SUGAR CANE 61 



which would economically harvest cane and save a great part 

 of the hand labor required in this operation. Cane is therefore 

 cut with a cane knife and is carried to the mill in special cane 

 cars on permanent or portable tracks, in water flumes, by ox 

 carts, in canals, especially in Demerara and Straits Settlements, 

 or on aerial cables. 



In most modem sugar mills cane is crushed and the juice is 

 expressed in three-roller-units. In each unit the rollers are so 

 placed that their centers are at the angles of an isosceles tri- 

 angle. The rollers are commonly 30 by 60 inches, or 34 by 78 

 inches, are made of steel, and are variously grooved and 

 ridged. Sugar mills may be 9, 12, or 15 roller mills, that is, 

 contain a series of 3, 4, or 5 three-roller-units. These 

 rollers are often preceded by a forced feeding device and a 

 shredder or crusher. It has been found in Hawaii that a 12- 

 roller mill with rollers 30 by 60 inches would treat 50 tons of 

 cane per hour. The pressure on the upper roller varies from 

 200 to 400 tons in different mills and the surface of the rollers 

 revolves at a speed of 16 to 25 feet per minute. 



Another method for extracting sugar is the diffusion process. 

 This process depends upon the principle of osmosis. The 

 method has been adopted on many plantations in different 

 countries and is still in operation. In extracting sugar by 

 this method cane is cut into thin slices about 1-20 inch thick. 

 The juice is then allowed to diffuse into pure water or into 

 dilute juice in a series of vessels. While this method, as 

 just stated, is still in use, it is for the most part in operation 

 only on small plantations. At the annual meeting of the Ha- 

 waiian Sugar Planters' Association in November, 1915, some 

 interest was manifested in experiments with this method in 

 Hawaii and one manager stated that a large plant would soon 

 be installed to give the method a thorough test. 



By the usual process of sugar extraction, the juice from the 

 crushed cane is at once heated to a temperature of 190° to 

 200° F. to clarify it. Lime is added to the juice at the same 



