Dextrose (C,H„06) rotatea a ray of polarized light to the right. It may be obtained io the form of needle-shaped crystale by the evaporation of an alcoholic aolution ; when freshly prepared, its rotatory power is 112', but after standing for some time, or immediately on heating, the rotation ainka to 56°, and remains constant; it is insoluble in ether, soluble in alcohol, and gives no coloration when mixed with concentrated sulphuric acid ; with alkalies, on the application of heat, it turna brown ; it reduces an alkaline solution of a cupric salt, and forms with metallic bases, compounds called glueoaates; when heated to 170° (338° F.), it gives off one atom of water ; by increasing the temperature, it turns brown, and is subsequently converted into caramel.
Ltevulose is isomeric with dextrose, but rotates a ray of polarized light to the left ; its molecular rotatory power, which varies with the temperature, according to Dubrunfaut, is [a] j = —53° at 90° (191° F.), — 79.5 at 52° (125.6° F.), — 106 at 14° (57.2° F.). It is a colourless, unerystal lizable syrup ; on the application of heat, it behavea much in the same way as dextro-glucose. It may be prepared by inverting canc-augar with hydrochloric acid, and adding excess of calcie hydrate ; the liquid after some time solidifies, and the solid mass, wheu aubtnitted to pressure, yields a solution of a calcium salt of dextro-glucose together with calcium chloride ; after washing the cake of Itevo-glucose with water, and treating with oxalic acid, a solution of ltevo-glucose is obtained.
Maltose, according to O'Sullivan, is a crystalline body yielding 50 per cent. of its weight of alcohol when fermented with yeast. It is formed by the action of malt-extract on atarch ; its specific rotatory power is twice that of cane-augar (147.6). 100 parts correspond to 77.32 of cuprio oxide, being equal to 65 parte of invert sugar. By boiling with acids, it is converted into dextrose.
Those members of the third group (isomeric saecharoses) which are objects of manufacture will be described in detail under their special heads; others are dealt with under Drugs—Ergot, p. 810, Manna, p. 818.
It may here' be explained that " barley-sugar " is pure sugar melted by heat, aod allowed to eolidify to au amorphoua Illa89 instead of oryatallizing. " Sugar-candy " is a solution of sugar crystallized by very slew evaporation, the crystals being unusually large, and centred around threads auspended in the liquid for the purpose of forming nuclei. " Molasses" is the dark coloured, impure liquid, consisting of a mixture of crystallizable and uncrystallizable sugar, coloured by earamel (see pp. 598-9), and containing the greater part of the organic matters separated in the processes of making and refining cane- and beet- sugars. " Syrup" or " golden eyrup " is the molasses obtained by washing and " machining" the higher classes of refined auger.
" Glucose" is applied commercially only to artificial starch-sugar; in analysis, it signifies all uneryatallizetble sugar found in cane-sugars : to avoid confusion, the term " uncrystallizable sugar " will be employed throughout this article to denote all forms of uncrystallizable or very slightly crystallizable sugar —(the very weak crystallizing power of dextrose and helm:dose causes them to be called un-crystallizable)—met with or prodtwed in the course of preparing crystallizable auger, and the special terms glucose, starch-augar, will be reserved for their special application. The commercial sugara, whose production and manufaclure will receive detailed description in this article, will take the following order :—Beet-sug,ar, Cane-sugar, Maplc-sugar, Melon-sugar, Milk sugar, Pt:lin-sugar, Sorghum- and Maize-sugar, Starch-sugar aud other Glueoses. These will be followed by sectious on Sugar-refiuing, Summary of Patents, Analysis, Production and Commerce, Bibliography.
(FR., Sucre de Betteraves; GER., Rilbenzucher). Cuvrivarrow.—The beetroot (Beta vulgaris), indigenous to Europa, is cultivated in France, Germany, Belgium, Holland, Scandinavia, Austria., Russia, and to a very small extent in England, and recentlir established in Canada, the United Statea, and New Zealand. There are many varieties. The most important to the sugar maker is the white Silesian, sometimes regarded as a distinct species (B. alba); it shows very little above ground, and penetrates about 12 in.; it has white flesh, the two chief forms being distinguished by one having a rose-coloured skin and purple-ribbed leaves, the other a white skin and green leaves. Both are frequently grown together, and exhibit no marked difference in sugar-yielding qualities.
Good sugar-becta possess the following broad characteristics :—(1) Reg,ular pear-shaped form and smooth skin : long, taperiog, earrot-like roots are considered inferior ; (2) white and firm flesh, delicate and uniform structure, and clean sugary flavour : thick-skinned roots are spongy and watery ; those with large leaves are generally richer ; (3) average weight li-2i lb., neither very large nor very small roots being profitable to the sugar-manufacturer ; as a rule, beets weighing mere than 3i lb. are watery, and poor in sugar ; and roots weighing less than lb. are either unripe or too woody, and in either case yield comparatively little sugar ; the sp. gr. of the expressed juice, usually 1.06-1.07, even reaching 1.078 in English-grown roots, indicating over 14 per cent. of crystal lizable sugar, is the best proof of quality ; juice poor in sugar has a density below 1 .060 ; (4) in well-cultivated soil, the roots grow entirely in the ground, and throw up leaves of moderate size.