STUDIES ON FERMENTATION. 387 



§ YI. — Application of the Principles of the New Process 

 OF Brewing with the Use of Limited Quantities of 

 Air. 



We have now an idea of the quantities of ox5'gen which 

 occur, free or combined, in the actual processes of manufacture. 

 We know, moreover, that an excess of air may be injurious, 

 especially to the aroma of the beer, and to that quality which 

 consumers prize so highh^ which goes by the name of bouche. 

 It must, therefore, be important to ascertain whether in existing 

 processes the proportion of active oxygen may not be excessive. 



The best practical means of determining this would consist 

 in comparing the products of different processes with progres- 

 sively increasing access of air, starting from none at all, as in 

 the ease of cooling in the presence of an atmosphere of carbonic 

 acid gas. The following arrangement (Fig. 85) permits us to 

 realize these conditions : — 



The wort brought to a temperature between 75° and 80° C. 

 (167° and 176° F.) in the double-bottomed vessel C, passes by 

 the tube a h into a refrigerator, such as Bandelet's, for example, 

 but acting in an inverse manner to the ordinary mode of using 

 Baudelot's ; that is to say, the wort is made to circulate inside 

 the tubes, whilst the cold water plays on the outside.* The 



* It is evident that this arrangement may be modified in many 

 ways. Any of the ordinary worms, or, generally speaking, any of the 

 more modern refrigerators invented during the last few years, may be 

 adopted. The only point that is of importance is the preservation of the 

 purity of the wort during cooling. 



The Baudelot refrigerator is extensively adopted in France ; for this 

 reason we used it in our experiments at Tantonville. We might equally 

 well, by enclosing the worm in a casing of sheet iron or tinned copper, 

 pass our wort over the exterior of the tubes, the cold water passing 

 through them. The wort would cool quicker in this way than with the 

 arrangement described in the text, and if we arrange to admit only pure 

 air into the case, always under conditions of purity. The aeration, 

 moreover, could be made as much as we wished. 



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