114 BACTERIA, YEASTS, AND MOLDS 



tation continues for a time, but rather slowly. Since the 

 vessels are dosed the carbon dioxide gas cannot escape, 

 but, accumulating in the vessel, is partly dissolved in the 

 liquid itself. The gas exerts considerable pressure inside 

 the bottle or cask, and when it is opened the expansion 

 of the gas gives rise to the popping of the corks and the 

 bubbling and frothing of the beer ; in other words, to the 

 sparkle. In beers the carbon dioxide is desired no less than 

 the alcohol, since it contributes materially to the flavor of 

 the product. In ordinary wines, however, the fermentation 

 is allowed to continue for a much longer period and the 

 gas permitted to escape; hence the alcohol content be- 

 comes high and the drink has no sparkle. 



Such fermentations form the basis of immense indus- 

 tries in other countries, and did in the United States before 

 prohibition. The present law has resulted in much more 

 home production of fermented drinks in this country than 

 ever before, especially of wines. The fermentative process, 

 however, should be given more careful control than can 

 ordinarily be managed in the home ; and such home brew 

 seldom recommends itself to any except those who crave 

 alcohol in any form. 



There is, however, a type of homemade beer which is 

 easy to make and is ordinarily too low in alcohol to be in- 

 toxicating or to come within the scope of prohibition 

 legislation. 



In previous years this was made from certain roots and 

 extracts of strongly flavored plants. For example: home 

 beers have been made from a mixture of molasses and hops 

 flavored with spruce extract; or sugar and ginger with 

 lemon for flavor; or a mixture of sugar, crushed raisins, 



