The sap of the cane must be extracted by crush ing and rolling, then condensed by evaporating the water it contains, then clarified and crystal lized into the sugar of commerce.
The best mills get 95 per cent. of the sucrose (sugary content) of the cane. This process begins with the carrier that brings a continuous supply of cane to the shredding knives. The torn fibres go to the crushing rollers, a series of them, that finally leave the dry fibre, called "bagasse" in America. This is burned in the furnaces for fuel, or saturated with the sweet residue of the sugar vats, and sold as a cattle food under the trade name, "molascuit." A recent use for the fibre is as a filtering material for the clearing of the liquid sugar.
Vacuum pans rarefy the air so that the contents boil at a low temperature, which is the only way to keep all the sucrose in the chemical state to crys tallize when the proper degree of condensation is reached. When crystals begin to form in the pan, the process goes forward rapidly, and the mass is quickly cooled, and the crystallized sugar, in a small amount of liquid, is let out into centrifugal separators, with fine metal gauze in their linings. These vessels revolve at high speed, and the molasses flies out through the screens, while the granulated part of the sugar remains behind. It is just as we see it in the markets. If the molasses is not all thrown off, we have a moist sugar, in stead of the granulated, dry kind.
Molasses is made by heating the cane juice to a temperature that converts much of the sucrose into "invert sugar," a form that will not crystal lize. So sweet and rich is the syrup that it has great food value, and is one of the valuable by products of sugar making, in all the old processes. Only the vacuum pan prevents the formation of invert sugar, and the molasses resulting from this process is almost worthless as food. The fer mentation of this low-grade molasses produces alcohol fit only for industrial uses. The rich molasses, diluted with water and fermented, pro duces rum.
By the name, Sorghum, we in America mean the sugar-bearing variety of the species, sorghum, which is big enough to include the broom corn and the kafir and durra, inaccurately called corn and millet.
The hard times that kept farmers poor in the West thirty or forty years ago, made sugar a luxury that they could not afford. The plant upon which a good deal depended in those times was the "amber sorghum," from which sorghum molasses was made. Every farmer planted a small patch of cane, and when the slender stalks had ripened their feathery panicles of flowers, they were stripped where they stood. Then they were topped, after being cut down, and the part that contained the soft pith, saturated with sugar, was hauled to the mill. This was a crude affair, installed by a neighbor who ground and boiled for the community, if he could spare the time. A crusher consisted of steel cylinders between which the canes were fed, while a horse went round and -round to furnish the power. The sap was caught below the crusher, and conducted to a reservoir, or directly to the evaporating pan, under which a fire burned, while the man attending it skimmed the boiling liquid to get rid of the im purities in it. Eight gallons of juice made one of heavy syrup. The strong taste was partly due to the leaf fragments and other foreign matter that made 25 per cent. of the crude sap.
To-day, cheap glucose syrups have replaced the molasses of frontier memory. But they are not so honest as the darker, heavier molasses. The gingerbread and molasses cookies of our grandmothers' day cannot be equalled by any present-day treacles. The farmer affords sugar now, and therefore the manufacture of molasses has fallen off in country districts, and the crushers rust in the junk heap.
This sorghum came originally from Africa by way of Egypt, and an importation of seeds brought it also from China, to be tried as a fodder plant in drought-stricken regions of the Southwest. Here it is still grown for forage and for syrup. Half grown canes are pastured and made into silage. It out-crops the best varieties of fodder corn.