52 TROPICAL AGRICULTURE 



time to assist the process of clarification. Sulphur, phosphoric 

 acid, and other chemicals have also been used for the same 

 purpose. The purpose of adding lime is to precipitate vari- 

 ous impurities out of the juice. After this process of clarifi- 

 cation the juice is at once filtered in large filter presses for 

 the purpose of removing the mud and the precipitated im- 

 purities. The juice is then boiled in a multiple series evaporat- 

 ing apparatus to the consistency of sirup. It contains in that 

 stage about 55 per cent, solids in solution. The sirup is then 

 boiled in vacuum pans until it is condensed to the point where 

 it separates into crystalline sugar and uncrystallizable mo- 

 lasses. The whole mass at this stage is called massecuite. The 

 crystallized sugar is then separated from the molasses by cen- 

 trifugals, the sugar crystals being caught on a fine wire gauze 

 strainer with 400 to 500 meshes to the inch, while the mo- 

 lasses is thrown out by centrifugal force. The crystallized 

 sugar is removed from the centrifugal and at once packed for 

 export as raw sugar. 



The machinery concerned in the manufacture of sugar has 

 reached a stage of great elaboration and of striking perfec- 

 tion. The whole process is a continuous one from the time the 

 cane arrives at the mill until the sugar is sewed up in the bags. 



Molasses resulting from the manufacture of cane sugar 

 varies greatly in composition but contains on an average about 

 25 per cent, water; 50 per cent, sugars (40 per cent, sucrose 

 and 10 per cent, glucose and reducing sugars), 15 per cent, 

 organic material (nonsugar), and 10 per cent. ash. The low- 

 est percentage of reducing sugar occurs in Hawaii and the 

 highest in Demerara and Louisiana. The chief constituent of 

 the ash of molasses is potash in the form of a sulphate. In 

 fact, sulphate of potash constitutes about 4 per cent, of the 

 molasses. The amount of molasses obtained in the manufac- 

 ture of sugar is about 20 per cent, that of the sugar in Hawaii 

 and 40 per cent, that of the sugar in Demerara. Waste mo- 

 lasses is used in making denatured alcohol and rum, as a fuel 



