A METHOD OF TANNING HIDES AND SKINS
Year: 1794

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, SAMUEL
ASHTON, of Sheffield, in the County of York, Painter, send greeting.
WHEREAS His most Excellent Majesty King George the Third, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Sixteenth day of January, in the thirty-fourth year of His reign,
did give and grant unto me, the said Samuel Ashton, His special licence,
that I, the said Samuel Ashton, 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 OF
TANNING HIDES AND SKINS;" in which said Letters Patent there is contained a
proviso obliging me, the said Samuel Ashton, 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).
NOW KNOW YE, that in compliance with the said proviso, I, the said
Samuel Ashton, do hereby declare that my said Invention of A Method of
Tanning Hides and Skins is described in manner following (that is to say) :-
By the method of tanning which I have invented bides and skins are com-
pleately tanned into leather of an excellent quality, without the assistance of
bark, in much less time and at considerably less expence than by any other
method hitherto known or practised. The following is a general description
of the materials to be used as ingredients in preparing the tan liquor mado

page_text: use of in my process of tanning berein-after described (that is to say):-Iron,
either in its metallic or calciform state, or dissolved or mineralized with
sulphur, or mixed with sulphur and clay, sulphurated arsenic, vitriolic acid, or
phlogiston, or with any other sulphurated or arsenical metal or metals; copper,
either in its metalic or calciform state, or dissolved or mineralized with
sulphur, sulphurated iron, or sulphur, iron, and arsenic, or dissolved by vitriolic
acid or with phlogiston, or mixed with any other sulphurated or arsenical
metal or metals; zinc, in its metallic state or calciform, mixed with martial
ochre, or mineralized with sulphurated iron, or by sulphur, arsenic, and iron,
or by vitriolic acid, mineral phlogiston, or bitumen, united with vitriolic acid,
or saturated with iron, or combined with iron, iron and copper, iron and zinc,
iron and arsenic, or copper, and generally all metal, metallic or metalline sub-
stances, fossils, ores, cales, carths, sands, clays, and stones, whose astringent
bases are saturated with or principally composed of all or any of the above-
described substances or matters, or that are therewith impregnated or com-
bined in such degree or proportion as not to be neutralized, or that are
properly denominated astringent, sulphurious, sulphurated, vitriolic, vitriolated,
arsenical, martial, ferruginous, or cupreous; and all mineral waters impreg-
nated in a sufficient degree with all or any of the above-described substances
or matters; and all preparations made of or from the said described substances
or matters or mineral waters wherein their respective astringent, sulphureous,
sulphurated, vitriolic, vitriolated, arsenical, martial, ferrugenous, or cupreous
virtues, qualities, or particles are preserved, and not destroyed or neutralized.
The following materials are particularized from the above in order to elucidate
the process and proper method of preparing the said tan liquor; namely, iron,
native iron, the rust of iron, minera ochracea or martial ochre, ochra ferri, bog
ore, blood stone or hæmatites ferrnum, sulphure saturatum, or marcasite, black
iron ore, or iron stone, the pyrite, sulphureous stone, the arsenical pyrites,
martial, martial coal ore, copper, native copper, ochren veneris, grey or vituous
copper ore, yellow or marcasiteral copper ore, white copper ore, vitriol of
copper, copper coal ore, zinc, native zinc, calamine zinc ore, blinde, vitriol of
zinc, sulphur or brimstone, native sulphur, pale yellow pyrites, liver-coloured
marcasite, the sulphurcous coal, the bovey coal, alum, slate, and peat. Tho
following preparations and proportions illustrate to what degree of strength or
astringency the solution for tan liquor is to be made, and also which of the
above particularized materials are proper to be used therein separately, and
which of them ought to be used together, and consequently which of the abovo
generally described materials are proper to be used separately, and which of
them ought to be used together, in the preparation of the tan liquor. To

page_text: sixteen pounds of scales or rust of iron, saturated with six ounces of oil of
vitriol, and one quart of water, mix six gallons of common water; to sixteen
pounds of iron ore, calcined and reduced to powder, mix six gallons of
common water; to twelve pounds of sulphur stone or pyrite sulphurcous stone,
calcined, mix six gallons of common water; to sixteen pounds of the ferrugenous
yellow earth or red ochre, calcined, mix six gallons of common water; to six-
teen pounds of the same yellow earth, in its raw state, mix six gallons of
water and six ounces of oil of vitriol; to fourteen pounds of good copper ore,
calcined and reduced to powder, mix six gallons of water; to sixteen pounds
of ochrea veneris, or carth impregnated with copper or copper ore, calcined,
mix six gallons of water; to eight pounds of sulphur stone and six pounds of
native or calamine zinc, calcined and reduced to powder, mix six gallons of
water; to twelve pounds of red ochre and six pounds of native zinc or cala-
mine, calcined and reducer to powder, mix six gallons of water; to eight
pounds of sulphur stone or pyrite, and four pounds of native sulphur, calcined
and reduced to powder, mix six gallons of water; to twelve pounds of red
ochre, and four pounds of native sulphur, calcined and reduced to powder,
mix six gallons of water. In general the waters issuing out of or from coal pits,
or the mines or places where coal, iron, or copper ores abound, when boiled for
two hours are of a sufficient degree of astringency. With regard to the most
proper and leading materials, being the best calculated for common practice
on account of their very great abundance and cheapness, are the dross of coal
pits, called sulphur stone or pyrite sulphureous stone, and the yellow ferru-
genous earth or red ochre, both above described; and they will have the pre-
ferrence in all parts where such substances abound the most, or to such places
where they are the most contiguous, and perhaps in Wales and other places
where the ores of copper and other astringent, sulphureous, vitriolic, or vitrio-
Jated substances, as described above, do most abound, these may claim the
preferrence. But of these matters every person who follows the business of
tanning will best judge for himself. It is necessary to observe, that the above
preparations and proportions are specified upon the supposition that the various
materials therein mentioned respectively contain the utmost degree of strength
or astringency which they in general possess; but as the same are variable,
according to circumstances, with respect to the degree of strength or astrin-
gency they respectively possess, the strength of the tan liquor must ultimately,
in all cases, be determined by the taste, which should be rought or austere,
whereby, and by the assistance of the above-mentioned preparations and pro-
portions, the proper degree of strength or astringency of the tan liquor may be
always known with sufficient certainty.

page_text: The process of tanning the thickest and best hides, usually termed sole
leather, is as follows:-After the operation of taking off the horns, scraping off
the hair, paring away the loose flesh, and working out the fat or grense is
finished, which may be done in the common method, the hides are to be taken
to a vat in which is prepared the tan liquor agreeably to any of the directions
above set forth, in which they are to be laid smooth, and to be turned twice
every twenty-four hours for the space of seven or eight days, and once every
twenty-four hours for the space of five weeks afterwards, according to the
number, weight, and thickness of the hides, at the same time stirring up the
tan liquor sufficiently, after which they are to remain till they are sufficiently
tanned, which will in general be from five to seven or eight weeks, according
to the quality of the tan liquor, and the number and substance of the hides.
It should be observed, that if the tan liquor is too strong when the hiles are
first laid therein there is a danger of its corrugating or drawing up too close
the outside parts thereof, which will prevent the operation of tanning from
going on in a regular and proper state, and in some degree injure the leather;
but, in order to guard against this, it is proper to make the tan liquor weaker
when the hides are first put into the vats, and to make it stronger by degrees
by adding thereto, every three or four days, a quantity of the materials where-
with it is prepared for three or four weeks, so as in that time the whole pro-
portion thereof may be put into the vat. In case it should be suspected that
the hides are injured by too great strength of the tan liquor it will be proper
to immerse them for about half an hour in a solution of lime or potash in
water or in any other alkali solution. When the metallic substances froni
which the tan liquor is prepared are calcined, it is not necessary to add
thereto the vitriolic or sulphuric acid, except when great expedition is
required; but when these substances are used in their raw state, the vitriolic
or sulphuric acid in some degreo answers the purpose of calcination. In those
cases where the acid is used it is most proper to omit adding it to the tan
liquor till the hides have lain therein one week.
'
The process of tanning the inferior sortment of hides intended for crop
leather, and of calves' skins, is as follows:-When tho hides and skins aro
prepared for the tan vat in the usual way, they are to be taken to a vat-in
which is prepared the tan liquor according to some one of the directions above
mentioned, and reduced to a proper strength and quality by mixing therewith
white clay, chalk, whiting, or other pure calcareous earth, and to be turned
every six hours for the space of four days, according to the number and sub-
stance of the hides and skins, after which they are to remain until sufficiently
tanned, which will in general be from eighteen to twenty-eight days.

page_text: In the above-described processes of tanning, barks or other vegetable sub-
stances are not at all essential; nevertheless, when the colour of the leather is
an object to be attended to, the bark of oak and many other barks, and several
kindos of woods and vegetables, are useful as a dye for rendering the colour
such as is commonly acquired by leather tanned with bark; and, for this
purpose, a small quantity of oak bark or logwood, put into the vat with the
tan liquor, is sufficient.
After the hides or skins are tanned, the proccess of getting them ready for
sale is to be pursued in the common way.
In witness whereof, I, the said Samuel Ashton, have hereunto set my
hand and seal, this Fourteenth day of February, in the thirty-fourth
year of the reign of His said Majesty, and in the year of our Lord
One thousand seven hundred and ninety-four.
SAMUEL (L.S.) ASHTON.
Signed, scaled, and delivered in tho
presence of
JOHN DOUBLEDAY.