72 STATE POMOLOGICAL SOCIETY. 



Strikes one as founded upon the principle which cures the bite of a 

 dog hy application of its own hair. The process of fermentation, 

 by which a solution of sugar and acid is converted into alcohol, or, 

 if carried still farther, from the alcohol into vinegar, has been the 

 subject of most acrimonious debate among the foremost chemists of 

 the world. Up to 1872 the chemical theory upheld by Liebig, the 

 German chemist, was accepted as definite and satisfactory. This 

 held that the expressed grape juice, having been set aside in large 

 vats, the vegetable albumen of the juice absorbing oxygen from the 

 air, decomposed, and in that state became a ferment to the sugar, 

 breaking it up chemically into alcohol and carbonic acid. This has 

 been shown to be true so far as decomposition of the sugar is con- 

 cerned, but the cause of the process has been demonstrated to be 

 something entirely different. 



It was found by Pasteur, the eminent French scientist, that the 

 decomposing process whereby sugar is destroyed and alcohol results, 

 is due to the presence of a microscopic vegetable organism, and thus 

 has arisen the physiological theory. This fungus is always present 

 upon the outside of fruit, and after the pulp is crushed and the juice 

 expressed, is of course mingled with it, then the fungus must have 

 oxygen, and finding this in the sugar it seizes upon it, chemically 

 breaking up the sugar and changing it to alcohol and carbonic acid 

 gas, the latter rising to the surface in bubbles, a process we have all 

 observed in the so-called working of cider. Every liquid capable 

 of fermenting has its own peculiar species of fungus, named accord- 

 ingly. 



Wines and cider of course owe their useful properties to the alco- 

 hol which they contain, the percentage varying according to the 

 amount of sugar present in the juice. Wines which have in fer- 

 menting used up nearly all the sugar contain the most, from 19 to 

 25 per cent and from the lack of sugar are called dry wines ; they 

 are strong, and like port and sherry neither sweet nor sour. If on 

 the other hand the ferment be scanty and only a small proportion of 

 the sugar be transformed, the result is a sweet or light wine. If 

 the wine be bottled before fermentation is complete, the gas will not 

 all escape, but will impregnate the wine, making it effervescent and 

 sparkling like champagne. So called rough wines owe their harsh 

 taste to tannic acid derived from the skins and vegetable part of the 

 pulp. The acidity of wine is due to carbonic acid or tartar. 



