94 



Efficiency of the mills. — In a country where cane is never weighed, 

 and where in many haciendas the empty kerosene case is still the popular 

 unit of volume, it is not surprising that very little is really known 

 about the efficiency of the mills, or the losses in grinding. Bagasse 

 changes in composition so rapidly by evaporation and fermentation 

 that it is almost impossible to transport it any distance to a central 

 laboratory and there determine by analysis its original composition 

 and sugar content. Some reliable figures, of course, can be obtained 

 by establishing a temporary laboratory directly on representative hacien- 

 das and making analyses of canes and bagasse on the spot, but even 

 in this way the amount of ground which can be covered in a season 

 is limited. The only really practicable means of determining mill losses 

 accurately and at the same time with reasonable rapidity, in the case 

 of small factories having poor transportation facilities and no chemical 

 control, was found to be the determination of the factor "mill juice 

 in bagasse per 100 fiber,'^ as originally proposed by J. Lely and quoted 

 byWatts.^i 



This factor is of great practical value in that it is independent of the water 

 content of the bagasse, which may be completely dried if necessary and transported 

 a long distance before analysis, when the original weight of mill juice contained 

 per 100 parts fiber can, of course, be calculated from the per cent of fiber and of 

 sucrose in the dried bagasse and the per cent of sucrose in a separate sample 

 of juice from the mill. Strictly speaking, this factor is, from a theoretical point 

 of view, not absolutely correct, a more rigid measure of efficiency of mill work 

 being that given by Deerr " "as volume of juice in bagasse per imit weight of 

 fiber in bagasse," or 



weight of juice in unit weight of bagasse 

 weight of the fiber in unit weighli of bagasse X density of juice 



a factor which varies only from that proposed by Lely in that it takes into 

 account the specific gravity of the juice. Recent work has proved that, in 

 addition, the efficiency of a mill is also influenced by the quality as well as the 

 quantity of fiber present in the cane, so that absolutely true comparisons between 

 mills working different varieties of cane are hardly possible. The ultimate 

 criterion would be "volume of juice in bagasse per volume of fiber in bagasse," 

 and might be expressed by some such formula as 



_ weig ht of juice in unit weight of bagasse -^ specific gravity of juice 

 weight of fiber in unit weight ol bagasse -r- specific gravity (apparent) of fiber. 



As so little is as yet known concerning the difference in physical 

 properties between different varieties of cane, the analytical determina- 

 tion of such a factor would be impracticable. That canes with a hard, 

 dense fiber do as a rule 3deld a bagasse containing a lower relative 

 percentage of juice than do those possessing a soft, spongy structure 

 is a fact frequently observed, and one capable of ready demonstration. 

 With dry crushing in mills without hydraulic pressure regulators, the 



"^West Indian Bull. (1908), 9, 85. 



"Sugar and the Sugar Cane. Manchester (1905), 107. 



