formula C.H120+2H2O. It occurs as a normal constituent in the juice of the heart, and of the involuntary or unstriped muscles, and has also been found in the tissues of the lungs, spleen, liver, kidneys, and brain, and in the urine in Bright's disease and diabetes. It has been recently shown that it is identical with the substance previously known as phaseo-mannite, which is readily obtained from the unripe seeds of the common kidney-bean (phaseolus vulgaris). It forms colorless efflorescent prisms, which lose two equivalents of water at about 212° F. (100° C.). When mixed with decaying cheese and chalk, it becomes gradually converted into lactic and butyric acids. Scyllite is a saccharine matter closely resembling inosite, and occurring in various organs of several plagiostomous fishes, and especially in the kidneys of the rays and skate. It differs, however, from inosite in its crystalline form, and in its containing no water of crystallization. Its composition is unknown. Sorbin, or sorbite, C6H12O6, derives its name from its occurring in the juice of the berries of sorbus aucuparia, the service tree, and may be obtained in colorless transparent rhombic octahedra. It reduces oxide of copper to the suboxide (Trommer's test), and is of a sweetish taste.

Closely allied to the sugars, but differing from them in their chemical composition (inasmuch as they do not contain hydrogen and oxygen in the proportions to form water), are mannite, C.H1406, obtained from manna, the inspissated juice of the fraxinus ornus, but also occurring in celery, onions, asparagus shoots, laminaria saccharata and other sea-weeds, certain fungi, the juice which exudes from apple and pear trees; dulcite, CHO, the product of an unknown Madagascar tree; quercite, C.H12O5, obtained from acorns; and pinite, C.H12Os, from pinus lambertiana, a tree growing in Australia and California. All these bodies are crystalline, and sweet to the taste.

Although chemists have hitherto looked upon the sugars as organic compounds, without any recognizable radical, and from their composition have termed them carbohydrates, "the researches of Berthelot render it probable that the sugars as well as mannite, and the bodies allied to it, are polyatomic alcohols, like glycerine, for he has found that they possess the power of entering into combination with various acids, with elimination of water, in some cases yielding colligated acids analogous to the tannic, and in others furnishing neutral bodies, closely allied to the fats." Miller's Organic Chemistry, 2d ed. p. 72.

Among the various chemical purposes to which the phenomenon of circular polarization may be applied, we may especially mention its use in determining the quantity of any kind of sugar in solution. While some sugars give a right-handed rotation, others give a left-handed rotation, and each sugar exerts a definite amount of rotatory power. The following are the rotatory powers of the chief varieties of sugar, equal weights of each being dissolved in an equal bulk of water, and the temperature being 59° F. (15° C.):

For details regarding the apparatus to be employed, and the method of using it, we may refer to Miller's Chemical Physics, 3d ed. p. 204; and to a memoir by Clerget in the Ann. de Chimie, iii., xxvi. 175. This method has been applied to determine the amount of sugar in diabetic urine, to ascertain the quantity of sugar which remains in the unfermented state in wines, and to other similar purposes. As, however, the process is one of extreme delicacy, this method must be used with great caution.

Manufacture. The manufacture of sugar from the sugar-cane and other sources is now one of the largest branches of human industry, but this great development is of comparatively recent date; and although there are evidences of its very high antiquity in India and China, sugar appears only to have been vaguely known to the Greeks and Romans. It is mentioned by Theophrastus as "honey in reeds;" and Lucan has the fol lowing line, which indicates a knowledge of its existence, but merely as a curious fact:

Quique bibunt tenera dulces ab arundine succos.

Its introduction to Europe appears to have been one of the results of the Crusades. The sugar-cane was grown in Cyprus about the middle of the 12th c.; it was from thence, at a later time, transplanted to Madeira, and at the commencement of the 16th c., was carried from the latter island to the West Indies. Originally, in all probability, only the sweet recent juice was known; for apparently the art of boiling it down, and forming it into raw sugar, was an invention of the 15th c.; and it was not until the middle of the following century that a Venetian discovered the art of refining sugar, which soon became established in Germany. The first refinery of which any notice exists was one in Dresden, as early as 1597; but long previous to this the subject had attracted so much attention as to be discussed in learned treatises, one of which in particular, the Sacchar ologia of Sala, in the beginning of the 16th c., shows that the clarification of the syrup by defection was then a matter of some importance. Still, the manufacture of sugar in the

countries to which it had been introduced made but slow progress, for its use was limited by its dearness to the wealthy. The material has now, however, become one of the commonest necessaries of life, and has largely conduced to the health of nations. Until 1747, sugar was supposed to be the product of the sugar-cane only, but in that year, Marggraf, a German chemist, demonstrated that it was a natural product of other vegetables, and especially of the beet-root; and half a century later, its manufacture from that source was first commenced in Silesia. A large portion of the sugar consumed on the continent is now obtained from this source. See BEET-ROOT SUGAR.

Since we have become better acquainted with the sources of sugar supplies, we have learned that a large portion of the raw sugar of the East Indies received in British ports as cane-sugar is in reality made from the juice of several palms, especially that of arenga saccharifera, and the wild date, phoenix sylvestris. The juice is obtained from these plants by cutting off the male spadix when young, and from the cut portion there is for four or five months a continual flow. The liquid is at first clear, and is immediately boiled down to a thick syrup, which granulates on cooling, and constitutes, if not otherwise purified, the coarse brown sugar called jaggery, which is extensively consumed in India. More carefully prepared, it is sent to Europe with sugar made in the caneplantations, and is only distinguished from it by well-skilled persons. If the juice is not immediately boiled, it becomes turbid, and passing into the vinous fermentation, forms the intoxicating drink called toddy.

In Canada and in the United States very much sugar is made by boiling the juice or sap of the sugar maple-tree (acer saccharinum). The sorghum saccharatum, or sugar-grass (see DURRA), and the stalks of ordinary maize or Indian corn (zea) yield sugar, which has lately been made so as fairly to rival the best crystallized cane-sugar (see under SUGAR-CANE).

Beet root sugar is manufactured from the fresh-dug roots, chiefly of the varieties we call mangold-wurzel. The process (which, however, is constantly undergoing modifications) is briefly described in the article BEET-ROOT SUGAR. Beet-root yields from 7 to 8 per cent of sugar, of which only 3 to 4 per cent are of the best quality, called melis, 2 to 3 per cent of the second quality, called farin, and the remainder molasses.

The manufacture of starch-sugar is described in the article GLUCOSE.

From the beginning of the 16th c., when the sugar-cane of India was introduced to the West Indies, sugar has been one of the most important products of those islands. Careful cultivation has produced many varieties of this useful plant, some of which are better adapted than others for particular localities. The original variety introduced into the West Indies is still cultivated under the name of the Creole cane; but the favorite variety is the Otaheite cane, which is the most luxuriant grower, and gives the largest yield of juice. It is the variety chiefly cultivated in Brazil, Demerara, and Venezuela, as well as the West Indies. In many parts of the east, another admirable variety is the Batavian or striped cane; it was originally raised in Java, and is the favorite with rumdistillers.

The extraction of juice from the sugar-cane is effected by simple pressure. In its native country, India, there are still in use in some districts machines of the rudest construction, which are probably the same which were used a thousand years since. The Chinapatam sugar-mill consists of a mortar made by cutting down some hard-wood tree to within 2 or 3 ft. of the ground, and hollowing the top of the portion left standing in the ground into the form of a mortar. A small hole is then bored obliquely through from the bottom of the cavity to the outside, and a pipe conveys the juice into a jar. A cylindrical piece of wood, sharpened at each end, acts as a pestle, and is kept in its place with sufficient pressure by a lever and ropes. Two men are required: one has a basket supplied with small lengths of freshly-cut cane, which he places, 2 or 3 at a time, in the mortar, and, when necessary, removes the crushed ones; the other man sits on the other end of the train, balancing it, and at the same time drives oxen which are attached to the end of the beam, and keeps the movable parts of the mill constantly turning round. Notwithstanding the rudeness of this contrivance, very large quantities of sugar are made by it in India. A much better one, however, is the Chica Ballapura engine, which consists of two upright rollers, the heads of which are formed into double spiral screws, which work in one another, so that when an ox is yoked to the long curved lever and goes round, one of the upright rollers, being connected with the lever, is made to revolve, and its screw carries the other one round, but in an opposite direction. The pieces of cane are fed in by hand between the rollers, and as the juice is squeezed out, it flows down into a small hollow below the frame made to receive it, whence a small trough carries it to an earthen pot. The frame of this mill is securely fixed with stakes driven deep into the ground. In all probability, this very ancient machine has been the origin of all the most modern ones, for they all consist of rollers placed either vertically or horizontally, between which the canes are made to pass.

The mills now in general use for squeezing the juice out of the sugar-canes are very powerful machines. Some idea of the strength of those mills will be formed from the fact, that one of the rollers weighs upward of 5 tons. The axles are 12 in. in diameter, and notwithstanding that they are made of the best wrought iron, they are not secure against breakage. The manufacture of sugar has probably been carried to greater perfection in the islands of Java, Mauritius, and Cuba, than in any other parts

Sugar.

of the world. In Java especially, in consequence of the great extent of the plantations, the planters have been able to erect very complete establishments for the manufacture of sugar.

The following very condensed account of the process of making sugar in Java will give some idea of the operation.

The canes, freed from all loose leaves, are passed through between the rollers under the greatest possible pressure that can be brought to bear upon them. The rollers revolve only from two to four times per minute. From 100 lbs. of canes, 65 to 75 lbs. of cane-juice will be expressed. This juice, which is of a sweetish taste, and of the color of dirty water, passes direct from the mill to a small reservoir, where it usually receives a small dose of quicklime, and without delay runs off to large iron or copper vessels, heated either by a fire underneath or by steam-pipes in the liquid. As the temperature of the juice rises, a thick scum comes to the top, which is either removed by skimming, or the warm juice is drawn off from below the scum. The concentration of the juice is partly effected in a series of large open hemispherical iron pans about six to eight ft. diameter, of which five or six are placed in a row, with a large fire under the one at the end. This one fire, which runs along under the whole row of pans, is found sufficient to make two or three of them nearest the fire boil violently, and in addition, it warms the juice in the pans furthest from the fire. As the juice firsts enters the pans furthest from the fire, it gets gradually heated, and the vegetable impurities rise in scum to the top, and are carefully removed. As the juice is ladled from one pan to the next, it boils with greater and greater vigor as it approaches nearer the fire, until in the pan immediately over the fire it seethes and foams with excessive violence; and this seems to be essential to the successful making of sugar. It is known that the presence of all those impurities which constitute the scum interferes with the crystallizing of the sugar; and the rapid ascent of bubbles of steam through the liquid in the pans carries all impurities dispersed through the body of the liquid to the top, where they can be removed with facility. It is well known that great heat is very destructive to cane-juice; that is to say, it turns much of the crystallizable sugar into treacle or uncrystallizable sugar, but the gain arising from getting rid of much of the impurity in the cane-juice more than compensates for the destruction of part of the sugar. After the concentration has been carried to a given point, and all the scum has been got rid of, the application of a high heat, which would act with an increasingly destructive effect as the condensation became greater, is suspended, and the liquor, now of the color of turbid port wine, and of the consistency of oil, is drawn into the vacuum-pan, where the concentration is completed at the lowest possible temperature, generally about 150° Fahr. The vacuum-pan is in universal use in all European sugar-refineries, and in all well-provided sugar-plantations. It is generally made of copper, of a spherical form, and from six to nine feet diameter. The bottom is double, leaving a space of an inch or two for the admission of steam between the two bottoms, and there is generally a long coiled copper pipe of three or four inches diameter above the inner bottom, so as to still further increase the amount of heating surface. This apparatus is made perfectly air and steam tight. Leading from its upper dome, there is a large pipe, communicating with a condenser into which a rush of cold water is continually passing, so as to condense all the steam or vapor that arises from the liquid boiling in the vacuum-pan. The water which is constantly rushing into the condenser is as steadily withdrawn again by pump. There is thus a constant vacuum in the pan, and, consequently, the liquid in it will boil at a much lower temperature than it would in an open pan or boiler. There is an extraordinary advantage in being able to effect the latter stages of concentration at a low temperature, for it is when the liquid becomes thick that the destructive results of a high temperature become most excessive. As the concentration of the liquid in the vacuum-pan proceeds, crystals of sugar begin to form, and the skill of the sugar-boiler is shown by the uniformity of the crystals he produces. The boiling is commenced by filling in only about a third or fourth of the quantity the vacuum-pan will hold, and gradually adding more liquid as the crystals increase in size. The sugar-boiler is able to watch the changes going on in the vacuum-pan by means of small samples he withdraws from it by means of a suitable apparatus. The sugarboiler holds those drops of thick fluid on his finger and thumb, between his eye and a strong light, and is thus able to detect those minute changes in its condition which show that it is time to add an additional quantity. By the time the vacuum pan is full, the contents have thickened, by the formation of crystals of sugar, into a mass of the consistency of thick gruel; it is then allowed to descend into a vessel called the heater, where it is simply kept warm until it can be run out into the forms," which, in the sugar-growing colonies, are generally conical earthen pots, holding from one to two cwts. of sugar. It is allowed to cool and complete its crystalization before the plugs, which close the bottom of the pots, are withdrawn. When this is done, from one-fourth to one-third of the contents of the forms, which has remained in a fluid state, runs off into gutters leading to large tanks, from which it is again pumped up into the vacuumpan, and reboiled, yielding a second quality of sugar. This reboiling of the drainings is repeated, with a continually decreasing result, both as to quantity and quality of the solid sugar obtained, and it is rarely carried beyond the fourth boiling. If the planter wishes to obtain Muscovada or unclaved sugar, the process is now complete, and the sugar is turned out of the forms, and packed for shipment. In some cases, the sugar is

66

Sugar.

run direct from the vacuum-pan into casks or hogsheads, which replace the forms, holes being bored in the bottoms of the casks, to admit of the uncrystallized portion of the sugar draining out.

If clayed sugar is to be made, the forms are allowed to stand for a few days until all the treacle has drained out; and a quantity of thin mud, about the consistency of good thick cream, is then poured over the sugar to the depth of one or two inches. The water contained in this thin mud slowly steals down through the sugar, and mixing with the coatings of treacle still adhering to the outsides of the crystals of sugar, renders them less viscid, and facilitates their descent to the bottom of the form. The mud remains, at the end of a few days, in the form of a dry hard cake on the top of the sugar, and none mixes with the sugar.

The process of claying sugar is simply washing off a coating of black or yellow treacle from a crystal of sugar, which is always white. This operation is possible without dissolving the crystal of sugar, simply because the treacle has a greater affinity for water than the crystallized sugar has. Anything that would yield a very slow and steady supply of water to the sugar, would do as well as mud or clay. There is always some loss of crystallized sugar in the process of claying, and attempts have been made to use strong alcohol for washing off the coatings of treacle from the crystals; but although alcohol dissolves treacle very freely, and scarcely acts on the crystals at all, still it has not been found to answer commercially. Besides the cost of the process, there is a difficulty in getting rid of the smell of alcohol in the sugar.

The centrifugal machine of Messrs. Manlove, Alliott & Co. has been very extensively used for getting rid of the treacle. Its action depends on precisely the same principle as that called into play when a sailor twirls a mop to expel the water from it. The centrifugal machine is simply a drum of 3 or 4 feet diameter, and 12 to 18 inches high, revolving at a great velocity on a vertical axis. The sugar, either direct from the vacuum-pan or after it has been allowed to cool, is put, still mixed with the treacle, into the machine. As soon as the drum acquires a high velocity its contents are forced by the centrifugal action against the drum, the cylindrical portion of which is made like a sieve, and admits of the escape of the treacle, but retains the crystals of sugar. Some idea of the efficiency of those machines may be formed when it is stated, that in a machine of 3 ft. diameter, revolving at the usual speed of 1000 revolutions per minute, the tendency of the treacle to escape will be 514 times its own weight; that is to say, the treacle will have 514 times more force to fly off than it has to drop off the crystal by the mere force of gravity.

Sugar-refining was unknown to the ancients, and even the refining previously referred to as having been established in Germany in the 16th c. consisted merely in clarifying the syrup, and producing a sort of sugar-candy; but one improvement followed another, until the process may now be considered as almost perfect. The chief difficulties attending the operation arise from the circumstance that the material to be operated upon is ever varying in quality. Not only is there a difference between the produce of two different plantations, but even the manufacture of the same plantation shows differences of quality; these differences arising chiefly from the presence of foreign substances, which seriously interfere with the operations of the refiner. The attempts made to test the exact quality of solutions of raw sugar by means of polarized light (see above) have hitherto been attended with little success in practice. Sugar-refining, as practiced in Britain, has three distinct objects (1) the production of loaves of thoroughly refined sugar; (2) crushed sugar; and (3) white sugar in separate crystals. The last is of comparatively recent introduction. In some existing sugar-refineries, old fashions still prevail; but our description must be confined to the most recent methods.

Sugar refining is carried on in the United States on a great scale, New York, Brook lyn, and New Orleans being the principal seats of the trade. There is comparatively little raw sugar used in Great Britain. Nearly all the yellow and dark-colored sugar sold in the shops has passed through the hands of the refiners, and is simply inferior sugar, made out of the syrup which drains from the white loaf-sugar.

Sugar-refineries are built eight or nine stories high, and the raw sugar is first hoisted to the upper story, where it is dissolved in large tanks of hot water, care being taken to use as little water as possible for the purpose. A quantity of bullock's blood is stirred into the solution of sugar, and the heat being gradually raised, the albumen of the blood coagulates, and rises to the surface in the form of a thick light scum, bringing with it nearly all the mechanical impurities floating in the fluid. The liquor, still hot, is then passed into bag filters. Those filters are made of a very closely woven cotton cloth, capable of retaining the minutest mechanical impurity. In order to facilitate the passage of the liquor through the bags, they are suspended in a kind of iron closet, and surrounded by an atmosphere of steam to keep the liquor hot. From the bag-filters the liquor, now freed from all mechanical impurities, but of a dark color, flows into a lofty cylindrical iron filter, of about 5 or 6 ft. diameter, and 20 or 30 ft. high, filled with animal charcoal, that is, charcoal made of bones. This charcoal is reduced to coarse powder; and the dark offensive liquor is allowed to percolate very slowly through the mass. The result is, that it flows out at the bottom a perfectly transparent and pure solution of sugar. The charcoal can only be used for a few days at a time, because it gradually loses its purifying power; when the liquor begins to flow through it without

being purified, it is taken out of the filter, and reburned, which completely revives its powers.

The liquor as it flows from the charcoal filter is a mixture of pure sugar and pure water, and perfectly transparent. The application of heat is the only mode of expelling the water, and this unfortunately blackens the sugar again. In order to get rid of the water with as little heat as possible, the colorless liquor is boiled in the vacuum-pan as in the early process of the manufacture. The liquor boils in vacuo at about 150° F., and even this moderate heat has the effect of turning it quite brown. When it has been sufficiently concentrated by boiling in the vacuum-pan, which takes from 1 to 2 hours, it is run into the sugar-loaf forms; which, after cooling, are carried to a room kept warm by means of steam-pipes. This warmth facilitates the flow of the treacle or syrup out at the aperture at the bottom of the form. To get rid of the coating of colored treacle which still hangs about the crystals of sugar, a small quantity of a saturated solution of pure white sugar is poured on the top of the form. This strong liquor is unable to dissolve any more sugar, but being more fluid than the sticky coatings of treacle or syrup adhering to the crystals, it mixes with the coatings, and makes them fluid enough to flow down to the bottom of the form, leaving the crystals clear of syrup or treacle, and consequently free of all color. This process of washing off the coloring matter from the crystals of sugar is the same in principle as the "claying" used in the production of sugar. The loaves of sugar, after standing some time, to admit of all the liquor draining off, are wrapped in paper, and dried in stoves heated by steam. The liquor draining from the forms is reboiled in the vacuum-pan, and forms loaves of an inferior quality; and the liquor draining from the inferior loaves is again boiled into the yellow sugars known among sugar-refiners as bastards.

Crushed or crashed sugar is simply inferior loaves crushed while still soft and moist, and packed in hogsheads, instead of being left in the loaf form.

The syrup which drains from refined sugar is reboiled, and constitutes the golden syrup of the shops.

Crystal Sugar.-In making the sugar crystals, all the processes are carried on as in refining, until the syrup is clarified. Then it is boiled or concentrated in a vacuum-pan of larger size than ordinary, and the concentration is carried on until minute crystals appear. Fresh syrup is then added from time to time, great care and experience being required to insure a regular feeding of the first-formed crystals, and prevent the formation of a second crop. When the crystals are large enough, the contents of the pan are transferred to the centrifugal machines, which quickly separate the crystals in a perfectly dry state from the uncrystallizable syrup. The crystals are of a square tabular form, with a deep groove across in one direction, dividing the crystal into equal parts. This kind of sugar is much liked for coffee, etc., but the crystals dissolve with difficulty.

The loss of such a large portion of the sugar in the processes of manufacturing has led to many inventions for the extraction of the juice, and for its more economical conversion into sugar. The cane mills now generally used are provided with three rolls, and with them the yield is not more than 70 to 80 per cent of juice, the lower limit being the more common. Seeing that with the most powerful rolls much juice is still left, other machines have been employed. Among these are the defibrators. In one of these the cane is reduced to a pulp; it then passes into a press, which squeezes out the juice. In another process the cane is put through a machine that breaks all the joints and outer covering; in this condition it is passed through an ordinary mill. The previous cracking of the joints allows a more constant and uniform pressure in the mill. Both of these methods give a better yield than the ordinary single milling. Duchassaing has invented a machine in which the cane first passes through one set of rollers; it is then carried along on an endless cloth to a second mill; between the first and second are a number of jets, which discharge boiling water upon the cane; thoroughly wetted, it goes through the second mill. With this machine the yield of sugar has been increased from 9.4 per cent to 11.04 per cent. The principle of osmotic action has been applied to extraction of the sugar. In the cane the sugar is held in solution in cells, inclosed by vegetable membrane. This membrane acts as the septum, and when the sliced cane is placed in water, the sugary solution in the cell passes out, until the density of the two liquids becomes the same. The water containing the sugar is then drawn off, and a new supply added, when the sugar again passes out; this process is kept up till all the sugar is extracted. If for every gallon of juice we use a gallon of water in the first step, one half the sugar would be extracted. To carry on the process economically, the first water should be applied to the second cane, and so on, till at last it should be as rich in sugar as the cane juice. The juice obtained in this way is free from all the crushed and broken cane. The cane is sliced diagonally into thin chips, so as to expose as large a surface as possible to the water. The inner part of the cane contains a richer juice than the outer, and less mineral matter than the knotty portions; the juice also varies in the different varieties and with different soils. According to Dr. Icery, of Mauritius, it contains water, 81, sugar, 18.36, mineral salts. 29, and organic substances, .35. The presence of a certain amount of uncrystallizable sugar is a source of great loss, as it not only does not crystallize itself, but prevents an equal amount of the sucrose from crystallizing. Fermentation converts sucrose into invert sugar. This takes place in the cane under the influence of air and a moderately high temperature. After the juice has been expressed the acid in it sets up fermentation. In