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during the process of fermentation are deeper in colour than those 
fermented at a cooler temperature. If moderate temperature helps 
in dissolving the colouring matter of grapes, it causes it, if carried 
on to a higher degree, to undergo an alteration which brings about 
its precipitation. 
An instance of this is afforded by wines which, during the 
process of sterilisation by means of heat-process, known as pas- 
teurisation, has been over-heated. That point is reached at about 
70° C. (158° F.), and for that reason it is desirable not to go much 
above 65° C. (149° F.). 
Each variety of grape has a special pigment of its own, 
peculiar to itself. 
Albuminoids or nitrogenous substances, resembling the white of 
an egg, also occur in minute quantities, viz., .1 to .4 per ecent., and 
are important. To a certain extent, therefore, they are essential to 
fermentation, but when constituting a surplus their presence in 
wine is highly undesirable, and even dangerous, as they are very 
unstable bodies, easily decomposed, causing many of the accidents 
and diseases which occur in wines. 
Certain grapes, such as the Riesling, various white grapes, and 
also Muscats, often contain a surplus of these albuminoid bodies, 
and, especially so, grapes that mature very quickly, as in hot 
climates; and this is the case generally with grapes grown in 
Australia. 
Such surplus albuminoid substances should be removed by all 
possible means, in order to insure the safe keeping of wines; and 
in a subsequent paragraph I shall mention the object of aeration 
in this respect. 
Another means we have of ridding white wine must of any 
surplus albuminoid matters is to let it stand still for a day or two, 
and then draw the clear liquid from over the muddy and viscous 
deposit just as the first indications of fermentation become notice- 
able. In order to better effect this end in warm climates, where 
fermentation starts very shortly after the grapes are crushed, the 
liquid is treated with sulphurous acid fumes. Thus the must is 
impregnated with the fumes of burning sulphur, or liquid sulphur- 
ous acid in small quantities is poured into it, or such salts as sul- 
phite of potassium is added to it. The advantage of these last- 
named methods over the first consist in the greater precision which 
ean be obtained in the matter of the dose used, and in the greater 
convenience as well. 
Wuen to Pick GRAPES. 
In old-established districts experience has shown when it is best 
to pick the grapes; and at such places it is seldom that the date 
of vintage alters more than a week or so from the customary epoch 
for picking the different kinds of grapes grown. 
