SUGAR BOILING AND CRYSTALLIZATION-IN-MOTION 393 



was not till a little before 1900 that attention began to be paid to them in 

 the cane sugar industry, where the pioneer work was done in Java. At first 

 crystallization-in-motion was applied to grained products. A grained 

 massecuite was discharged from the pan into a receiver and cooled for 

 several hours in motion, with the result that the sugar in supersaturated 

 solution deposited on the crystals, whereas if cooled at rest this sugar would 

 separate out as very fine individual crystals, which would not be capable of 

 immediate recovery. This scheme, while giving an enhanced recovery of 

 first product and eliminating one or more stages in the system of repeated 

 boilings, could never avoid the necessity for boiling low-grade products 

 with the presence of the accompanying low-grade sugars, the disposal and 

 marketing of which is so difficult. The next step, which also originated in 

 Java, was the attempt to obtain all the sugar in one operation, and was known 

 as the " First sugar and molasses process." To do this it would be necessary 

 to reduce the purity of the massecuite en masse to at least 65 purity without 

 any previous separation of crystals. Accordingly, the syrup massecuite was 

 boiled very thick and was then mixed in the pan with exhausted molasses 

 until the predetermined purity of the strike was obtained. After cooling 

 in motion, if everything had gone well, first sugar and exhausted molasses 

 resulted, a part of which were removed from process, and a part retained for 

 subsequent operations. It was, however, very hard to obtain marketable 

 sugar from these strikes, and eventually the process was abandoned. After 

 much experimentation, however, schemes have since been developed whereby 

 the low products are entirely suppressed, and the juice is separated into a 

 marketable sugar and waste molasses within 96 hours of its extraction from 

 the cane. These processes are described below. Accumulated experience 

 has shown that a massecuite of 55 to 60 polarization gravity purity when 

 boiled to the proper water content and cooled in motion for about 60 hours 

 can be separated into a medium grade sugar and waste molasses. By wash- 

 ing, the crystals can be made of 96 test, but in practice no attempt is made 

 to thus treat them. 



The best method of obtaining them as marketable sugar is that devised 

 by Spencer at Tinguaro, in Cuba. In this scheme the crystals are dropped 

 wet from the centrifugals, mingled with molasses from a high-grade strike, 

 and pumped to the tanks wherein is the high-grade massecuite with which 

 they are cured, and with the sugar from which they appear as marketable 

 product. Alternatively the sugar may be used as seed grain or be remelted, 

 either of which schemes is inferior to the one described above. In actual 

 practice one of two routines is followed, known as a two or a three-massecuite 

 process. 



Two-Massecuite Process. The polarization gravity purities selected are 

 75 for the first product and 55-60 for the second. On commencing 

 operations, a strike is boiled from syrup alone and separated at once into 

 crystals and molasses. The latter are taken back into the pan with syrup 

 in such quantity as to give a mixed strike of 75 purity. From this with 

 efficient boiling molasses of 45 purit}' will result. From now on every strike 

 of syrup massecuite is reduced to this test by the addition of the circulating 

 45 test molasses. As the routine continues the 45 test molasses increases 

 in quantity, and when enough has accumulated a strike of 55-60 test is 

 boiled. This is discharged into crystallizers and cooled in motion for about 

 60 hours, when the temperature should have fallen to about 100 F. On 

 drying this material it should separate into a sugar and exhausted molasses 



