CHAPTER XVIII. 



THE SEPARATION OE THE CRYSTALS. 



The finally concentrated product of the juice (massecuite) consists of a 

 magma of sugar crystals and a thick viscid solution of sugar, and of all the 

 bodies present in juices. The crystals are separated from this magma by 

 means of machines known as centrifugals or hydro-extractors. Formerly 

 and to some extent still the molasses were allowed to drain from the 

 massecuite, which was packed in hogsheads with perforated bottoms. 



Receptacles for, and Transport of, Massecuites. Tank 

 System. The first massecuites are emptied into shallow wooden or iron 

 tanks arranged on the basement; from these tanks directly, or after cooling, 

 the massecuite is dug out and carried by hand to the centrifugals ; this- 

 arrangement is now but seldom found for first sugars, but still remains very 

 common for low sugars, which may be stored for periods up to a whole year. 



Tank Tramway System. The massecuites are emptied into tanks- 

 holding up to 100 cubic feet, which run on tram lines and are hence 

 capable of being wheeled to the centrifugal battery, where their contents are 

 emptied by manual labour ; alternately these tanks may discharge into a pit r 

 whence the massecuite is elevated by a chain or magma pump ; or the tanks- 

 may be on an upper floor and may discharge their contents by gravity. 



Small Can System. The massecuite is discharged into cans holding 

 about 500 Ibs. ; these cans are transported by means of trolleys, elevated 

 by means of an hydraulic lift, turned bottom upwards and their contents- 

 discharged by compressed air, a small hole being arranged in the bottom 

 wherein is inserted the nozzle of a pipe communicating with an air compressor. 

 This system has been and is still largely used, and in many ways is very con- 

 venient ; it demands, however, extensive floor space. 



Gravity System. The pans are built on a high floor and discharge 

 into receivers, whence the massecuite flows by gravity to the pug mill of the 

 centrifugals. 



Compressed Air System. The massecuites are received in closed 

 vessels and are conveyed in pipes by compressed air to the centrifugals \. 

 this method is very clean, but demands a fluid massecuite or one thinned with 

 molasses. These two last schemes are used frequently with crystallization in 

 motion. 



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