Maguey-sugar is derived from the sap of the maguey-plant (_Agave Americana_). It is much used in Mexico and the Central American states. The method of manufacture is very crude and the product is not exported. Palm-sugar is obtained from the sap of several species of palm growing in India and Africa. =Sugar Manufacture.=--Sugar manufacture includes three processes--expressing the sap, evaporating, and refining. The first two are carried on at or near the plantations; the last is an affair requiring an immense capital and a most elaborately organized plant. The refining is done mainly in the great centres of population at places most convenient for transportation. The raw sugar may travel five or ten thousand miles to reach the refinery; the refined product rarely travels more than a thousand miles. After it has been cut and stripped of its leaves the sugar-cane is crushed between powerful rollers in order to express the juice. The sugar-beet is rasped or ground to a pulp and then subjected to great pressure. The expressed juice contains about ten or twelve per cent. of sugar. In some factories the beet, or the cane, is cut into thin slices and thrown into water, the juice being extracted by the solvent properties of the latter. This is known as the "diffusion" process. The juice is first strained or filtered under pressure in order to remove all foreign matter and similar impurities. It is then clarified by adding slacked lime, at the same time heating the liquid nearly to the boiling point and skimming off the impurities that rise to the surface. The purified juice is then boiled rapidly in vacuum pans until it is greatly concentrated. When the proper degree of concentration is reached, the liquid is quickly run off into shallow pans, in which most of it immediately crystallizes. The crystalline portion forms the _raw sugar_ of commerce; the remaining part is molasses. The whole mass is then shovelled into a centrifugal machine which in a few minutes separates the two products. In purchasing raw sugar, the refiner was formerly at a loss to know just how much pure sugar could be made from a given weight of the raw sugar. In order to aid in making a correct determination, the Dutch government formerly prepared sixteen samples put up in glass flasks and sealed. These samples varied in color according to the amount of pure sugar contained. The pure solution was known in commerce as No. 16 Dutch standard, and this was generally taken all over the world as the standard of pure sugar. Within recent years the polariscope, an optical instrument that determines the percentage of sugar by means of polarized light, has largely replaced the Dutch standard.