2 STUDIES ON FERMENTATION. 



two liquids. The small amount of aciditj' in beer, its povert}' in 

 alcohol, and the presence of matter that is saccharine, or liable 

 to become so, all operate in imparting to beer a tendency to 

 change, which wine does not possess. That this unequal resist- 

 ance to the aggression of diseases is due to such differences, 

 may be proved by the fact that wine could be made much 

 more liable to change than it actually is, by a diminution of 

 its acidity and its usual proportion of alcohol, or by increasing 

 the proportion of viscid or saccharine matters,* modifications 

 which would tend to assimilate its composition to that of beer. 



We have remarked elsewhere that the pains devoted to the 

 rearing of vines, and to the ordinary operations of vinification, 

 such as ouiUaffe,f sulphuring, and repeated rackings, as well as 

 the use of cellars and vessels hermetically closed, are entailed 

 by the necessity of counteracting and preventing the diseases to 

 which wine is liable. The same may be said, a fortiori, of beer, 

 inasmucb as it is more liable to change than wine. Manufac- 

 turers and retailers of this beverage have to strive constantly 

 with the difficulty of preserving it, or the wort used in its 

 manufacture. We may readily be convinced of this hj review- 

 ing the usual processes of the art of brewing. 



When the infusion of malt and hops, which is termed wort, is 

 completed, it is left to cool. It is next put into one or more casks 

 or vats, in which it is made to undergo alcoholic fermentation — 

 the most important of all the processes in brewing. 



The cooling must be as rapid as possible. This is a condition 

 of success ; otherwise, the wort may deteriorate, which will 

 necessarily lead to deterioration in the quality of the beer. As 

 long as the wort is at a high temperature it will remain sound ; 



* One of these modifications is a real source of serious danger to the 

 preservation of wine ; for instance, during rainy years, at the time of 

 vintage, the grapes may happen to be covered with earthy matter, 

 consisting principally of carbonate of lime; this will dissolve in wine 

 and partly neutralize its acidity, and the wine will thus become more 

 liable to disease. 



t Transferring from one cask to another for the purpose of clarifying 

 the wine. 



