An Improved Process and Apparatus for the Treatment of Raw Hides.
Year: 1895

page_text: Date of Application, 28th Sept., 1895-Accepted, 9th Nov., 1895
An Improved Process and Apparatus for the Treatment of
Raw Hides.
I, AUGUST FRIEDRICHOWITZ DIEHL, of 38 Woerthstrasse Weimar, in the
German Empire, Manufacturer, 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 order to prepare raw hides for tanning it is necessary to subject them to the
action of lime water (lime milk), the object of such treatment being, to loosen the
hairs in the pores of the skin, so as to enable them afterwards to be readily
scraped off. For this purpose, it has been usual hitherto, to allow the hides to
remain at rest in the lime pit, filled with lime water, until the roots of the hair
had undergone the action of the lime to the required extent; and that con-
summation was not generally arrived at for several weeks. Besides, it was
necessary in the course of that operation to open or spread out the hides at
frequent intervals, which, as it involved their exposure to atmospheric air, did not
fail to lead to consequences most damaging to the quality of the hides and most
unpleasant to the operatives employed, whose hands were affected by the lime.
Now the improved process forming the subject of this invention enables the
preparatory treatment of hides intended for tanning to be completed in very short
time, its duration being, in fact, reduced to as many days as it formerly occupied
weeks. In addition to this the novel mode of treatment does not affect the quality
of the hides as strongly as did the old, inasmuch as the lime solution used is a weak
one and is moreover made to act upon the hides only for a comparatively short space
of time, as stated; a good deal of labour and inconvenience being, lastly, obviated
by the avoidance of any handling or manipulation of the hides whilst they are
undergoing the liming process.
Owing to the circumstance that the improved process produces its effects very
rapidly, the intercellular substances of the skin do not become free and soluble,
but continue bound up with the fibres of the skin, whose firmness and power of
resistance they thus enhance, while at the same time ensuring a subsequent increase
of specific gravity.
The whole of these advantages are realised by suspending the raw hides within
a covered vat, the lime water or lime milk contained in which is kept in a state of
continuous metion, so that a uniform, but energetic, washing or rinsing effect is
produced all round the hides.
It will be understood that the same process may be extended to the treatment
of raw hides with other fluids than the one herein specifically referred to. This
would be more particularly the case, for example, in the treatment of the hides with
a solution of sulphide of sodium and with soda and arsenic.
The improved process may be performed by means of apparatus such as the
one shown by way of example in the accompanying drawings, in which Figures 1
and 2 are, respectively, a vertical and horizontal section of the arrangement
referred to. The rat a, of wood stone or concrete is fitted on its opposite sides or
walls, at the top, with two moveable and adjustable hooks or bars e, adapted to
receive the hides (varying in size) which have to be suspended within the vat.
At the bottom of this vat there is arranged a step bearing b which supports the
vertical shaft c. This shaft, below the level of the hides, is fitted with agitating

page_text: or stirring apparatus, such as wings or blades shown at d, which are here supposed
to be four in number, and two of which should be preferably arranged vertically,
while the other two may he inclined as shown at Figure 3; the object of this
arrangement being to impart to the liquor both rotary and an upward bubbling or
whirling motion.
Above the agitating device, a piece of lattice work or wire-netting g should be
placed, in order to prevent. hides which descend to a very low level from touching,
or being touched by, the blades.
When the hides have been suspended from the hooks, within the vat, such vat is
closed by means of the lid fand the shaft c, the upper end of which may be
retained in position by any suitable bearings, is then set in rotary motion either by
hand or machinery. No considerable expenditure of power is required for this
purpose the resistance of the liquid being all that the blades have to overcome.
To prevent the hides from becoming wound around the shaft, such shaft may be
surrounded by a tubular casing.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. A process for the treatment of raw hides with liquids, and more particularly
with lime water, (lime milk) such process mainly consisting in causing the liquor,
contained in the closed vat, such as a, continually to flow round and in so doing
energetically to wash or rinse the hides suspended within the said vat, by being
maintained in a state of constant circular and upward agitation.
2. Apparatus for the performance of the process referred to in the first claim,
mainly consisting of the stirring or agitating device, such as c and d located below
the diaphragm of lattice work or wire gauze, such as g, adapted to set the operative
liquor in a compound rotary and upward whirling motion.
3. The employment of the process covered by the first claim in the treatment of
raw hides with lime water.
4. The employment of the process covered by the first claim in the treatment of
raw hides with arsenic and carbonates of alkalies.
Dated this 28th day of September 1895.
MARKS & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birmingham, Agents for the Applicant.