves about,
say, ten to twenty times a minute, about thirteen for general purposes is found to
give the best results. K channels hereafter described. L steadying boards holding
the trunks securely in place and forming supports for planks M to walk upon.
An overhead shaft with cams keyed on, one for each plunger, may, in some cases,
be more convenient. It has the advantage of distributing the work to be done in
the course of a revolution of the shaft. For hand working, a simple crank handle
and winch can be used.
The baskets B are of any ordinary structure, we prefer split half inch cane with a
skeleton or ribs of slightly thicker whole cane, as shown in Figure 3. The upper
and lower rims of these baskets are about the same width and are a moderately
good fit, so that the liquor rises or falls through them, being unable to pass between
them easily and in quantity.
The mode of using is as follows:-
The baskets, about half filled with the bark-valonia or other tanning material, are
piled one on the other, filling the pit except the irregularly shaped bottom in which
channels K lead from the centre in a star-like form or otherwise under the baskets.
The pit being nearly filled with baskets, liquor is pumped in, till it is nearly full.
The plunger is set going, alternately sinking to the bottom and rising to a point
a little above the surface of the liquor. As it descends, the clack opens and lets
the liquor through, or, if the plunger be filled with stones, as we sometimes work it,
it forces the liquor out through the radiating or other channels under the baskets
through which it rises; as the plunger rises, the liquor is again sucked back to
below the plunger and the liquor above the plunger has overflowed into the
surrounding baskets. This pumping or ebb and flow goes on till the liquor in the
pit has taken up all the strength from the material which it is capable of doing, a
weaker liquor being substituted at each renewal.'

page_text: When the apparatus is used for tanning hides, the baskets are removed, and the
hides hung vertically or placed horizontally in any convenient manner in the pit. If
placed horizontally, the hides should be kept separated by layers of tanning material
or otherwise. The pumping is then carried on as already described.
The foregoing is an exact description of the apparatus now being worked by us
at the Howley Tannery. It is obvious, however, that any other form of pump or
circulating mechanism that would not choke would do instead of our simple circulator;
further, that the circulation can be in the upward direction only instead of reci-
procating, or in the downward direction only (through the material) but this
latter we do not recommend, as an occasional or constant upward current has a
tendency to lift the material from the basket bottom or the perforated platform upon
which it rests, and thus prevent clogging or choking; also that simple basket work
trays or perforated shelves at intervals could take the place of baskets, and the
invention will work, but not so efficiently, if there be only a single perforated false
bottom and the liquor taken from the top be pumped or circulated through that
false bottom upward in a constant, intermittent or occasionally reversed stream, but
the plan we have set forth after much experimenting, we believe the best for general
tan-yard purposes.
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. The process of extracting the soluble inatters from tanning materials, which
consists in dividing the material to be exhausted of extract into shallow horizontal
layers with spaces between and causing the liquor to circulate vertically through
these layers, substantially as described.
2. The combination of a tan-pit A, a pump or circulator D and means by which
the liquor shall freely leave the pump barrel, circulate through or among the material
containing tannin and again enter the pump, substantially as described.
3. The combination, with a tan-pit, of a series of baskets or platforms upon which
the material is placed in a series of layers, together with means for causing a circula-
tion through these layers preferably alternately upward and downward or altogether
in an upward direction.
4. The mechanism for working the pump or circulator, substantially as and for the
purposes described.
Osos described.
Dated this 17th day of September 1890.
WM. P. THOMPSON & Co.,
Of Liverpool, Nottingham, Manchester, and London, Patent Agents.