Encyclopaedia Britannica > Volume 7, ETM-GOA

F E R [ 217 ] F E R
fermenta- tlior), I am induced to give the following explanation
tion- of the procefs (making of bread). Yeaft is a fluid
* containing a large quantity of fixed air or aerial acid ;
His expla- ant* ^ie ProPorti°n is greater as the fluid is colder. As
nation of f°on as fhe yeaft is mixed with the dough, heat is ap-
the procefs. plied ; this extricates the air in an elaftic ftate ; and as
it is now diffufed through every particle of dough, every
particle muft be raifed ; the vifcidity of the mafs re¬
tains it: it is now baked, and a ftill greater quantity
of air is extricated by the increafed heat; and as the
cruft forms, the air is prevented from efcaping ; the
water is difiipated : the loaf is rendered fomewhat dry
and folid ; and between every particle of bread we find
a particle of air, as appears from the fpongy appear¬
ance of the bread, owing to the apparent vacancies
which the air had made by infinuating itfelf intp it.”
This explanation he finds alfo confirmed by what is
called the falling of bread after it has once been raifed}
and which takes place fo rapidly, that we cannot fup-
pofe the procefs of fermentation to have been finiflied
in the time: nay, bread will fall before we are war¬
ranted from his experiment to fay that the fermentation
is well begun ; for this, as we have feen, required be¬
tween 9 and 16 hours.
That bread is raifed, not by a proper fermentation,
but by a mere effervefcence or efcape of fixed air, is
likewife evident from feveral fa£ts mentioned by Dr Pe-
nington. In Philadelphia, the bakers find fome diffi¬
culty in getting good yeaft in the fummer-time, on
account of the heat of the weather, which very foon
turns it four. In this cafe, they diffolve a fmall quan¬
tity of potaffi in waterj and mix it with their yeaft ;
when the effervefcence produced between the acid and
alkali produces fuch a difcharge of fixed air, as raifes
the bread in lefs than ten minutes. He informs us al¬
fo, on the authority of Dr Rufli late profeffor in the
college of Philadelphia, that “ near Saratoga there
are two mineral fprings, the waters of which have all
the properties of the famous Pyrmont water, being
highly impregnated with fixed air. When this water
is mixed with flour into dough, it is fufficient, with¬
out yeaft, to make a very light and palatable bread.”
A third fail is ftill more decifive. “ I procured (fays
the Doitor) fome nice cryftals of the fait formed by
the foffile alkali and fixed air, and diffolved them in
water fufficient to make a fmall loaf of bread. To
this I added a little of the marine acid, commonly
called fpirit of fea-falt; fixed air was generated, but
was abforbed by the cold-water; it was then mixed
with flour, fet in a warm place to rife, and fhortly af¬
ter baked ; and I had the exquifite pleafure to obtain
a tolerably light loaf of bread, fuch as any one would
have fuppofed to have been fermented, which was
feafoned by the fea-falt, formed by the union of the
foffile alkali and fpirit of fea-falt; whilft the fixed
air of the foflile alkali was difengaged, in order to
^ raife it.”
Other fads To thefe inftances mentioned by our author we ffiall
in confir- add two others, which (how that fixed air is not even
niation of neceffary to the raifmg of bread ; and of confequence
his opinion. we cannot fUpp0fe that fermentation, which produces
a great quantity of it, is the foundation of the procefs.
One is, that eggs, when beaten into a froth, areffome-
times made ufe of for railing bread ; but more efpe-
cially for puddings, &c. in which they perfqrm an
Vol. VII. Part i. '
operation fimilar to that of railing and rendering bread Fcrtnenta-
light and fpongy. This is done by the rarefaction of “on
the particles of air enveloped among the glutinous par- ’ 1' '_r.
tides of the egg: and hence fnow, on acccount of its
porous and fpongy nature, containing a’great quantity
of air enveloped amongft its particles, will do the fame
thing. This laft particular was lately publilhed by
Dr Rotheram of Newcaftle.
With regard to the other experimen ts of Mr Henry, His obfer-
they feem to Dr Penington not to be altogether con- 0:1
clufive. He doubts the juftice of Mr Henry’s idea, T^s
“ that wort cannot be brought into the vinous fer- ments.
mentation without the addition of a ferment.” When
we confider the analogy betwixt the infufion of malt
and other fermentable liquids, the Doctor fuppofes
that wort, as well as they, might fpontaneoufly fall
into a ftate of fermentation. He fays indeed, that he
has not as yet been able to difprove the idea by expe¬
riment : but Captain Cook has already made the ex¬
periment, and the event has decided the matter in the
Do&or’s favour*. We are told by that cdebrated * See the
navigator, that the infpiffated wort would have an- article Cooi,
fwered the purpofe excellently, provided it could have vo1'v- p"
been kept from fermentation in its infpiffated ftate. ^4’ COl‘ *’
But this was found impoffible: of confequence we
muft: conclude, that wort, as well as other liquors, will
fall into a ftate of fermentation fpontaneoufly, though
perhaps not fo readily, or with fuch a fmall degree of
heat, as other fermentable liquors. Hence we are not
altogether certain, as Dr Penington hints, whether the
fermentation in Mr Henry’s experiments might not
have taken place without it. “ In the memoir (Mr
Henry’s) above mentioned, fays the Dodlor, the au
thor feems to think, that fxed air is the true caufe of
fermentation in vinous liquors ; and he tells us of the
excellent tafte afforded to punch by being impreg¬
nated with it. Fixed air, it is well known, improves
the tafle of liquors; but we cannot fufpwff that it made
the punch ferment in his experiment: but he tells us,
that he made an artificial yeaft; that with this yeaft
he made beer (perhaps he might have made it with¬
out it) and vinegar; and that he fermented bread with
it. As for its fermenting bread, we might readily
allow that it would raife bread, upon the principles
already laid down : and when he tells us how quick
the fermentation takes place in his liquors when ex-
pofed to a-gen tie heat, may we not juftly fuppofe, that
the warmth extricated the fixed air that he had ar¬
tificially combined with it, and that from this pheno¬
menon alone he had fuppofed fermentation to be going
on in them ? Fixed air is the caufe of the briflenefs,
pungent tafte, and fparkling appearance, of vinous li¬
quors ; and it is remarkable, that, in equal Circum-
ftances, the colder they are, the more air they con¬
tain. It is alfo a curious fa&, that the fixed air in
liquors muft be in a peculiar ftate, otherwife they do
not poffefs that brilknefs or pungency we (poke of;
in fa£l, it muft be on the point of affuming its elaftic
form: hence liquors are not fo brilk in cold as in warm
weather; and a connoiffeur in porter, for inftance,
will tell you, that a bottle (hall open very brilkly in a
warm day ; and upon the coming on of cold weather,
all the reft (hall be flat and dead ; but let them be
corked up and kept in a warm room for a few days,
they will all recover their former ’brilknefs; nay, I
£ e have