CANE SUGAR. 



Below are given analyses of limestones, after Gallois & Dupont 3 , classed 

 by them as bad, passable and excellent : 



Material. Bad. Passable. Excellent. 



The Effect of Lime in Clarification. The effect of lime and 

 heat on cane juice is 



1 . Some proteid and gummy matters are precipitated ; generally speaking 

 the greater the amount of gums originally present, the greater is the percentage 

 of gums precipitated. 



2. Earthy phosphates and bases of all metals except the alkalies are 

 precipitated. 



3. Mechanical impurities, as wax, fibre, &c., are entangled and caught in 

 the'proteid and gum precipitate. 



4. The juice is made capable of filtration. 



5. "With an excess of lime reducing sugars are decomposed into organic 

 acids; this action is discussed in the following chapter. 



6. The purity of the juice is elevated up to a maximum of three to four 

 units. 



The nitrogenous precipitate obtained by the action of lime consists entirely 

 of albuminoids ; xanthine bases and amides are not precipitated by lime, and 

 as amides are present chiefly in unripe cane it is in such cane that the nitro- 

 genous matter chiefly passes on to the after products of the factory. In general, 

 with lime clarification the writer's opinion is that the best results are obtained 

 with a juice very slightly alkaline, sensitive litmus paper being used as an 

 indicator, and, although considerable difference of opinion exists, he does not 

 place reliance on the value of phenolphthalein as a criterion to show at what 

 point the addition of lime should cease. It is with juices containing a high 

 proportion of reducing sugars that an excess of lime is most harmful, and its 

 evil effects are reflected through the whole course of manufacture, in low 

 masse cuites hard to purge, in viscous molasses, and in low sugars, dark 

 coloured and of low test; with juices containing little reducing sugar, an 

 excess of lime is not detrimental. 



246 



