246 CHAPTER XI 



Whole bagasse. Mill I. Mill II. Mill III. Mill IV. 



Weight per 100 bagasse 100 -oo 100 -oo 100 -oo 100 -oo 



Sugar per cent. ... 10-34 7 >l6 4 * 6 3 '5 1 



Fibre percent. ... 34*32 41 -56 45 -26 46-87 



These results were obtained from material resulting from a crusher and 

 twelve-roller mill, but with more completely disintegrated material affording 

 a homogeneous mass for the mills to treat this distinction vanishes. Such 

 an effect is obtained with appliances like the Searby shredder The observed 

 fall in purity of each successive fraction of juice has been responsible for 

 much inferior work in the past, following on the idea that the material 

 thus obtained might even decrease the total output of sugar. This could 

 only happen if the later extracted juice was specifically " melassigenic," 

 and of this there is not only no evidence, but there is strong evidence to 

 the contrary in that the molasses obtained from the juices of high extraction 

 are substantially of the same purity as those obtained from less efficient 

 work. To illustrate this point, in the table below are given the average 

 results of seven factories which for three years operated at a higher, and 

 for three years at a lower extraction. The purities of the juices are 

 referred to a polarization gravity basis, those of the molasses being 

 absolute. 



Crusher Mixed Defecated Last Mill Molasses Mixed 



juice juice juice juice purity. juice Extraction 



purity. purity. purity. purity. % cane. 



Low... 89-5 87-2 88-6 77-9 43-2 101 -5 93-7 



High... 89-1 85-9 87-2 72-9 42'8 112-3. 97 - 



It will be seen that against the 3-3 units rise in extraction is to be placed 

 a loss of 0-9 unit extra fall in purity as between crusher juice and mixed 

 juice, while the rise in purity due to defecation and the purity of the waste 

 molasses is substantially unaltered. 



The factories whose results are quoted were, however, fortunate in working 

 with canes of more than average purity, and in cases of less than average 

 purity the decreased purity of the later extracted juice may become a factor 

 of greater importance. 



The actual composition of bagasse may be referred to here. Twenty-five 

 years ago material containing 50 per cent, of water was regarded as well 

 crushed. Such bagasse with the limited quantities of water then used could 

 have contained but a little over 40 per cent, of fibre. There are mills now 

 working in the Hawaiian Islands which obtain as a crop average bagasse 

 with distinctly less than 40 per cent, of water, corresponding to nearly 60 

 per cent, of fibre. Elsewhere figures as high as these are not reported, and 

 46 to 47 per cent, of water would seem to represent good practice. It is 

 not heavy pressure alone to which these results are due, efficient preparation 

 and subdivision of the cane, combined with the adoption of Messchaert 

 drainage grooves, being also contributing factors. Variety of cane also 

 seems to have an influence, and those varieties classed as hard, and which have 

 a larger proportion of rind tissue, afford a bagasse with more fibre than do the 

 softer canes. This influence is well illustrated in statistics coming from 

 the Hawaiian Islands, where the higher percentages of fibre in bagasse 

 appear at those mills working up the Yellow Caledonia cane, which contains 

 a higher percentage of rind tissue. 



