IMPROVEMENTS IN THE MANUFACTURE OF PRESERVED OR CONDENSED MILK
Year: 1880

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF PRESERVED OR CONDENSED MILK."
A communication from abroad by Edwin Klebs, Doctor of Medicine, and
Professor at the University of Prague, in the Empire of Austria.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 2nd March 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN THE MANUFACTURE OF
PRESERVED OR CONDENSED MILK." [A communication from abroad by Edwin
Klebs, Doctor of Medicine, and Professor at the University of Prague, in the Empire
of Austria.]
This Invention relates to the preservation of milk. According to the said
Invention I form a composition by mixing condensed milk with a solution of a salt
of benzoic acid.
To prepare the preserved milk I take a quantity of raw milk and evaporate or
condense it to about one-fifth (more or less) of its original volume by means of the
common vacuum-condensing apparatus; this takes place at a temperature of
from about 104 to 122 degrees Fahrenheit, and nothing is added to the milk
previously to the commencement of the operation of its condensation by the
evaporation of its water.
While this operation is going forward a solution of a salt of benzoic acid is
gradually added to the milk; this may be done by means of a vessel fitted with an
air-tight cock and easily fixed to any vacuum evaporator.
Amongst the salts of benzoic acid which may be-used I find that benzoate of
magnesia and benzoate of soda are the most suitable. I generally prefer benzoate
of magnesia, and employ a solution of about half a pound of this salt to one gallon
of distilled water. The amount of this addition depends upon the length of time
for which, and amount of the temperature at which, the product has to be kept. If
it be intended to preserve the milk for one month, at least, and at ordinary
temperatures then an addition of the above mentioned solution in the proportion of

page_text: one gallon to one hundred gallons of the original raw milk put into the condensing
apparatus is sufficient.
For longer periods and higher temperatures an addition of the above mentioned
solution in the proportion of two, three, and more gallons to one hundred gallons of
the original unevaporated milk is necessary.
The condensed milk thus treated with the said salt is taken out of the vacuum
apparatus and rapidly cooled down, and finally put into vessels of tin, glass,
porcelain, or other similar materials. These vessels should be previously carefully
cleaned and heated to a temperature of about 250 degrees Fahrenheit in order to
remove all fermentation and to destroy the lower organisms of the fungous class.
The vessels after having been carefully and completely filled are to be closed up so
that the entry of matter inducing fermentation is rendered impossible.
The preserved milk produced possesses at the average temperature of our latitude
the consistency of hard butter, is of a light yellow colour, and has a pleasant
taste and smell not differing from that of fresh milk, with a neutral or weak acid
reaction.
Stirred up with four times its volume of luke-warm water the compound yields
milk of a perfectly equable composition. It is unchanged either in taste or in
appearance when examined microscopically, and its value as food is unimpaired,
while it is scarcely altered in its chemical constitution.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the 30th
August 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN THE MANUFACTURE OF
PRESERVED OR CONDENSED MILK." A communication from abroad by Edwin
Klebs, Doctor of Medicine, and Professor at the University of Prague, in the Empire
of Austria.
This Invention relates to the preservation of milk. According to the said
Invention I form a composition by mixing condensed milk with a solution of a salt
of benzoic acid.
To prepare the preserved milk I take a quantity of milk and evaporate or
condense it to about one fifth (more or less) of its original volume by means of a
common or ordinary condensing apparátus; this takes place at a temperature of
from about 104 to 122 degrees Fahrenheit, and nothing is added to the milk
previously to the commencement of the operation of its condensation by the
evaporation of its water.
While this operation is in progress a solution of a salt of benzoic acid is gradually
added to the milk; this may be done by means of a vessel fitted with an air tight
cock, and easily fixed to any vacuum evaporator.
Amongst the salts of benzoic acid which may be used I find that benzoate of
magnesia and benzoate of soda are the most suitable. I generally prefer benzoate
of magnesia, and employ a solution of about half a pound of this salt to one
gallon of distilled water. The amount of this addition depends upon the length of
time for which, and the degree of temperature at which, the product has to be kept.
If it be intended to preserve the milk for one month, at least, and at ordinary
temperatures, then an addition of the above mentioned solution in the proportion
of one gallon to one hundred gallons of the original raw milk put into the
condensing apparatus is sufficient.
For longer periods and higher temperatures an addition of the above mentioned
solution in the proportion of two, three, and more gallons to one hundred gallons
of the original unevaporated milk is necessary.
The condensed milk thus treated with the said salt is taken out of the vacuum
apparatus and rapidly cooled down, and finally put into vessels of tin, glass,
porcelain, or other similar material. These vessels should be previously carefully
cleaned and heated to a temperature of about 250 degrees Fahrenheit to remove all
fermentation and to destroy the lower organisms of the fungous class. The vessels
after having been carefully and completely filled are to be closed up so that the
entry of matter inducing fermentation is rendered impossible.
The preserved milk produced possesses at the average temperatures in this
latitude the consistency of hard butter, is of a light yellow colour, and has &
pleasant taste and smell not differing from that of fresh milk, with a neutral or
weak acid reaction.
Stirred up with four times its volume of luke-warm water the compound yields
milk of a perfectly equable composition. It is unchanged either in taste or in
appearance when examined microscopically, and its value as food is unimpaired,
while it is scarcely-altered-in its chemical constitution.
Having thus fully described the said Invention, as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,―
First. The compound, consisting of condensed milk in combination with a
solution of a salt of benzoic acid, substantially as above set forth and for the
purpose specified.

page_text: Second. The process for preserving milk, consisting in evaporating the milk to
about one fifth of its volume, then mixing it with a solution of a salt of benzoic
acid, and finally storing the milk so prepared within vessels hermetically closed,
substantially as above described.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Twenty eighth day of August, in the year of our
Lord One thousand eight hundred and eighty.
W. ROBT. LAKE. (L.S.)