SUGAES. 51 



into another, which is effected in some instances with great 

 facility. 



Simon 1 gives the following composition of the animal 

 sugars in a crystalline form : 



Liver Sugar and Glucose, C 12 H 14 O 14 . 

 Milk Sugar, C H H w O ia . 



On exposing either of these varieties of sugar to a dry 

 heat, two atoms of water of crystallization are driven off, 

 leaving the formula for liver '"sugar, C 12 H 12 O 12 , and for milk 

 sugar, C 12 H 10 O 10 . From the relative composition of these 

 varieties of sugar, it is seen that the addition of two atoms 

 of hydrogen and oxygen, or water, to milk sugar, will trans- 

 form it into glucose. This change actually takes place in 

 digestion. The digestive fluids act also upon cane sugar 

 (C 12 H n O n ) and starch (C 12 H 10 O 10 ), transforming them into 

 glucose. 



Animal sugars are distinguished from cane sugar by 

 their different behavior in the presence of acids and alkalis. 

 Cane sugar is converted into the animal variety by boiling 

 for a few seconds with a dilute mineral acid, and is unaffected 

 by boiling with an alkali ; while the animal sugars are not 

 affected by acids, and are transformed into a dark-brown 

 substance, melassic acid, by boiling with an alkali. 



If a solution of sugar be mixed with a little fresh yeast 

 and kept for a few hours at a temperature of from 80 to 

 100 Fahr., a peculiar change takes place which is called fer- 

 mentation. The sugar is decomposed into -carbonic acid gas, 

 which rises to the top in bubbles, and alcohol, which remains 

 in the liquid. Some ferments, especially organic matters in 

 process of decomposition, when they exist in a saccharine 

 solution, have the property of inducing a change of the sugar 

 into lactic acid (C C H 6 O 6 ), giving rise to what is called the 

 lactic-acid fermentation. This process is peculiarly interest- 



1 SIMON'S Chemistry of Man, Philadelphia, 1846. 



