STUDIES ON BEER 171 



a light white froth, the wort is transferred to a 

 series of small barrels, which are placed in cellars 

 or store-rooms, kept at a temperature of from 18 

 to 20 Centigrade. The activity of the fermentation 

 soon causes a foam to rise, which becomes more 

 and more thick and viscous. This is owing to the 

 abundance of yeast which it contains. This yeast, 

 collected in a large trough placed under the casks, 

 is gathered up for future operations. The fermenta- 

 tion lasts for three or four days, then the beer is 

 made and has become clear ; the bungs are fixed 

 in the barrels, and they are sent direct to the retail 

 dealer or to the consumer. During the transit, a 

 certain quantity of yeast, fallen^ to the bottom of the 

 casks, thickens the beer, but a few days of repose suffice 

 to make it again clear and fit to drink, or to be bottled. 



This system of ' high ' fermentation (so called be- 

 cause it begins at a temperature of 18 to 20, and is 

 raised one or two degrees higher by the act of fer- 

 mentation itself) is very commonly practised in the 

 north of France, and to a greater extent in the 

 breweries of England. Ale, pale ale, bitter beer, are 

 all beers from high fermentation. 



The ' low ' fermentation, which is almost exclusively 

 employed in Germany, and which is spreading more 

 and more in France, consists in a slow fermentation, 

 at low temperature, during which the yeast settles 

 at the bottom of the tubs and casks. The wort, 



