202 



SUGAR, 



a montjus into copper clarifiers with double bottoms, heated by steam at a pres- 

 sure of five atmospheres. To every hundred litres of juice (=22 gals.) two 

 kilogrammes of lime are added (about four and a half pounds English weight). 

 The lime is most carefully prepared and mixed with large quantities of hot 

 water till it forms a milk perfectly free from lumps. The steam is turned ofi", 

 and the juice heated to 90 deg. A complete defecation has taken place, the 

 steam is shut off, and the juice left a short time, to allow the heavier impurities 

 to subside. It is then run off in the usual manner, undergoes a slight filtration 

 through a cotton cloth placed over a layer of about four inches thick of animal 

 charcoal, and runs into a second set of copper vessels placed on a lower level 

 than the clarifiers ; these vessels are heated by means of a coil of steam piping 

 sufficient to make them boil. A second pipe passes into them, making a single 

 turn at the bottom of the vessel ; this is pierced on the lower side with small 

 holes, through which a stream of carbonic acid gas is forced. 



This decomposes the saccharate of lime, which has been formed in conse- 

 quence of the large excess of lime added to the clarifiers. 



The lime is precipitated as carbonate. When precipitation has ceased, steam 

 is turned on, and the whole made to boil ; this expels any excess of carbonic 

 acid ; the liquor is then run off, undergoes a similar partial filtration to that 

 mentioned above, and is then passed through the charcoal filters to be decom- 

 posed. The sugar made by this process, directly from the beet-root juice, is 

 nearly white. The molasses is re-boiled as often as six times ; each time under- 

 going a clarification and filtration through animal charcoal. And the proceeds 

 of the last re -boiling is certainly in appearance not worse than a great deal of 

 muscovado I have seen shipped from Trinidad. 



In this work there are about 150 people employed. The work goes on night 

 and day, one gang replacing the other. The whole evaporation is done by two 

 vacuum pans, each 6~ feet in diameter, 80,000 kilogrammes of beet-root are used 

 daily, from which about 6,000 kilogrammes of sugar are obtained, equal to about 

 6 tons English weight. 



In these and every other works I visi ted — eight in all — the centrifugal ma- 

 chines wore in use, and had in most cases been so for two years ; those lately 

 made have been much simplified in construction, and work admirably. Cail & 

 Co., of Paris, are the makers ; their charge is 3,000 francs for each machine 

 (£120 stg.). They require about one and a half horse power each. As they are 

 wrought in France, one machine is about equal to work off a ton and a half of 

 sugar daily, working all the 24 hours. Mr. Cail recommends a separate engine 

 for those machines ; so that they can be used at any time, independent of the 

 other machinery. The charge put into a machine is about 80 kilogrammes, from 

 which about 30 to 35 kilogrammes of dry sugar is obtained ; the calculation is, 

 I believe, 40 per cent. I weighed some of the baskets of sugar taken out after 

 drying, and found them 35 kilogrammes. Sugar intended for the machine is 

 never concentrated beyond 41 degrees Baume ; that made from the juice direct 

 is allowed 18 to 34 hours to crystallize, and is put into the machine in a semi- 

 liquid state ; the motion at first is comparatively slow ; in about three minutes 

 the sugar appears nearly dry ; about three-fourths of a gallon of brown syrup is 

 then poured into the machine whilst in motion, and the speed brought up to its 

 highest, about 1200 revolutions a minute ; in 3 or 4 minutes more the machine 

 is stopped, the sugar scooped out and thrown into baskets, the inside of the re- 

 volving part, and especially the wire cloth, carefully washed v/ith a brush and 

 water, and a fresh charge put in. The whole time betwixt each charge is about 

 15 minutes. From the large proportion of molasses you will see very plainly 

 that those who do not intend to re -boil, need not think of centrifugal machines. 

 The sugar dried in this way is not altogether white, but has a slight greyish 

 yellow tinge. 



Of the other sugar works which I visited, the only one of peculiar interest was 

 that of Mr. Dequesne, near Valenciennes. Here the roots are first cut into smaU 

 pieces by an instrument similar to a turnip slicer, then dried in a species of 

 kiln, and stored up till required. In this way I was told beet-root could be 

 preserved with very little deterioration for a full year, and this enables Mr. De- 

 quesne to go on making sugar all the year round. "When the sugar is to be ex- 



