540 SORGHUM. 



to neutralize the free acid found in the juice, and then to heat the 

 juice to boiling. 



The effect of the lime is not only to neutralize the free organic acids, 

 but to form with certain others of these impurities insoluble lime salts. 



The effect of the heat is to coagulate certain of the nitrogenous sub- 

 stances present in the juice. 



Upon allowing the juice which has been brought to the boiliug point 

 to stand a few moments, there will be found a heavy scum upon the 

 surface, consisting largely of the coagulated matters which have me- 

 chanically entangled and brought to the surface the fragments of cane 

 and other mechanical impurities of the juice. At the bottom of the 

 defecator will be found a sediment, more or less abundant, composed 

 largely of the lime salts formed, and which, generally being heavier 

 than the juice, will soon settle to the bottom. 



If, however, the juice is very deD.se,it will occasionally happen that 

 this sediment will remain suspended in the juice, neither rising to the 

 surface nor settling to the bottom. In such event, it will be found 

 necessary to draw the juice, after skimming, into a cooling tank, or 

 allow it to remain in the defecator until these impurities shall settle ; 

 or it may be hastened by adding to the juice, after skimming, enough 

 cold water to dilute the juice, and diminish its density, so that the 

 lime salts present may settle. By reference to the result of our experi- 

 ments already given, it will be seen that this method may be 2Hirsued 

 without loss of sugar. 



After the subsidence of these impurities, the juice may be drawn 

 from this sediment, and it will be, if the operation has been properly 

 conducted, quite clear and almost colorless. It is then to be evapo- 

 rated to a syrup as sj^eedily as possible, and such additional impurities 

 as rise to the surface, especially during the earlier stage in the evapora- 

 tion, are removed by skimming. 



The importance of removing all those impurities rendered insoluble 

 by the action of the lime and heat combined, is manifest. If allowed 

 to remain, it will be .found that they are but imperfectly removed 

 during evaporation, and remain to a great extent in the syrup, causing 

 it to be muddy in appearance, impure in its composition, and disagree- 

 able in quality. 



