the moment when it is pitched, yet fail to produce a beer which shall be
bright when racked, or one that will brighten subsequently otherwise
than with great difficulty. We may add that when we repeated this same
experiment, cooling the wort, however, as rapidly as the conditions of
our apparatus permitted, and employing iced water, the beer appeared
very nearly bright when it was racked, and brightened pretty quickly in
cask and in bottle. The total duration of cooling was not longer than
two hours.
The question here arises what part does the oxygen combined with wort
play in the clarification of the latter, or in the clarification of
beer? Although it may be difficult to give a definite answer to this
question, we must bear in mind that in cases where the beer brightens
best, if we examine it under the microscope during fermentation, we see,
besides the clusters of yeast-cells, floating amorphous particles, which
are larger and more compact than those to which the turbidity of worts
and muddy beers is due, a circumstance which should lead us to suppose
that the oxygen in combination with the wort has the effect of modifying
the nature of the amorphous deposit which is produced during the
fermentation of the wort. During boiling, the hop yields to the wort a
variety of resinous, odorous, and astringent substances, which, for the
most part, are held in solution by the presence of sugar and dextrin. At
the moment when, under the influence of the yeast, which is itself more
or less oxidized, the sugar becomes transformed into alcohol and
carbonic acid, a portion of the bitter and resinous matters of the hop
becomes insoluble and remains in a state of suspension in the liquid. It
is very probable that at this point it is when the combined oxygen
assumes its function of modifying the physical structure of these
insoluble particles, agglomerating them, so that they become more easily
deposited.[179]
Moreover, oxidation tends to form a special precipitate in the wort,
which precipitate contributes towards the collection and deposition of
the very fine particles suspended in the wort, by a mechanical action,
similar to that which we notice in fining operations. On the coolers an
effect of this kind is produced. The wort in the copper contains
insoluble matters which pass on to the coolers. Very bright when
boiling, it grows turbid as it cools, and then contains two kinds of
insoluble substances: 1. Substances insoluble alike in the hot and cold
liquid, some of which even, as we have just seen, are formed under the
influence of heat and air: all these substances precipitating rapidly to
the bottom of the vessels. 2. Very fine particles insoluble in the cold,
but soluble in the hot liquid, appearing as the wort cools down, and
giving it a milky appearance. If the air does not come into play they
remain in suspension for an indefinite time, so to say. Wort taken
boiling from the copper and cooled down, therefore, forms a considerable
deposit at the bottom of the bottles. Now, if we put this wort into
bottles without filling them, putting into some only the milky wort from
above the deposit, and into others the same wort along with some of the
deposit, then raise it to 100° C. (212° F.), and before it has time to
cool down shake it up with air a good many times, it will be readily
seen that the wort in the bottles containing the deposit will brighten
more rapidly and satisfactorily than those in the bottles without the
deposit. The deposits which are insoluble in the copper have, therefore,
an influence on the clarification. We must add, however, that this
influence cannot be compared with that of direct oxidation.
The “turning out” of the wort and its stay upon the coolers to a certain
extent exhibit the different conditions which take part in its
clarification, inasmuch as the wort charged with its insoluble matters
is run off very hot, and with more or less violence against the external
air.
§ VI.—Application of the Principles of the New Process of Brewing with
the Use of Limited Quantities of Air.
We have now an idea of the quantities of oxygen which occur, free or
combined, in the actual processes of manufacture. We know, moreover,
that an excess of air may be injurious, especially to the aroma of the
beer, and to that quality which consumers prize so highly, which goes by
the name of _bouche_. It must, therefore, be important to ascertain
whether in existing processes the proportion of active oxygen may not be
excessive.
The best practical means of determining this would consist in comparing
the products of different processes with progressively increasing access
of air, starting from none at all, as in the case of cooling in the
presence of an atmosphere of carbonic acid gas. The following
arrangement (Fig. 85) permits us to realize these conditions:—
[Illustration: Fig. 85.]
The wort brought to a temperature between 75° and 80° C. (167° and 176°
F.) in the double-bottomed vessel C, passes by the tube _a b_ into a
refrigerator, such as Baudelot’s, for example, but acting in an inverse
manner to the ordinary mode of using Baudelot’s; that is to say, the
wort is made to circulate inside the tubes, whilst the cold water plays
on the outside.[180] The wort when cooled, its temperature being
indicated by a thermometer _c_, passes down by the tube _c_DD to fill
the fermenting vessel A. This vessel is made of tinned iron, or, better
still, tinned copper, and has a cover provided with a man-hole and
eye-hole; _m n_ one of the tubes for the circulation of air during
fermentation; its connecting-tube is not represented, it would be behind
the vessel.
At the point _d_ there is a pipe for admission of pure air; this is
represented on a larger scale at T. The wort, as it runs through the
large tube, carries with it air from outside, and this air is calcined
on its way in by means of a flame which plays on the copper tube through
which it passes. This arrangement supplies a third or more of the total
quantity of oxygen that the wort is capable of acquiring by solution at
the temperature at which we work.
F represents the arrangement of the reversed funnel in which the tube _m
n_ terminates. Its mouth is closed with cotton-wool held in place
between two pieces of wire gauze, for the purpose of purifying the air
that enters by it into the fermenting vessel during fermentation.
_v_ is an entrance tap for steam, by means of which the vessel and
refrigerator are cleansed from all extraneous germs before each
fermentation, and before the wort passes into the refrigerator.
When the fermenting vessel A is at work, we may start a fermentation in
a second vessel in the following manner: opening a small tap situated at
about a third of the height of the vessel, we pass a few litres of the
fermenting beer into a can of tinned copper, previously purified by a
current of steam, and filled with pure air. This can is then emptied
into the fresh vessel, an operation of no difficulty, since we have
merely to connect the tap of the can with the small tap of the vessel,
and lastly, the vessel is filled with wort, which then mixes with the
fermenting liquid. These various manipulations, it is evident, are
performed under conditions of complete purity, without the slightest
contact of the liquids either with the exterior air or with utensils
contaminated by disturbing germs.[181]
It is seldom that an industry adopts at once in their entirety new
practices which would necessitate a re-arrangement of plant, and the
process of which we are speaking would require such re-arrangement, as
far as the fermenting vessels and the method of cooling the wort are
concerned. The new process would, however, be of great value if once
introduced, simply for the manufacture of pure ferment and pure wort, or
even for that of pure ferment alone. In other words, we might retain the
ordinary methods employed in low fermentation, use the same method of
cooling or the new one, the same fermenting vessels, and the process of
fermentation at low temperatures; the yeast, however, would be prepared
in a state of purity in the closed vessel which we have described,
collected in those vessels, aerated, and then employed after the
old-established custom; better still, the pitching might be performed
with beer in the act of undergoing pure fermentation.
Above the fermenting-stage there might be arranged a room for the
vessels used in the new process, from which the pure beer could be run
for pitching purposes into the large tuns in the brewery below. It is
true that beer prepared in this manner would not be perfectly pure, but
from the results which have been obtained by working on this system,
there is no doubt that it would possess keeping qualities far superior
to those of beer made with ordinary yeast, even supposing that beer to
have been treated with every possible precaution, and to be as pure as
any produced in the best regulated breweries.
In the month of September, 1874, we conducted an experiment at
Tantonville, in a closed vessel capable of holding 6 hectolitres (132
gallons). The deposit of yeast served to pitch an open vessel, the wort
of which had, moreover, been cooled under conditions of purity. The
cooling had been effected by means of the Baudelot refrigerator,
represented in Fig. 85, the wort in the closed vessel having been
similarly treated. For shortness sake, we may designate the closed
vessel and its beer by the letter K, and use the letter M for the open
vessel and its beer, and T for the corresponding beer of the brewery.
The vessel K was pitched on September 4th, and racked on September 17th,
the beer then showing a density of 5·5° Balling.
The beers K and M were sent to Paris at the same time as some barrels of
the beer T, brewed by the ordinary process; and samples of these
different beers, which arrived on October 22nd, were procured from five
different cafés for purposes of examination.
The beer M did not suffer by comparison with the beer T. The similarity
between the flavours of these two was so close as to puzzle even
experienced judges. In both cases the beer was brilliantly clear. In two
cafés the beer M was even preferred to T, being considered softer on the
palate (_moelleuse_) and of more decided character (_corsée_) than T, a
circumstance which may be explained by the fact that its wort had been
less aerated.
The beer K, although very clear and bright, was considered inferior to
M, but the sole reason of this was that at the date when it was
tasted—November 3rd—it did not froth. As we have already remarked, a
peculiarity of the beers made in closed vessels is that their secondary
fermentation takes a longer time to develop. The yeast held in
suspension in the beer, at the moment when it is drawn off, is, in the
case of all beers, the yeast of a supplementary fermentation, if we may
use that expression. In the ordinary process of brewing, this yeast, in
consequence of the greater aeration of the wort at the commencement of
fermentation, is more active, or, rather, more ready to revive and
multiply than is that which develops in closed vessels. If the barrels
of the K beer had been tapped on the 12th or 15th of November, instead
of on the 3rd, it is probable that they would have contained as much
carbonic acid gas as the beer M contained at the earlier date. This
delay in the resumption of fermentation, which characterizes beer made
in closed vessels, is an advantage, inasmuch as it facilitates the
transmission of the beer to long distances, besides giving us the
smallest deposits of yeast in cask or bottle, as we have already pointed
out.
In comparing the keeping qualities of the beer M and the beer T
(the latter being the brewery beer), we made the following
observations:—[182]
On November 25th we began to detect in the brewery beer an unsound
flavour; a large deposit, too, had formed; the beer had lost its
brilliancy, and frothed enormously. The deposit swarmed with diseased
ferments, especially those represented in Nos. 1 and 7 of Plate I. The
beer M, on the contrary, was in brilliant condition, with an
insignificant deposit, and an ordinary froth, if anything, rather small,
and beautifully bright.
On December 3rd the beer M was still good, very clear, and in excellent
preservation; it was considered by professional brewers as remarkably
sound.
December 22nd, the same beer M was still very bright and good.
January 20th, the beer was still bright; for the first time, however, we
detected in the deposit in the bottles, which was still small, the
filaments of turned beer. This unsoundness was in its earliest stage.
Now, comparing the relative unsoundness of the two beers, we see that M
kept at least two months longer than the corresponding brewery beer.
This example shows us that as far as the keeping powers and the quality
of beer are concerned, the existing process would gain considerably by
the employment of pure wort and pure ferment; and, indeed, it seems
likely that the new process may be introduced into breweries with this
object in view.
In the course of the summer of 1875 we made the following observations
on the keeping qualities of a beer brewed on the new system, all the
details of which had been rigorously carried out. The beer brewed at
Tantonville during the months of June and July, at a temperature of 13°
C. (55·4° F.), in 50-litre and 80-litre casks (11 and 18-gallon), had
been sent by slow trains to Arbois (Jura), where we were staying for a
time. The temperature of the wine cellars in which these barrels were
stored was, on June 1st, 12·5° C. (54·5° F.); this rose gradually until
September 1st, when it attained 18° C. (64·4° F.). In this cellar the
brewery beer, brewed in the ordinary way, underwent change in the course
of fifteen days or three weeks, whilst the beer brewed on the new system
remained sound for several months. It is true that some of the barrels
lost their frothiness, and that the beer in them underwent a peculiar
vinous change, but these effects in no way depend on the conditions
peculiar to the new process.
Comparing the beers K, M, T, of which we have been speaking, we see
that, however useful the aeration and oxidation of the wort may be in
quickening fermentation and facilitating clarification, yet it is by no
means indispensable to the success of our operations that we should
introduce into our worts large quantities of oxygen, whether by solution
or combination. Beyond a certain limit—a limit which is undoubtedly
overstepped in the existing process—oxygen is injurious to the palate
characteristics and aroma of beer.
These comparisons have proved to us that the new process can be applied
to wort aerated to the third of its saturate-capacity for oxygen, and
pitched with a good “low” yeast, taken from the fermentation of a wort
aerated in the same way, and that the beers thus obtained not only
possess vastly superior keeping properties, but are equal in quality and
superior in palate-fulness to beers brewed with the same wort on the
existing system. We should be perfectly justified in forming this
conclusion as to the _strength_[183] of the beer furnished by the new
process, even if on tasting it we found that the new beer M was merely
equal in strength to Tourtel’s beer brewed in the ordinary manner, since
the wort in the new process, other conditions being the same, is weaker
than the same wort treated in the usual way, from not having undergone
that evaporation on the coolers which concentrates it. If we were to
restore to the concentrated wort of ordinary brewing all the water lost
by it through evaporation, the beer that we should obtain would be
sensibly weakened.[184]
One thing, however, is that we must employ good varieties of “low”
yeast. We have seen how the employment of certain forms of yeast renders
the clarification of beers difficult, as well as extremely slow, and
almost prevents their falling bright at the end of fermentation. These
yeasts, moreover, frequently impart to beer a peculiar yeast-bitten
flavour, which does not disappear even after a prolonged stay in cask.
Even repeated growth of these yeasts, whether in closed or in open
vessels, and no matter what quantity of air we may supply them with
before fermentation, seems to have no effect in changing their
character. The only thing we can do with these varieties of yeast is to
get rid of them with all speed, and to replace them with others.
Notwithstanding the comparative success that has attended various trials
of the new process on the commercial scale, that process has not yet
been practically adopted: and here we must bear in mind that we have not
to deal with any casual invention or mechanical improvement that could
be introduced all at once into the working of a brewery; we are dealing
with operations of considerable delicacy, which necessitate the adoption
of a special plant to carry them out. Under such conditions time and
labour are required to effect a change in the established processes of a
great industry. This, however, cannot diminish the confidence that we
have in the future of our process, and it is our hope that the same
confidence will be shared in by all those who may give this work an
attentive perusal.
Footnote 162:
M. Galland, a brewer in Maxéville, near Nancy, published with his
name, in November, 1875, a pamphlet, which was reproduced in the
brewing journals of that date, bearing the title, _It is said, “the
air being impure, let us exclude it;” I say, “The air being impure,
let us purify it.”_ These two aphorisms, together or apart, constitute
the essential novelty of my researches on beer, and M. Galland is
mistaken in attempting to appropriate the merit of the second
alternative (see my note in the _Comptes rendus_ of the 17th November,
1873, and the text of the letters-patent obtained 13th March of that
year). M. Galland has devised some arrangements for putting the latter
of these two schemes into practice; but it is possible, of course, to
effect this in a variety of ways. M. Velten, a brewer in Marseilles,
had already accomplished this in his efforts to carry out practically
the procedure advocated in the present work.
Footnote 163:
[Non-technically, stirred about.—ED.]
Footnote 164:
As stated in the paragraph on aërobian ferments, in Chapter V., “low”
yeasts, to be preserved in their state of “lowness,” must be submitted
to often-repeated growths—every fifteen days in winter and every ten
days in summer, that is to say, they must be grown afresh after each
of these intervals. If this is done, there will be no reason to
apprehend the formation of aërobian ferments, which, as we have stated
before, may embarrass us by transforming our “low” yeasts into “high”
yeasts.
Footnote 165:
It has been observed by brewers that, sometimes, without any apparent
cause, a yeast suddenly becomes inactive and fermentation ceases.
Accidents of this kind may probably be explained in the same manner as
the facts of which we are speaking. If a wort has not been aerated, or
if it has been deprived of oxygen by a commencing development of
microscopic organisms, the yeast formed in it will be very inferior,
and the fermentation may stop at its commencement or soon afterwards.
In such a case, an aeration of the yeast and wort would be the best
remedy.
Footnote 166:
PASTEUR, _Comptes rendus de l’Académie des Sciences_, vol. lii. p.
1260, and _Études sur le Vin_, 2nd Edition, p. 277.
Footnote 167:
We may here remark that the system of gutters in the above apparatus
is much simpler than that described in connection with Figs. 76 and
77. The water which falls on the cover is carried off, when the gutter
is full, by a circle of grooves, inclined so that the streams running
from them meet and form more readily a sheet of water, which flows
over the exterior surface of the cylindrical vessel.
Footnote 168:
[It will be well for the reader to bear in mind, that the word
“strength,” used by Pasteur many times in this chapter, has a
different meaning to that which attaches to it in the minds of English
brewers, who in nearly every case use it in reference to _original
gravity_, while the author employs it, in this chapter, at any rate,
to denote the _palate characteristic of strength_, in other words
_palate-fulness_. For this reason we have thought it best in many
cases to actually substitute the term “palate-fulness,” or “body,” for
the literal translation of the French word “force.”—F. F.]
Footnote 169:
[As some confusion has existed in the nomenclature of these salts, it
may be as well to offer some explanation.
The salt here used for absorbing oxygen was discovered by
Schützenberger, and named by him _hydrosulphite of soda_. It no longer
now goes by that name, being called _hyposulphite of soda_, NaHSO_{2}.
The salts formerly known as _hyposulphites_ are now called
_thiosulphates_, as Na_{2}S_{2}O_{3}.
Thus to put them together we have:—
Hyposulphite (Hydrosulphite) NaHSO_{2}
Bisulphite NaHSO_{3}
Thiosulphate (Hyposulphite) Na_{2}S_{2}O_{3}
The thiosulphates were formerly regarded as containing the elements of
water in their composition, thus:—Na_{2}H_{2}S_{2}O_{4}, which being
halved would give NaHSO_{2}, isomeric with hyposulphite, as Pasteur
says. It is further to be observed that Pasteur uses the old notation,
in which the number of atoms of sulphur and oxygen are the double of
what they are in the new.—D. C. R.]
Footnote 170:
SCHÜTZENBERGER, _Comptes rendus de l’Académie des Sciences_, vol.
lxxv., p. 880.
Footnote 171:
M. Schützenberger applies the term _saturated_ to a solution of
hydrosulphite prepared thus, or very nearly so; a current of
sulphurous acid is passed through a solution of commercial bisulphite
of soda, to excess; 100 c.c. (3-½ fl. oz.) of this solution and 30
grammes (46 grains) of zinc filings are put into a small flask, so as
to completely fill it; the bottle is corked up and the mixture is
shaken briskly for about a quarter of an hour. Lastly, the contents of
this flask are poured into a large 2-litre flask, with water and
containing milk of lime, prepared by mixing 100 grammes (3·2 troy oz.)
of quicklime in the water just before it is used. The whole is shaken
briskly for some minutes and then left to settle. The supernatant
liquid soon becomes bright. This is the hydrosulphite; but in this
state it is too concentrated; and should be syphoned into another
2-litre flask half full of water. In the alkaline condition this salt
absorbs gaseous oxygen much less rapidly than in the acid, so that the
liquids will retain their strength much longer, if they are kept in
well-corked bottles.
Footnote 172:
The numbers _n_ and _n´´_ will vary as the wort, or liquid which we
have to test, is perfectly neutral or otherwise. Should it be acid
_n´´ n_, should it be alkaline _n n´´_. This would be a very exact
method of estimating the acidity or alkalinity of any coloured liquid.
Footnote 173:
[The Balling saccharometer being almost unknown in England, we may
explain that its indications are for percentages of sugar in
saccharine solutions, or of extract in worts; 17·9° Balling,
therefore, means 17·9 per cent. of sugar or extract in the respective
liquids.—F. F.]
Footnote 174:
Experiments made, at our request, by MM. Calmettes and Grenet, at
Tantonville; in Tourtel’s brewery.
Footnote 175:
See foot-note, page 367.
Footnote 176:
[For non-technical readers we may explain the expressions “gathered,”
here used, and “turning out,” used on page 365. “Turning out”
describes the operation of emptying the _copper_ contents into the
_hop-back_, or the _hop-back_ contents on to the _coolers_.
“Gathering” refers to the time when the worts are finally intermixed
and _weighed_, prior to the commencement of vinous fermentation.—F.
F.]
Footnote 177:
We know also from the direct experiments of M. Schützenberger,
performed on aerated water with which yeast had been mixed, that yeast
causes all the oxygen in solution to disappear very quickly, so that
hydrosulphite gives no evidence of a trace. (See SCHÜTZENBERGER,
_Revue scientifique_, vol. iii. (2), April, 1874).
Footnote 178:
[The bottling needle (_foret â aiguille_) is a contrivance for
permitting a cork to be driven into a bottle completely filled with
liquid, without bursting the bottle. It consists of a
slightly-tapering iron pin about 1/8th inch in diameter and 2 inches
in length, somewhat flattened, and slightly curved throughout its
entire length, with a groove running down one side from end to end,
the pin being jointed with a ring, like a common ring cork-screw. In
using it the pin is driven into the bottle alongside the cork, thus
allowing the excess of liquid to escape as the cork advances. When the
cork is completely home, the needle is withdrawn, and the elasticity
of the cork enables it to fill up the space left, so that we have the
bottle corked air-tight, and no air left between the cork and
liquid.—D. C. R.]
Footnote 179:
We have remarked in our observations on No. 6 of Plate I. (p. 6) that
amongst the amorphous granular deposits of wort and beer we often find
minute balls of resinous and colouring matter, perfectly spherical and
very dense, which if the liquids be shaken up will render them very
turbid, but which readily and rapidly deposit again, without remaining
in suspension in the least. Such then is the form in which the
deposits of wort in course of fermentation are precipitated, when the
wort has been freely exposed to oxygen. One day in the laboratory we
were desirous of starting a fermentation in a vessel capable of
holding 12 hectolitres (264 gallons). But as we only had at our
disposal a copper capable of holding 2-½ hectolitres, we procured the
wort from a neighbouring brewery in two barrels of 6 hectolitres each.
This wort we re-heated, in portions, in our 2-½ hectolitre copper, a
treatment which had the effect of oxidizing the wort more than it
would have been in the brewery. In this case the beer fell remarkably
bright, and the cells of yeast were accompanied by the deposit of
minute agglomerations sketched in Plate I., No. 6. We have repeated
this experiment on a smaller scale and have obtained the same result.
Footnote 180:
It is evident that this arrangement may be modified in many ways. Any
of the ordinary worms, or, generally speaking, any of the more modern
refrigerators invented during the last few years, may be adopted. The
only point that is of importance is the preservation of the purity of
the wort during cooling.
The Baudelot refrigerator is extensively adopted in France; for this
reason we used it in our experiments at Tantonville. We might equally
well, by enclosing the worm in a casing of sheet iron or tinned
copper, pass our wort over the exterior of the tubes, the cold water
passing through them. The wort would cool quicker in this way than
with the arrangement described in the text, and if we arrange to admit
only pure air into the case, always under conditions of purity. The
aeration, moreover, could be made as much as we wished.
Footnote 181:
This arrangement limits the proportion of oxygen that may be
introduced into the wort by direct oxidation. But it would be easy to
increase this at will, by causing the wort as it comes from the copper
and the hop-back to pass into a cylinder turning horizontally on its
axis and furnished with blades fixed inside, so as to divide the wort
and bring it better into contact with the air in the cylinder. Instead
of a revolving cylinder we might use a fixed vessel, in which the wort
could be stirred up by some arrangement outside. In either case we
should have to take care that the air was pure when it came into
contact with the wort, but this would be a matter of no difficulty; we
would simply have to make communication with the outer air by means of
a tube filled with cotton wool. Any air that might be in the vessel at
the moment when the wort was introduced would be purified by the high
temperature of the wort coming from the copper. We should, moreover,
gain the great advantage of being able to bring oxygen to bear on our
wort in determinate amounts. From this vessel it would pass on to the
refrigerator. We might again raise the wort oxidized on the coolers to
a temperature of 75° C. (167° F.), to recool it in this manner and
aerate it by means of the pure-air pipe.
Footnote 182:
One of the barrels of the brewery beer was bottled about the end of
October, at the same time that a barrel of M was.
Footnote 183:
Refer foot-note, page 354.
Footnote 184:
The evaporation on the coolers varies according to the arrangements in
different breweries; but in no case is it less than several hundredths
of the total volume. One special advantage of the new process is that
it gives us, _ceteris paribus_, a volume of beer that is 5, 6, or 7
per cent. greater than that which we should obtain by the old process,
without in any way affecting the strength of the beer. It is easy to
ascertain the quantity that evaporates on the coolers, by determining
the quantity of water that must be added to a known volume of wort
coming from the coolers to bring its density back exactly to that of
the original wort, both being calculated to the same temperature.
Bate’s English saccharometer, which shows differences of nearly
1/1000th in density, may be employed with advantage in this
determination.
APPENDIX.
Whilst this work was passing through the press there appeared two small
works on the subject of the generation of inferior organisms.
One of them was by M. Fremy. The author’s object seems to have been
merely to give an account, under a new form, of the part which he took
in the discussion on the origin of ferments that was carried on before
the Academy of Sciences in 1871-1872. In the course of that discussion
M. Fremy had announced his intention of publishing an extensive Memoir,
full of facts, bearing on the subject. The perusal of the promised work
gave us much disappointment. Not only were our experiments, and the
conclusions which we drew from them, given there, for the most part in a
manner which we could not possibly accept, but, moreover, M. Fremy had
confined himself to deducing, by the help of his favourite hypothesis, a
series of _à priori_ opinions based on half-finished experiments, not
one of which, in our opinion, had been brought to the state of
demonstration. To tell the truth, his work was the romance of
hemi-organism, just as M. Pouchet’s work of an earlier date was the
romance of heterogenesis. And yet, what could be clearer than the
subject under discussion? We maintain, adducing incontestable
experimental evidence in support of our theory, that living, organized
ferments spring only from similar organisms likewise endowed with life;
and that the germs of these ferments exist in a state of suspension in
the air, or on the exterior surface of objects. M. Fremy asserts that
these ferments are formed by the force of hemi-organism acting on
albuminous substances, in contact with air. We may put the matter more
precisely by two examples:—
Wine is produced by a ferment, that is to say, by minute, vegetative
cells which multiply by budding. According to us, the germs of these
cells abound in autumn on the surface of grapes and the woody parts of
their bunches; and the proofs which we have given of this fact are as
clear as any evidence can be. According to M. Fremy, the cells of
ferment are produced by spontaneous generation, that is to say, by the
transformation of nitrogenous substances contained in the juice of the
grape, as soon as that juice is brought into contact with air.
Again, blood flows from a vein; it putrefies, and in a very short time
swarms with bacteria or vibrios. According to us the germs of these
bacteria and vibrios have been introduced by particles of dust floating
in the air or derived from the surface of objects, possibly the body of
the wounded animal, or the vessels employed, or a variety of other
objects. M. Fremy, on the other hand, asserts that these bacteria or
vibrios are produced spontaneously, because the albumen, and the fibrin
of the blood themselves possess a semi-organization, which causes them,
when in contact with air, to change spontaneously into these
marvellously active minute beings.
Has M. Fremy given any proof of the truth of his theory? By no manner of
means; he confines himself to asserting that things are as he says they
are. He is constantly speaking of hemi-organism and its effects, but we
do not find his affirmations supported by a single experimental proof.
There is, nevertheless, a very simple means of testing the truth of the
theory of hemi-organism; and on this point M. Fremy and ourselves are
quite at one. This means consists in taking a quantity of grape juice,
blood, wine, &c., from the very interior of the organs which contain
those liquids, with the necessary precautions to avoid contact with the
particles of dust in suspension in the air or spread over objects.
According to the hypothesis of M. Fremy, these liquids must of necessity
ferment in the presence of pure air. According to us, the very opposite
of this must be the case. Here, then, is a crucial experiment of the
most decisive kind for determining the merits of the rival theories, a
criterion, moreover, which M. Fremy perfectly admits. In 1863, and again
in 1872, we published the earliest experiments that were made in
accordance with this decisive method. The result was as follows:—The
grape juice did not ferment in vessels full of air, air deprived of its
particles of dust—that is to say, it did not produce any of the ferments
of wine; the blood did not putrefy—that is to say, it yielded neither
bacteria nor vibrios; urine did not become ammoniacal—that is to say, it
did not give rise to any organism; in a word the origin of life
manifested itself in no single instance.
In the presence of arguments so irresistible as these, M. Fremy,
throughout the 250 pages of his work, continues to repeat that these
results, which, he admits, seem subversive of his theory, are,
nevertheless, explicable by the circumstance that the air in our
vessels, although pure at first, underwent a sudden chemical change when
it came in contact with the blood, or urine, or grape juice; that the
oxygen became converted into carbonic acid gas, and that, in
consequence, hemi-organism could no longer exercise its force. We are
astonished at this assertion, for M. Fremy must be aware that, since
1863, we have given analyses of the air in our vessels after they had
remained sterile for several days—for ten, twenty, thirty, or forty
days—at the highest atmospheric temperatures, and that oxygen was still
present, often even in proportions almost identical with those to be
found in atmospheric air.[185] Why has M. Fremy made no allusion to
these analyses? This was the chief, the essential point in question.
Besides, if M. Fremy had wished to test the truth of his explanation,
there was a very simple means of restoring the purity of the air in
contact with the liquids open to him; he might have passed through his
vessels a slow and continuous current of pure air, day and night. We
have done this a hundred times, and we have always found that the
sterility of the putrescible or fermentable liquids remained unaffected.
The hemi-organism hypothesis is, therefore, absolutely untenable, and we
have no doubt that our learned friend will eventually declare as much
before the Academy, since he has more than once publicly expressed his
readiness to do so as soon as our demonstrations appear convincing to
him. How can he resist the evidence of such facts and proofs?
Persistence in such a course can benefit nobody, but it may depreciate
the dignity of science in general esteem. It would gratify us extremely
to find the rigorous exactness of our studies on this subject
acknowledged by M. Fremy, and regarded by that gentleman with the same
favour bestowed upon it everywhere abroad. It may be doubted if there
exists at the present day a single person beyond the Rhine who believes
in the correctness of Liebig’s theory, of which M. Fremy’s hemi-organism
is merely a variation. If M. Fremy still hesitates to accept our
demonstrations, the observations of Mr. Tyndall may effect his
conversion.
The other publication to which we alluded was the work of the celebrated
English physicist, John Tyndall. It was read before the Royal Society of
London, at a meeting held on January 13, 1876.
The following letter explains how the illustrious successor of Faraday
at the Royal Institution came to undertake these researches:—
“London, February 16, 1876.
“Dear Mr. Pasteur,—
“In the course of the last few years a number of works bearing such
titles as ‘The Beginnings of Life’; ‘Evolution and the Origin of
Life,’ &c., have been published in England by a young physician, Dr.
Bastian. The same author has also published a considerable number of
articles in different reviews and journals. The very circumstantial
manner in which he describes his experiments, and the tone of
assurance with which he advances his conclusions, have produced an
immense impression on the English as well as the American public.
But what is more serious still, from a practical point of view, is
the influence that these writings have exercised on the medical
world. He has attacked your works with great vigour, and, although
he has made but slight impression on those who know them thoroughly,
yet he has succeeded in producing a very great and, I may add, a
very pernicious one on others.
“The state of confusion and uncertainty had come to be so great
that, about six months ago, I thought that I should be rendering a
service to science, and at the same time performing an act of
justice to yourself, in submitting the question to a fresh
investigation. Putting into execution an idea which I had
entertained for some six years, the details of which were set forth
in an article in the _British Medical Journal_, which I had the
pleasure of sending you, I have gone over a great deal of the ground
on which Dr. Bastian had taken his stand, and, I believe, refuted
many of the errors by which the public had been misled.
“The change which has taken place since then in the tone of the
English medical journals is quite remarkable, and I am inclined to
think that the general confidence of the public in the exactness of
Dr. Bastian’s experiments has been considerably shaken.
“In taking up these researches again, I have had occasion to refresh
my memory by another perusal of your works; they have revived in me
all the admiration which I experienced when I first read them. It is
my intention now to pursue these researches until I have dissipated
any doubts that may be entertained in respect to the unassailable
exactness of your conclusions.
“For the first time in the history of science, we are justified in
cherishing confidently the hope that, as far as epidemic diseases
are concerned, medicine will soon be delivered from empiricism, and
placed on a real scientific basis; when that great day shall come,
humanity will, in my opinion, recognise the fact that the greatest
part of its gratitude will be due to you.
“Believe me, ever very faithfully yours,
“JOHN TYNDALL.”
We need scarcely say that we read this letter with the liveliest
gratification, and were delighted to learn that our studies had received
the support of one renowned in the scientific world alike for the
rigorous accuracy of his experiments as for the lucid and picturesque
clearness of all his writings. The reward as well as the ambition of the
man of science consists in earning the approbation of his
fellow-workers, or that of those whom he esteems as masters.
Mr. Tyndall has observed this remarkable fact, that in a box, the sides
of which are coated with glycerine, and the dimensions of which may be
variable and of considerable size, all the particles of dust floating in
the air inside fall and adhere to the glycerine in the course of a few
days. The air in the case is then as pure as that in our double-necked
flasks. Moreover, a transmitted ray of light will tell us the moment
when this purity is obtained. Mr. Tyndall has proved, in fact, that to
an eye rendered sensitive by remaining in darkness for a little, the
course of the ray is visible as long as there are any floating particles
of dust capable of reflecting or diffusing light, and that, on the other
hand, it becomes quite obscure and invisible to the same eye as soon as
the air has deposited all its solid particles. When it has done this,
which it will do very quickly in two or three days, if we employ one of
the boxes used by Mr. Tyndall—it has been proved that any organic
infusions whatever may be preserved in the case without undergoing the
least putrefactive change, and without producing bacteria.
On the other hand, bacteria will swarm in similar infusions, after an
interval of from two to four days, if the vessels which contain them are
exposed to the air by which the cases are surrounded. Mr. Tyndall can
drop into his boxes, at any time he wishes, some blood from a vein or an
artery of an animal, and show conclusively that such blood will not,
under these circumstances, undergo any putrefactive change.
Mr. Tyndall concludes his work with a consideration of the probable
application of the results given in his paper to the etiology of
contagious diseases. We share his views on this subject entirely, and we
are obliged to him for having recalled to mind the following statement
from our _Studies on the Silkworm Disease_:—“Man has it in his power to
cause parasitic diseases to disappear off the surface of the globe, if,
as we firmly believe, the doctrine of spontaneous generation is a
chimera.”
THE END.
Footnote 185:
See _Comptes rendus_, vol. lxi., p. 734, 1863.
INDEX.
A
Absorption of gases by air-free liquids, 292
oxygen by blood, 50;
by urine, 50
from solutions by _bacteria_, 295
Acidity, natural, of wine a preservative, 2, and footnote
of beer heated, 20
action on ferments, 35
Acetate of lime from fermentation of tartrate, 288
Acid, sulphuric, facilitating filtration, 250
Acid, carbonic, _v._ carbonic acid
Adaptability of liquids to certain growths, 36, 73, 85
(supposed) of vibrios to aërobian or anaërobian conditions, 309, 310
Aeration, reviving influence of, 138
adoption by brewers of, 253
tardy, of wort in deep vessels, 348
on “coolers,” its importance, 348, 349
Aeration-conditions in ordinary brewing process, 350, 351, 364, 365
Aeration of wort, apparatus for regulating, 352
Aeration, influence on clarification of worts, 381
experiments on its influence on growth, 107, 130
Aërobian, definition, 116
ferment, growth of, 208, 209
ferments, general characteristics, 210;
origin of, 210 (footnote);
cultivation of, 211;
aspects of, 212-217;
distinguishing features of, 218
life in ferments overlooked, 260
“Age,” as applied to a ferment, 169
Age of cells, 246
Aged aspect of exhausted cells, 133, 147
Air, influence on ferment-life, 242
renewal of, in brewers’ yeast, 246, 247
mode of expulsion from growing media, 285
unnecessary to life of _vibrios_, 292
injurious to life of _vibrios_, 304
Air, compressed, and ferment-life, 324
composition unaffected by contact with blood, &c., 398
Albumen-transformation theory of fermentation, 273
Albuminous liquids, growth of yeast in, 265
Alcohol, percentage is heated beer, 20
Alcoholic ferment, minute species of, 71
Alcohol, detection in minute quantity, 78, 79 (footnote)
produced by _penicillium_, 99, and following pages
by _aspergillus glaucus_, 101, and following pages
by _mycoderma vini_, 111, 113
explanation of, 114
Alcoholic fermentation, general explanation of, 114, 115
Alcohol, proportion of, to mucor forming it, 134, and following pages
Alcohol produced by moulds, 258 (footnote)
production of, within fruits, 267
Alcoholic fermentation, restricted meaning, 275 (footnote)
necessary relation with yeast-cells, 275
_Altenaria tenuis_, 157
Ammonia, a test for vegetable organisms (Robin), 312
Ammoniacal urine, 45, 46
Anaërobian, definition, 116
growth of yeast, 239, and following pages
precautions to be observed in, 248
life of fruit-cells, 272
growth of _vibrios_, 302
Animal or vegetable nature of organisms, 312, and following pages
Anti-ferments, 45
Apparatus for sterilizing liquids, 27
for producing pure beer, 340, &c.
for pure pitching, 344
for pure aeration, 352
for cooling beer with regulated supply of pure air, 388, 389
Appert’s experiment, 62
Aroma of beer destroyed by excess of air, 353
Asbestos, useful plug, 27, and footnote, 30
Ascospores of yeast, 150 (footnote)
Aspect of yeast variable, 37
_Aspergillus glaucus_, functioning as ferment, 101, and following pages
different aspects of, 105
Atmospheric germs, 6, 26, 38
variety of, 39, 76, 87 (footnote)
_Autonomy_ of organisms, 84 (footnote)
B
Bacteria, 35, 36;
medium for growth of, 294;
absorption of air from solutions by, 295
Bacteria and butyric vibrios, how related, 296
influence of oxygen upon, 305
Bail mentioned, 92, 93, 127
Balling saccharometer explained, 363 (footnote)
Barley-wine, 1 (footnote), 230
Barley decoctions, experiments on development of ferments in, (Fremy)
273 (footnote)
Bary, De, mentioned, 92;
on relations of yeast to other organisms, 180, 181
Bastian’s experiments, 403
Baudelot refrigerator, 387 (footnote)
Bavarian beer, 10
Béchamp’s _microzyma_ theory, 121
influence of air on fermentation, 178 (footnote)
Beer, definition, 1;
difference between it and wine, 1
changeable nature of: effects upon brewing purposes, 2, 3
two kinds only, “high” and “low:” difference, 7
samples of bottled, examined, 222
general precautions for pure manufacture of, 338
improved apparatus for commercial production, 340, and following
pages
Beet root preservation in pits, 269 (footnote)
Berkeley mentioned, 92
Bellamy’s researches on fermentation in fruits, 270
Berard on fermentation of fruits, 270, 271
Berthelot’s mode of isolating inverting constituent of yeast, 322
(footnote)
Bert, action of compressed air on ferments, 324
Birds, experiment upon, described, 309
Bistournage, 43 (footnote)
Bisulphite of lime used by bottlers, 15
Blood, study of sterilized, 49, 50
Blood-crystals, 50 (footnote)
Boiling sterilizes liquids, 34
Bottling needle, 372 (footnote)
Bottled beer, treatment of, 16
_Bouche_ influenced by presence of oxygen, 387
Bouchardat, 323
Brefeld, strictures on Pasteur’s theory criticised, 280
convinced of truth of Pasteur’s theory, 315, 316
Breweries, statistics of, 10
Brewing, change in processes of, 7
practices largely empirical, 222
Brewing processes under conditions of purity, 390
Budding, rate of, experiment on, 145
process of, 146
Buffon’s hypothesis mentioned, 121
Bulbs, glass, for study of growths, 156 (footnote)
for vibrios, 298
Bunsen, tables of solubility of oxygen in water, 360
Butyric vibrios in must, 65;
in wort, 70
Butyric acid from fermentation of lactates, 297
not a suitable food for vibrios, why?, 301 (footnote)
Butyric fermentations yield variable products, 308
C
Cagniard Latour, on cause of fermentation, 60
Calmettes, M., 369, 371;
experiments on the curve of cooling of wort, 377, 378
Carbolic acid for purifying yeasts, 232
Carbonate of lime crystals formed in fermentation of lactate, 294
Carbonic acid, influence on preservation and fermentation of fruits,
268
evolution from fermentation of tartrate of lime by vibrios, 287
amount of evolution, 288
mode of collection of, 288
influence on bacteria, 305 (footnote)
Caseous ferment, occurrence, 200;
aspect, 201;
endurance of heat, 203 (footnote);
meaning of title, 202;
origin of in brewers’ high yeast, 203, 204;
origin of in English pale ale, 204, 224;
aërobian form of, 215
Cells, power of endurance, 134
aspect of dead, 139 (footnote)
Cells, glass, for study of growths, 155 (footnote)
Cells, probable function in elaborating proteic matter, 335
Cellulose, not soluble in ammonia (Robin), 312
Change of yeast, usual remedy for disease, 22
Chauveau on castration, 43
Circumstances modifying nature of germs present in atmosphere, 73, 87
(footnote)
_Cladosporium_, 55 (footnote)
Clarification of liquids by fungi, 66 (footnote)
of wort, 381, and following pages
of a wort and its beer not always correlated, 382, 383
Cohn’s medium for growth of vibrios, 294 (footnote)
Colour darkened by oxidation in pure liquids, 57
Coloration of vibrio-fermented liquors, 291
Colpoda, 39, 40
Composition of medium, influence on life, 296
Conidia, definition, 137
Conditions affecting the ferment character of cells, 266
Consumption of beer in France, statistics, 17 (footnote)
Contagion and ferments, 41, and following pages
Continuity, non-, of germs in air, 62
Continuous vital activity of cells, 278
Contact-action, theory of, 326
“Coolers,” importance in aeration of wort, 348, 349
influence on worts, 364
Cooling of wort must be rapid in ordinary brewing, 2
artificial of “low” beers, 12
Cooling of wort in presence of carbonic acid, 342;
difficulties of the process, 346, and following pages
Corpuscles on grapes and stalks, 54
Corpuscles refractive in bodies of vibrios, 300, _v._ also cysts
Correlation of special germs with special fruits, 61
of special ferment and fermentation product, 277
Cotze and Feltz, 43
Crushers for the vintage, 268 (footnote)
Cream of tartar, _v._ tartrate
Cultivation of yeast under conditions of purity, 29-32
of pure penicillium, mode of, 88, and following pages
of aërobian ferments, 211, and following pages
Cysts of vibrios, 306, 307
D
Davainne, on splenic fever, &c., 42
Daughter-cells, 146
Dead cells, aspect of, 139 (footnote)
Declat’s treatment of infectious diseases, 44
_Dematium_, 167;
resemblance to _Saccharomyces pastorianus_, 179, 180, 181, 214
resemblance to “caseous” yeast, 201
Degrees, Balling, _v._ Balling
Deposits, amorphous, of wort, 6, 193, 385, and footnote
Deterioration of beer correlated with presence of foreign organisms,
26, 32
Differential vitality, a means of separating ferments, 226
Difficulty of experiments on growths, 63, 85
Disease-ferments, what they are, why so called, 4
classification and account of, 5, 6
origin of, 6
inactive at low temperatures, 14
often found only in deposits, 24
not everywhere in atmosphere, 31
Disease-germs usually latent, 220
development in bottled beer, 222
Diseases of wort and beer, meaning of, 19
mode of proving the cause of, 19, 20
Diseased beer always result of disease ferments, 26
Distribution of germs limited, 61
Division, fissiparous, of vibrios, 299
Dried yeast, 81
Dryness decreases sensitiveness of moulds to heat, 35
Dumas, distinction between organized and unorganized ferments, 323
Dust, atmospheric, contains disease-germs, 6, 26
on fruits, experiments with, 153, and following pages
when fertile, 157, and following pages
Dutch yeast, 200
Duval, Jules, experiments on transformation of ferments illusory, 37
E
_Efflorescence_ of fermented liquors, 108, 117
Egg-albumen, experiments on, 51
Egypt, beer first brewed in, 17
Empiricism in ordinary brewing, 222
Energy stored by cells, 133, 134
Endogenous sporulation of yeast, 150 (footnote), 172
English beers all “high,” 7
temperatures and yeast employed, 8 (footnote)
breweries, usages of, 8 (footnote), 14
Errors, causes of, _v._ experimental errors
Equations of fermentations variable, 276, 277
Examination of deposits, mode of, 21 (footnote)
Exhaustion, definition of, 171 (footnote)
Exhausted vibrios, 290
Experimental errors, 63, 85, 92
avoided by use of double-necked flasks, 120
Experiments, exactness of Pasteur’s, 95 (footnote)
to prove connection between quality of ferment and quality of beer,
26, and following pages
on living fluids, 47, and following pages
comparative, on pure must and must with corpuscles boiled and
unboiled, 54, and following pages
by Gay-Lussac on must, 62, 63
by Pasteur after Gay-Lussac, 64
on distribution of ferments, 65, and following pages
on distribution of fungus-spores, 68
in wide shallow dishes, 69, and following pages
comparative on germs in air, 72, and following pages
with non-fermentative species of _torula_, 78
on spontaneous impregnations, 65, 66, 69, 73, 79, 87 (footnote)
on spontaneous fermentation, 184
on dried yeast, 81, and following pages
on influence of aeration on growths, 107
on aeration and its absence, 130, and following pages
on function of oxygen on ferment-life, 238, and following pages
on the capacity of yeast for oxygen, 255
on influence of carbonic acid on fruits, 268
on growth of vibrios apart from air, 285
on fermentation of lactate of lime apart from air, 292, and following
pages
on influence of air on vibrio-life, 303, 304
on influence of air on bacterium-life, 305
on gradual adaptability of organisms to adverse life-conditions, 309
on influence of air on fermentation, 349
on solubility-coefficients of wort for oxygen, 361-3
of brewers’ worts, 366, and following pages
on combination of oxygen with worts, 371, and following pages
on the rapidity of the combination, 376
on amount of combination, 379
on non-transformation of _mycoderma vini_, 110, and following pages,
113 (footnote)
of _mycoderma aceti_, 124, and following pages
of _mucor racemosus_, 128, and following pages
on non-transformation of yeast into penicillium, 333-335
on cultivating pure _penicillium_, 88, and following pages
on its transformation into yeast, 91
transformation, Trécul’s, details of, 98
with submerged _aspergillus_, 101, and following pages
_penicillium_, 99
in disproof of the _hemi-organism_ theory, 273 (footnote)
on growth of mixed moulds, 112
on purification of mixed ferments, 226, and following pages
on growth of _mucor mucedo_, 140, 141
on proportion between weights of mucor and alcohol formed, 134, and
following pages
on the anaërobian cultivation of yeast, 239, and following pages
on variation of proportion of sugar used to yeast formed, 249
on growth of yeast in sugar solutions, 318, and following pages,
331-333
on dust on fruits, 153, and following pages
on seasonal influences on fertility of dust-germs, 157, and following
pages
on exhaustion of yeast, 169, and following pages
of “high” yeast, 189, 190
on revival of yeast, 207, 208
on cultivation of aërobian ferment, 211, and following pages
on gradual _senescence_ of yeast, 245
on production of a pure beer, 338, and following pages
on clarification of worts and beers, 382, and following pages
comparative, on the qualities of beers brewed by different processes,
391
on rate of budding, 145
Exportation of “high” beers unsatisfactory, 16
F
Ferment, _v._ also yeast
Ferments of disease, _v._ disease-ferments
Ferments, special, 14, 15
Ferments and animal diseases, 41, and following pages
butyric, lactic, alcoholic, 72
moulds functioning as, 100, 101, and following pages, 111, 113, 129,
133
general character of a, 115
of grape, varieties, origin, 150, and following pages
alcoholic, summary of, 196
intermixture of, 224, 225
mode of separation of mixed, 226 and following pages
succession of, in must, 227
exceptional vital processes of, 236, 237
Ferment power in relation to time discussed, 252
character, how related to heat, 270
and fermentation correlated, 277
a chemical substance existing in cells (Traube), 283 (footnote)
of tartrate of lime, 290
Ferments, two classes, distinctive characteristics, 323
Fermentation, rapid, inexpedient, 3
spontaneous, in case of must, 4
“top” and “bottom,” _v._ “high” and “low”
masked by moulds in shallow vessels, 75 (footnote)
by _penicillium_ (Tréoul) 94
by _mycoderma vini_, 111, 113
by _mucor racemosus_, 129, 139
alcoholic, general explanation of, 114, 115
conditions of, in sweetened mineral liquids, 211
without air, 242
with and without air, results compared, 243, 244
a cell-life without air, 259
a general phenomenon, 266, 267
of fruits not truly “alcoholic,” 276
not definable, according to Brefeld, as life without air, 280
of lactate of lime, 294
Fermentative energy, 252
character dependent on conditions, 266
Filamentous tissue (Turpin), 123
Fitz on fermentation, 142
Fissiparous division of vibrios, 299
Flask sterilizing, 27, 29
Flasks with double necks, advantage of, 120
Fluid, Raulin’s, 88 (footnote)
Flavour dependent on ferment species, 230
Foreign organisms correlated with unsound beer, 26, 32
greatly promoted by adaptability of liquids, 36
Formula for solubility-coefficient of any wort for oxygen, 364
Fremy’s statement of _hemi-organism_, 52
answer to Pasteur’s facts, 58
explanation of vintage fermentation, 272
“organic impulse,” 325
latest assertions, 396-399
Fruits, ferment organisms on surface of, 153, and following pages
internal fermentation of, 267, and following pages
yeast cells not present within, 267 (footnote)
influence of carbonic acid gas on preservation of, 268
respiratory processes of, according to Bérard, 270
fermentation within, Lechartier and Bellamy, 270
crushed and uncrushed, fermentation of, 274
Fruit-cells, anaërobian life of, 272
Fungi, wide distribution of spores, 68
absorption of oxygen by, 257
production of alcohol by, 258 (footnote)
Fungoid manner of growth of well-aerated yeast, 251
G
Galland’s claims of priority, 338 (footnote)
Gay-Lussac’s experiments on grape-juice, 59, 60
Gayon’s experiments on egg-albumen, 51
“Gathered,” 367 (footnote)
Generation, theories of, contrasted, 397
Germs of ferments in air, &c., 6, 26, 38
brought by other matters, 38
absent from fruits, when? 58, 59, 157, and following pages
not universally distributed, 61, 63, 181 (footnote)
distribution experiments, 65, and following pages, 87 (footnote)
and their correlated fruits, 61
of disease latent, 220
_Germ_, use of term by Pasteur, 313
Germ theory of disease discussed, 46, 47
Globuline tissue (Turpin), 123
Globulines, punctiform, 121, and following pages
Globules, 275 (footnote)
Glycerine, fermentation of, by vibrios, 306, 307
Gosselin, M., report, 44
and Robin on ammoniacal urine, 45
Gramme, value in grains, 135 (footnote)
Granules in wort, explanation of, 95
Graham’s, Dr., criticisms of Pasteur, 13 (footnote), 196 (footnote)
Graham, Dr., on aspect of bottom yeast, 194 (footnote)
Grape juice, experiments on, 57, 59
Grape-ferments, _v._ ferments
Grapes, do they contain cells of yeast? 267
Greasiness of _mycoderma vini_, 80, and footnote
H
Hallier mentioned, 92
Hard water, influence on aspect of yeast, 194 (footnote)
_Head_ of vibrio, 292
Heating sufficient as preventing deterioration of liquids, 20
influence on beer, 20
Heat, production of, its relation to ferment-power, 270
_Hemi-organism_, chimerical, 53, 162, 399, 273 (footnote)
latest assertions by Fremy on subject of, 396-399
theory of vintage-fermentation, 272, 273
Heterogenesis, facts against, 51
“High” fermentation, meaning of, 8, 9
beers, disadvantages of, 12, 13
ferment, aspect of, 188, 189
characteristics of, summary, 191
ferment (new), occurrence, 198
aspect and characteristics of, 199
aërobian form of, 216
High yeast, aërobian form, aspect of, 214
Hoffmann, H., transformation of ferment, 92, 93
Hop-oil as a beer-antiseptic, 16, and footnote
Hopping influence on growths _quâ_ temperature, 96
Hot countries, absence of breweries in 16
Hydrogen from vibrionic life, 300
occasional absence in butyric fermentations, 308
Hydrosulphite of soda, composition, use in determinations of oxygen,
355, and footnote
preparation of _saturated_ solution, 357 (footnote)
alterability of solutions of, 356
improved method of M. Raulin, 356, and following pages
I
Ice, quantities consumed in “low” breweries, 11
Illusions as to absence of foreign organisms, 36, 85, 92
Impregnations, spontaneous, 65, 66, 69, 73, 79
Impregnation, mode of (_penicillium glaucum_), 86
Impurity of ferments, source of experimental errors, 37
of yeast masked for a time, 220
Increase of yeast disproportionate to sugar used, 237
Infusions, nature of organisms in, 39
Infusoria, 35
Insoluble substances in wort, 386
Inverting constituent of yeast, 321, and footnote
Isolation of ferment, 77
L
Lactic ferments, 5, 36
transformation from and into other ferments (Duval), 37
Lactate of lime, fermentation of, 292
Lechartier and Bellamy, researches on fermentation in fruits, 270
Leptothrix, 36
Liebig’s views of fermentation, 317, and following pages
on fermentation of malate of lime, 321
definition of a ferment, 324
modified theory, 326;
answer to, by Pasteur, 326, 327
neglect of microscopical observations, 329, 330
Lime, bisulphite, use of, by bottlers, 15
carbonate sterilized, use of in growths, 126
dextro-tartrate, 284
acetate and metacetate, 288
lactate, fermentation of, 292
Lister’s, Prof., letter on germ-theory, 43
London breweries, usages of, 8 (footnote)
Pasteur’s visit to, 22-24
“Low” fermentation, meaning of, 9, 10;
advantages, 12
beer breweries, statistics of, 10
properties of, according to Dr. Graham, 13
yeast and “high” yeast distinct, 192, 193
yeast, aspect of, 193;
characteristics, 195
aërobian form of, 215
Low temperatures prejudicial to disease-ferments, 14
M
Malignant pustule, 42
Mashings, 3
Medium, mineral, for growing lactic vibrios, 293, 297 (footnote)
Cohn’s formula, 294 (footnote)
for growth of bacteria, 294
Medium, composition of, influence on life, 296
Microscopical study of yeast important, 23
formerly neglected in English breweries, 22-24
Microscopical examination of vibrios, 298, 299
Microzyma, 121;
source of _mycoderma aceti_ according to Béchamp, 124
Milk, temperature of sterilization of, 34
Milk-sugar, growth of yeast in, 265
_Mother of vinegar_, _v._ mycoderma aceti
Moulds thrive in acid liquors, 36
functioning as ferments, 100, 101, and following pages, 111, 113,
129, 133
growth of, and production of alcohol, 257, 258 (footnote)
suggested employment of, industrially, 261
Mucedines, 36, 40
_Mucor mucedo_ and _racemosus_ on must, 66
_Mucor racemosus_, different aspects of, 105
pure growth of, 128, and following pages
Mucor normal, growth of, 132
weight of to alcohol formed, 134, and following pages
morphology of abnormal growth, 137
_Mucor mucedo_ distinguished from _racemosus_, 140
growth in double-necked flasks, 140, 141
Müntz, 323
Must, fermentation of, always regular, 3
pure fermentation of, 54, and following pages
succession of ferments in, 227, 228
_Mycelium_ and _mycoderma vini_ on wine, 56, 65
Mycoderma in wort experiments, 70
_Mycoderma vini_, arborescent form of, 77
growth of pure, experiments on, 110, and following pages, 120
growth with _penicillium_, 112
with _mucor_, 112
endogenous sporulation, 151 (footnote)
_Mycoderma aceti_ transformations (Béchamp), 124
pure growth of, 124, and following pages
N
_Nageurs_ used in low fermentation, 9
Nature of liquids, influence on growths, 36, 73, 85
Natural liquids for pure growths, use of, 40, 41
experiments on, 47, and following pages
Neutrality, conditions of, as affecting sterilization of liquids, 34;
explanation of fact, 35
Neutralization of acidity in pure growths, mode of, 126
New high ferment, _v._ high
New process of brewing, 391-393
Nitrogenous soluble parts of yeast, 319, 320
Nomenclature used by Pasteur purposely vague, 314
Normal growth of mucor, 132
O
Organic substances, have they any tendency to become organized? 33
Organic liquids sterilized by boiling, 34
Organizable globulines (Turpin), 123
Organisms and animal diseases, 42
_Ouillage_, 2
Oxidation of germ-free liquids, 57
processes of fungi, 261, and footnote
of wort, excessive, injurious, 353, 354
Oxygen absorbed by blood, 50
by urine, 50
and fermentation, according to Gay-Lussac, 60
store-energy imparted to cells by, 134
no influence upon fermentation, (Béchamp), 178 (footnote)
function in fermentation, experiments on, 238, and following pages
influence on fermentation (Schützenberger and Pasteur), 253, 254
amount absorbable by yeast, 255
deficiency of, function in fermentation, 259
influence on products, 100, 108, 113
influence on morphology of moulds and ferments, 105, 106, 133, 137,
262
necessity of, to growth of yeast discussed, 280
unnecessary and adverse to vibrionic life, 284, and following pages
necessary to bacterial life, 305
removal from solutions by bacteria, 295
growth of vibrios apart from, 302
compressed, influence on ferment life, 324
determination of, in worts (Schützenberger), 355, and following pages
solubility-coefficients in water (Bunsen), 360
usual amounts in solution in brewers’ worts, 366, 367
changes in amounts during brewing processes, 369, 370
combination of, with hopped wort, 371, and following pages
experiments on rapidity of combination, 376
on amount of, under brewing conditions, 379
in combination with wort not available for yeast, 380, 381
clarification of wort by, 385
P
Palate-fulness definition, 354, and footnote
impaired by oxidation, 354
Parasites and their germs, 40
influence on animal diseases, 41
Pasteur’s repetition of Trécul’s experiments, 98, 99
subject of his inquiries stated, 311
experiments, exactness of, 95 (footnote)
Pasteurization, meaning and use, 15 (footnote)
Patches of froth in growth of pure yeast, 31
_Penicillium glaucum_ on must, 66
growth of pure, 86, and following pages
precaution, 89
transformed into ferment (Trécul), 94
spores, varieties of, 97
production of alcohol by, 99, and following pages
transformation into mycoderma, 109
Phenol for purifying yeasts, 232
Pitching, mode of, for pure beer, 342, and following pages
flasks, 344
peculiar in London breweries, explanation, 350, 351
Plaster of Paris and yeast powder, 81, and following pages
_Ploussard_ grapes, experiments on, 161
Polymorphism of organisms, 84 (footnote), also _v._ transformation
Precautions for pure fermentation of must, 64
brewers’, to check disease-germs, 220, and following pages
for pure anaërobian growth of yeast, 248
Preservation of yeast, 207
Preoccupation of liquids by organisms, 36, 109, 220
Products of fermentation variable, 276, 277
Price of beer as affected by losses from disease, 24
Proliferous pellicles, 121
Proportions of alcoholic products variable, 276, 277
Proportions of products diagnostic of the fermentation, 279
Proteic matter elaborated by cells, 335
“Pulling up,” 343
Pure growth of yeast, precautions for, 29-32
growths in natural liquids, 40, 41
wort and ferment, advantages of, 391-393
Purification of mixed ferments, 226, and following pages
practical methods, growth in sweetened water, 230
shallow basins, 231
in acid and alcoholic liquids, 231
with aid of carbolic acid, 232
Putrid wort, ferments of, 5
Putrefaction prevented by use of sterilizing flask, 27
of yeast, cause of, 221
of tartrate of lime, 291
Q
Qualities of “high” and “low” beers, 12, 13, 19, 196
Quality of beer dependent on kind of ferment, 26, and following pages
R
Racking, 222
precautions necessary in, 351
Raulin’s fluid, 88 (footnote)
improvement on Schützenberger’s oxygen process, 356, and following
pages
experiments on solubility of oxygen in worts, 361-363
Rayer on splenic fever, &c., 42
Reducing action of vibrios, 291
Rees, Dr., 150 (footnote)
Refrigerator, Baudelot’s, 387 (footnote)
Revival of mould-cells by aeration, 130, 131 (footnote), 138
Revival of starved yeast, 148, 208
vibrios, 301, 302
Ripening of fruits, 270, 271
Robin, Ch., mentioned, 93;
strictures on Pasteur, 310, 311
recantation of views on fermentation, 314
S
_Saccharomyces apiculatus_, 71, and footnote, 150
_exiguus_, 185,
_ellipsoideus_, 165
_pastorianus_ 151;
mode of growth of, 167
two aspects, globular and filamentous, 168, 169
exhaustion and revival of, aspects, 172, and following pages
occurrence as impurity in most ferments, 225
most suitable for growth experiments in sugar solutions, 332
_Saccharomyces pastorianus_, _ellipsoideus_, _apiculatus_ in must, 227,
and following pages
_Sang de rate_, 43
Schützenberger on budding of yeast, 146, and footnote
Schützenberger’s strictures on Pasteur’s views answered, 252, and
following pages
process for determining oxygen in solutions, 355
Seasons, influence on success in brewing, 25
at which germs are absent on fruits, 58, 59
Secondary fermentation in English beers, 224
_Senescence_ of yeast cells, 208
gradual of yeast cells, experiments on, 245
Shallow basins for purification of yeasts, 231
Sodium hydrosulphite, _v._ hydrosulphite
Solubility-coefficients of oxygen in water (Bunsen), 360
in worts (Raulin), 361-363
Sour beer, ferments of, 5
Soundness of beer always dependent on purity of yeast, 26, 32
Specialization of ferment-variations, 197
Specimens, necessary precautions for taking, 126 (footnote)
Splenic fever, 42
Spontaneous fermentation used in must, not in beer, 4
fermentation or putrefaction prevented by use of sterilizing flask,
28
ferment, definition of, 182;
experiment on, 184
generation, facts against, 51, 52, 57
supported by experimental errors, 62, 63
(Trécul’s theory of), 94, 95
impregnations, 65, 66, 69, 73, 79
use in isolating ferments, 77
Spores on grapes, gooseberries, &c., 54
of fungi widely distributed, 68
Statistics of breweries, 10
of French beer consumption, 17 (footnote)
Starved yeast, appearance of, 148
Stability of sterilized liquids, 286
_Stemphylium_ spores, 55 (footnote)
Sterilizing apparatus, 27, 29, 285
flask, 28
Sterilization-temperature of various liquids, 34
Stock beer, 223
Store beer, must be surrounded by ice, 16
Straw wine, peculiar fermentation of, 166
_Strength_, Pasteur’s use of word, 354
saving by the new process, 394
Submerged _penicillium_, 99
_aspergillus_, 101, and following pages
_mycoderma_, 111, 113, and following pages
_mucor_, 129, and following pages, 133
Submerging growths, precautions for, 91 (footnote)
Succession of transformations (Trécul’s scheme), 93, 94
Sugar decomposition by submerged cells, 114
different modes of, by different cells, 115
decomposed disproportionate to yeast formed, 237, and following pages
variation of disproportion in different cases, 249
amount decomposed in a given time, as an index of fermentative energy
(Schützenberger’s views), 252
solutions pure with mineral salts, growth of yeast in, 317, and
following pages
denial of the fact by Liebig and reply by Pasteur, 328, 329
Surface growth of yeast in pure culture, 31
Sweetened water for exhausting yeast, 169, 170, 190
for purification of yeasts, 230
T
Tartrate-acid of potash for purifying yeasts, 231
-dextro of lime, fermentation of, 284, and following pages
products of, 288
ferment of, 290
Temperatures in use in London breweries, 8 (footnote)
high, prejudicial to quality of “low” beer, 19
at which disease-ferments perish, 20;
differs in different liquids, 34, 96
influence on fermentation, 129
Temperatures suitable for “high” or “low” yeasts respectively, 192
influence of on mixed “high” and “caseous” yeasts, 203
for observing active vibrios, 299
Theories of generation opposite stated, 397
Tieghem, Van, on ammoniacal urine, 45
Torula, sense in which used, 73 (footnote)
varieties of, 77
non-fermentative species, 78
Transformation of ferments, according to Duval, 37
of non-fermentative to fermentative impracticable, 80
of _penicillium_ into yeast impracticable, 91
of ferment into moulds (Hoffmann), 92
series, Trécul’s scheme of, 93, 94
of _penicillium_ to _mycoderma_ (Ch. Robin), 109 (footnote)
of _mycoderma vini_ refuted, 113 (footnote)
Turpin’s system of, 122, and following pages
of _mycoderma aceti_ (Béchamp), 124
historical account of views on, 128 (footnote)
of _mucor_ (Bail), 127
of filamentous into globular yeast, 169
of yeast into _penicillium_, &c., impracticable, 333-335
mutual of low and high yeast, discussed, 192, 193
of “high” yeast into “caseous” ferment illusory, 203
of albumen, theory of the vintage, 272, 273
theory disproved generally, 273 (footnote)
Traube, Dr., on ammoniacal urine, 46
researches on fermentation, 282
theory of fermentation, 283 (footnote)
Trécul and Fremy, _v._ Fremy
Trécul’s theory of successive transformations, 93, 94
details of transformation experiments, 98
theory refuted, 99
_Trousseau_ grapes, experiments on, 162
“Turned” beer, ferments of, 5;
filaments of, 23
“Turning out,” 367 (footnote)
Turpin, M., mentioned, 92
Turpin’s system of transformations, 122, and following pages, 113
(footnote)
Tyndall, letter to Pasteur, 399-401
U
Unsoundness of beer correlated with disease-organisms, 26, 32
Urea-ferment, the transformation of (Duval), 37
Urine, ammoniacal, 45, 46
Urine, sterilized, study of, 49, 50
V
Variability of fermentation products, 277
Variations of ferment strengthened and established, 197
Varieties of yeast, 149, and following pages
Vaureal, De, budding of yeast, 146 (footnote)
Vegetable distinguished from animal organisms by ammonia (Robin), 312
Vesicular tissue (Turpin), 123
Vibrio, 36;
butyric, 65, 70
also an example of anäerobian life, 282, 284
active and exhausted, 290
reducing action of, 291
Vibrionic ferment of tartrate of lime, 290
Vibrios, _head_ of, 292;
supposed reproductive corpuscles, 306
growth of, in lactate media, 293
medium for growth of, according to Cohn, 294 (footnote)
not genetically related to bacteria, 296
of butyric fermentation, description of, 298, 300
mode of examining microscopically, 298
fissiparous division of, 299
measurements of, 300
cannot live on butyrates, 301 (footnote)
revival of, 301, 302;
anaërobian growth of, 302
life of, destroyed by oxygen, 303, 304
Vigour of ordinary brewer’s yeast, 246
_Vin de paille_, 166
Vinegar, temperature at which it is sterilized, 34
Vinous flavour in stock beer, 224
Vintage, varied conditions of, 268 (footnote)
fermentation, theory of, according to Fremy, 272, and following pages
Viscous wort, ferments of, 5
Visit to London brewery by Pasteur, 22-24
Vital processes of ferment exceptional, 237
activity of yeast apart from air, 259
potential in cells, 278
Vitiation of experiments, causes of, 63, 85, 92
W
Wad-dressing, antiseptic, 44
Water, hard, influence on aspect of yeast, 194 (footnote)
Weights of _mucor_ and alcohol, proportion of, 134, and following pages
Weight of yeast grown, what due to, 257 (footnote)
Wide dishes, experiments on fermentation in, 69, 70
favourable to mould developments, 75 (footnote)
Wine, less liable to deteriorate than beer, 2
temperature of sterilization, 34
Wort, definition, 2;
cooling of, 3, 4
temperature of sterilization, 34
solubility of oxygen in, 361, and following pages
formula for solubility in any wort, 364
Worts, brewers’, usual amounts of oxygen in solution, 366, 367
experiments on amounts, 379
Wort, hopped, its affinity for oxygen, 371, and following pages
mode of transmitting it free of oxygen, 371, 372
insoluble substances in, 386
Y
Yeast, _v._ also ferment, germs, torulæ nature and properties of, 143,
and following pages
starved and well-nourished, appearances contrasted, 147, 148
varieties of, 149, and following pages
commercial origin of, where? 187
relations to other organisms, 180, 181
commercial mixtures, 224, 225
practical purification of, 230-233
impurities in masked for a time, 220
exceptional characteristics of, 237
growth of in sterilizing flasks, 29-32
not transformable into any other organism, 37
aspect may change under modified circumstances, 37
non-transformation of _mycoderma vini_ into, 120
_mucor_ into, 132
non-fermentative species of, 79, 80, 206, 207
“high,” characteristic aspect of, 188-192
well aerated, fungoid mode of growth, 251
anaërobian growth, cause of fermentation, 259
growth of, in solutions of sugar, 318, and following pages
growth in relation to proportion of sugar used, 237, and following
pages
difficult propagation in saccharine mineral media, 329, 330
growth of, without producing alcohol, 265
capacity of absorbing oxygen, 255
necessity of oxygen for its growth discussed, 280
incapable of using oxygen in combination in worts, 380, 381
soluble nitrogenous part of, 320, 321, 79 (footnote)
dried into dust still active, 81, and following pages
does not perish at temperatures at which disease-ferments do, 20
sudden inactivity of, cause and cure, 347 (footnote)
change of, a trade custom, 22
reason of addition of yeast to wort, 3
proportion commonly added, 3
reason of the large proportion used, 343.
Yeast-cells abundant in brewing laboratories, 75
gradual senescence of, 245
Yeast-cells, mode of examining fruits for, 267 (footnote)
necessary relation to “alcoholic fermentation,” 275
Yeast-water, definition, 79 (footnote)
exhaustion of yeast by, 171
use of in pure growths (_penicillium_), 88
“Youth” of cells, 246
_Pardon & Sons, Printers, Paternoster Row, London._
_WITH NUMEROUS ILLUSTRATIONS._
WINE:
_A TREATISE ON ITS ORIGIN, NATURE, AND VARIETIES_.
BEING A
COMPLETE MANUAL OF VITICULTURE AND ŒNOLOGY.
BY
J. L. W. THUDICHUM, M.D.,
AND
AUGUST DUPRÉ, PH.D.
_Medium 8vo. 25s._
“A treatise almost unique for its usefulness to either the grower, the
vendor, or the consumer of wine. The analyses given are the most
complete we have yet seen, exhibiting at a glance the constituent
principles of nearly all the wines known in this country.”—_Wine Trade
Review._
“We have little doubt that this volume will be regarded as the standard
English work on the subject by those whose business is connected with
wine.”—_Chemist and Druggist._
“A perfect magazine of information, procured from first sources, and
intelligently digested.... This exhaustive treatise deserves a cordial
welcome alike from the wine grower, the wine merchant, and the consumer,
all of whom cannot fail to consult it with advantage.”—_British Trade
Journal._
ON THE
USES OF WINE IN HEALTH AND DISEASE.
BY
F. E. ANSTIE, M.D., F.R.C.P.
_Crown 8vo. 2s._
MACMILLAN & CO., LONDON.
MACMILLAN & CO.’S PUBLICATIONS.
BY H. CHARLTON BASTIAN, M.D., F.R.S.
THE BEGINNINGS OF LIFE: Being some Account of the Nature, Modes of
Origin, and Transformations of Lower Organisms. In Two Volumes. With
upwards of 100 Illustrations. Crown 8vo. 28_s._
EVOLUTION AND THE ORIGIN OF LIFE. Crown 8vo. 6_s._ 6_d._
A TREATISE ON CHEMISTRY. By Professors ROSCOE and SCHORLEMMER.
Vol. I., The Non-metallic Elements. With numerous Illustrations, and
Portrait of Dalton. Medium 8vo. 21_s._
Vol. II., Metals. Part I. With Illustrations. 8vo. 18_s._ (Part II. in
the Press.)
LESSONS IN ELEMENTARY CHEMISTRY, INORGANIC AND ORGANIC. By PROFESSOR H.
E. ROSCOE, F.R.S. With numerous Illustrations, and Chromo-litho of the
Solar Spectrum, and of the Alkalis and Alkaline Earths. New Edition.
Fcap. 8vo. 4_s._ 6_d._
A MANUAL OF THE CHEMISTRY OF THE CARBON COMPOUNDS, OR ORGANIC CHEMISTRY.
By C. SCHORLEMMER, F.R.S., Lecturer in Organic Chemistry in Owens
College, Manchester. 8vo. 14_s._
A SYSTEM OF VOLUMETRIC ANALYSIS. By Dr. E. FLEISCHER. Translated from
the Second German Edition by M. M. Pattison Muir, with Notes and
Additions. Illustrated. Crown 8vo. 7_s._ 6_d._
PRACTICAL CHEMISTRY FOR MEDICAL STUDENTS. By M. M. PATTISON MUIR,
F.R.S.E. Fcap. 8vo. 1_s._ 6_d._
A COURSE OF PRACTICAL INSTRUCTION IN ELEMENTARY BIOLOGY. By T. H.
HUXLEY, LL.D., Sec. R.S., assisted by H. N. MARTIN, B.A., M.B., D.Sc.,
Fellow of Christ’s College, Cambridge. Crown 8vo. 6_s._
MACMILLAN & CO., LONDON.
● Transcriber’s Notes:
○ Missing or obscured punctuation was silently corrected.
○ Inconsistent spelling and hyphenation were made consistent only
when a predominant form was found in this book.
○ Text that was in italics is enclosed by underscores (_italics_).
○ Text that was in bold face is enclosed by equals signs (=bold=).
○ Footnotes have been moved to follow the chapters in which they are
referenced.
○ Subscripts are transcribed by an underscore and a value enclosed
in braces, such as O_{2}. Superscripts are transcribed by an
up-caret and a value enclosed in braces, such as MC^2, or
sometimes by an up-caret and a single character, such as 4^e.
End of Project Gutenberg's Studies on Fermentation, by Louis Pasteur