CANE SUGAR. 



which the megass travels, finally overflowing at the end next the earlier mill 

 whence it passes to the boiling house. 



Macerating baths may also be arranged between the last two mills of a 

 train, say, of three mills ; in this arrangement the expressed juice from the 

 last mill is returned to the bath in front of the last mill ; the added water 

 enters the bath immediately behind the returned juice. The flow of the juice 

 is as described above, and on leaving the bath it is pumped to the bath 

 between the first and second mills, and on overflowing from this bath passes to 

 the boiling house, together with the juices expressed from the first and second 

 mills. 



In another scheme, the juice expressed from the second mill is also 

 returned to the bath between the first and second mills along with the third 

 mill juice, and finally added water may be used in this bath as described 

 above, the juices from the second and third mills passing separately to the 

 boiling house. 



The juice in the baths is removed before the mills stop, by ceasing to 

 return the juices for about 30 minutes before closing down ; the megass, in its 

 passage through the bath, then mops up the juice present at the time that the 

 return of juices is stopped. 



Comparison of Imbibition and Maceration. In all the 



recently erected mills in the Hawaiian Islands an imbibition process is used; 

 the mills are placed close together, being driven through the train of gearing 

 shown in Fig. 112 by one engine. With this arrangement there is no 

 room for a macerating bath. The majority of plants recently erected in 

 other districts also conform to this pattern ; macerating baths are to be found 

 in Mauritius, in Fiji and in Australia, but the process is not by any means as 

 common as imbibition. The writer has always been an upholder of the 

 maceration process, and formed this opinion from the results obtained when 

 once in a position to make comparative tests. In view, however, of the balance 

 of opinion in favour of imbibition, he is unwilling to dogmatize on the subject. 



The benefit of maceration is most pronounced with the imperfectly crushed 

 megass coming from an earlier mill : generally the rupture of the cane is at this 

 stage so imperfect that the water added as imbibition is but little absorbed. 



To a certain extent the preference of engineers for a compact train of 

 gearing, and considerations of first cost, account for the more extended use of 

 imbibition ; where the mills have each their own engine, as is the case in plants 

 erected piecemeal, this objection to maceration does not hold. 



General Principles in Saturation. In conducting saturation 

 processes the following points are of importance : 



1. The water must be evenly distributed over the megass. 



2. The water must penetrate into the megass ; to this end it must be under 

 a considerable head, so as to reach the lower layers ; a pipe led under the blanket 



204 



