98 



The operation of boiling down lasts from 7 to 8 

 hours. When finished, air is let in to the apparatus 

 and the mass is discharged. 



7. DRYING IN THE TURBINES OR CONTRIFUGALS. 



The boiled syrup is run into reservoirs of the ca- 

 pacity of one boiling, in which it very soon becomes 

 a crystallized mass. It has now only to be drained 

 off and the sugar dried in the turbine. 



As the mass has become nearly solid and would 

 offer some obstacles to the draining, on account of 

 the large pieces of sugar, it is passed through a 

 crushing mill, where it is mixed with a small quan- 

 tity of syrup raised to 30 or 32 B. Thus reduced 

 into a sort of pulp, it is placed in the turbi^ s. The 

 charge for each turbine is 150 pounds. Th; ! machine 

 is then started. The mass sticks evenly to the cir- 

 cular walls of the drum which stops the grains of 

 sugar, but the liquid, driven by the centrifugal force, 

 traverses the solid portion, which it clarifies by 

 taking away its impurities, through the wire cloth 

 and runs out into reservoirs. The machines a re left 

 in motion for a quarter of an hour. 



The sugar has become dry. To whiten it, a 

 stream of dry steam is directed into the drum for a 

 few seconds, which completes the purifying of the 

 Crystals and renders them white. The turbine is 

 stopped, and the sugar taken out and placed in sacks 

 for transport or sent to the store. 



.operation thus gives 90 pounds of sugar, 



