172 LOUIS PASTEUK. 



after it has been cooled, is passed into open wooden 

 tuns, and the working of the yeast takes place at a tem- 

 perature of about 6 Centigrade. This temperature is 

 maintained by means of floats, in the form of cones 

 or cylinders, thrown into the fermenting tuns and 

 kept filled with ice. The fermentation lasts for ten, 

 fifteen, and even twenty days. When the beer is 

 drawn off, the yeast is collected from the bottom of the 

 fermenting tuns. This kind of beer, which is some- 

 times called German beer, sometimes Strasburg beer, 

 is generally much more esteemed than the other, but 

 it requires certain expensive, or at least inconvenient, 

 conditions. There must be ice-caves, where the tem- 

 perature is maintained all the year round at a few 

 degrees only above zero. This makes it necessary to 

 have enormous piles of ice. It has been calculated that 

 for one single hectolitre of good beer, from the begin- 

 ning of the cooling of the wort until the time when it 

 is fit for sale, 100 kilogrammes of ice are required. 

 The ' low ' beer, called also biere de garde, beer for keep- 

 ing, is principally manufactured in winter, and is 

 preserved in ice-caves until the summer. 



It is not only the taste of the consumers which 

 has favoured the manufacture of beer of low fermen- 

 tation everywhere except in England ; it is also the 

 advantage this beer possesses in being much less liable 

 to deterioration than the other. By employing ice, the 

 brewer may manufacture in winter, or in the beginning 



