SUGAR PLANTS 83 



is as a filtering material for the clearing of the 

 liquid sugar. 



Vacuum pans rarefy the air so that the contents 

 boil at a low temperature, which is the only way to 

 keep all the sucrose in the chemical state to crys- 

 tallize when the proper degree of condensation 

 is reached. When crystals begin to form in the 

 pan, the process goes forward rapidly, and the mass 

 is quickly cooled, and the crystallized sugar, in a 

 small amount of liquid, is let out into centrifugal 

 separators, with fine metal gauze in their linings. 

 These vessels revolve at high speed, and the 

 molasses flies out through the screens, while the 

 granulated part of the sugar remains behind. It is 

 just as we see it in the markets. If the molasses 

 is not all thrown off, we have a moist sugar, in- 

 stead of the granulated, dry kind. 



Molasses is made by heating the cane juice to a 

 temperature that converts much of the sucrose 

 into " invert sugar," a form that will not crystal- 

 lize. So sweet and rich is the syrup that it has 

 great food value, and is one of the valuable by- 

 products of sugar making, in all the old processes. 

 Only the vacuum pan prevents the formation of 

 invert sugar, and the molasses resulting from this 

 process is almost worthless* as food. The fer- 

 mentation of this low-grade molasses produces 



