"Refined sugar is seen in commerce broken into small pieces or lumps, which are hard and have a granular crystalline texture and a pure white color. Somewhat inferior kinds of sugar are softer, and those having a yellowish tint are often artificially improved in appearance by adding, while crystallizing, a minute quantity of blue pigment, like ultramarine, with the view of neutralizing the objectionable tint and making the sugar appear whiter; such sugar will yield a yellowish solution with water, and on standing will gradually separate the pigment. Perfectly white sugar, known in commerce as double refined, is the only kind that should be used. Sugar may be obtained in large transparent rhombic prisms, known as rock candy, saccharum candidum, which does not differ from lump sugar, except that this is in crystalline masses from disturbed crystallization. Sugar having the specific gravity of 1.58 (Kopp) is permanent in the air, neutral, without odor, has a very sweet taste, and dissolves at ordinary temperatures in one-half its weight of water, yielding a dense, sweet, and. colorless liquid known as syrup. At the boiling-point sugar dissolves in water almost in all proportions (in 0.2 parts, U. S., 0.212 parts, Flourens). It requires for solution about 80 parts of boiling absolute alcohol, 28 parts of boiling officinal alcohol, and about 4 parts of boiling alcohol, specific gravity .830, these solutions depositing most of the sugar on cooling. The solubility is greater in weak alcohol, both cold and hot. At 15° C. (59° F.) 1 part of sugar dissolves in 2 parts of 50 per cent, alcohol, in 31.6 parts of 85 per cent, alcohol, in 175 parts of 92 per cent, alcohol, and in 228 parts of methylic alcohol of the same strength (Casamajor). Sugar dissolves also in glycerine, the solubility being increased on dilution with water, but it is insoluble in ether, chloroform, carbon disulphide, and in hydrocarbons. It combines with chloride of sodium, yielding deliquescent crystals, which contain 14.9 per cent, of that salt. Definite compounds have likewise been obtained with several other salts, and with alkalies and alkaline earths. When triturated in the dark it becomes luminous. Its solution deviates polarized light to the right, a behavior which is of great practical importance for the estimation of sugar in aqueous liquids, and for distinguishing different kinds of sugar, which have a different rotary power.
"When sugar is heated to 160° C. (320° F.) it melts without losing in weight, and congeals on cooling to a transparent, amorphous, yellowish mass, known as barley-sugar, saccharum hordeatum, which becomes gradually opaque on the surface from the formation of minute crystals. If sugar is kept in the melted state between 160° and 170° C. (320° and 338° F.) for a short time, it is converted into a deliquescent mixture of glucose and levulosan; C13H18O11 yields C6H12O6+C6H12O5; the latter is not fermentable until after it has been boiled with water or dilute acids. When heated to between 180° and 200° O. (356° and 392° F.), sugar turns brown, evolves a peculiar odor, and is converted into caramel, C12 H18O9, parting at the same time with 2H30. (See Chapter on "Sugar Color," later on.) Subjected to dry distillation, sugar yields aldehyd, acetone, acetic acid, tarry products, and carbonic acid, carbonic oxide, and marsh gas. According to Lassaigne, iodine heated with solution of sugar is converted into hydriodic acid. Under the influence of ferments, as well as of dilute acids, cane-sugar is converted into invert-sugar, which is a mixture of dextrose or grape-sugar and levulose or fruit-sugar, and is directly fermentable.
This inversion of sugar takes place slowly on boiling with water, but cold aqueous solutions keep unaltered for a long time, provided the access of ferments suspended in the air be prevented. Under the same condition, according to the investigations of Kreusler, Lemoine, and others, light does not exert the inverting effect reported by Raoul (1871), Nitric acid inverts cane-sugar readily; and when heated with it produces saccharic, racemic, tartaric, and oxalic acids"