214 ALCOHOL, VINEGAR, SAUER KRAUT, TOBACCO, SILAGE, FLAX. 
produce a vigorous action. Yeast is sometimes added. As a rule, 
the fermentation is allowed to continue as long as it will, after which 
the wine is bottled and thus preserved for use. 
Cider. This is nothing but apple wine, and is made in large 
quantities in sections of the country where apples are abundant. 
The expressed apple juice is seldom treated at all, but left to ferment 
spontaneously. The amount of sugar in apple juice is small, and 
the completely fermented product contains a proportionately small 
amount of alcohol. Sweet cider is a name given to the product 
while it is still fermenting; it contains but a small amount of alcohol, 
but is filled with the carbon dioxid gas that is produced by the 
fermentation. Hard cider is the name applied after the fermenta- 
tion is nearly or quite over, when the evolution of CO 2 has ceased 
and the alcohol is at its maximum. In the making of cider, as in 
most other fermentations, great improvements have been made in 
recent years by the application of the discoveries of bacteriologists. 
The use of pure cultures of yeasts, in the place of spontaneous 
fermentation, makes the product of a better character and the fer- 
mentation more uniform. Numerous other improvements have 
been made in the details, so that this product, formerly made on the 
farm in a haphazard fashion, without care and with little or no 
knowledge of the processes, is now made on a larger scale in special 
cider factories, resulting in a cider of a much higher quality. 
Yeasts in Bread Raising. The most common use of yeast 
is in the raising of bread. All nations and all peoples have been 
accustomed to make bread from the flour of different grains. The 
earliest method was simply to stir the flour in water and bake 
the mixture into a hard, unleavened bread. The next step was 
to allow the dough to stand for a number of hours in a warm place 
until it became somewhat swollen by the gas formed within it, 
and then to bake it. The gas made the dough porous and resulted 
in a bread filled with holes, easier to masticate, of better flavor, and 
more easily digested. This was leavened bread. The next step 
was to take a little of the leavened dough and mix it with the next 
lot of fresh dough, to hastenen the leavening, a process that was 
simply inoculating the dough with the yeast organisms in the 
