THE CARBONATION PROCESS. 



Chemistry of the Process. The chemistry of the process is thus 

 explained by Geerligs 1 . At temperatures near the boiling point the action of 

 lime on glucose is to form chiefly saccharic and glucinic acids : if the tem- 

 perature, however, does not rise above 60 C., saccharic and lactic acids are 

 chiefly formed, and only small quantities of glucinic acid. The glucinic acid 

 formed combines with the lime to produce an insoluble basic glucinate ; this 

 basic glucinate is insoluble in an alkaline medium at temperatures below 60 C., 

 but redissolves with rise of temperature or on neutralization of the free alkali. 

 In the single process, then, the glucinate of lime, after being insoluble, again 

 becomes soluble, and re-enters into solution ; in the double process it is 

 removed. 



In addition to the action of an excess of lime on glucose, gummy and 

 other matters are only precipitated by an excess of lime and considerably more 

 impurities are thrown down by the excess of lime than in the ordinary process ; 

 on neutralization these bodies redissolve, and the final effect is the same as if 

 lime had only been added in the usual quantities. This effect takes place in 

 the single process, and it is only by filtering the strongly alkaline solution, and 

 by removing the lime afterwards that the full benefit of the carbonation pro- 

 cess is obtained. 



Below are given details of analyses (by Geerligs) of juices treated by the 

 carbonation process ; analyses of the scums are given in the succeeding chapter. 



Sugar, Glucose, Pectine, 



Per Per Glucose Per 



Brix. cent. cent. Purity, ratio. cent. 



Mill juice 18.4 .. 15-72 .. 0'92 .. 85-6 .. 5'9 .. 0'634 



Clarified by defecation 18-6 . . 15'99 . . 0'95 . . 86-1 . . 5-9 . . 0-292 

 Clarified by carbonation 16'9 . . 14-65 . . 0-44 . . 86'7 . . 3*0 . . 0-142 



Use of Carbonation Process. The double carbonation process 

 is used in a few factories in Java, and perhaps in one or two elsewhere. By 

 its use a white sugar intended for direct consumption is obtained with less 

 trouble than can be obtained by any other process ; in this regard, however, 

 the writer would remark that the best white sugars of Mauritius made by a 

 defecation process combined with the use of sulphur and phosphoric acid are 

 equal to any that he has seen prepared by the carbonation process. 



The single carbonation process appears to be adapted to factories which 

 obtain a gummy juice, and is not adapted for making white sugars. 



Effect on Manufacture. The decomposition of the glucose by 

 lime gives rise to organic acids and hence carbonated juices contain more salts 

 than do defecated juices. In discussing this point, Geerligs 2 in 1895 seems 

 to imply that carbonation molasses contain more sucrose per unit of water 

 than do defecation molasses; this distinction he correlates with his Theory 

 of Molasses (cf. Chap. XIX.) ; ou the other hand he points out that owing to 



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