IMPROVEMENTS IN THE PRESERVATION OF MEAT AND ANIMAL SUBSTANCES
Year: 1867

page_text: LETTERS PATENT to Theophilus Redwood, of 39, Russell Square, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN THE
PRESERVATION OF MEAT AND ANIMAL SUBSTANCES."
Sealed the 14th January 1868, and dated the 15th July 1867.
PROVISIONAL SPECIFICATION left by the said Theophilus Redwood at
the Office of the Commissioners of Patents, with his Petition, on the
15th July 1867.
I, THEOPHILUS REDWOOD, of 39, Russell Square, in the County of Mid-
dlesex, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE PRESERVATION OF MEAT AND ANIMAL SUBSTANCES," to be as
follows:-
This Invention relates to certain modifications of methods of preserving
meat and animal substances by means of paraffin, for which Patents were
granted to me on the 10th and 23rd of November 1865 (Nos. 2892 and 3009),
and the objects of such modifications are twofold.
First, to cause the more speedy and efficient application of the temperature
required for the complete destruction of the germs of organic life in some of
the animal substances to be preserved. This modification applies to that part
of my process aforesaid which consists in heating animal substances, such as
fresh meat, in melted paraffin; I find it advantageous in doing this to immerse
the meat in paraffin contained in a strong vessel provided with an air-tight
cover securely fastened down, and then to raise the temperature of the paraffin
to 270° or 280° Fahrenheit, and to keep it at this temperature for about half

page_text: an hour, the steam generated from the juices of the meat being confined, so
that the temperature of the meat may be raised to the required point, after
which the heat is to be allowed to subside and the process completed in the
manner described in the Specifications of my former Patents.
Secondly, to ensure more perfect exclusion of air and protection from its
injurious effects by applying to the substances submitted to the preservative
process an additional external coating of a material less easily broken or
cracked or permeated by air than paraffin is, and it is preferred also that the
material of this coating should be of a transparent nature that the meat or
material it encloses may be freely seen through it. The material I use for
this purpose is gelatine, to which a portion of glycerine or sugar, or both
glycerine and sugar, or glycerine and gum, or sugar and gum, is added in such
proportions that the coating of such material when dried shall be more or less
flexible, and may by means of the glycerine be rendered elastic like india-
rubber. I have found a mixture prepared in the following manner to answer
the purpose-Dissolve six pounds of gelatine in from twelve to fifteen pounds
of water by the heat of a water bath, and add two pounds of glycerine, or one
pound of glycerine and one pound of sugar or gum, or one pound of sugar and
one pound of gum. The mixture thus prepared is to be applied while it is
kept fluid by heat, taking care that it is not hot enough to melt the paraffin,
which has been previously applied. The meat or other substances to be pre-
served having been treated in the manner described in the Specifications of
my Patents of the 10th and 23rd of November 1865, with the modification
already alluded to, are to be dipped into the gelatinous mixture, so that on
being taken out they shall retain a coating of the mixture, which will become
a tenacious solid as it cools, and will become harder and stronger when it has
dried on exposure to the air.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Theophilus Redwood in the Great Seal Patent Office on the
14th January 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THEOPHILUS
REDWOOD, of 39, Russell Square, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of July, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirty-first year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said

page_text: Theophilus Redwood, Her special licence that I, the said Theophilus Redwood,
my executors, administrators, and assigns, or such others as I, the said
Theophilus Redwood, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE PRESERVATION OF MEAT AND ANIMAL SUBSTANCES," upon the condition
(amongst others) that I, the said Theophilus Redwood, my executors or
administrators, by an instrument, in writing under my, or their, or one of
their bands and seals, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Theophilus Redwood, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:-
This Invention relates to certain modifications of methods of preserving
meat and animal substances by means of paraffin, for which Letters Patent
were granted to me on the 10th and 23rd days of November 1865, Nos. 2892
and 3009, and the objects of such modifications are twofold.
First, to cause the more speedy and efficient application of the temperature
required for the complete destruction of the germs of organic life in some of the
animal substances to be preserved. This modification applies to that part of
my process aforesaid which consists in heating animal substances, such as fresh
meat in melted paraffin. I find it advantageous in doing this to immerse the
meat in paraffin contained in a strong vessel provided with an air-tight cover
securely fastened down, and then to raise the temperature of the paraffin to
270° or 280° Fabrenheit, and to keep it at this temperature for about half an
hour, so that the steam generated from the juices of the meat being confined
the temperature of the meat may be raised to the required point, after which
the heat is to be allowed to subside, and the process completed in the manner
described in the Specifications of my former Patents.
Secondly, to ensure more perfect exclusion of air and protection from its
injurious effects by applying to the substances submitted to the preservative.
process an additional external coating of a material less easily broken or
cracked or permeated by air than paraffin is, and it is prefered also that the

page_text: material of this coating should be of a transparent nature that the meat or
material it encloses may be freely seen through it. The material I use for
this purpose is gelatine, to which a portion of glycerine or sugar, or both
glycerine and sugar, or glycerine and gum, or sugar and gum, is added in such
proportions that the coating of such material when dried shall be more or less
flexible, and may by means of the glycerine be rendered elastic like india-
rubber. I have found a mixture prepared in the following manner to answer
the purpose-Dissolve six pounds of gelatine in from 10 to 12 pounds of
water by the heat of a water bath and add two pounds of glycerine, or one
pound of glycerine and one pound of sugar or gum, or one pound of sugar
and one pound of gum. The mixture thus prepared is to be applied while
it is kept fluid by heat, taking care that it is not hot enough to melt the
paraffin which has been previously applied. The meat or other substances to
be preserved having been treated in the manner described in the Specifications
of my Patents of the 10th and 23rd of November 1865, with the modifi-
cation already alluded to are to be dipped into the gelatinous mixture, so that
on being taken out they shall retain a coating of the mixture, which will
become a tenacious solid as it cools, and will become harder and stronger
when it has dried on exposure to the air.
The following is the manner in which I prefer to operate in preserving
fresh meat-I employ a strong iron pan jacketted with high-pressure steam,
and provided with a cover which can be secured steam-tight by bolts and
nuts, or in any convenient way; into this pan I place the pieces of meat to
be preserved, each piece having a string attached to it by which it is handled
throughout the process; it is convenient that the meat should be in pieces
of about 6 or 8 pounds weight. The vessel contains sufficient paraffin to
cover the meat, and it should be nearly full. The cover is secured in its place
with a washer of vulcanized india-rubber, and high-pressure steam is admitted
to the jacket, and the contents of the vessel are thus heated to 270° or 280°
Fahrenheit, the temperature being indicated by a thermometer screwed into
the cover.
When the required heat is attained it is continued for about
an hour or for such time as will suffice for the heat to penetrate to the centre
of the meat, and the steam is then shut off from the steam jacket, and a cock
is also opened to relieve the pressure in the vessel. The cover is now
removed and the pieces of meat are quickly transferred with as little exposure
to the air as possible to a second vessel which is used for cooling the meat
and coating it with paraffin. This second vessel contains a solution of
common salt and nitre in water in the proportions of one part of nitre and
sixteen parts of common salt to 820 parts of water, which solution occupies

page_text: rather more than half of the lower part of the vessel, and the part of it near
the bottom is kept cool by means of cold water running through a coil of pipe
fixed to the inner surface of that part of the vessel. The upper part of the
vessel contains melted paraffin which floats on the surface of the saline
solution, and is kept at a temperature of about 140° or from that to 160°.
Fahrenheit by means of hot water or steam passing through a coil of pipe
similar to that already alluded to, which coil must extend downwards into
the part of the vessel containing the upper portion of the saline solution so as
to prevent any of the paraffin from being congealed by contact with the cold
saline liquid; there is thus a cold solution of salt at the bottom of the vessel
with a stratum of warm solution above, and over this the melted paraffin.
Before proceeding to use the saline solution for cooling the meat it must.
be boiled beneath the surface of the paraffin for the purpose of expelling air
and destroying any germs of organic life that it may contain, and if it bas
already been used and may contain some of the juices or other parts of the
meat it should be heated to about 280° Fahrenheit, this temperature being
attained under pressure by securing a cover to the vessel. After having thus
submitted the saline solution to the requisite beat it is to be cooled, as already
explained, while the melted paraffin on its surface protects it from further
contact with the air, and it can now be used in the process of cooling and
coating meat until it has been again exposed to air. Each piece of meat as it
is transferred from the hot paraffin bath to this second vessel is allowed to
sink to the bottom of the saline solution, and is left there until it has become
cold enough for the paraffin to be congealed on its surface; it is then drawn
up through the melted paraffin, a film of the latter being congealed on its
surface as it passes through it and is brought into the air. The coating thus
formed may be increased in thickness to any required extent by repeatedly
dipping the meat into the same or similar melted paraffin. Thus far the
process is similar in essential points to that described in the Specifications of
my Patents of the 10th and 23rd of November 1865, excepting that in the
first part of the process I now employ a close vessel in which the steam
generated from the juices of the meat is confined, so that the heat can be
raised to the required point without evaporating or concentrating the juices,
and that the saline solution is not so strong as that previously specified.
The next part of the process, and which is entirely new, consists in covering
the paraffin with an external flexible coating, such as I have already alluded
to for protecting the paraffin from being cracked or broken. For this purpose
I prefer to use the mixture of gelatine and glycerine which I have described;
this mixture with the proportion of water specified being melted by the

page_text: application of a gentle heat is to be kept at a temperature of about 100°
Fahrenheit, which is sufficient to keep it in the melted state, and care must
be taken not to allow it to become so warm as to melt the paraffin when the
meat with its coating of paraffin is put into it. The gelatine mixture is
applied by immersing the meat with its coating of paraffin, and suspended by
the string attached to it into the melted mixture, then immediately removing
the meat and hanging it in a cool place, so that the gelatine that has not run
off may become solid and form a compact and continuous coating over the
paraffin; this dipping may be repeated two or three times or oftener so as to
produce a coating of the required thickness. The pieces of meat thus coated
are now to be left suspended in a dry and moderately warm atmosphere until
all moisture has evaporated from the gelatinous coating, in which state it will
be hard, flexible, and slightly elastic; it will also be transparent and impervious
to air.
Fresh meat and animal substances that have not been previously sub-
mitted to any process capable of arresting putrefactive decomposition are
treated in the foregoing manner, but substances such as hams, bacon,
tongues, &c., which have been previously salted, may be preserved from the
injurious effects of exposure to the air by merely coating them first with
paraffin and then with the mixture of gelatine without subjecting them to the
preliminary operation of immersion in the hot bath of paraffin.
I sometimes find it advantageous to apply a concentrated cold solution of
bichromate of potash to the gelatinous coating, and to expose it afterwards to
the light, by which means the gelatine is rendered insoluble in water and less
liable to be affected by a damp atmosphere; this may be done by immersing
the pieces of coated meat in the solution of bichromate of potash for about
half a minute and then hanging it up to dry. After the coating has been
completed the strings may be cut off close to the surface of the coating,
and the exposed ends sealed by applying some of the gelatinous mixture to
them.
In witness whereof, I, the said Theophilus Redwood, have hereunto set
my hand and seal, this Eleventh day of January, in the year of our
Lord One thousand eight hundred and sixty-eight.
T. REDWOOD. (L.S.)