acid gas, are produced.

The different stages of fermentation are noted scientifically as
alcoholic, acetous, and putrefactive. The first is the name given to the
change which takes place in the saccharine matter of the dough, which
results in the formation of alcohol and carbonic acid gas. This same
change takes place in the saccharine matter of fruits under the proper
with conditions of warmth, air, and moisture, and is utilized in the
production of wines and fermented liquors.

In bread-making, the alcohol and carbonic acid gas produced during the
fermentation, are formed from sugar,--that originally contained in the
flour and the additional quantity formed from starch during the
fermenting process. It is evident, therefore, that bread cannot be
fermented without some loss in natural sweetness and nutritive value,
and bread made after this method should be managed so as to deteriorate
the material as little as possible.

If this fermentation continues long enough, the acetous fermentation is
set up, and _acetic_ acid, the essential element of vinegar, is formed
and the dough becomes sour. If the process of fermentation is very much
prolonged, the putrefactive change is set up, and the gluten is more or
less decomposed.

If the dough be baked during the alcoholic and carbonic-acid stage of
fermentation, the gas will render the loaf light and porous. The alcohol
will be dissipated by the heat during the baking, or evaporated shortly
afterward, provided the baking be thorough. If the fermentation is
allowed to proceed until the acetous fermentation has begun, the loaf,
when baked, will be "sad" and heavy, since there is no longer any gas to
puff it up. If, however, during the first or alcoholic stage of
fermentation, new material be added, the same kind of fermentation will
continue for a certain period longer.

These facts serve to show that great care and attention are necessary to
produce good bread by a fermentative process. If the fermentation has
not been allowed to proceed far enough to generate a sufficient amount
of gas to permeate the whole mass, the result will be a heavy loaf; and
if allowed to proceed too far, acid fermentation begins, the gas
escapes, and we have sour as well as heavy bread. It is not enough,
however, to prevent bread from reaching the acetous or sour stage of
fermentation. Bread may be over-fermented when there is no appreciable
sourness developed. Fermentation may be carried so far