The Mississippi lands on which the cane grows is almost inexhaustible, re quiring no manure for the present but only to be ploughed deeper. It is foand, however, advantageous to plough in the tops and other refuse matter of the cane. On this point, Mr. Benjamin, writing in De Bow's Review, says: " When the cane is cut in the fall, a large portion of the produce of the soil remains on the field, as is well known, in the tops and leaves of the cane, the ripe portion alone of the stalk being con veyed to the mill. This is called the trash, and is placed on the stubble to as sist in protecting from the frost that part of the cane which remains under ground, and from which the rattoons shoot up the ensuing season. As soon in the spring as danger of frost is no longer ap prehended, the trash is raked off the rows of stubble to allow access to the sun and air ; and on nearly all planta tions this trash, which is a useful and fertilizing manure, is burnt up, instead of being returned to the earth. One cause of the difficulty of making use of this trash as manure, was the narrow ness of the space between the rows under the old system of planting., which left so little room as to make the operation of ploughing in the trash difficult and la borious; but where the rows are eight feet apart, the task is easy. Independ ently of the considerations to which I snail presently advert, and which derive their force from the chemical constitu tion of the cane, it is difficult for a person who has not witnessed the results to form an adequate idea of the improve ment to a soil that is naturally at all stiff or clayey, from the mere mechanical sub division of its particles attendant on the decay of the large quantity of this trash left annually in the fields. This system was first put into operatioh last year on the plantation of which I am part owner." When the canes are ripe, they are cut and sent to the crushing-mill to separate the juice.
The mills used for grinding the cane are generally placed 10 to 12 feet from the ground, in order to give sufficient fall for the juice to flow into the juice boxes, and from them into the kettles.
The mills consist mostly of three iron rollers, from 25 to 28 inches in diameter, and from 4 to 51 feet long.
The following cut is an illustration of a horizontal sugar-mill.
The thickness of the shell of the rollers, in those mills constructed by Leeds e.r, Co., New Orleans, varies from 2+ inches to 8 inches, according to size; the depth of the eye of the roller is 12 inches in all these mills. The shafts are of wrought iron. The journals vary in size from 7+ to 8+ inches in diameter. The boxes in which the journals revolve are of brass, lined with " Babbitt's anti-attrition me tal." The return plats, about which there is a great difference of opinion re specting their proper position, are placed from 1 to 2 inches below the top roller. The cane carrier is from 50 to 90 feet in length, according to the height at which the mill is placed.
Planters who pay attention to the set ting of the rollers and the feeding of the cane carrier, obtain 66 per cent. of juice ; yet the usual amount obtained, probably, does not exceed 52 per cent. Wray re commends "the first under roller to be adjusted exactly five-sixteenths of an inch from the main or upper roller, and the second under roller just one-tenth of an inch from the upper roller." The juice so obtained, is carefully eva porated till it has acquired the proper consistency for crystallizing ; lime water is added during this operation, to neu tralize any free acid, and to facilitate the separation of certain vegetable matters, which, in consequence of the action of the lime, rise more readily to the sur face, and admit of being skimmed off. When duly concentrated, the syrup is run off into shallow wooden coolers, where it concretes ; it is then put into barrels with holes in the bottom, through which a quantity of treacle or molasses gradually drips, and the remaining sugar acquires the granular crystalline state ; it is packed into hogsheads, and comes to us under the name of raw or muscovado sugar.
The following is a sketch of the pro cess by which raw sugar is purified.
Raw sugar is chosen by the refiner by the sharpness and brightness of its grain; it is put into a copper pan or boiler, pre viously charged with a certain quantity of lime-water, with which a portion of bullock's blood has been well mixed by agitation, and is suffered to stand a night to dissolve. Early in the morning fires are lighted under the pans, and when the liquid boils, the coagulated albumen of the blood rises to the surface and car ries the impurities of the sugar with it. The liquid is kept gently simmering, and continually skimmed, till a small quan tity, taken out in a metal spoon, ap pears perfectly transparent: this general ly takes from four to five hours. The clear syrup is then run off into a cistern ; the pans are reduced to half their former size, by taking off a movable front, and a smaller portion of the purified syrup re turned into each ; the fires are now in creased, and the sugar made to boil as rapidly as possible, till a small quantity taken on the thumb is capable of being drawn into threads by the forefinger'; the fire is then damped, and the boiling syrup carried off in basins to the coolers; a fresh quantity is then pumped into the pans and evaporated as before. In the coolers the sugar is violently agitated with wooden oars till it appears granu lated. It is upon this agitation that the whiteness and fineness of grain in the refined sugar principally depend ; the crystals are thus broken down while forming, and the whole converted into a granular mass, which permits the color ed liquid saccharine matter to run off, and which would be combined with the solid if it were suffered to form into larger crystals. This granular texture likewise facilitates the percolation of wa ter through the loaves in the after pro cess, which washes the minutely divided crystals from all remaining tinge of mo lasses. That this is the real theory of the whitening of sugar by the process of refining, appears from a comparison with the process for making sugar candy. In this the raw material is cleared and boil ed as above ; but instead of being put into coolers and agitated, it is poured into pans, across which threads are strung, to which the crystals attach themselves ; these are set in a stove, and great care is taken not to disturb the liquid, as upon this depends the largeness and beauty of the candy. In this state it is left for five or six days exposed to a heat of about 95° ; when it is taken out and Washed with lime-water. This takes off the mo lasses from the outside ; but a great quan tity is combined in the crystal, and the consequence is, that candy is never whiter than the sugar it is made from. When the sugar has attained the granular state in the coolers, as above described, it is poured into conical earthen moulds, which have been previously soaked a night in water; in these it is again stirred, for the purpose of extricating the air-bub bles, which would otherwise adhere to the surface and render it rough ; when sufficiently cold, the loaves are carried to some of the upper floors of the manufac tory, and the paper covers being removed from their points, they are set with their broad ends upward upon earthen pots. The first portions of the liquid molasses soon run down, and leave the sugar much whitened by the separation ; afterwards, pipe-clay mixed with water to the con sistency of cream is put upon the base of the loaves to the thickness of about an inch ; the water from this clay filters through the loaf, and carrying with it all remaining tinge of molasses, runs into the pot, the clay being of no other use than to retain the water and prevent its too rapid percolation, by which too much of the solid sugar would be dissolved. This process, called clewing, is repeated four or five times, according to the na ture of the sugar and the degree to which it has been boiled. When the loaves are thus cleansed from all relics of color they are suffered to remain some time for the water to drain off; when this is com pleted, they are set with their points up wards, when all remains of it are equal ly diffused throughout ; they are then stove-dried at a temperature between 95 and 100.