SUGAR, is the sweet constituent of vegetable and animal products. It may be distinguished into two principal spe cies. The first, which occurs in the su gar-cane, the beet-root, and the maple, crystallizes in oblique four-sided prisms, terminated by two-sided summits ; it has a sweetening power which may be repre sented by 100; and in eircumpolarization it bends the luminous rays to the right. The second occurs ready formed in ripe napes and other fruits ; it is also pro duced by treating starch with diastase or sulphunc acid. This species forms cauli flower concretions, but not true crystals ; it has a sweetening power which may be represented by 60, and in circumpolari zation it bends the rays to the left. Be sides these two principal kinds of sugar, some others are distinguished by chem ists; as the sugar of milk, of manna, of certain mushrooms, of liquorice-root, and that obtained from saw-dust and glue by the action of sulphuric acid ; but they have no importance in a manufacturing point of view.
Sugar, extracted either from the cane, the beet, or the maple, is identical in its properties and composition, when refined to the same pitch of purity ; only that of the beet seems to surpass the other two in cohesive force, since larger and firmer crystals of it are obtained from a clarified solution of equal density. It contains 5•3 per cent. of combined water, which can be separated only by uniting it with oxide of lead, into what has been called a saccharate ; made by mixing syrup with finely ground litharge, and evaporating the nuxture to dryness upon a steam bath.• When sugar is exposed to a heat of 400° F., it melts into a brown pasty mass, but still retains its water of compo sition. Sugar thus fused is no longer capable of crystallization, and is called caramel by the French. It is used for
coloring liquors. Indeed, sugar is so susceptible of change by heat, that if a colorless solution of it be exposed for some time to the temperature of boiling water, it becomes brown and partially unerystallizable. Acids exercise such an injurious influence upon sugar, that after remaining in contact with it for a little while, though they be rendered thor oughly neutral, a great part of the sugar will refuse to crystallize. Thus if three parts of oxalic or tartaric acid be added to sugar in solution, no crystals of sugar can be obtained by evaporation, even though the acids be neutralized by chalk or carbonate of lime. By boiling cane sugar with dilute sulphuric acid, it is changed into starch sugar. Manufactu rers of sugar should be, therefore, parti cularly watchful against every acidulous taint or impregnation. Nitnc acid con verts sugar into oxalic and malic When one piece of lump sugar is rubbed against another in the dark, a phospho rescent light is emitted.
Sugar is soluble in all proportions in water ; but it takes four parts of spirits of wine, of spec. gray. 0.860, and eighty of absolute alcohol, to dissolve it, both being at a belling temperature. As the alcohol cools, it deposits the sugar in small crystals.• Caramelized and unerys tallizable sugar dissolve readily in alco hol. Pure sugar is unchangeable in the air, even when diSSolved in a good deal Of water, if the solution be kept covered. and in the dark; but with a very small ad dition of gluten, the solution soon begins to ferment, whereby the sugar is decom posed into alcohol and carbonic acid, and ultimately into acetic acid.