The Chemistry of Wint 



In preserving 

 fruitS; for instance cherries, while 

 thej are put in a glassvessel in raw 

 condition and the vessel closed up 

 with a piece of bladder being ex- 

 posed for about half an hour to the 

 heat of boiling water, the fungus- 

 buds upon the cherries and in the 

 vessel are destroyed ; and the blad- 

 der afterwards works the same way 

 as the wadding, preventing the ac- 

 cess of the germs from the atmosphere. 

 The same eflect will be produced by 

 covering a fermentable or deca^-ing 

 liquid with oil or tallow. And also, 

 b}^ preventing the access, the for- 

 ming of the infusory worm will he 

 guarded against, whose germs im- 

 pregnate the atmosphere and exist 

 everywhere. 



Besides oxygen, which they find 

 nearly everywhere, the yeast-cells 

 require nitrogen for their deve- 

 lopment, which is contained in the 

 gluten of most of the plants. If then, 

 fermenting can be brought forth only 

 by formation of yeast, that fermen- 

 tation will last no longer, than until 

 the nitrogen of the liquid has been 

 consumed, provided the air has no 

 free access, so as to enable the yeast- 

 cells to receive nitrogen from the at- 

 mosphere, thereby remaining on the 

 surface of the liquid in the form of 

 mould. 



If fermentation depended mereh' 

 on the solution of the existing sugar 

 without regard to the presence of nit- 

 rogen, there would be no ready made 

 wines containing sugar. The very 



THE CHEMISTEY OF WINE. 



Bj Chas. H. Flings, 

 (continued.) 



different kinds of richness of sugar enables the juice of 



grape to full}' perform fermentation. 

 After fermentation, the sugar 3'et exis- 

 ting will not be dissolved any more, 

 except in the case above mentioned, 

 where the spirituous fermentation, by 

 way of access of aii*, is transfornied 

 into acid or fermentation of vinegar. 

 From these reasons wines of heavj' 

 bodyaremore durable than light ones, 

 the first named, being free of gluten and 

 albumen, sometimes to a high degree 

 contained in mild wines not fermen- 

 ted to the full extent. In the latter 

 case the contents of sugar in the juice 

 of grape are not sufiicient, having 

 been transformed into alcohol and 

 carbonic acid before the complete con- 

 sumption of nitrogen substances. 

 Some wines even incline to change 

 into acitous fermentation. 



But the fermenting capacit}^ of 

 sugar has also its culminating point. 

 If the juice of the grape contains more 

 than 25 per cent of sugar, the spiri- 

 tous fermentation ends as soon as 

 12 — 13 per cent of alcohol have for- 

 med, according to the quantity of 

 sugar above stated. The balance of 

 the sugar remains imdissolved ; never- 

 theless, the nitrogen and 5'east-for- 

 ming contents may prevail in such a 

 degree, as to produce a sediment in 

 the wine at any change of place or 

 temperature, or whenever air is ad- 

 mitted, although they may contain 

 undissolved sugar. 



In all cases however, where Avinc is 

 changing, either for better or worse, 

 the germs of fungus perform an 



