This process is much the same whatever kind of meal or flour may
be used, whether wheaten, barley, &c. A certain portion of the
flour is mixed with warm water (in which a little salt is generally
dissolved), some yeast or “barm” (the froth from the fermentation of
beer) is added, and the whole worked together to a pasty consistence,
this is put into a pan to keep warm, and is called “the sponge;”
besides flour and water nearly every baker mixes his sponge with
a certain proportion of potatoes boiled to a “squash,” and passed
through a sieve to separate the rinds. In an hour or so it swells up
to double its original size, from the fermentation which is going on
producing a kind of gas called “carbonic acid,” which being formed
in every part of the “sponge,” inflates it to a great extent. After
a time it sinks down (most of the gas escaping), and begins to rise
again; it is then mixed with the remainder of the flour (and some
water if necessary), and the whole thoroughly kneaded together with
the hands till it is all of an equal consistence--this should be
neither too stiff, nor so soft as to stick to the hands. It is now to
be cut up and weighed out into pieces to form each loaf. The oven in
which the bread is baked is made of “fire-brick,” and so embedded in
earth or brickwork that when heated it shall not readily cool; this
is heated with coal or wood till it is nearly red-hot and the loaves
are put in and left till baked.