THE CHEMISTRY OF SUGAR. 505 



again, and the angle through which it has been moved is read on a 

 divided circle and vernier. 



Since the rotation is less for the sodium-ray than for the transition 

 tint, the two are distinguished by different symbols. For the former 

 the symbol [a] D is used, and for the latter [a] or [a]j. The one-color 

 saccharimeter is especially to be recommended for those who may be 

 subject to any degree of color-blindness. A discussion of the optical 

 principles involved in circular polarization would be out of place here. 



Fermentation is a peculiar decomposition which sugars suffer un- 

 der the influence of a nitrogeneous germ called the " ferment." 



Cane-sugar, under the influence of a mucous sporule, undergoes 

 "mucous fermentation," and is converted into a gum and a kind of 

 sugar called "mannite." Neither acid nor alcohol is produced by this 

 process. 



Lactic fermentation takes place under the influence of an organ- 

 ism called penicilium glaucum. The chief product of this fermenta- 

 tive is lactic acid. In the case of a dextrose it may be represented by 

 the following equation : 



Dextrose. Lactic Acid. 



C 6 H n O,=2C,H e O,. 



Milk-sugar undergoes this fermentation most readily, first absorb- 

 ing a molecule of water and then breaking up into four molecules of 

 lactic acid. If the process is allowed to go on, the lactic acid will 

 break up into butyric acid, carbonic dioxide, and hydrogen. If the 

 Torula aceti take the place of the germ named above, cane-sugar 

 especially will yield acetic instead of lactic acid. 



The vinous is by far the most important of the fermentations to 

 which sugars are subjected. 



Ordinary yeast is the nitrogenous body which seems best suited to 

 develop this change. 



Cane-sugar, before undergoing vinous fermentation, absorbs a mol- 

 ecule of water and is changed by an active principle of the yeast into 

 invert-sugar. The chief products of vinous fermentation are alcohol 

 and carbonic dioxide. Less important products are succinic acid, 

 glycerine, cellulose, and fat. 



All the sugar, with the exception of about four per cent., is con- 

 verted into the two products first named. By an equation, the process 

 may be represented as follows : 



Sucrose. Water. Alcohol. Carbonic dioxide. 



C 12 H a2 O u + H a O=4 C 2 H 6 + 4 CO,. 



Thcpeculiar fungus which is most active in the vinous fermenta- 

 tion is saccharomyces cerevisice / but there is much about the process 

 which is yet obscure. 



In the conversion of starch into sugar by diastase or acids, and the 

 conversion of sugar into alcohol by fermentation, we have the ratio- 

 nale of that vast industry carried on by distillers and brewers. If the 



