JOHANN CARL LEUCHS ON WINE-MAKING. 201 



wine, whicli is colored red by a tincture of litmus. A weak al- 

 kaline or nitrogenic solution is then added drop wise until the 

 red color changes into blue, the sign that the acid has been neu- 

 tralized. The more of this solution it takes, the more acid is con- 

 tained in the wine. That which is specifically the heaviest, and 

 therefore richest in sugar, has usually the least proportion of 

 acids. 



The Fermentation^ or Carbomc Acid Scale. 



This consists simply of a tube, the bore of which is marked off 

 into cubic inches, in which the carbonic acid produced in fer- 

 mentation is caught. The principle of its use is this : One grain 

 of sugar, according to Dobreiner, produces y^ cubic inch of car- 

 bonic acid. The quantity of the sugar, and consequently the 

 quality of the must, can therefore be ascertained by the quantity 

 of carbonic acid which it develops. For instance, if -^ cubic 

 inch of must gives 1-J- cubic inches of carbonic acid, IfVV grain 

 of sugar must consequently have been contained in it (7r-^ = l-nnr)- 



One grain of sugar gives, farthermore, during the fermentation, 

 xoV grains of alcohol ; or, when f^ cubic inches of carbonic acid 

 are formed, -^ grains of alcohol are at the same time produced. 

 If, therefore, -^ cubic inch of must has by fermentation develop- 

 ed 4y'^ cubic inches of carbonic acid, it contained 5 grains of 

 sugar {P:l%=6 grains), and has formed out of it 2^— (5 x 0.51 = 

 2.55) grains of alcohol. 



For this purpose serves a tube, divided into cubic inches, into 

 which the developing carbonic acid is caught. 



III. 

 MANUFACTUEING GRAPE WINE. 



General Observations. 



So many different causes influence this that hardly two casks 

 of the same sort of wine are exactly equal in all their points. 



If the wines are filled in casks or bottles after the must has 

 gone through the first fermentation, and before all the sugar has 

 been dissolved by the after fermentation and the yeast secreted 

 they will continue to ferment more or less strongly, and to devel- 

 op a great deal of carbonic acid, which may burst the casks if 

 quite filled. The gas rises in a multitude of small bubbles, spout- 

 ing up when the casks are opened, in case they withstand the 

 pressure. Such wines are called effervescent. The kind most 

 known of them is the Champagne. 



If the fermentation is allowed to go to its full end, so that all 



