320 FERMENTATION OF BEER 



several stages. The first stage is the conversion of the gluten 

 into insoluble ferment in the interior of the liquid, and as the 

 transformation of the sugar goes on at the same time, carbonic 

 acid and yeast are simultaneously disengaged. It is known with 

 certainty, that this formation of yeast depends upon oxygen 

 being appropriated by the gluten in the act of decomposition ; 

 but it has not been sufficiently shown, whether this oxygen is 

 derived from the water, from the sugar, or from the gluten 

 itself; whether it combines directly with the gluten, or merely 

 with its hydrogen, so as to form water. For the purpose of 

 obtaining a definite idea of the process, we may designate the 

 first change as the stage of oxidation. This oxidation of the 

 gluten then, and the transposition of the atoms of the sugar into 

 alcohol and carbonic acid, are necessarily attendant on each 

 other, so that if the one is arrested the other must also cease. 



Now, the yeast which rises to the surface of me liquid is not 

 the product of a complete decomposition, but is oxidized gluten 

 still capable of undergoing a new traps formation by the transpo- 

 sition of its constituent elements. By virtue of this condition it 

 lias the power to excite fermentation in a solution of sugar ; and 

 if the gluten be also present, the decomposing sugar induces its 

 conversion into fresh yeast, so that, in a certain sense, the yeast 

 appears to reproduce itself. 



Yeast of this kind is oxidized gluten in a state of putrefaction, 

 and by virtue of this state it induces a similar transformation in 

 the elements of the sugar. 



The yeast formed during the fermentation of Bavarian beer 

 is oxidized gluten in a state of decay. The process of decompo- 

 sition which its constituents are suffering, gives rise to a very 

 protracted putrefaction ( fer.ncntatio-n) in the sugar. The inten- 

 sity of the action is diminished in so great a degree, that the 

 gluten which the fluid still holds in solution takes no part in it ; 

 the sugar in fermentation does not excite a similar state in the 

 gluten. 



But the contact of the already decaying and precipitated 

 gluten or yeast, causes the eremacausis of the gluten dissolved in 

 the wort ; oxygen gas is absorbed from the air, and all the gluter 

 in solution is deposited as yeast. 



