AN IMPROVED PROCESS OF TANNING
Year: 1855

page_text: LETTERS PATENT to William Edward Newton, of the Office for Patents.
66, Chancery. Lane, in the County of Middlesex, Civil Engineer, for the
Invention of "AN IMPROVED PROCESS OF TANNING."-A communication
from Charles Chrétien Knoderez, of Strasbourg, Leather Manufacturer.
Sealed the 10th June 1856, and dated the 29th December 1855.
PROVISIONAL SPECIFICATION left by the said William Edward Newton
at the Office of the Commissioners of Patents, with his Petition, on the
29th December 1855.
I, WILLIAM EDWARD NEWTON, of the Office for Patents; 66, Chancery Lane,
in the County of Middlesex,. Civil Engineer, do hereby declare the nature of
the said Invention for AN IMPROVED PROCESS OF TANNING, to be as follows:-
In the ordinary process of tanning skins and hides these articles are steeped
for many weeks or months (the length of time depending upon the size and
thickness of the skin) in a tanning liquid, consisting usually of water and
bark reduced to powder. This liquid is contained in vats or pits made in the
ground, and the skins after remaining immersed therein for a considerable
length of time, at last become perfectly tanned and converted into leather.
As it requires several months to complete the tanning operation on thick and
heavy skins, various attempts have been made from time to time to so modify
or improve the modus operandi of tanning, that the required effect may
obtained in much less time, and thereby effect a considerable economy. The
be

page_text: object of the present Invention is also to effect the same desirable result;
and this is obtained by operating on the skins in closed wooden vessels or
cylinders, which are made to rotate on their axes. These vessels or cylinders
may be made of any convenient size, according to the description of skins
they are intended to contain. It has been found that for large skins or hides,
such as ox, horse, bullock, or cow hides or skins, the vessels may be made
about ten feet in diameter and length; while for smaller skins, the vessels need
not be larger than from six to seven feet long, and the same in diameter.
The skins are placed in these cylinders, and an extract of tan bark supplied
thereto, a small quantity of bark being also added. When the skins have
absorbed all the tanning principle, more tan juice and bark may be added, and
after a few days the skins may be removed to another vessel, where they
must be subjected to a still stronger extract of tan and a larger quantity of
bark. By conducting the process on a system of rotation, that is, putting the
fresh skins into to the weaker and partially spent or exhausted solutions or
extracts, all the tanning principle will be absorbed, and a considerable economy
over the old process will be effected. By the rotation of the cylinders and the
motion of the skins therein, the tan 'bark will be reduced to a paste, and a
certain amount of heat will be generated by the friction of the skins against
each other, and the operation thereby facilitated. I make extracts of the
bark of different degrees of strength, according to the purposes for which these
extracts are to be employed, and such extracts may be run from the tun or
reservoir into the tanning cylinders..
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Edward Newton in the Great Seal Patent Office
on the 28th June 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the County
of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of December, in the year of our
Lord One thousand eight hundred and fifty-five, in the nineteenth
year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said William Edward Newton, Her special license that I, the said William
Edward Newton, my executors, administrators, and assigns, or such others as
I, the said William Edward Newton, my executors, administrators, and assigns,

page_text: should at any time agree with, and no others, from time to time and at
all times thereafter. during the terin 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
"AN IMPROVED PROCESS OF TANNING," being a communication from Charles
Chrétien Knoderez, of Strasbourg, Leather Manufacturer, upon the condition
(amongst others) that I, the said William Edward Newton, 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 immediately after the date of the said
Letters Patent.
:
NOW KNOW YE, that I;, the said William Edward Newton, 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, reference being had to the Drawing hereunto annexed,
and to the letters and figures marked thereon (that is to say):
In the ordinary process of tanning skins and hides these articles are steeped
for, many weeks or months (the length of time depending upon the size and
thickness of the skin) in, a tanning liquid, consisting usually, of water and
bark reduced to powder. This liquid is contained in vats or pits made in the
ground, and the skins after remaining immersed therein for a, considerable
length of time, at last become perfectly, tanned and converted into leather,
As it requires several months to complete the tanning operation on thick and
heavy.skins, various attempts, have been made from time to time so to modify
or improve the modus operandi of tanning, as, to expedite the operation, and
thereby effect an economy in, the process. The object of the present Invention
is also to attain the same,desirable result; and this it is proposed to effect by
operating on the skins, in closed, wooden vessels or cylinders, which are made
to rotate on their, axes.. These, vessels or cylinders may be made of any
convenient size, according to the description of skins they are intended to
contain:
It has been found, that for large skins. or hides, such as ox, horse, bullock,
or cow hides or skins, the vessels, may be made about ten feet in diameter
and length; while for smaller skins, the vessels need not be larger than from
six to seven feet long, and the same in diameter. The skins are placed in
these cylinders, and an extract of tan bark is supplied thereto, a small
quantity of bark, being, also added. When the skins have absorbed. all the
tanning principle, more tan juice and bark may be added, and after. a few days

page_text: the skins may be removed to another vessel, where they must be subjected to
a still stronger extract of tau and a larger quantity of bark. By conducting;
the process on a rotative system, that is, putting the fresh skins into the
weaker and partially spent or exhausted solutions or extracts, all the tanning
principle will be absorbed, and a considerable economy over the old process
will be effected. By the rotation of the cylinders and the motion of the skins
therein, the tan bark will be reduced to a paste, and a certain amount of heat
will be generated by the friction of the skins against each other, and the
operation will be thereby facilitated. Extracts of the bark are prepared of
different degrees of strength, according to the purposes for which they are to.
be employed, and such extracts may be run from the tun or reservoir into the
tanning cylinders. These cylinders are to be at first about half filled with
bark liquor marking 0 on the tanninometer; to this liquor, bark is to be added
in the proportion of about half a pound to every small skin or two pounds for
every large skin. The tanning cylinder is then hermetically closed, and made
to rotate at a speed of about from twelve to fifteen revolutions per minute.
This is continued for twenty-four hours, after which a like quantity of bark is
again added to the liquor, and the operation is continued in the same manuer
during three or four days, at the expiration of which time the skins are in the
same condition as if they had been submitted to three steepings. When the
skins have arrived at this stage of the process, they may, according to cir-
cumstances, be shifted into other barrels or cylinders, supplied with tanning
liquor marking from one to two degrees, according to the nature of the skins;
and the same quantity of bark may be added which they received at the
commencement; or the skins may be left in the same vessels, and the quantity
of bark first placed therein may be doubled, the number of hours which they
are made to rotate being reduced, especially, when in consequence of the
continual friction, the liquor has arrived at a temperature of from seventeen to
twenty degrees; this result being obtained, the rotation of the vessels is only
continued from two to six hours out of the twenty-four, according to the
season.
.
For small hides or skins previously thinned by splitting, calf skins, or
square cow or other hides or small skins, such as those used for cutting out
legs of boots or vamps, the tanning process may be completed in from fifteen
to forty days without changing the vessels, by contriving to add small
quantities of bark, as the tannin of that already supplied is absorbed by the
skins.
For large skins, such as cow 'and ox hides, when they have arrived. at such
a stage of the process as would be the case if they had received the powdered

page_text: bark in the tan pit, they must be shifted into. a vessel supplied with liquor
marking from two to three degrees on the tanninometer, and in the ratio of
from thirty to sixty pounds of bark for every skin, according to the quantity
of this latter and the thickness or the kind of skins operated upon. The
rotation of the tanning vessels is after this only continued for from two to
eight hours out of the twenty-four, and these vessels must not be opened for
a fortnight.. At the expiration of this time the tanning process will be found
to have advanced so far as to render it desirable to remove the skins from this
vessel..
Supposing light or small cow or ox hides to be operated upon, the tanning
operation would be completed within this time, but if the skins are more than
the average or middling size or thickness, the same operation as above
described must be recommenced, and the tanning operation will certainly be
completed at the expiration of the second fortnight. If, on the contrary,
large strong hides are required to be. tanned, they must be supplied a third
time with bark; and operated upon during another fortnight in order perfectly
to tan them. With regard to, hides for producing leather of great thickness,
such, for instance, as is required for driving bands for machinery, these hides
are to be supplied with bark in the proportion of from sixty to eighty pounds
for every hide, four successive times; but instead of continuing the operation
during a fortnight only after each successive change of bark, they are left in
the vessel for a period of three weeks, being only caused to rotate during six
hours out of the twenty-four.
- In proceeding according to this new system, when the tanning apparatus is
in full operation, the skins on coming from the first soaking operation are not
put into fresh liquor, and do not receive fresh bark, but are put into vessels,
the tanning liquor of which is nearly exhausted, which they will absorb in from
twenty-four to forty-eight hours, if constantly turned. The absorption being
complete, the vessel is emptied, and being supplied with fresh liquor and. bark,
skins in a more advanced stage of the process are supplied thereto.
With regard to those mentioned at the commencement of this paragraph,
they are put into a vessel containing bark and tan liquor somewhat stronger
than that in which they had been previously immersed, and they are submitted
continuously to the tanning process, until it is observed that they are no longer
affected;. they are then shifted into a vessel which has operated during a
Tortnight, and in which they are rotated for from six to twelve hours out of the
twenty-four. By proceeding in this manner, large skins will, after remaining
for from, ten to fifteen days in this vessel, be as much advanced as if they had
been submitted to a first charge in the tau pit.

page_text: From the above explanations, it will be evident that besides the celerity of
the tanning process, one of the principal advantages of this improved system
consists in doing away with the barley process and the tan pits, a more perfect
swelling or thickening of the hides being at the same time obtained without
manipulation, and also in advancing the tanning process to the same stage
as if submitted to the first charge of bark and tan, and this without the
employment of two pounds of fresh bark or tan liquor; and for obtaining
this result it- s only essential to observe one thing, which is to operate
gradually, in order not to act too powerfully upon the skins on their coming
from the soaking process.
་ ས
"It is necessary, in a word, to follow absolutely the same principles as in
ordinary 'tanning, the conditions which are advantageous for the one, being also
suitable to the other. In the above-described process, the following five great.
difficulties have been overcome:
i First, the production of an apparatus requiring the least possible amount of
motive force, and which, while it is required to be capable of supporting an
enormous weight, must be employed without the use of even the smallest
portion of iron in the interior of the machines
'Second, to obtain a very prompt and at the same time gradual decomposition
of the tanning matter.
Third, to produce à natural heat, variable at pleasure, according to the
requirements of the manufacture and the quality of the skins.
Fourth, to prevent the contact of air with the tanning. matter.
Fifth, to utilize every particle of the tannin contained in the tanning matter
employed.
All these advantages are perfectly attained by the employment of barrels
or tanning cylinders, and of accessory apparatus, similar to that represented
in the accompanying Drawing. In fact, the large vessels are capable of
containing from eighteen to twenty thousand pounds weight of skins, bark,
and liquor, without having the least particle of iron in the interior, and
requiring comparatively but a very small amount of motive power to
drive them.
A
The decomposition of the bark is effected gradually, and yet very 'speedily,
as in consequence of the rotation, and the friction thereby generated, the
bark is ultimately reduced to a paste, the tanning principle of which is
readily absorbed by the liquid, this latter being forced into continual contact
with all its molecules.
At the same time that (in consequence of the rotation) the decomposition of
the bark is effected gradually, and nevertheless with great celerity, the friction

page_text: also produces a natural heat, the intensity of: which may be modified by
causing the cylinders to revolve during a greater or less length of time,
according to the requirements of the manufacture. It is this heat which so
greatly facilitates the combination of the tannin with the gelatine contained in
the cellular tissue of the skins.
** :
The contact of the air with the bark and liquor, which is one of the
principal causes of the slowness of the process of pit tanning, and also of the
large quantity of bark expended in the process (its effect being to convert a
great portion of the tannic acid of bark or other tanning matters into gallic
acid) will be of necessity prevented, as the tanning cylinders being nearly full
will merely contain a very small quantity of air, which being very speedily
decomposed and incapable of renewal, cannot consequently have any appreciable
influence upon the tanning process...
......
Lastly, the whole of the tannin contained in the bark is "utilized, not only
because, as above stated, it is reduced to a paste, but espécially because'as the
bark and liquor contained in a cylinder lose their power, the skins which have
absorbed all that their 'condition allowed them to absorb, are replaced by
skins in a less advanced stage, and consequently more ready to absorb the
tanning principle.
....
In order, however, that the nature of these improvements may be the better
understood, I have represented in the accompanying Drawing the arrangement
of apparatus which the Inventor prefers to employ for the purpose of carrying
out his Invention.
Figure 1 is a vertical section, and Figure 2' a horizontal section of the
same; similar letters of reference indicating like parts in both these Figures.
It will, however, of course be understood that I do not confine myself to
this arrangement, as it may be variously modified according to the nature of
the work required, or the locality in which it is carried on, without departing
from the nature and object of the Invention. For instance, in the arrangement
herein represented and described, it is the peculiar situation of the apparatus,
and the direction of the current of water, which has necessitated the division of
the works into two distinct buildings, between which the driving power is
placed, consisting of two water wheels B and C, set in motion by a common
stream; the left-hand one B, is of larger dimensions, and is used to impart
> motion to the apparatus contained in the principal building, while the smaller
one C. is employed to drive the smaller and lighter apparatus in tlie small
building.
The apparatus is composed of a fulling vessel or barrel A, in which the
tanned skins are placed for the purpose of being fulled or thickened.; of large

page_text: vessels 1, 2, 3, 4, about nine feet long, and of the same'diameter for containing
large skins to be tanned according to the improved plan; and of. eight smaller.
vessels 5, 6, 7, 8, 9, 10, 11, and 12, for small skins about six feet in length, and
the same in diameter.
All these vessels have rotatory motion communicated to them by means of
the water wheels B and C; the first of which B. transmits motion to a hori-
zontal shaft a, by means of toothed wheels b and c. This shaft a is provided
with bevil pinions d taking into bevil wheels e, keyed upon the shafts of the
vessels 1, 2, and 3, by which means they are caused to rotate at a speed of
about nine or ten revolutions per minute. Upon the shaft a are also mounted
three pullies f. f. f, which, by means of driving bands g, communicate motion
to the small vessels 5, 6, and 7, the speed of which, as well as those 8, 9, 10,
11, and 12, is about from fourteen to fifteen revolutions per minute. The
second water wheel C communicates motion to the shaft a¹, by. means of the
toothed wheels 61 and c, and thence to the vessels 7, 8; 9, 10, 11, and 12, in
the small building, through the pinions d', wheels e', and pullies f¹, arranged
in a'manner analogous to the apparatus in the main building. In this latter
are also placed the vertical vessels D, which serve for the preparation of the
concentrated bark liquor; they are arranged in a circle round-the vessel E,
with which they communicate by means of pipes h. This vessel E receives
the bark liquor during its preparation, and this liquor is, by means of the
pumps F and G, forced into another vessel, and thence distributed to the
rotating tanning vessels.
In order to 'effect this distribution of the bark liquor, tin pipes H are
arranged in such a manner as to establish an easy communication between
the pumps, the preparation vessels, and each of the rotating tanning vessels
separately.
At the upper part of the large building are placed the tan mills I, and the
bark cutter J, which are driven by means of an intermediate shaft i. Upon
this shaft are mounted a toothed wheel j, a bevil pinion k, and a pulley 1,
which receive motion from the shaft i, by means of the toothed wheels mand
n. The bevil pinion k drives the wheel k¹ of the tan mill, and the bark cutter
receives motion from the pulley . The pumps-receive motion from the prime
mover by means of the pulleys o and o¹, and the cranks p and p¹.
Having now set forth the nature of the Invention of an improved process
of tanning, as-communicated to me by my.foreign correspondent, and explained
the manner of carrying the same into effect, I wish it to be understood that I
do not confine 'myself to the mechanical arrangements above shewn and
described, as they may be varied without departing from the nature and object

page_text: of the Invention; but what I claim as the Invention secured to me under the
above in part recited Letters Patent is, the process or mode of treating skins,
as herein described, or any mere modification thereof, by which the following
advantages are or may be obtained, viz* :-
First, an economy in the time usually employed in the process of tanning.
Second, a saving in the amount of bark required for a given quantity of
hides or skins.
Third, an augmentation of the weight of the manufactured product.
And lastly, an economy of labour over the ordinary process of tanning.
In witness whereof, I, the said William Edward Newton, have hereunto
set my hand and seal, the Twenty-seventh day of June, One thousand
eight hundred and fifty-six.
W. E. NEWTON. (L.S.)