A NEW MODE OR METHOD OF MORE EXPEDITIOUSLY AND EFFECTUALLY TANNING HIDES AND SKINS, AND OP Ex- TRACTING AND SEPARATING THE CATECHUIC ACID FROM THE TANNIC ACID IN THE CATECHU OR TERRA JAPONICA USED IN TANNING
Year: 1844

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
TURNBULL, of 48, Russell Square, in the County of Middlesex, Doctor of
Medicine, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Twenty-sixth day of September, in the eighth year of Her reign, did give
and grant unto me, the said Alexander Turnbull, my executors, administrators,
and assigns, Her especial licence, full power, sole privilege and authority, that
I, the said Alexander Turnbull, my executors, administrators, and assigns,
and such others as I, the said Alexander Turnbull, my executors, admini-
strators, and assigns, should at any time agree with, and no others, from time
to time, and at all times hereafter, during the term of years therein mentioned,
should and lawfully might make, use, exercise, and vend, within England
and Wales and the Town of Berwick-upon-Tweed, and in the Islands of
Guernsey, Jersey, Alderney, Sark, and Man, and also in all Her said Majesty's
Colonies and Plantations abroad, my Invention of "A NEW MODE OR METHOD
OF MORE EXPEDITIOUSLY AND EFFECTUALLY TANNING HIDES AND SKINS, AND OP Ex-
TRACTING AND SEPARATING THE CATECHUIC ACID FROM THE TANNIC ACID IN THE
CATECHU OR TERRA JAPONICA USED IN TANNING;" in which said Letters Patent
there is contained a proviso that I, the said Alexander Turnbull, shall cause
a particular description of the nature of my said Invention, and in what
manner the same is to be performed, by an instrument in writing under my

page_text: hand and seal, to be enrolled in Her Majesty's High Court of Chancery
within six calendar months next and immediately after the date of the said
in part recited Letters Patent, reference being thereunto had, will more fully
and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Alexander Turnbull, do hereby declare that the nature of my said Inventions,
and the manner in which the same are to be performed, are fully described
and ascertained in and by the following statement thereof, reference being
had to the Drawings hereunto annexed, and to the figures and letters marked
thereon (that is to say):-
The skins of animals are composed of two chief parts, the corium or cutis,
and the cuticle or epidermis. The former, which is the true skin, is a tissue
of delicate fibres crossing each other in all directions, more thickly interwoven
towards the surface than in the deeper parts of the skin; it is pervaded by
a great number of conical channels, the small extremities of which terminate
at the external surface of the skin. Those channels which are placed
The
obliquely contain nerves, secretory vessels, and cellular membrane.
cuticle or exterior coating is an insensible horny membrane, composed of
several layers of cells devoid of blood vessels.
The process of tanning consists in the combination of the gelatinous sub-
stance of which the skin is principally composed and tannic acid or tannin.
The gelatinous substance in the hides or skins is composed of carbon,
bydrogen, azote or nitrogen, and oxygen, with small portions of phosphate
of lime and of soda. This substance forms the principal part both of the
solid and fluid parts of animals; but hides and skins consist almost wholly
of gelatinous tissue. Tannin or tannic acid is a vegetable principle. procured
from nutgalls, catechu or cutch, or terra japonica, oak bark, divi divi, or the
pod of the corsalpin, coriaria, valonia, or the cup of the acorn from the prickly
oak, sumack, cork-tree bark, mimosa or wattle bark, larch bark, and many
other astringent vegetable substances. This vegetable principle is employed in
tanning leather. The gelatinous substance in skins and the tannic acid or
tannin having a strong chemical affinity for each other, the hide or skin is
converted into leather whenever tannin or tannic acid is brought into contact
with the gelatinous tissue or fibre.. The slowness of the process in tanning
leather, and the imperfect manner in which it has hitherto been accomplished,
arises from the difficulty in bringing the tannin or tannic acid into contact
with the gelatinous tissue or fibre of the skins. And although of late years
considerable modifications of the old method of tanning have been introduced,
chiefly consisting in the employment of new materials, and the application of

page_text: bydrostatic pressure, yet the result upon the whole has been merely to effect
a saving of the time consumed in tanning, and a consequent reduction of the
price, without any improvement in the quality of the leather, but rather the
reverse. This has given rise to a strong prejudice in the minds of persons
connected with the leather trade against leather tanned by any quick process.
The difficulty of bringing the tannin or tannic acid immediately and effectually
into contact with the gelatinous fibre of the skin arises from several causes,
which it may be useful to enumerate. First, in preparing the skins and
hides for the tan-pit they are steeped for a considerable time in a solution of
lime to remove the hair and epidermis. In this process the skin imbibes a
considerable quantity of lime, which has the effect of either removing from the
hide or skin a portion of the gelatinous substance in the form of soluble gelatine,
or of altering the gelatinous fibre so as to render it incapable of speedily and
effectually combining with the tannin or tannic acid, and the pores of the
skin are so impregnated with lime as to prevent the tanning principle from
operating freely or reaching the heart of the skins. Second, in tanning leather
with terra japonica or catechu, which has formed a principal ingredient in
tanning of late years, it has been found that although terra japonica contains
a much larger proportion of tannic acid than other substances, and that
considerable time has been saved in tanning with this substance, yet the
leather so tanned has been found to be very permeable to water,-light and
spongy, and of a dark reddish color; in short, leather so tanned has proved
much inferior in quality. This has been occasioned by the catechin or cate-
chuic acid or other deleterious extractives which are to be found in the terra
japonica. The catechuic acid, when exposed to the air in contact with caustic
alkalies (such as lime), becomes of a blackish color, and with carbonated
alkalies it becomes red. Hence it follows when the catechuic acid and the
other deleterious extractive matters which are found in terra japonica come in
contact with the lime with which the hide or skin is impregnated, the leather
must become brittle, porous, light in weight, of a bad color, and of a very inferior
quality. Third, when oak bark and the other materials used in tanning, and
especially oak bark, divi divi, and sumack, are mixed with water for the
purposes of tanning, they generate, by means of the action of the atmospheric
air, gallic acid; this acid is a solvent gelatine, and therefore not only not
beneficial, but injurious in the process of tanning. Besides this it causes an
expansion of the pores of the skins, and as it does not cause the tannic acid
to unite with the gelatine, the leather thus produced is light and porous, and
of an inferior quality. Gallic acid, therefore, not only cannot assist the
operation of tanning leather, but its presence must necessarily be injurious.

page_text: The gallic acid also causes the formation of a dark brown substance, which
is sufficient to color the leather throughont. The great object to be attained;
therefore, is to find out some means of removing these obstructions and
antagonist principles, and of bringing about a speedy and effectual combina-
tion of the gelatinous fibre of the hides or skins and the tanning matter, and
thus produce in a short space of time leather superior in weight, quality, and
durability to any yet produced.
The object of my improvements is to remove these difficulties and obstruc-
tions either by extracting the lime with which hides and skins are impregnated
in the process of removing the hair, or removing the hair and epidermis from
the bides or skins without the use of lime, by means not hitherto attempted.
Sugar or saccharine matter, whether obtained from the sugar cane, honey,
beetroot, turnips, potatoes, maple, or other woods or vegetable substances,
possesses the property of dissolving lime; pyroxylic or wood spirit also
possesses the same property. For the purpose therefore of extracting the
lime with which skins are impregnated in the process of removing the hair
and epidermis I prepare a solution composed of sugar and sawdust and
water in the following proportions:-Fourteen pounds of sawdust, and four
pounds of course sugar or molasses, to sixty gallons of water. The solution
may be made of sawdust alone, in which case there should be twenty-eight
pounds of sawdust to sixty gallons of water, or it may be made of any other
substance containing saccharine matter, such as beetroot, potatoes, turnips;
honey, &c.; but I prefer the solution prepared as above. These solutions may
be made with either cold or warm water, but if made with warm water they
should be allowed to cool before they are used. I then steep the hides or
skins in the solution from two to four days, according to the weight or size
of the hides or skins. The action of the sugar and pyroxylic or wood spirit
upon the lime is so rapid that in the largest skins the lime is entirely removed
and the skins are rendered fit to receive and imbibe the tannic acid, and the
operation of tanning is perfectly accomplished in a very short time. The
leather thus produced is considerably heavier and of much finer quality than
any leather produced by the present method of tanning. This method of
removing the lime is of immense importance, as it not only improves the
leather in weight and durability, but enables the tauner to produce a superior
article in a much less space of time, and at a much less expence than
heretofore. Attempts have been made to remove the lime by a preparation.
called grainer, which is mainly composed of the dung of animals. This being
of a strong alkaline nature necessarily destroys a considerable portion of the
gelatinous matter in the operation of extracting the lime; at the same time

page_text: much injury is done to the texture of the skin by its rapid action in causing
decomposition and destroying the grain side of the skin, especially in summer.
It must be obvious, however, that the moment the skin imbibes lime in any
quantity its effect and influence on the hide or skin is to a considerable extent
permanent and destructive, I therefore have directed my attention to the
best method of removing the hair and epidermis without the aid of lime.
There can be no doubt that lime has in general been used in removing the
hair from skins because it has been found the most effectual in preventing
putridity. It is well known that putrefaction does not take place without
the presence of azote or nitrogen. This is contained in the gelatinous fibres
of hides and skins in a considerable quantity. There have been various
attempts made to soften the epidermis or roots of the hair so as to remove
the hair without the use of lime, by producing an incipient putrefaction.
These have been generally abandoned, not only on account of the risk to
human life attending the process, but because great loss was sustained in the
hide by reason of putrifaction and consequent partial destruction of the
gelatinous tissue. Sulphuric acid, sour milk, fermented barley, rye, or flour
water, and other acidulous matters have also been applied for the same
purpose; but these methods have been found to occupy too long a time, and
the hides or skins have been thereby much injured. Removing the hair by
means of acids is effected by the acids causing a solution of much of the gela-
tine, and the hair is in consequence loosened, but the gelatineous matter in the
skin is thereby injured and deteriorated, and a considerable portion of the skin
destroyed. When fermented barley, rye, or flour water is used, the operation
upon the hide is comparatively slow, because the fermentation is going on.
principally between the ferment introduced and the vegetable preparation, and
the skin being imperfectly acted upon, the process is rendered long and tedious.
The methods by which I remove the hair from hides and skines are, first,
by steeping them in a solution of sugar or other saccharine matter, whether
obtained from honey, potatoes, beetroot, wood, or any other substances;
secondly, by steeping the hides and skins in a solution of muriate of soda. By
the first method the sugar or saccharine matter which contains no nitrogen is
brought into contact side by side with the hides or skins, and an instan-
taneous, rapid, and regular action is thereby created and continued between the
sugar and the hides or skins, which causes the gelatine or true skin to
swell or expand, and, without acting upon or causing any injury to the
gelatinous fibre of the hides or skins, loosens the epidermis and renders the
removal of the hair a matter easily effected. By the second method the

page_text: mixture of muriate of soda and water contracts the epidermis without acting
upon the gelatine, and thus loosens and separates it from the true skin, by
which means the hair is easily removed without injuring the gelatinous matter
which forms the basis of the leather. The effect in both operations is the
same, for as the saccharine matter by force of its operation upon the nitro-
genous substance in the skin causes the gelatine or true skin to expand, and
thus loosens the epidermis, while at the same time the fibre is preserved from
putrefaction, so the solution of muriate of soda, whilst it contracts or destroys
the epidermis and renders the removal of the hair easy, also tends greatly to
preserve the fibre of the hide or skin from putrifaction. The object to be
attained is to prevent putrifaction in the skins, which not only destroys the
gelatinous fibre, but is in its operation and effect injurious and dangerous to
human life. This great object is effected by the means I have mentioned,
and speedily removes the bair from the hides and skins at an expence much
less than the old process of removing it by means of lime. The solution of
sugar by which I effect the operation of removing the hair from hides is
prepared in the following proportions:-Fourteen pounds of coarse sugar or
molasses to one hundred gallons of water. This solution works most advan-
tageously when kept at a temperature between 50° and 80° Fabrenheit, and
although its action may be increased by a little additional heat, yet it would
be unsafe to raise the temperature much beyond the point I have mentioned,
and it would be decidedly injurious to lower it below 50°. The skin should
remain immersed in this solution from five to ten days, according to its size,
when the hair may be easily removed. The solution of muriate of soda is
prepared in the following proportions,-fourteen pounds of common salt to one
hundred gallons of water. This solution I have found to work most advan-
tageously when kept at a temperature between 70° and 100° Fahrenheit, and
although its action may be increased by a little additional heat, yet it would
be unsafe to raise the temperature much beyond 100°, and I have found it
decidedly injurious to lower it much below 70° Fahrenheit. The skin should
remain immersed in this solution from three to six days, according to its size.
When the hair is removed by either of the means above mentioned, or when
the lime has been extracted by the process I have before described, the skins
and hides will be found to be in a state to receive and imbibe the tannic acid
much more rapidly and effectually than by any other means.
Having thus removed one of the obstructions to tanning, I propose to get
rid of the other difficulties I have pointed out by separating the japonic or
catechuic acid and other deleterious matter to be found in terra japonica from

page_text: the tannic acid, and also to prevent the formation or generation of gallic and
ellagic acids when oak bark, divi divi, valonia, and other tanning materials
are used. The first I accomplish by grinding catechues into fine powder and
then mixing the powder with either warm or cold water until it is thoroughly
dissolved, and when cold, pouring the liquid into a large cylinder or tank made
of any material not injuriously acted upon by acids, with a bottom made of
fine wire gauze, calico, linen, or other porous material. By this means the
catechuic acid, extractive, and other deleterious matter to be found in the
catechues are retained by reason of their being insoluble in cold water, and
a pure tannin liquid, freed from these injurious ingredients, is obtained. The
cylinders or tanks may be formed of any shape or size, according to the extent
or magnitude of the business to be carried on. The purified liquid thus
obtained from terra japonica will be found much more effectual in preserving
sails of vessels and linen cloth exposed to the weather than the terra japonica
as now used. To prevent the formation of gallic and ellagic acids, which are
generated in the tannin liquid when it is composed of oak bark, divi divi,
valonia, and other tanning materials by the operation of the atmospheric air,
I propose to grind the materials into fine powder, and to exclude the atmo-
spheric air from operating upon it during the time the process of tanning is
going on, in the manner herein-after described by me in my mode of tanning
hides or skins. The hides or skins being prepared in the manner before
described, and being well washed and cleansed, I proceed to tan them by
two different modes,-first, by the application of a new physical force, different
from ordinary capillary attractive or hydrostatic pressure; and secondly, in
pits or tanks so constructed by communicating with each other as, by the
means after described, to keep up a general and constant agitation and circula-
tion of the tanning liquid until the hides or skins are tanned. It may be
necessary here to observe, that when two liquids of different densities are
separated by a membrane or septum, two opposite currents are established in
contrary directions, the one outwards and the other inwards; the greater
current passes through the membrane and accumulates on the side where the
liquid is of the greatest specific gravity, on whichever side of the membrane it
may be placed, and the lesser current flows through the membrane to the
opposite liquid, and these interchanges continue acting until such time as the
specific gravity of the fluids on each side of the membrane becomes alike,
unless a chemical change or obstruction takes place to prevent it. The current
in one direction is called endosmosis, that in the opposite direction exosmosis.
This law has been known and recognized for some time, but it has never been
applied for the purposes of tanning by bringing liquids containing tannic acid

page_text: into contact with the gelatinous matter in the hides and skins so as to cause a
thorough chemical union between them.
My discovery or Invention consists in the application of this physical force
in the tanning of hides or skins. To secure the advantages of endosmosis and
exosmosis in the tanning of hides and skins, I grind oak bark into powder; I
then form the hide or skin to be tanned into a bag by sewing it together,
leaving only sufficient room to introduce the oak bark. The ground oak bark
is then to be introduced into the bag in the proportion of two pounds to every
pound weight of the wet hide when prepared as above. The hide should
then be sewed up, leaving only a small neck or aperture by which to introduce
the water; I then fill the bags so formed with either cold or warm water, and
when full I fasten the neck or aperture by a flange and screw so as to exclude
the atmospheric air. This done I introduce the bag or skin into a box filled
with tannin liquor formed of terra japonica when freed by the process before
described from catechuic acid and extractives. The boxes should be of the
dimensions stated below, and may be formed one above another, as described
in the Drawing hereunto annexed, marked No. 1. For bullocks' hides the
boxes should be ten feet long, three feet broad, and one and a half deep.
For calve's and other skins the boxes should be five feet long, two feet broad,
and one deep, and one foot and a half space between each box, A being the
tanks or boxes; B, the waste pipes to conduct the liquor as it exudes, leading
to C, the main pipe which is to carry off the surplus liquor into D, the main
tank or reservoir. The waste pipes have two objects, first, to carry off the
superfluous liquor as it exudes from the hides, and also as safety valves in case
any of the bags formed of the hides or skins should burst, or the sewing give
way. The terra japonica when purified as above is not injuriously acted upon
by the atmosphere, and the tannic liquor composed of oak bark being mixed
inside the hide or skin, and being thus excluded from the operation of the
atmospheric air, does not generate gallic acid, and the combination of the
tannic acid and the gelatins in the skin is speedily effected. In order to
increase the specific gravity of the liquor in the boxes or tanks, and thus
accelerate the action, I add sugar in the proportion of fourteen pounds to
one hundred gallons of the mixture of terra japonica. The two liquids
being thus separated, the process of endosmosis and exosmosis is secured, and
the tannic acid passes rapidly through the skin or hide until it is perfectly
tanned. The bags or hides when they become partially empty by exudation
should be filled again with water until the hide or skin is completely tanned.
During the operation of tanning it will be necessary to add to the weight of
the liquid in the boxes in order to keep up the action. This is accomplished

page_text: by adding a small quantity of sugar to the mixture of terra japonica. Valonia
will rank next to purified tannic acid from terra japonica, and may be used
similarly to terra japonica. Ground valonia may be introduced into the bag
in the proportion of about one half less than the oak bark; mimosa, divi divi,
sumack, and other substances containing tannic acid may be used in the same
proportions as valonia. Terra japonica ought to be introduced into the bag
after the impurities are removed in the form of tan liquor in the proportion of
fifty pounds to the hide. The average weight of each article to be used ought
to be two pounds of oak bark to each pound of wet hide. Two pounds of
valonia, mimosa, sumack, or divi divi, are equal to four pounds of oak bark,
and one pound of terra japonica is equal to four pounds of oak bark, and to
two pounds of valonia, sumack, &c. These proportions are calculated for either
hides or skins. The bags ought to be turned occasionally, and when. almost
empty ought to be filled again with water, or a mixture of terra japonica, when
the impurities are to be removed, and the tanks or boxes ought also to be
kept replenished with the mixture of terra japonica until such time as the
hides or skins are thoroughly tanned. Tanning by means of pits or tanks, so
constructed as to create and keep up a general and constant agitation and
circulation of the tanning liquor, is accomplished by the construction of pits or
tanks sufficiently large to contain hides and skins placed horizontally one upon
another in connection with a forcing pump, pipes, &c., as described in the
Drawing hereunto annexed, marked No. 2. These pits or tanks are to be
filled up with a sufficient quantity of tanning liquor or ooze composed either
of terra japonica, or oak bark, divi divi, valonia, sumack, &c., in the propor-
tions before mentioned, so as to leave room only for the hides and skins. The
hides or skins are to be placed in the pits or tanks one upon another, as in the
ordinary mode of tanning. These pits when filled with the skins and tannin
liquor or ooze are to be closed at top so as to exclude as much as possible
the injurious operation of the atmospheric air. The tanning matter or liquor
must then be put into and kept in a state of constant agitation or circulation.
This is effected by means of a suction pump connected with the pits or tanks
at the bottom and top, as described in the Drawing hereunto annexed, marked
No. 2. A is the suction pump; B are the pits or tanks; C, the suction pipe;
D are the tubes or pipes from the bottom of the pits or tanks in connection
with the suction pipe; E is the main forcing pipe round and in connection
with the top of the pits or tanks; F are the tubes or pipes from the main
forcing pipe into the top of the pits or tanks; and G represents the connecting
pipes at top to prevent the tanks or pits from overflowing. By the action of
the suction or forcing pump the tanning liquor or ooze is speedily extracted

page_text: by means of the tubes at the bottom of the pits or tanks through the suction
pipe from all the pits or tanks, and at the same time it is forced again
through the main pipe E into the different pits by the tubes or pipes F', thereby
keeping up a general agitation and circulation of the liquid through the whole
series of pits at the same time.. These pits or tanks may be constructed in
sheds or rooms, and may consist of any number one above another and side
by side. The Drawing hereunto annexed before referred to, marked No. 2,
represents six pits side by side. If it is desired to sink the pits or tanks in the
earth, they should be constructed according to the Drawing hereunto annexed,
marked No. 3. No. 1 is the suction or forcing pump; No. 2, the tanks or
pits; No. 3, the suction pipe; No. 4, tubes or pipes in connection with the
suction pipe entering at the top and extending nearly to the bottom of the pits;
No. 5, stopcocks to ditto; No. 6, the main forcing pipe; No. 7, the tubes or
pipes in connection with the pits or tanks entering at top from the main or
forcing pipe; No. 8, stopcocks to ditto; and No. 9, waste pipes to prevent
the tanks overflowing. The operation of both is the same, with this exception,
that as in the latter the pits are sunk in the ground, the tubes by which the
liquor is withdrawn are obliged to enter at the top and be continued down the
tanks nearly to the bottom. By these means, although the injurious action of
the atmosphere upon the tannin liquor is not so completely prevented as by
tanning the hides by sewing them into bags, as before described, yet the
formation of gallic acid is in a great measure prevented, and the gelatinous
body in the hides or skins is brought almost as speedily and effectually into
contact with the tannic acid as by the principle of endosmosis and exosmosis
when produced by the hides being formed into bags and placed in boxes, as
before described. Another and not an unimportant advantage is gained by
separating the catechuic acid and other extractive and deleterious matter
from the terra japonica. The deleterious matter retained or deposited in the
cylinders or tanks is at least fifty per cent. of the quantity of terra japonica
dissolved. This refuse or deposit is capable of being again purified and
rendered applicable to tanning. For this purpose I collect the deleterious
extractive or deposit from the cylinders and place it in stoves or drying pans
and apply to it a heat equal to 160° Fahrenbeit, leaving it at the same time
exposed to the atmospheric air, and keeping it continually stirred until it
assumes the color and appearance of the original pulverized terra japonica:
The material thus obtained, upon being again subjected. to filtration in the
same manner as the original terra japonica, will be found to yield nearly as
much tannic acid as in the first instance. This will be found to be an
immense saving. I may here observe, that my method of extracting the

page_text: lime from hides or skins when the hair has been removed by lime, and my
method of removing the hair without the use of lime by the means before
described, are such decided improvements, that hides and skins when so
prepared may be tanned in the common or ordinary manner by terra japonica,
purified as above, and by other ordinary tanning matter, with much greater
facility than heretofore, and the leather thus produced is of far greater weight
and much better quality than any heretofore produced. The advantages to be
derived by my improvements in tanning leather are, first, a great additional
weight of leather, especially in calf skins; second, leather of a much better
quality, soft, and not liable to crack or stain; third, a considerable diminution
in the expence; and, fourth, the tanning is effected in one quarter of the time
consumed in the present mode of tanning.
Having thus stated the nature of my improved methods of tanning hides
and skins, and of separating or extracting the japonic or catechuic acid or
catechin or other extractive and deleterious matter from the tannic acid, and
preventing the formation of gallic and ellagic acid in other tanning liquor,
and the manuer of carrying them into effect, I think it essential to state
that I do not claim the principle of tanning hides or skins by sewing them
into bags, nor by simply filling them with liquor, but I do claim, and my
Invention consists, in the following improvements in the tanning of hides
and skins.
First, I claim the discovery of the means of extracting the lime with which
bides and skins are impregnated, in removing the hair by the application of
sugar or other saccharine matter, whether obtained from honey, sawdust,
turnips, potatoes, or other substances.
Second, I claim the discovery of the means of removing the hair or
epidermis from hides and skins without the use of lime by the application of
sugar or other saccharine matter, whether obtained from potatoes, sawdust,
beet root, turnips, or other substances.
Third, I claim the discovery of the means of removing the hair or epidermis
from hides and skins without the use of lime by the application of muriate of
soda or common salt.
Fourth, I claim the discovery of the means of separating the japonic or
catechuic acid, or other extractive or deleterious matter, from the tannic acid in
terra japonica.
Fifth, I claim the discovery of the means of obtaining tannic acid from the
refuse or deposit of the terra japonica in purifying terra japonica.
Sixth, I claim the discovery of the means of preventing the formation
or generation of gallic and ellagic acid when oak bark, sumack, divi divi,
valonia, and other materials are used.

page_text: Seventh, I claim the discovery of an improved mode of tanning leather by
means of endosinosis and exosmosis with the materials and in manner before
described, without the aid of hydrostatic pressure.
Eighth, I claim the discovery of an improved mode of tanning by means
of a general and constant agitation and circulation of the tanning liquor, com-
posed of the materials before mentioned, from top to bottom and from bottom
to top of the pits.
Ninth, I claim the improved method of tanning hides or skins in pits in
the common and ordinary manner by first extracting the lime from the
hide or removing the hair without the use of lime, and using terra japonica
when purified, or other tanning liquor, prepared in the manner before
described.
In witness whereof, I, the said Alexander Turnbull, have hereunto
set my hand and seal, this Twenty-fifth day of March, One thousand
-eight hundred and forty-five.
A. TURNBULL (L.S.)
AND BE IT REMEMBERED, that on the Twenty-fifth day of March,
in the eighth year of the reign of Her Majesty Queen Victoria, the said
Alexander Turnbull came before our said Lady the Queen in Her Chancery,
and acknowledged the Instrument aforesaid, and all and every thing therein
contained and specified, in form above written. And also the Instrument
aforesaid was stamped according to the tenor of the Statute made in the fifty-
TL