2S5 FERMENTATION OF SUGAR. 



the sugar as carbonic acid, because the whole quantity is obtained 

 as oxalic acid, when sugar is treated with hypermanganate of pot- 

 ash (Gregory) ; and as oxalic acid is a lower degree of the oxi- 

 dation of carbon than carbonic acid, it is impossible to conceive 

 that the lower degree should be produced from the higher, by 

 means of one of the most powerful agents of oxidation which we 

 possess. 



It can be also proved, that the hydrogen of the sugar does not 

 exist in it in the form of alcohol, for it is converted into water 

 and a kind of carbonaceous matter, when treated with acids, 

 particularly with such as contain no oxygen ; and this manner 

 of decomposition is never suffered by a compound of alcohol. 



Sugar contains, therefore, neither alcohol nor carbonic acid, so 

 that these bodies must be produced by a different arrange- 

 ment of its atoms, and by their union with the elements of 

 water. 



In this metamorphosis of sugar, the elements of the yeast, by 

 contact with which its fermentation was effected, take no ap- 

 preciable part in the transposition of the elements of the sugar ; 

 for in the products resulting from the action, we find no compo- 

 nent part of this substance. The same sugar which in contact 

 with yeast yields alcohol and carbonic acid gives rise, when in 

 contact with putrefying white cheese, to butyric acid, hydrogen 

 being at the same time liberated. (Pelouse and Gelis.) 



We may now study the fermentation of a vegetable juice, con- 

 taining not only saccharine matter, but also such substances as 

 albumen and gluten. The juices of parsneps, beet-roots, and 

 onions, are well adapted for this purpose. When such a juice is 

 mixed with yeast at common temperature, it ferments like a solu- 

 tion. Carbonic acid gas escapes from it with effervescence, and 

 in the liquid, alcohol is found in quantity exactly corresponding 

 to that of the sugar originally contained in the juice. But such 

 a juice undergoes spontaneous decomposition at a temperature of 

 from 95° to 104° (35° — 40° C). Gases possessing an offensive 

 smell are evolved in considerable quantity, and when the liquor 

 is examined after the decomposition is completed, no alcohol can 

 be detected. The sugar has also disappeared, and with it all the 

 azotized compounds which existed in the juice previously to its 



