AN IMPROVED PROCESS OR METHOD FOR TANNING SKINS, HIDES, &C., AND CONVERTING THEM INTO LEATHER
Year: 1860

page_text: LETTERS PATENT to Andrew Dietz, of the City and State of New York,
United States, for the Invention of "AN IMPROVED PROCESS OR METHOD
FOR TANNING SKINS, HIDES, &C., AND CONVERTING THEM INTO LEATHER."
Sealed the 12th April 1861, and dated the 22nd October 1860.
PROVISIONAL SPECIFICATION left by the said Andrew Dietz at the
Office of the Commissioners of Patents, with his Petition, on the
22nd October 1860.
I, ANDREW DIETZ, of the City and State of New York, United States, do
hereby declare the nature of the said Invention for "AN IMPROVED PROCESS
OR METHOD FOR TANNING SKINS, HIDES, &C., AND CONVERTING THEM INTO LEATHER,"
to be as follows:-
The distinguishing feature or principle of my Invention consists in swelling
the tissues and fibres of the skin or hide previous to and during the process of
tanning by the use of saline liquors, so as to fit the skin to receive the most
easily and effectually the tannic material or principle, and in using, in con-
nection or combination with such saline liquors, tannic liquors of different and
increasing strengths, whereby the centre or inner parts of the skin are tanned
as quickly or nearly so as the outer surfaces, and the whole process of tanning
completed in a much shorter time than by the ordinary methods.
I make a weak liquor of 2° or 3° strength, as measured by the barkometer,

page_text: from any tannic substance, and in such liquor I mix of salt or alum, either
separately or together, in about the proportion of two ounces to the gallon,
and stir the whole together. In this liquor the skin is immersed, and
frequently handled and stirred until the skin has become well saturated, and
the tissues and fibres fully swollen. The saline substances may, however, be
dissolved in water alone without any tannic substance, and the skins saturated
therein before they are immersed in the tannic liquors. The tannic properties
or strength of the liquor in which the skins are immersed is to be increased
from 2° to 4° per day, as indicated by the barkometer, and whenever so
increased the skins are to be well stirred and handled, and such increase in
the strength of the tannic properties of the liquor and handling of the skins is
to be continued until the skin is fully tanned. The particular ratio of increase
of strength is not, however, material, as this will vary according to and should
be somewhat regulated by the capacity of the skins to receive the tannic
elements. The length of time necessary for the complete tanning of the skin
will also vary according to the thickness of the skins and their readiness to
receive the tannin. Sheep skins will be tanned in two or three days, and calf
skins in about eight days, while heavy leather, as cowhide, &c., will require
from thirty to forty days, and sole leather from forty to fifty days. The saline
substances swell the tissues of the skin, and cause them to retain their loose
and spongy nature more completely than if water alone is used, and such
substances thus fit the skins to receive most quickly and effectually the tannic
principle, and the use of weaker tannic liquors at the beginning, and then
stronger and stronger ones, from the fact that liquids of different densities
have a strong tendency to mix with and diffuse themselves through each other,
produces, so to speak, a continued current or movement of such liquors
through the skin, thus causing the interior parts of the skin to be tanned as
fast or nearly so as the outer surfaces, and tanning the whole skin much more
expeditiously.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed s
by the said Andrew Dietz in the Great Seal Patent Office on the
18th April 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
DIETZ, of the City and State of New York, United States, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters 3
Patent, bearing date the Twenty-second day of October, in the year of our

page_text: Lord One thousand eight hundred and sixty, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Andrew Dietz, Her special licence that I, the said Andrew
Dietz, my executors, administrators, and assigns, or such others as I,
the said Andrew Dietz, 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
"AN IMPROVED PROCESS OR METHOD FOR TANNING SKINS, HIDES, &C., AND
CONVERTING THEM INTO LEATHER," upon the condition (amongst others) that I,
the said Andrew Dietz, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, 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 Andrew Dietz, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and
the following
statement, that is to say:-
The distinguishing features of my Invention consist in swelling the tissues
of the skin previous to and during the process of tanning, by the use of saline
liquors, so as to fit the skin to receive the tannic material, and in using, in
connection with the substances employed to swell the tissues, tannic liquors of
different and increasing strengths, whereby the centre or inner parts of the
skin are tanned as quickly or nearly so as the outer surfaces, and the whole
tanned in much shorter time than by the ordinary methods.
The skin is first unhaired and prepared for tanning in any of the usual
methods. The process of tanning is then as follows:-With any tannic
substance I make a weak liquor two or three degrees, as measured by the
barkometer, and in such liquor I put salt and alum, seperate or together,
in about the proportion of two ounces to the gallon, and stir and mix the
whole well together. In this liquor the skin is first immersed, and frequently
handled or stirred. The strength of the tannic properties of the liquor is to
be increased from three to four degrees per day, and such increase may be
made at three or four different times, and in proportional degrees or parts,
and as often as so increased the skin is to be well stirred & handled. The
length of time during which the skins are to be continued in such liquors will

page_text: of course vary according to their thickness. Ordinary sheep skins will be
tanned in two or three days, while calf skins will require about eight days;
for heavy leather, such as harness leather, cowhide, &c., thirty to thirty-five
days will be necessary, and for sole leather from forty to forty-five days will be
required. For the heavier skins also, the strength of the tannic liquors may
be somewhat greater, and for such skins the strength of the tannic liquor need
not be increased so frequently during a day, but such increase need be made
but once a day. The effect of the saline substances or liquors is to swell the
tissues of the skin, and cause them to retain their loose and spongy nature,
and thus fit them to best and quickest receive the tannic material or acid,
which will penetrate the skin more readily than if its pores and interstices
were occupied by merc water. By using also in connection or combination
with such saline substances a weaker tannic liquor at the beginning of the
process of tanning, and then stronger and stronger liquors, the outer surfaces
of the skin are not, as in the ordinary methods of tanning, tanned most
rapidly, and thereby the pores partially or mostly closed before the inner parts
of the skin are changed into leather, but the inner parts of the skin are
reached by each liquor, such liquors appearing to act upon the principle of
displacement, and are charged with the tannic acid, and thus tanned as rapidly
or nearly so as the outer surfaces. It is a well-established fact, that liquids of
different densities have a strong tendency to mix with and diffuse themselves
through each other, and by reason of this tendency there is, so to speak, a
continued current or movement of the different liquids through the skin,
thereby not only tanning the inner parts of the skin as fast or nearly so as the
outer surfaces, but also rendering more rapid the whole process or operation of
tanning, and making it more complete and perfect.
By this improved process of tanning substantially as above described, I
thus prepare the skins by the use of the saline solutions, so that they will the
quickest and most completely receive the tannic acid, and by the use of weaker
and afterwards stronger and stronger tannic liquors, I hasten the process of
tanning, and also cause the process to take place in the inner parts as fast or
nearly so as in the outer surfaces.
If more convenient, or for any reason preferred, the skins may be saturated
in the saline solution without the presence of any tannic substance in the
commencement of the process; but it is deemed more expeditious to have the
tannic substance mingled with the saline solutions. The particular ratio or
proportionate increase in the strength of the tannic material is not fixed in any
exact scale, as this will vary according to and should be somewhat regulated
by the capacity of the skins to receive the tannic element.

page_text: What I claim as my Invention, and desire to have protected by Letters
Patent, is, tanning leather by the use of tannic liquors of different and
increasing strengths, in connection or combination with saline solutions, as set
forth, for the purpose of expediting the whole process, and tanning the inner
parts of the skin as fast or nearly so as the outer surfaces.
In witness whereof, I, the said Andrew Dietz, have hereunto set my hand
and seal. this Fifteenth day of March 1861.
ANDREW DIETZ. (L.S.)