IMPROVEMENTS IN THE PRESERVATION OF ALIMENTARY MATTERS, AND IN APPARATUS TO BE EMPLOYED THEREFOR
Year: 1876

page_text: LETTERS PATENT to Bristow Hunt, of Serle Street, Lincoln's Inn, in the
County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS IN
THE PRESERVATION OF ALIMENTARY MATTERS, AND IN APPARATUS TO BE
EMPLOYED THEREFOR A communication from abroad by Alvaro Francisco
Carlos Reynoso, of Paris, France, Chemist.
"
Sealed the 21st November 1876, and dated the 13th September 1876.
COMPLETE SPECIFICATION filed by the said Bristow Hunt at the Office of the
Commissioners of Patents on the 13th September 1876
BRISTOW HUNT, of Serle Street, Lincoln's Inn, in the County of Middlesex,
Gentleman. " IMPROVEMENTS IN THE PRESERVATION OF ALIMENTARY MATTERS,
AND IN APPARATUS TO BE EMPLOYED THEREFOR." A communication from abroad
by Alvaro Francisco Carlos Reynoso, of Paris, France, Chemist.
This Invention relates to the application and use of the improved processes
herein-after described for the preservation of alimentary matters, and to improved
apparatus to be employed in carrying out such processes.
The improved processes comprise,-
First. The employment of cold.
Second. The employment of vacuum.
Third. The employment of compressed gases.
Fourth. The employment of sulphurous and other gases.
Fifth. The combination of special apparatus for the production of sulphurous and
other gases, and for submitting alimentary matters of all descriptions to the treat-
ment they have to undergo. These different modes of proceeding are completely
described hereafter.
First. The Employment of Cold.-The employment of cold which, as well as
desiccation, is a process, the infallibility of which is demonstrated to us by nature,
has given place successively to applications more or less favorable to preserving
alimentary matters, whether natural ice either by itself or mixed with various salts
has been employed for lowering the temperature, or machines employed for the
manufacture of ice artificially.
The Inventors have employed cold in a continuous manner to keep meat fresh
I

page_text: and bloody, albeit in a transitory manner, to effect the so-called desiccation of the
meat. We will not enter upon the examination of the first process, and the numerous
modifications of which it is capable.
Relatively to the second, the error which has been committed is attempting to
effect desiccation by currents of cold air, whilst the true method consists is realising
this desiccation in confined spaces and in an atmosphere continuously cooled below
zero, or only a few degrees above zero, but this atmosphere is not renewed. The
moisture is absorbed by means of different bodies, such as sulphuric acid, chloride
of calcium, and so forth. A condition very essential to the rapid progress of the
desiccation consists in agitating this atmosphere, or moving the absorbing body or
the matter to be desiccated, or in all the three things simultaneously.
The employment of cold may be utilized upon quite another principle, which con-
sists in cooling the alimentary matters below zero to destroy the germs which produce
putrefaction. When once these germs are destroyed the alimentary matters may
be preserved either in gas at the ordinary pressure or compressed alone, or con-
taining volatile matters, or in a vacuum, alone or with volatile matters, the cold
being employed to destroy the germs which by their development produce putre-
faction, and not for continually maintaining the temperature at zero or below zero,
the useful effects of which are obtained in a more simple manner, nor for
effecting a desiccation more or less complote, its use being altogether transitory, the
manner of employing it may be considerably varied The cold may be produced by
natural ice, by refrigerating mixtures, or by machines constructed for the manu-
facturo of ice. It is possible to leave the alimentary matters from the commence-
ment in the same atmosphere, or to cool the gases either before or after their
compression.
Lastly. By compressing gases to several atmospheres, cold for destroying these
germs will be produced by their expansion. The alimentary matters may be plunged
into either natural or artificial ice, or into refrigerating mixtures or saline solutions,
or into liquids cooled below zero in cases where powerful machines are used to
produce the cold. It will be evident that the meat should only be plunged into
such refrigerating mixtures as contain inoffensive and even preservative salts; thus,
for example, there is no inconvenience, on the contrary, there is an advantage in
plunging meat into a refrigerating mixture composed of ice and sea salt
The same
remark applies to the use of saline solutions and liquids cooled below zero.
The employment of a very intense cold as a very energetic means of destroying the
germs has answered for preparing pure preserves, only instead of employing heat as
used by Appert, the Inventor employs cold to arrive at the same result, but it must
not be forgotten that if the cold kills the germs existing at the time of its action it
leaves intact the conditions favorable to their development if at a later period
they should happen to be deposited upon the meat. It is necessary then to either
prevent the admission of new germs to the meat, or to leave the meat in such a
condition that germs freshly deposited thereon shall be destroyed by means acting
continuously. This is precisely the result attained by employing the auxiliary
means herein pointed out.
Secondly. Employment of Vacuum.-As soon as it becomes known that the pre-
sence of air is necessary for putrefaction to take place the idea occurs to the mind of
preserving alimentary matters in vacuo, or in gaseous media not containing oxygen.
Since the time of Boyle the vacuum has been considered as a radical means of attain-
ing the preservation of alimentary matters, and if it has not produced any practical
results the failure may be attributed to three causes, first, the difficulty of obtaining
the vacuum; second, that of maintaining the same in the apparatus; third,
the meat contains on its surface germs, which not only the vacuum does not destroy,
but which can develop and multiply to produce putrefaction. This will take place
to a certain degree in the most perfect vacuum. "In fact if a piece of meat is simply
placed under a receiver, and a vacuum is produced with a double-acting machine of
Bianchi's, keeping the manometer always at zero, the meat becomes putrified If,
as another experiment, a vessel containing sulphuric acid is used to effect the

page_text: dessication of the meat, notwithstanding this new advantageous condition, the meat
very frequently becomes putrified.
The Inventor has occasionally seen the irregularity of this process in placing two
pieces of beefsteak under the pneumatic receiver in prosence of sulphuric acid.
Notwithstanding the identity of these conditions one piece became dried without
putrefaction, whilst the other commenced to putrify before drying. This depends
upon the rapidity of the desiccation and the surrounding temperature. If the
temperature allows of a retardation of the putrefaction, and if the desiccation
proceeds with rapidity, then the meat becomes preserved and well dried, but in the
contrary case it becomes putrified in the vacuum. Then, in order to employ the
vacuum properly, it is necessary to commence by destroying the geims which are
upon the surface of the meat, or to cause the desiccation to proceed with rapidity,
or to hinder the putrefaction for the time necessary for its desiccation. In this case
and in all those where it is a question of desiccation in a closed chamber, it is con-
venient to agitate either the surrounding atmosphere, the body to be dried, or the
substances intended to absorb the moisture, otherwise the desiccation proceeds very
slowly.
When it is not a question of drying the alimentary matters in vacuo more or less,
but to preserve them intact in their natural state protected from the air, a
preparatory or simultaneous treatment for destroying the germs producing putre-
faction cannot be dispensed with When the process has once been commenced by
destroying the germs of putrefaction which are upon the alimentary matters, it is
not essential that the vacuum should be perfect. A very imperfect vacuum will
suffice provided that it is well maintained, and that the entrance of external air is
excluded and that the meat is surrounded by a small quantity of pure air or other
gas or vapour; thus the vacuum for instance which is obtained by the combustion of
several bodies such as alcohol, illuminating gas, and so forth in a closed chamber, or
by passing electric sparks through the same or by the employment of salts, acids,
gases, or other means of absorbing oxygen is quite sufficient. The vacuum may be
obtained by means of pumping or otherwise expelling the air, and producing
atmospheres of a different nature capable by their aptitude to effect a vacuuin.
Amongst the means comprised within this last order, superheated steam, the sub-
stitution for ordinary air of gases susceptible of being absorbed by water or other
bodies, or even of being expelled by the vacuum with more facility than air, may
be mentioned without any trace of these bodies which may remain in the apparatus
producing any results unfavourable to the preservation of the meat
When a very volatile liquid is employed already capable of being used as a
preservative agent, it is evident that by introducing into the apparatus a certain
quantity, and on creating a vacuum therein we can obtain at one operation the
destruction of the germs, the expulsion of the air, and the formation of a vacuum
more or less perfect in which there remains only a very small quantity of the
preservative matter It is then only a question of preventing the admisson of
external atmosphere. When meat is placed under the receiver of an air pump
above a vessel containing one of the volatile bodies, the preservation of the meat is
necessarily effected In this case it is best to make the vacuum very slowly and at
several times, in order not to evaporate too quickly nor to eliminate too rapidly the
volatile bodies which should remain during a certain time in the apparatus in
contact with the meat, in order to produce the destructive effect upon the germs
which produce putrefaction This substitution of a conservative vapour for ordinary
air, or of a gas having also this property (methylic ether, hydrochloric ether, or
sulphurous acid), and its subsequent elimination by creating the vacuum, gives
excellent results for maintaining meat fresh and bloody.
Instead of placing the meat under the pneumatic receiver, the Inventor often
made experiments in quite a different apparatus but in communication with a
machine for producing a vacuum. As will be seen herein-after the vacuum may if
preferred be dispensed with by causing to enter into the apparatus various gases
which maintain it at the ordinary pressure or they may be compressed. Small

page_text: .
machines have been constructed furnished with a pump worked by hand, in which
alimentary matters may be preserved in families by utilising volatile liquids and
evaporating and expelling them by the vacuum.
Relatively to the desiccation of meat in an imperfect vacuum obtained by electric
sparks, it must be noted that the small quantity of nitric compounds formed during
the passage of the sparks which happens to be condensed upon the meat of which
they strangely heighten the colour, suffice to destroy the germs, and to preserve it
from putrefaction during the time in which the desiccation takes place in presence
of the sulphuric acid employed as an absorbent of the water. The meat can also be
preserved in the same manner without desiccation under the same conditions, by
introducing into the apparatus after the action of the electric sparks, various gases
compressed to different degrees of pressure.
The employment of the vapour of water combined with the use of volatilo bodies
capable of preserving the meat, permits of a vacuum being formed with a cooler
vapour since there is already in the volatile body itself a powerful means of
destroying the germs.
It is evident that under all circumstances all the means herein described can be
employed to destroy the germs, for instance, cold volatile bodies, neutral or acid
gases, (sulphurous, methylic ether, methylic chloride), saline solutions at the ordinary
temperature, or refrigerated glycerine at the ordinary temperature or refrigerated,
either pure or containing preservative matters in solution and so forth, may be
employed.
We will now proceed to the use of steam at high pressure:-Dry steam in passing
over the whole surface of the meat kills all the germs by its great heat. This effect
having been obtained by means of a strong current, all the taps are closed, so that
the air having been driven out of the vessel, the steam in condensing forms a
perfect vacuum. The meat may thenceforward be simply kept in this vacuum, or
the vessel may be filled with the different gases herein mentioned (oxygen, azote,
hydrogen, carbonic acid, oxide of carbon, protoxide of azote, and so on), which may
be employed at different pressures according to circumstances.
Gases may be employed heated above zero in rapid and short currents, as an
energetic means for destroying the germs applicable whenever it is desirable to
attain this end. When once the germs have been destroyed by the heat of the gas,
pressure is to be applied.
Thirdly. Compressed Gases.-The idea of preserving alimentary matters in an
atmosphere not containing oxygen, or in other torms in gases, such as azote,
hydrogen, carbonic acid, oxide of carbon, and so forth at several different times, has
given rise to plans which have never been capable of practical application.
Independently of the difficulty of preventing the external air from penetrating
into the apparatus, there is in these processes as we have seen in treating of the
vacuum, a very grave error; the meat both in the vacuum, and in the different
gaseous media of air at the ordinary pressure, excepting for some gases, can only be
preserved; when the process is commenced by destroying the germs deposited
thereon, a result is obtained by the employment of means either physical or
chemical, preparatory or simultaneous. Besides which one cause of these failures
consists in the facility with which the ordinary air carrying the germs producing
the putrefaction can be introduced into gaseous media kept at the ordinary pressure.
The smallest defect in the closing of the vessel suffices for the air to enter
therein without taking into consideration that the least negligence during the
operation may cause the gases to be mixed with air during their introduction into
the apparatus. These are the facts relating to gases at the ordinary pressure, but
meat as well as all other animal or vegetable alimentary matters are preserved in
gases compressed at pressures varying from three to twenty-five atmospheres. The
Inventor has made experiments repeatedly with atmospheric air, ordinary or
purified, oxygen, hydrogen, azote, carbonic oxide of carbon, protoxide of azote,
protocarbonized hydrogen, bicarbonized hydrogen, used alone or mixed in various pro-
portio ns. In these cases, between three and twenty-five atmospheres, the above gases

page_text: or their mixtures completely destroy the germs, and prevent by the pressure
maintained the introduction of fresh germs. Besides this manner of employing
compressed gases, the Inventor has associated them with means preparatory or
simultaneous of preservation with a view to diminish the pressure, and of thus
being able to employ pressures varying only from half an atmosphere to two
atmospheres, and more frequently from one half to one atmosphere. These means
consisting in commencing by the employment of different processes capable of
destroying the germs, and then by giving the pressure with the gases desired to be
employed.
The physical or chemical means employed, preparatory or simultaneous, for
destroying the germs may act previously, and then be more or less eliminated, or
they may be associated in a permanent or continuous manner with the use of com-
pressed gases.
We will now pass these means rapidly in review :-
Firstly. The cooling or heating of the gas to be compressed, or of the matters to
be preserved, or both at one time, constitute an excellent means of destroying the
germs. The Inventor commences by cooling or heating the gases (either below zero
or above GO degrees), and then causing them to act on the meat for a longer or
shorter time, and then compressing them. The lowering or elevation of the tem-
perature will suffice, according to their intensity and their duration, for destroying
all the germs, and then permitting the meat or other animal or vegetable alimentary
matters to be preserved in any of the compressed gases at pressure not exceeding
one atmosphere (from one-fifth to one atmosphere). The destruction of the germs
by means of cold has been already treated of.
Second. The Employment of Steam at High Pressure. The dry steam in passing
over all the surface of the meat by its great heat kills all the germs. This effect having
been obtained by a very rapid current the taps are closed, so that the air having
The meat can
been expelled, the stoam in condensing forms a perfect vacuum.
then be kept simply in this vacuum, or the vessel may be filled with the different
gases herein mentioned (oxygen, azote, hydrogen, carbonic acid, oxide of carbon,
and so on), which are employed at different pressures, according to circumstances.
Thirdly The combination of the employment of these gases with the effects
obtained by the transitory or permanent co-operation of the vapours of neutral or
acid volatile liquids. Amongst these liquids may be mentioned bydruret of carbon,
methylic, and ethylic alcohol, simple and compound methylic, ethylic, and amylic
ethers, hydrochloric, biomhydric, and 1odhydric, as well as methylic and ethylic
ethers, chloroform, aldehyde, acetone, Dutch liquor, protochloride of carbon,
sulphuret of carbon, various essential oils, and so forth, acetic and formic acids, and
in general any volatile liquid capable of being employed alone as a preservative
agent. The liquids may be employed separately or combined with each other in
mixtures of various proportions. The employment of these volatile liquids, already
themselves possessed of a preservative power, may be effected in various manners.
A. The volatile liquid is placed in a vessel presenting a large surface at the
lower part of the apparatus, and also in the passage for the gas which is to be
charged with its vapours. A sufficient quantity of gas is caused to pass in to
extract all the air from the apparatus, and then a pressure is applied of from one-half
to one atmosphero As a quantity of the preservative body always remains in the
machine it is not absolutely necessary either to partially or wholly extract the air.
B The vapours of the volatile liquid must then be caused to act upon the meat
or other animal or vegetable alimentary matter to facilitate this action when once
the volatile liquid has been placed in the bottom of the apparatus in a large sur-
faced vessel a vacuum is created at several dranghts. In this manner the volatile
liquid reduced to vapour completely surrounds the meat, which is thus submitted
to a preservative bath. After having maintained this contact from one to twenty-
four hours the vapours are extracted either by vacuum or by a current of the gas
employed, and then finish by giving the pressure with this gas. There remains

page_text: then only a small quantity of the preservative vapours, which are very useful for
their permanent effects.
C. Gas containing volatile liquids is then caused to pass through, and after the
expulsion of the air a pressure of half an atmosphere is given to them, which is
maintained during several hours, after which gases are made without any vapour,
in order to drive out by a washing process that which 18 in the apparatus, and
finish by giving pressure of from one-half to one atmosphere.
D. The volatile body is made to act simultaneously or in a permaneut manner by
placing it in the lower part of the apparatus, and also by charging with its vapours
the gases employed, and with which the pressure is given. This manner of
operating can be varied by placing the volatile liquid at the bottom of the
apparatus, and then creating a vacuum to evaporate the liquid, and afterwards
introducing the gas with which the final pressure is given.
E The previous experiment may also be made in the following manner :-The
volatile body is placed in the lower part of the apparatus. A vacuum is then
made for volatilizing it; the pure vapours are then allowed to act during a specified
time, and afterwards the ordinary or purified air is introduced very slowly, and
with it a pressure is given of from one-half to one atmosphere Amongst the bodies
above indicated methylic ether (boiling at 21 degrees) and chloride of methyl (boiling
at 22 degrees) are gases, and as such they can be introduced into the apparatus in
which the meat is placed, and can be maintained in contact with it during a certain
period either at the ordinary or at an increased pressure. Meat may be served in a
similar medium, or after a contact more or less prolonged the gaseous others are
driven out either by a vacuum or by currents of other gases, and the final pressure
is given with the latter, so that the ethereal gases act preparatorily to kill the
germs, and then in a permanent manner for the small quantity which may be left
in the apparatus if thought proper.
Fourthly. The previous or permanent employment of sulphurous or hydrosulphuric
acid Relative to the use of sulphurous acid the details will be found herein-after.
Concerning hydrosulphuric acid when a current thereof is caused to pass into the
vessel containing the meat, and left to remain some time in contact therewith at the
ordinary or at a lower pressure, it destroys the germs, and the hydrosulphuric acid
may be eliminated by a vacuum, by a gaseous current, or by the employment of
sulphurous acid. The sulphurous acid being eliminated the pressure is given with
the desired gas.
Fifthly. The immersion of meat in solutions of salts or preservative acid, or in
glycerine containing salts in solution, or mixed with the above-named volatile
Liquids, or the solutions of the said volatile liquids, or of gases (mothylic ether,
chloride of methyl, protoxide of azote, sulphurous acid, hydrosulpuric acid, and so
forth) in water or in alcohol. Some of the processes which arise from the com-
bination of the means above described will now briefly be indicated.
The alimentary matters are first submitted to the action of a bath in solution of
various preservative salts; they are then placed in the apparatus, in order to cause
the gas to be passed over them to expel the air more or less and give the final
pressure, the saline solutions being at the ordinary temperature either slightly
warm or cooled below zero, the cooling effect will be obtained either from refri-
gerating mixtures or by machines employed for making ice. The meat may itself
be placed in the refrigerating mixtures when these mixtures contain the salts which
it is desired to employ, such, as, for instance, chloride of sodium or ice, or the meat
may be placed in glycerine either pure or containing salts in solution cooled below
zero, or slightly warm. After the meat has been submitted to these preparatory
treatments it is placed in the apparatus, and the gases caused to pass through to
eliminate the air more or less, and the final pressure is then given. These processes
can be combined and varied to an endless extent with the use of the vapours of the
above-named preservative liquids.
It is also possible to steep the meat in solutions of phenic acid, salycic acid,
acetic acid, formic acid, sulphurous acid, and so forth, and to withdraw it after being

page_text: left a certain time in contact with these bodies, and it is then placed in the
apparatus, the current, of gas is admitted, the air is driven out, and the final
pressure is given By this means the inconvenience of a permanent immersion in
aqueous solutions is avoided.
Fourthly The Employment of Sulphurous Acid.-The antiseptic properties of this
acid have been established for some time by various experimentalists, and they have
employed it either in a free state in combinations with neutral or acid salts or as a
solution in water. Notwithstanding the excellent effects which have been obtained
by its application its use has not been extended.
Amongst the reasons which will explain the abandonment of this process may be
enumerated, firstly, the uncertainty of the results, both of the preservation or relative
to the alteration of the colour or flavour of the alimentary matters; secondly, the
defective means of producing the sulphurous acid It is requisite to be able to
obtain this acid constantly, and in a rapid and regular manner, so as to be enabled
always to know the product employed, and to introduce at a fixed point the doses
necessary for merely obtaining the desired results without complications of any
kind. Otherwise the process is conducted at haphazard; sometimes good results
are attained, and sometimes bad. One is never master of the power, so as by
knowing the conditions to determine in each case the results which will be
produced.
The Inventor prepares pure sulphurous acid, either in the state of gas, or in a liquid
state, or in a solution in water. Most frequently the sulphurous acid in the gaseous
state is mixed with oxygen or azote in various proportions, when it is created by
the combustion of sulphur in presence of a current of air
The quality of the sulphurous acid depends upon the size of the apparatus, the
regularity of the operation, the surface of the sulphur which enters into combustion,
or of the quantity of air injected per minute. In the experiments made the
strenghth of the sulphurous acid contained in the gaseous mixtures varied from 5 to
11 per cent. The preparation of sulphurous acid by the combustion of sulphur in
a current of air takes place in a closed vessel, in which the combustion of the
sulphur is confirmed by a current of air injected by a pump.
The apparatus should be arranged in such a manner that the operator can, firstly,
supervise the combustion of the sulphur; secondly, weigh the amount of sulphur
burned during the operation, and control this weighing by another more exact, after
the termination of the experiment; thirdly, readily take samples of the gaseous
mixtures, in order to determine by analysis the quantity of sulphurous acid which
it contains. When the capacity of the air pump and the number of strokes of the
piston per minute are known, and on the other hand the quantity of sulphur
burned, we have approximately the quantity of the gaseous mixture, the composition
of which is only constant after a few minutes of combustion, and thence its com-
plete regularity is established The capacity of the pump is established once for all
by means of a gas meter, and the number of strokes per minute of the piston is
ascertained by a counting machine in a very exact manner, although it is sufficient
to count the number of strokes for one stroke of the steam engine.
The following is the arrangement of apparatus for producing sulphurous acid,
such as has been employed in the experiments as to this Invention
In Sheet 1 of the annexed Drawings Figure 1 represents a vertical section of the
sulphur furnace This furnace consists of a circular or other shaped vessel A in
cast iron, in the interior of which the sulphur is placed in a sheet-iron box a, in
which the body is burned. The bottom of this box does not touch the vessel, but
it is supported on four small fect a². Four rigid iron rods a² uniting at A³ serve to
support it. From the point A¹ there is also a thin annealed iron wire x which
passes through the lid at B and passes round the groove of a pulley p carried by
two points p¹ and p² (Figure 2) Its other extremity passes through a hole made.
in a small cylinder M, and is fixed therein by the aid of a screw V. The other
screw V' holds the rod t supporting the plate T which carries the weights. Figure 2
not only shows how the support S is screwed to the cover of the apparatus but also

page_text: how it forks into two branches at its upper part; one part c. carrying a small axle,
against which the point p³ of the axis of the pulley 2 presses, the other is pierced
with a screwed hole, in which the tightening screw V passes and carries the other
point p² of the axis..
Two spy holes g and g¹ placed above the level of the burner a allows what is
taking place in the interior of the apparatus to be seen and attentively followed;
they are formed by two pieces of glass screwed opposite each other into the
walls of the vessel, so as to leave a small circular rim at the bottom not screwed,
against which the glass g¹ is held by the piece or nut T screwed into the wall.
These spy holes also serve for feeding the apparatus with sulphur during the
operation; all that is required is to unscrew the nuts T which carry with them the
glasses g, gl, into the hole; the half cylindor, seen at Figure 3, is introduced and
carries the sulphur in its concave part. When the half-cylinder is in the interior it
must be turned half over, and the sulphur falls into the sheet-iron box a. R is the
tap by which the air injected by the air pump (and passing through a tube formed
of concentric layers of sheet iron and vulcanized india-rubber) is introduced into
the apparatus. A ligature formed of annealed in on wire united the end of the
extremity or tube to the screwed part e, d, of the tap R, the other screwed part e¹, d',
serves to fix the tap R on to the wall of the vessel A
The copper tube G is
attached by a conical joint 7, 8, to the tap R; the ing T tightens this joint; the
tube G-being bent at a right angle terminates in a rose P pierced with fine holes;
it is in passing through these fine holes that the air is projected against the sulphur,
previously lighted.
The burnt air containing the sulphurous acid produced passes out by the tap R¹
and flows through a tube to its destination This tube differs from that which
supplies the air, inasmuch as its interior contains a worm formed of thick iron wire,
which, at the same time, that it sustains it prevents it from becoming flattened,
whatever may be the position which it occupies. X is a third tube belonging to the
tap R¹ which serves as a proofing tap, hy nieans of which samples of the gas may
be taken in the operation of the apparatus in order to make an analysis thereof
and-to determine the quantity of sulphurous acid it contains The cover in which
the tap is screwed is fixed by six bolts to the flange of the vessel; certain corres-
ponding marks on the cover and on the flange show the position which it ought to
occupy. The washer of vulcanized india-rubber serves to keep the joint tight on
the screwing-up of the bolts. Lastly, on the cover is a safety valve Y, which is
useful when working under pressure.
It is useless to describe the action of the apparatus, at the same time it would
bo too long to give all the variations of which the apparatus is susceptible.
It has sufficed to describe the general principles which ought to govern its con-
struction, so as to be able to effect the combustion of the closed chamber, and to be
able to weight the amount of sulphur burnt during the whole operation; also to be
able to survey this operation, and as a general precaution to be able to take samples
of the gas for analysis.
It is evident that several different arrangements of this apparatus may be made.
For instanco, instead of weighting the sulphur directly any weighing machine or
steelyard may be employed. In order to regulate the admission an air reservoir
may be employed after the pump, and so on. When it is a question of producing
sulphurous acid at a pressure exceeding that of the atmosphere, or to inject it into
the apparatus at a pressure exceeding the atinospheric pressure, the general and
permanent arrangements of the apparatus are invariable, but then it is completely
closed, and no artificial means are omployed to weigh this sulphur externally during
the course of the operation. In this case the apparatus should be completely closed;
however, even in this case, one can with great certainty ascertain the combustion of the
sulphur while the process is going on by the analysis of the air, and the measurement
of the quantity of air injected. The preparation of the sulphurous jacid by
means of a sulphite or bisulphite of potash, soda, or lime, and of an acid such as
sulphuric, hydrochloric, and so forth, is effected in apparatus similar to that em-

page_text: ployed for producing (commercially) carbonic acid, by decomposing the carbonate or
lime by sulphuric acid
To wash these gases the Inventor employs a very concentrated solution of
bisulphite. The production of bisulphite of potash, soda, or -lime, may be effected
either at the ordinary pressure, or at a higher pressure in an apparatus resembling
the saturators employed in the manufacture of gaseous carbonic drinks.
The facility with which sulphurous acid can be made by different methods
enables us also to obtain very easily the same sulphurous acid in a liquid stato,
either by cooling the same below zero in refrigerating mixtures or in machines used
for manufacturing ice, and enveloping the tubes or reservons which conduct the
sulphurous acid, saline liquids, or saturated solutions so as to reduce their tempera-
ture considerably below zero, either by compressing the sulphurous acid or by com-
pressing and refrigerating it at the same time.
Very concentrated solutions of sulphurous acid in water, alcohol, or aldehyde,
obtained with a strong pressure and retained in very strong reservoirs, may be very
useful, whether employed directly in their state of solution or whether the sul-
phurous acid is caused to evaporate completely by heating them in vacuo, or by
causing them to pass through a gaseous current, either of which methods may be
employed, according to cucumstances.
The employment of sulphurous acid will now be treated of, and concerning which
it is set forth as an incontestible fact that if the sulphurous acid is a very energetic
means of preserving alimentary matters, on account of its antiseptic properties, it
presents, nevertheless, grave inconveniences on account of the tasto which it gives
to the matters which may be so prominent (according to the quantity of sulphuric
acid) that they become altogether unsuited for human food. This matter must only
be employed with the precautions which we will here enumerate.
Theoretically speaking it is evident that sulphurous acid, as well as all other
chemical or physical means capable of killing the germs productive of putrefaction
may be altogether eliminated after having fulfilled this destructive function. This
complete elimination of the sulphurous acid may be effected by a vacuum, by
washing, by means of a long current of any gas, continued or maintained until
the issuing gas when tested by iodide of starch gives no trace of sulphurous acid;
or, finally, by means of hydrosulphuric acid, which, in acting on the sulphurous
acid decomposes it, and at the same time becomes itself decomposed, so that thereby
water and sulphur are produced. The quantity to be employed depends upon the
proportion of sulphurous acid desired to be removed, so that it is possible to
eliminate all the sulphurous acid or only a portion thereof. As the sulphurous acid
and sulphuretted hydrogen in a moist state have the property of decomposing
each other, and since both of them possess the property of destroying the germs, it
will be understood that each of them inny be used alternatively to produce the de-
struction of the gerins, and afterwards employing the other to eliminate the one
required to be expelled. Sulphuretted hydrogen may be employed to eliminate sul-
phurous acid, and the latter to eliminate the former.
Whatever may be the means employed to eliminate the sulphurous acid it is
evident that a complete expulsion of this acid, after having by its contact with the
alimentary matter destroyed all the germs, would leave them in the condition of perfect
preservation and indefinite so long as fresh germs are not allowed to be deposited
thereon. In fact the employment of compressed gases by preventing the admission
of atmospheric air into the apparatus fulfils this latter very essential condition.
Even under very low pressures the gases, according to their solubility in water and
their diffusability, exercise already, under these conditions, a more or less extended
preservative power. But if it is easy to unite in a laboratory all the conditions
most favourable to the accomplishment of certain phenomena, in practise on a large
scale, complications may be feared, and only such processes as are altogether free from
5 chance of accident must be placed in the hands of workmen to obtain the desired
result-Firstly. The destruction of all germs existing at the commencement of the
experiment on the meat must be absolutely cortain, because one alone which might.

page_text: escape death would suffice to occasion the entire putrefaction of the meat. Again,
there must be a guarantee against the effects of the admission of new gerins during
the course of the experiments when the conditions favorable to their destruction
no longer. exist. To avoid the inconveniences which might follow under each of tho
events it is advisable always to leave permanently a certain quantity of sulphurous
acid on the meat. This small quantity being sufficient to obtain the desired effects
do not alter in any degree the catable properties of the meat, and at the ond of a
certain time it disappears by virtue of the proved reactions arising from contact with
the meat. With regard to this quantity of sulphurous acid, it is evident that it
depends upon circumstances. If an excess of sulphurous acid is employed at the
commencement, which is afterwards eliminated, it will be very small; but if the
sulphurous acid is employed at once in a permanent manner, without subsequent
elimination, it will necessarily be larger. It remains to be determined what is the
weight of this minimum quantity of sulphurous acid relative to that of the meat,
and above all it is necessary to inquire whether from the result of experiment it
is sufficient to destroy the germs in the long run. The investigation of this quantity,
fulfilling these two conditions, is very difficult. However, by voiy numerous ex-
periments, the Inventor has found that it varies from 0.2 to 0.5 per cent. of the
weight of the meat.
-The
Experiments of this nature should be made in the following manner :-
meat being placed in the apparatus the air is first to be expelled by means of a
current of the gas desired to be employed, and when the gas, on analysis, is no
longer charged with air, a small pressure is given (from 15 to 20 centimetres of
mercury). Afterwards the sulphurous acid gas is introduced until the manometer
indicates by its pressure the desired quantity When once the sulphurous acid has
been introduced into the apparatus the final pressure of from one-half to one
atmosphere may be given by introducing the first gas again. The sulphurous acid
for this experiment is prepared in an apparatus used in industry to obtain carbonic
ncid Sulphurous acid is prepared by the decomposition of a bisulphite by
sulphuric acid. The only change which the apparatus undergoes is a leader tube
which conducts the sulphurous gas from the generator to a small washer above, in
which is placed a very strong solution of bisulphite.
The employment of liquid sulphurous acid allows of an exact dose by weight,
the same as a solution of sulphurous acid. From the moment the dose of sulphurous
acid which unites the double property of preserving the meat and not altering
its flavour is determined on it is evident that the question is much simplified. In
fact the experiment is made also in another manner.
In the first place a slight pressure is given (of 15 to 20 of mercury) by means of
ordinary air. Then the sulphurous acid is introduced, and afterwards the air is
injected again to the pressure of one-half or one atmosphere. As the sulphurous
acid destroys all the germs existing on the meat and in the air, at the same time
the meat holding in reserve also the preservative agent, is surrounded by an
atmosphere of pure air, incapable of effecting its putrefaction. The same result is
now arrived at which was had in view in the previous experiments by other means.
In commencing there is determined almost empirically, and without fixing it in an
absoluto manner, what is approximately the quantity of sulphurous acid which
may remain on the meat without its flavour being altered, and under what fixed
conditions one must be placed in order that this quantity shall always and with
certainty remain on the meat.
Operating always under the same conditions one is sure to obtain in all cases
the same results, even though the exact dose of one of the circumstances fulfilled is
ignored. This point being determined and noted any excess of sulphurous acid
may be employed which may be thought proper, provided that a sufficient quantity
is afterwards driven out so as only to leave the dose desired, which at the same
time that it is a preservative does not alter the comestible properties of the meat.
The numerous circumstances under which the Inventor has employed sulphurous
acid from its state of absolute purity to its dilution in an excess of air or other

page_text: gases are not all useful to be known, because they do not lead to practical
applications, and very frequently the only useful instruction to be derived there-
from has been the inconveniences which they present, which are very important to
be known in order to avoid them in the actual processes Several trials will
therefore be passed over, and only those which are either capable of being applied
on a larger scale or which will throw considerable light upon the question will be
referred to. To avoid repetitions it will be useful to know that the Inventor's
experimental apparatus consisted of cylinders of a capacity of 850 litres, and that
he always operated upon quarters of beef from 30 to 65 kilogrammes, and on sheep.
weighing from 10 to 27 kilogrammes He also employed pork, veal, venison, fish,
fowl, partridges, and so forth. The pump which he employed delivers 2 litros of
air per stroke, and with his steam engine it gives 100 strokes of the piston per
minute. Thus he injected into the sulphurous acid apparatus 200 litres of air
per minute.
The apparatus being charged with a small sheop of 10 kilos.
weight divided into two, it is necessary to pass in 1800 litres of carbonic acid in
order that the air should be completely expelled, and to have an atmosphere of
pure carbonic acid. The quantity of carbonic acid necessary to displace a body of
air depends upon the velocity of the current and upon the skill of the operator to
conduct the work. He burnt from 100 grammes of sulphur (in six minutes) to
1520 grammes in 55 minutes. It is useless to enter into the details of a great
number of experiments in which he burnt other intermediate quantities (200, 250,
400, 500, 700, 800, 900, 990, 1200) which have been employed at several times.
The combustion of sulphur by weight per minute is not always constant; it may
be considerable or small. The gaseous mixture contains from 5 to 11 per cent. of.
sulphurous acid, that is to say, a mean of 8 per cent. of the acid. Instead of
burning the sulphur for producing the gaseous mixture containing azote, oxygen,
and sulphurous acid, and from 5 to 11 per cent. of sulphurous acid, the Inventor is
convinced by several experiments that the same results might be arrived at by.
injecting into the apparatus a quantity of pure sulphurous acid so as to establish a
medium containing from to 11 per cent of sulphurous acid. In the case wherein
the sulphur was burned in his sulphurous acid apparatus naturally the gas was
allowed to escape by a tap until the quantity of sulphur desired to be burned had
disappeared. This is a real washing of the meat and a complete renewal of the
atmospheric medium in which it existed from the commencement of the experiment..
Then the taps are to be closed and the meat left in contact with this atmosphere.
charged with from 5 to 11 per cent. of sulphurous acid from about half-an-hour to
three hours. During this contact the germs are attacked and the meat absorbs the.
sulphurous acid With regard to the duration of this contact it may be remarked
that the more energetic and intense the means for destroying the germs may be
the less time is necessary for attaining this result, and on the contrary the less
energetic it is, either by itself or by the diminution of its intensity, the inore pro-
longed must be the time of its action. Thus, for example, everybody knows that the-
maturing of wine, which takes place rapidly at 100 degrees, does not do so at 60
degrees, excepting when this temperature acts for a sufficiently long time. If pure
sulphurous acid is employed the action will be very rapid, but when the sulphurous
acid is diluted with other gases it takes longer to, obtain the effect. On the other
hand it must not be forgotten that a certain time is necessary for assisting the
absorption of the sulphurous acid by the meat. The employment of pure.
sulphurous acid would be very costly, and the Inventor prefers, in order to
augment the action of the acid when diluted with other gases to prolong the
contact and to assist the accomplishment of the end desired by a slight increase of
pressure. In general he maintains the contact an hour and a half, which time is.
equally applicable to all cases which he has studied by varying the doses of
sulphurous acid. When this time has elapsed the gas desired to be employed
(purified air, oxygen, azote, hydrogon, carbonic acid, oxide of carbon, protoxide of
azote, and so forth) is caused to pass in either alone or differently combined, in
quantities varying from 1800 to 3600 litics to carry away the gas in excess and to

page_text: give the final pressure. To adopt this number of 1800 to 3000 litres the Inventor
made several. experiments on pieces of beof weighing 32 kilogrammes, in which
1200 grammes of sulphur were burnt in 55 minutes. The excess of the gaseous
mixture containing sulphurous acid was allowed to escape, and the meat was
afterwards kept in the closed apparatus in contact with the gaseous mixture
contained therein for one hour and a half. Then 5000 litres of carbonic acid were
admitted which still contained in its latter portions some sulphurous acid, as was
ascertained by several trials by means of iodide of starch. Thus then the carbonic
acid does not confine its action to simply renewing the medium in which the ment
is placed, for then at the inost 1800 metres would have amply sufficed to drive out
all the gas at the previous atmosphero and replace it by pure carbonic acid, but
moreover, having produced this effect, it carries away also the sulphurous acid-
condensed in the meat.
With regard to this gascous washing it should be observed that the choice of the
gas is not unimportant, and also the velocity of the current exercises a certain
influence. It is by hydrogen that the sulphurous acid is driven out most rapidly.
However this may be, it is not well to carry this effect too far, so that thero always
remains a certain quantity of sulphurous acid on the meat This is precisely what
is obtained by employing from 1,800 to 3,000 litres of carbonic acid or other gas,
not only to wash but also to give the pressure.
It is evident that all these numbers relate to the Inventor's apparatus; hereafter
they must be varied proportionally according to the new apparatus.
The final pressure has been from one-half to one-and-a-half atmospheres. In
general the pressure has been from one-half to one atinosphere. The work to be
performed by this pressure in these cases is well determined for most gases. The
germs having been destroyed, perhaps totally, during the passage of the gascous
mixture containing the sulphurous acid, and afterwards during the contact in a
closed vessel containing the said mixture, and to a certainty if they have not been
all destroyed by these two processes they are so afterwards by the small quantity
of sulphurous acid which remains on the meat. The role of the greater part of the
compressed gases, excepting those which are either very soluble or very diffusible, is
hero limited simply to preventing the introduction of the external atmosphere
without having recourse to soldering, and for this purpose the manometer of the
apparatus should be continually examined for re-establishing the pressure by means
of the introduction of more gas in cases when too great a loss takes place. The loss
can be allowed to go on without inconvenience until there are only 20 centimetres
of pressure left at the opening of the apparatus.
The washing of the meat by the gaseous current containing sulphurous acid is
very useful, because the agitation of the current assists the sulphurous acid in being
brought into contact with every part of the meat, and for this purpose the direction
of the current should be changed sometimes from bottom to top, and sometimes
from top to bottom.
The mixture containing sulphurous acid may be left in the apparatus in order to
replace the atmospheric medium in which the meat was immersed at the ordinary
pressure. However, the Inventor prefers as a precaution (and also to increase and
regulate the actions of the sulphurous acid) to give a slight pressure, which may be
only from 1 to 1/, of an atmosphere, and which is maintained during one hour and
a half. In this manner the sulphurous acid is sure to penetrate everywhere, and to
be brought into connection with all parts of the meat. Thus in an experiment
which may serve as an example, 31 kilos., 500 of beef were submitted during onc
hour and a half to the passage of the products of combustion of 1,600 grammes of
sulphur; then this mixture, containing an average of 6 per cont. of sulphurous acid,
is kept in contact with the meat at a pressure of one-fifth of an atmosphore during one
hour and a half. At the end of this time the pressure was 13 instead of 15, which it
was at the commencement; afterwards, in order to renew the atmosphere of the appa-
ratus to withdraw the excess of the sulphurous acid remaining on the meat, and to give
the final pressure of oue-half atmosphere, 3,600 litres of carbonic acid was employed.

page_text: During the course of this description there is presented in a very general manner
the results of more than 100 experiments on a large scale, and of thousands of others
which have been made in the laboratory. The experimental data thus obtained
naturally will serve to deduce those which should be applied under different circumi-
stances, and the general principles having been established they may be modified
according to circumstances under which the operation was performed, and according
to the object to be attained.
Owing to the precision which the Inventor has introduced in the employment of
the sulphurous acid, in arranging the means required to prepare it with great facility,
and to the exact dose of this body in each case, its use presents no further incon-
venience, and one can fix from all points of view the limits and conditions of its
employment, for all the data in order to effect the same with certainty are known,
and can be fulfilled.
The Inventor's experiments have lasted sometimes during six months and some
days, and for all this time the meat has been kept fresh and juicy. The pieces pre-
served during this time weighed 42 and 46 kilos.
The means herein described, as also all the processes mentioned, are applicable
according to different cases, and with the modifications suitable for the preservation
of all alimentary matters, whether vegetable or animal. They have been applied to
the preservation of fruits, vegetables, milk, butter, and so forth, as well as to that of
meat (beef, mutton, pork, and others), fowls, fish, game, eggs, and so forth. The
preservation of fruits, vegetables, and so on in gascous media other than air and
oxygen may be effected for these other gases (azote, hydrogen, carbonic acid, oxido
of carbon, protoxide of azote, and others) alone or mixed, whether at the ordinary
pressure or at very slight piessures not exceeding one atmosphere.
In these experiments the pressure employed has often varied from 1/10 atmosphero
to one atmosphere.
The employment of gases may be associated with that of vapours volatile
liquids, as herein-before more fully pointed out with regard to meat. All that has
been said with relation to meat applies to the preservation of fruit, vegetables, and
so forth
Production of Certain Gases.-The production of the gases by the ordinary means,
and which are found published in all chemical treatises, are not mentioned herein.
Pure carbonic acid is prepared in an apparatus which is also used for the preparation
of hydrogen and sulphurous acid. At the commencement of these experiments
impure carbonic acid was prepared by burning wood ashes in a current of air, and
for this purpose the same apparatus was employed which served for the preparation
of the sulphurous acid by the combustion of sulphur, the wood ashes being placed in
the bottom of the apparatus, and after having burnt it the air was injected. This
most simple proceeding presents this inconvenience, the empyreumatic odour of the
gases, which also might be purified by a washing through sulphuric acid, or per-
inanganate of potash, soda, and so on
In order to purify the air by means of heat, as well as for preparing the oxide of
carbon, the apparatus represented in Figure + has been employed; this is a drawn
ion tube T of 0 150 in diameter, and of 0m 950 in length. It is provided with
two flanges, which are fixed thereto by bolts, and in each one of these flanges is
screwed a small iron tube t of 0m 040 diameter. At the centre is placed an iron
rod u, on which are threaded a series of perforated plates v
The joint of the flange where the air or the carbonic acid enters may be made in
red lead, but the other must not be made of this substance, the heat being so great
that it melts like lead A thick cloth known as " asbestos felt" is preferable.
In order to purify the air the apparatus is first heated to a red heat, and after-
wards a very slow current of air is passed through. To prepare the oxide of carbon
wood ashes are placed between each plate so as to be in very uniform layers. A
great heat is applied, and when the wood ash becomes a white heat carbonic acid is
injected thereinto, and becomes transformed into oxide of carbon. If it is wished

page_text: to have the oxide of carbon quite pure it would be necessary to wash it with potash
to absorb the excess of carbonic acid. However, the carbonic acid furnace may be
also employed for making oxide of carbon by charging it in a special manner. It
is sufficient to put in carbon only, and to inject a small quantity of air, the carbonic
acid which is found in the bottom of the apparatus being compelled to pass through
the layer of heated carbon is transformed into oxide of carbon.
The furnace for manufacturing carbonic acid, which is represented in vertical
*section at Figure 5, presents this peculiarity that it acts by a forced current, that is,
the air which supports the combustion is introduced under pressure by the tap R.
It is therefore necessary that it should be air-tight, but in addition to this the
joints must be movable, because the mixture of charcoal and carbonate of lime
must be introduced, which serves for the manufacture of the carbonic acid.
As the air introduced at the lower extremity the bottom F remains cold, and
single ring of india-rubber f is sufficient, but the lid C becoming very much heated
it is impossible to use this material, nor even sheet lead, but the object is effected
by placing lampblack in the circular groove, and pressing it in tightly. On applying
the lid afterwards, and tightening the screw V, the joint is perfect. Instead of
lampblack powdered lime or very fine sand may be used.
In order to put the apparatus to work its bottom F and its cover Û are romoved,
a sheet iron grating introduced through the top falls and rests on the conical part of
the bottom. Incandescent charcoal is then poured in, then unlighted charcoal, which
becomes lighted by degrees as the current of air from bottom to top is strong
enough. Finally, limestone is thrown in, and when this is heated a new layer of
charcoal and limestone mixed in the proportion of two volumes of the former to one
of the latter. When the proper time to commence collecting the gases has arrived
the launpblack joint of the covering is made good, the bottom joint is tightened,
and the air pump is put in action. This air passes out by an india-rubber tube,
and enters the furnace by the tap at the bottom. It comes out partly transformed
into carbonic acid by the tube shown at the top of the apparatus. Another copper
tube covered with rags soaked in water, which cools it, leads to a closed apparatus
containing wood embers in small pieces, in order to purify the gases from the solid
particles which may be in suspension therein, and from certain tarry vapors, and so
forth. It comes out by a tube at the bottom of the apparatus, thence passing out
at the top of a worm pipe surrounded by water, and becomes cooled thereby. It is
then conducted by an india-rubber tube to any desired place.
Instead of making a special apparatus to effect the filtration, so to speak, of the
gas, the apparatus in which the sulphurous acid is prepared may be used, which
perfectly answers the purpose.
Apparatus in which the Meat is Placed.-Figure 6. This is a cylinder C termi-
nated by two convex covers; the interior diametor is 0m 80, and the height of the
cylindrical part 1m 65. The bottom is the same as the top, excepting that it has one
tap only in the centre. The passage of the large taps is om 035, and that of the
small one is 0 012. The cylinder is of sheet iron; the angle iron c is rivetted on
to it, and a ring c¹, also made of iron, is fixed on to the cover, and between them is
placed the ring of vulcanized india-rubber r. The tightening is effected by means
of bolts 0 016 in diameter, the centres of which are 0m 011 from each other. A
round iron bar B, 0020 in diameter, the extremities of which are bent at right
angles, and enter small sockets b rivetted to the angle iron c supports the meat to
be submitted to the experiment suspended by a hook. The taps R and R' situated
at top and bottom of the apparatus serve for the admission and exit of the gas.
The taps receives a manometer, which indicates the pressure. Besides the cylin-
drical apparatus others have been employed of a square meter in capacity. These
are useful, especially for the preservation of fruits and vegetables, their opening
and size allowing of the introduction into the interior of the proper means for
sustaining and easily arranging the same. In the last-mentioned apparatus thero
is one whole side which can be removed to form the man-hole by which the sus-

page_text: pending apparatus is introduced. The cover is fixed by bolts similar to those of
the preceding apparatus, and so that the joints should be air-tight an india-rubber
ring is placed between them.
In
Production of Pure Sulphurous Acid. The apparatus herein-before. described
(Sheet 1) is that employed to obtain sulphurous acid by the direct combustion of
sulphur by means of air It is evident that even under the best conditions only a
mixture of azote, oxygen, and sulphurous acid can be obtained by this process, in
which the sulphurous acid can reach an extreme maximum of 20 per cent.
several experiments this mixture can be employed very usefully, besides it may be
rendered richer in sulphurous acid if the combustion of the sulphur were carried
on in oxygen instead of in air; but in other cases where the doses of sulphurous
acid should be very exact it must be employed pure.
We obtain pure sulphurous acid by the reaction of an acid (sulphuric, hydro-
chloric, tartaric, or others) on a bisulphite potash, soda, lime, and so forth). The
sulphurous acid gas which is given off during this reaction is washed in bisulphite,
and is afterwards dried by chloride of calcium or pumice stone impregnated with
sulphuric acid, so as to be employed in a gaseous or liquid state in a refrigerating
mixture. The apparatus to obtain it reduced to its simplest form would consist
principally of a copper vessel lined with lead, in which the bisulphite would be placed.'
It would be surmounted by a second copper vessel lined with lead containing the
acid; the internal level of this acid would be marked on the outside by a glass
tube. The acid would flow out by an opening which might be increased or
diminished by means of suitable mechanism, in order to be able to let more or less
acid flow out. The acid falling regularly on the bisulphite produces sulphurous
acid gas
In the generating vessel (the lower one) a mechanism would be provided for the
purpose of stiîing up the mixture of the acid and the bisulphite. The gas produced
passes into a vessel containing bisulphite, where it is washed and so forth, and then
into another vessel containing the matters intended for drying it. If it is to be
liquefied it must then be caused to pass by a worm surrounded by a refrigerating
medium capable of lowering the temperature at least 20 degrees below zeio. It is
possible to take away this dried gas by means of a pump to compress it, as will be
seen herein-after. It is evident that the form and arrangement of the general
apparatus just described may be varied ad infinitum. In practise the most simple
and the most easy to maintain in a state of cleanliness is the best.
.
Two special arrangements of this apparatus will now be described.
This
Figure 1, Sheet 2, is a section of an apparatus to preparo, wash, dry, and liquefy
the sulphuric acid gas, Figure 2 is a horizontal section of the same.
apparatus may also be applied for the preparation of carbonic acid, hydrogen, and
so on. The gas generator P is a cylindrical vessel with a conical bottom terminating
in a large leaden tap D. The apparatus is made of copper to give it strength, but
it is lined with lead to render it indestructible by acid. Its cylindrical portion is
fixed to the top and bottom by bolts which hold two flat rings c of india-rubber;
this very solid and air-tight joint is rendered still more so by rims on the flanges,
which prevent the displacement of the joint by internal pressure; thus the
generator may be dismounted with facility and rapidity, either to clean or repair it.
The reservoirs R and R' are also made of copper lined with lead or of lead alone;
one of them contains sulphuric acid and the other the solution of bisulpite of soda,
the mixture of which produces the sulphurous acid gas, they have no fixed cover, so
that their upper surface receives the atmospheric pressure directly. The tubes T
are fixed to the cover of the generator, and at their top the two reservoirs aro
screwed; they also receive two conical plugs b, b¹, either in lead or copper covered
with lead, and made of one piece with or fixed firmly to the axis d, d, which passes
through them. Screwed washers e and e¹ are employed to prevent any lateral
movement, and also for screwing up the plugs; the latter are provided with two
cavities and f1, the sizes of which are in proportion to the volumes of the liquids
to be mixed; that is to say, as 1000: 138 or approximately as 100:15. If then by

page_text: the aid of a strap passing round the fast pulley p the axis d is caused-to revolve
uniformly, the plugs in turning round will empty the liquids with which they were
filled into the tubes 9 and 7', then the latter into a small leaden cap C fixed to the
cover by the rod t; the liquors are thus compelled to react there one on the other,
in the proportions indicated by their equivalents. Their reciprocal action is com-
plete, or nearly so, and if some particles escapo falling mixed to the bottom of the
generator they will finish by reacting completely one on the other. The continual
movement of the liquid allows of dispensing with an agitator, so irksome in
apparatus of this nature; in proportion as the liquids disappear from the vessels R
and R¹ they can be renewed without difficulty, as their covers are not fixed.
According as the speed of rotation of the axis d is great or small more or less
gas will be produced in a given time, but the same production of gas will always
correspond to the same speed. The gas is produced without jerks and in an uniform
manner. If the receivers R and R₁ are graduated the volume of liquid employed,
and consequently the quantity of gas produced, may be known at any moment. To
stop the apparatus the movement of the shaft & must be arrested by passing the
strap on to the loose pulley p¹.
When it is judged expedient, and during the process, the generator may be
emptied of the residuum of its reaction by means of the tap D.
This apparatus presents one defect, which is that when the movement of the
plug is not produced by power but by the hand of the operator turning a crank.
fixed on the axis d, as the operator may at will accelerate or diminish the speed the
production of the gas will not be uniform and the pressure will vary proportionally
to the variations of speed; in a word, the uniformity of the action depends then
upon the caprice of the operator.
The arrangement shown at Figure 3, Sheet 2, is an example of this defect. The
top of the generator is represented by A and the two receivers R and R¹, Figure 1,
must be replaced by a receiver R', which is a strong vessel lined with lead and is
fixed to the cover A. A tube S screwed inside and out established a communication
between the two vessels; it is fixed thereto by its external screw, and is provided
with a side opening 7, as shown by the section through X, Y. In the interior
penetrates the rod T, furnished above and below with a similar screw thread; tho
upper part passes through the cover of R¹, so that on turning it by the crank
handle M the rod T rises or descends, and consequently opens the slit more or
less. If then there is a liquid in R' it flows through the opeuing thus made and
so much quicker, supposing the level N, N, to be constant, as the opening is
larger, and if the latter remains constant the flow will be constant also. The whole
question is reduced then to causing the level N, N, to remain constant; this
condition is easily fulfilled by causing the two closed reservoirs R' and R³ to com-
municate by the tube m, m², provided with two taps, one m which is opened
completely to allow the liquid to pass from R³ to R¹, the other m¹ is actuated by a
float F. When the level N becomes lower F descends and opens m³ to the liquid,
the level rises, and F rising also closes m¹; thus the oscillations of the level remain
confined within very narrow limits. The receivers R' and R² must be completely
closed, so that on opening the taps m³ the liquids enclosed therein can be submitted
to the pressure of the generator, without which tho gas from the latter would
prevent the liquids from descending. The small tap m³ serves to allow the air to
escape when the operation is commenced, and m³ closes the funnel by which the
liquid is introduced into R. The water gauge n², n¹, with a glass tube serves to
indicate the progress of the operation.
The following is the method of operating, supposing all the taps to be closed:-
m' is to be opened, and the upper tap of the water gauge n³, the liquid is poured in
through the funnel and gradually fills R2, the air escaping by n' till the level
attains a fixed mark N¹, N¹; m* and n' are then closed. To fill R¹ the three taps
m³, m², and D (Figure 1) are opened,, this latter is the empty tap of the generator
to establish a communication between the air of R and the external atmosphere;
then by placing a funnel m³ the same liquid is introduced as in R³, and in such
"

page_text: quantity that the float quits the bar B, which serves as its support, when m² is
opened. Otherwise this quantity can be determined once for all before placing on
the cover of R', .then at the point V to which the level rises a hole is to be tapped
and closed by a sciew. If this arrangement be adopted it will be sufficient for
filling R', to open m³ and V, and to pour in the liquid at m³, the air escaping by M
until the level is attained; liquid will then flow out, and then m³ must be closed
and V screwed in.
Having performed the same operation in the receivers R' and R², which replace R¹
of Figure 1, to commence the production the two liquids are introduced simul-
taneously into the cup C of the generator by manoeuvring M and M1, the first
portions of gas formed are allowed to escape by the junction pipe 1 to drive the air,,
then this union pipe being put into communication with the washer it will suffice.
to open m³ and m, so that the regular progress of the operation is established.
It is evident that the handles M and M' should be so placed that the liquids
which flow from R and R¹ are, chemically speaking, equivalent to one another. This:
apparatus works automatically, and the more or less rapid production of gas depends:
only on the position given to M.
The following is the passage of the gas produced:-Figure 1. By the junction
tube I it flows into the apparatus represented in section by the side of the generator..
This is a vessel divided into four compartments V, V1, V2, V3, it is in copper covered.
with lead; the tubes and rosettes are made only of lead. The cover, the cylindrical
portion, and the bottom are separate, and are only held together by the two screwed
rods, 21, 2¹, screwing into the bottom; the tightening is effected by the nuts E
and E, bearing upon rings of leather. In order to render the joints air-tight the
cover and the bottom have a thick plate of india-rubber cemented to them, on which
the upper and lower rims of the cylindrical part bear, and thus make a joint After
having opened the tap, which is at x, and unscrewed the screw v, bisulphite of soda
is introduced into the .first compartment V by the upper tube in order to wash
the gas. Chloride of calcium or pumicestone, impregnated with sulphuric acid, is
Then the taps
placed into the three other compartments in the same manner.
,,,, are again closed, and the scrows v, vl, v², v³, are replaced. The sulphurous
gas in its passage will be washed in V, passing through the rosette p; then entering
by o into V will pass through the rosette p¹, and will be dried; then it will pass
into V through o₁, and so on, until its exit os into the worm S, surrounded by a refri-
gerating mixture, where it becomes condensed A small water gauge, the horizontal
branches of which abut upon the coils g and g', indicates in its vertical part
(which is inade of glass) the quantity of liquefied gas which may be drawn off by
the tap L.
When it is only desired to wash the gas before putting the three parts of the
vessel together the opening o is stopped by a screw plug, so that the gas can only
pass out of V by the junction tube, which carries the tap L, by means of which it
passes off to the place where it is to be employed. It will be the same if it be
desired to employ the gas dried and washed, a union joint and tube must then be
screwed into the opening o³ to convey the gas to its destination. The bottom tubes,
carrying taps, situated at y, y¹, y², y³, serve for emptying the respective compart-
ments, either at the end of an operation or during the working, if it be desired to
change the liquid contained in the corresponding compartment. To effect this latter
operation, for example, in the compartment V2 the apparatus A (partly shown, but
with the central portion omitted) must be screwed to the union pipe ³.
Preparation of Liquid Sulphurous Acid.-It is thus very easy to produce liquid
sulphurous acid simply by refrigeration, in causing it to traverse a worm surrounded
by a refrigerating mixture; the only precautions to be taken are to dry the gas pre-
viously, and to cause it to pass slowly through a serpentine of large size. The
liquid sulphurous acid may be also prepared by compression. To prepare the liquid
sulphurous acid by compressing it, by means of a pump, there may be a receptacle
containing this gas, whence it may be taken by the pump, which should compress
it, or, without using a receiver, the sulphurous acid may be taken as quickly as it is
'
B

page_text: made in the generator. It is evident that the production of sulphurous acid gas
must be regulated to the delivery of the pump. However, instead of operating in
this manner it is more convenient to commence by giving a slight pressure in the
generator, and afterwards to take the acid by means of the pump. In this manner
the generator becomes a true gasometer of the sulphurous acid gas, and the pump as
it works always feeds itself, for as the production of sulphurous acid is always going
on the quantity previously formed is held in reserve by giving the pressure. In
order that this operation may be caused to proceed with regularity it is very con-
venient to dry the sulphurous acid before compressing it; in the same manner it is
always useful to surround the vessel wherein the acid is compressed with a refri-
gerating mixture; under these conditions the production of the liquid sulphurous
acid becomes very simple.
Lastly, the liquid sulphurous acid may be prepared in a "Chilorier's" apparatus,
which serves for the liquefaction of carbonic acid. The preparation and distillation
are altogether identical, only that bisulphite of soda is put into the generator, and
sulphuric acid into the copper tube.
Having now described the nature and object of the said Invention for "Improve-
ments in the Preservation of Alimentary Matters, and in Apparatus to be employed
therefor," together with the manner in which the same is to be or may be performed
or carried into practical effect, I would remark in conclusion that I claim as the In-
vention communicated to me by the above-named Alvaro Francisco Carlos Reynoso,
the application and use of the above-described improved processes, and the
apparatus for effecting the preservation of alimentary matters, substantially as
described and as illustrated in the accompanying Drawings.
In witness whereof, I, the said Bristow Hunt, have hereunto set my hand and
seal this Eighteenth day of August, in the year of our Lord One thousand
eight hundred and seventy-six