354 FERMENTATION OF BEER. 



In the same manner the soluble gluten may be con- 

 sidered a compound of hydrogen, which becomes 

 ferment by losing a certain quantity of this element 

 when exposed to the action of the oxygen of the air 

 under favorable circumstances. At all events, it is 

 certain that oxygen is the cause of the insoluble con- 

 dition of gluten ; for yeast is not deposited on keep- 

 ing wine, or during the fermentation of Bavarian 

 beer, unless oxygen has access to the fluid. 



Now, whatever be the form in which the oxygen 

 unites with the gluten, — whether it combines di- 

 rectly with it or extracts a portion of its hydrogen, 

 forming water, — the products formed in the interior 

 of the liquid, in consequence of the conversion of 

 the gluten into ferment, will still be the same. Let 

 us suppose that gluten is a compound of another 

 substance with hydrogen, then this hydrogen must 

 be removed during the ordinary fermentation of must 

 and wort, by combining with oxygen, exactly as in 

 the conversion of alcohol into aldehyde* by erema- 

 causis. 



In both cases the atmosphere is excluded ; the 

 oxygen cannot, then, be derived from the air, neither 

 can it be supplied by the elements of water, for it is 

 impossible to suppose, that the oxygen will separate 

 from the hydrogen of water, for the purpose of unit- 

 ing with the hydrogen of gluten, in order again to 

 form water. The oxygen, must, therefore, be ob- 

 tained from the elements of sugar, a portion of which 

 substance must, in order to the formation of ferment, 

 undergo a different decomposition from that which 

 produces alcohol. Hence a certain part of the sugar 

 will not be converted into carbonic acid and alcohol, 

 but will yield other products containing less oxygen 

 than sugar itself contains. These products, as has 

 already been mentioned, are the cause of the great 



* A liquid having a peculiar ethereal smell, and obtained by passing 

 the vapor of ether through a large glass tube heated to redness, and by 

 other processes. It consists of carbon 4, hydrogen 4, oxygen 2. Its 

 name is from the Latin, alcohol dehydratus. 



