Referring to Chemistry (vi., 515-17) for the composition and chemical relations of sugar, we propose in the present article to give a brief technological view of the subject. Sugar, in one or other of its varieties, is widely diffused, and imparts sweetness to the juices of many vegetables. The practice of sweetening food is older than the knowledge of sugar. The ancients used honey for the purpose; and when the sweet produce of the cane became known it was called mel arundinaceum. In the first century, Dioscorides refers to the canes of India and of Arabia Felix as producing honey, and applies to it the term exaxypov, or sugar, which Pliny refers to as being used only in medicine. Sugar was not known in northern Europe, at least as an article of food, until the time of the crusades. The sugar-cane was introduced into Cyprus from Asia, and was noticed in A.D. 1148 as being extensively cultivated in that island. It was transplanted from Cyprus to Madeira, and thence, in 1506, to the West Indies. The sugar-cane is said to have been also cultivated on the coasts of Andalusia before the invasion of the Arabs, who seem to have introduced the method of boiling down the juice for the production of sugar. The refining of raw sugar is of later date, and is referred to Venice. The refining of sugar was commenced in England about 1544; but loaves of sugar are spoken of as being sold in Scotland so early as 1829. There was a refinery in Dresden in 1597. Sugar-candy is noticed in the Alchemia of Libanius in 1595, and this is probably the form in which sugar was known to the ancients. The general introduction of tea and coffee caused a great demand for sugar, before which, and so late as the end of the seventeenth century, syrup and honey were in use among the poorer classes of Germany. In 1747, Margraf discovered cane-sugar in the roots of many plants, especially in beet-root; but no attempt was made to manufacture that variety of sugar on an extensive scale until the time of Napoleon, who, in attempting to ruin the colonial trade of Great Britain, excluded our merchant-ships from the conti- Sugar.
ment, and, to supply the demand for sugar, offered premiums for its manufacture from beet-root. Much skill and ingenuity were exercised in the manufacture, which is still extensively carried on in countries where the richer juice of the cane is excluded from competition by heavy imposts.
The sugar-cane (Saccharum officinarum) is a perennial plant, belonging to the family of the grasses. It varies in height from 6 to 15 feet, and upwards, and in diameter from 1½ to 2 inches. Its stalk is knotty, with a leaf and an inner joint at each knot. The roots are slender, and nearly cylindrical, about a foot in length, furnished with a few short fibres. The joints of the stalk or cane may vary in number from 40 to 60, and in the Brazilian cane they are as many as 80. The Otaheite cane has fewer joints, and they are further apart. Every joint contains a bud, which encloses the germ of a new cane. "The joints of the cane," as Mr Porter remarks in his work on the sugar-cane, (1843), "may be considered as concentric circles, the centre of which is always occupied by a point, which, expanding into a circle itself, is replaced by a new point, circles which, rising successively one upon the other, enlarge and arrive in a given time at their greatest diameter." The first joint requires 4 or 5 months for its complete growth, during which 15 or 20 joints spring from it in succession, the decay of the leaf indicating the maturity of each joint; and when the leaves of the first two or three joints have withered, there are 12 or 15 leaves at the top, arranged like a fan. The last joint is called the arrow; it is 4 or 5 feet in length, and is terminated by a panicle of sterile flowers. The period of flowering is usually delayed by cultivation, new joints being formed instead. The sugar-cane requires a moist, nutritive soil, and a tropical or sub-tropical climate. It is propagated by slips or pieces of the stem with buds on them, and it requires from 12 to 16 months to arrive at maturity. The leaves fall off before flowering, and the stem becomes of a straw-yellow colour. The plantation should be managed so that the canes may ripen in succession. The land, unless naturally rich, requires abundance of manure, but saline matter should be avoided, since common salt, chloride of potassium, and muriate of ammonia, form non-crystallisable compounds with the sugar. One equivalent of common salt, for example, = 60, will combine with two equivalents of sugar = 342, and thus cause a loss of sugar 6¼ times greater than the weight of the salt in the compound. Beet-root sugar factories situate near the sea-shore have experienced great losses from this cause, which also operates to some extent on the windward coast of Barbadoes. After the cane harvest, the roots strike again and produce a fresh crop, but in about six years they must be removed; this period, however, is subject to variation in different places. The canes should be cut in dry weather: they should have a smooth, brittle skin, considerable weight, greyish pith, and a sweet, glutinous juice. The developed buds which form the secondary stole of the plant that has been cut are named rattoons, and they are first, second, or third, &c., according to the age of the parent root. They diminish every year in thickness and length of joint, and are said to yield a richer juice and to produce finer sugar than the original plant. The canes should be cut close to the stole, for this gives vigour to the rattoons, and, moreover, the lowest joint contains the richest juice. The cane-top, with one or two joints of the cane, must be cut off and rejected, as the juice of those parts is watery. The canes are tied up in bundles and sent to the crushing-mill, the amount of work done by this regulating the quantity of canes to be cut; for if the cut canes are kept many hours, they will ferment and spoil. The cane-mill usually consists of three massive cast-iron rollers, about 24 inches in external diameter, with projecting rims to prevent the canes from spreading over the sides, arranged horizontally, two below and one above and between: they are worked by means of toothed wheels attached to the axles. The canes are passed down an inclined plane between the first lower and the top roller, and, being crushed between them, are guided by plates between the top roller and the second lower roller, where the crushing is completed. The juice passes into a channel below, and thence to a reservoir. The first pair of rollers crushes the cane, and the second pair expresses the juice, and turns the crushed cane down a trough out of the mill. The first lower roller is usually grooved. In order to obtain the largest proportion of juice, the rollers must be set very close together, and revolve slowly under steam-power. It is stated that when the power was wind, only from 50 to 56 per cent. of the juice was obtained; animal-power gave 58½; water-power, 61½; and steam, 70 per cent. In general, however, the average of steam is not superior to that of water. From 12 to 14 tons of good ripe cane produce about 1500 gallons of juice, which are required for making one hogshead of sugar. The crushed cane known as cane-straw, bagasse, or cane-trash, is used as fuel in evaporating the juice; it contains at least 18 per cent. of cane-juice. The opinion has been repeatedly expressed that the cane-trash should be returned to the land as manure, and, if spread over the spaces between the cane-roots, it would also serve to mitigate the effects of severe drought. Coals can be sent to the colonies from Great Britain at a cheap rate to supply the demand for fuel.
The juice of the cane is a solution of sugar in water, with traces of albumen, of gum, and of a peculiar substance resembling gluten, or vegetable gelatine; also a minute proportion of cerosin, and of a green vegetable wax. The mineral ingredients resemble those of other plants and vegetable juices, and consist of the sulphates of lime and of potash, chlorides of potassium and of sodium, phosphate of lime, silica, &c. The juice has usually a yellowish colour, but is sometimes colourless, and greyish globules suspended in it render it turbid. It has an agreeable but rather insipid taste, and a peculiar balsamic odour. It contains from 17 to 20 per cent. of crystalline cane-sugar; but the planter does not obtain more than 7½ per cent. There is a loss of sugar in the mode employed of expressing the juice from the cane; and, secondly, a loss arising from the chemical change due to exposure to the air, whereby the crystalline sugar becomes degraded into mucilaginous or non-crystaline sugar, commonly called molasses. Indeed, did space permit, it would be easy to show that the loss to the planter commences in an imperfect system of agriculture, the ground being worked by hand-hoeing instead of deep ploughing, and from a frequent absence of agricultural and manufacturing machinery of improved construction.
The exposure of the juice to the air of a tropical climate, even for half an hour, would cause fermentation to set in; lime is therefore immediately added for the purpose of neutralizing the acid, and rendering some of the soluble impurities insoluble. The old method of clarification, or defection of the juice, is by heating it in iron pans or teaches, arranged together in a row, and heated by one common fire. The juice-reservoir below the crushing-mill supplies the largest pan, the fifth in the row, and farthest from the fire, with juice. The milk of lime, or temper, as it is called, is equal to about ¾th of the weight of the juice, but the proportion varies with the quality of the juice, and the effect of the heat, which should not exceed 140°, is to
There are three species of cane recognised by the cultivator:—1. The Creole cane, with dark green leaves and a thin knotty stem; it is indigenous in India. 2. The Bastard or Striped cane; it has a dense foliage, and is covered with purple stripes. 3. The Otaheite cane, which is the most luxuriant and juicy, and is cultivated in the West Indies and South America. coagulate the albuminous portions of the juice, which rise to the surface in the form of scum. This is removed by skimming; and the juice is passed through the other four teaches, and evaporated at increasing temperatures until the sugar will crystallize out on cooling. Scum collects on the surface of each teaché, and a great deal of it is nearly pure sugar decomposed by the heat; it is passed into the molasses cistern, and is used for making rum. The teaches diminish in size as the juice diminishes in volume, and it is ladled by hand from one teaché to another, thereby leading to further deterioration by exposure to the atmosphere. The syrup is passed from the last, or skipping teaché, to the coolers usually by means of shoots, and it is known when the granulating point has been attained by taking a portion of the syrup upon the thumb, and placing the forefinger upon it, separating them so as to draw out a thread, and if it extend to the length of about an half-inch, the sugar is judged to be sufficiently boiled. This trial by the touch is thought to have given the name of teaché or tayche to the pans, the term being sometimes restricted to the last or hottest pan. The coolers are shallow, open vessels of wood, in which, in the course of twenty-four hours, the sugar grains, or forms into a soft mass of crystals, embedded in molasses. The temperature in the coolers is rendered equable by stirring up the mass from time to time with iron rods. The contents of the coolers are removed to hogsheads, or potting-casks, placed on an open framework in the curing-house. The bottom of each cask is bored with holes, an inch in diameter, each hole containing a plantain stalk, or a crushed cane, long enough to reach to the top of the cask. The soft sugar is placed in these casks, and the molasses gradually drain away through the spongy stalks into a cistern lined with lead, forming the molasses reservoir. It may take from two to six weeks before the sugar is sufficiently dry for shipment; and there is a further drainage of molasses in the hold of the vessel, promoted by the deliquescent salts absorbing the damp air, and entailing a further loss of sugar, said to amount on an average to 12 per cent.
Such is the old system of manufacturing sugar, which, we regret, is not yet altogether abandoned in our colonies. Under this system it has been calculated that from every 1000 parts sugar-cane, from 60 to 80 parts raw sugar, and from 25 to 30 of molasses, are obtained; while, according to chemical analysis, the yield should be from 180 to 200 parts of crystallized sugar. Mr Kerr states, that of the 1500 gallons of juice required for a hogshead of sugar, netting 15 cwt. in the English market, the planter does not get a return of more than 6 per cent. of moist Muscovado sugar, and that of very inferior quality.
In proceeding to notice the more important of the improvements which have been suggested, and in many cases adopted, for improving the manufacture of raw sugar, we may state that the objects had in view have been the protection of the juice from fermentation, and its concentration with as little agitation and exposure to the air, and at as low a temperature as possible. Dr Mitchell proposed to dip the canes into hot water as soon as they are cut, for the purpose of coagulating the albumen, and preventing it from passing into the juice, and also to destroy the vitality of the glutinous fermenting matter. M Payen recommends sulphurous acid or bi-sulphite of lime to be used instead of milk of lime. The French have also invented a contrivance for raising the juice from the crushing-mills to the clarifying vessels with but little agitation, by means of an apparatus called a monte-jus; in which steam acting on the surface of the liquor forces it up a pipe into the clarifier. This vessel, too, instead of being a naked copper, exposed to the fire, is surrounded by a cast-iron jacket, and steam being admitted into the space thus formed, a moderate and regulated temperature can be commanded. The bottom of the pan is furnished with a plug, containing two or three holes, one for disposing of the clear liquor, and another, and larger one, for passing off the thick scum and sediment. The juice is clarified at a temperature of 176°; particles which rise to the surface are skimmed off, and milk of lime is added in quantities just sufficient to neutralize the acid, and this is regulated by the frequent use of litmus-paper. When the scum on the surface begins to crack, the steam is shut off, and the whole is left for fifteen or twenty minutes, during which time the lighter impurities will have risen to the surface, and the heavier ones will have subsided. A hole in the plug, 3 or 4 inches above the bottom, is thrown open, and the liquor, which should be pale and clear, allowed to flow out; the heavy matters and the scum are passed through the larger opening into a cistern, and then placed in bags, and the juice expressed. The clarified juice still contains matters in suspension, which are removed by passing through fine copper-wire sieves, or flannel-bag filters, from which the filtered liquor is passed through a bed of bone-black, by means of which vegetable colouring matter is more or less removed, together with any excess of lime, and also mineral salts, originally present in the juice. The filtered liquor is next concentrated in open pans, heated by means of steam-pipes to about 25° to 28° Beaumé. The further concentration of the juice is completed in the vacuum-pan, as in the refining of sugar. There is also another contrivance for preparing the juice for the vacuum-pan. A series of straight copper pipes, placed one above the other, with the ends fixed in cast-iron boxes, or united by curved end pieces, is placed so as to receive the waste steam of the vacuum-pan, and over this arrangement of pipes thus heated, the weak juice is made to fall in a multitude of drops; so that while condensing the steam within, the juice sends off a considerable portion of vapour, and falls in a more concentrated state into a vessel below, from which it can be pumped up into the vacuum-pan.
As the vacuum-pan is no longer restricted to the refining of sugar, it may be noticed in this place in connection with the manufacture of the raw product. It depends for its action on the principle that liquids boil at temperatures dependent on the pressures they have to sustain. Thus water, under a pressure of 30 inches barometer, boils, that is, becomes rapidly converted into steam at 212° F., whereas water in vacuo will boil at about 80°. The vacuum-pan was patented by Howard in 1812; it consists, in its improved modern form, of a copper pan with a cast-iron jacket, within which steam is admitted for heating the pan, while within the pan, and corresponding to its curvature, is a worm or coil of copper pipe, through which steam is passed for boiling the juice. The pan is covered by a copper dome, fitting to it air-tight. In order to preserve a vacuum, or at any rate a greatly reduced pressure within the pan, the steam, as fast as it is generated by the boiling of the juice, is pumped out into a condenser, and condensed by the injection of cold water, or by the trickling of weak juice over a system of condensing pipes, as above described. In order to withdraw and examine the juice during the boiling, without disturbing the vacuum, a cylinder passes from one side of the domed top down into the liquor, which cylinder contains a piston called a proof-stick, furnished with a notch or receptacle, which becomes filled with sugar on plunging it down the cylinder, and can be withdrawn to a sufficient extent to bring the sample to the outside. A thermometer passes through an air-tight collar for indicating the temperature, and there is a barometer or vacuum-gauge for showing the internal pressure. There is also a measuring vessel of about 35 gallons, for regulating the quantity of juice admitted into the pan. There is also an overflow vessel for catching any liquor that may boil over from the pan. There are also peep-glasses in the domed top, one opposite to the other, so that, on looking through one, sufficient light passes through the other to show how the boiling is going on within. The bottom of the pan is a gun-metal saucer, ground into a socket, and on lowering this by means of a lever, the sugar can be run out of the pan. In connection with the vacuum-pan is also an expansion vessel for reducing the pressure of the steam to the point required within the pan. The heat employed for evaporating the weak syrup is from 180° to 190°; when the syrup begins to granulate the temperature is lowered to 160°, and just before the evaporation is completed, the temperature is lowered to 145°, the lowest temperature at which proof-sugar will boil under a pressure of 3 inches below a perfect vacuum. When the attendant finds by drawing out a thread against the light that crystals are beginning to form, he lets in another measure full of syrup into the pan, and continues the operation until the whole charge has been admitted.
The crystals first formed seem to act as nuclei to the next charge. A large pan, 8 feet in diameter, for example, will boil 80 tons of sugar in 24 hours; but in smaller pans the skip or panful of concentrated sugar may be made in from 1½ to 2½ hours from the commencement of the boiling. Fine grained sugar requires a larger measure of syrup at each charge than the coarse. The concentrated juice, or proof-sugar, as it is called, consists of innumerable small crystals floating in syrup, and it is passed out of the pan at 145°, not into a cooler, as in the old process with the teache, but into a heater or copper pan, with an iron steam-jacket, raised to 180°, the temperature best adapted to the forming and hardening of the crystals. During this time the sugar is stirred with wooden oars to prevent granulation; it is ladled or run out into buckets or scoops, and so poured into moulds or small inverted cones, which are perforated at the point, but at first the hole is stopped with paper, and so they are left until the following morning at a temperature of about 100°, when the holes are opened and the temperature maintained for 3 or 4 days, during which time the process of liquoring is performed, that is, a saturated solution of pure sugar is poured into the top or wide part of the moulds, and this filtering through the mass carries with it the rest, or much of the colouring matter. The moulds rest with their points in pots or jars, which receive the drainings. When properly drained the sugar is turned out of the moulds in the form of loaves, which being trimmed to shapes, are dried in a hot room, and are then ready for the market. In this way, sugar, equal to refined, can be produced from the canes at one operation; indeed the work of the refiner in England is chiefly to remove the defects occasioned by the imperfection of the planter's apparatus: in fact, raw sugar, as generally supplied to the public, is a very impure product in consequence of defects in the manufacture which tend to lessen its sweetness, impart a coarse flavour, injure its colour, and render its solution milky or muddy. But in addition to chemical impurities, there are mechanical ones, such as earths, vegetable matters, and insects, the last of which may produce a well-known disease in the hands of the grocer.
The improved methods of manufacture which we have pointed out have been to a certain extent adopted, or are being gradually introduced. In Java, Cuba, and other places, where improved machinery has been introduced, an increase of from 30 to 40 per cent. on the quantity of sugar produced has been effected, while the market value has risen from 5s. to 10s. per cwt.
The various qualities of raw sugar imported into this country will be noticed presently; but it will be convenient first to review briefly the operations of the refiner. The cases, bags, and hogsheads of sugar are made to discharge their contents on the floor, and the casks are inverted over a steam-jet pipe, which quickly removes all the sugar that adheres to the staves. The sugar is passed through a sieve to break up the lumps, and water is added, and the solution quickly effected by the assistance of steam, which is made to blow up through a perforated pipe placed at the bottom of the pan; whence the melting pans are sometimes called blow-up cisterns. Even at this early stage it was recommended by the late Mr Finzel to substitute a vacuum-pan for the blow-up cistern, by which means the solution is said to be effected with greater rapidity, while exposure to air and high temperature are avoided. It has been found, however, in practice, that the impure sugars have so strong a tendency to froth up, that the vacuum-pan is constantly boiling over, so that the plan has been abandoned. While the sugar is being dissolved in the blow-up cistern, a small quantity of blood and some lime-water are added, to clarify the solution and neutralize the acid. The solution is kept in motion by a mechanical stirrer, or by two or three men with ears. The quantity of blood is not more than about ½ per cent., and its action is assisted by from 3 to 6 per cent. of powdered animal charcoal. The temperature is kept for a short time below 165°, at which the albumen of the blood coagulates, after which steam is fully admitted and the solution made to boil. The albumen being dispersed through the solution and then coagulating, forms a net which entangles the mechanical impurities, and rises with the charcoal in the form of a thick compact scum, which is removed. The liquor has been partly decolourised by the action of the charcoal, but it still contains impurities in suspension coated with albumen. The liquor is therefore passed through bag filters or long bags, from which it passes through charcoal beds, which, in the course of 15 or 20 hours, decolourise a quantity of syrup containing four times as much sugar as there is charcoal in the filters. The liquor is now passed into the vacuum-pan, and is concentrated to the density of 42° or 43° B, at a temperature varying from 230° to 240°. In this condition the sugar is held in solution by the high temperature, and when allowed to cool, rapid crystallization takes place, producing that fine sparkling grain which characterizes leaf-sugar. It is necessary, however, to transfer the liquor to the moulds at a certain temperature, just as the crystals have begun to form, and this is regulated in the vessel below the vacuum-pan into which the liquor is received, and from which a number of men fill their scoops and charge the moulds. The saccharine mass falls into the moulds with a sound as of wet sand, showing the formation of crystals in the mass. The moulds are of iron, coated with varnish or glaze, or painted. Galvanized iron moulds have been introduced, but they do not give to the surface of the loaf so good a texture as the ordinary iron moulds. The holes in the points of the moulds are stopped up during the filling, which is performed on the lowest floor, and they are raised by an endless chain or band, called a mould-carrier, to a floor above. The sugar is frequently stirred to prevent it from crystallizing at the sides, and to promote the formation of a compact net-work of small crystals enclosing the mother liquor or saturated solution, which is impure and coloured, while the crystals are pure and colourless. The liquid portion is somewhat viscid, and drains off with difficulty, although assisted by a temperature of 75° and upwards. When the plugs are removed, the draining is allowed to go on for 24 hours. The first syrup that drains off into pots or troughs placed to receive it is called green syrup; the after syrups are called seconds and drips, and are more valuable, because stronger and of better colour. The syrups are passed through tunnels and pipes into their proper cistern, the different syrups being kept apart for re-boiling. After the sugar has set, the face is cut out with a trowel, and the scrapings, with other similar sugar material, is formed with water into a magma or pasty mass, which is poured into the several moulds for the purpose of removing the colouring matter. After this, nearly saturated solutions of refined or other white or fine sugars are applied cold to the surfaces in small quantities by means of a ladle. Sugar.
or a nose-pipe, the last in succession being the finest. By this means the coloured syrup is completely removed by the passing through of the pale or colourless syrups, and a coating of pure sugar is given to the grains, so that after having passed through the stove the sugar has lost its hygrometric quality, and remains permanent in the air.
The process of claying, as it is called, has the same object as the above, and may be used instead of, or in conjunction with it. White pottery clay, washed, to separate soluble matters, is made into a thin paste, and placed on the sugar in the mould, in a cavity formed by loosening and scooping out the sugar. It is also usual first to remove the sugar from the mould, and take away the solid crust formed at the point. The action of claying is as follows:—
The water which separates drives the molasses before it, and becoming itself a saturated solution of sugar, sinks through the loaf, expels the mother liquor, and thus gets rid of the colouring matter. The syrup which drains off is termed clayed syrup. When the sugar is removed from the moulds, the point is usually knocked off, and a new top afterwards produced, by turning between crooked knives, and then the loaves are dried in a hot room at 75°, which is gradually raised to 122°.
The above methods of cleaning the sugar are tedious, and various modes of quickening the process have been tried; such as the action of compressed air on the surface of the mass; the production of a partial vacuum below the moulds (known as the pneumatic process); and thirdly, the centrifugal process; this has been tried in two ways.
1. The moulds, with their contents, were set in a circular machine, and whirled round with great velocity. This dangerous plan, however, has not come into use, at least not in Great Britain.
2. The sugar is run in a pasty state into the wire-basket, or perforated plate vessel of a hydro-extractor, which, revolving at the rate of several hundred turns per minute, during a period of from 3 to 15 minutes, according to the quality of the charge, a dry granular sugar is thus produced fit for the market. When the plan was first introduced by Mr Finzel, the product consisted of large beautiful crystals of pure sugar, which were for a time in favour; but the very perfection of the crystalline structure, rendering this sugar less soluble in the same time than an equal weight of a coarser raw sugar, it was declared not to sweeten so well, and it did not maintain the position it deserved. The plan, however, has since been modified: the apparatus has been simplified, and the granular syrups being put into the perforated cylinder, the latter is made to revolve from 1200 to 1500 times a minute during a space of five minutes, the result is a clean, granular, sparkling, light-coloured moist sugar, for which there is now a great demand in London. The syrups whirled out of the extractor during the process are boiled down with other syrups, and again passed through the machine. The centrifugal machine has been introduced into the colonies with advantage to the planter, and the marked improvement of his product. We may also mention, that the superior variety of treacle known as golden syrup is obtained by passing the treacle once through a charcoal filter.
Refined sugar, of the first quality, is prepared in small moulds, and the various syrups which drain off from it during the cleansing produce several kinds of what are called bastard sugars. Some of these syrups produce sugar too soft for loaf, but furnish a superior quality of moist sugar. Others are run into large bastard moulds, and are crystallized at a higher temperature in proportion as they are impure. A small first quality mould will contain about 30 lb. weight of wet granulated sugar, from which about 10 lb. of green syrup will drain off, and if the remaining 20 lb. be dried without claying, the weight will be 17 lb., but if clayed only 11 lb.; but the sugar is of the first quality. A bastard mould will contain 60 lb. of granulated sugar of the second quality, from which 25 lb. of molasses will drain off, leaving 35 lb. of unclayed moist sugar, or 32 lb. when dry; but if this be clayed and dried it will produce 17 lb. of second quality loaf-sugar. The time occupied in refining varies from 8 to 10 days, but for the inferior qualities longer. What is called stamped sugar is prepared from the inferior qualities, by grating the moist soft lump, passing the flour through a sieve, and, while moist, stamping it in layers in a first quality mould, from which it is removed and dried.
The large crystals of sugar known as sugar-candy are prepared chiefly in Holland and Belgium, from syrup boiled over an open fire, and set aside to crystallize in a vessel in which strings are stretched, to serve as nuclei to the crystals. In the course of six or eight days the crystallization is complete, and the vessel, which is contracted towards the bottom, is inverted, when, after breaking up the surface, the syrup drains off, and the crystals are removed and dried. The usual crystalline form is a six-sided prism, commonly flattened, and terminated irregularly. A solution of sugar, saturated at 230°, forms, in cooling, a granular mass, or tablet; but when rapidly boiled until it acquires a tendency to a vitreous fracture on cooling, or when sugar is fused at about 280°, or from that to 320°, so that a portion feathers or concretes on being thrown upon a cold surface, it may be poured out upon a marble slab, and will cool into an amorphous mass. Such is barley-sugar, so called from the sugar having been formerly concentrated by rapidly boiling in barley-water or sweet wort. It is usually sold in sticks, to which a spiral twist has been given while hot. This vitreous transparent substance deteriorates by keeping. It becomes opaque first on the surface, and then throughout the mass, passing in fact into the crystalline condition; heat is given out during the change. Confectioners add a little vinegar or tartaric acid to the sugar, which retards, if it does not altogether prevent, the opacity. The show-sticks resembling barley-sugar in grocers' windows are made of coloured glass.
The sugar-refiner receives most of the sugars of commerce into his establishment, and it will be well to enumerate the principal varieties of them here. West Indian and other American raw sugars are known as Muscovado, from the Spanish, or rather Portuguese word mascabado, "more advanced." These are made marketable by being crystallized and cleared of molasses, without any attempt to dry or decolourise them. They form the favourite scale or grocery sugars of this country, the muscovado of Jamaica being preferred. There is, however, an important exception in the case of Cuba, three-fourths of the sugar from that island being clayed. Clayed sugar is not so large or well defined in its crystals as muscovado. The removal of the coating of syrup from the surface of its crystals gives it a grey and less pleasing shade or complexion than muscovado, which, when well made, is bright yellow or straw-coloured. The clayed sugars, therefore, are not used for grocery sale. What is called white clayed is that portion which forms the upper part of the mould in the process of claying; it is whiter or further removed from brown than ordinary clayed. Clayed sugars are commonly stronger, that is, they yield a larger percentage of refined sugar and less of the lower products than muscovado. The sugars of St Croix are much admired. The sugars of Porto-Rico and Barbadoes are esteemed; but the softness and quantity of foot, as the wet side of the contents of the cask is called, in the case of Barbadoes sugar, is an objection. The sugars of Brazil are usually clayed, and are sold as white clayed and brown clayed, the latter being nearer the apex of the mould. The Mauritius produces two-thirds as much sugar as all our West Indian colonies together. The sugar is subjected to a process analogous to claying; that is, it is washed with a surface application of concentrated cane- juice, which percolates through the mass as the water does in claying. Such sugar is spoken of as clairé; it is much esteemed by the refiners of France and of the United Kingdom. There is an inferior class of sugars (analogous to refinery bastards), known as syrup sugars, prepared from the molasses of the foregoing varieties, and from that obtained from lower kinds. The sugars of the British East Indies are made by various processes, and are of various qualities, as indicated by the names Khaur, Goor, Jogery, the two former belonging to Bengal, the last to Madras. Some sugars made by European refiners in Hindostan are named after the factories where they are worked, such as Cossipore, Ballykhal, &c. The sugars of Java are mostly clayed. They are well adapted for refining, and are chiefly used in Holland. The Philippine Islands produce Manila sugar; it is a strong brown raw material, adapted for refining. Much of it is unclayed, and under the names of Taal, Zebu, &c., finds its way to the Australian and British markets. It is converted into yellow crushed sugar.
In addition to these tropical sugars there are occasional importations of brown sugar in cakes or loaves (Rapaduros). Such sugars are made in small establishments, and are moulded often without parting with the molasses. Attempts have also been made to introduce cane-juice in a concentrated or inspissated state for the use of the refiners, but without much success. The Melado of Cuba is of this kind. The sugars imported into the British markets are distinguished as British colonial, foreign, and beet, the first being the produce of our own colonies, the last of the continent of Europe. Maple sugar is never imported except for presents. Date sugar is largely used by the refiners. Beet raw sugar is imported from France by the refiner, but requires to be used with caution on account of its peculiar flavour.
The packages in which sugar is made up are as varied as the sources of supply. West India muscovados are sent over in hogsheads (hdds.), tierces, (trs.), and barrels (brls.). The average net weights of the hogsheads are 10 and 18 cwts. respectively, those of Porto-Rico being the smallest, those of Jamaica the largest; of the tierces, 7 and 10 cwts., and of the barrels, 2 cwts. The clayed sugar of Cuba, called Havana sugar, from the name of the principal port of shipment, is packed in boxes of about 4 cwt. It is the produce chiefly of the north side of the island, the southern side furnishing more muscovado or hogshead sugar. Much of the Brazil crop is packed in cases or chests of from 12 to 18 cwt.; but the more convenient and economical form of bags is superseding the unwieldy packages; the bag weighs about 160 lb. Mauritius sugar is shipped in mats, or bags covered with strong reed or cane matting, of about the same weight as the Brazil bags. East India sugar is supplied in bags of rather less than 2 cwt., that of Manilla in mats of from 50 to 150 lb., and that of Java in baskets or kanasters of from 5 to 6 cwt. The tares allowed on these several packages by the customs and by merchants vary in different places, the merchants' or market tare differing at different ports of the same country.
In the year 1843 the consumption of sugar in the United Kingdom was 202,400 tons; in the year 1859 it was 457,500 tons. In the year 1858 the quantities of unrefined sugar imported into the United Kingdom amounted to 9,010,813 cwts., of the computed real value of L.12,322,405. Of this quantity there were entered for home consumption 8,746,934 cwts. In the same year were also imported of refined sugar and sugar-candy 386,839 cwts., of cane-juice 55,418 cwts., and molasses 77,657 cwts., of which quantities there were entered for home consumption respectively, 257,339 cwts., 57,361 cwts., and 819,226 cwts., the last number including 17,553 cwt. delivered duty free for use in distilleries. The import of the refined sugar was of the computed real value of L.753,681, and of the molasses L.391,787. Raw sugar is entered as of first quality, equal to white clayed; second quality, not equal to white but equal to brown clayed; and third quality, not equal to brown clayed. Of the whole quantity of unrefined sugar imported into the United Kingdom in 1858, rather more than one-third, or 3,628,912 cwts., were from foreign ports, the remainder from British possessions. Of refined sugar and sugar-candy in the same year, 204 cwts. were from British possessions, and 386,635 cwts. of foreign, 326 cwts. of British, and 255,914 cwts. of foreign respectively. The duty on the unrefined sugar entered for home consumption amounted to L.5,848,170. Sugar, whether the produce of British or foreign possessions, being now subject to the same rate of duty, the custom-house entries have ceased to distinguish them, except as the port of shipment serves to indicate their origin. The average price for the year was 29s. 7d. per cwt.
On the continent of Europe the beet-root (Beta vulgaris) is cultivated on account of its saccharine juice being available for the manufacture of sugar. There are many varieties of this plant, such as the large field beet, the disette of the French, and the mangel-wurzel of the Germans. In this variety the flesh, skin, and leaf-stalk are white, the bulb is nearly cylindrical, protrudes much from the ground, and weighs 25 lb. and upwards. There is a sub-variety of a reddish colour, known as long red mangel; another variety of beet is represented by the White Silesian; it is somewhat pear-shaped, with a white flesh and skin, and occasionally rose-red rings in the flesh. Its largest roots do not exceed 5 lb. It abounds in sugar, and the juice is more free from salts and other injurious ingredients, so that it is a favourite with the sugar manufacturers. The three sub-varieties of the White Silesian are distinguished by the colour of the ring presented by a cross-section of the crown close to the bulb. The first is the collet rose, with a rose-red ring; the second the collet vert, with a green ring; the third the collet jaune, with a yellow ring. There is a third group of beet-root known as the globular, of which the yellow globe mangel-wurzel, or Castelnaudary beet is the type. It is pear-shaped, approaching to globular, with the skin flesh-yellow, or passing on into orange, yellowish-green leaf-stalks, and a soft and juicy flesh. It grows to a much larger size than the Silesian, and four sub-varieties of it are recognised. There is a softer variety than the Silesian, known as the Siberian beet; it is of a flattened pear-shaped form, with a white or occasionally rose-red flesh; the bulb grows almost entirely out of the soil, which is a disadvantage, since the part exposed to the action of the sun contains less sugar than the covered portion. All the varieties of beet tend to change their colour, and to become red in the skin and slightly rosy in the flesh; they do not, apparently, differ in chemical composition, although some are better adapted to the manufacture of sugar than others. The collet rose is said to contain the richest and purest juice and is most prized, but the Quedlinburg beet is preferred in North Germany; it is thought to keep better than the Silesian, and its juice to be less acted on by the air. The sugar of the beet is identical with that of the cane; it gradually increases in quantity until the beet is ripe, and by good cultivation, the percentage of sugar may nearly equal that of the sugar-cane. When the flower-stalk begins to form, the percentage of sugar declines; and when the seed is mature, it is almost nothing. Good beet contains, on an average, 10 per cent. of sugar, 3 of pectin, soluble salts, &c., and 83 per cent. of water, thus making 96 of juice, the remaining 4 parts consisting of albumen, woody fibre, and insoluble salts. The juice ferments like that of the sugar-cane, but mannite is produced at the expense of the sugar, and a kind of mucus is formed, which is precipitated by alcohol, and resembles gum-arabic. Beet will grow almost anywhere in the temperate zone, and upon all kinds of soil, but a light rich loam inclining to clay rather than sand is best. Care should be taken in the application of manure, especially of the nitrogenous kind, lest the juice be rendered impure, and the proportion of fermenting azotised matter be increased. The beet-roots may be kept for some months in what are called silos, or shallow ditches dug in the sandy soil, protected from the air by a thatch, and built into trunks of wood in the mass, to serve as ventilating apertures. But there is danger of the sugar passing into the non-crystalline variety. The leaf-stalks and root are removed as soon as the plant is gathered; the former penetrate somewhat deeply into the bulb, and form the heart; this contains very little sugar, but a large proportion of salts, especially nitrates.
When the roots are to be used in the manufacture of sugar, the bruised, decayed, and mouldy parts should be cut away, or the juice may be injured. The bulbs are washed in a large revolving drum, formed of laths or bars of wood partly immersed in water; this gets rid of sand and earth. The axis of the drum is somewhat inclined; the bulbs are fed in at the upper end and pass slowly down to the lower, where they are raised by a scoop and thrown upon a lattice frame. They then pass through a rasping or grating machine, which tears open the cells containing the saccharine juice, and reduces the bulbs to pulp. This machine consists of a drum, the surface of which is thickly studded with teeth, against which the bulbs are pressed, while the drum rotates, and a stream of water plays against them, to prevent them from being clogged. The drum makes 700 or 800 revolutions per minute, and reduces from 300 to 350 cwt. of bulbs to pulp every day while it is in action. The pulp passes into a cistern below the rasp, and is immediately placed in bags of woollen cloth or hemp, and is pressed by means of a hydraulic press. The bags are separated from each other by means of metal plates, or hurdles of plaited willow twigs. After the pressing, from 15 to 20 per cent. of juice remains in the pulp. To recover a portion of this the bags are dipped in water containing 1000th part of tannin in solution, to check fermentation, when the bags swell up to their former bulk, and are again pressed. The juice is collected into a reservoir. The table at which the bags are filled is furnished with a gutter leading to the juice-reservoir, and in some cases the first pressure is made at this table by means of a small hand-press, which expresses 30 to 40 per cent. of the juice. The waste pulp or halm still contains a small proportion of sugar, and is used as food for cattle, mixed with other kinds of fodder. There is also a loss of sugar during the rasping and pressing, in consequence of exposure to the air, and some of the finer particles of the pulp find their way into the juice. Hence an attempt has been made to obtain the juice by maceration, such as cutting the bulbs into thin slices, and digesting them repeatedly in warm water; but the objection is to the great dilution of the juice by this means. Attempts have also been made to dry the beet-root as soon as it is harvested, so as to get rid of 83 per cent. of water; but the expense of fuel is an objection, although the method of manufacturing sugar from cossettes, as the dried fragments are called, is occasionally adopted; but here, again, in proceeding to the manufacture, water, or lime and water, must be added.
As soon as the beet-root juice is obtained, it is raised to the temperature of 140°, and the defecation is conducted by means of hydrate of lime. In order to clear the liquor, an excess of lime is used, and this is got rid of by means of ammonia alum, whereby sulphate of lime is formed, and, the alumina set free, assists the clarification. Pectic acid may also be employed to get rid of the lime, but there is an objection to sulphuric acid which was formerly used, for this converts some of the crystallizable sugar into glucose. The liquor is filtered through charcoal-beds, evaporated at a steam-heat in an open vessel to 25° B., filtered again, and then passed into the vacuum-pan. In evaporating the syrup, various forms of apparatus are in use, some of which take the place of the vacuum-pan, of which kind we may mention the evaporating cone of Lembeck, consisting of a double conical envelope about 16 feet high, heated by steam of the pressure of four or five atmospheres, while the syrup is distributed over the interior by means of a six- or eight-way-funnel, and in descending is divided and distributed by means of hollow conical segments, toothed at the lower edge. The exterior surface of the cone also receives a supply of the syrup which is to be evaporated, and as the syrup descends it increases in strength, and passes by small channels into a trough leading to a cistern. By means of a ball-cock arrangement the syrup is made to flow quicker or slower, according to the rate of evaporation.
The workmen have several kinds of tests for ascertaining the degree of concentration of the syrup. The preuve au filet, or string-test already referred to in the manufacture of raw sugar, consists in taking a drop of syrup between the finger and thumb, and if, on suddenly separating them, it draw out into a thread, the syrup is judged to be sufficiently concentrated; if the thread break and curl up into a little hook, the evaporation is said to have been carried to the preuve au crochet, of which there are two kinds, the weak and the strong. In making sugar-candy there is the preuve au soufflé, or bubble-test, in which a man dips a skimmer into the syrup, and removing it, holds it upright, and blows forcibly through the holes so as to form bubbles of syrup on the other side; if a number of bubbles are blown away, the proof is said to be soufflé fort; if only a few, soufflé léger. In making barley-sugar, &c., the proofs are le petit cassé, le grand cassé, and le cassé sur le doigt. In the first, the moist finger is dipped into the syrup, next into cold water; the sugar is then rolled up into a ball, and this, on being thrown to the ground, splits and loses its shape. In the second proof, the ball is so brittle as to fly to pieces by this treatment, and in the third it solidifies and becomes brittle on the finger. According to M. Payen, the foregoing tests depend upon the following temperatures and percentages of sugar:
| Tests | Temperature | Sugar | Water | |----------------|-------------|-------|-------| | Filet | 228.2° | 85 | 15 | | Crochet léger | 230.9° | 87 | 13 | | " fort | 233.6° | 88 | 12 | | Soufflé léger | 240.8° | 90 | 10 | | " fort | 249.8° | 92 | 8 | | Cassé petit | 251.6° | 92.67 | 7.33 | | " grand | 253.3° | 95.75 | 4.25 | | " sur le doigt | 270.5° | 96.55 | 3.45 |
There are certain points to be attended to in the defecation and clarification of the syrup, or the evaporation will not be successful. If there has been a deficiency of lime, the syrup will froth and foam in the boiling, to remedy which a lump of butter is thrown into the syrup, which spreads over the surface and lubricates the bubbles. If there has been an excess of lime the syrup will not boil, especially if much oxalate of potash be present in the beet. When the syrup is sufficiently concentrated, it is drawn off into coolers or heaters, as the case may be, then passed into moulds, where its treatment resembles that of cane-sugar.
We have referred to an excess of lime being injurious, and it is so chiefly in the mode of getting rid of it. Sugar unites with lime without changing its properties, and may be recovered with little or no loss. This fact has led to several plans for economising the manufacture of beet-root sugar; an excess of lime is employed for the purpose of converting the whole of the sugar into saccharate of lime; and then, after defecation and evaporation, the sugar is re- covered by saturating the lime with carbonic acid, obtained by the combustion of coke and charcoal. The advantages are, great saving in animal charcoal, and the protection of the juice from deteriorating influences.
The secondary products of the manufacture consist of the pulp, as already noticed, while the molasses contain the non-crystalline sugar, various salts, organic matters, gum or mucus, which imparts a nauseous taste; it is occasionally mixed with the refuse pulp, and is given to cattle, or is used in the production of alcohol. The scum, the bone-black, &c., are used as manure.
Although, as already stated, Napoleon I. endeavoured to encourage the manufacture of beet-root sugar in France, it declined after his fall; but in 1826 it revived again. In 1827-8 France produced 4000 tons of beet-sugar; in 1837-8, the production had increased to 39,000 tons; and in 1857-8 to 150,000 tons. In 1858-9 it was 130,000 tons. The French duties, as well as those in Belgium, are charged on the density of the juice as measured by the areometer.
In Germany the sugar-beet manufacture dates from about 1835. In 1858-9 the Zollverein worked up 36,668,557 cwt. of roots. There were 250 refineries in the Zollverein in 1859, of which number 221 were in Prussia. Up to 1853 the customs calculated 20 cwt. of roots as being equal to 1 cwt. of raw sugar. Since that date 15 cwt., and now even 12½ cwt. of roots are considered equal to 1 cwt. of sugar. The present duty is about 8 thalers 22 silbergroschen per cwt., and that from cane as used in the inland refineries 5 thalers. In the Austrian empire the quantity of beet-root worked up in 1859 was 16,042,248 cwt. Here also the system of protection is adopted in favour of beet-sugar.
In Belgium the quantity of sugar produced in 1859 was 18,000 tons. Here, too, there is a protective duty. It is stated that in Russia from 30,000 to 40,000 tons are produced annually.
Another source of sugar is the maple (Acer saccharinum), the sweet juice of which supplies the natives of the United States and Canada with a considerable proportion of their sugar. The juice is collected in February and March, when the sap is most abundant, for which purpose two holes are bored on the south side of the tree, 4 or 5 inches apart, and 18 or 20 inches from the ground. They are made to slope upwards, and not to penetrate more than half-an-inch into the white bark or splint of the stem. Wooden pipes are put into the holes thus formed, and the juice is allowed to flow during about six weeks into wooden troughs, from which it is removed in cans to reservoirs which supply the boiling pans, which are of the capacity of from 13 to 15 gallons. The juice must be removed from the troughs every two or three days, or it will ferment. The boilers are heated over a brisk fire; the scum is removed as it forms, and fresh juice is added to supply the loss from evaporation. The syrup is strained through a woollen cloth, boiled rapidly down in a second pan, cooled, and poured into moulds to crystallize. After the syrup has drained off, the resulting sugar is dry in the grain, of pure taste, and about equal to raw colonial sugar. There is a pleasant maple flavour belonging to this sugar; it finds a ready sale in the United States in the form of small, well-proportioned, square-sided cakes. In good seasons a tree will yield from 3 to 9½ lb. of sugar, and we have seen it stated that one sugar orchard has yielded on an average as much as 6 lb. per tree for 80 years. According to a recent calculation, as much as 27,000 tons of maple sugar are produced in the United States in one year.
Attempts have been made to manufacture sugar from the stems of Indian corn, from the common gourd, and from various kinds of palm. From the last-named source, a juice charged with cane-sugar is known in India as toddy, when fermented and distilled arrack; but by the evaporation of the toddy, the sugar known as jaggery is obtained. The ryots or peasants of India cultivate the sugar-cane, express the juice, boil it down to a thick syrup, which, under the name of goor, is sold to the goldars, who produce the solid product. Other sources of sugar have been proposed, such as chesnuts, the fruit of the Cactus Opuntia, and a species of wild daffodil, Asphodelus.
The Chinese and African sugar-canés, known as the sorgho and imphée (Holcus saccharatus), are the names of graminaceous sugar-bearing plants or millets: they were introduced to European notice in 1786 by Professor Pietro Arduino, of Florence, who attempted to introduce the imphée from Caffreland into Italy, but did not succeed. In 1851 the Count de Montigny, the French consul at Shanghai, sent home some seeds of the Holcus saccharatus; and about the same time Mr Leonard Wray called attention to the same plant as cultivated by the Zoóloo Caffres, not for the purpose of manufacturing sugar therefrom, but for chewing and sucking the stalks. He discovered no less than sixteen kinds of imphée of various degrees of saccharine richness. The plant, however, has been cultivated as a source of sugar in China and Japan from time immemorial, and flourishes most on light sandy soils, and calcareous soils, but particularly on alluvial deposits. It has a tall straight stalk, 16 or 18 feet high, with knots or nodes at intervals, from which spring alternately long spreading, tapering, and drooping leaves. The outer coating of the stalk is smooth and siliceous, like the stalks of maize, and becomes harder as the plant approaches maturity. The seed is formed on the tuft at the top. The soft green pulp undergoes a change of colour as the plant ripens, becoming violet, then brown, and lastly purple, almost black. In this state the maximum of sugar is obtained. The bagasse or crushed stalks should, as in the case of the ordinary sugar-cane, be returned to the soil as manure. The sorgho has been introduced into the United States of America (Sorgho and Imphée, the Chinese and African sugar-canés, by Henry S. Olcott, New York, 1857). Various accounts have been given of its productiveness. A sample grown near Washington yielded nearly 14 per cent. of dry saccharine matter. Mr Wray's plants yielded 16 per cent.; some results are as low as 10, and others as high as 23 per cent. It is stated that an English acre of imphée will, if the circumstances be favourable, yield 2 tons and upwards of dry sugar; but Mr Wray does not estimate the average crop at more than 1½ tons.
The canes are cut as close to the ground as possible, the leaves are stripped off and the tuft removed, and they are carted to the mill as fast as they can be ground. After the crushing, the juice is immediately transferred to the boiler, and heated to about 180° Fahr., an infusion of nut-galls being added. The syrup is then raised to the boiling point, when the fire is suddenly checked, to allow the scum to rise to the surface and be skimmed off, when the heat is again urged until it granulates on cooling. The after-treatment of the sugar has no novelty requiring notice.
The sorgho and the imphée have been introduced into the West Indies, but they are not equal to the canes previously cultivated there. In the United States of America, however, where frosts are destructive to the ordinary sugar-cane, the new plants appear likely to be valuable. In 1857, according to Mr Olcott, 50,000 acres were under cultivation; but unfortunately this gives no information respecting the use of the imphée as a sugar-bearing plant, since much of the seed was sown for the sake of the green crops.
In this brief notice of a vast subject, our attention has been chiefly occupied with technological details. The subject may be profitably viewed from other points of view, such as the political, the commercial, the botanical, the chemical, and even the physiological. For informa- Suharunpoire, a town of British India, capital of a district of the same name, in the N.W. provinces, 1007 miles N.W. of Calcutta, on the small river Dumouloa, about a mile from the Doab Canal. It stands in an open, level, and fertile region; and is surrounded by numerous groves of palms, mangoes, and other trees, which, as they display indications of care and intelligence not common in India, contribute, along with the many British residences in the environs, to give the place a very pleasant appearance, and to render it one of the handsomest English stations in the country. It has a fort, a military cantonment, and a government depot. Here also is a botanic garden, formed in 1817, and now in a flourishing condition, and very tastefully laid out. Pop. (1848) 37,968. The district, which lies between the Ganges and the Jumna, the former dividing it from Garhwal and Bignour on the east, and the latter from Serhond on the west, is bounded on the north by Dehra Dhoon, and on the south by Mozaffarnuggur. Its length is about 68 miles, its breadth 60, and its area 2165 square miles. The surface is very uniform, sloping gradually downwards from the Sewalik Hills in the north, and is only broken by ridges of low sand-hills parallel to the Ganges and Jumna. It is drained by small rivers flowing southwards, and falling into one or other of the great ones which bound the district. Owing to the high latitude and the elevation of the country, the climate is cooler than that of most parts of India, and there is a great range of temperature in the course of the year. The land produces wheat, barley, oats, pulse, and other vegetables, rice, cotton, indigo, and maize. Irrigation is carried on by means of the Doab Canal, which derives its water from the Jumna. Suharunpoire was ceded to the British in 1803. Pop. 801,325.
Suhl, a town of the Prussian monarchy, in the province of Saxony, government and 30 miles S.W. of Erfurt, on the Aue or Lauter. It has several churches, a school, hospital, workhouse, and public offices. In the neighbouring country there are many iron forges, and mills for boring and polishing the metal. Suhl is a centre of the manufacture of arms, and of all sorts of hardware. Woollen and linen cloth, especially fustian, are also made here. Pop. 8892.
Suhm, Peter Frederik Von, one of the most laborious writers of Denmark, was born at Copenhagen on the 18th of October 1728. He is said to have read nearly all his father's library, consisting of some 1500 volumes, before he entered college in 1746. He began the study of jurisprudence, but soon turned aside from the law, even when the brightest prospects in that profession were hurrying him on, to pursue his literary tastes. He began by studying northern history and antiquities; and with that purpose he visited Norway, and remained there from 1751 to 1765. His best writings are—Odin, or the Mythology of Northern Paganism, 1771; the Critical History of Denmark, 4 vols., 1774–81; and the History of Denmark, 7 vols., 1782. He likewise wrote Idylls and Tales with grace and spirit. These will be found in his Samlaide Skrifter, 16 vols., 1788–99. His benevolence was as conspicuous a feature of his character as his immense literary industry. His great library, consisting of 100,000 volumes, he threw open to the public, and he consented that it should be united to the royal library a short time before his death, which took place on the 7th September 1798.