244 Alcoholic Fermentation in Cider. [july, 



fresh juice in the manner previously pointed out. As they 

 multiply, they produce the substance which acts on the sugar, 

 breaking it up and thus reducing the sweetness, while bubbles 

 ■of carbonic acid are given off, causing in the early stages of 

 fermentation a froth to form on the surface of the liquid. At 

 the same time, an increasing amount of alcohol is formed. Juice 

 in this condition is commonly spoken of as " working." It 

 increases in cloudiness considerably at this period, this being 

 due to the large numbers of yeast plants which arc formed and 

 held in suspension in the juice. As fermentation proceeds 

 many of the yeast plants become worn out and sink to the 

 bottom of the vessel containing the juice, forming the lees. 



Fermentation continues under favourable conditions until the 

 whole of the sugar is destroyed. When it ceases the yeast 

 plants sink to the bottom with the exception of a few which 

 rise to the surface of the cider and form there a thin white 

 layer, which is termed the " flowers." To avoid the formation 

 of this layer, which is exceedingly troublesome in practice on 

 account of its breaking up when the cider is disturbed, thus 

 producing turbidity, casks of mature cider should always be 

 filled and kept filled to the bung-hole, so that no considerable 

 surface may be exposed, on which the " flowers " could form. 



In typical alcoholic fermentation, sugar is invariably split up 

 in such a way that lOO parts of sugar yield approximately 50 

 parts of alcohol. The amount of alcohol which has been formed 

 in the cider at any given point of the fermentation can be 

 roughly determined as follows : — The decrease of 4 points in 

 specific gravity denotes that approximately i per cent, of sugar 

 has been destroyed, which corresponds to the production of 

 ^ per cent, of alcohol. Thus, if a cider decreased from 1,050 to 

 1,022 (a- drop of 28 points) approximately 7 per cent, of sugar 

 has been lost, and per cent, of alcohol formed. 



In addition to the formation of alcohol and carbonic acid gas 

 during the course of fermentation, it has been mentioned above 

 that small quantities of other substances are also formed. Chief 

 of these is glycerine. This substance is of service in aiding to 

 give body to the fermented liquor. Other important substances 

 also formed are various acids, which combine with alcohol 

 during the maturing of the cider to form what are called ethers. 



