IMPROVEMENTS IN THE MANUFACTURE OF CHARCOAL
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Sir FRANCIS
CHARLES KNOWLES; of Lovell, in the County of Bucks, Baronet, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Ninth day of
November (One thousand eight hundred and fifty), in the fourteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Sir Francis Charles Knowles, my exors, admors, and assigns, Her
especial licence, full power, sole privilege and authority, that I, the said Sir
Francis Charles Knowles, my exors, adññiors, and assigns, or such others as
I, the said Sir Francis Charles Knowles, my exors, adiñors, or assigns, should
at any time agree with; and no others; from time to time and at all times
during the term of years therein expressed, should and lawfully might make,
use, exercise, and vend, within England, Wales, and the Town of Berwick-
upon-Tweed, in the Islands of Guernsey, Jersey, Alderney, Sȧrk, and Man,
and in all Her Majesty's Colonies and Plantations abroad, my Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF CHARCOAL ;" in which said .Letter's
Patent is contained a proviso that I, the said Sir Francis Charles Knowles,
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 hand and seal, to be inrolled 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, as in and by the same,
reference being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance. with the said proviso, I, the said Sir
Francis Charles Knowles, do hereby declare that the nature of my said Inven-
tion, and the manner in which the same is to be performed, are fully described
and ascertained in and by the following statement thereof, reference being had
to the Drawing hereunto annexed, and to the figures and letters marked
thereon, that is to say :-
My Invention or process consists in the carbonization of spent tanners' bark,
bog peat, and other ligneous matter, without the necessity of employing
external fireing; and I also obtain the faculty of collecting all gaseous or other
volatile products that are attainable by the process of dry distillation.
DESCRIPTION OF THE DRAWING.
Figure 1, a circular furnace or cupola, built of brickwork, made parallel at
the upper part, as at A, A, the lower part B, B, being made conical, and
resting or terminating on an oblong cast-iron box C, C, open at the top. D, a
spindle fitted and passing through the box, on to which are fitted a circular
plate E at each end of the inside of the box, see Figure 2. F, F, F, wrought
iron bars fitted into the end, placed round about two thirds of the circum-
ference, and extending the length of the box, forming a set of fire bars when
the bars are upwards, as seen in Figure 2. When the charge is required to
be drawn the bars are turned downwards, when the space inside the bars
will be filled through the opening between the bars from the cupola above.
The bars are then brought back into their former position, and the contents
of the drum of bars falls into the coned part of the iron box H, from
which it is discharged through the flap I. J, a hand wheel fixed on the
spindle K for giving motion to the drum of fire bars. L, a worm working
into the wheel M fixed on the spindle D. N, N, N, carriage for carrying
the spindle. I, an iron flap, air-tight when closed, fitted with spindle, lever,
and counterbalance weight O. P, a cover with projecting ring to drop into
a circular ring Q, to form a water joint for closing the top of the cupola. R, a
pipe through which the vapour, gas and air are exhausted from the cupola
by any well-known means, such as pumps or fan, &c. &c. S, counterbalance
with rope T and pulleys U, U. Into the furnace already described and exhi-
bited in the annexed Drawing put a quantity of dry shavings, so as to cover
the semicircular revolving grate or box, Figure 2, and when lighted add dry
spent tanners' bark, dry or compressed bog peat, or any of the particular
substance to be operated upon. At the time when the strata of ignited matter
is about two or three feet thick or deep, add, in small quantity, from time to
time, fresh spent bark or other substance intended to be converted into char-
ccal, say from one to two bushels at each time. The pumps are now set to

page_text: work, or the fan is put into revolution, by which the atmospheric air is drawn
downwards and through the mass, and by so pumping or turning the fan we
feed or supply the furnace with the dose or quantity of atmospheric air required.
to carbonize but not sufficient to burn or decompose the substance operated
upon. Now adjust the extremity of the tube or outward delivery of the fan
into the tube, pipe, or connection of a purifier of gas, and thence by pressure
drive the gas, or any other volatile product that may be formed, into a fixed or
portable gasometer, as circumstances shall require or determine, whereby to
retain, collect, and purify any gases or other volatile product that may come
over during the process of carbonizing already described. When the furnace
is completely full of charred or ignited matter, draw out about one fifth
part or twenty per centum of the contents by turning the circular hand wheel
or lever J, and then by descenting the valve I the charcoal will fall into the
cooling boxes or cases which are provided with covers that seal nearly herme-
tically close; from these, when cool enough, the charcoal is transferred to
bags, &c.
After drawing any quantity of charcoal, it is best and advisable to
supply the furnace at the top with an equal quantity of raw material; by this
means, and pumping, we keep a regular circulation of caloric and matter,
whereby I maintain an uniform intensity and obtain an uniform product.
When the work of the day is terminated, I close the upper damper P, leaving
only a small space, say one quarter of an inch, all round to permit the escape
of vapour or gas during the night. The greatest care is required to be taken
when at work to lute up the external joints, and also the lower valve or
discharging point of the furnace. The best lute for this purpose is a mixture
of linseed meal, pipe clay, and linseed oil, mixed up thick as mortar. The
luting is most important, as every small hole, crack, or opening will let
in oxygen enough to decompose a great quantity of charcoal, and to pro-
duce considerable loss to the manufacturer. When the contents of the
furnace are very compact or dense, either from the nature of the raw material
or the length of time the operation may have previously required, or from the
quantity of aqueous matter that is yet remaining in the mass generally, or
from any other cause, unlute the lower valve and open it fully, and, if the.
draught of air is not visibly improved thereby, I turn the circular grate and
discharge a few bushels of charcoal; in a few minutes a sharp upward current
will be established, passing upward through the circular grate and escaping at.
the top of the furnace. When the air has pervaded and penetrated the whole
mass, which is ascertained by the rapidity of the ascending current and the
heat it communicates, I am certain that the whole mass is ignited and
undergoing perfect combustion; if at this time a too great degree of heat
is experienced, and white ashes form with rapidity at the surface of the

page_text: furnace, the lower valve must be closed and luted, and the upper damper must
be closed entirely, and fresh-bark added. When it is necessary to collect the.
gaseous or other volatile products, the damper on the top must be closed to
such a degree as to permit air to enter, but nothing to escape outwards, and
the fan or pistons must be worked constantly and with its greatest speed; by
this means the whole of the gas, volatile vapours, &c. are drawn downwards
through the ignited mass of charcoal, and then into the well of the fan or
pumps, after which it may undergo the ordinary purification common to
gas, &c., and thence pass into a fixed or portable gasometer for consumption
and use.
Another part of my Invention consists of compressing spent tanners' bark in
moulds, and then saturating the same with tar in a boiling or highly heated
state, by immersing the blocks so moulded or compressed in the heated tar till
they are saturated. The blocks are then allowed to drain, and charcoal is
made therefrom by the means above described, or by placing the blocks in
ordinary retorts heated externally.
I claim, first, the means herein described of providing charcoal from light
porous vegetable substances, such as spent tanners' bark, compressed or air-
dried bog peat; or other ligneous substance of small specific gravity.
Second, the means and power of collecting the gaseous and volatile products
that are formed during the dry distillation or decomposition of the raw material
without employing external fireing or heating.
In witness whereof, I, the said Sir Francis Charles Knowles, have
hereunto set my hand and seal, this Eighth day of May, in the year
of our Lord One thousand eight hundred and fifty-one.