BEET SUGAR.

461 has probably not exceeded eight tons per acre, while the average yield in Europe is twelve or thirteen tons per acre. In this respect the Louisiana sugar cane has a marked advantage, the average crop being over twenty tons, while thirty and even forty tons are often obtained. As soon as our farmers learn the principles of culture it is certain that the average yield in the United States will be as great as that in Europe. A typical field of beets ready for the harvest is shown in Fig. 70.

Manufacture. The manufacture of beet sugar is both a simple and a complicated operation. The simplicity of it consists in the fact that it is only necessary to extract the saccharine juices of the beet, properly clarify

them, and reduce them by evaporation to a point where the sugar will crystallize. In reality the operation of successful manufacture requires elaborate and costly machinery and a high degree of technical skill. A brief outline. of the method will be sufficient for the purpose of this manual.

The beets, after harvesting, have the tops cut off with a small quantity of the adhering material of the neck of the beet, which contains large quantities of salts and is not suitable to enter the factory. In Fig. 71 is shown a view of a beet field after the harvest. The beets are then thoroughly washed and passed through a slicing machine in which they are cut up into thin slices or ribbons. They then enter a series of tanks, known as a diffusion battery, in which they are thoroughly treated with hot water, by means of

which practically all of the sugar which they contain is extracted. The saccharine product obtained, known as the diffusion juice, is treated with a

FIG. 72.-DIFFUSION BATTERY.-(Farmer's Bulletin 52.)

large excess of lime, heated, and carbonic acid derived from a lime kiln blown through it until the lime is all converted into a carbonate carrying down with

BEET SUGAR.

463 it the impurities of the juices. The diffusion juice as it comes from the diffusion battery is usually almost as black as ink. After carbonatation, as the process above is called, it is of a clear, light amber tint. To separate the liquid from the solid matter the whole is passed through a filter press from which the juice emerges bright and clear and the carbonate of lime with its adhering impurities remains in the filter press as hard cakes. This process is repeated in order to secure as great a purity as possible in the juice.

Evaporation.-The purified juice is conducted into multiple-effect vacuum pans, Fig. 73, from which the air is partially exhausted by a pump, the vacuum rising in the series. There are usually three or four of these pans connected to

FIG. 73.-MULTIPLE-EFFECT EVAPORATING APPARATUS.-(Farmers' Bulletin 52.)

gether, the first one having the least air exhausted from it and the last one the most, that is, having the highest vacuum. The vapor which arises from the first pan is conducted through the copper coils to the second and serves as the heating agent while the vapor from the second pan passes through the copper coils to the third and so on to the fourth. Thus the steam used for evaporating is turned only on the first pan and by this means a great economy in the use of fuel is secured. In this way the juice is evaporated to a sirup. This is usually somewhat colored and if white sugar is made it is bleached by passing through bone-black or by the application of sulfur fumes. When sulfur is used it is often applied first to the unevaporated juice as well as to the sirup.

Final Crystallization. The sirup is now ready for the final process, which takes place in what is known as the vacuum strike pan, Fig. 74. A considerable quantity of sirup is introduced so as to cover the lower coils of this pan and, after the vacuum is established by a pump, evaporated to the crystallizing point. An additional quantity of cold sirup is then drawn into the pan, chilling the mass and thus producing incipient crystallization in the form of extremely minute crystals. The evaporation is now continued with the addition of sirup from time to time, by which process the sugar crystals begin to grow. In the course of a few hours the pan is full of crystals of the size desired. Purification of the Sugar.-The vacuum is broken and the crystallized

mass of sugar drawn into a mixing apparatus whereby all lumps are broken up and a uniform magma secured. Thie is done while the mass is still warm. Were it allowed to cool it would be extremely difficult to break it up. The warm mixture is then passed into the centrifugal machine, by means of which the molasses is separated from the crystals and these remain as white pure crystals in the pan. The whole process of separating the juice from the massecuite, as the mass is called, occupies only a few minutes. Thus the sugar is often centrifugalled and in the barrels before it is cold from the vacuum pan.

MANUFACTURE OF CANE SUGAR.

465

The above is merely the outline of a method which requires complicated apparatus, often of extensive proportions, and which could not be described in detail except in a technical work. It gives the reader, however, an idea of how the white sugar which he eats is made. Often white sugar is not made at the sugar factory, in which case the bleaching with bone-black, etc., is omitted. and a brown sugar is produced which afterward goes to the refinery.

FIG. 75.-SUGAR CANE FIELD READY FOR HARVEST.-(Photographed by H. W. Wiley.)

Growth of Sugar Cane.-The growth of sugar cane is confined to tropical and subtropical regions. In the United States this crop is grown chiefly in Louisiana and Texas. Its cultivation does not extend northward beyond. the center of Georgia. Typical scenes in sugar cane fields are shown in Figs. 75 and 76.

Manufacture of Cane Sugar.-In the manufacture of sugar from the sugar cane the first process, naturally, after the harvest, is the expression of the