FERMENTS AND ARTIFICIAL FERMENTATIONS. 8&1 
order to establish fermentation. The yeast is procured 
by collecting the scum of fermented beer and straining 
it into bags. 
In Belgium, the wort is allowed to stand until the 
spontaneous development of fermentation takes place ; 
but in France and Germany the ferment is generally 
added. In this case two methods are in use, fermenta- 
tion from above, and fermentation from below ; and this 
enables us to distinguish two kinds 
of yeast, that of superior, and that of 
inferior beer (Figs. 45, 47). » Ae 
In superior beer, the saccharifica- ) 3 
tion of the starch of malt is effected , fs) 
by successive steepings in casks at 8 "4 
the relatively high temperature of ci 
from 15° to 18°. As the yeast is pip. a7 —veast of in- 
formed, it gradually issues from the of bugdleg Ce ue 
bung-holes in the upper part of the ca 
cask ;, hence its name. In England, large open vats 
are used: the yeast rises to the top, and- is removed 
with skimmers. 
In the manufacture of inferior beer, saccharifica- 
tion is effected by steeping the malt in open vats at, 
the lower temperature of from 12° to 14°. The 
yeast is deposited at the bottom of the vats in a 
doughy and tenacious mass. When the first and 
most active fermentation is at an end, the clear liquid 
is drawn off and put into casks, bottles, or pitchers, 
and as the separation of the yeast is not yet complete, 
5 
