THE BAVARIAN PROCESS. 307 



ment of fermentation exercises upon the quality of 

 beer is well known in several of the German states. 

 In the grand-duchy of Hesse, for example, a con- 

 siderable premium is offered for the preparation of 

 beer, according to the Bavarian method ; and the 

 premium is to be adjudged to any one who can 

 prove that the beer brewed by him has lain for six 

 months in the store-vats without becoming acid. 

 Hundreds of casks of beer became changed to 

 vinegar before an empirical knowledge of those 

 conditions was obtained, the influence of which is 

 rendered intelligible by the theory. 



Neither alcohol alone, nor hops, nor indeed both 

 together, preserve beer from becoming acid. The 

 better kinds of ale and porter in England are pro- 

 tected from acidity, but at the loss of the interest 

 of an immense capital. They are placed in large 

 closed wooden vessels, the surfaces of which are 

 covered with sand. In these they are allowed to 

 lie for several years, so that they are treated in a 

 manner exactly similar to wine during its ripening. 



A gentle diffusion of air takes place through the 

 pores of the wood, but the quantity of azotised 

 substances being very great in proportion to the 

 oxygen which enters, they consume it, and prevent 

 its union with the alcohol. But the beer treated 

 in this way does not keep for two months without 

 acidifying, if it be placed in smaller vessels, to 

 which free access of the air is permitted. 



x2 



