The New England Grocer says that the manufacture of molasses is really the manufacture of sugar up to a certain stage, for molasses is the uncrystallized sirup produced in the making of sugar. The methods of manufacture in the West Indies vary very considerably. In the interior and on the smaller plantations it is made by a very primitive process, while on the larger plantations all the appliances of modern science and ingenuity are brought to bear. Each planter makes his own sugar. It is then carried to the sea coast and sold to the exporters, by whom it is shipped to this country. The quality and grade of the molasses varies with each plantation. Two plantations side by side may produce entirely different grades. This is owing to the soil, which in Porto Rico and other localities in the West Indies seems to change with almost every acre. The cane from which the sugar and molasses is made is planted by laying several pieces of it in holes or trenches. The pieces are then covered with earth to the depth of two or three inches. In about two weeks sprouts appear above the surface. Then more earth is put in, and as the sprouts grow, earth is added until in three or four months the holes are filled up.
The planting is done from August to November, and the cutting progresses throughout the greater part of the year. The cane grows to a height of seven or eight feet, in joints each about a foot long.
When the cane is in proper condition for cutting, as shown by its appearance, an army of workmen take possession of the field. Each is armed with a long, broad knife, like a butcher's cleaver. They move down the lines of cane like an army, and while the cutting is going on the fields present an interesting sight, the sword-like knives flashing in the sun, the 300 or 400 laborers, the carpet of cut cane, the long line of moving carts, and the sea of standing cane, sometimes extending for miles and miles, stirred by the breeze into waves of undulating green. The laborers employed on these plantations are largely negroes and Chinese coolies. When the cane is ripe, they proceed to the field, each armed with a matchet. Spreading over the plantation, they commence the cutting of the cane, first by one cut at the top, which takes off the long leaves and that part which is worthless, except as fodder for the cattle. A second cut is then given as near the root as possible, as the nearer the ground the richer the cane is in juice. The cut cane is allowed to fall carelessly to the ground.
Other workmen come with carts, pick it up, tie it in bundles and carry it to the mill. The cutting of the cane is so adjusted as to keep pace with the action of the mill, so that both are always at work. Two gangs of men are frequently employed, and work goes on far into the night during the season, which lasts the greater part of the year.
As before stated, some of the methods of manufacture are very simple. In the simplest form, the sugar cane is crushed in a mortar. The juice thus extracted is boiled in common open pans. After boiling a certain length of time, it becomes a dark colored, soft, viscid mass. The uncrystallized sirup is expressed by putting the whole into cloth bags and subjecting them to pressure. This is molasses in a crude state. It is further purified by reboiling it with an addition of an alkaline solution and a quantity of milk. When this has continued until scum no longer arises, it is evaporated and then transferred to earthen jars. After it has been left for a few days to granulate, holes in the bottom of the jars are unstopped, and the molasses drains off into vessels placed to receive it. Another process of extracting molasses is as follows: By various processes of boiling and straining, the juice is brought to a state where it is a soft mass of crystals, embedded in a thick, but uncrystallized, fluid. The separation of this fluid is the next process, and is perfected in the curing house, so called. This is a large building, with a cellar which forms the molasses reservoir. Over this reservoir is an open framework of joists, upon which stands a number of empty potting casks.
Each of these has eight or ten holes bored through the bottom, and in each hole is placed the stalk of a plantain leaf. The soft, concrete mass of sugar is removed from the cooling pans in which it has been brought from the boilers and placed in the casks. The molasses then gradually drains from the crystallized portion into the reservoir below, percolating through the spongy plantain stalks.
On the larger plantations, machinery of very elaborate description is used, and the most advanced processes known to science are employed in the manufacture. The principle is, however, the same as has been seen in the account of the simpler processes. On these larger plantations there are extensive buildings, quarters for workmen, steam engines, and all the necessary adjuncts of advanced manufacturing science. In the sugar mills the cut cane is carried in carts to the mill. It is then thrown by hand upon an endless flexible conductor which carries the cane between heavy crushers. The great jaws of the crushers press the cane into pulp, when it is thrown aside automatically to be carted away and used as a fertilizer. The juice runs off in the channels of the conductor into huge pans. The juice is now of a dull gray color and of a sweet, pleasant taste, and is known as guarapo. It must be clarified at once, for it is of so fermentable a nature that in the climate of Porto Rico it will run into fermentation inside of half an hour if the process of clarifying is not commenced. The pans into which the juice is conducted are pierced like a colander. The liquor runs through, leaving the refuse matter behind. It is then forced into tanks by a pump and run to the clarifiers, which are large kettles heated by steam. Lime is used to assist the clarification. It is then filtered into vats filled with bone black. The filtering is repeated until the juice changes color, when it is conveyed to the vacuum pans. It has now become a thick sirup. It is then pumped into the sirup clarifiers, skimmed, and again run through bone black, and finally is conducted into another kettle, where it is allowed to crystallize. The sirup that fails to crystallize is molasses, and it is here that we catch up with what we started after. To extract the molasses from the crystallized mass of sugar, we must go to the purging house. This is similar to the building spoken of in connection with the simpler process. It is of two stories. The upper floor is merely a series of strong frames with apertures for funnel-shaped cylinders.
The sugar is brought into the purging house in great pans, which are placed over the funnels. The pans are pierced with holes through which the molasses drains off into troughs which are underneath the floor, all running to a main trough. From thence the molasses runs into vats, called bocoyes, each of which holds from 1,200 to 1,500 gallons. The hogsheads in which the molasses is brought to this country are manufactured principally in Philadelphia and taken to the West Indies. They are placed in the hold of the vessel and the molasses pumped into them. The government standard for molasses is 56 degrees polarization. When not above that test, the duty is four cents per gallon. Above it the duty is eight cents. This tends to keep molasses pure, as the addition of glucose increases the quantity of sugar and therefore of the polarization, and would make necessary the payment of increased duties. The adulteration of molasses is therefore largely if not wholly done after it is out of bond and in the hands of the jobber.