YEAST OR FERMENT. 315 



in considerable quantity, and when the liquor is ex- 

 amined after the decomposition is completed, no al- 

 cohol can be detected. The sugar has also disap- 

 peared, and with it all the azotized compounds which 

 existed in the juice previously to its fermentation. 

 Both were decomposed at the same time ; the nitro- 

 gen of the azotized compounds remains in the liquid 

 as ammonia, and, in addition to it, there are three 

 new products, formed from the component parts of 

 the juice. One of these is lactic acid, the slightly 

 volatile compound found in the animal organism ; 

 the other is the crystalline body, which forms the 

 principal constituent of manna; and the third is a 

 mass resembling gum-arabic, which forms a thick 

 viscous solution with water. These three products 

 weigh more than the sugar contained in the juice, 

 even without calculating the weight of the gaseous 

 products. Hence, they are not produced from the 

 elements of the sugar alone. None of these three 

 substances could be detected in the juice before fer- 

 mentation. They must, therefore, have been formed 

 by the interchange of the elements of the sugar with 

 those of the foreign substances also present. It is 

 this mixed transformation of two or more compounds 

 which receives the special name of putrefaction. 



YEAST OR FERMENT. 



When attention is directed to the condition of 

 those substances, which possess the power of induc- 

 ing fermentation and putrefaction in other bodies, 

 evidences are found in their general characters, and 

 in the manner in which they combine, that they all 

 are bodies, the atoms of which are in the act of 

 transposition. 



The characters of the remarkable matter, which is 

 deposited in an insoluble state during the fermenta- 

 tion of beer, wine, and vegetable juices, may first be 

 studied. 



