IMPROVEMENTS IN THE MANUFACTURE OF TANNIC BLACK AND ITS APPLICATION FOR PAINTS AND OTHER USEFUL PURPOSES 33
Year: 1883

page_text: LETTERS PATENT to William Gostwyck Gard and Thomas Henry Cobley, both
of Dunstable, County of Bedford for an Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF TANNIC BLACK AND ITS APPLICATION FOR PAINTS AND
OTHER USEFUL PURPOSES
33
PROVISIONAL SPECIFICATION left by the said William Gostwyck Gard
and Thomas Henry Cobley at the Office of the Commissioners of Patents on
the 22nd May 1883.
WILLIAM GOSTWYCK GARD and THOMAS HENRY COBLEY, both of Dunstable,
County of Bedford. "IMPROVEMENTS IN THE MANUFACTURE OF TANNIC BLACK,
AND ITS APPLICATION FOR PAINTS AND OTHER USEFUL PURPOSES "
Our Invention consists in an improved process for manufacturing tannic black
from substances containing tannin, either free or in combination with other substances
or inatter. Where the tannin is combined, such as in leather waste, we add to
this soda in the form of caustic or carbonate of soda, or a mixture of the two, in
proportion of from 1 cwt. to 1 cwt. and a half to every ton of leather waste,
according to the amount of tannin in the waste.
This mixture is brought into a suitable vessel, preferably steam jacketted, and
sufficient water run in to cover the mass, this is kept at a temperature not exceeding
180 to 200° Fahrenheit for several hours, until the tannin and a large portion of
the gelatine is dissolved.-This solution then removed, and run into, a precipi-
tating tank, where it is precipitated by means of a combination of iron pyrolignate
or acetate of iron, or chloride of iron, or a mixture of these or other compounds or
salts of iron.-The quantity employed should be sufficient to deposit the whole of
the tannin present, together with the gelatinous matter present, which precipitation
may be completed by the addition of alum or a salt of alumina.-This precipitate
is got into a solid state by any convenient means, as for instance a filter press, and
after washing is dried by any known method or suitable means. For many

page_text: -
applications, particularly for paint, the drying must be carefully done, and should
only be carried to within about 10% of absolute dryness, when it may be ground
with a dryer, such as powdered tannic black made by the direct process of decom-
position of leather waste &c, by chloride of iron, powdered leather, charcoal, or any
other suitable black substance, readily combining with or absorbing gelatinous
matter.
The liquor from the pressing or dehydrating of the precipitate is used over again
with a fresh portion of soda, for dissolving a fresh quantity of leather waste, until
the liquor becomes so saturated with soda salt that it is of sufficient value to boil
down. This is particularly valuable in the case of acetate of soda, as this will form
a source of profit, and cheapen the production. In the case of leather waste being
used, the sole leather should preferably be treated alone, and the grease removed
from the upper leather before it is treated, more especially when caustic soda is
used.
Other waste substances may be employed containing tannic acid and gelatinous
matter, the separate solutions being mixed together, and in such state treated with
the iron salts herein described, the amount of iron required being in excess of the
tannin present, alumina being added to fix the same

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Gostwyck Gard and Thomas Henry Cobley in the Great Seal
Patent Office on the 22nd November 1883.
WILLIAM GOSTWYCK GARD and THOMAS HENRY COBLEY both of Dunstable in
the County of Bedford IMPROVEMENTS IN THE MANUFACTURE OF TANNIC BLACK
AND ITS APPLICATION FOR PAINTS AND OTHER USEFUL PURPOSES
Our Invention consits in an improved process of manufacturing Tannic Black
from substances containing Tannin either free or in combination with other
substances or matter.
In carrying out our Invention we proceed as follows.-The material containing
Tannin such as Leather waste or any other material containing Tannic Acid is
brought into a suitable vessel capable of being heated with Steam then preferably
steam-jacketted or if with direct steam then under pressure.
A solution of Soda is added either Carbonate or Caustic Soda or a mixture of
the two, or Pyrolignate or Acetate of soda (recovered liquor from precipitation with
Pyrolignate or Acetate of Iron) equivalent to one Cwt to 11 Cwt dry weight of
Soda per ton of material such as Leather waste, varying in proportion to amount
of Tannin and Gelatine or Extractive matter contained in the material.-This is
kept at from 180° to 200° Fahrenheit until the whole of the extractable amount of
Tannin is rendered soluble.
Where time is not an object the solution may be prepared by a cold digestion
particularly if the material is in a finely divided state.
Where Acetate of Soda is used for making the solution particularly where the
Tannic Black is to be used for facing or coating or admixing with other black
materials, so as to produce a bright Black, the continuous solution of Acetate of
Soda used when it becomes Acid, may be neutralised with ordinary soda, as
required.
The solution obtained by the methods and means herein before mentioned is then
removed or run into a Precipitating Tank, and precipitated by means of Pyrolginate
or Acetate of Iron where a continuous process, or the recovery of the Soda as
Acetate of Soda is desirable, or with any other Salt of Iron, for instance the
Chloride. To break up the Gelatine, so as to render the Black available for Oil
paint and Printing Ink, it is preferable, instead of a mechanical admixture of the
Precipitate and the substances referred to, to introduce such substances or materials
into the Solution and keep the mass well stirred while Precipitation is going on, so
that the particles in a finely divided state get coated or faced with Tannic Black.-
The substances we prefer to use, are powdered or ground Tannic Black obtained by
the direct process, common Lamp Black ground leather Coal and Shale Carbon.
In mixing or coating Powdered Tannic Black, a Tannic Solution as free as
possible from Gelatine should be employed.
The quantity of Iron employed should be sufficient to deposit the whole of the
Tannin or Tannic Acid present, which will vary from time to time, but which may
be easily tested in the ordinary way. To facilitate the deposition, Alum, Sulphate
of Alumina, Pyrolgnate or Acetate of Alumina is added, until the liquor is sufficiently
clear.
The precipitate, either pure or admixed is passed through a Filter or Filter press,
washed and dried by any known or convenient means. The Liquor from the
pressing or dehydrating of the Precipitate is used over again to dissolve fresh
quantities of material with the addition of fresh quantity of Soda until it becomes
so saturated with Acetate of Soda, as to be worth boiling down and chrystallising
when it may be sold for covering part of the cost of manufacture. The improved

page_text: Tannic Black may be ground into paint in the ordinary way or mixed with various
ingredients for varying the shades known to every color maker.
The ordinary precipitated Black may be employed mixed with Albumen or
Casein for printing paste, in Calico Printing, commonly known as Steam printing.
A cheap method of preparing the Printing Paste is grinding up the Precipitate
in the Serum of Blood to the proper consistency when it is fit for use.-Other waste
substances may be employed containing Tannic Acid and. such solutions separately
obtained, mixed together, and in such a state treated with the Iron Salts and in the
manner herein before described.
Having thus described the nature and object of our Invention and in what
manner the same is to be performed or put in practice We hereby declare that We
claim the said Invention of Improvements in the manufacture of Tannic Black and
its application for paints and other useful purposes substantially as hereinbefore
set forth and described.
In Witness whereof we the said William Gostwyck Gard and Thomas Henry
Cobley have hereunto set our hands and seals this twenty-first day of
November in the year of our Lord one thousand eight hundred and eighty
three
Witness to the signatures of
Wm G. Gard & Thos H
Cobley
GEORGE SMITH
(L.S.)
WM GOSTWYCK GARD
THOMAS. HENRY: COBLEY (L.S.)
Accountant.
Dunstable.