CANE SUGAR. During the middle of the eight eenth century sugar-cane (q.v.) was introduced from Southern Europe into Louisiana. \limrc the successful manufacture of sugar began during the last decade of that century. Formerly the juice obtained by more o• less crude processes was evaporated in open pans (`kettles') and the molasses allowed to drain in barrels or other forms of coolers. The molasses, which was gener ally not reboiled, was superior in flavor and lighter in color than that remaining after the re moval of several crops of crystals in a modern sugar factory, because of its smaller proportion of impurities.
The modern sugar factory is equipped with every apparatus suggested by scientific research. The juice of the cane is extracted in 'mills' consisting mainly of a system of rollers, often eight, arranged in three sets, through which the cane successively passes; first, two corru gated rolls, which break and prepare the cane for the heavier pressures applied by the sue ceeding sets of three rolls each. Between the second and third set the crushed cane is sprayed with water to facilitate the removal of sugar by the last set. This process removes from 50 to 85 per cent, of the sugar. according to the effi eiency of the apparatus and the care with which it is operated. The crushed cane, called 'bagasse,' is used for fuel to furnish steam for the engines and pumpt. and for the evaporation of the juice. The diffusion process, which is used in relatively few cane-sugar factories (see Bert Sugar). se cures from 90 to 97 per cent. of the sugar, hut the bagasse is unfit for fuel.
Aside from the minor details the process of manufacture is essentially the same in each case. Fo• white sugar the juice is bleached with the fumes of burning sulphur. Lime is next added to neutralize it or to leave it faintly acid. In the subsequent heating the insoluble compounds of lime formed with the o•g_anic acids, the al buminous bodies. and other impurities rise to the surface and are removed by skimming or are precipitated. Since the quality of the sugar produced depends upon this process of clarifica tion, considerable skill and care are bestowed upon it. The skimmings and stillings. which were formerly thro\•n away, are now filtered and saved, and in many factories the clear juice is often filtered also to remove all traces of in soluble matter.
In a new and efficient process adopted by many factories during the closing decade of the last century the limed juice is pumped continuously under high pressure through pipes surrounded by steam in a chamber (`superheater') : thence it passes through a cooler in which the same pipes, extended, are surrounded by the cold juice.
which absorbs the surplus heat; and lastly it passes direct to the filter presses and settling tanks. The process is continuous, accomplishes a high degree of purification, eliminates the skimming, and is conducted in a closed apparatus.
The clarified juice containing from 10 to IS per cent. of sugar is evaporated in multiple effect vacuum evaporators, so called because the heating effect of the steam is utilized in Yaell0 as many times as there are pans in the series, steam being applied to the first pan and the vapor from the boiling juice to the second pan, and so on. From the last pan the vapor passes to a condenser, kept in constant vacuum by a continuously acting pump from which it flows away. The juice is pumped continuously through the pails, from the last of which it issues as a syrup containing about 50 per cent. of dissolved matter, including from 40 to 45 per cent. of sugar and 5 to 10 per cent. of impurities.
The 4yrup is then admitted to the 'strike' pan, a cylindrical cast-iron vessel provided with a vacuum pump, condenser, and several coils of copper tubing, to which steam may be admitted as desired. After further condensation, and when about one-fourth or one-third full of thick liquor, a fresh charge of cool syrup is admitted to cause the formation of minute sugar crystals (`grain'), the size of which can be controlled by the sugar boiler, who regulates the boiling and the admis sion of fresh syrup so as to avoid the formation of new crystals, 'false grain.' The pan is emptied when it becomes filled with a dense mass of sugar crystals and syrup. `masseenite,' which is con veyed to cylindrical metal vessels (centrifugal machines) with perforated walls and supported upon vertical shafts making from 1000 to 1500 revolutions a minute, the force throwing the syrup out through the walls. After the sugar is sprayed with water in which a little ultramarine or other harmless blue is added to correct the yellow tint, it is removed, and in the case of granulated sugar is dried in revolving drums (granulators) through which a current of warm air passes.
The molasses may be reboiled even three times for a `second.' third,' and, if exceptionally pure, even a 'fourth' sugar. In these eases the masse euites, which contain no crystals when they leave the vacuum pan, are placed in 'sugar wagons,' tanks or metal boxes on wheels, for a few hours or until crystals form. These second and third massecuites are frequently granulated in cylindrical 'crystallizers' while constantly stirred by revolving paddles, a method (`erystallization in movement') very generally adopted in modern beet-sugar factories.