436 
AERATION, 
The operation of running the grapes through the stemmer ana 
cru: her, it has been noticed, results in a better aeration of the must, 
as the bunches of grapes are vigorously tossed about during that 
process, with the result that the skins burst, and, after passing 
through the rollers, the berries are reduced to a state of pulp. 
Pasteur demonstrated that one of the main factors in the 
mataring of the wine is the oxygen, which is readily taken up by 
its constituents and by them held in a state of loose chemical com- 
bination, from which it is readily given up as required. A 
phenomenon of a similar nature occurs in the case of the grape 
juice; under the influence of warmth and the oxygen absorbed by 
the liquid, the process of maturation of the grape is consummated 
inside the vat, and the must is thereby enriched by the full amount 
of fermentable grape sugar it is capable of acquiring. 
Although the must absorbs much air during the operation of 
cru hing, it is often considered advisable to further aerate it prior 
to setting it to ferment. 
The influence of aeration in quickening the starting of fermen- 
taticn is now well understood by the wine makers of the old world, 
and various designs, as well as special appliances, are employed in 
cariying out that process, both in the making of red and of white 
wines. 
Among the advantages which result from the aeration of the 
must, or mash of grapes, before it is turned into wine, the following 
may be mentioned :— : 
(1.) The cooling down of hot must obtained from grapes 
picked during the hottest hours of the day. 
(2.) A greater regularity in the progress of fermentation. 
(3.) Its earlier completion, hence less exposure to the air, and 
therefore less risk of contamination by injurious 
microbes which float in the air. 
(4.) The quicker clearing of the young wine. Aeration or 
oxidation causing the precipitation into the lees of some 
of those rapidly-deeomposing white-of-egg-like or albu- 
minoid matters in the must, which afford a favourite 
food for dangerous microbes. 
As an instance of this, I may just mention that in the Depart- 
ment of Meurthe, in the North-West of France, where the grapes 
con’ain much albuminoid matter, aeration is carried on systemati- 
eall,, as one of the processes of wine-making. For this purpose the 
must is thoroughly stirred by means of shovels, till the air is well 
mec rporated through its mass, and such wine, which is known as 
vin de pelle (shovel-made wine), by reason of its superior quality, 
