CLARIFICATION 61 



and it is found that if this heat be kept up, and even 

 increased, the defecation goes quicker, and with 

 the purer juic"e also goes safely. Less lime may also 

 be used, but not to the extent of making the first 

 carbonatation imperfect, which would impede the 

 filtration. 



In Java, where a large quantity of white sugar is 

 now turned out fit for direct consumption, the carbona- 

 tation process has been adopted in many factories, 

 and at one time it seemed probable that its use would 

 go on increasing. In cane juice there is a small quantity 

 of glucose. In the ordinary defecation, at a high 

 temperature, the lime attacks the glucose and forms 

 dark coloured, viscous substances which are most 

 inconvenient. But when working at the lower tem- 

 perature of the carbonatation process these lime salts 

 are partially insoluble, the rest being colourless and 

 innocuous. The juice becomes clear, light in colour, 

 and easily filtered and evaporated. Much more of the 

 gummy matters are thrown down than in the ordinary 

 defecation process. A second carbonatation is just as 

 necessary with cane as with beetroot juice, and for the 

 same reason. The first filtration must take place while 

 the juice is still alkaline, otherwise part of the pre- 

 cipitate would be redissolved, and the juice would 

 become coloured. Considerable quantities of lime are 

 necessary in order that the viscous precipitates may be 

 mingled with sufficient lime to make the filtration go 

 well. It is rather difficult to secure absolute neutrality 

 in the final juice and, therefore, a further saturation 

 with sulphurous acid is sometimes found advisable, 

 which also improves the colour of the juice. 



This carbonatation process is evidently a more 

 expensive operation than ordinary defecation, but if 

 white sugar is to be made direct from the cane juice 



