666 SUGARS 



in the sun, yellow dark-brown crystals of raw sugar are 

 formed, and there drains away a variable quantity of 

 brown uncrystallised molasses. A hundredweight of raw 

 sugar yields about 80 pounds refined sugar and 16 pounds 

 treacle. 



There are two classes of sugars (1) the Sucroses or Sac- 

 charoses, which, when dry, have the formula C 12 H 22 O n , 

 and (2) the Hexoses, with the formula C 6 H 12 6 . 



Sucrose, saccharose, or cane sugar (C 12 H 22 O n ), like sulphur 

 and arsenious acid, has an amorphous and a crystalline 

 form, its crystals are monoclinic prisms ; specific gravity 

 1/606 ; it phosphoresces in the dark, and is dextro-rotatory. 

 It is hydroscopic, soluble in one-third of its weight of water 

 at 60 Fahr., but insoluble in absolute alcohol. A strong 

 solution, evaporated and heated to 320 Fahr., fuses, and 

 the vitreous mass can be moulded into barley-sugar. 

 Between 356 and 374 Fahr. sucrose parts with two 

 molecules of water, loses its sweet taste, acquires a dark 

 colour, and becomes caramel, which is used by confectioners 

 and distillers as a colouring agent. 



Sucrose in plants is gradually built up from the simpler 

 hexoses (C 6 H 12 6 ), and, conversely, when acted on by dilute 

 acids or by ferments, such as diastase or yeast, it is again 

 converted into glucose and fructose. Sucrose undergoes 

 this change before it yields alcohol. 



Maltose (C 12 H 22 11 .H 2 0) is prepared by grinding starch 

 with water, warming it until it gelatinises, and heating with 

 crushed malt, the diastase of which sets up fermentation, 

 causing three molecules of starch to appropriate one of 

 water, and yield one molecule of maltose and one of dextrin. 

 Maltose is also formed during the digestion of starch by the 

 ferments of the salivary, intestinal, and pancreatic juices. 

 It is soluble and readily fermented. 



Lactose, or milk sugar (C 12 H 22 11? H 2 0), is prepared by 

 evaporating whey to a syrup, and crystallising. It occurs 

 in translucent, greyish-white, hard cylindrical masses of 

 rhombic prisms. It is gritty, and, being less soluble, is not 

 so sweet as the vegetable sugars. It is not directly fer- 

 mentable. Lactose is a very active diuretic, but in practice 

 milk or whey is preferred. 



