268 GRAPE CULTURE AND WINE-MAKING. 



out the darker the less acids it holds, because these change the 

 deep reddish-hlue into red. 



A not too large addition of water (with a corresponding of sug- 

 ar) will therefore not reduce the color of the wine, but make it 

 frequently appear darker. 



By frequent connection with the air the coloring matter oxy- 

 dizcs, turns brown-red, and separates itself by-and-by from the 

 wine. The filling of red wines from one cask into another ought, 

 therefore, always to be attended with great care. By adding a 

 little cream of tartar, the change of color may, however, be stop- 

 ped, or itself renewed. 



The green color of the white or yellow grapes is formed by a 

 coloring matter, contained as well in the juice as skin, called 

 "leaf green," or " chlorophill." The reason why, out of green 

 must, wine of more or less light or dark yellow color is produced, 

 lies in the larger or smaller contents of lime of the soil that those 

 grapes grew on. 



The Nitrogenic Comhinaiions and the Ferment. 



These (vegetable albumen, etc.), perfectly dissolved in the must 

 as well as wine, attain, under particular circumstances, the faculty 

 of originating the fermentation by whose action (and this is about 

 all we know) the must changes into wine. A great many of the 

 yeast stuffs, not being consumed, remain, however, and our white 

 wines especially appear to be apt to retain them in so much, often 

 that, even after being kept for years, they will work again, and 

 form anew a kind of fermentation. The red wines retain consid- 

 erably less. The yeast stuff remaining in the wine effects, after 

 all the sugar is dissolved, the alcohol in the same manner as the 

 former, so that, as this by combination with oxygen forms the 

 yeast, the alcohol with oxygen forms the acid of vinegar. 



The Flavor Matters. 



Besides the particular agreeable ivine smell shared by all grape 

 wines, some of them have still another flavor, similar to that of 

 the grape blossom, generally called " aroma, jloioer, bouquet.'''' It 

 only develops itself during the fermentation, and the more and 

 stronger the richer the grapes were in sugar. It is probable that 

 the alcohol of the wine effects greatly the so-called bouquet stuff 

 (though this itself is as great a secret), as we know the more sug- 

 ar in the must the more alcohol is formed. 



The Extractive Matters. 



These comprise all those parts of the wine that are not vola- 

 tile ; that is to say, the remaining parts of the wine after all oth- 

 ers have evaporated, as water, alcohol, acid of vinegar, etc. The 

 value of the wine is not affected by them, or only to a very small 

 degree. 



