THE CONTROL OF THE FACTORY 553 



of cane equal to unity, the weight of the added water is found from the 

 equation : 



z -]- w = 0-9115 + 0-2443, whence w = 0-1558, or the added water is 

 15-58 per cent, on cane. 



By this method, if any one of the weights of cane, mixed juice, added 

 water or bagasse be known, the others can be obtained. 



The calculation of the extraction, etc., once the actual quantities have 

 been determined, is made as shown below under Case 2. 



Case 2. — This is the case which usually occurs in modern factories, 

 namely the weight of cane and of mixed juice is knowm. The fibre in the 

 cane is not determined, but is obtained by calculation from the observed 

 fibre in bagasse. 



The method of calculation is best shown by a completely worked-out 

 example : — 



Weight of cane - - 1115-3 tons. 



Weight of mixed juice - 1016-6 tons or 91-15 per cent, on cane. 



Absolute juice - - 20-9 Brix. 



Mixed juice - - - 19-0 Brix, 16-23 per cent, sugar. 



Last mill 3 uice* - - 7-0 Brix, 5 • 74 per cent . sugar, 82-0 purity . 



Bagasse - - - - 46-8 per cent, water, 3-69 per cent, sugar. 



Then : — Soluble solids in bagasse - — ^ =4.50 per cent. Fibre 



per cent, in bagasse = 100 — 46-8 — 4-50 =48-7 per cent. 



Put the weight of cane equal to unity, and, since the soluble solids in the 

 cane are equal to those in mixed juice and bagasse, it follows that 



(I -/) X 0-209 = 0-9115 X 0-190 + ^f-^ X 0-045, 



where J is the fibre per unit of cane. 



Solving, /is found to be 0-119 or 11 -9 per cent, on cane. 



The weight of bagasse is ^ = 0-2443 or 24-43 per cent, on cane.f 



0-407 



From the relation, 



Canes -f- water = mixed juice + bagasse 

 X ^ 10 = 0-9115 + 0-2443 



w = 0-1558 or 15-58 per cent, on cane. 

 The actual quantities of material are then : — 



Cane .. .. .. .. ,. ., 1115-3 tons. 



Mixed juice 



Bagasse 1115-3 X 0*2443 



Added water 1 1 15 -3 x 0-1558 



Sugar in mixed juice, 1016-6 X 0-1623 



Sugars in bagasse, 272-5 X 0-0369 



Sugar in cane 



Sugar per cent, cane 



1016-6 tons. 

 272-5 tons. 

 173-8 tons. 

 165-0 tons. 



10 - 1 tons. 

 175 -I tons. 



15-70 



_ _ • In this example the last mill juice and residual juice in bagasse are taken as equal. Spencer uses back roll 

 juice, and in Java juice is expressed from the bagasse in a hydraulic press. Alternatively, the solids in the bagasse 

 extract obtained in the sugar determination may be found, using the pycnometer because of the extreme dilution, 

 t This computation assumes that all the fibre finds its way to the bagasse and neglects the small amount 

 which passes through the strainers into the juice. 



