IMPROVEMENTS IN PRESERVING ANIMAL AND VEGETABLE ARTICLES OF FOOD, AND IN VESSELS, APPARATUS, AND APPLIANCES FOR SUCH PRESERVATION
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by George Clark at the Office of
the Commissioners of Patents, with his Petition, on the 14th
November 1872.
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 ANIMAL AND VEGETABLE ARTICLES OF FOOD,
AND IN VESSELS, APPARATUS, AND APPLIANCES FOR SUCH PRESERVATION," to be as
follows:-
This Invention which relates to the preserving of animal and vegetable
articles of food in closed vessels by the application of heat, has for its object
certain improvements in some of the methods and processes now or here-
tofore in use for that purpose, and also in the vessels in which the said
articles are contained, as well as in the appliances used in carrying out
the operations of such preservation. I therefore think it advisable to
give some account of the methods and processes referred to (now in use
or known) before describing my said improvements. I propose to adopt

page_text: the well known plan of placing the articles to be preserved in air-tight
vessels made of tinned iron, usually called tins, and expelling the
atmospheric air from such articles and vessels by means of heat, of
which the object is to raise the temperature of the contents of the said
vessels to 212° Fahrenheit, that is to say, the boiling heat of water, the
steam thus generated being allowed to escape from the tin through an
aperture in the cover thereof, this aperture being afterwards closed
and hermetically sealed when the preserving process is considered to be
completed, except that in some cases after the aperture is closed and
sealed the tins are again subjected to the action of heat.
In carrying out my said improvements in connexion with the said
methods and processes above described or referred to, any of the known
methods of heating may be employed, as for example a hot bath
of solution of muriate of lime, or a hot plate, or any other suitable
means.
Of the two modes of heating mentioned I give the preference to the
latter.
I wish it to be understood I do not claim any of the methods or
processes above mentioned or referred to as now in use and already
known.
What I claim as my said Invention is the improvements in and in
carrying out and more completely performing the said methods or pro-
cesses, and of those my said improvements the following is a description:―
Taking the aforesaid methods and processes as now practised or known
as applied to the preservation of meat, the essential condition they are
intended to accomplish so as to insure success is to produce a vacuum
in the vessel containing the meat by expelling the atmospheric air from
both by the application of heat. But this object is not always
attained, and generally meat preserved by this method is overcooked,
and sometimes unpalatable. These defects are the result of the mode of
heating the vessel either on a hot plate or in a calcium bath at a
temperature of from 240° to 280 degrees of Fahrenheit, and the com-
paratively small quantity of liquid in the tins whence it arises, that the
meat undergoes not a boil but a stewing and baking process, which over-
cooks and dessicates the meat. It is a mistake to conclude that the
object of applying heat is to cook the meat, that to some extent is a
necessary result, but the preserving principle in submitting meat or

page_text: other food to the action of heat in a close vessel is to generate steam,
which expels the atmospheric air from the articles to be preserved. The
decomposition of air inside a closed vessel by heat is also relied upon as
a preserving process, but this can only be effected at a high temperature,
which if too long maintained overcooks and deteriorates the articles of
food so treated.
Now the object of my said Invention applied to the preservation of
meat or other food in closed vessels having an aperture in the cover is
to generate or heat steam in such vessels in sufficient quantities to a
higher temperature than 212 degrees Fahrenheit, and apply this super-
heated steam as the means of expelling the air from the preserving
vessel and its contents, at the same time regulating the supply and
temperature of the steam applied, and the duration of the process by
mechanical appliances in the following way :—
Firstly. A false bottom is fixed inside and above the bottom of the
preserving vessel. This false bottom is made of metal or earthenware,
perforated with holes, or of wire gauze, and is supported at a suitable
height, say from ½, an inch to 2 inches above the true bottom, affording
space to contain enough water for the generation of steam required to
carry out the operations herein-after described or referred to, according
to the size of the tin.
Secondly. A moveable steam valve apparatus is provided for the
purpose of being placed over the steam escape aperture in the cover
of the vessel, and this apparatus is constructed as follows, namely, a
valve tube is made, say of ½, an inch diameter more or less, according
to the size of the vessel, with a spreading conical top serving as a cup
or seat for the valve which is ground into it. The valve has a shaft
underneath, which being slightly less in diameter than the tube works
freely in the latter and allows the escape of steam when the valve rises.
To regulate the pressure of steam by weighting the valve a vertical pin
is fixed on the head of the valve, on which pin weights having holes in
the centre may be securely held and readily placed or displaced as
required. The valve apparatus is fixed on a stand having a broad base
by means of which the valve tube is placed firmly over the aperture in
the cover of the tin.
Thirdly. In order to form a steam-tight joint at the bottom of the

page_text: plate of iron may be rivetted or soldered), both corresponding to the
diameter of the stand, is sunk in the cover of the tin around the steam
aperture, and an india-rubber or felt washer is placed in this recess, or
on the iron disc under the bottom of the stand.
Fourthly. The steam valve apparatus being placed in its position
over the aperture in the cover of the tin, with a compressible washer
under its bottom is held and pressed down so as to form a steam-tight
joint by some suitable contrivance, such as screw or spring pressure or
weight bearing on the foot or stand of the valve tube. For this purpose
I consider the following is a good plan:-I make a circular plate of 1
tinned iron of about the same diameter as the bottom of the preserving
tin; to this plate I fasten two stiff vertical metal straps running opposite
each other up the sides to the top of the tin with a short length to each
turned back horizontally at right angles outwards. To each of these
bent pieces I rivet a steel spring just the proper length that the ends 1
shall rest on the stand of the valve tube, and I give to each of these
springs a strength of pressure when lifted to its acting position equal.
to at least 2 lbs., or in lieu of springs I propose to rivet short bars of iron
of which the ends resting on the valve tube stand shall serve by means
of thumb screws to hold down the valve apparatus and form a steam- 2
tight joint, the projecting horizontal ends serving as handles to lift the
tin conveniently.
Another mode of securely fixing the valve tube on the cover of the
tin is to fasten by rivetting, soldering, or otherwise to the centre of the
cover a metal plate with a hole corresponding to the aperture in the 2
cover 1/8th to th of an inch thick, more or less, and of proper form and
size, a disc 2 to 3 inches in diameter being suitable. In this plate and
that forming the stand or foot of the valve tube, two or three female
screw perforations are made, those in the two plates corresponding
exactly in diameter, pitch and position, so that with thumb screws 3
corresponding to the female screws the two plates may be firmly
screwed to each other, and with a compressible washer placed between
them may form a steam-tight joint, any other plan of effecting the same
object may be applied.
ALL

page_text: supply tube of a vessel containing liquid gravy, gelatine, or fat, or water,
and to inject either of those fluids to fill any vacuum or space in the
tin if considered advisable in the manner herein-after described.
The mechanical arrangements and appliances above described and
the heating apparatus which I will assume to be a calcium bath heated
by steam pipes to 250° to 280° Fahrenheit being prepared and in
readiness to commence operations, these are carried out as follows :—
It being advisable that the tins should not be immersed too deeply
in this hot bath its temperature rising higher than 212 degrees, a stand
is placed in the bath at such a height that the immersion of the tins
standing on it shall not exceed 1 to 3 inches, more or less, from the
bottom of the tins, according to their size in order to protect the sides
of the upper part of the vessel against which the meat inside presses,
from contact with the superheated liquid of the bath. To regulate the
level of the hot liquid in the bath to the required height a ball cock
floating on the surface of the hot bath is connected with a supply tank
of boiling solution of muriate of lime.
The preserving vessel or tin being filled with meat from the false
bottom on which it rests to the top, leaving a space between the false
and true bottom, and enough water to fill that space being poured into
the tin, the cover having an aperture as before mentioned is fastened
on by soldering or otherwise. The vessel with the valve apparatus
well secured to it over the aperture in the cover is then placed in the
calcium bath and there left till the contents of the tin boil steam issuing
freely from the aperture and is so allowed to remain for 5 to 15 minutes
or longer according to the bulk of the meat under treatment. The valve
is now weighted sufficiently to raise the temperature of the steam inside
the vessel to about 5 to 15 degrees or more above that of boiling water,
the sufficiency of such increase of temperature to be determined by
experience. This superheated steam penetrates into the fibre and tissue
of the meat, bursts open the vesicles they envelope, raises the juices to
boiling heat, and issuing from the valve under pressure drives out or
carries with it all the air from the tin and its contents. A few minutes
will suffice for this operation without overcooking the meat. When it
is completed the vessel with its aperture still closed by the valve is
removed from the heating apparatus. Immediately after the tempera-
ture of the tin and its contents gradually lowers, the steam condenses,
and the valve preventing the entrance of air, a vacuum is formed inside

page_text: the vessel. At this moment (or afterwards if it is found by experience
it is preferable to allow the meat to become cold) the pipe fixed to the
valve tube which has been already described is connected with the pipe
of a vessel containing liquid gravy, gelatine, or fat or water, the stop
cocks of both pipes are opened and one or the other of those liquids t
supplied as may be deemed most suitable (for roasting meat fluid fat is
preferable) flows into the tin and fills the vacuum.
The preserving operation by the application of my said Invention if
properly conducted may now be considered as complete, but to effect the
expulsion of any air which might remain or have entered into the tin 1
after filling the vacuum as before described, it may be advisable to place
the tin in the hot bath and having brought the contents to the boiling
point close the aperture with the valve properly weighted so as to allow
the steam to escape for some minutes at a temperature above 212°.
°
When the final steaming process is accomplished the vessel being 1
removed from the heating apparatus, and placed on a table, the valve is
taken off and the steam allowed to escape freely for a few moments, after
which and whilst the steam is still issuing from the aperture a stopper
prepared to fit into the aperture having a metal disc at its top, and fixed
at the end of the valve shaft, or of an iron rod is thrust through the 2
valve tube into the aperture which is thus closed just as a bottle is
corked before any air can enter into the vessel. Simultaneously with
closing the aperture, or quickly after, a cold wet cloth is wrapped round
the tin, condensation commences inside the vessel, and pressure from
within ceases. The valve or iron rod which up to this time has served 2
to keep the stopper fast in its seat as well as the valve apparatus, are
now removed and the metal disc over the stopper being soldered down,
the tin of preserved meat is hermetically sealed.
:
To preserve meat in quantities I propose to manufacture cylindrical
iron casks of various sizes to contain 20 lbs. to 100 lbs. or more of 3
meat, and of sufficient strength to resist when hermetically closed,.
internal or external pressure of two atmospheres at the least. These
vessels are fitted with a false bottom in the way before described, and
closed with a cover fitting over and fastened to a flange round the top
edge of the vessel by means of screw bolts and packing so that the 3
vessel may be closed or opened by fastening or unfastening the screw-
bolts. I fill this vessel with joints and pieces of fresh meat which rests.

page_text: on the false bottom, and I pour into it a certain quantity of water for
the generation of steam; I prefer that previously to placing the meat in
the iron cask, the bones and all superfluous fat, skin, and gristle be
separated from it, and that it be steeped in a weak brine for twelve
hours, and perforated through and through with a steel skewer in many
places. I also prefer that the water placed in the vessel be distilled or
boiled and filtered. This vessel being filled with meat the cover is
fastened on it and made steam-tight. The cover has a steam aperture
over which a valve apparatus is secured in the manner already mentioned
and the vessel and its contents are subjected to the same operations for
the generation of steam and the expulsion of air as herein-before described,
with reference to tins containing smaller quantities of meat.
On this plan considerable quantities of preserved food may be trans-
ported with safety by sea or land. In order to diminish the expense
of.
packages, these being iron casks made as above described and of different
sizes to contain say 25lbs., 50lbs., 75lbs., and 100lbs. of meat and of
suitable dimensions, these variously sized packages will fit into each
other forming nests to be returned as empties to the place they come
from, and refilled with preserved meat. In this way the cost of packages
will be materially reduced as the return freight would be trifling. The
covers may be packed separately in crates or cases.
The same improvements above described for the preservation of meat
are applicable to poultry, game, fish, vegetables, fruits, and other articles
of food, with the modifications incidental to the nature and character
of each.
Meat in quantities might be first steamed in a cauldron and when
sufficiently heated, be cut into pieces, weighed, and put in the tins
to undergo the processes of my said Invention, as herein-before
described. Or it may be found convenient to steam the meat in
open tins with false bottoms and allow it to cool before fästening
on the cover, afterwards submitting the meat to the last process to
expel the air with superheated steam and fill the vacuum in the manner
already described.
"
The preserving vessel thus arranged is in fact a steam boiler
provided with a vent for the escape of steam and with a safety valve
to regulate the pressure. Instead of supplying water to the false
bottom for the production of steam as above described, steam may

page_text: be introduced into it from a boiler and the supply be regulated by
a stop-cock, but the generation of steam in the vessel itself will be
more convenient and simple, as it avoids a complicated arrangement
required by the other plan of steam pipes and connections which
must be fitted to each vessel and afterwards disconnected before a
preserving vessel can be attached, detached, and removed.
With reference to the dimensions and quantities mentioned in
describing the improvements of my said Invention I have stated those
I consider suitable for the performance thereof, but I do not confine
myself to those dimensions or quantities which may have to be varied :
under varying circumstances of adaptability and convenience.
By way of illustrating the nature of my said Invention it may be
observed that in the application of heat as a means preserving
meat or other food in close air-tight vessels the object is not to cook
the food but to expel the air from every part of the substance or tissue :
of the food to be preserved, as well as from the vessels containing the
same, by the action of the steam generated by the heating process.
In methods hitherto used for that purpose no provision is made to
employ superheated steam for the expulsion of air by any system which
insures and regulates or controls the generation of superheated steam,
according as each operation may require. Whereas by my said
Invention provision is made to effect those objects so as to a great
extent to render the mechanical contrivances employed self-acting.
In the arrangements for preserving meat on a large scale it is
well to observe that the bones and cartilagenous parts of the animal:
ought to be employed by boiling them down to produce gravy and
gelatine, to be used for the purpose of filling the preserving vessels
after the air has been expelled from and a vacuum is formed in.
such vessels by the processes and in the manner above described.
When the vessels of preserved meat are opened for use the gravy:
or broth contained in them may be reduced by boiling to a proper
consistency, to be served with the meat when boiled or roasted, or
to be cooked with it when stewed.