AN IMPROVED PROCESS FOR TREating and SEPARATING THE HAIR OR WOOL FROM HIDES AND SKINS, AND FOR PRESERVING THE SAME WITHOUT INJURY TO THE HIDES AND SKINS
Year: 1875

page_text: LETTERS PATENT to William Harpham, Thomas Craven Harpham,
(Chemist), and William Thomson (Mechanical Engineer), all of
Leeds, in the County of York, for the Invention of "AN IMPROVED
PROCESS FOR TREating and SEPARATING THE HAIR OR WOOL FROM HIDES
AND SKINS, AND FOR PRESERVING THE SAME WITHOUT INJURY TO THE HIDES
AND SKINS."
Sealed the 20th December 1875, and dated the 10th September 1875.
PROVISIONAL SPECIFICATION left by the said William Harpham,
Thomas Craven Harpham, and William Thomson at the Office of
the Commissioners of Patents, with their Petition, on the 10th
· September 1875.
We, WILLIAM HARPHAM, THOMAS CRAVEN HARPHAM (Chemist), and
WILLIAM THOMSON (Mechanical Engineer), all of Leeds, in the County.
of York, do hereby declare the nature of the said Invention for "ẠN
IMPROVED PROCESS FOR TREATING AND SEPARATING THE HAIR OR WOOL FROM
HIDES AND SKINS, AND FOR PRESERVING THE SAME WITHOUT INJURY TO THE HIDES*
AND SKINS," to be as follows:—
This Invention relates to an improved process to be employed .in.

page_text: least from eight to fourteen days; the process is simple and certain,
and does not involve any departure from the present system or mode of
using the tan pits, excepting that a lesser number of pits will be
required where this Invention is put in practice. Another and valuable
result is that the hides and skins are much improved, and also heavier
when tanned; and further, that the action of the chemical compound
used is the same in all temperatures, whereas the ordinary lime process
varies considerably.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Harpham, Thomas Craven Harpham,
and William Thomson in the Great Seal Patent Office on the
8th March 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
HARPHAM, THOMAS CRAVEN HARPHAM (Chemist), and WILLIAM
THOMSON (Mechanical Engineer), all of Leeds, in the County of York,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of September, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said William Harpham, Thomas Craven
Harpham, and William Thomson, Her special licence, that we, the said
William Harpham, Thomas Craven Harpham, and William Thomson,
our exccutors, administrators, and assigns, or such others as we, the
said William Harpham, Thomas Craven Harpham, and William Thom-
son, our executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after 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. In-
vention for "AN IMPROVED PROCESS FOR TREATING AND SEPARATING THE HAIR
OR WOOL FROM HIDES AND SKINS, AND FOR PRESERVING THE SAME WITHOUT
INJURY TO THE HIDES AND SKINS," upon the condition (amongst others)
that we, the said William Harpham, Thomas Craven Harpham, and
William Thomson, our executors or administrators, by an instrument
-

page_text: -
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 we, the said William .Harpham, Thomas
Craven Harpham, and William Thomson, do hereby declare the naturo
of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the
.following statement in writing, that is to say :-
This Invention relates to an improved process to be employed in
treating and in separating the hair or wool from all kinds of hides
and skins, and for preserving the same without injury to the hides
or skins...
Such being the nature and object of our said Invention, we will
now proceed to describe more in detail the manner in which the same
is to be or may be performed or carried into practical effect.
The Invention consists in effecting the separation of the hair or wool
from the hides or skins by treating the same with an inexpensively
*prepared chemical compound which we term "sodic potassic sulphide,"
and which we compound or manufacture of or from salt cake, nitre
cake, carbon, and sulphur, the two former being refuse of or obtained
from the manufacture of sulphuric acid, and containing respectively
soda sulphate and acid sulphate of potash by taking, say, two parts 2
of the salt cake or sulphate of soda, one part of the nitre cake or acid
-sulphate-of-potash-and-two-parts of carbon, and breaking up, grinding;--|
and intimately mixing such ingredients, and then heating them in or
passing them through a reverberatory furnace, at which time or pre-
viously we add thereto a small proportion of sulphur, about four ounces
to a ton of the compound, which assists in the heating and helps to
"liquefy the compound as it passes through the furnace. The said
sulphate of soda and acid sulphate of potash contain a small proportion
of oxygen which is neutralized by or combines with the carbon, and
forms carbonic acid gas which passes off through the flue. The carbon
is used for this purpose and to combine the said sulphate of soda and
4

page_text: acid sulphate of potash, which having thus passed through the furnace
result in the improved depilatory or unhairing agent.
The carbon we use may be coal or a refuse which is obtained from
the manufacture of prussiate of potash, and which consists simply of
carbon.
The improved depilatory is inexpensive in its preparation or manu-
facture, and can be sold at a moderate cost.
The course of procedure in effecting the object of this Invention by
the use of the improved depilatory is as follows:-The unhairing pit
is first about one quarter filled with water to which a very small
quantity of lime in added in the proportion of about one quarter of a
bushel to two thousand gallons of water, which an ordinary pit usually
contains. The "sodic potassic sulphide" is then placed in the water
in the pit to dissolve, and the pit is subsequently nearly filled up
with water, which reduces the strength of the liquid depilatory to
about twenty per cent.; the hides or skins are then thrown into the
pit and turned over and about and stirred round in the same manner
as in the ordinary lime process. The object of the Invention will
then be obtained in from about five to about forty-eight hours,
according to the size and nature of the hides or skins, and the strength
of the liquid depilatory, the treatment of the hides or skins with which
will tend to improve the grain thereof, and add to their toughness, and
increase their weight when tanned and curried.
When the hair is intended to be preserved, as in the case of calf skins,
a weaker solution of the sodic potassic sulphide is used, say, of about
eight per cent.
In order to separate wool from skins the fleshy side is covered or
rubbed with a solution of the sodic potassic sulphide, and a very small
quantity of lime of about the same strength as used for calf skins; this
quickly penetrates the skin and allows the wool to be removed in about
two to three hours.
The following are the most material advantages derived from the
adoption of the above-described treatment of hides or skins with the im-
proved depilatory :-Its application will not interfere with the ordinary
process of tanning, but will simply depilate or unhair the hides or skins,
and it will effect a great saving of time, labor, and expense, as the

page_text: ordinary process of unhairing occupies from about eight to about
fourteen days; it is simple and certain and constant in action, and
in varying temperatues, whereas the ordinary lime process varies con-
siderably, and does not involve any departure from the present system
or mode of using the pits, a considerably. less number of which however
will be required; it greatly improves the hides and skins, and renders
them heavier and tougher when tanned and curried; it also allows
of the subsequent "baiting" of the hides being effected in a less time
than is sufficient after the usual depilating process; and further, after
having separated the wool from the sheep skins the liquid compound
may be used for feeding the skins, it having the effect of swelling.
and improving them considerably.
Having now particularly described and ascertained the nature and
object of our said Invention, together with the manner in which the
same is to be or may be performed or carried into practical effect, we
would remark in conclusion that we claim as our Invention, the
manufacture of the above-described composition forming the improved
depilatory or chemical compound which we term "sodic potassic
sulphide," and the application and use thereof in or to the treatment
of hides and skins for effecting the separation of the hair or wool
therefrom without injury thereto, substantially as herein described or
specified.
In witness whereof, I, the said William Harpham, on behalf
of myself and of the said Thomas Craven Harpham and William
Thomson,-have-hereunto set my hand, and seal, this Seventh
day of March, in the year-of our Lord One thousand eight