IMPROVEMENTS IN TREATING HIDES AND SKINS
Year: 1861

page_text: LETTERS PATENT to Henry Constantino Jennings, of Great Tower Street,
in the City of London, Chemist, for the Invention of "IMPROVEMENTS IN
TREATING HIDES AND SKINS."
Sealed the 31st January 1862, and dated the 14th September 1861.
PROVISIONAL SPECIFICATION left by the said Henry Constantine
Jennings at the Office of the Commissioners of Patents, with his Petition,
on the 14th September 1861..
I, HENRY CONSTANTINE JENNINGS, of Great Tower Street, in the City of
London, Chemist, do hereby declare the nature of the Invention for "IMPROVE-
MENTS IN TREATING HIDES AND SKINS," to be as follows:-
I
This process is based upon the chemical conversion of the gelatine contained
in hides and skins to render it insoluble, thus producing a similar result to
that obtained by tanning, and by other processes now practised by tanners.
subject hides and skins after being deprived of hair and offal to a saturated
solution of carbonate of soda or of potassa at the common atmospheric tem-
perature, in which solution they are to be steeped or immersed during six
hours, taking care that each hide or skin shall be separated from the other
by wicker hurdles or otherwise. After the expiration of about six hours the
hides and skins are to be removed and drained, and then immersed in a
saturated solution of sulphate of alumina or alum, to which is added about two
per cent. of sulphuric acid of commerce, and two per cent. of hydrochloric

page_text: acid. The hides or skins are to be left in this second solution for about six
hours, and after that time are to be transferred again to the first or alkaline
solution; these alternate changes from a neutral alkaline solution to that of an
acid aluminous solution will in a few days change the whole of the gelatino
into an insoluble substance of great strength and elasticity. The duration of
these operations will depend upon the thickness and quality of the skins to be
operated upon. When the complete saturation and transformation of the
gelatine is effected, the hides and skins are to be taken from the tanks and air
dried, after which they are to be steeped for about 12 hours in a saturated
solution of alum, to which is to be added ten pounds (per centum) of tunstato
of soda; this solution is to be kept at a temperature of about 100° Fahrenheit.
The skins and hides are now to be plunged into a solution of soft or potassa
soap, or of mottled or resinous soaps, according to circumstances, the solution
containing 15 per cent. of soap to 85 per cent. of water, and being used at a
temperature of about 100°, especially in cold weather. The skins remain 24 to
86 hours in this solution, being frequently moved and pressed therein to effect
the entrance of the saponaceous fluid, so as to cause it to combine with and
decompose tho saline substances last employed; the skins are now to be well
washed, and then rolled to express or remove the superfluous liquid matter,
and also to condense the substance of the skins, and render them even and
uniform.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Constantine Jennings in the Great Seal Patent Office
on the 14th March 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
CONSTANTINE JENNINGS, of Great Tower Street, in the City of London,
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of September, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
suid Henry Constantine Jennings, Her special, licence that I, the said Henry
Constantine Jennings, my executors, administrators, and assigns, or such others
as I, the said Henry Constantine Jennings, 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

page_text: lawfully might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Inven-
tion for "IMPROVEMENTS IN TREATING HIDES AND SKINS," upon the condition
(amongst others) that 1, the said Henry Constantine Jennings, 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 Henry Constantine Jennings, 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 thereof, that is to say:-
For preparing butts or ox hides of great thickness and weight, the hair,
should be removed by a solution of caustic lime in the usual manner, but after
the hair and offal parts are separated the skin or felt should be again returned
into the lime pit for 24 hours, then removed and washed in water containing
on or about two pounds per cent. of hydrochloric acid, for the purpose of, dis-
solving or discharging the lime that may be contained in the skin; and to
open the same the skins are now to be laid horizontally and evenly upon the
bottom of a perforated case or frame, which frame is to be fitted with a strong
iron brace or handle, sufficient to bear the weight of ten or a dozen ox hides,
or about 1,500 lbs. with a loop or ring in the centre, by which to lift it in and
out of the pits or tanks every six or more hours, as required. Between each
skin or hide should be placed a wicker hurdle, so as to separate each skin
from the other, by which the liquor or solutions employed will be enabled to
penetrate freely and equally into each skin; there should be two of such cases
or frames. Two pits or tanks are to be provided somewhat larger and deeper
than the frames; these pits I number 1 and 2. No. 1 is charged with a
solution of sulphate of alumine or alum of commerce saturated at the atmo-
spheric temperature; to this solution is added two pounds per centum of
sulphuric acid, and two pounds per centum of hydrochloric acid. Pit or tank
No. 2 is charged with a solution of carbonate of soda or soda ashes saturated
at the atmospheric temperature, and to this it is preferred to add five pounds
per centum of dry tungstate of soda. The frames charged with skins are
lowered into the pits by any convenient tackle, and left therein during six
hours, taking care that the solutions in each pit contain enough liquor or solu-
tion to cover the uppermost skin in each frame. After the skins have remained

page_text: six hours in the pits they should be raised out of the liquor, and allowed to
drain each over the pit in which it has been immersed. When all the free
liquid or solution has drained off, the frames are to be moved and transferred:
into the opposite pit or solution, so that the skins shall alternately be exposed
to the decomposing action of solutions, one acid, the other alkaline. Each
frame is to remain six hours in the solutions, and to be drained at overy
change that is made. When the skins are saturated it will be readily seen by
cutting the edge of the thickest part of a skin, if the inner part or centro
remains transparent and glossy instead of opaque and fibrous, it is evident
that the gelatine of the skin is not converted into insoluble fibrous matter to
the centre, the firmness and closeness of the skin when perfectly prepared and
saturated will be evident both to the eye and touch. The duration of the
process will entirely depend upon the thickness of the skins operated upon;
those of a full-grown ox will require a longer time than the skins of smaller.
animals, and in winter the temperature should be kept to about 100° Fah-
renheit. When perfect saturation has been obtained, and the whole of the.
gelatine has become fibrous and insoluble, the skins are drained and then put
into a solution of tungstate of soda, made by saturating soft water with that
salt at the atmospheric temperature. The skins are, when saturated with the
tungstate solution, to be placed in a solution of soap, containing from 15 to
20 lbs. of soap to 100 lbs. of soft water, thoroughly dissolved and mixed. The
skins should be turned over and agitated in the solution of soap until the
whole of the soap is absorbed into them, and the water becomes clear and
limpid; the skins are now left 24 hours in fresh water to remove all extra-
neous salts and give brightness to the goods. It will now be of some advan-
tage to steep the skins, as above prepared, in a solution of twig or coppico
oak bark during 24 hours to impart the color and odour of common tanned
leather; this object is best effected by hydraulic pressure to ensure the com-
plete penetration of the tannic acid solution. The preparation of the lighter
and finer skins by this process will require modifications both as to the force
and proportions of the chemical solutions, and the duration of the skins in
each solution, which should vary according to the use and application of the
leather, especially if not required to be rendered hydrofuge, in that case the
solution of soap has only to be omitted. Butts, kips, or strong hides des-
tined for the fabrication of boots and shoes should be passed between cylinders
or rollers when in a damp state to level the surface of the flesh sido of the
skin, and also to produce that equal degree of condensation of the fibres which
renders the wear and tear of the substance more uniform, and by expelling all
the free water and salts greatly facilitates the drying and improves the appear-

page_text: ance of the goods. Lastly, it is advantageous for some kind of goods to apply
a small portion of vegetable or animal oil to the grain surface of the skins to
render the leather flexible, strong, elastic, and bright, but this dressing is more
in the department of the currier, except that too large a dose of oil is inap-
propriate for skins prepared by this process. When very thin and light skins
are prepared, and color is of importance, it is advantageous to add on or about
5 lbs. per cent. of filings of zinc to pit or tank No. 1 (the acid solution), the
metal dissolves and the zinc salts that are formed will impart extreme
whiteness to the goods, particularly to the skins of kids, lambs, &c., and to
such skins as are destined for glove purposes.
Although these processes are entirely distinct from the old modes of
tanning, inasmuch as I use only inorganic elements and mineral acids (since
the solutions of oak bark I employ are merely to impart color and odour), it
will be in the power of the ordinary tanner to give a much better effect and
produce more perfect results than can be obtained by any workman not prac-
tically conversant with the business, as the tanner will quickly perceive when
the goods have reached a proper degree of solidity, insolubility, and elasticity.
If a great degree of hardness and density is required for pump leathers, soles
of shoes or boots, or other purposes, the proportions of sulphate of alumine
should be increased beyond the degrees above specified, and the solution of pit
or tank No. 2 should be further diluted, or in other words, should contain less
carbonated alkali, and the skins should remain in that solution only half the
time, or 2 or 3 hours in lieu of 6 hours, as above stated, when the framo
should be transferred to pit or tank No. 1 containing the acid solution.
In witness whereof, I, the said Henry Constantine Jennings, have here-
unto set my hand and seal, this Thirteenth day of March, in the
year of our Lord One thousand eight hundred and sixty-two.