THE CONTROL OF THE FACTORY 551 



Syrup does not require any preservative provided the containers are 

 scalded each time after use. 



Bagasse may be preserved for several hours by the liberal use of formalde- 

 hyde. This material is, however, best analysed immediately after sampling. 



Control of the Milling Plant.* The control of the milling plant is concerned 

 mainly with the determination of the quantity of juice and sugar extracted 

 from the cane, and with an oversight on the efficiency of the operations made 

 in this connection. The control may be positive, i.e., with the actual de- 

 termination of the weights of cane, mixed juice, added water and bagasse; 

 or inferential when the above quantities are partly determined from the 

 results of analyses. 



Before giving the methods used it is necessary to explain at some length 

 various points connected with the constitution of the cane. 



The juice in the cane is not of uniform composition and may roughly 

 be divided into pith juice and rind juice. The pith juice is that of higher 

 density and is expressed first. Hence the average composition of all the 

 juice in the cane is lower than that first expressed. 



In addition to juice proper, there is the watery protoplasm of the living 

 cell and water of constitution loosely combined with the fibre which perhaps 

 exists in a hydrated state. This constitutional water is expelled on drying 

 at 100 C. 



The writer prefers to regard for the purpose of technical control the proto- 

 plasmic and constitutional water as juice and to define as the absolute juice 

 of the cane everything not fibre as determined directly or indirectly (by 

 difference) by drying to constant weight. 



As the result of analyses he found on an average that the relation, 

 Brix of first-expressed juice X 0-975 = Brix of absolute juice, held. This 

 figure refers to an extraction of about 60 per cent, on the weight of the cane. 



The very able chemists in Java have taken the opposite view, and 

 determine and record the constitutional water as distinct from the juice. 

 The method there employed is as follows : The last mill bagasse is pressed 

 in a hydraulic press at a pressure of about 600 Ibs. per sq. in. The expressed 

 juice is assumed to be residual juice and its percentage of sucrose is deter- 

 mined. Simultaneously the percentage of sucrose and of water in the bagasse 

 is determined by drying, and, of course, the constitutional water is here 

 included. Let the constitutional water per unit of dry fibre be w, then 

 r i m mw, where r is the residual juice and m is the fibre per unit 

 of bagasse. If the residual juice contains s sugar and the bagasse contains 

 b sugar, then b = s (i -- m -- mw). Solving this equation w is found, 

 giving the quantity of constitutional water in the bagasse. 



The methods used by the writer follow. 



In practice a number of cases may occur, such as : i. The weight of 

 mixed juice alone is known. 2. The weight of cane and mixed juice is 

 known. 3. The weight of cane, mixed juice, and added water is known. 



Case i. The complete solution of case i demands a knowledge of the 

 percentage of fibre in the cane and the application of the equation : 

 Cane + Water = Mixed Juice -j- Bagasse. Data for solution of this equation 

 can be obtained from the ordinary routine analyses and one measurement 

 as under. Let / be the fibre in cane, m be the fibre in bagasse, B c , Bj, B m 



* The first attempt to give a system of mill control is, the writer believes, to be found in Pimienta's " Manuel 

 el cultivo del cafta de azucar," Madrid, 1881. 



