A wooden trough is laid upon the beams, e e, at w, to receive the juice ex pressed from the canes by the rollers ; the holes in the bottom of this trough, through which the pivots of the rollers pass, have their orifices above the surface of the liquor in the trough, so that it can not get down to the friction rollers. A small trough leads from the trough at le, and conveys away the liquor,(going un der the mule walk,) to the boiling house.
The operation of the machine is ex ceedingly simple ; a person presents the ends of the canes to the rollers, f g ; by their motion the canes are drawn in be tween them ; another person behind bends the ends of the canes as they come through, that they may pass between the other two, sf h, and thus come out again in the front of the machine, squeezed dry from the juice they before contained. The juice which is collected is conveyed to iron boilers, where it is boiled, with the the addition of a small quantity of quick lime, and the impurities which rise to the surface are scummed off. The boiling is continued till it acquires the consistence of syrup, after which it is put into shallow vessels, where it is allowed to cool and granulate. In general, it is afterwards put into hogsheads, in which it is imported to Europe, the bottoms of which are per forated, that the molasses, with which the sugar is mixed, may be allowed to drain oft Sometimes it is put into conical earthen vessels, open at both ends, the base of which is covered with moist clay, so that the water filters through the su gar, and carries with it a greater quantity of the molasses, and other impurities. The sugar thus treated is called clayed sugar. It is not different from the for mer, but being somewhat purer. The addition of quicklime in the boiling is supposed to take up some vegetable acids which prevent the granulation of the su gar. In this state the sugar is known in commerce by the name of raw or Mus covado sugar. It is still further purified by dissolving it in water, and boiling, when the impurities, which rise to the surface, are again removed : a quantity of lime is also added, and it is clarified with blood. When boiled down to a proper consistency, it is put into unglazed earthen vessels, of a conical shape, and inverted, to allow the water from the moist clay, with which the base of the cone is covered, to pass through su gar, and carry off its impurities.
According to the number of processes to which it has been subjected, it is call ed single or double refined sugar. Sugar in this state is of a white colour : it is well known for its sweet taste ; it has lit tle or no smell. It has some degree of transparency when it is crystallized. It is considerably hard, but it is brittle, and may be easily reduced to powder. It is phosphorescent in the dark. When the solution of sugar in water is concentrat ed, it crystallizes in the form of six-aided prisms, terminated by two-sided summits. The specific gravity of sugar is 1.4. When sugar is exposed to heat, it melts, swells up, becomes of a dark brown or black colour, emits air-bubbles with a pe culiar smell, which has been called cara mel. If a red heat be applied, it sudden ly bursts into flames, with a kind of ex plosion. It is very soluble in water ; at so low a temperature as 48° water dis solves its own weight of sugar. This power increases with the temperature of the water. When water is saturated with
sugar, it is called syrup, which by concen tration and rest affords crystals. Sugar is soluble in many of the acids. It is de composed by sulphuric acid ; when heat is applied, the acid itself is decomposed, and converted into sulphurous acid ; and a at quantity of charcoal is deposited. Nitric acid acts on sugar with considera ble violence ; an effervescence is produc ed, nitrous gas is emitted, and the sugar is converted into oxalic and malic acids. Muriatic acid gas is slowly absorbed by sugar, which becomes of a brown colour, and acquires a very strong smell. Sugar is instantly dissolved, when it is thrown in the state of powder into liquid oxymuri atic acid ; it is converted into malic acid, while the oxymuriatic acid is deprived of its oxygen, and reduced to the state of muriatic acid. Alcohol readily dissolves sugar. One part of sugar is soluble in four of boiling alcohol. Sugar also com bines with the oils, and by this means they may he mixed with water. The fix ed alkalies combine with sugar, and de prive it of its sweet taste ; but by adding sulphuric acid, and precipitating the sul phate, which is formed by means of al cohol, the taste is restored. Some of the earths, as lime, combine with sugar, and form similar compounds. The sulphurets and phosphurets of the alkalies, and some -of the earths decompose sugar, and reduce it to a state somewhat similar to gum. Be distilling sugar in a retort, the first part of the product is water, nearly in a state of purity. Acetic acid with a little oil next comes over, and afterwards empyreuma tic oil. A bulky carbonaceous matter, which sometimes contains a little lime, remains behind. Mr. Cruikshank ob tained, by the distillation of 480 grains of pure sugar, by means of a red heat, Acetic acid and oil - - 270 Charcoal 120 Carbonated hydrogen and t 90 carbonic acid gases 480 Sugar, therefore, is composed of oxy gen, carbon, and hydrogen.
The proportions of its constituent parts, according to Lavosier, are the following: Oxygen 64 Carbon 28 Hydrogen 8 100 Sugar is also obtained from the juice of the maple tree in North America. See MAPLE.
It has lately been proposed to extract sugar from the root of the beet ; and the attempt has been made, even in the large way, by Achard of Berlin. The process which he followed is to boil the roots, cut them into slices, and extract the juice by pressure.
Many other plants also contain sugar, either in the roots, the sap, or the seeds. It exists in wheat, barley, beans, peas, and other leguminous seeds, especially when they are young, in considerable quantity. The uses of sugar are so &millet, that it is scarcely necessary to enumerate them. In most countries, where it can be obtain ed, it may be considered in some measure as a necessary of life. It contains a great proportion of nutritious matter ; animals, when partially supplied with it, become fat and vigorous. It is not changed by the action of the air, so that it may be preserved for any length of time. It is employed to preserve other vegetable matters from putrefaction, and sometimes it is also advantageously applied to a simi lar purpose, in the preservation of animal substances. it is used likewise in the composition of some varnishes of ink, and of some pigments, to communicate to them a degree of gloss or lustre.