82 MANUAL FOR SUGAR GROWERS. 



*' Sugar-cane," " The Louisiana Planter," " Sugar," 

 etc. 



It lias already been shown that by means of the 

 process known as osmose (see page 9) certain sub- 

 stances — namely, those capable of existing in a crys- 

 talline form — can pass through vegetable membranes 

 when those membranes are in contact with water on 

 both sides. 



Now, if thin slices of sugar-cane are placed in 

 water, we have the vegetable membrane of the cell- 

 wall separating water from the solution of sugar and 

 other matters in each cell ; consequently the sugar 

 of the cell, being cry stallis able, finds its way through 

 the cell-walls into the water, and the greater part of 

 the im^^urities, being non-crystalline, is left behind. 

 By repeated treatment of the chips with fresh water, 

 the whole of the sugar is removed. 



In practice this is carried out by slicing the canes 

 by means of revohdng knives, and j^lacing the result- 

 ing chips into large vessels into which hot water can 

 be forced ; the vessels vary in number from six to 

 twenty, and are arranged either in a circle or in 

 parallel rows. When the water has been in contact 

 with the chips for a given time, it is drawn off. In 

 order to effect complete extraction of the sugar, 

 the water — or, as it may now be termed, diffusion- 

 juice — is drawn down upon a fresh lot of chips, 

 and another charge of water or weak diffusion -juice 

 is run upon the partially exhausted chips. The 

 juice in this Avay passes through all the diffusion- 

 vessels in turn, water entering at one end of the 

 series, and strong diffusion-juice being drawn off 



