Jf«r. 2, 1908.] Agricultural Gazette of N.S.W. 239 



You understand that 5 cwt. of grape sugar that is split into alcohol, 

 carbonic acid, etc., must fatally produce a certain quantity of heat, which is 

 the same, no matter what is the initial temjierature at which fermentation 

 begins; whether it begins at 60° Fahr. or at 80° Fahr., the amount of heat 

 produced by 5 cwt. of grape sugar turned into alcohol and the other ingredients 

 is always the same. 



Howevei', if the must is cool wdien Ijeginning to fei-ment, then the heat 

 produced by fermentation will not cause the temperature in the vat U) rise 

 beyond the limits best adapted to the life of the yeast ; but if the grape-juice 

 is already fairly hot, then it gets nuich too hot for the yeast to perform the 

 best work of which it is capable. 



What are these limits ? They are between 75° to 90'^ F'ahr. ; even 92' or 

 93° Fahr. may be reached without the wine suffering in qnality. 



There are onh' two ways to secure that fermentation should take place 

 within the proper temperature limits. 



One is to pick the grapes early in the morning, and suspend picking during 

 the hot hours of the day. In this way the juice starts fermenting at a 

 relatively low tem})erature, and the rising of the initial temperature of the 

 must will not reach or go beyond the limit. 



Naturally, gathering the grapes only early in the morning would ])rotract 

 the vintage too long ; and if the method may be applied by the wine-grower 

 in a small way of business, the man with large vineyards cannot do it. 

 Then special devices should be adopted, so as to eliminate the increasing heat 

 from the vat. 



Readers of the Gazette will find a description of several methods of how to 

 control the teinpi^rature of the fermenting grape juice in some of my previous 

 articles, viz., "Modern Processes of Vinification," January, 1902; "The 

 tStal.ility of the Colouring Matter in Red Wine«," January and February, 

 1903; "Licit and Improved Treatment of Grape-juice in Wine Making," 

 January, 1906. 



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