FERMENTATION. 435 



be judged necessary. In some of the wine countries 

 on the continent, we learn, they cover their vats, to 

 the end that the alcoholic gas or spirit may not be 

 dissipated and lost by fermentation ; leaving, however, 

 a small aperture, through which the aqueous gas may 

 escape. This method, if of any real benefit, is easy 

 enough to be imitated, and will contribute to ensure 

 a thorough fermentation, from the defect of which, in 

 the first stage, our home-made wines are often ren- 

 dered of uncertain quality and condition, or are totally 

 spoiled. Fermentation is the action one upon another, 

 of the component parts of any body or mass, con- 

 taining fermentable materials, the initiating powers of 

 which are acids and alcohol : the commencement of 

 this process, is found to require a temperature above 

 60, but one of eight or ten degrees higher, promotes 

 it effectually. Nevertheless, the aid of yeast and a 

 toast is usually recurred to, at the commencement. 

 Fermentation is sometimes inconveniently prolonged. 

 This may arise from various causes, from its imper- 

 fection in the first instance ; from the original weak- 

 ness and poverty of the must, when the last stage of 

 its condition will be that of acidity ; or from the un- 

 favourable state of the weather. The wine being sound, 

 the usual remedy in the case is, racking it off from the 

 lees, into fresh casks. Beyond this, and after the first or 

 regular species has ceased, a new process commences, 

 styled, perhaps vaguely, the insensible fermentation. 

 This may, with equal reason, be attributed to the 

 gradual changes which the must goes through, in its 

 progress to vinous perfection. The residuum, or lees, 

 an effete material, does not retain the power to fer- 

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