310 VINEGAR, CIDER, AND FRUIT-WINES. 



composition ; they are vegetable albumen, fibrin, and glue. The 

 quantities of these substances in the different musts are, on the 

 one hand, too small, and the difficulty of accurately distinguishing 

 them from each other is, on the other, so great that it is scarcely 

 possible to definitely determine the kind present in the fruit juice ; 

 most likely all three are present at the same time. 



For the preparation of wine these bodies are of importance ; 

 they furnish the material for the development of the yeast-fungus 

 during fermentation. 



Pedous substances. In the paragraph " ripening of fruits," the 

 pectous substances have been sufficiently discussed; they are 

 scarcely ever wanting in a fruit juice, but being insoluble in alco- 

 holic fluids they are entirely separated with the yeast, and hence 

 are not present in fruit-wines. 



Gum and vegetable mucilage. Our knowledge as regards gum 

 is still limited. Gum-arabic, which may be studied as a repre- 

 sentative of this class, is an exudation from certain species of 

 acacia and consists essentially of arabin. It is generally supposed 

 to be soluble in water, but on endeavoring to filter a somewhat 

 concentrated solution not a drop will be found to run off, and the 

 little which possibly may pass through the filter is by no means 

 clear. 



Closely related to gum-arabic is bassorine, the gum which 

 exudes from the cherry, plum, almond, and apricot trees. It 

 does not give a slime with water, but merely swells up to a 

 gelatinous mass. 



Wine brought in contact with the smallest quantity of gum- 

 arabic remains permanently turbid and cannot be clarified by 

 filtering or long standing. From this behavior of gum it may 

 be concluded that, though it may occur dissolved in the must, it is 

 not present in the wine. 



The various kinds of vegetable mucilage have also not yet 

 been accurately examined; it is only known that there are 

 quite a number of them. It is, however, likely that only a 

 few of them are actually soluble in water. Though the muci- 

 lage ^df certain seeds, such as linseed and quince-seed, may be 

 considered as readily soluble in water as gum-arabic, and perhaps 

 more so, because it is a perfectly clear fluid drawing threads, 



