Page:The American Cyclopædia (1879) Volume XV.djvu/462

 446 SUGAR caseine, wax, &c. In the hot climate of the sugar plantations the juice if left to itself be- gins to ferment in the course of an hour ; it is therefore immediately treated with from -g-^ to j^j. of its weight of lime, and heated to 140 in large flat-bottomed copper pans or clarifiers holding from 300 to 400 gallons each. This coagulates the albuminous portions, which rise to the surface as scum. Some planters treat the juice with sulphurous acid, by which fermentation is delayed. The clear liquid, after cooling for an hour or two, is drawn off for concentration by boiling. The fuel used is usually the dried crushed canes, the ashes of which are returned to the soil. By the old method practised in Asia a series of 11 kettles or earthen boilers is set in a line in a rudely constructed range, at one end of which is the fire, with a large iron boiler over it, and at the other the chimney. The juice is first put into the boiler furthest from the fire, and is grad- ually transferred to the others, as the process goes on, until the final concentration is effected in the iron boiler. The product is afterward drained and the sugar is clarified by boiling again with water, an alkaline lye, arid milk. A somewhat similar arrangement of kettles, to the number of four, five, or six, has been em- ployed in this country and the West Indies, each kettle having its own fire, and the defeca- tion or partial purifying being effected during the boiling by "tempering" the liquor with slaked lime. This, when used in small quan- tity, causes the glutinous matters present to coagulate and rise upon the surface in a scum, which may be continually removed by skim- ming. It also neutralizes any acid that may have formed. In Louisiana it has been the practice to concentrate the sirup to 42 Baum6 in the last kettle, called the battery, and then transfer it to large wooden vats, called cool- ers, for granulation ; but the operations have been variously modified there, and different methods too have been pursued in the West Indies. Instead of kettles, each one requiring a separate fire, large copper caldrons are heated by steam, either by being enclosed in a steam jacket or by containing a coil of steam pipe. The clarification is effected as before by means of lime added to the sirup diffused through a portion of juice, or in the form of milk of lime of known strength and carefully graduated, so that exact quantities may be used. Just enough should be used to neutralize exactly the sirup, which may be known when litmus paper in- dicates neither an acid nor alkaline reaction. An excess of lime should be particularly guard- ed against, as it involves a loss of sugar ; and when it occurs the effect should be corrected by careful addition of alum, or better of sul- phate of alumina, which contains no potash. The heat employed in clarifying should not reach the boiling point of the sirup. At a less degree a scum gathers upon the surface, and when this breaks up into white froth, the clari- fication is completed. The heat is then stopped, and the liquor is left to repose for an hour, when it is drawn away from the scum, and is seen as it flows into the first of the evaporating pans to be of a clear bright wine-yellow color. These pans, to the number of three or more, are set in succession over a flue heated by a fire at one end. The liquor is gradually trans- ferred to the smaller pans, and as it boils away the scum that rises is taken off. It is the skimmings in these operations that furnish the best materials for distillation, and the manu- facture of rum is very generally carried on in connection with that of sugar. In the small- est and last pan, to which sometimes the term "teache" is exclusively applied, the sirup is finally collected ; and when it is judged to be sufficiently concentrated for granulating, it is transferred into the coolers, and thence into the vessels, also called coolers, in which the granulating takes place. These are of wood with thick sides, about 7 ft. in length, 5 or 6 ft. in width, and not less than a foot deep. This depth and the thick sides are re- quisite to secure slow cooling, without which the grains could not be coarse. In about 24 hours the graining takes place, the crystals forming a soft mass in the midst of the liquid portion or molasses. The separation of the two products is effected by drainage in what is called the curing house. This is a large building covering an open reservoir. Frames are provided for hogsheads so that the drip- pings from these shall flow into the reservoir. In the bottom of each hogshead several holes are bored, and into each hole is put a crushed cane or the stalk of a plantain leaf, the lower end projecting several inches below the bot- tom. The hogsheads being filled with the soft sugary mixture, the molasses gradually drains away from it, dripping from the stalks. The operation goes on for three to six weeks, till the sugar is considered sufficiently dry for shipping. It still retains considerable molas- ses, and in the moist hold of the ship the sep- aration continues, the molasses leaking away and involving a serious loss. The "Julius Robert diffusion process " for extracting sugar from cane is in use at the sugar establishment of Messrs. Koch, in Bayou Lafourche, Louisi- ana. A series of tall cylinders connected by pipes are filled with thinly sliced canes and water. The diffusion allows the hydraulic pressure to carry off the dissolved sugar. The water is heated by steam to about 190 by a boiler through which the diffusion juice passes. It is said that a much greater proportion of the sugar is extracted by this method, and that the clarifying process is much simplified and abridged. Sugar Refining. The prepara- tion of the purest varieties of sugar did not originate in the sugar-producing countries, but the art was applied first by the Venetians to the crude sugars brought from Egypt. It was practised in Antwerp in the 16th century, and was thence introduced into England. At pres- ent it is an important branch of manufacture