Cane Sugar colourless, inodorous, of a purely sweet taste, moderately hard, and brittle. The crystals, when rapidly formed, as in common refined sugar, are small ; but when obtained by the slow evaporation of a strong solution, they are of considerable size (sugar candy). The specific gravity of sugar is about 1*6 : it under goes no change by exposure to the air ; and, when moderately heated, loses only a little hygrometric moisture : it is soluble in one-third of its weight of cold water, and in all proportions in hot water : a solution saturated at 230° forms, on cooling, a mass of small crystals. It is soluble in alcohol, but much less so than in water ; absolute alcohol takes up only 1-80th of its weight, even when boiling, aud this sepa rates in small crystals as the solution cools : spirit of wine, of specific gravity 0.830, dissolves nearly one-fourth of its weight. Sugar is phosphorescent when two pieces are rubbed together in the dark. Heated to about 320° Fahr., sugar melts into a viscid colourless liquid, which, cooled suddenly, becomes a transparent mass (barley-sugar); by keeping, it becomes opaque. At 400° to 420° sugar is converted into CARAMEL, or burnt sugar two equivalents of water being set free. When exposed to a higher temperature, sugar undergoes decom position, yielding various gaseous products, and leaving a large pro portion of charcoal. Acids produce very different effects upon sugar : thus nitric acid decomposes and is decomposed by it, the principal products being nitric oxide, carbonic, oxalic, and saecharic acids : sulphuric acid, when concentrated, attacks sugar itself, or even a strong solution of it, sulphurous and carbonic acid gases being formed and evolved, and a large quantity of carbon set free ; I-100th of a grain of sugar, on account of the large proportion of carbon which it contains, is capable of imparting colour to an ounce of sulphuric acid. When sugar, dissolved in dilute sulphuric acid, is kept for a long time at a high temperature, it absorbs oxygen from the air, formic acid is produced, and there is deposited a brown insoluble matter termed ulmin. Ulmin is sometimes formed when recently expressed cane juice is heated, a small portion of lime, however, neutralises the acid in the juice, and prevents its formation. Hydrochloric acid dissolves sugar, and forms with it a thick black resinous paste. A simple solution of sugar in water undergoes change slowly when exposed to the air, but on the addition of yeast it undergoes rapid fermentation, and is converted, first into grape-sugar, and then into alcohol.
Sugar in many cases combines with the alkalies, earths, and metallic oxides, and, in some cases, forms definite compounds with them called saccharates, or saccharides. With ammonia, according to Ber zelius, sugar combines to form a compound of one equivalent of each ; but by exposure to the air the ammonia escapes, and leaves the sugar unaltered : potash and soda appear also to combine with sugar, and they destroy its sweetness ; this is restored when the alkalies arc satu rated with an acid : but if they be left long in contact, the sugar becomes changed into a substance resembling gum.
Lime, baryta, and oxide of lead dissolve in considerable quantity in a solution of sugar : when the first-mentioned of these bodies, in the state of hydrate, is digested at a moderate heat in a solution of sugar, a bitter alkaline solution is obtained, in which the sugar is combined with an equivalent of lime (CaO, C„Ii„0„). Professor Daniell obtained,
by the action of these bodies, gum aud crystals of carbonate of lime.
The compound of sugar and baryta is similar. Irlien hydrated oxide of load is digested in a solution of sugar, a yellow alkaline liquid is funned, which yields a tough deliquescent mass by evaporation ; but when excess of the oxide ra boiled in a solution of sugar, and the liquor is filtered hot, it deposits eventually a tasteless insoluble com pound, containing 2 PbO, Sugar dissolves carbonate and diacetats of copper, forming green solutions which are not decomposed by the alkalies, and this is also the case with the mita of iron. A crystalline compound of sugar and CoMMOLI milt may be formed by the spontaneous evaporation of n solu tion of four parts of the former and one part of the latter. According to Peligot it contains NaCe,110,C,,11„0,+ C,,Il Distilled with eight times its weight of quicklime, sugar furnishes Mr:vac-moss. Chlorine transforms sugar into a brown substance partially soluble in water.
For the action of solutions of sugar on a ray of polarised light, and estimation of the strength of a solution of sugar, see SACCIIADIMETRY.
The uses of cane sugar are too well known to require much 'reties : ore account of its antiseptic power, it is employed to preserve various vegetable products : It is used as a sweetener of many kinds of food, and is in these canes nutritious; but being destitute of nitrogen it is, like other substances similarly constituted, incapable of supporting life for any length of time.
pie Sugar, when refined, is equal in appearance and sweetening power to refined cane-sugar ; and in composition they are similar. flat-root Sugar is exactly similar to cane-sugar.
Grape-sugar, or glucose 2AI.), or starch-sugar. Besides the sources previously mentioned, this variety of sugar has been lately shown to be a constituent of healthy urine. Under the name of diabetic sugar it occurs in abnormal quantities in the urine of patients afflicted with diabetes ; under these circumstances it is readily detected on adding to a small quantity of the urine contained in a test-tube, first, solution of potash or soda, next a few drops of solution of sulphate of copper, and then ,gradually heating to the boiling point, when an abundant deposit of red suboxide of copper will be formed if sugar be present in abnormal quantity. The same test may, of course, be applied to any other solution suspected to contain glucose.
Grape-sugar is produced in quantity by allowing a cream of starch and water to flow into water containing one per cent. of sulphuric acid, at a temperature of 130° Fahr. The whole is ultimately boiled far a short time, the sulphuric acid neutralised by chalk, and the solu tion evaporated down and set aside to crystallise.
Glucose forms combinations with bases which are rapidly decom pdsed, yielding GLIXIC ACID. When heated, they yield uncrystallisable 3IsLasste Amp. Combinations of glucic acid with certain crystalline principles occur naturally ; several are described under Gtucosines.