IMPROVEMENTS IN THE PROCESS OF AND APPARATUS FOR TANNING
Year: 1857

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
of IMPROVEMENTS IN THE PROCESS OF AND APPARATUS FOR
TANNING." A communication from Mr. Charles Chrétien Knoderer, of
Strasbourg, in the Empire of France, Leather Manufacturer.
Sealed the 18th August 1857, and dated the 12th March 1857.
PROVISIONAL SPECIFICATION left by the said William Edward Newton
at the Office of the Commissioners of Patents, with his Petition, on the
12th March 1857.
I, WILLIAM EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane,
in County of Middlesex, Civil Engineer, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE PROCESS OF AND APPARATUS FOR
TANNING," to be as follows:-
This Invention of improvements in the process of and apparatus for tanning
relates, 1st, to a means of accelerating the process of tanning; and, 2nd, to
improved machinery or apparatus to be used in such process.
The first part of the Invention consists in conducting the tanning operation
in tanks or vessels from which air is exhausted and excluded, and to which
vessels motion may be communicated when required, so as to submit the
hides to a certain amount of friction, which will create or develop heat,
and thereby facilitate the tanning process. When the skins or hides have
been prepared and made ready for the tanning operation, they are placed in
the tank or vessel, and the air is pumped out therefrom. A communication
is then opened between the tank or vessel containing the skins or hides and
another vessel containing the tanning liquor, which will immediately rush
[Price 8d.1

page_text: into the exhausted vessel and penetrate the skins. It is found advisable to
completely fill the vessels, so as to entirely exclude the air, which would act
prejudicially. The operation may either be carried on in fixed tanks or
vessels or in moveable vessels, as above mentioned. It will only be necessary
to observe, that the motion and heat developed thereby has been found in
practice to considerably accelerate the process. It may not, however, always
be convenient to adopt this plan, and when such is the case the fixed tank
or vessel may be employed. In constructing the apparatus it is found
desirable not to use naked iron in such parts of the apparatus as would bring
the metal into contact with the tanning liquor, as the latter would become
discolored thereby.
The plan which the Inventor of the present improvements proposes to
adopt is to construct the vessels internally of wood, prepared in such a manner
with gutta percha or caoutchouc, or a combination of these materials, as to
prevent air from passing through the pores of the wood. Sheets or strips
of gutta percha or caoutchouc may also be adapted to the joints and openings
of the vessels for the same purpose.
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 12th September 1857.
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 Twelfth day of March, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twentieth 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, 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 THE PROCESS OF AND APPARATUS FOR TANNING,"
being a communication from Mr. Charles Chrétien Knoderer, of Strasbourg,

page_text: in the Empire of France, 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 manuer 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) :-
-
This Invention of improvements in the process of and apparatus for tanning
relates, first, to a means of accelerating the process of tanning; and, second,
to improved machinery or apparatus to be used in such process; and consists
in various improvements upon an Luvention for which Letters Patent were
granted to me, bearing date the Twenty-ninth day of December, One
thousand eight hundred and fifty-five.
The first part of the Invention consists in conducting the tanning operation
in tanks or vessels from which air is exhausted and excluded, and to which
vessels motion may be communicated when required, so as to submit the
hides to a certain amount of friction, which will create or develope heat, and
thereby facilitate the tanning process. When the skius or hides have been
prepared and made ready for the tanning operation, they are placed in the
tauk or vessel, and the air is pumped out therefrom. A communication is
then opened between the tank or vessel containing the skins or hides and
another vessel containing the tanning liquor, which will immediately rush
into the exhausted vessel aud penetrate the skins. It is found advisable to
completely fill the vessels, so as to entirely exclude the air, which would act
prejudicially. The operation may either be carried on in fixed tanks or
vessels or in moveable vessels, as above mentioned. It will only be necessary
to observe, that the motion and heat developed thereby have been found in
practice to considerably accelerate the process. It may not, however, always
be convenient to adopt this plan, and when such is the case the fixed tank
or vessel may be employed. In constructing the apparatus it is found
desireable not to use naked iron in such parts of the apparatus as would
bring the metal into contact with the tanning liquor, as the latter would
become discolored thereby. The plan which the Inventor of the present
improvements proposes to adopt is to construct the vessels internally of wood,

page_text: prepared in such a manner with gutta percha or caoutchouc, or a combination
of these materials, as to prevent air from passing through the pores of the
wood. Sheets or strips of gutta percha or caoutchouc may also be adapted
-to the joints and openings of the vessels for the same purpose.
In the Specification of my former Patent above mentioned it was stated
that the principle upon which the improvements were based consisted in ren-
dering the operation of tanning much more speedy and effective by excluding
the air from contact with the tanning liquor and skins immersed therein.
Experiments subsequently made by the Inventor have verified the correctness
of this principle; but it has been found that the means hitherto employed
for carrying it into effect were inadequate to the purpose, as the vessels,
although closed sufficiently tight to prevent the liquid from escaping, were
not sufficiently so to prevent access of air, and as the vessels were never
more than three parts full, and sometimes even less, and consequently con-
tained more air than is necessary for the decomposition of the tannin, the
action which the tannin should have exerted upon the skins was considerably
reduced. As it there fore appeared necessary not only to prevent the contact of
the air with the tanning liquor and hides contained therein, but also to extract
from these latter any air which they might contain, the most effective plan
for obtaining these results seemed to be to perform the tanning operation in
vacuo.
In operating upon a small scale there was no difficulty in effecting this
by means of an air pump and a vessel of glass or copper, but there was
considerable difficulty in working on a large scale according to this plan,
as it was necessary to prevent the tanning liquor from coming into contact
with iron, which blackens it, and also the skius immersed therein. Zinc also
could not be employed, as it is corroded by the tanning liquor. Copper also
is very dear, and has the effect also of darkening the color of the leather.
With regard to wood, it was unsuitable for the purpose on account of its
great porosity, which was found to be a great obstacle to the production of
Wood could not therefore be employed unless its pores were
filled with some substance impervious to air. This result has been obtained
in the most satisfactory manner by the Inventor of the present improvements,
so that by this means the same result is obtained in a stationary vessel and
at the natural temperature as was formerly effected by combining the move-
ments of the vessel therewith, and consequently a much superior result is
obtained with the moveable vessels than was formerly effected, an economy
of seventy-five per cent. of bark being the result in both cases, and the time
necessary for the tanning operation is considerably diminished.
a vacuum.

page_text: In the accompanying Drawing, Fig. 1 is a vertical section of a moveable
vessel or vat suitable for tanning in vacuo, together with its air pump and
other appurtenances; Fig. 2 is a plan view of the same, partly in section;
Fig. 3 is a side or end view thereof; and Figures 4 and 5 are vertical sections
of the air pump detached. The staves A of the vat are made or oak, as well
as the ends B, which are covered on their outside with ribbed plates of iron C,
on which are cast the axles or trunnions a aud a¹, mounted in bearings b.
These axles or trunnions are hollow, the right-hand one al being closed by a
cover c; the left-hand one a is furnished with a brass tube D, communicating
from the air pump to the interior of the vat or vessel. This pipe is provided
with a second pipe E, made of copper, and placed vertically between the end B
of the vessel and the perforated wooden false bottom F, in order to protect it
from the action of the skins when the latter are set in motion by the rotary
movement of the vat or vessel A. The pipes D and E are fixed, and do not
follow the movement of the vessel A, and in order to prevent the air from
re-entering the vessel during its movement, the pipe D is provided with a
shoulder d, and the hollow axle a has a stuffing box e. To this pipe Dis also
attached a vertical pipe G, and a manometer f to indicate the amount of
vacuum produced in the vessel A by means of the air pump H. This pump,
which is shewn detached at Figures 4 and 5, is composed of a cylindrical body
of cast iron, hollowed out or of larger diameter at its upper part, for the
purpose of containing a certain quantity of liquid, which is poured in above
the packing, thus forming an hydraulic joint.
The body of the pump is closed at its lower extremity by a brass cover L,
provided with an air valve 1, and also with two channels or ways m,m(Fig. 5),
one of which communicates by means of the brass pipe M (Fig. 1) with the
pipes D and E inside the vessel A, and the other is closed by a plug, or when
this is removed communicates with a second similar vessel situate at any
suitable distance from the first. The piston N is made of cast iron, and is
furnished with an air valve n, opening inwards for the admission of air.
The piston has a reciprocating motion imparted to it by any suitable motive
power through the rod O attached to the piston; it is also provided with
two lugs o, having brass bearings through which the guide rods P work
when the piston is moved up and down.
The vessel A has two openings P and Q, the first of which P (see Fig. 2)
serves for the introduction of the pipe E, and is closed hermetically by means
of a brass stopper or cover; the second (Q) is a man-hole of brass for the
introduction of the goods to be operated upon, and also for the purpose of
cleaning out the vessel A. Rotary motion is communicated direct to the

page_text: vessel A by means of a driving band upon a pulley R, fixed on to the body
of the vessel A. Between the ends B of the vessel and the two cast-iron
plates Care placed thin sheets of india-rubber, and the outer surface of the
staves of the vessel is covered with two layers of gutta percha, liquefied by
means of a light coal tar oil and linseed oil; this is applied hot by means
of a brush, and caused to enter the pores of the wood by meaus of hot
smoothing irons, the effect of which is, as above stated, to close the pores
of the wood, and consequently to prevent the access of air, so that the
vacuum produced by means of the pump will always remain the same
during the progress of the tanning operation.
Fig. 6 is an elevation, partly in section, of a stationary apparatus for
performing the tanning process in vacuo; Fig 7 is a plan of the same, also
partly in section; Fig. S is an end elevation, also partly in section, of the
same; Fig. 9 is a view, on a larger scale, of the cock adapted to the cover
of the apparatus, by which it is put in communication with the air pump;
and Fig. 10 is a detached view, shewing the method of attaching the cover
to the apparatus.
The tanning vessel or pit is constructed of oak of the best quality; the
planks S of the sides and the cover T are connected together by means of
tongues and grooves. The four sides are attached to the bottom by means of
vertical pieces s, and are united firmly together by means of screws, and by
means of triangular corner pieces s¹, fixed inside by means of zinc nails.
The bottom and cover are held firmly together by means of cross pieces t
(Figures 6 and 8). The cover fits exactly upon the vertical sides of the
vessel, and in order that it may be hermetically closed, a thin strip of india-
rubber is applied to close the joint, and for that purpose is made to cover the
upper part of the sides; the strip is thus firmly compressed between the sides
and the cover by means of a number of screw bolts (see Fig. 10) on the
iron framing, which binds the whole firmly together. The cock v, which is
mounted on the brass plate V, and is shewn detached at Fig. 9, is provided
with the india-rubber pipe et, and serves to establish a communication between
the tanning vessel and the air pump. The plate V is let into the cover, and
is affixed firmly thereto by means of wood screws, a disc of caoutchouc being
interposed between it and the cover. For the purpose of charging and
emptying this tan pit, the cover is lifted off by means of four men with
levers, which they introduce into the iron staple pieces X attached to the
The outer surfaces of the sides, bottom, and cover are payed over
with two coatings of liquefied gutta percha, which is afterwards worked in,
as above described, for the rotating tanning vessel.
cover.

page_text: The manner of conducting the tanning operation is as follows:- The skins
having been steeped, are submitted to strong pressure, in order to squeeze out
as much water from them as possible; they are then thrown into the rotary
vessels first described (Figures 1, 2, and 3), together with the necessary
quantity of bark or other suitable ianuing material. The requisite quantity
of water or liquor is then poured in to wet them properly; the cover q is then
screwed on to the opening Q, and as perfect a vacuum as possible is produced
by means of the air pump. This will cause the pores of the skins to open,
and prepare them for the reception of the tanning material. When as perfect
a vacuum as possible has been produced, the cock y is closed, and to the pas-
sage m is applied a leaden pipe, communicating with a large vat or reservoir
filled with bark liquor of suitable strength, according to the quantity of skins
in the vessel. The other extremity of the tube being immersed in the liquor,
it is only necessary to open the cock and the liquor will be driven with great
force into the tanning vessel by the pressure of the atmosphere. In case the
tanning vessel should be capable of containing more tan liquor than the vat
or reservoir from which it is to be filled, care must be taken to close the cock y
when the vat or reservoir is almost empty, in order to prevent the introduction
of air into the tanning vessel, and fresh liquor must be introduced into the
supply vat in order to fill the tanning vessel. When sufficient liquor has
been introduced into the tanning vessel the cock is to be closed, and motion
is communicated to the tanning vessel by placing the driving band upon the
pulley R; this motion is continued for from a quarter of an hour to an hour,
according to whether the vessel contains calf skins or cow, ox, or bull hides ;
it is then left in repose for from one to three hours, and again put in motion
for a period twice as long as the first time. The operation is thus continued,
diminishing each time the period of repose and augmenting the duration of
motion, until the movement is caused to be continuous.
It will thus be seen that there is a combination of causes to facilitate the
tanning operation, viz-Firstly, the vacuum, which expands the cellular
tissue of the skin, and prevents the formation of gallic acid; secondly, the
movement, which accelerates the decomposition of the bark and effects a con-
tinuous working of the skins; and, thirdly, the heat which is produced by the
movement, and which greatly facilitates the combination of the gelatine
contained in the cellular tissue of the skins with the tannin. By this combined
action the tanning operation is performed in a much ir ore effective and
expeditious manner than heretofore.
Having now described this Invention of "improvements in the process of
and apparatus for tanning," as communicated to me by my foreign correspon-

page_text: dent, I desire it to be understood that what I claim as the Invention secured
to me by the herein-before in part recited Letters l'atent is,
Firstly, the method above shewn and described of performing the operation
of tanning in vacuo, by which the process is performed in a more perfect and
expeditious manner than heretofore.
Secondly, the arrangement and construction of the moveable or stationary
apparatus above shewn and described, or any mere modification thereof.
And, thirdly, the means above shewn and described of making the tanning
vessels air-tight, and preventing the return of air into the vessels after a
vacuum has been produced.
In witness whereof, I, the said William Edward Newton, have hereunto
set my hand and seal, the Tenth day of September, in the year of our
Lord One thousand eight hundred and fifty-seven.
Witness,
J. W. MOFFATT,
66, Chancery Lane.
W. E. NEWTON. (L.S.)