INVENTION, DISCOVERY, AND IMPROVEMENTS IN THE TANNING OF LEATHER BY THE USE OF PYROLIGNUS OR WOOD ACID
Year: 1812

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ANDREW
PATTEN, of Hulme, in the Parish of Manchester, in the County of Lancaster,
Iron Liquor Manufacturer, and CHARLES HANKINSON, of Hale, in the Parish
of Bowden, in the County of Chester, Tanner, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twentieth day of
January, in the fifty-second year of His reign, give and grant unto us, the
said Andrew Patten and Charles Hankinson, our exors, adñiors, and assigns,
His especial licence, full power, sole privilege and authority, that we, the said
Andrew Patten and Charles Hankinson, our exors, adññiors, and assigns, and
every of them, during the term of years therein mentioned, should and law-
fully might make, use, exercise, and vend, within England and Wales and the
Town of Berwick-upon-Tweed, our "INVENTION, DISCOVERY, AND IMPROVEMENTS
IN THE TANNING OF LEATHER BY THE USE OF PYROLIGNUS OR WOOD ACID;" in
which said Letters Patent there is contained a proviso, obliging us, the said
Andrew Patten and Charles Hankinson, or one of us, particularly to describe
and ascertain the nature of our said Invention, and in what manner the
same is to be performed, by an instrument in writing, under our hands and
seals, or under the hand and seal of one of us, and to cause the same to be
inrolled in His Majesty's High Court of Chancery within two calendar months
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, we, the said
Andrew Patten and Charles Hankinson, do hereby declare that the nature of

page_text: our said Invention or Improvement in the Tanning of Leather by the Use
of Pyralignus or Wood, and is used and perfected in the manner following
(that is to say) -
When the
The hides and skins intended to be tanned are to be first limed, haired,
fleshed, and beamed in the manner in general used by tanners.
hides or skins have been limed, haired, fleshed, and beamed in the manner in
general used by tanners, they are to be well washed and cleared of the lime
and masterings, and then immersed into a pit of weak ooze or liquor made
from oak bark, in which they must remain for five or six weeks, and be
handled well till they begin to bloom, then they are to be taken out and
immersed in a pit of pyrolignus or wood acid for ten or fourteen days, or for a
shorter or longer time, according to the substance of the hides or skins, taking
care to handle them well every day; but before the pyrolignus or wood acid
is put into the pit care must be taken to have the pyrolignus or wood acid
well filtered or cleared from all oily or tarry matter, in the manner after men-
tioned. If the hides or skins be light, the pyrolignus or wood acid should be
weakened or reduced by putting to it as much water or spent ooze liquor as
pyrolignus or wood acid, and if the hides or skins be very light there should be
put three times or four times as much water or spent ooze liquor as pyrolignus
or wood, and the quantities of water or spent ooze and pyrolignus or wood
acid must be regulated according to the strength of the hides or skins; and
the hides and skins should be handled well every day till sufficiently raised,
and then they should be immersed into a pit of clear water, and remain in it
one or two days, and be handled well each day. This may be done, or not, as
shall be convenient. Then, in order to bring the hides or skins as near as
possible to the colour which is generally given to leather, they should be
removed into a pit or pits of strong ooze or bark liquor, and be suffered to
remain there for three or four weeks, or they may be put into two lays of bark
in the usual way of tanning, and remain in each of such leys three or four
weeks, then they may be taken up and dried for sale; but if the hides be very
heavy it will be prudent to lett them lay a little longer time, both in the
pyrolignus or wood acid and in the bark liquor or ooze.
A second method of using the said Invention is, after the hides and skins
have been limed, haired, fleshed, and beamed, and washed and cleaned from
the lime and masterings, as herein-before mentioned, to take spent bark, or
spent fustick, or spent American bark, or spent shumac, such as has had its
strength drawn from it by the dyer, or any other use having been made of it,
or indeed any other kind of spent wood or ground wood or saw dust, so that
it be freed from any colouring quality which is it all likely to stain or injure

page_text: the leather, and put any one of them (in the same proportion as you would
take bark to make a strong ooze) into a pit, and mix them with pyrolignus or
wood, and into which immerse the hides or skins, taking care to handle them
well once each day. They must on each succeeding day be removed into a
pit of water, to which must be first added a proportion of the spent fustick, or
spent bark, ground wood, or any one of the articles mentioned in the.second
method, in the same proportion as that put to the pyrolignus or wood acid,
taking care to remove the hides or skins every other day out of one pit into
the other, and to stir well up the pit into which they shall be removed before
the hides or skins are put into it. This is to be continued to be done for six or
eight weeks, or for a longer or shorter time, according to the substance of the
hides or skins, until the hides or skins shall be sufficiently tanned. Light
skins will be very soon tanned upon this principle; but they must be .well
attended to. Fifteen or twenty gallons of the pyroliguns or wood acid put
into a pit of the weak ooze or spent bark liquor will renew it, and make it fit
for receiving fresh hides or skins. The pyrolignus or wood acid may be used
alone, without any other article being added to it or used with it, only
in the filtering or clearing of it, and it will make very good leather.
Heavy hides not more than half tanned may be taken out of the bark
ooze, and immersed in the pyrolignus or wood acid, taking care to handle
them well, and they will be tanned through in two or three weeks, after which
they may be taken out of the acid, and put into a pit with a layer of bark,
and remain for two or three weeks in that state until they shall be compleatly
tanned and a good colour, when they may be taken up and dried for sale.
And we do recommend the using of a little bark after the hides or skins are
taken out of the pyrolignus or wood acid, because it tends in some measure to
take away the smell of the acid, and gives the leather a better colour. The
method. we adopt for most effectually clearing the pyrolignus or wood
acid from all oily or tarry matter, and to render it fit for the use of tanning,
is the following:--We erect a copper pan or one of any other metal that
will not give the liquor a dark tinge, into which we put a quantity of pyro-
lignus or wood acid; then we put a fire under the pan, and immediately
begin to throw over the surface of the liquor in the pan a quantity of fine
ground dry spent bark, taking care, as soon as the surface of the liquor is
covered, to begin and skim all off which remains upon the surface, continuing
to throw in bark and skim off the surface till we have thrown in about half
a pound to the gallon; and we continue skimming till the liquor comes up
to a scald, or is nearly boiling; then we draw out the fire from under the pan,
and empty the liquor out of the pan into a tub or vessel or vessels to cool and

page_text: settle, and when so done it is- fit for use.
And in order that we may lose
nothing of the tanning principle we take what has been skimned from
off the heated liquor, and the residuum that is settled at the bottom of
the tub or vessel or vessels, and mix them together well with water sufficient
to extract the remaining strength from the dregs; we then let it stand
to settle, and the clear liquor is fit for the tanner's use; or if the tanner
prepares his own liquor, these skimmings and residuum may be thrown into
the leak pits or spenders, which will make a stronger liquor for tanning
than a pit of fresh ooze liquor. And for clearing the pyrolignus wood acid, as
above stated, spent fustick, or spent American bark or spent shumac, such as
the dyers have done with, or any kind of spent wood or ground wood, so that
it be free from any colouring quality which is at all likely to stain or injure
the leather, or sawdust, or ground pipe clay, or other ground dry clay or loamy
earth, so that it be free from all metallic qualities or matter, will answer
instead of bark, for throwing over the surface of the liquor in the pan for the
purpose of clearing it, as above described; but the spent bark used in the
manner mentioned above for clearing we have found most preferable. We
have used lime and whiting for the purpose of clearing the acid, and find that
with either of these it retains a tanning principle, but has not the saine effect
as when cleared in the way we have before described.
.
In witness whereof, we, the said Andrew Patten and Charles Hankinson,
have hereunto set our hands and seals, the Thirteenth day of March,
in the year of our Lord One thousand eight hundred and twelve.