140 AMOUNT OF ALCOHOL IN WINE. 





of any strength that may be wished. When a cer- 

 tain amount of alcohol has been produced, the further 

 activity of the ferment is hindered by it even when 

 an excess of sugar is still present. 



This is the case with wines which contain more 

 than 20 per cent, by volume of pure or absolute 

 alcohol, that is to say, when the liquid has become too 

 rich in alcohol, so that the fermenting matters co- 

 agulate, and become insoluble, and therefore inert. 

 Experience teaches us, therefore, that if the amount 

 of alcohol has during fermentation fully reached to 20 

 per cent, by volume, this may be considered as a maxi- 

 mum, after which fermentation is impossible. All 

 sugar which is still left remains undecomposed, since 

 the ferment has lost the power of exciting fermen- 

 tation in the strong alcoholic liquid. 



There are also substances in wine which oppose 

 fermentation, and these, even when sugar still 

 exists, may prevent a portion of the albumen from 

 being converted into ferment, and acting as such. 

 Albuminous matter and sugar are therefore to be 

 found in all wines. The substances which principally 

 oppose fermentation are acids, and the tartrate 

 and malate of potash, when present in excess. 

 If, for instance, the grape juice contains too much 

 cream of tartar, this will hinder fermentation by ren- 

 dering a portion of albuminous matter inert, and thus 

 causing some of the sugar to remain undecomposed. 

 A certain quantity of acid or super-salts is of use ; too 



