IMPROVEMENTS IN THE MANUFACTURE AND PRESERVATION OF BEER, AND IN THE TREATMENT OF YEAST AND WORT, TOGETHER WITH APPARATUS FOR THE
Year: 1873

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE AND PRESERVATION OF BEER, AND IN
THE TREATMENT OF YEAST AND WORT, TOGETHER WITH APPARATUS FOR THE
."-A communication from abroad by Louis Pasteur, of Paris,
France, Chemist, Member of the Institute.
SAME.
Sealed the 9th September 1873, and dated the 25th March 1873.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 25th March 1873.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
3 County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE MANUFACTURE AND PRE-
SERVATION OF BEER, AND IN THE TREATMENT OF YEAST AND WORT, TOGETHER WITH
APPARATUS FOR THE SAME," to be as follows:-
The variations in the condition of brewers' yeast,- worts, and beer are
caused by the presence of microscopic organisms, the development and

page_text: multiplication of which are accompanied by the formation of substances
which change the properties of the wort, beer, or yeast, and also prevent
their keeping beyond a certain time. These organisms exist in varying
proportions in cooled worts as prepared by the ordinary processes, as
well as in yeast and beer.
The object of this Invention is to climinate and prevent the multi-
plication of these organisms by the following means, viz.
1st. Obtaining pure yeast by separating the organic germs foreign to
brewers' yeast.
2ndly. Treating the wort while cooling from the time it leaves the
copper in which all the germs (germs de maladie) are destroyed, until
it reaches the vats, tuns, or fermenting apparatus, and even after fer-
mentation, in such manner that it shall not again receive either by
unlimited contact with the open air, or with the vessels employed, any
pernicious germs capable of multiplying and of subsequently changing
the nature of the products.
3rdly. Cooling in closed vessels in the presence of a limited supply of
filtered air or carbonic acid gas.
Pure yeast, free from pernicious germs, may be obtained in various
ways, among which I will indicate the following:-I take impure yeast,
and cause it to act on a solution of sugar candy in pure water. When
the fermentation is terminated I. decant the fermented liquid, and add a
fresh quantity of sugared water on the top of the yeast deposit. This
operation is repeated two or three times, more or less, according to
circumstances. I then take a shallow porcelain dish, first dipping it in
boiling water, and put in it a little beer wort which has been recently
boiled or preserved by the Appert process. I then dilute a little of the
ycast deposit of the above described fermentation in the wort and cover
it with a glass plate. The yeast which has become more or less
exhausted by its action on the sugared water will then rise and rapidly
revive, purified of its pernicious germs (ferments de maladie). This
treatment may be repeated by diluting a little of the yeast deposited at
the bottom of the first dish in some fresh wort. The degree of purity of
the yeast may be ascertained with the aid of a microscope, which will
indicate the presence of the germs, and show whether, by means of the
yeast, a beer may be produced which shall not vary in condition at any
temperature.

page_text: (In the diagram Figure 1 of the accompanying Drawing the left
half of the Figure shows a pure alcoholic yeast, and the other half an
alcoholic yeast containing the pernicious germs, (which are filiform in
appearance). For this purpose I take a balloon of the form shown in
Figure 2 of any suitable dimensions, and about half fill it with beer
wort which is first rendered unalterable by being boiled in the balloon
itself. The neck A, B, is closed by an india-rubber tube b, c, and a
glass plug C, D. The plug is removed, and one or more drops of the
yeast from the dish diluted with a little of the supernatant liquid is
introduced by means of the tube M, N, which ferments the wort, and
transforms it into beer. If this beer, after remaining some weeks in a
stove having. a temperature of from 70 to 80 degrees Fahrenheit, be
examined under the microscope and no such germs can be perceived, it
will show that the small quantity of yeast introduced was perfectly free
therefrom.. With yeast thus obtained large quantities may be prepared,
it being generated during the manufacture of the beer itself. The yeast
may also be preserved indefinitely in a pure state in contact with pure
air, that is to say, purged of all germs liable to affect the condition of
the yeast, either in an apparatus such as that shown in Figure 2, or
other similar arrangement. It may also be carried long distances
without affecting its condition, and so serve for preparing pure yeast at
all seasons, and in any quantity desired. By this means the brewer will
be spared the necessity of obtaining a fresh supply of yeast from a
brewery when his own has become deteriorated, inasmuch as he has
always yeast at his disposal in an ever pure condition.
The alcoholic yeasts which are properly distinct may also be

page_text: into a stoppered pipe rising from the cover) is connected with the
tube d, e, f, g. Boiling water is then poured on the cover and on thẻ
pipes rising therefrom, which fills the channel, the overflow passing into
a gutter i, i, from which the water escapes through a slit or a number
of small holes in the bottom, and is collected in another gutter at bottom 5
of the cylinder provided with a discharge pipe M. T is a bent
thermometer for indicating the temperature of the wort, the bulb of
which is protected by a perforated guard d, d. R, V, cocks or apertures
for discharging the liquid and sediment from the cylinder. The
cylinder thus filled is allowed to cool by contact of the external air, 1
afterwards assisted if necessary by cold water introduced at the pipe E
on the cover which passes through apertures e, e, and trickles down
The yeast
over the cylinder. Air enters the long tube g, e, f, d, c, a.
is then introduced through the pipe D, which is immediately closed,
the carbonic acid produced during the fermentation passing off at 1
tubef, g. A tube similar to a, c, d, e, f, g, may be adapted to pipe D,
of a different length if desired, for the escape of the carbonic acid gas,
whilst a limited quantity of air is admitted by the other tube. The
wort may be readily cooled in the presence of the carbonic acid gas
by introducing the latter beneath the cover during the cooling. The
tube f, g, may terminate by a loose plug of asbestos or cotton or by a
metal tube heated during the admission of the air. A drop of liquid in
bend g will serve to indicate the movements of the gases.
The apparatus may be greatly varied in form and any apparatus which
will servo to eliminate the pernicious germs derived either from the
air, the raw materials, the yeast, or the apparatus itself, will answer the
purpose.
The employment of purc yeast in the above process is of prime
necessity, that is to say, yeast deprived of the germs by which the beer is
liable to be affected. All kinds of beer manufactured by this process
may be preserved without the aid of ice, and may be made in hot as
well as cold climates, in summer as in winter. As there is no liability
of the worts undergoing any change a very small quantity only of pure
yeast will be sufficient to ferment it.
The following is a recapitulation of the essential features of this
improved process :-The wort is introduced in a boiling state into the
apparatus, on which a cover is then placed, or the cylinder may be
cntirely closed and communicate with the atmosphere only by means

page_text: of the pipes, cocks, and long tubes, with which it is provided. Boiling
water is then thrown on the apparatus, after which it is allowed to cool
with or without the assistance of cold water, during which time air or
carbonic acid gas is admitted by the long tube 9, d, e, f, c, a; but
previous to this one of the pipes on the cover is closed by a plug
through which passes a tube terminating in an india-rubber tube and
glass stopper. Pure wort is then fermented by pure yeast, and when
sufficiently advanced the contents are poured through the tube in the
stopper of the pipe on the cover of the fermenting apparatus. If there
is a supply of pure yeast from the preceding operation this may be
used as in the ordinary processes, the vessel being uncovered for the
purpose if necessary after fermentation has commenced; but this might
lead to great inconvenience at a subsequent period, although the use
of pure yeast manufactured according to this improved process would of
itself form a great improvement on the ordinary processes.
With the aid of the microscope and the method of control before
indicated the changes of condition which might arise under the latter
modes of treatment may be readily ascertained. But onc cooling
apparatus may be used or a few only, the wort being passed into vats
(pitched or varnished on the exterior) which are deprived of any of
the before mentioned germs, either by the use of boiling water or
by a recent coating of pitch on the interior. It will be seen that the
ordinary processes and the improved method may if desired be carried
on simultaneously, so that brewers will be enabled to gradually
transform their plant.
"
After the beer is made any short exposure to the air to which it may
be subjected will have little or no prejudicial effect on its keeping
qualities, and it may also be fined in the usual way.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of March, in the year
of our Lord One thousand eight hundred and seventy-three, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her special
licence that I, the said Alexander Melville Clark, my executors, admi-
nistrators, and assigns, or such others as I, the said Alexander
Melville Clark, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for “IMPROVEMENTS IN THE MANUFACTURE AND PRESERVATION OF BEER, AND IN
THE TREATMENT OF YEAST AND WORT, TOGETHER WITH APPARATUS FOR THE
SAME," a communication to me from abroad by Louis Pasteur, of
Paris, France, Chemist, Member of the Institute, upon the condition
(amongst others) that I, the said Alexander Melville Clark, my exe-
cutors or administrators, by an instrument in writing under my,
or their, or one of their hands and scals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent..
BO
NOW KNOW YE, that I, the said Alexander Melville Clark, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the Sheet
of Drawings hereunto annexed, and to the letters and figures marked
thereon (that is to say) :-
The changes which take place in the yeasts of beer, in worts, and also
in beer itself, are due to the presence of microscopic organisms, whose
developements and multiplication are accompanied by the formation
of substances which alter the nature of the worts, beer, or yeasts, and
which in any case tend to prevent the beer remaining sound beyond a
certain length of time. These organisms are what I term "disease
ferments" or germs of disease, they exist in varying proportions in all
worts prepared and cooled by the methods at present in use as well
as in the yeasts and consequently in all the different kinds of beer.

page_text: The object of this Invention is to suppress in these three products,
yeast, worts, and beer, the existence and mltiplication of these
extraneous ferments or germs by the following means:—
1st. By obtaining a pure yeast by the elimination of organic germs
foreign to the yeast of beer.
"
2nd. By the manipulation of the wort during cooling, from the time
of its leaving the copper, where all the "disease germs are killed, until
it reaches the squares, rounds, or other fermenting apparatus, and even
after fermentation in such manner that it cannot take up, through
coming into unrestricted contact with the atmosphere or with the
utensils, any pernicious germs capable of multiplying themselves and
ultimately of depreciating the product.
3rd. By cooling in closed vessels in the presence of a limited amount
of purified air or of carbonic acid gas.
This new product which I have called "pure leaven" (levain pur), or
yeast freed from extraneous germs may be obtained by various methods
among which I will indicate the following:-I take some impure
(ordinary) yeast and set it to work on a solution of sugar candy in pure
water. When the fermentation has ceased I decant the fermented liquid,
and on the deposit of yeast replace a fresh supply of the sugared water.
This operation is repeated two or three times more or less according to
circumstances. I then take a shallow porcelain tray, such as is used by
photographers, and having previously rinsed it in boiling water I put in
this tray a little beer wort, either recently boiled or preserved in bottles
according to Appert's method, then with this wort I incorporate (by
beating up) a little of the deposited yeast referred to and cover it with.
a glass plate. The yeast more or less exhausted or weakened by its
action on the sugared water will now rapidly develop and revivify itself,
and will be found to be purified of its "disease ferments."
operation with the porcelain tray may be repeated with a second tray,
beating up in fresh beer wort placed in it a little of the yeast formed on
the bottom of the preceding tray. In order to be satisfied of the purity
of the yeast recourse may be had to microscopical examination, which will
readily disclose the presence of "disease ferments" and indicate whether
or not the yeast is capable of producing beer unalterable at all
temperatures.
The

page_text: Figure 1 of the Drawing represents on the left-hand side the appearance
of pure alcoholic yeast, and on the right-hand side an alcoholic yeast
in combination with filiform "disease ferments." To make this
investigation I take a balloon or receiver of the form shown in Figure 2,
of any suitable dimensions, and half fill it or thereabouts with beer wort
which has been rendered inalterable by boiling in the balloon itself.
The neck A, B, of the receiver is closed by an india-rubber tube B, C,
with a glass stopper D. The glass stopper is removed and with the
tube M, N, one or more drops of the yeast from the porcelain tray
shaken or beaten up with a little of the supernatant liquid are introduced
into the apparatus. This yeast multiplies itself, the wort ferments, and
becomes transformed into beer. If this beer when examined under the
microscope, after remaining for some weeks exposed to a temperature of
from 68 to 77° Fahrenheit, shows no trace of the "discase ferments” it
is evident that the small quantity of yeast introduced into the balloon
was itself perfectly free from such ferments. From the "leaven or
yeast so obtained as large a quantity as may be required can be prepared,
the yeast reproducing itself even in the manufacture of the beer. It
may also be indefinitely prescrved in absolute purity in contact with
pure air, that is to say, of air purged of the germs liable to affect the
condition of the yeast by the aid of the apparatus shown in Figure 2, or
of any other vessel fulfilling the same requirements. It may also be
transported any distance without undergoing alteration, and thenceforth
from the same source such yeast may be prepared at all seasons in as
large a quantity as may be desired. This is a great step in the art of
brewing, since it exempts the brewer from the necessity of having
recourse to the yeast of other breweries more or less remote when his
own becomes deteriorated, and places at his disposal one that is pure
and unalterable.
"

page_text: top by a cover, the rim of which projects downwards into a channel
around the top of the vessel filled with water, and provided with a cock r.
The beer wort, properly so called, or any other wort suitable for the
manufacture of -beer, is first boiled in the copper, and in this condition is
conducted into the cylinder, which may be completely filled, and the lid
is then put on; then by means of the india-rubber tube c, d, the metal
pipe a, c, (opening into a stoppered pipe or socket rising from the cover)
is connected with the tube d, e, f, g. Boiling water is then poured over
the lid and socket pipes and their stoppers, filling the channel, the over-
flow passing into a gutter i, i, from which the water escapes through a
slit or a number of small holes, and flows down outside the vessel, and is
collected in a lower gutter provided with a discharge pipe at M.
T is a
bent thermometer to indicate the temperature of the wort, its bulb being
protected by a perforated guard d, d; R, V, are cocks or valves for the
discharge of the liquid from the cylinder, and the deposit formed in it.
I leave the apparatus thus filled to become cooled by contact with the
external air, aided afterwards, if thought expedient or useful, by the
application of cold water introduced at the larger pipe E on the cover,
which is allowed to flow through apertures at e, e, and trickles down
over the vessel. The external air enters through the long tube g, f, e,
d, c, a, during the whole of the period occupied in cooling, and when
that is accomplished the yeast is introduced through the pipe D, which
is at once closed, the carbonic acid gas disengaged during the fermentation
passing off through the tube f, g. A tube similar to the tube a, b, c, d,
e, f, g, may be adapted to the socket pipo D, if desired, of a different
length to admit of the escape of the carbonic acid gas, whilst a limited
quantity of air is admitted by the other tube. The wort also may readily
be cooled in the presence of carbonic acid gas by causing the gas to be
introduced beneath the cover during the refrigeration. The tube f, g,
may end with a loose plug or stopper of asbestos, cotton, or by a
metallic tube, made hot during the admission of the air. A small
quantity of liquid in the bend will serve to indicate the movement of
the gas.
The form of this apparatus may be varied considerably, but any
apparatus which will serve to eliminate the germs of disease imparted
by the atmosphere, by the raw materials, by the yeast, or by the utensils
will answer the purpose. This process imperatively demands the
employment of a yeast absolutely pure, that is to say, deprived of those
germs of disease by which beer is liable to be affected. Any beers made

page_text: by this process may be preserved without the employment of ice, and
may be manufactured with as much facility in hot countries as in cold,
in summer as well as in winter. As no alternation is to be feared in the
wort a very small quantity only of the pure yeast will be sufficient to
ferment it.
The following is a recapitulation of the successive steps essential to
this process:-The wort is introduced in a boiling state into the
apparatus, on which a cover is then placed, or the cylinder may be
entirely closed, and communication with the atmosphere need only take
place by means of the socket pipes, the cocks, or the long tubes with
which it is provided. Boiling water is then thrown over the apparatus,
as previously described, after which it is allowed to cool, either with or
without the application of cold water, whilst through the long tube g, d,
e, f, c, a, air or carbonic acid gas is admitted, one of the socket pipes on
the cover having been previously closed by a stopper through which
passes a tube terminating in an india-rubber tube having a glass stopper.
Some pure beer wort is also set to ferment with pure yeast, and when
the fermentation is fairly established or more or less accomplished, the
contents are poured through the tube, which passes through the stopper
of the socket pipe on the cover of the apparatus.
If the brewer has already some pure yeast from a previous operation,
it can be used exactly as in the ordinary manner, uncovering the vat if
necessary, after the fermentation has begun, though this mode of pro-
cedure may possibly lead to grave ulterior disadvantages. Nevertheless,
it would have the effect of greatly improving the existing method of
working if this new process were employed only so far as the use of
pure yeast is concerned.
By the microscope and the means of control I have previously
indicated the alterations which may or can ensue upon the employment
of these last methods of working may be readily ascertained.
Only one refrigerator or cooler is absolutely necessary, or at most a
few coolers only, the wort being passed into vats or casks which have
been deprived of the germs of disease, either by the application of boiling
water (the pitching or varnishing being external), or by the recent
pitching of the interior.)
It will be seen that the existing process of brewing and this new
method may be carried on simultaneously in a manner that will enable

page_text: brewers to gradually alter and transform their plant and utensils as
circumstances may permit.
When the beer is made, neither its exposure to the air during a more
or less extended manipulation, nor fining under the ordinary system will
have little or any prejudicial effect on its ulterior keeping qualities.
Having described the nature of the said Invention, and the manner in
which the same is to be performed, I declare that what I claim as the
Invention to be protected by the hercin-before in part recited Letters
Patent is,-
1st. The adaptation to brewing of the following combination of
processes, methods, or means, and each of them specially, viz., the
obtaining of a pure leaven or yeast by the elimination of the organic
germs foreign to the yeast of beer; the methodic and special manner of
manipulation of the wort during cooling from the time of its leaving the
copper (in which all the germs of disease are destroyed), to the vessels
in which fermentation is induced, in such manner that it cannot become
reimpregnated with pernicious germs derived from unlimited contact
with the air or of the utensils employed; the cooling in a closed vessel
in presence of carbonic acid gas, or in presence of air purified and limited
in quantity, all substantially as herein described.
2nd. The apparatus or means by which these processes entirely or
partially may be carried out in practice, substantially as specified.
3rd. The obtention by these processes and means of the improved
products herein specified, viz., beer unalterable in character, pure yeast,
or pure wort, substantially as described; all three products being capable
of transport to any distance without alteration or deterioration.
In witness whereof, I, the said Alexander Melville Clark, have here-
unto set my hand and seal, this Twenty-fourth day of September,
in the year of our Lord One thousand eight hundred and seventy-