250 FERMENTATION OF SUGAR. 



Sugar contains, therefore, neither alcohol nor 

 carbonic acid, so that these bodies must be pro- 

 duced by a different arrangement of its atoms, and 

 by theirninion with the elements of water. 



In this metamorphosis of the sugar, the elements 

 of the yeast, by contact with which its fermentation 

 was effected, take no appreciable part in the trans- 

 position of the elements of the sugar ; for in the 

 products resulting from the action, we find no 

 component part of this substance. 



We may now study the fermentation of a vege- 

 table juice, which contains not only saccharine 

 matter, but also such substances as albumen and 

 gluten. The juices of parsnips, beet-roots, and 

 onions, are well adapted for this purpose. When 

 such a juice is mixed with yeast at common tem- 

 peratures, it ferments like a solution of sugar. Car- 

 bonic acid gas escapes from it with effervescence, 

 and in the liquid, alcohol is found in quantity ex- 

 actly corresponding to that of the sugar originally 

 contained in the juice. But such a juice under- 

 goes spontaneous decomposition at a temperature 

 of from 95 to 104 (35 40 C.). Gases possessing 

 an offensive smell are evolved in considerable quan- 

 tity, and when the liquor is examined after the de- 

 composition is completed, no alcohol can be de- 

 tected. The sugar has also disappeared, and with 

 it all the azotised compounds which existed in the 

 juice previously to its fermentation. Both were 

 decomposed at the same time ; the nitrogen of the 

 azotised compounds remains in the liquid as am- 



