i88 



CHAPTER XI 



material, the weight and composition of which was known. For each pressure 

 observations of the volume occupied by the material, or, in certain experi- 

 ments, of the volume of juice expressed, were made. Certain of the results 

 are given below, the connection between quantity of material used and the 

 quantity of cane milled in a given time being found as follows : — A 78-in. 

 mill worked at a peripheral speed of 25 ft. per minute describes 23,400 sq. in. 

 in one minute. If in one hour 100,000 lbs. of cane with 12 per cent, fibre 

 are milled, 200 lbs. of fibre correspond to 23,400 sq. ins. of roller surface. 

 In certain of the experiments the area of the material exposed to pressure 

 was 8-43 sq. ins., so that the quantity to correspond with the milling of 



100,000 lbs. of cane with 12 per cent, of fibre per hour would be ' 



^ ^ 23400 



- 0-072 lb. fibre. The results obtained showed : — 



1. The quantity of juice expressed increased with the degree of fineness 

 to which the material was divided. 



2. Material which had been once pressed up to a certain pressure was 

 allowed to expand and then repressed to the same pressure ; four pressings 

 were required before all the juice capable of extraction at the selected 

 pressure was obtained. 



The experimental data connecting the above two observations are given 

 below. The material used was chopped cane, varying in fineness from o • 25 

 inch cube to a fine meal. The tables are arranged with the coarsest material 

 at the left. All pressures at 4,740 lbs. per sq. in. ; o-882-lb. cane is used, cor- 

 responding to 147,000 lbs. per hour, in 78-in. mill at 25 ft. per min. These 

 results may be interpreted as indicating that fineness of division and re- 

 peated pressings are of more importance than a smaller number of pressings 

 at largely increased pressures. 



3. The quantity of juice expressed increased as the quantity of material 

 used decreased, as indicated in the data given below. 



All Pressures 4,740 lbs. per Sq. Inch. 



