Improvements in and Apparatus or Means for the Tanning of Hides, Skins, or other Leather Goods.
Year: 1889

page_text: Date of Application, 13th June, 1889
Complete Specification Left, 14th Apr., 1890-Accepted, 17th May, 1890
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus or Means for the Tanning of Hides,
Skins, or other Leather Goods.
We, BENJAMIN NICHOLSON of The Torrs, South Norwood, in the County of Surrey,
Gentleman, and THOMAS PALMER B. Sc. of 85 Wool Exchange in the City of London,
Analytical and Consulting Chemist, do hereby declare the nature of this invention to
be as follows:-
In the ordinary method of drum tanning the hides skins or leather goods are put
into a drum or vessel to which the tanning liquors are supplied, the drum or vessel being
closed and rotated the hides or skins thereby being continually lifted and then falling
into or through the liquor which is in a continual state of agitation. While it cannot
be denied that the time occupied in the tannage of the goods is enormously diminished
the leather is neither of the same texture nor of as good character as that produced by
other methods, fermentive and other destructive influence take place at the expense
of the tanning liquor which becomes rapidly sour and unfit for use, besides becoming
charged with quantities of gelatinous and other bodies removed from the hides or skins.
Essence of turpentine (Soleine), other chemicals and even electricity have been
employed for the prevention of this damaging effect, the removal of which must of
necessity considerably increase the rate at which tanning can be effected. The continual
knocking about of the hides or skins however is extremely detrimental to the leather,
inasmuch as it causes the grain to rise and become wrinkled to such an extent that
removal in the finishing process is next to impossible, the leather works up soft,
rapidly absorbs water and becomes equally rapidly saturated. The continual
knocking about also prevents the hides or skins from absorbing and assimilating
those substances which go to give weight, and produce solidity and in consequence
the leather is porous and open.
Now this invention consists in not only providing means within the cylinder or
drum for the suspension of the hides or skins to be tanned, but also using such means
of suspension as the conductors of electrical currents.
The hides or skins to be tanned may be hung as described in the Specifications of
Patents No. 3108 of 1885 and 3108* 1885 from (preferably) Muntz metal or gun
metal rods which pass through the whole length of the cylinder or drum and through
the heads the points of contact between the rods and cylinder or drum walls being
insulated, by some non-conducting material, the external ends being secured by nuts
and plates of (preferably) Muntz metal or gun-metal. These rods serve to suspend
the hides or skins and constitute conductors of the electrical current and also act as
stay rods, and thereby strengthen the heads. The hides or skins being suspended by
their corners from rods within the drum or cylinder, the tanning liquor is admitted
from the supply tanks until the drum or cylinder is about half full. The whole is
then set in motion by suitable driving gear, and during the process the hides or skins
are alternately exposed to the action of the liquor and an air current which is forced
or sucked through the space above the liquor in the drum or cylinder to which it is
conducted by an arrangement which may be like that described in the Specification of
my application for patent No. 1345 of 1889. The admission of air may after a time
be stopped, and a vacuum be formed in the cylinder or drum by means of an air
pump, the rotation of the cylinder or drum being continued the hides or skins are
consequently then submitted alternately to the action of the liquor and the vacuum
the latter causing the pores of the hides or skins to open so as to allow the spent
liquor to escape. Sometimes the hides or skins may be subjected to an air pressure
within the cylinder or drum but this is mostly to be resorted to when the liquor has
been, or is being, run off preparatory to a new and stronger supply being admitted
which should at all times take place under vacuum,

page_text: These operations of alternately subjecting the goods to be tanned to the action of
the liquor and the air and to the action of the liquor and a vacuum with occasional
air pressure if desired are repeated as often as may be found necessary, the duration
of each operation varying in accordance with the desire of the operator, being entirely
under control, fresh liquor being from time to time introduced into the cylinder
either from the tanks or from one cylinder to another the spent liquor being run off
to the leaching vats, or colourers as desired.
:
This transfer may be effected either when the cylinders or drums are rotating, or
when they are at rest. Thus two cylinders in connection with each other one of
which is empty of liquor a vacuum is formed in the empty one, whilst an air pressure
is exerted in the one from which the liquor is to be forced, the consequence is that
the liquor is transferred from one cylinder to the other. In practice a set of four or
more cylinders fitted as described may be all connected with an air pump a force
pump and the leaching vats or tanks, so that by simply opening and closing cocks, the
liquor from any one cylinder can be transferred to any other cylinder or be run off to
the leaching vats as desired. The air pump and force pump will serve for producing
a vacuum and a pressure of compressed air in any of the cylinders as required, whilst
an air current is passing through other cylinders at the same time that an interchange
of liquors is taking place in others.
It is found desirable to combine with the cylinders clarifying vessels into which the
liquor may be run if found necessary to filter it, it can then be transferred to one of
the other cylinders until finally spent, or it can be sent into the leaching vats, or to
the colouring pits as desired.
•
We have referred to the suspending of the hides or skins within a circular rotating
drum or cylinder but this Invention is not restricted thereto. For example taking a
box or pit as described under the Specification of my Patent No. 13636 I place
within it a frame or carrier fitted as herein before described with metal rods on which
the hides or skins are suspended and to this frame or carrier I impart motion by
means of driving gear the outer pit or casing being filled to any desired height by
the operator but under the ordinary circumstances kept about half full of tan liquor
the hides or skins being caused to rotate or being left stationary if desired. The
outer casing is made so that it may be closed hermetically. This form of applying
the Invention may be used in the ordinary tan yard pits, the frame being lifted in or
out, for loading or unloading. The motion given to the hides and frame may be
rotary which may be given by means of a worm and worm wheel, the latter being
attached to a spindle passing down a tube at the side of the pit, and working
into a worm wheel attached to the frame or carrier. Or the frame or carrier
may be caused to swing on its axis by means of an eccentric or crank attachment
or the goods may be stationary and the liquor be caused to move by means for
instance of a rocker placed on the bottom and actuated by means of a crank or
eccentric motion.
The top of the pit or tank may be so fitted as to allow of its being covered so that
a vacuum or air current or fluid pressure of any kind may be exerted within the pit.
The fluid pressure may be exerted by atmospheric air charged or not with any gas
or gaseous or vaporous agent capable of allaying or arresting fermentive action, as
for example, sulphurous acid gas, turpentine hydrogen peroxide or the like, or
which may possess drying bleaching or absorbent effects as for example the fumes of
sulphur or there may be added as desired to the tanning liquor substances which are
conducive to the arrestation of fermentive changes. A current of electricity is we
believe an inducement to the operation of tanning inasmuch as it reduces fermentive
action, and increases the power and rate of absorption of the hides or skins themselves,
thereby reducing the time required for their conversion into leather. In order to
introduce such current there is placed on the nut or bolt ends of the rods which pass
through the cylinder and which may be fitted on to the ends themselves a series of
specially constructed radius plates of some good conductor of electricity by preference
brass, gun metal or copper the said plates being constructed so as to make and break
contact by the insertion of thin strips of sheet lead to every half to one inch of brass

page_text: or copper surface. For instance there are usually eight rods in a cylinder, so in that
case there will be 16 of these radius plates, two plates to each rod one at each end or
the rim of the drum or cylinder may be surrounded with a ring of brass copper or
some other good conductor, or the bolt heads may be brought into connection with a
nonconductor boss of vulcanite or the like which may be provided with knobs or
plates of some good conductor the said boss revolving on the axle of the drum or
cylinder at both ends.
The electrical connections from the battery, or other generator of electricity may
be made by binding screws in the usual manner, from which the current may be
conducted to the radius plates, which is done by copper comb, steel brushes or
spring electrodes or in the same manner to the rim, or axle conductors. The
arrangement is applied to both ends of the drum or cylinder.
It may be found advisable to fit a suitable commutator so that the current of
electricity may be under thorough command also that the direction of such current
may be changed as desired from end to end of the cylinder drum or rotating
frame.
A switch of ebonite with a metal core supported between two metal columns in
connection with a battery or other electrical generator and studded with two metallic
knobs, to make and break contact inay be employed.
The charging by the electric current is arranged so that the portion of the hide or
skin passing through the liquor receives the electrical current and as every portion of
hide or skin enters the bath it becomes electrolized while the portions of hide or skin
only receive that which is communicated to them through the other parts being
electrolized no actual contact with the rods taking place until the rod has passed the
level of the liquor.
It is preferred that the goods should represent the positive pole and the liquor the
negative pole to effect which the rods are caused to act as the conveyers of the former,
these rods being covered with an indiarubber (or equivalent) tube in which are holes
to allow of the hooks or hide attachers passing.
The negative communication may be made by means of circular plates or studs
which pass through the cylinder and are in communication with the liquor, this
connection may be continuous if desired but for convenience and, seeing that the
current may be required to be changed in its direction, both ends of the cylinder
should be made alike.
Or the wires from the contact breaker may be passed on to the tube fitting passing
through the axle at either end and from thence into the liquor.
The effect of the current of positive electricity when passed into a solution of tannic
acid or other organic compound being to decompose such substance or compound,
the bides or skins are made to represent that pole which has contact only when the
goods are in or out of the liquor, at the will of the operator which is regulated by
means of the commutator and direction of the current which also admits of the whole
current being thrown off without disconnecting the battery or other electrical
generator..
Dated this 13th day of June 1889.
COMPLETE SPECIFICATION.
Improvements in and Apparatus or Means for the Tanning of Hides,
Skins, or other Leather Goods.
We BENJAMIN NICHOLSON of The Torrs South Norwood in the County of Surrey
Gentleman and THOMAS PALMER B. Sc. of 85 Wool Exchange in the City of London
Analytical and Consulting Chemist 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 ordinary method of drum tanning the hides skins or leather goods are put

page_text: into a drum or vessel to which the tanning liquors are supplied the drum or vessel
being then closed and rotated the hides or skins thereby being continually lifted and
then falling into or through the liquor which is in a continual state of agitation. The
continual knocking about of the hides or skins is extremely detrimental to the leather
inasmuch as it causes the grain to rise and become wrinkled to such an extent that
removal in the finishing process is next to impossible, the leather works up soft,
rapidly absorbs water and becomes equally rapidly saturated. The continual
knocking about also prevents the hides or skins from absorbing and assimilating
those substances which go to give weight and produce solidity and in consequence
the leather is porous and open.
Now this Invention consists in not only providing means within the cylinder or
drum for the suspension of the hides or skins to be tanned, but also using such
means of suspension as the conductors of electrical currents.
According to this Invention the hides are suspended on rods which pass through
the length of the cylinder or drum and through the heads thereof. The points of contact
between the rods and cylinder or drum heads are insulated by some non-conducting
material interposed between the drum heads and the external ends of these rods and
the nuts and plates of Muntz metal or gun metal by which they are secured in
position.
These rods constitute not only stay rods to strengthen the drum but also
conductors of the electrical currents to the hides or skins. The hides or skins are
suspended by their corners from these rods the tanning liquor is admitted and the
drum rotated as described in the Specification to Letters Patent dated 24th January
1889 No. 1345.
Or the hides or skins may be placed within a frame or carrier enclosed in a pit or
outer casing and provided with metal rods on which to suspend the hides or skins and
the casing being filled to any desired height with tan liquor the hides or skins are
caused to rotate therein as described in the Specification to Letters Patent dated
October 25th 1886 No. 13636.
Currents of electricity we believe accelerate the operation of tanning inasmuch that
thereby fermentive action is reduced and the power and rate of absorption of the
hides or skins is increased thus reducing the time required for their conversion into
leather. In order to introduce such currents of electricity according to our Invention
there is provided in connection with the nuts on the ends of the rods on which the
hides are suspended radius plates or conducting wires in connection with a plate or
with plates arranged so as to make and break contact at the required periods. For
instance there are usually eight rods in a cylinder so in that case there will be sixteen
of these radius plates or conducting wires one to each end of each rod or instead
thereof the rim of the drum or cylinder may be surrounded with a ring of brass
copper or some other good conductor of electricity or the ends of the rod may be
brought into connection with a nonconducting boss of vulcanite or the like which may
be provided with knobs or plates of some good conductor the said boss revolving on
the axle of the drum or cylinder a special feature of this Invention being that the
contact surfaces for conducting the electric current are so arranged that the current
passes through those supporting rods only that are not immersed in the tanning
liquor.
*The electrical connections from the battery or other generator of electricity may be
made by binding screws in the usual manner from which the current may be
conducted to the radius plates or wires by any suitable means.
A suitable commutator may be provided so that the current of electricity may be
under thorough command and be introduced into the cylinder drum or rotating frame
in either direction.
A switch of ebonite with a metal core supported between two metal columns in
connection with a battery or other electrical generator and studded with two metallic
knobs to break and make contact may be employed.
It is preferred that the goods should represent the positive pole and the liquor the
negative pole as the effect of passing positive currents of electricity directly into a

page_text: solution of tannic acid or other organic compound is to decompose such substance or
compound consequently we prefer to connect the hides or skins by their supports to
the positive pole of the battery or other source of electricity and to complete the circuit
through the hides only when the rods carrying the goods are out of the liquor but if
desired the direction of the current may be reversed by means of a commutator or
switch.
The accompanying drawing represents in longitudinal section a tanning drum or
cylinder provided with an arrangement according to our Invention for introducing
currents of electricity into the tanning liquor through the hides or skins. A is the
tanning drum mounted in bearings B and caused to rotate therein by gearing or other
convenient means. The heads of the drum are connected together by tie rods D
on which the hides or skins to be tanned are suspended.
The ends of the tie rods D are insulated from the drum heads B as shewn at E by
any suitable insulating material and are each provided with or connected to a plate
or washer F of brass copper or other suitable material electrically connected by
wires G or otherwise to spring contact pieces H on a boss I of insulating material
mounted on the axis of the drum: The contact pieces H when the drum is rotating
make contacts consecutively with a plate K which is connected with one of the poles
(preferably the positive pole) of a battery L or other source of electricity. This
plate K is preferably curved or of semi-circular form and may be fixed as shewn to
the standard M carrying the bearings in which the axis of the drum relates or it may
be otherwise arranged, it is essential however that it be situated so that only the
contact pieces H in connection with the rods D which are not inserted in the liquor
are ever in contact with the plate K. Inside the drum head is a circular plate or
ring N which is always in contact with the liquor in the drum and this ring or plate
is metallically connected to a similar ring or plate O fixed to the exterior surface of
the drum head C. Against this latter ring or plate bears a spring contact piece P
which is connected to the opposite pole (preferably the negative pole) of the battery L
to that to which the plate K is connected.
It will thus be seen that currents of electricity from the battery L will pass through
only the rods D which are not immersed in the liquor as only those contacts H which
are in connection with these rods are ever in contact with the plate K consequently
the hides carried by the said rods constitute a positive electrode whilst the liquid in
the drum constitutes the negative electrode and consequently the hides become
electrolized. As the drum rotates the several rods D are consecutively brought
into electrical contact with the plate K as the said rods rise out of the liquor the
contacts being likewise consecutively broken as the rods enter the liquor. The
current through the liquor in the drum however is continuous as the plate N on the
interior of the drum head C is always immersed or partially immersed in the said
liquor the whole of the hides carried by the several rods being then brought under the
electrolytical action.
The arrangement herein before described may be applied to one end only of the
drum or at both ends thereof as shewn in the drawing.
Q is a commutator of ordinary construction by means of which the direction of
the current from the generator may be reversed or cut off from the tanning drum
when required.
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:-
First In apparatus for tanning hides or skins a rotating drum or vessel provided
in the interior with rods on which to support the hides or skins while being tanned
the said rods serving as conductors of electricity to the hides substantially as
herein before described with reference to the accompanying drawings.
Second-In or connected with apparatus for tannings hides or skins means
whereby currents of electricity are conducted to the hides only when the rods by

page_text: which they are supported are not immersed in the tanning liquor substantially as
hereinbefore described.
Third-The combination and arrangement of parts constituting means for
introducing currents of electricity into hides or skins during the process of
tanning substantially as hereinbefore described and illustrated by the accompanying
drawings.
Dated thin 10th d
J
11000
B. NICHOLSON.
THOS. PALMER, B. Sc.