Sugar 



95 



the acidity of the juice and so retards the inversion of the cane-sugar, and it assists in rendering 

 insoluble the albuminoids .and the various mineral substances also present. This process of 

 heating the juice to which lime has been added, is usually spoken of as " defecation," and has 

 been practised from very early times. It is often carried out in large open boiling pans, like 

 huge kitchen-coppers. The juice is run in from the mill, the proper amount of milk of lime 

 added, and the whole contents of the copper heated nearly to boiling point. The impurities 

 rise to the top as a scum, and may be removed to : a great extent by skimming. Other vessels 

 are designed so that part of the impurities settles to the bottom, and parts form a scum on the 

 top, whilst in between is a clear liquid which can be drawn off at will by a suitably placed tap. 

 Various other devices have also been designed, but the essential is the* same in each case. 



After liming and heating it remains to remove as completely as possible all the impurities 

 now reduced to an insoluble state so .that they can be got rid of by filtration. This is done 

 by passing the juice through various types of filter bags, or the more modern filter press. It 

 will be noted that the Naudet process described above allows of the heating and filtration 

 being performed practically together, and moreover uses the megass or crushed cane itself 

 as the filtering medium in place of special filter bags or presses. Defecation as described above 

 is superseded by the carbonatation process on some sugar estates. This method is described 

 under the beetroot-sugar manufacture. The juice obtained by these methods, when well 

 •carried out, is beautifully bright and clear, but dark in colour, so that it finally yields dark 

 sugars, of the type of the good and formerly more extensively used moist brown sugar, or 

 muscovado of the British West Indies, or the " basket " sugar of the East. Such sugars 



JAVA. SUGAR FACTORY WITH CENTRIFUGAL MACHINES ON THE LEFT AND VACUUM PAN IN BACKGROUND 



