EXTRACTION. Purchase.—In the beet-sugar industry, the manufacturer very seldom grows the whole of the beet that he works up, though he almost invariably raises a considerable proportion. The basis upon whioh the manufacturer purebfuses from the grower is a matter of importance to both. It is the interest of the manufacturer to base payment upon the quantity of sugar delivered in the roots. To buy and sell on the weight of roots is unfair to both, taking no account of the quality of the article, and removing all inducement to grow the most highly saccharine kinds. To make an average analysis of a crop, would be very inconvenient ; but as the juice is denser according as it is richer in sugar and poorer in other salts, it has been customary to base the value on this, taking for foundation a sp. gr. of 1.055 (7.27° B.), called 5.5 degrees, and raising the price proportionally above that figure. It has likewise been suggested that the price should be subject to a corresponding reduction for juice below 5.5, but this ia generally deemed unfair to the grower, as only arising through unpropitious seasons and other causes not within his control.
An objeotion to this scale is that the progressive value is not geometrically increased with the greater richness, whereas the yield of sugar is known to be augmented disproportionately in rich juice. Thus, to produce 100 lb. of sugar will require ; 1333 lb. of beetroot at 121 per cent.; 1593 at 11 ; 2213 at 9. In other words, while 620 lb. are needed to compensate for the diffiarence between 9 and 11, only 200 are necessary to counterbalance that between 11 and 121.
When the roots are delivered at the factory, after having been deprived of leaves, rootlets, and neoks (the portion growing above ground), they are weighed, and a " tare" is deducted for earth, badly-trimmed necks, and other useless matters. This is the point at which the manufacturers' and cultivators' interests clash; in Germany, this weight is also the basis of taxation of the industry. When the crop is paid for according to the density of the juice, a certain number of roots are selected as a sample, their pulp is rasped up, and the juice is expressed and tested by a hydrometer. Several instruments have been devised for rapidly dealing with sufficient roots for this purpose, the most important being those of Possoz, Violette, and Thomas.
Transport.—The transport of the roots from the fields to the factory may bo performed by rail, road, or river, where such facilities exist ; but the rope-tramway system presents many advantages, as it abstracts nothing from the land under cultivation, is very cheap, and can be moved about as circumstances require. The labour, cost, and difficulty of conveying enormous quantities of roots to the factory, xvhere the juice is to be utilized and the pulp returned, have drawn attention to means of transporting the juice alone, which has been independently extracted on the farm pro ducing the beet. A few years since, Linard, of Cambray, introduced a plan of sending the juice to a central factory by means of an underground system of piping, which is gaining favour in France aud Belgium. A single factory is thus enabled to work up what would otherwise have to
be distributed among several factories, effecting at the same time great economy of transport, fuel, plant, and labour. The juice, obtained by any of the methods to be described later, is received in gauge-tanks, treated with 1 per cent. of lime, and purnpcd into the cast-iron subterranean conduit, capable of withsta,nding a, pressure of 15 atmos., and of a diameter (varying with the distanoe) of 2i-5 in. The juice is received at the central factory in large store-tanks. There is no apparent effect upon the pipes after several years' constant use. The set at Cambray takes the juice produced by 10,250 acres of beet.
Cleansing the Roots.—The first step towards extracting the juice from the roots is to free the latter from foreigu matters. With this object, the roots axe oonveyed to a room capable of containiug 2-3 days' supply. The damage done to machinery by the presence of stones has led to the intro duotion of " stoning-machines." The stoner invented by Collas, of Dixmude, and made by Lecointe et Villette, is shown in Figs. 1294-5. The tank a is divided into two compartments by partitions b c, forming between them a right angle, the vertical one b constituting a strainer at its upper part, and the horizontal one occupying only about of the length of the box, fixed at a certain distance above the bottom, and having a circular central orifice. Therein is placed a horizontal screw d with 4 arms, similar to those used in navigation. A horizontal grating is provided in the compart ment m on the left, in prolongation of the horizontal partition on the right, and an inclined grating e in that (n) on the right, above the vertioal partition. The apparatus being filled with water, and the sorew set in motion by tho bevel-wheels f, a circulatory movement is communicated to the water, which rises in the compartment m, passes above the strainer, and, traversing the inclined grating e, returns to the compartment n, and again comes under the influence of the screw. If beets are thrown into this rapid current in the compartment m, the stones rest on the grating or fall to the bottom, while the roots, by virtue of their relatively small sp. gr., are taken up by the current of water on to the inclined grating e, and tossed out of the machine by a little drum g armed with sloping flanges h, and driven by cog-wheels A trap-door h allows the vessel to be emptied of dirty water, and of the mud and stones which collect on the bottom. A vertical panel 1 of sheet iron, placed above the compartment na, prevents the beets falling directly on the inclined delivery grating, and protects the driving-gear from splashings of water. The machine is already employed in several factories, beiug generally placed after the washer, and :performing a second washing, which is especially valuable when the diffusion process is adopted.