CERTAIN IMPROVEMENTS IN THE APPLICATION OF HEAT TO THE PREPARATION, DESICCATION AND PRESERVA-
Year: 1847

page_text: DAVISON AND SYMINGTON'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ROBERT
DAVISON, of New Broad Street, in the City of London, Civil Engineer, and
WILLIAM SYMINGTON, of the same place, Civil Engineer, 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 Sixth day of November
(One thousand eight hundred and forty-seven), in the eleventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us, the
said Robert Davison and William Symington, our exors, adiñors, and assigns,
Her especial licence, full power, sole privilege and authority, that we, the
said Robert Davison and William Symington, our exors, admors, and assigns,
or such others as we, the said Robert Davison and William Symington,
our exors, admors, 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
Jersey, Guernsey, Alderney, Sark, and Man, and in all Her said Majesty's
Colonies and Plantations abroad, our Invention of "CERTAIN IMPROVEMENTS IN
THE APPLICATION OF HEAT TO THE PREPARATION, DESICCATION, AND PRESERVA-

page_text: TION OF BREAD STUFFS, CONFECTIONARY, PULSE, MEATS, VEGETABLES, AND OTHER
EDIBLE SUBSTANCES;" in which said Letters Patent is contained a proviso that
we, the said Robert Davison and William Symington, or one of us, shall
cause a particular description of 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, to be inrolled in
Her said 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.
NOW KNOW YE, that in compliance with the said proviso, we, the said
Robert Davison and William Symington, do hereby declare that our said
Invention consists partly of improvements in a certain method or methods of
drying, seasoning, and hardening wood and other articles, which are also
applicable to the desiccation of vegetable substances "generally," for which
former Letters Patent for England and the Colonics were granted to us on the
Twenty-sixth of March, One thousand eight hundred and forty-four, the dis-
tinguishing feature of which method or methods is the application of rapid
currents of heated air to the purposes aforesaid, and partly of certain other
and new modes or methods of applying heat to the preparation, desiccation,
and preservation of edible substances; and we declare that the nature of these
improvements, and the manner in which the same are to be or may be per-
formed, are fully described in and by the present Specification thereof, reference
being had to the Drawings hereunto annexed.
Firstly, our present Invention has relation to the apparatus for generating
heat of the various degrees required for the purposes of our said Invention.
In the Specification of our former Letters Patent we directed that atmospheric
air should be heated by causing it to pass through a series of pipes exposed to
the heat of a furnace, in the various ways as represented in Figures 1, 2, 3,
and 4, of the Drawings hereunto annexed, that is to say, that it should be first
conveyed from a supply pipe A into a pipe B₁ leading along one side of the
furnace, and be conveyed thence by transverse pipes C, C, of a horseshoe or
other convenient form, carried over the top of the furnace into a second horizontal
pipe B on the opposite side, whence it was to be transmitted by a pipe D to
the place containing the articles to be dried, desiccated, seasoned, or hardened.
Frequent inconvenience being experienced from the temperature of the air
fluctuating during the operation, we now add a regulator, by which the tempera-
ture may be adjusted according to circumstances. We effect this by connecting
the delivery pipe D near to its termination with the cold-air supply pipe A,

page_text: by means of a branch pipe K, the communication with the two pipes D and K
being opened or closed by a valve L, as it is acted upon by a mercurial
guage M, which is separately represented in Figure 5. The guage (M) is
connected in the manner shewn to the spindle valve (L), so that supposing the
guage to be adjusted to any given maximum of temperature (which must be
done by repeated trials), may rise in the mercury beyond that temperature, will
cause the valve to open to a corresponding extent, and admit a supply of cold
air to reduce the temperature to the required maximum. L' is a hand regu-
lator, for occasional use in admitting a supply of cold air into the delivery pipe
when the mercurial guage happens not to be in operation.
Secondly, our present Invention consists of an improved construction of
oven for applying rapid currents of heated air to the preparation or baking of
bread stuffs, confectionary, meats, and other edible substances usually pre-
pared in ovens or drying or hot chambers. According to the present and
common method of baking in an oven, the oven is first heated by the direct
application of fire to the interior, after which the fire is withdrawn, and the
bread or other material or substance to be baked is introduced. One un-
avoidable and evil consequence of this mode of proceeding is, that the interior
of the oven always retain on its surface more or less of the products of com-
bustion (always of an uncleanly and often of a pernicious character), which
act injuriously on the bread or other material or substance being baked.
Another evil consequence resulting from the common mode of baking in an oven
is, that the oven cannot be kept for howsoever short a period at an equal and
uniform heat, the heat gradually decreasing after the drawing of the fire.
Both these evil consequences are obviated by the improvements embraced
under this head of our present Invention. Instead of heating the oven by the
direct application of fire, we heat it by passing through it currents of air
heated by the means herein-before described or referred to, to any degree
required, and when the oven has been thus raised to the required température,
we shut off the currents, and leave them to circulate through passages or flues
made in the walls of the oven, and we attach to these passages or flues valves
or dampers, whereby we can keep up or diminish the temperature at pleasure:
Only pure and unvitiated air is thus suffered to enter into the oven or come
into contact with the material or substance in process of baking, and we are
enabled to keep that air at any degree of temperature which the operator may
find best suited for the purpose, and where materials or substances not
requiring so high a degree of heat are required to be operated upon, or which
it may be desirable to keep separate, we erect a chamber over or immediately
adjoining the oven. A sectional elevation of an oven, with a chamber above

page_text: it, on this improved plan, is given in Figure 6. E is the oven; F, a chamber
placed immediately above the oven for the purpose of containing such material
or substances not requiring so high a degree of heat for their preparation as
those placed in the oven, or which it may be desirable to keep separate.
G, G¹, G, G¹¹¹, G, G; are the passage or flues into and throngh which
the hot air flows to the oven and the chamber above it from the discharge
pipe D of the heating apparatus before described. H. is an iron plate, which
is placed immediately over the top of the first vertical air flue G, in order to
deflect the air into the horizontal flues (G¹, G¹), and prevent its acting too
powerfully against the centre of the floor of the oven (E). Ga, Ga, are
apertures in the side of the oven (E), through which the heated air is admitted
in the first instance into the interior. E¹ is a vent pipe, which leads from the
top of the oven through the air passage G, passes up the centre of the
chamber F, and is carried through the roof; which vent pipe serves to carry off
any impure vapours which may exhale from the materials or substances placed
in the oven.
I, I, are dampers to the apertures Ga, Ga, and I, a damper to
the vent pipe E, all of which are attached to spindles which pass out through
the external wall of the oven, and are worked by hand.
I is a damper or
valve to the flue G, which is suspended from balance weights by means of
chains carried over pulleys attached to the outside of the vent pipe E¹. M is
another vent for the escape of the used or vitiated air from the upper chamber
F, which may be opened or closed as required by means of a damper I¹¹¹,
worked by a chain or rope N from below.
A modification of this oven, which may be useful in some cases, is repre-
sented in Figures 7 and 8. The principal difference between this oven and
that before described consists in the floor of the oven being made to rotate,
whereby there will be a greater certainty of the materials or substances placed
upon it being equally heated, and whereby also their removal from the oven
will be greatly facilitated. This is effected by means of a circular rack R
attached to the bottom of the floor, into which a pinion P gears, which may be
worked from the outside by hand or any other suitable power. The upper
chamber F shews the way in which the space may be economized, by using a
number of trays or shelves S, S, for holding the articles placed therein for
drying or desiccating.
Thirdly, our present Invention consists of an improved apparatus for the
application of heat to the preparation, or, as it is sometimes denominated,
roasting of coffee, and of other substances, such as chicory, cocoa, barley, when
used for coloring purposes, in brewing, &c., requiring similar treatment.
A sectional elevation of this apparatus is represented in Figure 9, and a plan

page_text: of it on the line a, b, in Figure 10. T, T, are two revolving cylinders, mounted
parallel to one another in a suitable casing, which, like those of the coffee-
roasting apparatus described in the Specification of our former Patent, are
perforated all over with small holes for the admission of the heated air. In
the sides of each cylinder there are a number of cavities or recesses of a
U form, which are perforated like the rest of the circumference, and serve to
introduce the heated air more effectually into the interior; and in order that
the berries may not rest on the exterior of these cavities, but move about
freely within the cylinder, the cavities on one side are placed skew-wise in
relation to those on the opposite side (see Figure 10); each cylinder is covered
lengthwise by a close semi-cylindrical cover W, which is formed of two plates,
with charcoal dust or some other non-heat-conducting substance inserted
between them, and in each cover there is a valve or door d, through which
access may be had to the door of the cylinder for the introduction of the
coffee, and also an aperture a' for the escape into the vent pipe W¹ of any
noxious vapors which may exhale from the coffee in the first stages of its
preparation, and before its aromatic properties begin to develope themselves,
which last-mentioned aperture (d¹) is opened and closed by means of a
damper d. The coffee or other contents of the cylinder is discharged from
the cylinder down an inclined plane or shoot z, which obviates the necessity of
shifting the cylinders for the purpose of discharging, and allows the cylinders
to remain permanently in their places. At the lower extremity of the shoot
there is a shutter or valve Z', to prevent any escape of the heated air when
the shoot is not in use. The means of giving rotation to the cylinders are
similar to those made use of in the apparatus described in the Specification of
our former before-mentioned Patent. X is the passage for the inlet of the
heated air. to the two cylinders, and Y is a slide by which the air is admitted
or shut off at pleasure.
Fourthly, our present Invention consists of improved methods of applying
rapid currents of heated air to the desiccation or preservation of vegetable
substances. If the substances are of large bulk, such as carrots, turnips,
parsnips, &c. (but excepting always potatoes), we first wash them, then scrape
them, when necessary, next cut or slice them by hand or by any suitable
machinery, and then lay them in thin layers upon trays (with hair-cloth or
lattice-work bottoms), and place these trays on racks one above another in the
heating chamber.
When thoroughly desiccated they may be then either put
up in packages, or previously to packing be reduced to a very comminuted
state, and in either case it is desirable that the packages should be made
air-tight. To preserve potatoes, we prefer first to boil or steam them, then to

page_text: peel them, and afterwards to wash or otherwise reduce them to a state fit for
spreading in thin layers upon trays of the same description as those employed
in the preceding process. We then expose these trays with the substance or
material to impelled currents of heated air, as before described, at a tem-
perature of about one hundred and fifty degrees Fahrenheit, till the substance
or material is thoroughly desiccated. If the substances or material are of
small size, such as pulse, peas, or beans, we expose them in their entire state
to the rapid currents of heated air.
Fifthly, our present Invention consists of an improved method of applying
rapid currents of heated air to the preservation of meats. We find it most
convenient first to cut the meat when bulky into slices of about half an inch
thick, and hang these slices on lines or rails, where we expose them to rapid
currents of heated air. The temperature we find most suitable is from one
hundred and twenty degrees to one hundred and sixty degrees, but it should
not much exceed the latter degree. All moisture is by this means completely
expelled from the meat, and its albumen at the same time firmly coagulated.
Meat which has been so treated will continue for a long time, under ordinary
circumstances, in a perfectly wholesome state, but if intended to be exported
to damp or variable climates, we recommend that it should be treated with a
little highly diluted pyroligneous acid or some other approved antiseptic, to
prevent it from reimbibing humidity, and after which it should be subjected
to a further heating in order to free it from any moisture which the acid or
other antiseptic may have imparted to it. To ascertain when the meat has
been perfectly dried a portion of it may be weighed at intervals, and when
it ceases to show any diminution of weight the process may be deemed,
complete.
Sixthly and lastl, our present Invention consists of an improved method of
applying heat to the preservation of the edible matters contained in eggs. We
first strip the eggs of their sheels, then intimately mix together the yolks and
whites, next add about an equal weight of wheaten flour, ground rice, or other s
farinaceous substance, and beat up the whole into an uniform mass, which we
spread upon trays (with horse-hair cloth or lattice-work bottoms), and then
expose the mass so spread out to a témperature of about, but not much
exceeding, one hundred and eighty degrees Fahrenheit (whether the heat is
applied in rapid currents or not, is in this case a matter of indifference); when s
thoroughly dried the mass is reduced to the state of flour, and in that state
packed up for use. Or instead of thus mixing up the yolks and whites of the
eggs together, we preserve them separately, following the same process in
regard to the mixing of each with flour or other farinaceous substance, and

page_text: then desiccating the compound mass, as has just been described. Or instead
of adopting either of the preceding processes, we desiccate the eggs in their
entire state (denuded only of their shells, or the yolks and whites separately,
and then reduce them to a state of flour, without any intermixture with other
substances.
And having now described the nature of our said present Invention, and in
what manner the same is to be performed, we declare that the improvements
which we claim as constituting our said Invention are as follows:-
First, we claim the addition to the delivery pipe D of a branch cold air pipe
and mercurial guage and valves, as herein-before described.
Second, we claim the improvements in ovens whereby the same are heated
by rapid currents of heated air (instead of to the direct application of fire), as
before described.
Third, we claim the improvements in apparatus for preparing or roasting
coffee and other substances or materials requiring similar treatment, as before
described, in so far as regards the form of the cylinders and the arrangements
for keeping the same permanently in their places during the discharging of
the same.
Fourth, we claim the improved methods of applying rapid currents of
heated air to the desiccating or preserving of vegetable substances, as before
described, and the improved method of applying rapid currents of heated air to
the preservation of potatoes, as also before described.
Fifth, we claim the improved method of applying rapid currents of heated
air to the preservation of meat, before described.
Sixth and last, we claim the methods before described of preserving the
edible portions of eggs, whether the heating is effected by rapid currents of air
or in any other mode or manner.
In witness whereof, we, the said Robert Davison and William Symington,
have hereunto set our hands and seals, this Sixth day of May, in the
year of our Lord One thousand eight hundred and forty-eight.

page_text: AND BE IT REMEMBERED, that on the Sixth day of May, in the year
of our Lord 1848, the aforesaid Robert Davison and William Symington
came before our said Lady the Queen in Her Chancery, and acknowledged
the Specification aforesaid, and all and every thing therein contained and
specified, in form above written. And also the Specification aforesaid was
stamped according to the tenor of the Statute made for that purpose.
Enrolled the Sixth day of May, in the year of our Lord One thousand
eight hundred and forty-eight.