260 GRAPE CULTURE AND WINE-MAKING. 



Sirups of a darker color than light yellow can only be used in 

 the fabrication of red wines. 



The Acids of the Must. 



Those contained in the grape-juice are part/ree, part combined 

 with earths and alkalies, with which they form bitter as well as 

 neutral salts. Only the free and the hitter salts can be detected 

 by the taste, and proved in their total quantity in the wine. 



The acid parts, besides deciding the palatable taste of the wine 

 present in proper proportions, also determine and influence, ac- 

 cording to general belief, the existence of many different combi- 

 nations, and by these the formation of the aroma (flavor). 



To prove this supposition, it is said by many that principally 

 those wines that contain a great deal of acids develop a rich bou- 

 quet^ while this is almost entirely wanting in the southern wines 

 holding less acids. It seems, however, that in asserting this, the 

 bouquet is confounded with the wine-smell appertaining to all the 

 wines of a larger acid content than the southern have. In this 

 connection, also, that part of .acids can only be considered as con- 

 ditioning the development of the wine-smell that is- proper to those 

 wines in the best season, because otherwise the over-acid wines 

 of inferior seasons would have to show the strongest wine-smell. 



Hence follow the consequences of this in favor of a reduction 

 of the contents of acids of a more than ordinary sour must upon 

 them in good seasons, the more properly, as we know that for a 

 long time various articles, as chalk, lime, potassa, etc., have been 

 used to reduce those acids. Ilowever, the real relation of these 

 free acids remained a secret until that eminent chemist, Dr. Ltj- 

 DERSDORF, Supplied this want, and gave thereby a firm and secure 

 foundation to the art of wine fabrication. He recognized the fact 

 that the most esteemed wines (in other respects of equally good 

 qualities) were more valued by their quantity of medium contents 

 of acid than that of alcohol. This induced him to examine in the 

 year 1841 about eighteen different sorts of wines of the vintage 

 of 1834, and to publish those results in Erdmann^s Journal for 

 Chemistry^ which may be seen in the table on the next page. 



It will not be amiss to add a few remarks here for such as have 

 no farther knowledge of the science of chemistry. ^ ■ 



Acids and alkalies are characterized by their capacity of neu- 

 tralizing each other's qualities. For instance, acids change the 

 blue color of litmus tincture into red; now to this red fluid add 

 a sufficient quantity of an alkali, and the blue color will be re- 

 stored, the acid being neutralized. The point at which this takes 

 place is called the satiating point. The greater the quantity of 

 acid (say vinegar or wine) which had been added to the litmus 

 tincture in order to recover it, the more alkali will be required to 

 change the color back to blue. Now, as a certain quantity of al- 

 kali is required to neutralize a definite amount of a particular 



