IMPROVEMENTS IN PRESERVING AND COOKING ANIMAL AND VEGETABLE SUB- STANCES, AND IN VESSELS, APPARATUS, AND APPLIANCES FOR THOSE PURPOSES
Year: 1873

page_text: PROVISIONAL SPECIFCIATION left by George Clark at the Office
of the Commissioners of Patents, with his Petition, on the 14th
May 1873.
I, GEORGE CLARK, of No. 10, Craven Buildings, Drury Lane, in the
County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN PRESERVING AND COOKING ANIMAL AND VEGETABLE SUB-
STANCES, AND IN VESSELS, APPARATUS, AND APPLIANCES FOR THOSE PURPOSES,"
to be as follows:-
This Invention which relates especially to the preserving of animal
and vegetable substances in closed vessels by the action of heat, but may
be made available to cooking purposes, has for its object certain
improvements in the methods and processes now or heretofore in use for
preserving or cooking food and also in vessels in which the said articles
are contained, as well as in apparatus and appliances conducive to
carrying out the operations of such preservation or cooking of animal
and vegetable substances.

page_text: The improvements above referred to and which constitute my said
Invention are 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 article to be preserved to a temperature 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 temperature 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 the duration of time or
degree of temperature in each case as both those conditions depend on
the nature of the substances treated and on the use to which they are to
be applied or the amount of cooking (if food) to which they are to bo
submitted; but as a general rule the time may vary from half an
hour to two or three hours, and the temperature from 220° to 280°
Fahrenheit. In each case experience must determine the one and the
other, and beyond naming the limits just mentioned I do not consider it
requisite to connect my said Invention with the duration of the processes
or the temperature at which they are to be conducted.
As I propose to effect the object of the said Invention by various
methods I will for the sake of correctness enumerate and describe the
improvements in which these methods consist.
The 1st improvement relates to the means of expelling air by means
of high-pressure steam from any preserving vessel and its contents by
adapting and fitting to the cover of such vessel a steam valve of which
the scat is soldered or brazed or otherwise fastened to the cover, 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 valve on the cover of the vessel to
a given pressure the temperature required inside the preserving vessel is
attained.
The 2nd improvement consists in the application and use of a false
bottom inside and raised above the bottom of any preserving vessel
for the purpose of generating high-pressure steam to act upon the
substance contained in the vessel by means of weighting the valve
fitted to the cover of the vessel which constitutes the aforesaid 1st
improvement.

page_text: The 3rd improvement has for its object to subject articles of food or
other substances contained in any vessel to the action of heat applied as
herein-after mentioned by closing such vessel hermotically, leaving no
orifice for the escape of steam, or if a valve be used as above described
in my 1st improvement to a pressure corresponding to the temperature
intended to be produced inside the vessel. In the latter case the valve
will be a protection against excessive strain from internal pressure; in
the former case that protection will be obtained by making the vessel in
its materials, form, construction, and joints of sufficient strength to bear
the internal pressure to which it is intended to be submitted in the
process of heating its contents in any of the ways herein mentioned or
referred to.
The 4th improvement consists in applying heat to any vessel con-
taining animal or vegetable substances to be preserved or cooked, by
placing such vessel in a dry hot chamber or oven heated to the required
temperature by means of a stove or flues, or hot air or water or steam
pipes or any other contrivance by which such chamber or oven can be
heated and kept at a certain temperature, or the preserving vessel may
be heated in a calcium bath in the manner practised and well known for
heating the contents of preserving vessels. I do not propose to use
a steam oven, which I am aware has been used and which would not
effect the objects attained by this 4th improvement as part of my said
Invention, the essential principle of this improvement being to carry
it into effect without any countervailing external resistance to internal
pressure inside of any such preserving or cooking vessel except the
strength of the vessel itself with or without the aid of weight or
mechanical pressure applied as herein-after described by and under
improvement No. 6.
The 5th improvement has reference to the destruction or displacement
of the germs of decomposition which may exist in any food preserving
vessel or in the contents thereof. It consists in an apparatus for passing
atmospheric air through an iron or other tube fixed in a stove or
furnace, or otherwise heated and kept at a suitable heat to destroy such
germs of decomposition by being imbedded in or in contact with ignited
fuel contained in the stove or furnace, or enclosed in a steam pipe or by
any other means which will effect the object of heating to the required
temperature the air to be passed through the said heating tube. One
end of this tube by means of a union joint or otherwise will be

page_text: connected with the pipe of a forcing air pump by which air is to be
passed into the heating tube and through it at a given pressure into
a pipe connected with the other end of the said heating tube, so that the
said vessel being connected by means of a union joint or flexible tube
or otherwise with the last named pipe, air in which the germs of
decomposition have been destroyed by passing through the heated tube
will be forced into and through the preserving vessel and its contents,
thereby expelling the air in such vessels which may contain any of such
germs and replacing it by air which has passed through the aforesaid
heated tube. This operation being accomplished the outlet for the exit
of air from the vessel may be closed by sealing the tube, and then the
vessel may be detached from the air pump, the hole in the vessel for
forcing air into it may be closed, and the vessel hermetically sealed at
both ends.
The 6th improvement is the application of weight or mechanical
pressure to the top and bottom of any vessel containing animal or
vegetable substances to be preserved by heat, so as independently of or
in addition to the strength of the vessel itself to resist and bear the
strain of internal pressure during the time the inside of the said vessel
is subjected to the high temperature described as a means of effecting
the said preserving process in the above mentioned 3rd improvement,
and I propose to enable such vessels to resist and bear such pressure by
a screw or any other mechanical appliance acting on the top and bottom
of the vessel as well as by placing a weight on the top of such vessel,
in such way that this protective external pressure may be readily and
promptly applied and removed. A material object & one of the
effects of this improvement is to be able to use thinner metal for food
preserving tins and thereby diminish the cost of such tins which adds
considerably to the prices of the contents.
The 7th improvement consists in covering any food preserving vessel
with a lid having a rim which being placed over the top of the body of
such vessel shall rest outside the body like a saucepan lid on a bead or
ledge round and near to the top rim of the body and in applying a
washer of felt or caoutchouc or any other suitable material, which by
means of pressure on the lid shall form an air and steam-tight joint
between the cover and the body of the vessel during the time the
process of preservation is in action, and until the vessel and its contents,
after such process is concluded, shall be cold, after which the lid is to

page_text: be secured to the body of the vessel, and the joint between these two
parts hermetically sealed by a band joint of metal or other suitable
material, or by other suitable means.
I have transferred to this present Provisional Specification such parts
of my Invention entitled "Improvements in Preserving Animal and
Vegetable Articles of Food, and in Vessels, Apparatus, & Appliances
for such Preservation," for which I obtained a certificate of Provisional
Protection, No. 3393, dated the 14th November 1872, as relate to the
application of a steam valve and false bottom to preserving or cooking
vessels as herein-before described and mentioned as the 1st and 2nd
improvements, but I do not comprise any other part of the improve-
ments described in the last mentioned Provisional Specification as part
of the Invention of which this is the Provisional Specification.
Any one or more of the improvements herein-before described as parts
of my said Invention may be used in combination with another or
others of them.