Sparla. Trowel. Chisel. Hammer. Loosening Stove. Crowbar Hammer. Scoop for filling Moulds.
Cane juice, as expressed by the mill, is an opaque, slightly viscid fluid, of a dull grey, olive, or olive green colour, and of a sweet balmy taste. The juice is so exceedingly fermentable that, in the climate of the West Indies, it would often run into the acetous fermentation in twenty minutes after leaving the mill, if the process of clarifying were not immediately commenced.
The processes followed in the West Indies for separating the sugar from the juice are as follows: The juice is conducted by channels from the mill to large flat-bottomed clarifiers, which contain from three hundred to a thousand gallons each. When the clarifier is filled with juice, a little slaked lime is added to it; and when the liquor in the clarifier becomes hot by a fire underneath, the solid portions of the cane juice coagulate, and are thrown up in the form of scum. The clarified juice, which is bright, clear, and of a yellow wine colour, is transferred to the largest of a series of evaporating coppers or pans, three or more in number, in which it is reduced in bulk by boiling; it is transferred from one pan to another, and heated until the sugar is brought to the state of a soft mass of crystals imbedded in molasses—a thick, viscid, and uncrystallizable fluid. The soft concrete sugar is removed from the coolers into a range of casks, in which the molasses gradually drains from the crystalline portion, percolating through spongy plantain stalks placed in a hole at the bottom of each cask, which act as so many drains to convey the liquid to a large cistern beneath. With sugar of average quality, three or four weeks is sufficient for this purpose. The liquid portion constitutes molasses, which is employed to make rum. The crystallized portion is packed in hogsheads for shipment as raw, brown, or muscovado sugar; and in this state it is commonly exported from our West Indian colonies.
Besom. Lump Mould. Loaf Mould.
The refining of sugar is mainly a bleaching process, conducted on a large scale in England. There are two varieties produced by this bleaching, viz. clayed and loaf sugar. For clayed sugar, the sugar is removed from the coolers into conical earthen moulds called formes, each of which has a small hole at the apex. These holes being stopped up, the forms are placed apex downwards in other earthen vessels. The syrup, after being stirred round, is left for from fifteen to twenty hours to crystallize. The plugs are then withdrawn, to let out the uncrystallized syrup; and the base of the crystallized loaf being removed, the forme is filled up with pulverized white sugar.
This is well pressed down, and then a quantity of clay mixed with water is placed upon the sugar, the formes being put into fresh empty pots.
The moisture from the clay, filtering through the sugar, carries with it a portion of the colouring matter, which is more soluble than the crystals themselves. By a repetition of this process, the sugar attains nearly a white colour, and is then dried and crushed for sale.
But loaf sugar is the kind most usually produced by the refining processes. The brown sugar is dissolved with hot water, and then filtered through canvas bags, from which it exudes as a clear, transparent, though reddish syrup. The removal of this red tinge is effected by filtering the syrup through a mass of powdered charcoal, and we have then a perfectly transparent colourless liquid.
In the evaporation or concentration of the clarified syrup, which forms the next part of the refining process, the boiling is effected (under the admirable system introduced by Mr. Howard) in a vacuum, at a temperature of about 140° Fahrenheit. The sugar pan is a large copper vessel, with arrangements for extracting the air, admitting the syrup, admitting steam pipes, and draining off the sugar when concentrated. In using the pan a quantity of syrup is admitted, and an air pump is set to work to extract all the air from the pan, in order that the contents may boil at a low temperature. The evaporation proceeds, and when completed the evaporated syrup flows out of the pan through a pipe into an open vessel beneath, called the granulating vessel, around which steam circulates, and within which the syrup is brought to a partially crystallized state. From the granulators the syrup or sugar is transferred into moulds of a conical form, which were formerly made of coarse pottery, but are now usually of iron. In these moulds the sugar whitens and crystallizes, the remaining uncrystallized syrup flowing out at an opening at the bottom of the moulds. This syrup is reboiled with raw sugar, so as to yield an inferior quality of sugar; and, when all the crystallizable matter has been extracted from it, the remainder is sold as treacle. The loaves of sugar, after a few finishing processes, are ready for sale.