Improvements in and relating to the Manufacture of Leather.
Year: 1896

page_text: Date of Application, 7th July, 1896-Accepted, 29th Aug., 1896
COMPLETE SPECIFICATION.
Improvements in and relating to the Manufacture of Leather.
I, FRED ELISHA BURLINGAME, of No. 831 High Street, in the City of
Central Falls, County of Providence, State of Rhode Island, United States of
America, Chemist, do hereby declare the nature of this invention, and in what
nanuer the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention has reference to an improvement in the art of converting hides
and skins into leather by arresting the putrefaction of the gelatine in the skins or
hides in practically the same old and time-honored practice of immersing the hides
or skins in a tanning solution.
After a series of practical experiments with hides and skins of various animals
and of greatly varying thickness and other qualities, I have ascertained that the
condensed products of the destructive distillation of wood, or woody substances,
such as acorn-cup, the shells of cocoanuts and other similar woody-fiber, contain
valuable tanning properties and are useful in the tanning of hides and skins.
I have prepared tanning-liquor by mixing the crude product of the distillation
of wood, as it comes from the still, with chloride of sodium (common salt). I have
usually dissolved the salt in water and then added the water to the crude product
of destructive distillation in about equal quantities, that is to say, a gallon of the
salt water to each gallon of the wood-distillate; these I preferably agitate until
they are thoroughly mixed, when the liquor assumes a dark murky appearance.
I have also prepared the tanning liquor by mixing the crude pyroligneous acid
of commerce with water in which common salt (chloride of sodium) has been
dissolved in varying proportions, and, while I find that a liquor composed of
fifty per cent. of pyroligneons acid and fifty per cent. of water in which ten per cent.
of common salt has been dissolved answers well for the tauning of hides, I also find
that the crude product of distillation of the wood, containing the pyroligneous acid,
creosote, resinous matter and oily products, when about ten per cent. of chloride of
sodium (common salt) is dissolved in the same, will produce a more active tanning
liquor.
I find that alkalies, the alkaline earths, the salt of alkalies and the salts of
alkaline earths produce, when mixed with the crude product of destructive
distillation of wood-fiber or with pyroligneous acid, a tanning liquor having
practically the same qualities as when mixed with salt. For convenience and
economical reasons 1 prefer the use of common salt, but I do not wish to confine
myself to its use in the preparation of the tanning liquor, or to the proportions
hereinbefore described, as I find that these may be greatly varied.
The improved tanning liquor may be added to tanning-liquor containing tan-
bark, sumach, or other tanning agents and thereby the time required to tan a hide
reduced.
The so-prepared tanning-liquor is preferably placed into a suitable tanning vat
and the prepared hide ready for tanning is placed into the liquor until it has
sufficiently penetrated the hide or skin, which is then withdrawn from the liquor
and hung up to dry. When partly dry I immerse the hide in a saturated, or
nearly saturated, solution of chloride of sodium (common salt) and water and then
wash the hide in water, preferably running water.
The length of time during which the hide requires to be immersed in the tanning

page_text: liquor depends on the thickness of the hide and the nature of the tanning required,
for light hides, or heavier hides-requiring to be only surface tanned, less time is
required than for thoroughly tanned thick hides. In practice I find that one day,
or even less, is sufficient for very light hides and that ten days is sufficient to
produce heavy sole leather.
The time required for the immersion of the hide in the solution of salt and water
depends on the thickness of the hide, in practice I find that it may extend from one
to ten hours.
The hide or skin so tanned or converted into leather is finished in the usual
manner now used to finish different kinds of leather.
The leather so produced withstands the ordinary exposure to water better than
leather tanned in the older manner; it remains more pliable and appears to be less
affected by the water. The leather produced is denser, stronger and more durable
than leather heretofore produced, it appears to retain more of the strength of the
raw hide, while the preservation of the gelatine and the tissues is more perfect.
The leather is readily recognized from other leather by its odor, and can be
distinguished by the usual chemical tests for creosote, resinous matter and tarry
products.
I find, in practice, that when a hide is immersed in pyroligneous acid, the acid
will continue to act on the skin or hide and produce a hard, woody substance, but
not leather, and that when chloride of sodium, an alkali, alkaline earths, the salts
of alkalies, or the salts of alkaline earths, are mixed with the pyroligneous acid,
this acid acquires tanning properties and acts on the skius or hides like tannic acid
and produces good leather.
Many other substances will, no doubt, combine with the pyroligneous acid and
the crude products of the destructive distillation of wood or woody substances and
produce the same or similar results, I do not, therefore, wish to confine myself to
chloride of sodium or the substances I have found to act in a like manner, as it is
evident that many other agents will be found that will produce practically the
same result.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
Claim 1. A tanning liquor containing the product of destructive distillation of
wood-fiber and chloride of sodium or similar substance, substantially as described.
2. A tanning liquor consisting of pyroligneous acid, water and chloride of sodium
in the proportions substantially as described.
3. A tanning liquor containing pyroligneous acid and chloride of sodium or
similar agent, substantially as described.
4. The process herein described for converting hides into leather, the same
consisting in immersing the hide in a bath containing the liquid product of
destructive distillation of wood and salt or similar agent, partially drying the hide,
then immersing the same in a bath of salt and water, and washing and drying the
leather, as described.
5. The step in the process of converting hides into leather, the same consisting
in immersing the hide in a bath containing pyroligneous acid and chloride of
sodium or other similar agent, as described.
6. The step in the process of converting hides into leather, the same consisting
in immersing the hide in a bath consisting approximately of one part pyroligneous
acid, one part of water, and common salt, as described.
7. As a new article of manufacture, leather the tissues and gelatinous matter of
which contain the products of the destructive distillation of wood combined with
chloride of sodium or similar agent, as described.
8. The new article of manufacture and commerce, consisting of leather the
tissues and gelatinous matter of which is combined with pyroligneous acid and salt,
as described.

page_text: 9. A leather having the usual characteristics of tanned leather in the
production of which pyroligneous acid has combined with the hide or skin, as
described.
Dated this 23rd day of May. A.D. 1896.
In presence of
JOSEPH A. MILLER, Jr.
FRED ELISHA BURLINGAME.
Haseltine, Lake & Co.,
45 Southampton Buildings, W.C., Agents for the Applicant.