IMPROVEMENTS IN APPARATUS FOR ROASTING OR DRYING COFFEE, CHICORY, AND OTHER GRAINS, SEEDS, OR VEGETABLE PRODUCTS."
Year: 1879

page_text: LETTERS PATENT to Edward Bonser and Alfred Edward Bonser, both of
No. 87, Tower Hill, in the City of London, Tea and Coffee Merchants, for the
Invention of "IMPROVEMENTS IN APPARATUS FOR ROASTING OR DRYING
COFFEE, CHICORY, AND OTHER GRAINS, SEEDS, OR VEGETABLE PRODUCTS."
PROVISIONAL SPECIFICATION left by the said Edward Bonser and Alfred
Edward Bonser at the Office of the Commissioners of Patents on the 20th
September 1879.
EDWARD BONSER and ALFRED EDWARD BONSER, both of No. 87, Tower Hill, in
the City of London, Tea and Coffee Merchants. "IMPROVEMENTS IN APPARATUS
FOR ROASTING OR DRYING COFFEE, CHICORY, AND OTHER GRAINS, SEEDS, OR
VEGETABLE PRODUCTS."
This Invention consists in improved apparatus, by means of which the flame
produced by burning gas is applied directly to the coffee, chicory, or other substance
to be roasted or dried, instead of heating the metal or other vessel in which the
substance to be roasted or dried is contained.
The mode in which the Invention is carried into effect is as follows:-
The substance to be roasted or dried is enclosed in a suitable perforated cylinder,
which is by preference furnished with internal ledges arranged so that when the
said cylinder is caused to rotate each particle of the substance to be roasted or dried
contained in the said cylinder shall be successively brought into contact with a
flame which is produced by gas burning from a burner within the said cylinder.
Other mechanical arrangements, such for instance as inclined planes, may be used,
so as to cause the coffee or other substance to pass, repeatedly through or in contact
with the naked flame; or the burner itself may be caused to rotate so as to expose
successive portions of the substance to the direct action of the flame, or an octagonal
or hexagonal or other suitable vessel may be used instead of a cylinder.
It is necessary that the flame should be produced by a suitable burner having a
sufficient supply of atmospheric air, so as to give a smokeless or blue flame. A blast
of air may be used with the gas if desired.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Bonser and Alfred Edward Bonser in the Great Seal Patent
Office on the 19th March 1880.
EDWARD BONSER and ALFRED EDWARD BONSER, both of No. 87, Tower Hill, in
the City of London, Tea and Coffee Merchants. "IMPROVEMENTS IN APPARATUS
FOR ROASTING OR DRYING COffee, CHICORY, AND OTHER GRAINS, SEEDS, OR
VEGETABLE PRODUCTS."
This Invention consists in improved apparatus, by means of which the flame
produced by burning gas is applied directly to the coffee, chicory, or other substance
to be roasted or dried, instead of heating the metal or other vessel in which the
substance to be roasted or dried is contained.
The mode in which the Invention is carried into effect is as follows:-
The substance to be roasted or dried is enclosed in a suitable perforated cylinder,
which is by preference furnished with internal ledges arranged so that when the
said cylinder is caused to rotate each particle of the substance to be roasted or
dried contained in the said cylinder shall be successively brought into contact with
a flame which is produced by gas burning from a burner within the said cylinder.
Other mechanical arrangements, such for instance as inclined planes, may be used,
so as to cause the coffee or other substance to pass repeatedly through or in contact
with the naked flame; or the burner itself may be caused to rotate so as to expose
successive portions of the substance to the direct action of the flame, or an
octagonal or hexagonal or other suitable vessel may be used instead of a
cylinder.
It is necessary that the flame should be produced by a suitable burner having a
sufficient supply of atmospheric air so as to give a smokeless or blue flame. A blast
of air may be used with the gas if desired.
Having described the nature of the said Invention we will now proceed to describe
more pasticularly the manner of carrying the same into effect, reference being had
to the accompanying Drawings.
Fig. 1 represents partly in side elevation and partly in section a roasting apparatus
constructed according to our Invention.
Fig. 2 represents the same roasting apparatus partly in transverse elevation and
partly in transverse section.
The same letters and figures of reference indicate the same parts in each
Drawing.
A, A, is a perforated cylinder of sheet iron or other suitable material closed at
the ends. The perforations, which are shewn on a portion only of the cylinder
marked A¹, must be too small for the coffee berries or other substance to be roasted
or dried to pass through, and should not be so numerous as to allow the heat from
the gas to escape too rapidly. We prefer to make them about one eighth of an
inch in diameter, and about one inch apart. This cylinder is furnished with and
affixed to a hollow axle B, B, which axle is provided at one end with a crank B¹, B¹,
or with some other suitable means of communicating rotation to the said axle,
which being firmly secured to the ends of the cylinder causes the cylinder itself to
The cylinder is also provided with a door or flap C, which is hinged to the
cylinder and fastened by a hasp or other suitable fastening C', through which the
coffee or other substance to be roasted or dried is introduced into and withdrawn
from the cylinder. D, D, D, D, are ledges or shelves of iron or other suitable
material, which as the cylinder is rotated lift the coffee through part of a revolution,
and then allow it to fall through or near to the flame of the gas, as hereinafter
rotate.
described.
E is a gas pipe which conveys a supply of gas to F, the air mixer or chamber in
which the gas becomes admixed with atmospheric air, and the mixed gas and air
passes through the opening F¹ into the hollow axle B, B, of the cylinder, which

page_text: axle is perforated with holes B2, B2, and preferably covered with wire gauze B³, B³,
and so forms an atmospheric gas-burner giving a blue or smokeless flame. F2 is a
collar which is turned out to receive the end of the hollow axle B, B, without
allowing gas to escape. In some cases we prefer to make the hollow axle B, B, a
fixture, and let the cylinder rotate on it instead of both rotating together.
G, G, are the standards or supports for carrying the cylinder.
The apparatus is used in the following manner, which we describe as applied
specially to the roasting of coffee :-The modifications which are necessary when
the apparatus is applied to the roasting or drying of other substances are very
slight, and depend simply on the degree of roasting or drying required.
The gas having been turned on at the tap E', and lighted by applying a light to
the hollow axle in the vicinity of the holes B2, B², a charge consisting of a suitable
quantity of the coffee to be roasted is introduced through the door C, which is then
fastened and the cylinder is caused to rotate. By this rotation the coffee is lifted by
the ledges or shelves D, D, D, D, and caused to fall either on to the hollow axle
forming the burner B, B, or through or near to the flame of the gas issuing from
the holes B2, B2. The cylinder must be kept in rotation at a moderate speed until
the roasting is nearly completed, when we prefer that the gas should be turned out
and the rotation continued for a short time longer until the roasting is quite
completed, the final stage of roasting being effected by the heat remaining in the
cylinder itself. The door or flap C is then opened, and the coffee is or may be
removed into a cooler.
The apparatus may be constructed of any suitable dimensions, but for general
work we prefer to make the cylinder of a diameter of about one foot six inches to
two feet, and of a length of from four feet to six feet, according to the quantity
required to be roasted at each charge. An octagonal or hexagonal or other suitable
vessel may be used instead of a cylinder.
If instead of coffee chicory or cocoa is to be treated the apparatus would be used
in nearly the same way, merely altering the manipulation to such an extent as is
necessary in roasting by the ordinary process.
When used for substances which do not require actual roasting, but only drying,
the heat of the gas must of course be applied much more moderately, and the
apparatus worked for a much shorter time with each charge.
When large quantities of coffee or other substances are to be treated it is advan-
tageous to make the action of the apparatus continuous. This may be effected in
the following way-Instead of causing the cylinder A, A, to rotate on a horizontal
axis we raise one end of this axis so as to cause the cylinder to rotate in a position
forming a small angle with the horizontal. We prefer in this case to increase the
length of the cylinder, and even eight or ten feet is sometimes advantageous.
It will be evident that with the cylinder in this inclined position, and the ledges
or shelves D, D, D, D, lifting the coffee, the coffee if fed in at the highest end will
gradually and regularly travel to the other end of the cylinder as it rotates.
The continuous feed and discharge may be effected in the following way :—
We perforate the highest end of the cylinder with one or more suitable holes,
which if there is more than one are at a similar radial distance from the axis of
the cylinder. Exactly opposite to one of these holes when it is in its highest
position we put a plate or guard forming the mouth of a fixed hopper or shoot
through or into which the coffee is fed, and through which it is delivered
into the apparatus. At each rotation of the cylinder, or as often as any one of
these holes passes in from of the plate or guard forming the mouth of the hopper,
a quantity of coffee will be delivered into the rotating cylinder, but the supply will
be stopped when any one of the holes is not opposite to the mouth of the hopper.
The quantity of coffee so supplied will be regulated by the size of the holes or by a
suitable slide.
This arrangement is shewn by dotted lines in Figure 1, letter H, and one of the
holes is shewn in Figure 2, letter H'.

page_text: It is obvious that any other suitable feeding arrangement may be adopted, but
we prefer the one we have described.
The coffee that has been roasted is or may be allowed to escape from the rotating
cylinder by means of one or more holes J, J, which are large enough to allow it
to pass readily through, and which are forined in the side of the cylinder itself.
A spout or hopper, which is not shown in the Drawings, is or may be placed
underneath the rotating cylinder to collect the coffee which escapes from these holes
and conduct it to the cooler.
When working with the apparatus in this way, that is, by a continuous process,
we prefer that the holes B2, B2, and the wire gauze B3, B³, should not be continued
along the entire length of the axle B, B, but that the last portion of the length of
the cylinder through which the coffee passes should be free from the actual flame
of the gas, in order that the roasting of the coffee may be completed by the heat of
the cylinder itself and of the coffee.
The speed with which the coffee travels through the cylinder will obviously
depend on the degree of inclination which is given to it, and upon the speed at
which it is caused to rotate. We find in practice that a speed of thirty revolutions
per minute is a suitable one, and that the angle of inclination may be so adjusted
as to cause the coffee to be retained for from four to six minutes in its passage
from end to end of the cylinder.
-
The length of time which is necessary will vary with the character of the coffee
which is being roasted, and therefore one end or the other of the cylinder should be
capable of being raised or depressed so as to cause the coffee to pass through at the
requisite speed.
This modificatation of the apparatus is also useful for drying grains or seeds, in
which case it is desirable to give a greater inclination to the cylinder in order that
the substance to be dried may travel more rapidly through the apparatus.
The advantages of roasting by means of this apparatus are that the operation is
effected in a far shorter time that has hitherto been customary, and that the loss of
weight in the roasting process is much less than in the processes in ordinary use,
and that owing to the short time that the coffee is exposed to the heat the product
is of a much better quality.
The flame produced by burning petroleum gas mixed with air, or by passing air
through petroleum spirit may in some cases be advantageously substituted for the
flame of the atmospheric coal gas burner.
Having thus described the nature of our Invention, and the mode in which the
same is to be carried into effect, we wish it to be distinctly understood that we do
not claim the precise details hereinbefore described, except so far as they are
essential to the carrying out of our Invention, but that what we do claim as our
Invention is,―
The apparatus herein before described for roasting or drying coffee, chicory, and
other grains, seeds, or vegetable products, and consisting substantially of a perforated
cylinder capable of rotation, and having within a gas burner giving a flame free
from smoke, whether the said cylinder be used in a horizontal position, or in a
position inclined to the horizontal.
In witness whereof, I, the said Alfred Edward Bonser, have hereunto set my
hand and seal, this Eighteenth day of March, in the year of our Lord One
thousand eight hundred and eighty.
ALFRED EDWARD BONSER. (L.S.)