IMPROVEMENTS IN TANNING, AND IN THE APPARATUS EMPLOYED THEREIN
Year: 1874

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN TANNING, AND IN THE APPARATUS EMPLOYED THEREIN.
-A communication from abroad by Auguste de Méritens, of Paris,
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PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 7th October 1874.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, do hereby declare the nature of the
said Invention for. "IMPROVEMENTS IN TANNING, AND IN THE APPARATUS
EMPLOYED THEREIN," a communication to me from abroad by Auguste de
Méritens, of Paris, in the Republic of France, Civil Engineer, to, be as
follows:-
This Invention relates to a peculiar process of tanning hides or skins
for the purpose of converting the same into leather, and consists in the

page_text: application of electricity to the tanning solutions, and in the employ-
ment of a special arrangement and construction of apparatus in con-
nection therewith, whereby the absorption by such hides or skins of the
tannin is effected more rapidly than heretofore.
In carrying out this Invention the bottom of the tan pit is composed
of a block or slab of conducting carbon or charcoal, or other suitable
insoluble material, or of two or more of such blocks or slabs covered with
a layer of the same substance in a coarsely pulverized condition, a copper
wire coated with gutta percha or other suitable insulating material is
employed, one end of which wire is in contact with the carbon or charcoal,
or its equivalent, whilst the opposite end (the wire being conducted up
the side of the pit to the exterior) is connected to the positive pole of a
battery. Upon the bottom so constructed there is placed a layer of
bark or other suitable tanning material sufficiently impregnated with
water or other liquid, and above this a hide or skin, and then a further
layer of bark or other tanning material and another hide or skin, and
so on in succession; the layers of the tanning material and hides or
skins being arranged alternately to any required number. A sheet or
plate of zinc, in communication with the negative pole of the battery, is
disposed at the upper part of the pit and rests upon a layer of bark or
other tanning material, and above the zinc there is placed a final
layer of such tanning material sufficiently impregnated with liquid, as
herein-before mentioned.
On establishing an electric current a motion takes place between the
two poles through the hides or skius which are contained in the tan
pit, the basic elements proceeding to the negative pole and the acid
elements to the positive pòle, whereby a general molecular motion is
produced and maintained throughout the hides or skins, and the fixing
of the tannin in their pores is effected.
It is preferred to divide each of the poles into two or more surfaces,
according to the depth of the pits and the quantity of hides or skins
which they contain, but it is in all cases essential that the anode com-
municating with the positive pole of the battery should be composed of
an insoluble material.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 7th April 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of October, in the year
of our Lord One thousand eight hundred and seventy-four, in the 38th
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said John Henry Johnson, Her special license that I,
the said John Henry Johnson, my executors, administrators, and assigns,
or such others as I, the said John Henry Johnson, my executors, admi-
nistrators, or 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 "IMPROVEMENTS IN TANNING,
AND IN THE APPARATUS EMPLOYED THEREIN,' a communication to me from
abroad by Auguste Méritens, of Paris, in-the Republic of France, Civil
Engineer, upon the condition (amongst others) that I, the said John
Henry Johnson, my executors or administrators, by an instrument in
writing under my hand and seal, 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 be filed in the
Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
"
.
NOW KNOW YE, that I, the said John Henry Johnson, 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, that is to say :-
The said Invention relates to a peculiar process of tanning hides or
skins for the nurnose of converting the same into leather and consisto

page_text: in the application of electricity to the tanning solutions and in the
employment of a special arrangement and construction of apparatus in
connection therewith, whereby the absorption by such hides or skins of
the tannin is effected more rapidly than heretofore.
If an electric current be caused to traverse a solution of oak, chesnut,
or birch bark, or of any substance containing tannin, in such a manner
that one pole is situate at the bottom of the tan pit or receptacle, and
includes as nearly as possible the whole of the lower surface while
the other pole is situate at the upper surface, and if the hides or
skins to be tanned be placed between the two poles, a continuous
current is established from one pole to the other. The basic elements
being conducted to the negative pole and the acid elements to the
positive pole, a general molecular motion results therefrom, which takes
place throughout the whole of the hides or skins, and traverses them con-
tinually. The absorption of the tannin is then effected under excellent
conditions and much more rapidly than by the ordinary arrangements.
This result which it has been sought to obtain by means of pressure
vacuum or heat may, by the use of this Invention, be attained in a
simpler and more efficient manner. The stoutest hides or skins are
completely tanned in from thirty to thirty-five days, while in the ordinary
pits a steeping for twelve or fifteen months is required. If the tanning
solution and the hides or skins are put in communication with the two
poles of a voltaic battery it is indispensable that the anode should be
insoluble. If the anode were composed of metal, the current by dis-
solving it would produce a metallic tannate which would affect both the
leather itself and the rapidity of the operation of tannin. The com-
bination of the tannin alone with the organic substance would no longer
take place.
In carrying out the said Invention apparatus is employed constructed
and arranged in the following" manner:-The bottom of the tan pit is
composed of a single plate or slab of conducting charcoal, or of a layer
of this charcoal coarsely powdered, covering several plates or slabs of
the same substance. In contact with the charcoal is a copper wire
(covered with gutta percha or other insulating material), which wire
ascends the perpendicular sides of the pit and is connected at the
exterior to the positive pole of the battery. A layer of the bark con-

page_text: taining the tannin is spread, sufficiently impregnated with water upon
the charcoal, upon it is laid a hide, then another layer of bark, upon
this another hide, and so on in succession. At the upper part of the
pit there is placed a sheet of zinc which rests upon the bark, and upon
the zinc is disposed a final layer of damp bark. The negative pole of
the battery is in communication with the zinc.
When the current is established, as the charcoal is not dissolved, a
transporting motion takes place from one pole to the other, traversing.
the hides, and the basic elements are directed to the negative pole, and
the acids to the positive pole. A continual molecular motion throughout
the hides or skins results therefrom and the tannin alone is in action.
By this means the result which it has been unsuccessfully sought to
obtain by the aid of hot or cold pressure a vacuum or centrifugal force
is attained in a rapid and simple manner, videlicet, the tannin is fixed in
the pores of the hides or skins.
It is preferred to divide each pole into several surfaces according to
the depth of the pits and the quantity of hides or skins which they
contain; a saving of time is thereby effected and a more uniform result
obtained throughout the whole of the hides or skins. The principle
remains unchanged, videlicet, the use of an insoluble anode at the
positive pole.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider to
be novel and original and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,-
First. The application and use of electricity to and in the tanning of
hides or skins, as herein-before described.
Second. Constructing tan pits or receptacles for containing a tanning
solution and the hides or skins to be tanned with an insoluble anode in
communication with the positive pole of a voltaic battery or source of
electricity, and a zinc plate or its equivalent in communication with
the negative pole of such battery or source of electricity, the hides or
skins being placed between the two poles, and the apparatus arranged.
5 in such a manner as to cause a general molecular motion throughout

page_text: the hides or skins, and effect the absorption of the tannin by the same,
substantially as herein-before described.
In witness whereof, I, the said John Henry Johnson, have to
this my Specification set my hand and seal, this Seventh day of
April One thousand eight hundred and seventy-five..