24 SORGHUM. 



of 75°C. (177°F.), bad only 5.49 grams, of the sugar inverted, or 9.15 

 per cent of the amount ; so that, in ordinary work, the inversion of 

 sugar by heat alone may be regarded as very slight. 



In the presence of a slight excess of lime, it has been found that a 

 solution of cane sugar remains unchanged, even after prolonged boil- 

 ing for thirty-six hours. The practical importance of this fact is obvi- 

 ous to the sugar manufacturer, since, by proper defecation with lime, 

 the acids present in the saccharine juices of plants are neutralized and 

 rendered inert. 



3. Lactose, or milk sugar, C,.,H,,20i,. 



This sugar is that which gives to milk its sweet taste. 



Lactose, although having the same composition as cane sugar,, differs 

 from it very greatly in all its properties, in crystalline form, degree of 

 solubility, and sweetness, and in its rotatory power, which, though 

 right-handed as is that of cane sugar, is far less in degree — the relative 

 degrees of rotatory power of the four sugars mentioned being as follows: 



Cane Susar, right-lianfled 73°8 



Milk " " " 59°3 



Dextrose, " " 5fi° 



Laevulose, left " 106'' at 14° C 



53° at 90° C 



Lactose, also, in ordinary fermentation, produces Lactic Acid instead 

 of glucose. The formula representing the results of the fermentation, 

 being : 



Lactose -|- Water = Lactic Acid. 



c„H,,o„ -t H,o ^ 4 an A 



The one molecule of lactose taking up one molecule of water and 

 being then broken up into four molecules of lactic acid ; this result 

 constituting what is known as the souring of milk. 



The relative solubilities of these several sugars in cold water, are 

 as follows : 



1 part Cane Sugar in % Its weight of water. 



1 •• Glucose " IK 



1 " Lactose " 5 times its weight of water. 



Cane sugar is readily obtained in crystals by the evaporation of its 

 solution in water, as in the familiar form of the so-called granulated 

 sugar, which may be seen to be composed of well defined crystals, also 

 in the well known form of rock candy, in which crystals an inch in 

 diameter are often found. 



Glucose also crystallizes both in its anhydrous form, and also in 

 combination with water. The crystals of glucose, however, are gen- 

 erally a collection of minute needles clustered into granular masses, or, 

 if the solution is concentrated, uniting to form a semi-solid mass ; as 



