SECTION XIII. Sugar. Sugar is produced, to a certain extent, by almost all vegetables, and from different parts of the plant, but chiefly the stem, root, and flower; and there are many of them in which the quantity is sufficient to enable the grower to collect, concentrate, and purify it for use. Of these the chief are the saccharum officina. rum, or sugar-cane; the acer saccharinum, or sugar-maple, and a variety of beta, denominated the red beet-root. Besides these, the inhabitants of New Spain procure sugar from the agave Americana, and others from the asclepias syriaca, and zea mays, or Indian corn. Nor are the inhabitants of high northern latitudes wholly destitute of vegetables which furnish this useful article; for at Kamschatka it is obtained from the heraleum syphondylium, and the fucus saccharinus. Sugar, when pure, is perfectly transparent; and if crystallized, colourless; but when granular, of a pure glossy white, soluble in water and alcohol, without smell, and with the taste of simple sweetness, totally void of flavour. It melts by heat into a clear, yellowish, tenacious liquid; and when kindled, burns with a strong flame, and a very pungent acid vapour. With the nitric acid it is convertible chiefly into the oxalic acid. It is a most powerful antiseptic, and is one of the most grateful and (when in mixture) one of the most nutritive of all the alimentary substances derived from the vegetable kingdom. Sugar is never found pure, and very rarely in a state pproaching to purity; for it is always intimately combined with mucilage and other vegetable principles, to which it largely imparts its peculiar taste. Cane Sugar. Saccharum officinarum.-LINN. The plant from which this useful material is commonly obtained is the saccharum officinarum of Linnæus. It is prepared from the expressed juice boiled with the addition of quick-lime, or common vegetable alkali. It may be extracted also from a number of plants, as the maple, birch, wheat corn, beet-root, skirret, parsnips, dried grapes, &c. by digesting in alcohol. The alcohol dissolves the sugar, and leaves the extractive matter untouched, which falls to the bottom. It may be taken into the stomach in very large quantities, without producing any bad consequences, although proofs are not wanting of its mischievous effects, by relaxing the stomach, and thus inducing disease. It is much used in pharmacy, as it forms the basis of syrups, lozenges, and other preparations. It is very useful as a medicine, to favour the solution or suspension of resins, oils, &c. in water, and is given as a purgative for infants. Sugar is every where the basis of that which is called sweetness. Its presence is previously necessary, in order to the taking place of vinous fermentation. Its extraction from plants which afford it in the greatest abundance, and its refinement for the common uses of life, in a pure and separate state, are among the most important of the chemical manufactures. The sugar-cane, however, yields sugar in a proportion so much larger than that in which the same matter is to be obtained from any other, that only this cane has been as yet cultivated expressly for the purpose of affording sugar to the extraction of the manufacturer. This cane has been from the most ancient times known in Asia. Of its produce, some small proportion appears to have been, during the greatness of ancient Rome, imported by circuitous channels into Europe. In the progress of the subsequent ages, the plant itself became known in Europe, and was introduced into cultivation. Before the data of the discovery of America, it was no uncommon cultivation in Spain: the Spaniards carried out plants of the sugar-cane to America; but the plant had been, even before, propagated in this hemisphere. They had not long been seated in their new colonial territories before they made sugar a principal article in their agriculture and manufacture. It has continued ever since to be the principal produce of the European colonial territories in the West India isles. It is produced also in very large quantities in the East. The AngloAmericans extract it from the maple-tree. The cane is a produce of all the South Sea isles of late discovery. The following is the mode of its manufacture in the West Indies. The plants are cultivated in rows, on fields enriched by such manures as can most easily be procured, and tilled with the plough. They are annually cut. The cuttings are carried to the mill. They are cut into short pieces, and arranged in small bundles. The mill is wrought by water, wind, or cattle. The parts which act on the canes are upright cylinders. Between these the canes are in serted, compressed, squeezed till all their juice is obtained from them, and are themselves, sometimes, even reduced to powder. One of these mills, of the best construction, bruises cane to such a quantity as to afford in one day, 10,000 gallons of juice, when wrought with only ten mules. The expressed juice is received into a leaden bed. It is thence conveyed into a vessel called the receiver. The juice is found to consist of eight parts of pure water, one part of sugar, one part of oil and gummy mucilage. From the greener parts of these canes there is apt to be at times derived an acid juice, which tends to bring the whole unseasonably into a state of acid fermentation. Fragments of the ligneous part of the cane, some portions of mud or dirt, which unavoidably remain on the canes, at the blackish substance called the crust, which coated the canes at the joints, are also apt to enter into contaminating mixture with the juice. From the receiver the juice is conducted along a wooden gutter, lined with lead, to the boiling-house. In the boiling-house it is received into copper-pans, or cauldrons, which have the name of clarifiers. Of these clarifiers the number and the capacity must be proportioned to the quantity of canes, and the extent of the sugar plantation on which the work is carried on. Each clarifier has a syphon or cock, by which the liquor is to be drawn off. Each hangs over a separate fire; and this fire must be so confined, that by the drawing of an iron slider, fitted to the chimney, the fire may at any time be put out. In the progress of the operations, the stream of juice from the receiver fills the clarifier with fresh liquor. Lime in powder is added, in order to take up the oxalic acid and the carbonaceous matters which are mingled with the juice. The lime also in the new salts, into the composition of which it now enters, adds itself to the sugar, as a part of that which is to be retained by the process. The lime is to be used in the proportion of somewhat less than a pint of this substance to every hundred gallons of liquor. When it is in too great quantities, however, it is apt to destroy a part of the pure saccharine matter. Some persons employ alkaline ashes, as preferable to lime, for the purpose of extracting the extraneous matter; but it is highly probable that lime, judiciously used, might answer better than any other substance whatsoever. The liquor is now to be heated almost to ebullition. The heat dissolves the mechanical union, and thus favours the chemical changes in its different parts. When the proper heat appears, from a rising The liquor scum on the surface of the liquor, to have been produced, the fire is then extinguished by the application of the damper. In this state of the liquor, the greater part of the impurities, being different in specific gravity from the pure saccharine solution, and being also of such a nature as to yield more readily to the chemical action of heat, are brought up to the surface in a scum. After this scum has been sufficiently formed on the cooling liquor, this liquor is carefully drawn off, either by a syphon, which raises a pure stream through the scum, or by a cock drawing the liquor at the bottom from under the scum. The scum in either case sinks down unbroken, as the liquor flows; and is now, by cooling, of such tenacity, as not to bend to any intermixture with the liquor. The liquor drawn, after this purification, from the boiler, is received into a gutter or channel, by which it is conveyed to the grand copper, or evaporating boiler. If made from good canes, and properly clarified, it will now appear almost transparent. In this copper the liquor is heated to actual ebullition. The scum raised to the surface by the boiling, is skimmed off as it rises. The ebullition is continued till there be a considerable diminution in the quantity of the liquor. now appears nearly of the colour of Madeira wine. transferred into a second and smaller copper. An addition of limewater is here made, both to dilute the thickening liquor, to detach superabundant acid, and to favour the formation of the sugar. If the liquor be now in its proper state, the scum rises in large bubbles, with very little discolouration. The skimming and the evaporation together produce a considerable diminution in the quantity of the liquor. It is then transferred into another smaller boiler. In this last boiler the evaporation is renewed, and continued till the liquor is brought to that degree of thickness at which it appears fit to be finally cooled. The cooler is a shallow wooden vessel of considerable length and wideness, commonly of such a size as to contain a hogshead of sugar; the sugar, as it cools, granulates, or runs into an imperfect crystallization, by which it is separated from the molasses, a mixed saccharine matter, too impure to be capable even of this imperfect crystallization. To determine whether the liquor be fit to be taken from the last boiler, to be finally cooled, it is necessary to take out a portion from the boiler, and try separately, whether it does not separate into granulated sugar and molasses. From the cooler the sugar is removed to the curing-house. This is a spacious airy building. It is provided with a capacious cistern for the reception of molasses, and over the cistern is erected a frame of strong joist-work, unfilled and uncovered. Empty hogsheads, open at the head, bored at the bottom with a few holes, and having a stalk of plantain leaf thrust through each of the holes, while it rises at the same time through the inside of the hogshead, are disposed upon the frames. The mass of saccharine matter from the coolers is put into these hogsheads. The molasses drip into the cistern through the spongy plantain stalks in the holes. Within the space of three weeks the molasses are sufficiently drained off, and the sugar remains dry. By this process it is at last brought into the state of what is called muscovado, or raw sugar. This is the general process in the British West Indies. In this state our West India sugar is imported into Britain. The formation of loaves of white sugar is a subsequent process. In the French West India isles it has long been customary to perform the last part of this train of processes in a manner somewhat different, and which affords the sugar in a state of greater purity. The sugar, when taken from the cooler, is here put, not into hogsheads with holes in the bottom as above, but into conical pots, each of which has at its bottom a hole half an inch in diameter, which is in the commencement of the process stopped with a plug. After remaining some time in the pot, the sugar becomes perfectly cool and fixed. It is then removed out of the hole; the pot is placed over a large jar, and the molasses are suffered to drip away from it. After as much of the molasses as will easily run off has been thus drained away, the surface of the sugar in the jar is covered with a stratum of fine clay, and water is poured upon the clay. The water oozing gently through the pores of the clay pervades the whole mass of sugar, redissolves the molasses still remaining in it, with some parts of the sugar itself, and carrying these off by the holes in the bottom of the pot, renders that which resists the solution much purer than the muscovado sugar made in the English way. The sugar prepared in this manner is called clayed sugar. It is sold for a higher price in the European markets than the muscovado sugar; but there is a loss of sugar in the process by claying, which deters the British planters from adopting this practice so generally as do the French. The raw-sugars are still contaminated and debased by a mixture of acid, carbonaceous matter, oil, and colouring resin. To free |