353 



ent ways, act to i^roduce remarkable transformations in organic 

 bodies. 



The second change, which demands attention, is that of the 

 conversion of dextrine and glucose, — the sugar of fruits, — into 

 alcohol, which remains dissolved in the Huid. This breaking up 

 and rearranging of the elements of sugar is effected, as is well 

 known, through the aid of the heer yeast plant, usually. Like dias- 

 tase, the beer yeast pliant is endowed with life, and has the power 

 of communicating motion to organic and organized matter, result- 

 ing in change of composition. In so simple an expression of the 

 phenomena of beer, or wine production, we have omitted some 

 most important substances, which participate in the changes. 

 These are the natural fixed oils and fats, and the volatile odorous 

 bodies, in grains ; but more especially in grapes, fruits, cane pro- 

 ducts, ^c. Thus the hop extract, added before fermentation, to 

 ale, beer, or porter, becomes altered, as do the grape oils ; and 

 the remark applies to all known cases of fermentation of mixed 

 solutions. Mature grapes contain a natural ferment, in its appro- 

 priate cells, requiring, to bring its affinity in view, only that the 

 cell walls and tissues of the fruit be broken, so as to provide fluid 

 sugar, on which it reacts. Fermentation, which at a temperature 

 of 70° F. commences immediately in grape juice, developes be- 

 sides alcohol a whole class of new bodies. So in the fermen- 

 tation of grains, the fixed bland oils of the seeds, slightly altered, 

 remain ; while more volatile odorous oils are directly produced 

 from materials present. Now, these oils deserve special atten- 

 tion, because on the production of these, and their subsequent 

 further change, the money value of the beverages depends. A 

 very large consumption of beverages is supplied by the first fer- 

 mentation of the materials named, and these alcoholic mixtures 

 also form the basis of the spirit manufacture. 



The second fermentation of wines is perhaps more important 

 than the first. In this, the alcohol remaining almost unaltered, 

 the greatest changes take place in the fruit extracts and oils. 

 Fruit extracts lose their acidity and much saline matter, while 

 the presence of acids leads to the production of ethers, from oily 

 bases present, which then give their odors to the wine. It is 

 apparent that the proportions, and even kinds of ethers present, 

 may vary ; but a general predominance of one designates a wine. 



PROCEEDINGS B. S. N. H. VOL. VI. 23 MAY, 1858. 



