W7 SUGAK CULTURE AND MANUFACTURE. 



SUGAR CULTURE AND MANUFACTURE. 



833 



purified by boiling it with water, with the addition of an alkaline sola 

 tioo and a quantity of milk. When this lias been continued until 

 ram no longer rises upon the liquor, it ia evaporated, and sometimes 

 trained, and afterward* transferred to earthen pots or jam. After it 

 ha* bran left for a few day* to granulate, holes in the pota are unstopped, 

 and the molasses drain* off into vowels placed to receive it. The 

 tugar i* rendered mill purer and whiter by covering it with the moist 

 leave* of some succulent aquatic plant, the moisture from which draiiif 

 slowly through the sugar, and carries with it the dark-coloured 

 molasses. A similar process to the above is laid to be practised in 

 Cochin China. 



The separation of the sugar from the cane-juice is effected in a much 

 simpler manner in the West Indies. The juice is conducted by gutters 

 from the mill to large flat-bottomed pans, called dar(Hert. Each of 

 these is placed over a fire, which may be regulated or extinguished by 

 a damper ; and each is supplied with a stop-cock or siphon for drawing 

 off the liquor. \\ 'lien the clarifier is filled with juice, a little slaked 

 lime is added to it ; the lime, which is called temper, being, in most 

 rnsca, previously mixed with a little cane-juice to the consistence of 

 cream. A* the liquor in the clarifier becomes hot, the solid portions 

 of the cane-juice coagulate, and are thrown up in the form of scum. 

 The proper heat is indicated by the scum rising in blisters and break- 

 ing into white froth, which commonly happens about forty minutes 

 after the fire is lighted. The damper is then closed, and the fire dies 

 out ; and after an hour's repose, the liquor is ready for removal to the 

 first of the evaporating pans. 



From the clarifier the purified juice, bright, clear, and of a yellow 

 wine colour, is transferred to the largest of a series of evaporating 

 pans, three or more in number. These evaporators are placed over a 

 long flue, heated by a fire at one end, over which the smallest of the 

 coppers, called the ttarhr, is placed. In the process of boiling, impuri- 

 ties are thrown up in the form of scum, which ia carefully removed. 

 In the tear/if, the liquor is boiled down to as thick a consistency as is 

 considered necessary for granulation ; this point being most commonly 

 ascertained by observing to what length a thread of the viscid syrup 

 may be drawn between the thumb and finger. This trial by the touch, 

 whence the teache is supposed to derive its name, is very imperfect ; 

 for it sometimes happens that the syrup may have the required tenacity, 

 and yet not be in a good state for crystallising. The latter point may 

 be better ascertained by observing the incipient granulation of the 

 syrup on the back of a ladle dipped in the teache. The thermometer, 

 though useful, will not be a sure guide in determining the proper 

 moment for striking, or emptying the teache ; because a viscous syrup, 

 containing much gluten and sugar, altered by lime, requires a higher 

 temperature to enable it to granulate than a pure saccharine syrup. The 

 concentrated syrup is ladled, or skipped, from the teache, either imme- 

 diately into open wooden boxes called coolers, or into a large cylindrical 

 cooler, from which it is afterwards transferred to the granulating vessels. 

 In these the sugar is brought to the state of a soft mass of crystals, 

 imbedded in thick, viscid, but uncrystallisable fluid. The separation 

 of this fluid is the next process, and is performed in the curing-house. 

 This is a large building, the floor of which is excavated to form the 

 molasses reservoir. Over this cistern is an open framing of joists, 

 upon which stand a number of empty polling-casks ; each of these has 

 eight or ten holes bored through the lower end, and in each hole is 

 placed the stalk of a plantain-leaf. The soft concrete sugar is removed 

 from the coolers into these casks, in which the molasses gradually drains 

 from the crystalline portion, percolating through the spongy plantain- 

 stalks. 



When it leaves the curing-house the sugar is packed in hogsheads 

 for shipment as ran; brown, or muscovado su;jar ; and in this state it is 

 commonly exported from our West Indian colonies. As the molasses 

 is very imperfectly separated from the crystallised sugar, a considerable 

 diminution of weight takes place subsequent to the shipment, by 

 the drainage from the hogsheads. This waste has been estimated to 

 amount to no less than 12 per cent. The loss upon French colonial 

 sugars used to be much greater even than this. Means have, however, 

 been adopted of late years in some colonial sugar-works for reducing 

 this loss. 



Clayed tugar, also called Lislan tugar, is raw sugar that has been 

 subjected to a peculiar operation. The sugar is removed from the 

 coolers into conical earthen moulds called forma, each of which has a 

 small hole at the apex. These holes being stopped up, the formes are 

 placed, apex downwards, in other earthen vessels. The syrup, after 

 being stirred round, U left for fifteen or twenty hours to crystallise. 

 The plugs ore then withdrawn, to let out the uncrystallised syrup; 

 and, the base of the crystallised loaf being removed, tie forme is filled 

 up with pulverised white sugar. This is well pressed down, and then 

 a quantity of clay mixed with water is placed upon the sugar, the 

 formes being put into fresh empty pots. The moisture from the clay, 

 filtering through the sugar, carries with it a portion of the colouring- 

 matter, which is more soluble than the crystals themselves. When 

 the loaves are sufficiently purified to be removed from the formes, 

 they are dried gradually in a stove, and crushed into a coarse powder 

 for exportation. Claying is little practised in British plantations, from 

 an opinion that the increase of labour and diminution of quantity of 

 produce occasioned by it are not compensated by the improved quality 

 of th<; sugar. It was however very generally practised by the French in 



St. Domingo. Hague's process consists in submitting the raw sugar, 

 after being cured in the usual way, to the action of a vacuum filter. 

 The apparatus consists of a shallow vessel, beneath which is a ravity 

 connected with nil air-pump. The bottom of the vessel is perforated 

 with a number of small holes ; and when a quantity of muscovado 

 sugar, mixed with a little water into a pasty mass, ia laid in it, upon a 

 piece of haircloth, the air is withdrawn from the cavity beneath the 

 sugar. The pressure of the superincumbent atmosphere upon the 

 surface of the sugar then drives the moisture, and with it much of the 

 colouring-matter, through the holes in the bottom of the vessel When 

 the sugar is sufficiently whitened, the air-pump is stopped, the sugar 

 and molasses are removed, and a fresh charge of muscovado is applic 

 Another means of avoiding the loss consequent on the drainage from 

 raw sugar during its voyage to this country, is the importation of 

 sugar for the use of the refiner, in the form of concentrated cane- juice, 

 containing nearly half its weight of granular sugar along with more or 

 less molasses, according to the care taken in the boiling operations. 



Before proceeding to the subject of sugar refining, it may be well to 

 make a few observations on suggested improvements in the Went 

 Indian treatment of raw sugar. Chemists, and the better class of 

 sugar-growers, liave long known that a large amount of sugar is wasted 

 by an imperfect management of the operations at the plantations. It 

 is believed that 25 per cent, of the juice lodges in the cells of the 

 megass or trash, and is lost ; it ought to be extracted, but is not. 

 Even if not, the trash might form a better fuel for the boiling-houses 

 (where it is now used) if first dried by the surplus heat of the 

 chimneys, &c. Dr. Scofferu, in 1847, ascertained that, in various ways, 

 no less than two-thirds of the sugar is in some instances lost. In IS 49 

 he introduced certain improvements, intended, by the use of new 

 defecating agents, to increase the quantity of juice obtained from the 

 cane, and of sugar obtained from the juice. Some of the agent 

 by him are poisonous however in their natural state, though innocuous 

 in the process ; and this seems to have retarded the acceptance of his 

 method. Some inventors say that the weight of juice extracted is 

 only 50 per cent, of the weight of the original cane, whereas it ouu-ht 

 to be 90 per cent. ; and they have devised a mode of treating the 

 megass with hydraulic pressure, after the mill has done its work ; by 

 this means the megass becomes a flattened mass of trash, as hard anil 

 nearly as dry as a deal board. It is also believed that, by a better con- 

 struction and management of apparatus more sugar and lejs molasses 

 [MOLASSKS] might be obtained from a given weight of juice. 



Sugar-trash has been tried in England as a material from which to 

 make paper, but without much success. 



Sugar-refining. Raw or muscovado sugar, as brought from the 

 colonies, forms the common insist or brown sugar of the shops. The 

 saccliarine particles are always mixed with other matter, which imparts 

 to the sugar a dark colour, a moist clammy feeling, and an empyreu- 

 matic odour. The object of the sugar-refiner is to remove these 

 impurities, so as to obtain the sugar in the hard white semi-transpareut 

 state known as loaf-sugar. 



The art of refining sugar, as well as that of extracting it from the 

 cane, is supposed to have been brought to Europe from the East, 

 probably from China ; but at what time is uncertain. The Venetians 

 are believed to have been the earliest sugar-refiners in Europe ; and it 

 is known that they practised the art before the discovery of America. 

 The Venetians originally operated upon the coarse black sugar brought 

 from Egypt, and followed the Chinese practice of converting it into 

 sugar-candy before they made loaf-sugar. Stow (' Survey of London ') 

 states that sugar-refining was commenced in England about 1544. 

 There were then two sugar-houses in London, but they yielded little 

 profit, because there were many sugar-bakers in Antwerp who in]. I 

 supply refined sugar to England better and cheaper than it could be 

 made at home. Subsequently, the commerce between England and 

 Antwerp being stopped, these two sugar-houses supplied all England 

 for twenty years, and became so profitable, that many other persons 

 embarked in the business. 



Few manufacturing operations have undergone more important 

 changes than that of sugar-refining. As generally practised until 

 within a recent period, the process commenced by mixing the raw sugar 

 in a large open copper with lime-water, and adding to the mixture when 

 warm a quantity of bullock's blood. The heat occasioned the serum of 

 the blood to coagulate, and in so doing to collect most of the impuri- 

 ties floating in the liquor, and to raise them with it to the surface of 

 the syrup in the form of a thick scum, which was carefully removed. 

 This clarifying process was sometimes repeated with a fresh quantity 

 of blood, or, as it is technically called, spice. When the liqno 

 thus rendered tolerably clear, and was partially evaporated by boiling, 

 it was further cleansed by passing it through a filter of thick woollen 

 cloth, which detained any particles of scum that might have been 

 left after skimming the liquor. It was afterwards concentrated by 

 boiling in a smaller open copper till sufficiently thick for graining ; 

 ifter which it was formed into loaves in the manner hereafter 

 described. For loaves of the finest quality a second refining followed 

 this. In the preceding section allusion has been made to the methods 

 of separating molasses from raw sugar by the vacuum-filter and the 

 lydraulic-press, both of which have been applied to the preparation of 

 sugar for refining; by the latter process sugar is now capable of 

 yielding loaves equal to double-refined by one process. 



