The elution process is now largely used, and furnishes, in the form of suerate, about 80 per cent. of the sugar contained iu the molasses. This suerate may most advantageously replace milk of lime in the defecation of beet-juiee (see pp. 1846-7). Opinions differ as to the relative value of osmosis and elution, the question often depending upon local conditions. The balance would scent, however, to be in favour of the latter. It nee,essitates expensive plant ; but presents the advantages that, when the spirit is evaporated from the leys, the potash salts and nitrogenous matters are recoverable in a sufficiently concentrated form to be immediately available for agricultural purposes.
Manoury's Process.—Manoury has introduced another method for extracting the sugar from the sucrate of lime formed, and has worked it at the Capelle Factory, near Dunkerque, with complete success. The principle is the same as in the German elution process, but the application differs. Into a special mixer, is introduced the molasses with 3 per cent. of lime in the state of milk of lime of 20 per cent. The combination there takes place, and the sucrate of lime leaves it in a granular condition, not larger than a pea, and mixed with excess of pulverulent lime. A bolter separates the powder, while the grains fall into washers with alcohol at 40 per cent. There the sucrate is purified from soluble matters (salts and organic substances), and, from a deep brown, comes out greyish. It contains about 20 per cent. of lime, and, when dissolved in water, forms a syrup of 26° B., containing an average of 15 per cent. of sugar for 1.30 per cent. of ash. About 100 lb. of molasses give 250 lb. of sucrate. The washers being closed, the loss of alcohol, including revivification, reaches only 2 per cent. of alcohol at 40 per cent. The cost of making the sucrate is placed at 7d, per cwt. of molasses. The sucrate is used instead of lime for car bonating raw juice. The apparatus is inexpensive, the manipulation is simple, and the alcoholic putification of the granular sucrate is very perfect.
Cane-sugar (FR., Sucre de la Canne ; GER. Rohrzucker).—CULT1VATION OF THE PLANT. The Plant.—The sugar-cane is a kind of gigantic grass, belonging to the genus Saccharum. Most botanists ascribe all the sorts of sugar-cane to a single species, Saccharum officinarum [Arundo sacchariferal supposing all the forms now met with to be varieties induced by cultivation. The best authorities are not absolutely agreed upon this subject, however; and it is probably impossible to arrive at a reliable decision, while the original home of the sugar-cane remains unknown.
Varieties.—Practical ends are served by a knowledge of the characteristics developed by education in the different varieties. Many of these have been raised to the level of distinct species ; but it will suffice here to give the names by which they are generally known to planters.
1. The Bourbon cane, introduced into the W. Indies from Bourbon, came originally from the coast of Malabar, there growing as a small-sized, but soft and juicy cane ; affected by the change of climate and soil, and cultivation, it so increased in size and richness that it at length entirely superseded the old species.
2. The Otaheite canes are two ; the yellow or straw-coloured, and the purple-striped or ribbon. The former and the Bourbon are ranch alike, if they are not the same variety. With a good soil and favourable season, 1st year's plants are often 12-14 ft. high, 6 in. in circumference, and with joints 8-9 in. apart. Such yield (in Jamaica, Bengal, and the Straits) 2i-3 tons of sugar per acre. They attain maturity in 10-12 months, and require a generous soil, and attentive management. The purple-striped Otaheite cane is often called the Otaheite ribbon cane, in contradistinction to the ribbon cane of Batavia. It is hardy and esteemed, of large size, soft, juicy, and sweet.
.3. Batavian canes are four, viz., the yellow-violet, purple-violet or Java, " transparent " or ribbon, and Batavian proper. The " yellow-violet " differs from the Bourbon in being smaller, less juicy, considerably harder, of slower growth, and more erect. When ripe, its rind is thick and pith hard; but its juice is rich and abundant. It grows in inferior soil ; its sugar is of fine quality, but less in quantity than from the Bourbon. The " purple-violet," or large black cane of Java, is as thick as the Otaheite, with joints 3-7 in. apart, and is 8-10 ft. high. It yields a very sweet rich juice, but being very hard, it is difficult to crush, and affords a comparatively small quantity of juice. It is very hardy, thriving well in poor dry soils : in Jamaica, it is often planted in the outer rows, to stand the brunt of trespassing cattle. The " transparent," or ribbon cane, is much smaller than the Otaheite ribbon cane. It grows 6-10 ft. high, with joints 4-8 in. apart, and 4 in. in circumference. It is generally planted in light sandy soils, where no other cane will thrive. Though its rind is thick, and its general texture hard, yet it yields a good quantity of juice of excellent quality. The Batavian cane is common in the Straits of Malacca, where it is cultivated by the Malays. The joints are seldom more than 3-6 in. apart. In height, size, and foliage, it closely resembles the yellow-violet ; it differs in being softer, more juioy, and less hardy. In a rich soil, it is prolific, and ratoons well; but, on the whole, it is inferior to the Otaheite, while requiring an equally rich soil.