the pores. The sugar is next removed from the moulds and placed in a stove heated by steam, for four or five days, or until thoroughly dry, when it is fit for the market.

Beetroot-sugar. The process for the manufacture of sugar from beetroot is as follows: The roots are first washed, and then freed from the crowns, as well as from any decayed portion. They are then either crushed or subjected to what is called the "diffusion process." If the first plan be adopted, the roots are placed in a machine containing a large drum, the circumference of which is set with a number of saw-blades or teeth. This drum rotates, and as the roots are passed through they are rasped into a pulp, which falls into a cistern or hopper, where the juice is separated by pressure. In the diffusion process, the cleaned roots are sliced and placed in warm water for a time. The mixture of juice and water thus formed is then run into a second vessel containing more sliced roots, and so on to a third and a fourth, by which time it generally becomes sufficiently concentrated. The juice thus obtained is treated in the same way as the product of the crushing operation-that is, it is first heated with milk of lime to a temperature of 140° to 150° F. (60° C. to 66 C.) in order to clarify it, and, the scum having been removed, carbonic acid is forced into it to precipitate any lime which has been dissolved in the syrup, and in doing which it also carries down with it a quantity of colouring matter. The next operation is to pass the juice through animal charcoal, after which it is put into a vacuum-pan heated by steam, and evaporated to a syrup, having a specific gravity of from 1200° to 1*300°, and containing from 45 to 60 per cent. of sugar. The methods adopted for obtaining pure sugar from this syrup do not differ essentially from those employed in refining the product of the sugar-cane. The refiner of beet-sugar, however, finds his syrups to contain a much larger quantity of potash salts, which it is his object to leave behind as completely as possible in the mother liquor, from which his last crystallization of sugar has been obtained.

Maple-sugar. The sugar-maple, Acer saccharinum-a tree abun

dant in the forests of North America-is a valuable source of sugar to the inhabitants in the interior of the Northern States. The tree is tapped in the spring of the year, and the sap which runs from it collected in vessels, and boiled down to the crystallizing point and strained, after which it is poured into moulds to solidify, and is then ready for use.

Jaggery. The sugar called "Jaggery," the product of various palm-trees, supplies the wants of a large number of the inhabitants of India. It is imported into this country, but is perhaps the lowest quality in the market, and is unfit for domestic purposes in its raw state, and, from the large proportion of invert-sugar contained in it, commands a very low price from the refiner. It however exercises an important influence in controlling the value of raw sugar in times of scarcity.

Molasses, etc.-The mother liquor left in the crystallization of raw sugar is called Molasses; that in the crystallization of refined sugar, Treacle, or Golden Syrup. These vary in composition, but contain some cane-sugar along with invert-sugar. The invention of the vacuum-pan-which is simply a means of boiling at a temperature lower than the boiling-point of the liquid at the ordinary pressure of the atmosphere-has largely reduced the amount of treacle and molasses produced in sugar manufacture. The treacle or molasses from beet is not considered fit for domestic use, and is therefore usually disposed of to the distiller to be converted into spirit.

Glucose. The production of glucose from grain, or other substances containing starch, is now carried on extensively in this country, and the sugar made is almost exclusively used as a substitute for malt in the brewing of beer. There are at least two processes followed. In the first, the grain, being ground and separated from the husk, is thrown into a mixing-vat with about four times its weight of water, and from 2 to 4 per cent. of its weight of sulphuric acid according to the nature of the substances used. This mixture is then passed into what is called a converter, where it is boiled for from twenty minutes to half an hour under

a pressure of about 70 lb. of steam, corresponding to a temperature of about 306° F. (152° C.), by which the starch is changed into glucose or dextrose. Chalk is added to remove the sulphuric acid, and, after filtering, the syrup is partially evaporated in a vacuum-pan, and run through a column of charcoal to decolourise it. The next process is to boil it down to the necessary consistence in a vacuumpan, under such a pressure that the boiling shall take place at a temperature not exceeding 150° F. (65.5° C.) It is lastly run into moulds and allowed to cool, when it becomes perfectly solid, and is then ready for the market. On the Continent this variety of sugar is also made from potatoes, the process of conversion being essentially the same.

The second mode of manufacture is to treat 100 parts of grain, or other substance containing starch, with 40 parts of water and 3 parts of sulphuric acid. This mixture is allowed to stand for twenty-four hours in the cold, and then heated for about three minutes in the converter under a pressure of 65 lb. of steam. The removal of the sulphuric acid, the filtering and concentration, are then effected as before described; but by this process the conversion of the starch into glucose is not so complete as by that first given.

Maltose is the name given to an article prepared from starch by the action of malt-extract. It differs in character from dextro-glucose in its optical properties, having a dextro-rotatory power of 150o, that of dextro-glucose being 56°. It also differs in its cupricoxide reducing power, which is about 62 per cent. of that of glucose. Dubrunfaut, the French chemist, was the first to regard this as a distinct sugar, but we are indebted largely to the labours of O'Sullivan for what we know in regard to it. Previous to the researches of these chemists it was considered to be a mixture of dextro-glucose and dextrin, and some of its chemical reactions favoured this view of its constitution.

Lavulose or Lavoglucose is a colourless uncrystallizable syrup as sweet as that of cane-sugar, and contained in equal proportions with dextro-glucose in invert-sugar. Its distinctive property is the

power it possesses of turning the plane of polarisation to the left, and hence its name. This rotatory power, unlike that of dextroglucose, varies very considerably with the temperature, being 106° at 57° F. (14° C.) and only 53° at 196° F. (91o C.) It is formed along with dextro-glucose by warming a solution of cane-sugar with dilute acid; by leaving it exposed to the air for a time; or by exposing it to the action of yeast. It exists with dextro-glucose in honey and many fruits, and is also found in treacle and molasses, which, as already stated, are mixtures of invert and cane sugars.

Mannitose is the sugar derived from manna, from several seaweeds, and from mushrooms. To prepare it, a substance called Mannite is dissolved out of manna by boiling alcohol. This is oxidised, in presence of platinum black, into mannitic acid and mannitoṣe, and the mannitic acid is removed by means of lime, with which it forms a compound insoluble in alcohol.

Besides all these there is another sugar derived from milk, named "Lactose," which, however, will be more fully referred to under the head of Milk.

History. The word sugar is probably derived from the Sanscrit word sarkara, which in the Persian became shukkur. It is supposed by Humboldt to have been known to the Chinese in very early times, and it is not improbable that it was in use by the ancient Jews, and that the Hebrew word occurring frequently in the Old Testament, sometimes rendered "calamus," and sometimes "sweet cane," has reference to it. Sugar is mentioned occasionally by the early historians as "honey from reeds," "saccharon," etc., and many medicinal properties are by them ascribed to it. Its introduction into Europe for dietetic purposes was in some measure due to the Crusaders. There can be little doubt but that the sugar-cane is natural to many islands in the West Indies, as well as to parts of South America, but it appears to be equally clear that the natives were not acquainted with the means of extracting sugar from it until after the Spanish and Portuguese colonisation. So quickly, however, did the manufacture spread that, according to the testimony of Oviedo, no fewer than thirty

sugar-mills were established in Hispaniola (St. Domingo), in 1535; and in the island of St. Thomas (Portuguese), in 1620, there were seventy works, each employing not fewer than 200 slaves, and forty ships being loaded yearly with the produce. We find that, in 1726, the French produced 33,000 hogsheads of sugar in St. Domingo, in 1742, 70,666 hogsheads; and in Martinique, Guadaloupe, and the lesser isles, 51,875 hogsheads. The whole produce of the British West India Islands imported into Great Britain was 60,950 hogsheads, but at this time the East Indies had been opened out by the enterprise of the East India Companies, and we were obtaining a large supply from that quarter of the globe.

The art of refining sugar began to be practised in England in 1544.

The consumption of sugar in Great Britain in 1700 was estimated, according to McCulloch, at 10,000 tons; in 1790 it had reached 81,000 tons; in 1808, although the duty had been gradually raised from 3s. 5d. per cwt. (the rate during Queen Anne's reign) to 275., the consumption had increased to 142,000 tons. It fell during the Napoleon wars to 100,000 tons, and from that time there has been a steady increase, the amount in 1867 being 546,000 tons. The imports in 1877, including beet-sugar, were 1,003,161 tons; and in 1880, 1,001,285 tons.

The discovery that beetroot contained sugar identical with that obtained from the sugar-cane, was first made known by Margraf, in 1747. The culture of the beet for the purpose of sugar manufacture did not, however, make much progress during that century, and it was mainly in consequence of the policy of Napoleon that it could be said to have come into competition with the product of the sugar-cane. From the peace of 1815 to the year 1860 it passed through many vicissitudes; and, even after the latter date, it was confidently affirmed by refiners in this country that beet-sugar could not be deprived of the peculiar flavour attaching to beetroot itself, and on that account would never be a dangerous rival in this country to the product of the