A METHOD OR PROCESS, COMMUNICATED TO ME BY A CERTAIN LEARNED FOREIGNER WITH WHOM I AM CONNECTED, OF TANNING ALL SORTS OF HIDES AND SKINS, AND OF RENDERING MORE SOLID AND INCORRUPTIBLE IN WATER SEVERAL VEGETABLE AND ANIMAL SUBSTANCES, SUCH AS FLAX, HEMP, SPARTERY, COTTON, SILK, HAIE, WOOL, &c, AS WELL AS THE MATERIALS MADE THEREOF
Year: 1796

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
DESMOND, of Shepherd Street, Hanover Square, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Fifteenth day of January, in the thirty-sixth year of His
reign, give and grant unto me, the said William Desmond, His especial
licence that I, the said William Desmond, during the term of years therein
mentioned, should and lawfully might use, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, my Invention of "A METHOD OR
PROCESS, COMMUNICATED TO ME BY A CERTAIN LEARNED FOREIGNER WITH WHOM I AM
CONNECTED, OF TANNING ALL SORTS OF HIDES AND SKINS, AND OF RENDERING MORE
SOLID AND INCORRUPTIBLE IN WATER SEVERAL VEGETABLE AND ANIMAL SUBSTANCES,
SUCH AS FLAX, HEMP, SPARTERY, COTTON, SILK, HAIE, WOOL, &c, AS WELL AS THE
MATERIALS MADE THEREOF;" in which said Letters Patent there is contained a
proviso, obliging me, the said William Desmond, by an instrument in writing'
under my hand and seal, to cause a particular description of the nature of my
said Invention, and in what manner the same is to be performed, to be inrolled"
in His Majesty's High Court of Chancery within one calendar month after the
date of the said recited Letters Patent, as in and by the same, relation' being
thereunto had, may more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
William Desmond, do hereby declare that my said Invention is described in
manner following (that is to say):-
As that part of the preparation of hides and skins properly called tanning
consists in impregnating and saturating them with a principle obtained from
tan, by which they acquire strength and firmness, preserve a suflicient flexibility,
and become indissoluble and incorruptible in water, either hot or cold, so the
nature of this process is 1st, to ascertain by a simple and certain criterion such
substances as contain the said principle; 2d, to extract it from them, to seperate
it from every other principle by which its effect may be impeded or counter-
acted, and to give it the degree of strength necessary for the intended purpose;
3, to dispose the hides and skins for the introduction of this principle; 4th,
to imprognate and saturate them compleatly with the same in less than a teuth
part of the time usually employed in tanning, all which operations are per-
formed in the following manner:-Provide five vessels, called digesters, of
any convenient, materials and dimensions, with an aperture at the bottom
of each, let them be placed near each other, and elevated upon stillages
or otherwise, so that a pail or other smaller vessel may be placed under
them. Fill the digesters with tan, that is to say, with the bark of certain
.trees, of oak for instance, cut small or ground to a coarse powder; pour water
on the tan in the first digester, where it may stand some time or be drawn off
immediately. This liquor is to be poured on the tan in the second digester
and drawn off as before, then on the tan in the third digester, and so on untill
it comes through the tan in the fifth and last. The liquor is then highly
coloured and marks from six to eight degrees on the hydrometer for salts.
This liquor is to be used for tanning the thickest hides, and may, for want
of a moro characteristic name. be called the tanning lixivium; it has this
peculiar property, that if you take a small quantity of it in a glass, and
pour on it a few drops of a solution of animal glue, the liquor, which before
was clear, becomes turbid, and a whitish substance falls to the bottom of the
glass. The precipitate thus obtained by means of the solution of glue is a
sure indication that the liquor contains the tanning principle; for this reason,
that glue being of the same nature with the skins or hides of which it is inade
whatever substance unites itself indissolubly with the former will do so likewise
with the latter. This solution is made by dissolving a little common glue in
wator over a moderate fire; by means of it, not only oak bark, but also the bark
of several other trees, such as the plane tree, chesnut tree, the American hem-
lock tree, poplar, elm, willow, &c., as well as divers shrubs and plants, such

page_text: as myrtle, shumach, &c., all which I call tan, are found to contain the tanning
principle, and by employing the solution, as above, it will in all cases be easy to
ascertain whether any given substance contains this principle or not. In the
course of these lixiviations two things will be observed; 1st, the liquor runing
from the first digester at length looses its colour. If in this state you take a
little of it in a glass and repeat the former experiment, the liquor no longer
becomes turbid, but remains clear, which shews it contains no more of the tan-
ning principles; but if you pour into the same glass a few drops of sulphat
of iron the liquor becomes thick and black. This liquor is not to be poured
on the tan in the second digester, but is to be laid by and used for the de-
pilation or taking off the hair or wool, as will be more particularly described
hereafter. It is distinguished by the name of gallic lixivium, because it
appears to contain the same principles as galls. The sulphat of iron is
obtained by dissolving a small quantity of iron in oil of vitriol diluted with
water, or by dissolving green coperas in water. This solution serves to ascer-
tain such substances as contain the gallic principle; lime water will also produce
this effect. When the liquor ceases to grow black by the mixture of sulphat
of iron, it will be useless to pour any more water on the tan in the first
digester. This tan being exhausted both of the tanning and gallic principles
must be removed and new tan put in its place. You will observe, 2d, that the
liquor after running through all the digesters at last grows weak. Add to your
stock of tanning lixivium all the liquor that marks from six to eight degrees
on the hydrometer; what proceeds afterwards from the last digester is to be
poured on the new tan in the first; then the fresh water is to be conveyed on
the tan in the second digester, and the liquor of the first to be laid by while it
marks six or eight degrees on the hydrometer, and added to the tanning
lixivium which must always be carefully seperated from the gallic. In this
manner the tan in all the digesters may be renewed and the lixiviations con-
tinued. The numbers of these lixiviations, as well as the mode of making them,
may be varied at pleasure; the essential point is to repeat them, so as to give
the liquor a sufficient degree of concentration, which may be determined by
the bydrometer, and proportioned to the quickness required in the operation,
and to the thickness of the hides and skins to be tanned, all which experience
will soon teach. As all kinds of tan are not equally good, it will sometimes
happen that six or more filtrations will be necessary to obtain a lixivium
of six or eight degrees; in this case the number of digesters may be increased,
and the same method pursued as above, and when a weaker lixivium.
is wanted three or four filtrations will be sufficient. The person who directs
these lixiviations should be provided with a solution of glue and sulphat of

page_text: iron, already described, in order to ascertain the qualities of the different lixivia,
as well as with an hydrometer or areometer properly graduated to determine
their degree of concentration or specific gravity.
Cow HIDES, Ox HIDES, &c.
1st, washing and fleshing; they should be washed in running water, well
cleaned and fleshed in the usual way. 2d, depilation, or taking off the
hair; immerse the hides for two or three days in a vat filled with gallic
lixivium, and a mixture of sulphuric or vitriolic acid or oil, marking sixty-six
degrees on the hydrometer for acids, and in the proportion of one to a thousand,
that is, ono part of oil of vitriol to a thousand parts of gallic, or one pint to
125 gallons; during this immersion, the hair is detached from the hides in
such a manner that you may easily know when they are to be taken out of tho
vat, that is, when the hair is quite loose; it is then to be scraped off with tho
round knife on the horse. Srd, raising; when raising is necessary, which is
seldom if ever the case, immerse the hides for ten or twelve hours in another
vat filled with water, and a five-hundredth part of its volume of mineral acid of
the same quality as the former, and the operation of raising or swilling is done.
Wash the hides repeatedly and use the round knife, then are they fully pre-
pared for tanning. 5th, tanning; the remaining part of the process consists
in tanning properly so called, for which purpose, steep the hides for somo
hours in a weak tanning lixivium of only one or two degrees, to obtain which
you may take that which runs from the second digester, or some that has been
already used for tanning; they are then to be put into a stronger lixivium,
where in a few days they will be brought to the same degree of saturation with
the liquor in which they aro immersed. The strength of the liquor being then
considerably diminished, it must be renewed, and when the hides are com-
pleatly saturated, that is, fully tanned, which is known by cutting off a bit of
the edge, remove the leather, and let it dry slowly in a shady place.
CALF SKINS, GOAT SKINS, &c.
1st, flesh them with the knife, and work then in running water, like the
others; 2d, steep them in lime water, in which there should be more lime
than the water can dissolve at onco; what is not dissolved will subside to tho
bottom, but must be mixed with the water by stirring it several times a day;
3d, after two or three days remove the skins; when tho bair is found quito
loose, scrape it off on the horse, wash and press the skins well until the water
running from them is perfectly clear and the lime totally exhausted; 4th,
steep them first in a weak lixivium, then tan them as above; but observe that
Time in

page_text: used for these soft skins instead of the mixture of gallic lixivium and vitriolic
acid, for this reason, that acid always swells the leather more or less, which
would injure the skins, and because the lime may be more easily extracted
from them by washing and compressing them than from thick hides, which
when limed are harsh and apt to crack, if the lime is not totally extracted
before they are tanned.
Amongst the different modes of immersion which may be practised in the
course of these operations, the best appears to be that of suspending the hides
and skins vertically in the lixivia by means of transversal rods or bars, and at
such a distance as under as not to touch each other in any one point. If they
are laid out one over the other, according the common practice, they will
require frequent handling, in order that all the parts may be equally saturated,
and to prevent the folds or plaits that otherwise would be formed in them, and
all this would occasion a considerable loss of time and labour. In some cases it
will be found expedient.to mix fresh tan from time to time with the lixivium;
this and other modifications, such as the various strengths of the lixivium, the
raising or not raising the hides, the use of the gallic lixivium, &c, which may
be found necessary, will depend on the state and quality of the hides and skins
to be tanned, as well as on the purposes for which they are intended. All these
considerations must be left to the judgment of the manufacturer, but do not in
any way alter or change the principle on which the mode of tanning is founded.
Besides, the very great saving in point of time and labour, the leather tanned
according to the above method being more compleatly saturated, will be found
to weigh heavier, to wear better, and to be less susceptible of moisture than
the leather tanned in the usual way.
The other animal and vegetable substances already mentioned, by being
steeped for a certain time in a weaker or stronger tanning lixivium, according
to the difference of their contecture, will acquire strength and incorruptibility.
Cords, ropes, and cables made of hemp or spartery impregnated with this prin-
ciple will support much greater weights without breaking, will be less liable to
be worn out by friction, will run more smoothly on pullies, &c. This liquor,
in short, will be found so advantageous, particularly in the rigging of vessels,
as to render the use of tar in many cases unnecessary; even meat may be
preserved by it without salt.
In witness whereof, I, the said William Desmond, have hercunto set my
band and seal, this Fourteenth day of July, in the year of our Lord
One thousand seven hundred and ninety-six.
WILL" DESMOND. (L.s.)

page_text: AND BE IT REMEMBERED, that on the same Fourteenth day of July, in
the year above written, the aforesaid William Desmond came before our
Lord the King in His Chancery, and acknowledged the Specification aforesaid,
and all and every thing therein contained in form above written. And also the
Specification aforesaid was stamped according to the tenor of the Statute in
that case made and provided.
Inrolled the same Fourteecth day of July, in the year above written.