458 
marks, according to the lesser or greater degree of sweetness it is 
desired to give to the wine, 2deg. to 4deg. Baumé, which would 
leave in the wine 34% to 7 per cent. of unfermented sugar. 
The formula for fortifying wine is given on page 433. 
Rearing oF Youna WINES. 
After three to five days the fermenting wine, having been drawn 
from over the skins, is pumped into another receiver vat or cask 
to complete its fermentation. 
A crackling sound, caused by a slow fermentation, keeps on for 
some little time, and as carbonic acid gas is given off, the casks 
should not be plugged tightly, lest they should burst. A good plan 
is to place over the bung-hole a small flat sand-bag, a few inches 
square, which, while not interfering with the escaping of the gas, 
keeps dust, germs, and the troublesome minute fermentation flies 
dropping into the cask. 
To the same effect, specially constructed bungs are sometimes 
used. 
The carbonic acid gas under tension from inside the cask forges 
its way out through the perforated plug which fits tightly into the 
bung-hole, and,, overcoming the pressure of small layers of water, 
into which an inverted glass bell stands, escapes outside, whereas 
Showing Hydraulic]Plug for wine casks. 
the external air and all the impurities it carries in suspension, 
cannot get access to the wine in the eask. 
Such plugs, although useful, are not indispensable to the safe 
keeping of well fermented voung wines. 
After a rest of two or three weeks it loses its turbid look and 
casts the dead yeast cells and other impurities which collect as lees 
