IMPROVEMENTS IN PRESERVING ANIMAL SUBSTANCES POR USE AS FOOD.
Year: 1868

page_text: LETTERS PATENT to James Dewar, Doctor of Medicine, residing at
Kirkcaldy, in the County of Fife, in North Britain, for the Inven-
tion of "IMPROVEMENTS IN PRESERVING ANIMAL SUBSTANCES POR USE AS
FOOD.".
Sealed the 31st March 1868, and dated the 4th February 1868.
PROVISIONAL SPECIFICATION left by the said James Dewar at the
Office of the Commissioners of Patents, with his Petition, on the
4th February 1868.
I, JAMES DEWAR, Doctor of Medicine, residing at Kirkcaldy, in the
County of Fife, in North Britain, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN PRESERVING ANIMAL SUBSTANCES FOR
USE AS FOOD," to be as follows:-
This Invention has for its object the preservation of animal substances
for use as food by the action of sulphurous acid in combination with
subsequent desiccation.

page_text: By desiccation I mean such desiccation as while securing that the
moisture is expelled from the substance to be preserved leaves in it the
essential constituents of the natural juices without destruction of their
soluble property.
By my Invention I first prepare the substances to be preserved by
soaking them for a longer or shorter time, depending upon their bulk
and consistency, in a strong aqueous solution of sulphurous acid, and I
thereafter subject the the substances so prepared to a process of thorough
desiccation, so as to expel as completely as possible all moisture from
them. Substances so treated with sulphurous acid and then desiccated
will remain in good preservation for a considerable period of time.
Moisture can be restored when wished by soaking the desiccated sub-
stance in water before it is used for food.
In some cases I grind the desiccated substance and mix it with
farinaceous matter.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Dewar in the Great Seal Patent Office on
the 31st July 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
DEWAR, Doctor of Medicine, residing at Kirkcaldy, in the County of
Fife, in North Britain, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourth day of February, in the
year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-first year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said James Dewar, Her special licence that
I, the said James Dewar, my executors, administrators, and assigns, or
such others as I, tho said James Dewar, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time, and at all times thereafter 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 PRESERVING ANIMAL
SUBSTANCES FOR USE AS FOOD," upon the condition (amongst others)

page_text: that I, the said James Dewar, or my executors or administrators, by
an instrument in writing under my, or their, or one of their hands
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 James Dewar, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement :-
This Invention has for its object the preservation of animal substances
for use as food by the action of sulphurous acid in combination with
subsequent desiccation.
By "desiccation," as used in this Specification, I mean such degree of
desiccation as while securing that the moisture is expelled from the
substance to be preserved, leaves in it the essential constituents of the
natural juices without material loss of their soluble property. The
property in sulphurous acid of preserving animal substances from decay
has been long known, but until recently no effectual and useful mode
of applying that property to the preservation of such substances for food
has been ascertained and made known. This has probably arisen from
Inventors having been afraid to make use of a sufficiently strong solution
of the acid, or to expose the substances sufficiently to its action, under
the notion that to employ a solution of the acid strong enough and for
a sufficient length of time to secure the desired result, would render the
substances unsuitable for food or disagreeable to the palate. This
apprehension I have ascertained to be ground groundless, and I have
employed a much stronger solution of the acid and exposed the sub-
stances to be preserved to the action of that acid solution for a sufficient
length of time to secure the desired result.
This improvement in applying the preservative property of the acid I
have explained in the Specification filed by me in relation to Letters
Patent granted to me by Her Majesty, and dated Second August One
thousand eight hundred and sixty-seven. I have however discovered
that if the substances (eggs of course being excepted) intended to be
;

page_text: preserved are treated in the first place in the manner mentioned in that
Specification, and are then subjected to desiccation, this combination of
means forms an effectual and improved method of preserving substances
for food.
The nature of my present Invention consists in combining the process
of desiccation with the process of treatment with sulphurous acid.
The manner in which my Invention is to be performed is as follows:-
The sulphurous acid to which I subject the substance intended to be
preserved is an aqueous solution of the ordinary commercial strength,
say, of specific gravity 1.012, which solution may be diluted with water,
or may be used without dilution, as herein-after mentioned. When
water is used for diluting the acid I find it best to employ water
distilled or recently boiled and allowed to cool.
For preserving birds, fish, and other animals I proceed as follows:-
The feathers of birds and the skins of other animals (except fish, from
which I do not remove the skins) are taken off, all viscera are removed,
and the substance to be preserved is thoroughly cleansed from impurities.
The bodies of animals thus prepared may be preserved without being
divided into joints or pieces; but in the case of larger animals I divide
them for convenience into suitable pieces.
In the case of shell fish, such as lobsters, crabs, and prawns, the fish
may be preserved with or without their shells. In the case of oysters
and such like shell fish I remove the shells. I immerse the substance
intended to be preserved in the solution contained in a case, cask, jar,
or other vessel, and allow the substance to be well soaked in the acid
liquor, that is to say, for a period varying from under one to about
twenty-four hours, according to the size of the substance immersed.
For example, a beef steak would require about an hour; a larger
substance would require a longer immersion in proportion to its bulk
and solidity. A very small substance, such as an oyster, prawn, or
whitebait, need not remain immersed longer than a few minutes.
The liquor in which the substances are immersed may according to
my Invention consist of the said solution of sulphurous acid of specific
gravity about 1·012 diluted to the extent of three parts of water to one
part of the said solution; but I prefer to use a stronger acid liquor,
namely, equal parts of the solution of the strength before indicated and

page_text: of water. The solution of the said strength may be used without
dilution, but the liquor in equal proportions of the solution of that
strength and water is more economical and quite sufficient.
After immersion, as above described, I subject the substances so
prepared to a thorough desiccation so as to expel the moisture. This
I find is best effected by subjecting the substances to a draught of warm
dry air varying from 80 degrees to 140 degrees of Fahrenheit. I prefer
a heat of about 135 degrees. For this purpose I hang the substances
in a chamber, through which warm dry air is made to pass, or lay them
on an artificially heated stove, or in an oven, or simply dry them by
laying or hanging them in front of a fire of coal, wood, coke, or
charcoal.
Other methods may be used for exposing the substances to the action
of dry air; but whatever mode be adopted care must be taken not to
carry the process of desiccation so far as to render the albuminous juices
of the animal substance entirely insoluble in water as their nutritive
qualities might be thereby much injured.
The substances should be desiccated with as little delay as practicable
after immersion in the liquor above mentioned. After being desiccated
they should be carefully kept dry until about to be used. Practically.
this may be attained by hanging them in an ordinary kitchen in which
a fire is burned.
The substances treated with sulphurous acid and then desiccated as
above described will remain in good preservation and suitable for use
as food for a long time.
I find it a useful and convenient plan to grind the substance preserved
according to my present Invention, and to mix it with farinaceous
matter.
To prepare the substances preserved according to my present Invention
for use as food they may if desired (altho' this is not indispensable) be
soaked in pure water so as to remove all traces of the acid (which will
however have to a considerable extent separated itself from the substance
during the process of desiccation), and to restore the moisture to them
if this be desired, they are then ready for being cooked.
I also find that if the substance preserved according to my present
Invention be ground into a powder, it may be conveniently used in that
form for soup, or if mixed with bread or potatoes may be used as

page_text: pudding, or if mixed with boiled potatoes, or wheaten flour, or meal
may then be made into biscuits. In the case of fish any bones (but
not shells) forming part of the preserved substances may with advantage
be ground up along with the rest of the preserved matter.
The grinding and other modes of dealing with the substance after
it has been preserved according to my present Invention do not form
any part of that Invention but are merely indicated as convenient ways
of keeping and using the substance so preserved.
In witness whereof, I, the said James Dewar, have hereunto set
my hand and seal, this Twenty-ninth day of July, in the year
of our Lord One thousand eight hundred and sixty-eight.
JAMES DEWAR. (L.S.)