CHAPTER XI 



THE EXTRACTION OF THE JUICE BY MILLS 



THE process which has finally been adopted as the standard method for 

 the extraction of the juice is one of repeated pressures exerted on the cane 

 in its passage between horizontal rollers, which revolve about their longi- 

 tudinal axes. The design of these apparatus has become standardized to 

 an extent comparable with what has been arrived at in the case of, say, 

 reciprocating engines ; the differences to be found in various plants are 

 chiefly in the number of units employed, in arrangement of details as in the 

 methods of applying " maceration water," and in various accessories, 

 several of which are of importance. In this chapter an attempt is made 

 to give a connected account of the principles involved, of the chief types of 

 mills, their combinations and accessories. 



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FIG. 77 



The Raw Material. In Chapter I is given a brief account of the botanical 

 structure of the cane ; from the point of view of the mill engineer, the cane 

 may be regarded as a hollow cylinder, the walls of which are formed by the 

 rind, the interior being filled with a soft cellular structure, the pith ; the 

 cylinder is subdivided into a number of smaller cylinders by transverse 

 partitions, the nodes, which may also be considered as formed of rind tissue. 



The material of which the rind and nodes is constructed is of a hard, 

 woody nature and contains an im purer juice, which may conveniently be 

 referred to as rind juice ; the pith is of a softer nature, and contains a purer 

 juice referred to as pith juice. Broadly then the cane may be divided into- 

 juice and fibre, including in the latter term everything which is not water 

 or is insoluble in water ; the fibre and juice may again be subdivided into 

 rind tissue and pith tissue and into rind juice and pith juice ; from another 

 point of view the cane may be divided into nodeand internode or into pith, 

 rind and node. The writer found the distribution of these divisions of the 

 raw material to be as follows 1 : 



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