A novel arrangement of diffusion apparatus, constructed by the Prager Plaschinenbau Co., is shown in Fig. 1308. It is designed to take a maximum of 250 tons of beet per diem of 24 hours. This quantity is worked in Bohemia, where the juices are very dilute ; if, instead of having juice at 3° B., it is desired to have it at 4° 13., not more than 100 tons would be treated, at a sugar loss of 0.2 per cent. on the pulp. Four workmen suffice for the daily labour. In effect, the apparatus is rotary. The 9 diffusors a of which it is composed, having the forrn of inverted truncated cones, are borne in a circle on a wheeled table b. The motive power giving the rotation is ingeniously applied, and does not exceed 1 H,P. A complete turn is made in hour. The slicing-macbine (coupe-racines) e is placed above on a special stage, and supplies the slices to each diffusor by means of an articulated funnel, formed of movable segments, so that its mouth can follow the slow rotary movements of the diffusor which it is filling, until the quantity suffices. The axis of rotation of the apparatus is oomposed of two concentric cast-iron conduits, one conveying the water, the other the steam. Between each two diffusors, is a. vertical east-irou cylindrical juice-reheater. Each diffusor being furnished with a reheater, the temperature can be regulated at convenience, three taps sufficing for each apparatus. All these taps are placed in the centre of the system, at the height of the upper mouth of tho diffusor. A stage fixed here allows a man to stand in the midst ; another.stage is placed at the same height for the workman who opens and ' shuts the diffusors, and for the one who directs the funnel.
The diffusors are closed at top by a heavy cover, rest ing upon a circular india rubber tube, thus forming a hermetic joint, steam being adulated into the tube, so that it never flattens. The outlet of the diffusors is a lateral door o opening from above ; a trough is provided for the reception of the ex hausted slices. The juice is let out by taps d below the ground. A perforated sheet-iron plate forming a false bottom prevents the slices from mingling with the juice, when the tap is opened and the outlet-vessel is completely emptied of slices. A workmau opens tbe lower doors each time a diffusor passes before the trough for the glom. A fourtb workman is occupied at the slicing-machines. The advantages claimed for this system are as follows :—Easy charging of the diffusors, the slices passing direot from the slieing-maehines, whence arises great economy of labour ; the disehaxge of the exhausted slices takes place always at the same point; the duration of the diffusion, being regulated by the speed given to the apparatus, is always the same, and not at the discretion of the work men ; there is great saving in the construction, the pipe system being central and necessarily short.
Numerous other modifi cations are being from time to time introduced. For instance, compressed air is employed instead of water pressure for effecting the final exit of the juice, so that the first diffusor, at the moment of emptying, contains only fairly dry slices.
The exhausted slices derived from the diffusors form a valuable cattle-food. But, as generally discharged, they are too wet for immediate use, and require to be passed through a press for tho removal of the excess moisture. This is commonly performed in the Kluzemann press, shown in Fig, 1309. It is composed of a screw working in a conical space, which squeezes the pulp till it contains no more than the desirable quantity of water. The objection to this press is that it breaks up the slices. Skoda, of Pilsen, Bohemia, makes a continuous press, 'which avoids this disintegra
tion of the exhausted slices. It consists of two eccentric cylinders placed one within the other, of different diameters, moving in the same direction and at the same peripheric speed. A screw causes the wet slices to fall into the inferior of the larger cylinder, and they are carried by the general movement into the limited space between the outer surface of the small cylinder and the inner surface of the large one, and which is regulated hy a double iron ring fixed on tbe inside of the large cylinder. This machine easily presses in the 24 hours the exhausted slices from 150-175 tons of beet, reduced to 40-45 per cent. of the original weight. The motive power required is about H.P. The price of the machine is about 280/. _ _ .
Defecation by Lime aud Carbonic Acid,—This impure juice can be clarified to some extent by simple boiling, as the albuminous (nitrogonous) constituents coagulate in the same way as those of cane-juice, and form a supernatant scum ; but the coagulation is very imperfect. The addition of slaked lime greatly facilitates the aggregation of impurities, by the formation of insoluble lime compounds; but a coincident effect is the prevention of the coagulation of the albuminous matters, which remain in solution till partially destroyed by boiling in the presence of the alkali. The part played by the lime is very coniplex, and not clearly made out, but it seems to displace many of the bases in combination with sulphuric, oxalic, and other acids, forming insoluble compounds with those acids, and further destroys some of the albuminous matters, as evidenced by the disen gagement of aminonia when the temperature is raised. The convenience and cheapness of lime as a defecator are obvious. Its use underwent many modifications till 1849, when carbonic acid was proposed for neutralizing the excess of lime. In this direction, successive steps were made by Rousseau, Maumene, Perier et Possoz, Cail, Frey, and Jenileck, and the process, termed " double carbonation " (double earbonatution), has come into almost universal use, The method of cariying it into practice is as follows :—(1) Put lime into the juice as soon as possible, even into the mixture of juice and pulp, by introducing milk of Hine into the rasper, or a weak solution of sucrate of lime, which, under proper conditions, does not appreciably alter the value of the pulp as a cattle-food. (2) Let the contact of lime and juice be sufficiently long, such as when preserving juice in cisterns, in the store-tanks at the exit from the rasping, or when trans mitting it through the Linard pipe system (p. 1836); thus the free acids which would alter the sugar are saturated, and a very satisfactory cold defecation is obtained. (3) Introduce the turbid juices into the first-carbonation vessels, described further on, then adding to ago of lime in the state of milk of lime. (4) Pass carbonic acid gas in the cold up to about the middle of the carbonation; then gently admit steam to warm the juice ; the supply of carbonic acid is stopped when the juice does not contain more than of lime. (5) Turn the steam on full till the temperature reaches 90° (194° F.), to throw up the scum ; allow to rest, and decant. (6) Transfer the clear juice to the second-carbonation boilers, add to it,g„ of lime, and heat to boiling, in order to destroy the nitrogenous matters not eliminated by the first carbonation. (7) Pass carbonic acid till the lime is completely saturated. (8) Give a rapid boiling, allow to settle, and decant.