258 THE FLOATING-MATTER OF THE AIR. 



process, called Jiigh fermentation^ is far more handy, 

 expeditious, and cheap. In high fermentation eight 

 days suffice for the production of beer ; in low fermenta- 

 tion, ten, fifteen, even twenty days are found necessary. 

 Vast quantities of ice, moreover, are consumed in the 

 process of low fermentation. In the single brewery of 

 Dreher, of Vienna, a hundred million pounds of ice are 

 consumed annually in cooling the wort and beer. Not- 

 withstanding these obvious and weighty drawbacks, the 

 low fermentation is rapidly displacing the high upon 

 the Continent. Here are some statistics which show the 

 number of breweries of both kinds existing in Bohemia 

 in 1860, 1865, and 1870:— 



Thus in ten years the number of high-fermentation 

 breweries fell from 281 to 18, while the number of low- 

 fermentation breweries rose from 135 to 831. The sole 

 reason for this vast change — a change which involves a 

 great expenditure of time, labour, and money — is the 

 additional command which it gives the brewer over the 

 fortuitous ferments of disease. These ferments, which, 

 it is to be remembered, are living organisms, have their 

 activity suspended by temperatures below 10° C, and 

 as long as they are reduced to torpor the beer remains 

 untainted either by acidity or putrefaction. The beer 

 of low fermentation is brewed in winter, and kept in 

 cool cellars ; the brewer being thus enabled to dispose 

 of it at his leisure, instead of forcing its consumption 

 to avoid the loss involved in its alteration if kept too 

 long. Hops, it may be remarked, act to some extent 

 as an antiseptic to beer. The essential oil of the hop 

 is bactericidal ; hence the strong impregnation with hop 

 juice of all beer intended for exportation. 



