Vol. IX. -Vo. 215. 



THE AGRICULTURAL NEWS. 



227 



rendered considerably more difficult, and it can hardly 

 be a matter for wonder that his advice is sometinn s not 

 directly suited to the requirements of the agriculturist. 

 Too much emphasis cannot be laid on the importance of 

 forwarding, with all specimens for examination, the full- 

 est possible account of all circumstances, however trivial, 

 that may shed any light on the problem, as in this way 

 only, can a full and sympathetic understanding of any 

 given case be arrived at, by his advisers, which will 

 enable the practical agriculturist to be in receipt of the 

 best and most carefully considered recommendations. 



THE MANUFACTURE OF WHITE SUGAR 



IN JAVA. 



An article with the above title, by E. C. Prinsen 

 Geerligs, appears in the International Sugar Journal 

 for June 1910 (Vol. XII, p. 285). The paper on which 

 it is based was read at the Paris Congress, and in view 

 of its interest, it is reproduced here. 



The production of white plantation sugar, destined for 

 direct consumption, has made enormous progress in Java 

 during the past few years. It was only in 1903 that Java 

 commenced to export to British India some thousands of tons 

 of this sugar; but the quantity produced in 190-5 was 70,000 

 tons, and in 1909 it reached 2.50,000; whilst now, many 

 factories are adapting their i)lant few the future manufacture 

 of the white product. 



Java white sugar has already turned out all the German 

 product on the Indian markets, and to a great extent all the 

 Austrian sugar. Nevertheless, the production of yellow sugars 

 has in no way suti'ered by the export of white, but has even 

 increased. In 1900, Java produced 700,000 tons of refining 

 sugar; in 1905, this increased to 900,000 tons, to amount to 

 1,000,000 tons in the past year. Whilst almost all the 

 factories have augmented their production, new ones have 

 also been constructed, with the result that the production of 

 the island has tripled during the past twenty years. In lS9Li, 

 the white sugar produced was only Isiier cent, of the total 

 turn-out, but now it has risen to almost 20 per cent, of the 

 total production. 



This white plantation sugar is made without retining, 

 and without the use of animal charcoal. Since it is to be 

 con.sumed in India, it must be free from contamination from 

 animal matter, this being prohibited by the Hindus by reason 

 of their religious sentiments. Moreover, this sugar is not 

 very white, and it is not to be compared to the white product; 

 but its buyers appreciate it, as its increasing consumption 

 fully testifies. 



The first factories taking up the manufacture of white 

 sugar in Java were specially equipped for the purpose. They 

 had carbonatation tanks, lime kilns, and indeed all the machin- 

 ery for clarifying and purifying the juice by the double car- 

 bonatation process. This method, although it gives a white 

 sugar of excellent <iuality, which behaves very well in the 

 tropics during storage and transi)ortation, is very costly to 

 make by reason of the expense of the limestone, of the coke, 

 and of the labour necessary for working the kilns. Further, 

 since carbonatation makes the juice very bright, it is imposs- 

 ible to turn out a refining sugar suitable for export to the 

 United States ami to Japan. In these two countries the 



Customs duties are higher for a sugar light m colour than 

 one that is darker, so that the buyer demands a dark sugar 

 with a high polarization. 



These two requirements may be satisfied by clarifying 

 the juice by ordinary defecation without filtration, but not 

 by clarifying by double carbonatation with filtration. It would 

 therefore be necessary to choose the method to be adopted: 

 whether all the factory is to be equipped for carbonatation, 

 and white sugar only made; or whether the manufacture of tlie 

 yellow sugar is to be continued, and the factory left as it is. 

 Some have advocated the purification of the juice by a more 

 eftective method than carbonatation, and have advised the 

 introduction of improvements in ordinary defecation so as to 

 allow of the manufacture of a whiter product. Thus the Ran- 

 son system was tried, and since this did not give the d(;sired 

 satisfactory results, a number of other orocesses were taken up. 

 The majority of these were worked secretly, but they have 

 gradually been given up, until now the manufacture of sugar 

 has entirely lost its mysterious aspect. 



The method of working at present in vogue in Java is 

 as follows: The mill juice is tempered in the cold with 15° 

 Beaume milk-of-lime at the rate of 5 to 6 litres for every 1,000 

 litres of the juice; then sulphur oven gases introduced until the 

 reaction is just neutral, which point is determined by phenol- 

 phthalein paper. This neutralized juice is nea*- passed 

 through the juice heaters, where it is heated to boiling point, 

 then into the defecators. After separating the impurities by 

 decantation, the clear juice is conducted to the evaporators, 

 whilst the subsided mud is sent through the filtertpfesses, and 

 the resulting clear liquor united with that in the evaporators. 



Then evaporation goes on until a density of 50° Brix^is 

 reached, after which boiling to grain follows, vWthout any 

 return of after-product. Sometimes the syrup is submitted 

 to a second sulphuring until it is very slightly acid, but 

 generally a simple decantation suffices. The massecuite is 

 machined, without being cooled, in a series of centrifugals. 

 The crystals obtained are not washed, but are taken out, 

 mixed with syrup, and machined in a second series of 

 centrifugals, being this time washed after all the covering 

 syrup has been spun out. Finally, the sugar is dried by a jet 

 of dry steam, discharged by the machines, allowed to cool in 

 the air, sieved, and bagged. 



The covering syrup is returned to the .syrup tank to be 

 subsequently drawn with the syrup into the pan. The centri- 

 fugalled molasses is diluted, sulphured, and boiled to grain; 

 its massecuite is run into crystallizers-in-motion in which it 

 is very slowly cooled, being diluted with water if it is not suffi- 

 ciently limpid. When quite cool, it is centrifugalled without 

 purging the sugar. The after-product obtained by this 

 operation is an exhausted molasses, which is rejected; whilst 

 the sugar, which contains a large amount of adhering 

 molas.ses may be treated in different ways. Some sell it as 

 molasses sugar; while others mix it with first jet massecuite 

 in crystallizing tanks. 



If the sugar obtained does not possess the desired white- 

 ness, the syrup in the pan may be decolourized by means of 

 hydrosulphite, and the sugar in the centrifugals be treated 

 with a little ultramarine, to give it a better appearance. 



The quality of the sugar produced by the method 

 described does not at all ditler from that obtained by carbon- 

 atation ; it is just as white and preserves its colour as well, 

 but sulphitatiou has the advantage of great simplicity. 



All the plant for the manufacture of raw sugar may be 

 retained, and it is only necessary to add a sulphur oven, the 

 requisite piping, and a few centrifugals to make white sugar. 

 Then, either white sugar or the raw product may be manufac- 

 turer!, according to the conditions obtaining on the market. 



