Manufacture of Sugar from Beet-Root. 153 



which this machine is driven, the finer and more pulplike will be 

 the particles removed, consequently the cells will be ruptured to 

 a gi'eater degree, and a higher per centage of their saccharine 

 contents rendered obtainable. From 800 to 1000 revolutions in 

 the minute is the speed at which they are driven in most of the 

 large establishments. It is found that sometimes the teeth of the 

 rasp will become blocked up by small particles of the root, and 

 then, owing to the rapidity of rotation, will pass over fresh sur- 

 faces without biting them : to obviate this a small jet of water is 

 allowed to trickle over the cylinder, which keeps it clear of such 

 impediments, and mixing with the pulp, falls down into a vessel 

 placed beneath to receive them. The water, in this instance, 

 performs a double service, as it not only keeps the rasping sur- 

 face true, but by a peculiar physical action, termed " endosmose^^ 

 it extracts a fresh portion of sugar from the pulpy mass, and 

 thus renders the expressed juice of greater value. 



Having now reduced the mass into a condition suitable for the 

 next operation, that of separating by pressure the liquid from 

 the solid parts, some points of importance present themselves. 

 The usual mode of effecting this separation is by enclosing the 

 pulp in stout woollen or flax bags, and submitting it to hydraulic 

 pressure. Practically, it is found that a circular shape is the 

 best for these bags, as the pressure is more equally dispersed, 

 all the particles being driven from a common centre, and there 

 are no corners. It is found also that the bag^s should be at first 

 submitted to a very slight pressure only, so that the juice, which is 

 very abundant, may have time to drain off. In this way several bags 

 are piled on each other, a perforated or channelled metallic plate 

 being placed between each ; then a force, small or great, as may be 

 desired, is applied to the top, and transmitted through the entire 

 column. When the drainage is completed, they may be sub- 

 mitted to a higher pressure, which should be gradually applied 

 at first, and increased more rapidly towards the end of the opera- 

 tion. After remaining in the press, say 10 to 20 minutes, the 

 pressure should be removed, and the bags reversed so that their 

 points of contact be changed ; the machine should then be again 

 put in action, and its highest power applied. By the first, from 

 30 to 40 per cent, of the juice is obtained, and by the two last 

 pressings from 40 to 45 per cent, more ; about 80 to 85 per 

 cent, in all. As the pulp in this state contains all the elements 

 and conditions necessary for fermentation, which would mate- 

 rially affect the yield of crystallizable sugar, it is considered 

 advisable to dip the bags, between each part of the operation, in 

 a weak solution of tannic acid (2 to 3 parts in 1000), which 

 combines with the azotized principles of the external surface in 

 contact with the air, and prevents their change. In the case of 



