consists of three rollers the same as the first mill but sometimes only two. Occasionally a third is used. It is quite customary to sprinkle the crushed cane as it comes from the first mill with water before it enters the second mill, thus securing a greater degree of extraction. The residue from the mill is called bagasse and is commonly carried directly to the furnace and used as fuel, furnishing steam, to evaporate the juice and drive the mill. The mills extract from 75 to 80 percent of the weight of cane in juice. The sugar cane contains about 88 percent of its weight of sugar juice. It is seen, therefore, that a considerable portion of the sugar remains in the bagasse. By the process of diffusion a larger proportion of the sugar is extracted than by milling, but the resulting juices are very much diluted and require a greater combustion of fuel for evaporation.
Clarifying the Juice.—The juice as expressed from the cane is a dirty-looking mass and requires to be clarified before it is concentrated. It is a very common practice to subject the fresh juice to the fumes of burning sulfur. In all cases the first step in the clarifying is the addition of lime to neutralize the natural acidity of the juice and facilitate the coagulation of the dissolved matter. The limed juice is next subjected to heating and as the boiling point approaches a separation of the suspended and coagulated matter takes place, the light coming to the top and the heavy falling to the bottom. The common method of separating these bodies is by skimming the top coagulum and settling the bottom portion and drawing off the clear juice therefrom. In addition to this to get a more complete separation the heated juice may be run through a filter press.
The clarification of sugar cane juice, as is seen, is much more simple than that of beet juice. The method employed for the clarification of beet juice is sometimes used for cane juice but not very frequently.
Evaporation of Clarified Juice.—After the clarification is completed the further treatment of the juice is exactly the same as that for the sugar beet.
Manufacture of Maple Sugar.—The maple trees in the United States grow chiefly in the New England states, especially in Vermont, New York, Ohio, and Indiana. Very little sugar is made in other states. The season of manufacture is at the beginning of spring, when the sap first begins to run and before the buds of the new leaves have developed very extensively. The season lasts from four to six weeks. In New England it begins the latter part of March and in Ohio and Indiana in February. The trees are bored and a tubular spile driven into the wood through which the sap escapes into the bucket or other receptacle. Figs. 77, 78, and 79 are typical scenes in a small maple orchard during the season, showing tapping of the trees and collection and boiling of the sap. The sap of the maple tree is extremely bright and clear and requires no clarifying. It is usually evaporated in open kettles or pans, the vacuum process not being employed. The crystallization
