An Improved Process and Apparatus for Preserving Eggs!
Year: 1898

page_text: Date of Application, 23rd Aug., 1898
Complete Specification Left, 11th May, 1899-Accepted, 17th June, 1899
(Communicated from abroad by CARL REINHARDT, of Kaiserslautern, in the
Empire of Germany, Chemist.),
An Improved Process and Apparatus for Preserving Eggs!
I, HENRY EDWARD NEWTON, of the Office for Patents, 6, Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, do hereby declare thic
nature of this invention to be as follows;-
--
The present application has reference to a process whereby a chemical change
in the outer surface of the eggshell is produced for the purpose of rendering
said outer surface completely air-tight, and so preventing the entrance of air,
even during protracted keeping, and thereby avoiding all change in the egg
itself.
To this end; the eggs are subjected for a short time to the direct action_of
sulphuric acid, whereby the outer surface of the shell, which, as is well known,
consists of calcium carbonate, is converted into calcium sulphate. This chemi-
cally produced impervious coating of the outer surface of the shell, constitutes
a complete seal against the outer atmosphere, and permits of eggs so treated-
being kept for a long period of time, without the contents of the egg suffering
any injurious change, or acquiring any disagreeable smell or taste, and also
prevents their bursting when cooked:
In carrying out the above described process for preserving eggs by treatment
with sulphuric acid; an apparatus is employed which consists of a vessel to hold
the eggs to be treated.
To prevent the eggs moving about while under treatment, they are covered
with a perforated plate.
Tlie vessel is provided with an inlet pipe, which is connected by a flexible
tube with a movable acid-container.
There is also provided, at the lowest point of the vessel, an outlet pipe fur-
nished with a stop-cock.
Plie vessel having been filled with eggs, by raising the acid-container the acid
is caused to enter the egg-container, and when sufficient has flowed in, the
supply may be cut off by the throttling device or other means.
When the action of the acid' upon the eggs has ceased, the acid-container is
lowered, so that when tlie device is opened; the whole of the acid, which has not
been used up during the chemical' action upon the eggshells, flows back into
the container.
To remove all traces of acid from the eggs thus treated, the vessel is filled
several times with water, which is allowed to run out thiro' a waste pipe.
The eggs are then taken out, to be stowed away for keeping.
Further investigation has shewn that it is possible that foreign bodies in a
fluid form, that is to say, fowl-dung or the like, may have penetrated so deeply
into the pores of the shells, that they cannot be removed by any of the general

page_text: methods of cleansing. Such impurities cannot destroy the preserving qualities
of the sulphuric acid, but their influence upon the taste of the eggs so soiled,
cannot be prevented.
By the addition of a suitable disinfecting material to the sulphuric acid, for
example, ferric salicylate, which coagulates the above named organic impurities,
they are rendered inert.
bb
I, HENRY EDWARD NEWTON, of the Office for Patents, 6, Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, do hereby declare the
nature of this invention and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement:-
The processes hitherto proposed for preserving eggs are limited to a mechanical
covering of the eggs with a substance, by means of which it is designed to close
or stop up the pores of the egg-shells.
The substances used for this covering which have been proposed for the pur-
pose, are silicate of soda (soluble glass), lime water, milk of lime, etc., which
manifestly do not form a chemical combination with the substance of the egg-
shell.
This process of mechanically covering eggs has, moreover, the disadvantage
that eggs treated in this way, acquire a stale, alkaline taste and smell, and
their preservation, in the true sense of the word, is not attained, from the fact
that the enclosing envelope (for example, the carbonate of lime) is mechanically
applied to the shell, and, consequently,--the entrance of air through the pores
of the envlope, and the eggshell, is not wholly prevented.
Before using the lime-covered eggs, it has been proposed to use an acid,-thie
only object of which is, to break up the mechanical covering of the eggs, and
so prevent their bursting, when being boiled.
In contradistinction to this known process, the present application has refer-
ence to a process whereby a chemical change in the outer surface of the eggshell
is produced, for the purpose of rendering said outer surface completely air-tight,
and so preventing the entrance of air, even during protracted keeping, and
thereby avoiding all change in the egg itself.
To this end, the eggs are subjected for a short time to the direct action of
sulphuric acid, whereby the outer surface of the shell, which, as is well known,
consists of calcium carbonate, is converted into calcium sulphate. This chemi-
cally produced impervious coating of the outer surface of the shell, constitutes
a complete seal against the outer atmosphere, and permits of eggs so treated
being kept for a long period of time, without the contents of the egg suffering
any injurious change, or acquiring any disagreeable smell or taste, and also
prevents their bursting when cooked.
In carrying out the above described process for preserving eggs by treatment
with sulphuric acid, an apparatus is employed which is represented in the
accompanying drawing & consists of a vessel a, preferably of some acid-resisting
material. This vessel serves to hold the eggs to be treated.
To prevent the eggs moving about while under treatment, they are covered
with a perforated plate b, which is also composed of acid-resisting material.

page_text: The vessel is provided with an inlet pipe c, which is connected by a flexible
tube d with a movable acid-container e.
There is also provided, at the lowest point of the vessel an outlet pipe g,
furnished with a stop-cock.
The vessel a, having been filled with eggs, by raising the acid container e,
the acid is caused to enter the egg-container, and, when sufficient has flowed
in, the supply may be cut off by the throttling device f, or other means.
When the action of the acid upon the eggs has ceased, the acid container e
lowered, so that when the device f is opened, the whole of the acid which has
not been used up during the chemical action upon the eggshells, flows back into
the container e.
To remove all traces of acid from the eggs thus treated, the vessel a is filled
several times with water, which is allowed to run out through the waste pipe g.
The eggs are then taken out, to be stowed away for keeping.
They retain their taste unimpaired after this treatment, in spite of long and
protracted keeping, and require no further special treatment, as they do not
burst when being boiled.
Further investigation has shewn that it is possible that foreign bodies in a
fluid form, that is to say, fowl-dung or the like, may have penetrated so deeply
into the pores of the shells, that they cannot be removed by any of the general
methods of cleansing. Such impurities cannot destroy the preserving qualities
of the sulphuric acid, but their influence upon the taste of the eggs
cannot be prevented.
so soiled
By the addition of a suitable disinfecting material to the sulphuric acid, the
above-named organic impurities are rendered inert.
As a suitable disinfecting material, a solution of salicylate of iron in sul-
phuric acid is recommended.
The salicylate of iron of 10° Bé. is produced by adding to one hundred parts,
by weight, of salicylic acid, one hundred thirty-seven and a half parts by
weight of protochloride of iron, in the presence of water and air.
Of this salicylate of iron, 5%, is added to 95% of sulphuric acid of 10° Bé.,
for preserving and disinfecting purposes. The proportions may be altered, but
the above proportions have been found very suitable.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed (as communicated
to me from abroad), I declare that what I claim is:-
1. A process for preserving eggs, consisting in treating the eggshell with a
chemical agent, such as sulphuric acid, whereby the eggshell is chemically
changed for a sufficient depth into an impervious coating, impenetrable by air,
as set forth.
2. The use of a liquid for preserving eggs, and, at the same time, disinfecting
the shell of eggs, and consisting of a mixture of sulphuric acid and salicylic
acid and an iron salt, such as as protochloride of iron, as herein set forth.
3. An apparatus for treating eggs with acid for the purpose of preserving the
same, and consisting of a container a for the eggs, having a perforated plate b,
and an acid container e, to be raised and lowered, both said vessels a and e being
connected together by a flexible tube d.'
Dated this 10th day of May 1800