312 VINOUS FERMENTATION. 



vegetable juice, belong to two different kinds of transformations. 

 There is reason to believe that its change to the insoluble state 

 depends upon an absorption of oxygen, for its separation in this 

 state may be effected, under certain conditions, by free exposure 

 to the air, without the presence of fermenting sugar. It is known 

 also that the juice of grapes, or vegetable juices in general, be- 

 come turbid when in contact with air, before fermentation com- 

 mences ; and this turbidity is owing to the formation of an 

 insoluble precipitate of the same nature as ferment. 



From the phenomena observed during the fermentation of wort,* 

 it is known with perfect certainty that ferment is formed from 

 gluten at the same time that the transformation of the sugar is 

 effected ; for the wort contains the azotized matter of the corn, 

 namely, gluten in the same condition as it exists in the juice of 

 grapes. The wort ferments by the addition of yeast, but after its 

 decomposition is completed, the quantity of ferment or yeast is 

 found to be thirty times greater than it originally was. 



Yeast from beer and. that from wine, examined under the mi- 

 croscope, present the same form and general appearance. They 

 are both acted on in the same manner by alkalies and by acids, 

 and possess the power of inducing fermentation anew in a solution 

 of sugar ; in short, they must be considered as identical. 



The fact that water is decomposed during the putrefaction of 

 gluten, has been completely proved. The tendency of the carbon 

 of the gluten to appropriate the oxygen of water must therefore 

 always be in action, whether the gluten is decomposed in a soluble 

 or insoluble state. These considerations, therefore, as well as 

 the circumstance which all the experiments made on this subject 

 appear to point out, that the conversion of gluten to the insoluble 

 state is the result of oxidation, lead us to conclude that the oxy- 

 gen consumed in this process is derived from the elements of 

 water, or from the sugar which contains oxygen and hydrogen in 

 the same proportion as water. At all events, the oxygen thus 

 consumed in the fermentation of wine and beer is not taken from 

 the atmosphere. 



• Wort is an infusion of malt ; it consists of the soluble parts of thi* 

 substance dissolved in water. 



