10 ON THE ART OF MAKING WINE. 



the sugar predominates, the wine will be sweet, 

 unless expedients are used to complete the fermen- 

 tation of the sugar, and convert the whole into 

 wine. If the sweet principle is most abundant, 

 pr, to speak more correctly, if there is much vege- 

 table extract combined with the sugar, the fer- 

 mentation will be complete, and the wine dry, un- 

 less artificial means, hereafter to be described, are 

 used to prevent this effect. The distinction which 

 I have here drawn, though appearing to partake 

 of unnecessary refinement, will be found to lead to 

 practical utility, 



Among the enumerated ingredients of fruits, the 

 vegetable extract naturally falls next under con- 

 sideration. Although this substance has not been 

 analyzed, we know that it differs from mere vege- 

 table mucilage, by containing azote, or a sub- 

 stance which on decomposition produces it, since 

 azotic gas has been detected in the produce of fer- 

 mentation, both in arj uncombined state, and in 

 one of its, most frequent combinations, forming 

 ammonia. These substances are known to ex- 

 ist in yeast, which is a modification of the veget- 

 able extract, In many vegetables, and conspicu- 

 ously in the gluten of wheat, it exists in great 

 proportion. It is for this reason that wheat as 

 well as rye, act powerfully as ferments. It is al- 

 o found in many flowers, in that of the elder for 

 , in the leaves of the vine, in 



