BY-PRODUCTS 



355 



the vacuum produced by the contraction of the juice on cooling, by 

 filtering the air through cotton. The best treatment for sterilizing 

 in glass consists in heating the cider in the jars for an hour at 

 149 degrees F. or half an hour at 158 degrees. 



Champagne cider. Champagne cider is a clear, sparkling fluid 

 that is considered delicious by some people. It is an intensive 

 product derived from cider by the process of filtering the apple 

 juice through a large body of clean, sharp sand, and then allow- 

 ing the product to age in bottles until it has the correct flavor. 



Fig. 159. A large, well-equipped vines 

 St.Jo.u-f/, J 



and preserving 

 it Grower) 



factory. (Courtesy of 



Vinegar. For pure cider vinegar no mature apples are con- 

 sidered too poor. Vinegar-making in the ordinary way — by allow- 

 ing the cider to ferment at will in casks without controlling the 

 surrounding conditions — is not considered a profitable business. 

 By regulating the temperature and adding mother of vinegar and 

 cultures of acetic-acid ferment, fairly good vinegar may be made, 

 although the process is both slow and wasteful. The processes 

 of fermentation can be greatly hastened by the addition of equal 

 parts of fermented cider and old vinegar, but this will require a 

 large stock of old vinegar. 



A very good vinegar can be made by using a vinegar generator, 

 in which the cider passes slowly through a mass of shavings and 



