IMPROVEMENTS IN PRESERVING AND COOKING ANIMAL AND VEGETABLE SUBSTANCES, AND IN VESSELS, APPARATUS, AND APPLIANCES FOR THOSE PURPOSES."
Year: 1873

page_text: LETTERS PATENT to George Clark, of No. 10, Craven Buildings,
Drury Lane, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN PRESERVING AND COOKING ANIMAL AND VEGETABLE
SUBSTANCES, AND IN VESSELS, APPARATUS, AND APPLIANCES FOR THOSE
PURPOSES."
COMPLETE SPECIFICATION filed by the said George Clark at the Office
of the Commissioners of Patents, with his Petition and Declaration,
on the 30th October 1873, pursuant to the 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
CLARK, of' No. 10, Oraven Buildings, Drury Lane, in the County of
Middlesex, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS
IN PRESERVING AND COOKING ANIMAL and Vegetable Substances, and IN VESSELS,
APPARATUS, AND APPLIANCES FOR THOSE PURPOSES," and have petitioned Her

page_text: Majesty to grant unto me, my executors, administrators, and assigns,
Her Royal Letters Patent for the same, and have made solemn
Declaration that I am the first and true Inventor thereof.
NOW KNOW YE, that I, the said George Clark, do hereby declare
that the following Complete Specification, under my hand and seal,
fully describes and ascertains the nature of the said' Invention, and in
what manner the same is to be performed, in and by the following
statement:-
This Invention, which relates especially to the preserving of animal
and vegetable substances in closed vessels by the action of heat, but 1
may partly be made available for cooking purposes, comprises certain
improvements in the methods and processes now or heretofore in use,
and also, in, vessels in, which, the said substances are contained, as well
as in apparatus and appliances conducive to carrying out the said.
improvements, which for convenience of description I divide into parts 1
as follows:-
.
1st. An essential part of the aforesaid improvements is based on the
consideration that the principle of the preservation of articles of food and
other animal or vegetable substances by the action of heat is to raise the
temperature inside the vessel containing the articles to be preserved to
above 212° Fahrenheit for a period varying in duration according to the
weight or bulk of the contents of the vessel and the degree of heat
applied therein, that is to say, for a longer time in proportion to the
increase of the former, and a shorter time in proportion to the
augmentation of the latter. No precise rule can be laid down for
duration of time or degree of temperature in different cases as both
these conditions depend on the nature of the substances treatedand the
use to which they are to be applied, or the amount of cooking (if food).
to which they are to be submitted. But as a general rule the time may
vary from half an hour to two or three hours, & the temperature from
240° to 280° Fahrenheit. In each case experience must determine the
one & the other; and beyond stating the limits just mentioned I do
not consider it requisite to connect my said Invention with the duration.
of the processes on the temperature at which they are, to be. conducted.
2nd. As a means of carrying the aforesaid principle into effect I
propose to expel air by the action of high pressure steam from any food
preserving vessel and its contents by adapting and fitting to such vessel

page_text: a steam valve, of which the seat is soldered or brazed or otherwise
fastened to the cover or other part of the said vessel, as may be most
convenient, and to which valve a stem or other contrivance is fitted to
weight such valve, of which the action is of the same character as that
of the steam valve of an engine boiler. By weighting the said valve to
any given pressure the temperature required inside the said vessel is
produced. Or high steam pressure in any such preserving vessel may
be attained by perforating an aperture in the cover so minute that
steam generated inside the said vessel by external heat at a high tempe-
rature not being able to pass out of such vessel with sufficient rapidity
will rise to a corresponding high temperature. "
3rd. To facilitate the production of steam in any preserving or cooking
vessel I place a false bottom inside, and raised above the bottom of such
vessel.
4th. Another mode by which I propose to carry out the principle of
preservation by heat at a high temperature is to submit the substances
to be preserved to the action of heat in a preserving vessel hermetically
closed, and having no aperture for the escape of steam. To enable
preserving vessels so arranged to bear high internal pressure those of the
smaller sizes may be made sufficiently strong in their materials, form,
construction and joints. But more effectually to protect preserving vessels
from the effects of internal pressure under the conditions above referred
to I apply weight or mechanical pressure externally in the manner most
appropriate to accomplish the object in view, but by preference to the
top and bottom or either of any such vessel and in such way that this
protective external force may be readily and conveniently applied and
removed.
It is obvious that for the said purpose many modes of adapting screw
pressure or other mechanical force or resistance including hydraulic and
steam power may be adopted.
I have arranged one mode which is represented in the Sheet of
Diagrams hereunto annexed.
Fig. 1 is a plan; Fig. 2, a longitudinal sectión; and Fig. 3 an end
elevation of a pressure box of iron plate of a size to contain any con-
venient number, say sixteen two pound preserving tins in two rows of
four tins at the bottom, and two rows of four tins standing on the former
with compressing appliances so arranged that the box may be used for

page_text: the two bottom rows only or for the four rows. To the two ends and
bottom of this box are fitted and rivetted two sets of bars of iron, of
which the uprights rise a little above the top edge of the box. These
upright bars on each side have slots in them a little above the top of the
position of the lower and upper rows or tiers of tins, these slots being
arranged to receive in each set of the upright bars the ends of a strong
iron horizontal bar, which being fitted into these slots and provided with
screw holes. Screws passing through such holes are screwed down
on an iron plate lying on the top of the tins of the lower or the lower
and upper rows together contained in the box, as the case may be. This
combination. forms a strong compressive and resisting force acting on
the top and bottoms of the said rows of preserving tins, and is convenient,
the aforesaid pressure box being moveable with the tins in it under the
required pressure.
In the annexed Diagrams (Figs. 1, 2, 3,) before referred to (a, a,) are
the front and back sides; (b, b,) the side ends; (d, d,) are the slots in
the upright bars (c, c); (e, e,) are the compressing bars, of which when
in use the ends are fitted and fixed in the slots (d, d), and have screw
holes in them through which the screws (f. f) pass, and are screwed
down to the top of the plate (g), which rests on the top of the preserving
vessels (h, h), shewn standing inside the box, Figs. 1, 2.
·
In some of the Diagrams a pressure box containing meat preserving
tins is shewn in position inside the oven.
A tray with a bottom and side ends arranged and constructed on the
same plan as the above described pressure box without back or front
sides may be usefully substituted for such box.
5th. I apply heat to any closed vessel hermetically sealed and con-
taining animal or vegetable substances to be preserved by placing such
vessel in a dry hot chamber or oven heated to the required temperature
by means of a furnace or flues, or hot air, or hot water, or steam pipes,
or gas, or any other contrivance by which such chamber or oven may
be heated and kept at a certain temperature; or the preserving vessels
may be heated in a calcium bath in the manner practised and well
known for heating the contents of food preserving vessels; but I do not
propose to use free steam in any oven or in any chamber containing food
preserving vessels for the purpose of supplying external pressure to such
vessels, as that plan would not effect the object of my said Invention,

page_text: although I may apply steam in an oven or chamber for heating such
vessels.
In the annexed Sheet of Diagrams Fig. 1ª is a plan; Fig. 2ª, a cross
section; Fig. 3*, a horizontal section; Fig. 4, a front elevation of the
oven. (ii) is the iron body of the oven resting on a fire-brick
foundation and lined inside and out with fire-bricks or clay; (j,j,) are
flues running from the front to the back and under the oven containing
gas pipes (k, k,) and serving for the supply of air, which being heated
by the gas flames passes into and through the oven in a serpentine
direction, as shewn by the arrows; (1) is an upright flue, into which the
hot air ascends from the flues (j, j); (m) is an iron plate placed on the
top of the pressure box and over the upright flue (1), of which it closes
the top. The iron plate (m) is made air-tight by means of felt or other
packing at the back and two sides of the oven, but with an opening (n)
in the front through which the heated air which has passed through the
oven proper (o) (containing the preserving vessels) continues its course
through the horizontal space (p) between the iron plate (m) and the
bottom of the cover of the oven, and issues therefrom through the outlet
pipe or flue (9); (7) is the cover fitting closely on and into the top of
the oven.
The cover is made air-tight by means of felt packing, and
has handles (8, 8,) to lift it on and off the oven, or for that purpose the
cover may be fitted with hinges; (t) is a thermometer to indicate the
temperature inside the oven, which is regulated by a damper in the
outlet pipe (9), and by raising or lowering the gas jets.
A feature of novelty of this arrangement of an oven is the triple
serpentine current of hot air circulating in and through it in the manner
above described.
In lieu of heating air by means of gas in the manner above described
air heated by other means may be made to enter into flues under the
bottom of the oven, and flow through and out of the oven in a similar
serpentine current, so that with the exception of using another mode of
heating the plan of the oven would be the same.
Instead of opening an oven so constructed as above described at the
top it may be hermetically closed at the top and have a door in the
front for feeding and drawing it.
To facilitate those operations I propose to place rails on the floor of
the said oven from the front to the back, and run on them a moveable

page_text: platform or truck on wheels, on which truck the preserving tins or other
vessels may be run into and out of the oven with facility and dispatch by
placing in front of the door of the oven, when open, a suitable platform
or table with its surface on the same level as that of the oven floor, and
provided with rails corresponding to those inside the oven.
Any one or more of the improvements herein-before described as parts
of my said Invention may be used separately or in combination with
another or others of them.
Having described the nature of my said Invention, and the manner in
which the same is to be performed, I wish to explain that I do not
claim generally or absolutely the preservation of animal or vegetable
substances in hermetically closed vessels by the action of heat, as I am
aware such preservation has been effected partially in respect of the said
substances in a partly cooked or preserved state, and has been attempted
I believe by enclosing hermetically sealed vessels containing animal or
vegetable substances in a steam and air-tight vessel or oven heated by
free steam or hot water or any other gas or fluid exercising pressure
externally on the said hermetically sealed vessels. But referring to the
explanation in the foregoing, first part of this Specification I wish it to
be understood that what I do claim in respect of that part of my said
Invention, and further explained in part 4 of this Specification is the
preservation of animal and vegetable substances enclosed in hermetically
sealed vessels, and preserved substantially as described in the said part 4
of this Specification, such vessels being heated by any of the means
herein-before mentioned, but without external pressure on the said food
preserving vessels arising from compressed steam or water or any gas or
fluid used for the heating process.
I also claim the application of mechanical pressure or resistance to
hermetically closed vessels containing animal or vegetable substances to
be preserved during the time the contents of such vessels are undergoing
the process of preservation by the action of heat, for the purposé of
protecting such preserving vessels (by means of such external mechanical
pressure or resistance) from the effects of internal pressure arising from
steam generated inside such vessels by the heating process employed,
the whole substantially as herein-before described or referred to.
I likewise claim the use of a valve applied and having its seat fastened
to any food preserving vessel, and of a false bottom placed inside any

page_text: such vessel, on the plan and for the purposes explained in parts 2
and 3 of this Specification, and relating to such valve or false bottom
respectively.
And I moreover claim the use and plan and right of construction of
any pressure box or oven made as described and explained respectively
in parts 4 and 5 of this Specification of my said Invention, and the
Diagrams thereunto annexed.
I also claim the use and application to cooking purposes of any part
or parts of my said Invention as may be available for such purposes.
In witness whereof, I, the said George Clark, have hereunto set my
hand and seal, this Thirtieth day of October, in the year of our
Lord 1873.