286 GRAPE CULTURE AND WINE-MAKING. 



But very few know besides that during its action originate two 

 distinct new agents from its sugar parts that had not been pres- 

 ent in the must, viz., alcohol^ remaining in the product and impart- 

 ing to it its strength, and oxygen^ which chiefly evaporates. But 

 the real cause that transforms the sugar parts into these — or, rath- 

 er, in the case of grape fermentation, into v:inc — is still a profound 

 •secret. 



In the following paragraphs Dr. L. Gall proposes to give some 

 contribution to the knowledge of the conditions under which those 

 actions take place in the most perfect way, if by them wine is to 

 be produced : 



The fermented must becomes wine not before all those parts 

 have been secreted that do not properly belong to the latter and 

 peril its durability. It does this, indeed, by itself in the course 

 of time; but it must be a main object of modern industry to pro- 

 duce such an end not only ivell^ hut also cheaply ; i. e., avoiding as 

 far as possible the expenditure of capital, material, time, and labor. 



A mean temperature of 10° or 12° R. was formerly generally 

 considered sufficient for the whole period of the fermentation of 

 must. Numerous facts prove, however, that this can not be con- 

 sidered as a proper standard, as it has been observed, as Chaptal 

 mentions, that, according to exj)eriments made by Mr. Poitevin, 

 the heat originating in a certain quantity of grapes increased with- 

 in five days to 26f per cent., and the fermentation ceased after 

 fourteen days at 22 per cent. 



From this we may draw the following consequences : 



1'. That larger quantities of grapes, very rich in sugar, attain a 

 heat of 26f per cent. ; this temperature, consequently, has to be 

 taken as the most favorable for fermentation. 



2. That as the heat of the fermenting must originates by the 

 changing of the sugar into alcohol and oxygen, thereby develop- 

 ing warmth, this necessarily must reduce itself by degrees as less 

 sugar remains to decompose. 



3. That it is policy to aid the natural fermentation toward its 

 end by gradually increasing the temperature of the fermentation 

 room (locality), and, on the contrary, protect it from cooling off. 



Many experiments by Dr. L. Gall and others have settled it 

 that: 



1. The mash of red grapes of 18 to 25 per cent, sugar heats it- 

 self (when the outer air is excluded), at a temperature of 14° to 15° 

 of the mash-room, up to 20° to 23° R. ; the must of vMte grapes 

 of like sugar per centage only to 20° or 21° R. 



2. That the fermentation falls oflP as soon as, at an equal exte- 

 rior temperature, the warmth of the fermenting mass sinks 2° or 

 3° ; but after two or three days (so long as all the sugar is not 

 yet decomposed) begins anew, continuing for several days more 

 if the secreted mash is stirred up again with the whole mass. 



3. That the fermentation appears to finish sooner, and all the 



