An Improved Method of and Apparatus for Preserving Milk.
Year: 1889

page_text: Date of Application, 30th Nov., 1889
Complete Specification Left, 1st Sept., 1890-Accepted, 8th Nov., 1890
PROVISIONAL SPECIFICATION.
An Improved Method of and Apparatus for Preserving Milk.
A communication to me from abroad by AUGUST SEIDENSTICKER, of Wülfel, in the
Empire of Germany.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent. Agents and
Engineers, of 35, Southampton Buildings, Chaucery Lane, in the County of
Middlesex do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved method of and apparatus for preserving milk.
To preserve milk for several days in a good state and with the natural colour and
Hlavour of the fresh milk, the known method and apparatus of Pasteur has hereto-
fore ouly been used, but the results thereby obtained are far from being satisfactory.
In many cases, the milk has remained in a good state during a decidedly longer
term than usual, but in other cases, though having been treated exactly in the
same manner and by the same apparatus it has become spoiled in a very short
time. Accordingly the usual method of pasteurisation having failed to be reliable
could not be used with confidence by the dairy trade. The inefficiency of the usual
apparatus of pasteurisation consists mainly in the fact that it provides no means for
exactly controlling the degree of temperature, to which the particles of milk are
heated, nor the extent of time during which a determined temperature continues to
act on each particle of milk in the mass. Another defect consists in the fact that
the cooling apparatus and the jars or cans for preserving and transporting the milk
though carefully cleaned and rinsed, have never been sterilized before being used in
order to destroy any germs or bacteria therein contained.
Owing to these defects the milk, when drawn from the heating apparatus, still
contains a sufficient quantity of ferment not destroyed by heat or such ferments reach
the milk whilst passing the cooler or while preserved in the jars. According to the
variable number of such ferments or bacteria remaining in the pasteurised milk, the
latter will become spoiled in a shorter or longer time.
Owing to the want of control and uncertainty of temperature with the existing
apparatus, any morbific matter contained in the milk will be destroyed with as little
reliability as is the case with the ferments.
An apparatus for pasteurisation from which a thorough success could be expected
should answer the following requirements:-
1. The morbific matter, which may be contained in the milk, should be reliably
destroyed.
2. The fermentative matter contained in the milk should be likewise destroyed as
completely as possible, and the bacteria or germs which still continue living in the
milk must be so small in number and of such kind, that they can only very slowly
exert deteriorating influence on the bulk of milk under treatment.
3. From the moment of drawing off the milk from the heating apparatus to the
moment of sale, no opportunity must be allowed for admitting fermentative or morbific
matter into the milk.
4. The temperature to which the milk is heated ought, in general. not to exceed
70 to 75° C.. and such heat ought not to continue beyond a determined length of
time, otherwise, the flavour of the milk would change and the condition could not be
fulfilled, that the preserved or pasteurised, milk should not betray any remarkable.
difference when compared with fresh milk, with which it is to compete.
5. Large quantities of milk must be treated within a limited space of time.
6. The working of the process and apparatus must be capable of being readily
understood and carried on by any persons of no particular skill or experience.
It has been found by Professor Fluegge, of Breslau, that morbific matter will be

page_text: positively destroyed by a heat of 69° C., continued for 30 minutes or by heating up
to 75° C. continued for 15 minutes, or by heating up to 96° C. continued for
10 minutes. Under the same scale of temperature and respective extent of time during
which it works, any fermentative matterwhich may be present in the treatment of milk,
will be destroyed with equal certainty, as the said Professor Fluegge has ascertained
by experiments, partly of scientific bacteriological character, partly by practical
experience with the preservation of milk. It has been found that under the con-
ditions hereinafter more fully described of sterilization of the vessels, the milk,
having been heated to 69° C. through 30 minutes, or to 75° C. through 15 minutes,
will remain fresh and in a good state for sale through at least 65 hours, at an
outside temperature of 16° U., and through 36 hours at an outside temperature
of 22 to 24° C. and through 20 hours at an outside temperature of 32° C. This milk
will shew not the least difference from fresh milk, as regards flavour, smell, appearance
and yield of cream or butter.
In the case of very high outside temperature (beyond 25 to 30° C.) it will be
necessary to apply a greater heat, up to 95 and 96° C., and to continue the same
for 10 to 15 minutes in order to preserve the milk for two days. In this case the
flavour of the milk indeed would be impaired, but this will be of little consequence,
because, during such high temperature in summer fresh milk is but rarely used.
To prevent the subsequent infection of the milk after pasteurisation, by fermenta-
tive matter the only reliable means consist in sterilizing all vessels and objects with
which the milk after pasteurisation, will have to come in contact particularly the
cooling apparatus and jars or cans used in transport.
The most effective, convenient and cheapest means to attain this object is the
application of steam from a steam boiler such application being hereinafter more
fully described.
Having thus explained the leading principle of the present invention, I will now
proceed to describe the mode of performing the same in such a manner as to answer
the above stated desiderata and particularly those given under 5 and 6..
It might appear that the most simple and convenient means of pasteurization would
consist in subjecting the milk to the required heat while enclosed in the jars or cans
in which it is carried, thereby avoiding any subsequent contact of the pasteurised
milk with the surrounding atmosphere. But to proceed in this manner would not
lead to success, because the milk so treated would undergo a material change of
appearance and flavour as compared with fresh milk.
To carry the improved method of preserving milk into practice, the following
apparatus will be employed.
A steam boiler is required which produces per hour about 35 kilogrammes of
steam superheated to one atmosphere, for every hectolitre of milk to be treated.
The heating apparatus consists of a boiler of tinned copper provided with a
suitable cover; within the said boiler a coiled pipe of tinned copper is arranged the
lower end of which coil communicates through a connecting pipe with another inner
coil of a smaller size, which coil at its upper end communicates with a third inner
coil of the same diameter of pipe. The lower end of the third coil extends through
a stuffing box in the bottom of boiler to carry off the waste steam and water of
condensation. To the connecting pipe between the second and third coils another
branch pipe is jointed. leading also down through a stuffing box in the bottom,
the said pipe being provided with a cock to draw off the water of condensation.
Between the first and second coils and inside the third coil agitators are provided,
the central one being directly connected to a vertical shaft and the outside ones being
carried by vertical rods connected to crossbars carried by the same shaft.
The lower end of the shaft rests in a foot step and at its upper end it has a collar
carried by the frame of the apparatus. Motion is imparted to the shaft by a shaft
and handle or by pullies and bevel gear.
The steam coming from the steam boiler through suitable pipes is admitted to the
first coil through an elbow pipe arranged to be disconnected when desired.
The steam passes down through the coil, theu euters through the connecting pipe

page_text: into the second coil from the upper end of which it passes down again through the
third coil and escapes through the end of the pipe projecting below the boiler.
The coils are jointed to each other by flanges so as to be easily disconnected and
removed, for the sake of cleaning; also the shaft is preferably made in two lengths
coupled together, to facilitate the removal and cleaning of the agitators.
The milk having been filled into the boiler is intimately mixed and stirred by
the agitators, for the purpose of maintaining a uniform temperature throughout the
mass contained in the boiler. A cock is provided in the bottom of the boiler to
draw off the milk when sufficiently heated; the said cock is arranged immediately
below the bottom, to avoid dead space, within which part of the milk might remain
out of reach of the necessary influence of heat. Such parts of the milk being
insufficiently pasteurised would afterwards communicate the germs and ferments still
remaining in it to the pasteurized bulk of the milk and infect the same.
At the lower end of the boiler a thermometer is suitably arranged, extending into
the boiler up to the space between the first and second coils and thus indicating the
average temperature of the milk contained in the boiler.
After the heating operation, the milk is drawn off into cooling apparatus preferably
upon the known system of Schmidt of Bretten consisting of a vessel with a discharge
cock. within the said vessel a corrugated cylinder being arranged communicating
with a water feed pipe. The water admitted by the said pipe into the circular space
between the cylinder and another concentric one rises within the said space and runs
off through a pipe leading down from the upper end of the first cylinder. The milk
being distributed by suitable distributing apparatus runs down the corrugated surface
of the second cylinder and is collected in a sufficiently cooled state in the lower part
of the vessel from which it is drawn off through the cock into jars or cans.
Before the beginning of every cooling operation the cooler is subjected to a
sterilizing treatment. To perform the same the cooler is covered by a bell and the
cock is connected with a steam pipe. On opening the cock, the steam enters and
spreads round all the surface of the cooling apparatus, including the distributor.
destroying any germs and fermentable matter and escaping through an aperture at
the top of the bell.
1
The jars or cans destined to receive the pasteurised milk and to preserve and convey
the same for sale, have a closely fitting lid or stopper through which two tubes of
about 2 centimetres diameter extend; .to one of the said tubes an extension tube may
be secured reaching down to the bottom of the jar or can for the purpose of con-
ducting the steam completely down when connected to the tube. The jar or can
having been sterilized by the heat of the steam, the milk is filled into it from the
cooler and the tubes are then tightly closed by screw stoppers.
The working process in treating the milk according to the improved method of this
invention is carried on as follows, with the set of apparatus before described.
First, the heating coils are jointed to each other and fitted into the boiler, then
the agitators are loosely put in position the cover closed and the thermometer inserted
into its seat. Then the discharge pipe is connected to a steam feed pipe and steam
let into the boiler for the purpose of sterilizing the inside surfaces of the heating
boiler and the outside surface of the coils agitators and shaft. The steam continues
for about 5 minutes at a high pressure of about 2 atmospheres, and escapes through
the interstices between the shaft and the lid and between the connecting pipe and the
lid. Experience has shewn that the action of steam, continued for 5 minutes as
before stated, is sufficient to effect a complete sterilization. After which the steam is
cut off, the lid of the boiler opened and sufficient milk poured into it to cover the
upper ends of the heating coils. Then the lid is again put on, the connecting pipe
jointed to the coil, the shaft of the agitator coupled to the driving shaft and motion
imparted to the driving gear. Steam is now let into the coils aud the milk becomes
rapidly heated, under continued agitation. The water of condensation running off
from the coils, has nearly the same temperature as the surrounding milk, proving that
the heat of the steam is fully utilized. When the determined maximum temperature.
say 69° C. has been attained, which will take about 12 to 15 minutes the steam is

page_text: shut off. As soon as the thermometer begins to fall, which will be the case in a few
minutes, the steam valve is partly opened, and after a little experience the amount of
opening will be found and maintained for the future operations, to keep the tempera-
ture at the constant level, say 69° C. for the desired length of time.
In general the period of keeping heated the milk to 69° C. will be 30 minutes.
With poor milk containing generally a larger amount of germs, it is better to apply
a greater heat, up to 75° C. and to continue the same for 15 minutes.
The same
increase of heat is preferably employed with good milk if the outside atmosphere is
high. During very hot summer time, the temperature exceeding 30° C. it will be
expedient to heat the milk of both kinds up to 96° C. during 10 to 12 minutes.
During the time of heating the milk the steam boiler delivers but little steam to
the heating apparatus and the surplus of steam produced, may during that time be
employed for sterilizing the cooler and the milk jars or cans. To perform the said
sterilization, the exhaust cock of the cooler is connected to a steam feed pipe the bell
having first been put over the cooler and the water pipe jointed. The steam being
turned on continues for 5 minutes to sterilize all the surfaces with which the milk
enters into contact during the cooling operation. While the steam is passing, a
wooden rod or stirrer is introduced into an aperture at the top of the bell for the
purpose of sterilizing the said rod, which afterwards serves to distribute the milk while
running into the cooler.
The sterilization of the cooling apparatus being completed, the steam pipe is dis-
connected and water turned on to cool the same down.
To sterilize the milk jars or cans, the tube of the lid is connected with the steam
feed pipe and steam is let in, passing down through the extension tube to the bottom
and escaping through the escape tube. The heating operations having continued
for 5 minutes, the steam is shut off, the steam pipe disconnected and another jar or
can coupled to the same. By this means, all the jars or cans may be sterilized in
quick succession. As they are treated the cover of each is immediately raised, the
extension pipe withdrawn the condensed water poured out and the cover put tightly
on again.
When the milk in the boiler has been heated for a sufficient length of time to
the desired degree, the steam is shut off and the cooler, after the bell has been
removed, placed below the valve cock.
The
The first litre of milk running from the said, cock is preferably put aside, instead
of feeding it into the cooler, because in the first portion, which has remained in the
cock, there is still some possibility of the presence of fermentative germs.
further quantity of milk contained in the boiler is all run into the cooler, distributing
the same, in the course of feeding, by the wooden rod previously sterilized as before
described. From the cooler the milk is drawn off into the jars or cans, each of
which having been filled is hermetically closed by screwing plugs upon the upper ends
of the tubes, the said plugs may preferably be sterilized by heat, immediately before
being used.
During all the operations described great care ought to be taken to avoid any
contact of the cooling surfaces, the inside surfaces and the cover and stoppers of the
jars or cans with the hands of the operator, or with implements not sterilized, such
as might afterwards carry germs into the pasteurised milk.
The boiler having been emptied may at once he charged again with a fresh
quantity of milk to be treated in the manner described, while the cooler liad better
be submitted to the described sterilization after every time it has been used.
The time occupied by preparing a given quantity of milk according to the improved
method will be as follows, provided the size of the apparatus he appropriate to the
quantity:
a, heating the milk within the boiler up to the desired temperature of 69, or 75,
or 96° C.. will take respectively 10, 15 and 20 minutes.
b. keening the milk heated to the desired degree respectively 30, 15, or 10 minutes,
c. cooling the milk, 20 minutes,

page_text: When the whole quantity of milk has been treated, the heating apparatus is filled
up with water and heated, by the admission of steam into the coils up to 60 to 70° C.
making an addition of 1 kilogramme of carbonate of soda, to 100 litres of water.
The crust deposited on and adhering to the coils will be thus entirely softened and
may be readily removed by a brush. The coils can readily be removed from the
boiler for the purpose of better cleaning them. The cooling apparatus and jars or
cans after use, are also cleaned with a hot solution of carbonate of soda and
subsequently rinsed with pure water.
Dated this 30th day of November 1889.
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicant.
A communication to me from abroad by AUGUST SEIDENSTICKER, of Wälfel, in the
Empire of Germany.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of
Middlesex, 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, and accompanying drawing, that is to say:-
This invention relates to an improved method of and apparatus for preserving
milk.
To preserve milk for several days in a good state and with the natural colour and
flavour of the fresh milk, the known method and apparatus of Pasteur has heretofore
only been used, but the results thereby obtained are far from being satisfactory, in
many cases the milk has remained in a good state during a decidedly longer
term than usual, but in other cases though having been treated exactly in the
same manner and by the same apparatus, it has become spoiled in a very short
time.
Accordingly the usual method and apparatus of pasteurisation having failed to be
reliable could not be used with confidence by the dairy trade. The inefficiency of the
usual apparatus of pasteurisation consists mainly in the fact that it provides no means
for exactly controlling the degree of temperature to which the particles of milk are
heated, nor the exact extent of time during which a determined temperature continues
to act on each particle of milk in the mass.
Another defect consists in the fact that the cooling apparatus and the jars or cans
for preserving and transporting the milk though carefully cleaned and rinsed, have
never been sterilized before being used, in order to destroy any germs or bacteria
contained therein. Owing to these defects, the milk when drawn from the heating
apparatus still contains a sufficient quantity: of ferment not destroyed by heat
or such ferments reach the milk while passing the cooler or while preserved in the
jars. According to the variable number of such ferments or bacteria remaining
in the pasteurised milk the latter will become spoiled in a shorter or longer
time.
•
Owing to the want of control and uncertainty of temperature with the existing
apparatus any morbific matter contained in the milk will be destroyed with as little
reliability as is the case with the ferments.
An apparatus for pasteurisation from which a thorough success could be expected,
should answer the following requirements:
1. The morbific matter, which may be contained in the milk should be reliably
destroyed.
2. The fermentative matter contained in the milk should be likewise destroyed as
completely as possible and the bacteria or germs which still continue living in the

page_text: milk must be so small in number and of such kind that they can only very slowly
exert a deteriorating influence on the bulk of milk under treatment.
3. From the moment of drawing off the milk from the heating apparatus to the
moment of sale, no opportunity must be allowed for admitting fermentative or morbific
matter into the milk.
4. The temperature to which the milk is heated ought in general not to exceed
70° to 75° C, and such heat ought not to continue beyond a determined length of
time otherwise the flavour of the milk would change and the condition could not
be fulfilled that the preserved or pasteurised milk should not betray any
remarkable difference when compared with fresh milk with which it is to
compete.
5. Large quantities of milk must be treated within a limited space of time.
6. The working of the process and apparatus must be capable of being
readily understood and carried on by any persons of no particular skill
experience.
or
It has been found by Professor Fluegge, of Breslau, that morbific matter will be
positively destroyed by a heat of 69° C., continued for 30 minutes, or by heating up
to 75° C. continued for 15 minutes, or by heating up to 96° C. continued for
10 minutes. Under the same scale of temperature and respective extent of time
during which it works, any fermentative matter which may be present in the treatment
of milk will be destroyed with equal certainty as the said Professor Fluegge has
ascertained by experiments, partly of scientific bacteriological character, partly by
practical experience with the preservation of milk. It has been found that under the
conditions hereinafter more fully described of sterilization of the vessels the milk
having been heated to 69° C. through 30 minutes, or to 75° C. through 15 minutes,
will remain fresh and in a good state for sale through at least 65 hours, at an outside
temperature of 16° C., and through 36 hours at an outside temperature of 22 to 24° C.,
and through 20 hours at an outside temperature of 32° C. This milk will show not
the least difference from fresh milk as regards flavour, smell, appearance and yield of
cream or butter.
In the case of very high outside temperature (beyond 25 to 30° C.) it will be
necessary to apply a greater heat up to 95 and 96° C., and to continue the same
for 10 to 15 minutes, in order to preserve the milk for two days.
In this case.
the flavour of the milk, indeed, would be impaired but this will be of little
consequence, because, during such high temperatures in summer fresh milk is
but rarely used.
To prevent the subsequent infection of the milk after pasteurisation by fermentative
matter the only reliable means consists in sterilizing all vessels and objects with which
the milk, after pasteurisation will have to come in contact, particularly the cooling
apparatus and jars or cans used in transport.
The most effective convenient and cheap means to obtain this object is the application
of steam from a steam boiler and such application being hereinafter more fully
described.
Having thus explained the leading principle of the present invention I will now
proceed to describe the mode of performing the same in such a manner as to answer
the above stated desiderata and particularly those given under 5 and 6.
It might appear that the most simple and convenient means of pasteurisation would
consist in subjecting the milk to the required heat while enclosed in the jars or cans
in which it is carried thereby avoiding any subsequent contact of the pasteurised milk
with the surrounding atmosphere. But to proceed in this manner would not lead to
success because the milk so treated would undergo a material change of appearance
and flavour as compared with fresh milk.
To carry the improved method of preserving milk into practice the following
apparatus will be employed, as shewn in the accompanying drawing which is in
illustration of the invention.
Figure 1 is a central vertical section through the heating boiler,
Th:
sential section at right angles to Ticuro 1

page_text: Figure 3 is a plan of the heating apparatus or boiler,
Figure is a central vertical section of the cooling apparatus and
Figure 5 is a central vertical section of a milk jar for preserving and conveying the
milk when treated according to the improved method.
A steam boiler not shown in the drawing is required which produces per hour
about 35 kilogrammes of steam superheated to 1 atmosphere for every hectolitre of
milk to be treated.
The heating apparatus consists of a boiler A of tinned copper provided with a
suitable cover, within the said boiler A a coiled pipe B of tinned copper is arranged,
the lower end of which coil communicates through a connecting pipe C with another
coil D of a smaller size, which coil D at its upper end communicates with a third
inner coil E of the same diameter of pipe. The lower end of the third coil E extends
through a stuffing box in the bottom of the boiler A to carry off the waste steam and
water of condensation. To the connecting pipe C between the second and third coils
another branch pipe F is jointed, leading also down through a stuffing box in the
bottom, the said pipe F being provided with a cock to draw off the water of
condensation. Between the coils B and D and inside the coil E agitators are
provided, the central one being directly connected to a vertical shaft G and the
outside ones being carried by vertical rods connected to cross bars J carried by the
same shaft G.
The lower end of the shaft G rests in a foot step and at its upper end it has a
collar K carried by the frame of the apparatus. Motion is imparted to the shaft by a
shaft and handle M or by pullies and bevel gear L L'.
The steam coming from the steam boiler through suitable pipes is admitted to the
first coil B through an elbow pipe N Figures 2 and 3, arranged to be disconnected
when desired. The steam passes down through the coiled pipe B then enters through the
connecting pipe C into the second coil D, from the upper end of which it passes
down again through the third coil E and escapes through the end of the pipe
projecting below the boiler A.
The coils B D and E are jointed to each other by flanges so as to be easily dis-
connected and removed for the sake of cleaning, also the shaft G is preferably made
in two lengths coupled together, to facilitate the removal and cleaning of the
agitators.
At the
The milk having been filled into the boiler A is intimately mixed and stirred by
the agitators, for the purpose of maintaining a uniform temperature throughout the
mass contained in the boiler. A cock is provided in the bottom of the boiler A
to draw off the milk when sufficiently heated. The said cock is arranged immediately
below the bottom to avoid dead space within which part of the milk might remain
out of reach of the necessary influence of heat. Such parts of the milk being
insufficiently pasteurised would afterwards communicate the germs and ferments still
remaining in it, to the pasteurised bulk of the milk, and infect the same.
lower end of the boiler A a thermometer P is suitably arranged extending into the
boiler up to the space between the coils B and D and thus indicating the average
temperature of the milk contained in the boiler. After the heating operation, the
milk is drawn off into the cooling apparatus preferably upon the known system of
Schmidt of Bretten, as represented in Figure 1. The said cooling apparatus consists
of a vessel Q with a discharge cock Q', within the said vessel Q a corrugated cylinder
being arranged, communicating with a water feed pipe R. The water, admitted by
the said pipe into the circular space between the cylinders R and R2, rises within
the said space and runs off through a pipe R³ leading down from the upper end
of the cylinder R. The milk being distributed by the distributing apparatus S runs
down the corrugated surface of the cylinder Rand is collected in a sufficiently
cooled state in the lower part of the vessel Q from which it is drawn off through the
cock Q into the jars or cans.
Before the beginning of every cooling operation, the cooler Figure 4 is subjected
to a sterilizing treatment. To perform the same the cooler is covered by a bell T and

page_text: the cock Qis connected with a steam pipe. On opening the cock, the steam enters
and spreads round all the surface of the cooling apparatus, including the distributor S,
destroying any germs and fermentable matters and escaping through an aperture T
at the top of the bell. The jars or cans shown in Figure 5 destined to receive the
pasteurised milk and to preserve and convey the same for sale, have a closely fitting
lid or stopper through which two tubes V VI of about two centimetres diameter
extend, to one of the said tubes an extension tube V may be secured reaching down
to the bottom of the jar or can for the purpose of conducting the steam completely
down when connected to the tube V. The jar or can having been sterilized by the
heat of the steam the milk is filled into it from the cooler Q whereupon the tubes V V¹
are then tightly closed by screw stoppers W.
The working process in treating milk, according to the improved method of this
invention is carried on as follows with the set of apparatus before described.
'
First, the heating coils are jointed to each other and fitted into the boiler A, then
the agitators are loosely put in position, the cover closed and the thermometer P
inserted into its seat. Then the discharge pipe 0 is connected to a steam feed pipe
and steam is let into the boiler for the purpose of sterilizing the inside surfaces of the
heating boiler A and the outside surface of the coils, agitators and shaft. The steam
continues for about 5 minutes at a high pressure of about 2 atmospheres, and escapes
through the interstices between the shaft G and the lid and between the connecting
pipe N and the lid. Experience has shown that the action of steam continued for
5 minutes as before stated, is sufficient to effect a complete sterilization. After which
the steam is cut off, the lid of the boiler A opened and sufficient milk poured into it to
cover the upper ends of the heating coils. Then the lid is again put on, the connecting
pipe N jointed to the coil B. the shaft of the agitator coupled to the driving shaft and
motion imparted to the driving gear. Steam is now let into the coils B D E and the
milk becomes rapidly heated, under continued agitation. The water of condensation,
running off from the coils, has nearly the same temperature as the surrounding milk
proving that the heat of the steam is fully utilized. When the determined maximum
temperature, say 69° C., has been attained, which will take about 12 to 15 minutes,
the steam is shut off.
As soon as the thermometer begins to fall, which will be the case in a few minutes,
the steam valve is partly opened and after a little experience the amount of opening
will be found and maintained for the future operations, to keep the temperature at the
constant level, say 69 degrees for the desired length of time.
In general the period of keeping the milk heated to 69° C. will be 30 minutes.
With poor milk containing generally a larger amount of germs, it is better to apply a
greater heat, up to 75° C., and to continue the same for 15 minutes.
The same
increase of heat is preferably employed with good milk, if the outside atmosphere is
high. During very hot summer time the temperature exceeding 30° C., it will be
expedient to heat the milk of both kinds up to 96° C. during 10 to 12 minutes.
During the time of heating the milk, the steam boiler delivers but little steam to
the heating apparatus and the surplus of steam produced, may during that time be
employed for sterilizing the cooler and the milk jars or cans.
To perform the said sterilization the exhaust cock Q¹ of the cooler is connected to a
steam feed pipe, the bell T having first been put over the cooler and the water pipe
jointed. The steam being let in, continues for 5 minutes to sterilize all the surfaces
with which the milk enters into contact during the cooling operation. While the
steam is passing, a wooden rod or stirrer is introduced into an aperture T at the top
of the bell, for the purpose of sterilizing the said rod which afterwards serves to
distribute the milk while running into the cooler. The sterilization of the.cooling
apparatus being completed, the steam pipe is disconnected and water turned on to cool
the same down. To sterilize the milk jars or cans the tube VI of the lid is connected
with the steam feed pipe and steam is let in passing down through the extension
tube V2 and escaping through the tube V. The heating operation having continued
for 5 minutes the steam is shut off the steam pipe disconnected and another jar or cau

page_text: coupled to the same.
By this means all the jars or cans may be sterilized in quick
succession. As they are treated the cover of each is immediately raised, the extension
pipe V withdrawn the condensed water poured ont and the cover put tightly on again.
When the milk in the boiler A has been heated for a sufficient length of time to the
desired degree the steam is shut off and the cooler, after the hell T has been removed
placed below the valve cock 0. The first litre of milk running from the said cock is
preferably put aside, instead of feeding it into the cooler, because in the first portion
which has remained in the cock, there is still some possibility of the presence of
fermentative germs. The further quantity of milk contained in the boiler A is all run
into the cooler, distributing the same, in the course of feeding, by the wooden rod
previously sterilized, as before described. From the cooler Q the milk is drawn off
into the jars or cans each of which having been filled is hermetically closed by screwing
plugs W upon the upper ends of the tubes V V₁, the said plugs may preferably be
sterilized by heat, immediately before being used.
During all the operations described great care ought to be taken to avoid any
contact of the cooling surfaces the inside surfaces and the cover and the stoppers of
the jars with the hands of the operator, or with implements not sterilized such as might
afterwards carry germs into the pasteurised milk.
The boiler A having been emptied may at once be charged again with a fresli
quantity of milk to be treated in the manner described, while the cooler had better be
submitted to the described sterilization after every time it has been used.
The time occupied by preparing a given quantity of milk according to the
improved method will be as follows," provided the size of apparatus be appropriate to
the quantity.
a, heating the milk within the boiler A up to the desired temperature of 69, or 75,
or 96° C., will take respectively 10, 15 and 20 minutes.
b, keeping the milk heated to the desired degree respectively. 30, 15 or 10 minutes.
e, cooling the milk 20 minutes.
Total about 1 hour.
When the whole quantity of milk has been treated, the heating apparatus is filled
up with water and heated, by the admission of steam into the coils, up to 60 to 70° C..
making an addition of 1 kilogramme of carbonate of soda, to 100 litres of water. The
crust deposited on and adhering to the coils will be thus entirely softened and may be
readily removed by a brush. The coils can be readily removed from the boiler for the
purpose of better cleaning them. The cooling apparatus and jars or cans after use,
are also cleaned with a hot solution of carbonate of soda and subsequently rinsed with
pure water.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. The method of preparing milk for preserving the same during several days and
for eliminating all morbific germs, by the combination of the following operations, viz. :
a) Heating the milk, in a considerable quantity, up to a determined temperature,
keeping the same heated to such temperature for an exact length of time, and
subsequently cooling the milk.
b) Sterilizing the heating apparatus, the cooling apparatus, and the jars destined
to receive the prepared milk.
2. The apparatus for heating (pasteurising) the milk, consisting of an open boiler
with a double heating coil pipe to be heated by steam, in combination with a suitable
agitator.
3. The method of sterilization of the cooling apparatus by covering the same with a
bell T and introducing heated steam.
4. The method of sterilizing the milk jars destined to receive the prepared milk, by

page_text: introducing heated steam through suitable tubes provided in the lid of the jar, and
subsequently tightly closing the said tubes by suitable screw stoppers, all substantially
as and for the purposes set forth and shown in the drawing.
Dated this 30th day of August 1890.
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicant.