VARIOUS METHODS FOR THE EXTRACTION OF JUICE. 281 



impression widely prevailing, although not sustained by the tests of 

 repeated experiments, as its importance demands, that the juice ex- 

 pressed by heavy and slowly-revolving rolls has its increased quantity 

 fully offset by its diminished quality. 



It is urged, therefore, that, in the place of increased pressure and 

 heavier mills, the pressure should rather be diminished, but continu- 

 ally repeated ; and this view has led to the experimental adoj^tion of 

 more rolls — as four arranged in two pairs — the bagasse from the first 

 two being received and again pressed by the second pair. This is, in 

 effect, ouly a modification of the three-roll mill, so far as repeated 

 pressure is concerned ; but, by separating the two pairs of rolls, op- 

 portuuity is offered to sprinkle the bagasse, or steam it, before it passes 

 the second rolls. This is called maceration, and will be considered by 

 itself, below. Mills with five, six, and even nine rolls, have been 

 employed ; but generally the result of such experiments has been the 

 final return to the three-roll mill. 



The objections to the use of the greater number of rolls being the 

 cost of mill, the increased power required, and the grinding up of the 

 bagasse by the repeated pressure. 



^. Disintegration of the Cane. 



Several methods have been devised, depending for their efficiency 

 upon the grinding up of the cane in a pulp, and the extraction of the 

 juice by hydraulic presses. One machine, in its construction resem- 

 bling the common mill for mincing meat, consists of a series of knives 

 on a central shaft, revolving in a cylinder, upon the inner surfiace of 

 which another series of knives are arranged, which meet those upon 

 the central shaft in the manner of shear blades. By the spiral ar- 

 rangement of these sets of knives, the cane, which is fed in at one end, 

 is cut up, carried along, and discharged as pulp at the other end of 

 the machine. A machine of the above construction, at Guadeloupe, 

 having a capacity of five tons of cane per hour, gave, in five experi- 

 ments, the following per cent of juice, the pulp being subjected to 

 pressure by means of a hydraulic press: 70.0, 72.7, 75.6, 76.2, 76,8, 

 or an average of 74.26 per cent. 



Another machine consists of a series of circular saws upon a common 

 shaft, the bundles of cane being by them converted into sawdust, 

 which is subjected to pressure, as in the former case. 



3. Maceration. 

 This process, which, by one method or another, has been the subject 

 of repeated experiment, consists in moistening the bagasse as it comes 



