29 



The writer can not refrain from observing tiiat apparently the 

 French attach entireh' too slight importance to the acid content of 

 cider fruits. French apple must sometimes turns black as ink in the 

 presence of air because of rapid oxidation of the tannin; yet it is easily 

 shown that a higher acid content will prevent this. From some state- 

 ments made it would appear that the}' consider i».l to <>.2 per cent of 

 acid sufficient. 



The Germans rank the chemical constituents in importance as fol- 

 lows: (1) sugar. (2) acids, and (3) tannin. They pay practicallv no 

 attention to determining mucilaginous substances. Their ai)ples are 

 so difierent in character (as will be seen in later discussion) that these 

 constituent elements may not be strongly developed in them. They 

 also claim that nitrogenous and mineral compounds are important as 

 nourishment for the veast organisms. The acid content is considered 

 important in German}-, and at Geisenheim the i)ercentage of acid 

 demanded is 0.6 to 0.8 per cent. While they insist upon the import- 

 ance of tannin, thev do not rate it so highly as the French. 



No English student of the subject appears to have discussed these 

 points from an original standpoint. However. Thomas Andrew 

 Knight was the first to call attention to the value of the densimeter as 

 an instrument to test the quality of must. 



In the United States we have no technical literature of any moment 

 covering this subject. It appears that Americans have proceeded on 

 the idea that the sugars are the only substance of prime importance in 

 an apple must. Tannin appears to l)e regarded as ol)jectional»le. Acid 

 is apparently regarded as an element which it is necessary to eliminate 

 as far as possible. The character of our fruits may have had something 

 to do with this, but it is rare that our fruits show too nuu'h acid, and 

 it is more to be noted that they seldom or never show enough of the 

 ver}' important element, tannin. 



Sugar content of the fruit.— Duv'xw^ the process of fermentation 

 cane sugar and possibly some of the pectose bodies are converted into 

 fermentable sugars, and practically the total sugar content of the apple 

 is thus rendered subject to the breaking down process called fermen- 

 tation. Pasteur's statement of the products resulting from the fer- 

 mentation of fruit sugars per 100 parts is as follows: 



Per cent. 



Carbon tlioxid gas (CO,) ■*t>- 67 



Alcohol : - -t^- ■*<' 



Glycerin ^--^ 



Succinic acid ^- • -^^ 



Matter consumed l)y ferment organisms 1- 03 



While this statement is now disputed in some particulars, it is used 

 here to indicate the probable results which may be expected from 

 complete fermentation of the sugar content of any fruit juice. It is, 

 then, from the sugars that all the alcohol is derived, and also the car 



