and the time occupied in purging a charge of 300 lb. sugar is 40 to 50 minutes. Raw sugar containing about 80 per cent. of crystallizable and 6 per cent. uncrystallizable would yield about 50 per cent. of sugar in hard blocks, of a dirty grey appearance, polarizing say 96 per cent., but containing a considerable proportion of the mineral impurities, with probably not more than I per cent. of uncrystallizable; the remainder of the crystallizable sugar has been melted by the action of the steam, and carried into the molasses. This process is at work in the refinery of James Duncan, for purifying beet sugars, and at the Oriental Refinery, Hong Kong.

Where raw sugars are prepared by melting and graining in the vacuum-pan, and passed through this machine previous to being refined by charcoal in the manner already described, it is necessary to first grain in the vacuum-pan, otherwise the objections to the process when used for soft sugars, already urged, hold good. Of course, the larger the crystals, the less time does it take to purify, and consequently the greater the yield. Refining by successive crystallizations is of little or no value. It is carried out by melting the sugar, boiling for grain, centrifugaling, and reboiling the successive syrups. Only three crystallizations can be obtained by this plan, and the third is almost as bad if not worse in colour than the

original sugar. About 50 per cent. of the total sugar is obtained from the first masse-cuite, 16 to 20 from the second, and 8 to 12 from the third, the molasses being fit for nothing except distilling.

CHAPTER XX.

THE CENTRAL FACTORY SYSTEM.

As a general rule in the cane sugar industry, each canegrower also works up his own sugar and rum; but there are important exceptions to this rule, where the planters of a district send their canes to a central factory to be dealt with. This system seems to have originated among the French beet farmers, and has been thus introduced extensively into the cane-raising French colonies. It has been adopted on a much smaller scale by British colonists in Natal and elsewhere, and appears to succeed pretty well in Brazil. Nevertheless it must be confessed that the system has been brought to greatest perfection under French management in Martinique and Guadeloupe.

The largest central factory or usine in the French West Indies is the Usine d'Arboussier, situated in the suburbs of the seaport of Point-à-Pitre. It is constructed upon the grandest scale. The cost was 216,000l., and the usine is equal to an out-turn in the first 6 months of the year of 8000 to 10,000 tons of sugar. The supply of canes is derived from both divisions of Guadeloupe, the volcanic and calcareous. From the former, they are conveyed in large lighters towed by steam-tugs; from the latter, by the tramway, several miles in length. The canes are carted by the planter to his nearest point on the railway or shore, and thence by the usine to their destination, where they are weighed by a sworn agent in the presence, if required, of a representative of the estate. The planter receives 5 per cent. of the weight of his canes of conne quatrième, equal to No. 12 "Dutch Standard," the price being

regulated by the market at Point-à-Pitre at the time the canes are delivered.

The process of sugar manufacture at this usine is as follows. The canes are brought by the planter to a siding of the main tramway on his estate. The waggon generally carries 2 tons of canes, and a mule on a good level ordinary tramway can draw easily 2 waggons. The waggon, when brought to the mill itself, conveys the canes to the rollers, the begass being elevated by power to a platform over the boilers. The juice on leaving the mill-bed falls through 3 strainers into a tank which has a double bottom heated by steam. It is treated here with a little bisulphite of lime, and is then run into a monte-jus, which sends the juice up to the clarifiers, where it is heated in the ordinary way, and tempered with lime. From this, it is passed to the charcoal filters, through which it gravitates, and thence by a gutter into a receiver, to be forced up into a cistern over the triple-effect. From this cistern, it flows into the triple-effect, passing from the first to the second and from the second to the third boiler, as the attendant wishes.

When it leaves the third boiler, it is, generally speaking, at 25° B.; it is immediately passed through new charcoal, and falls into another receiver, whence it goes to the vacuum-pan. The first quality sugar is generally crystallized in the pan, and is then dropped into sugar-boxes which stand 7 feet from the ground; under these boxes, a little charging vessel runs on a railway that is hung from the bottom of the boxes, and this vessel conveys the sugar over the centrifugals, where it is cured; the molasses from this is boiled up, when found in good condition, with the syrup of the following day. When these molasses are thick and clammy, they are boiled by themselves and dropped into sugar-boxes, where they are allowed to granulate for a number of days. This makes the second quality of sugar; the molasses from this, along with the skimmings and subsidings of clarifiers, goes to make rum.

The juice that leaves the clarifiers does not pass over fresh charcoal, but follows the syrup from the triple-effect, thus assisting to wash out the sweets which may have been left by

the syrup.

The following figures show the weight of canes delivered to the factory in the 4 years commencing 1869:—

17,808,217 kilogrammes (about 1000 kilo. equal 1 ton.)

This factory pays 5 per cent. for its canes, and the figures following show the financial results for the 3 years ending

A profit of 7000l. was expected in 1870. Severe losses sustained on produce shipped, owing to failures during the Franco-German War, are assigned as the reason for the failure of profits at the usine in 1870.

In 1870, 6096 boucauts of sugar of 500 kilos. each, equal in round numbers to 3000 tons, were obtained from the 42,808 tons of canes received, or 7 12 per cent. of sugar; 3 per cent. of syrup was also obtained, which was converted into 470,486 litres, equal to 117,620 gallons of rum, of an average centigrade strength of 60°, equal to 3981 gallons per ton of sugar.

In 1871, 10,651 boucauts of sugar, or 5325 tons, were obtained from the 68,745 tons of cane received, or 7'74 per cent., composed as follows:-First quality sugar, 6·24 per cent.; second and third quality, 150 per cent. A minimum

average return of 8 per cent. is confidently expected when not less than 25 per cent. of plant canes are regularly forwarded from the contributory estates to the factory.

This usine in April 1872, the third year of its existence, declared a first dividend of 24 per cent., exclusive of 4 per cent. carried to the "Sinking Fund Account." The general manufacturing and working expenses in 1871 amounted to 2,394,298 francs, or 117,732. The sugar realised 3,543,867 francs, or 141,7547.; the proceeds of rum were 306,894 francs, or 12,2757; equal together to 154,0297, showing a profit upon a simple debit and credit account (without charging interest upon capital, wear and tear of stock, &c.) of 36,2971. upon a manufacture of 68,745 tons of sugar and 182,798 gallons of

rum.

The processes of manufacture both of sugar and rum in all the usines, both in Martinique and Guadeloupe, are more or less identical, the only perceptible difference being the adoption in new factories of modern and improved appliances. The clarification of the juice, its reduction to syrup at a low temperature, the perfect crystallization and good colour of the sugar, and a maximum return, are obtained by repeated filtration through animal charcoal, the triple-effect and vacuumpan processes, and centrifugal machines.

A small private usine called Beauport, not far from Pointà-Pitre, purchases canes from the neighbouring estates, paying 6 per cent. for them, and upon a manufacture of 2000 tons of sugar per annum the clearances are very handsome. The books show a return of 19,400/. upon 59,963,371 lb. canes purchased (1868). These figures indicate a profit of about 14s. 6d. per ton of canes purchased. The quantity of sugar made in 1868 was 2600 tons, and 62,700 gallons of rum, or a return of about 210 lb. of sugar and 1 gallon of rum per ton of canes manufactured.

The Usine Cluny is in general respects similar to that of Beauport, and canes are brought by water in punts from a