Page:The New International Encyclopædia 1st ed. v. 18.djvu/778

* SUGARS. 676 SUGARS. The synthesis of each one of these bodies was accomplished by a series of complicated reactions wliieh are fully described in text-books on chem- istry. Fischer's work was greatly facilitated by the use of plienylhydrazine, which forms readily crystallizable compounds with the hexoses, called osazones. These compounds are insoluble in water and erainentl}' suited for the separation and identification of the different sugars. By means of the cyanhydrine reaction he changed hexose sugars into heptoses, and these in turn into octoses and nonoses. The combination of monosaccharides to form disaccharides has only recently been accomplished by Fischer. Among a number of his synthetic disaccharides is one which he designates galactosidoglucose (because it is made by the imion of one molecule of d-galactose with one molecule of d-glucose), and which closely resembles the natural sugar meli- biose. In an article published in September. 1902. he says that if further investigations eon- firm his conclusion that the two sugar* are iden- tical, "melibiose is the first natural disaccharide to be produced synthetically." The more important sugars are mentioned in the following table with brief descriptions of their success : 1. Monose. CHjO. ■2. Biose, CHjO,. 3. Ti-iose, CjHjO,. 4. Tetrose, C.HjO,. 6. Pentoses. C^HioOj A. Aldopentoses. B. Ketopentoses. C. Methyl peiitoaes, 6. Hexoses. CoH,,Oe. A. Aldohexoses. B. Ketobesoflee. C. Hexoses o! natu- ral origin and of unknown nature. D. Methyl hexoses, CH,C,H,,0.. 7. Heptoses, C,H,,0,. 8. Octoses, C,H,„0,, 9. Nonoses, CjH,sO„ I. Monosaccharides Formic aldehyde. Glyeolllc aldehyde. Glycerose. obtained by oxidation of glycerin. Erythrose. obtained by oxidation of erythrin, a tetrahydric alco- hol found in lichens and algEe. 1-arabinose (arabinose, arabose. peetinose, pectin-sugar) and xlk'lose (wood-sugar), obtained alone or mixed with other sugars by hydrolysis of gums and other vegetable substances. d-ara.binose. 1-xylose, and ribose, obtained .'fyntheticall.v. None known with certainty. Fucose. from seaweed: rhamnose, widely distributed iu the vege- table kingdom in the form of glucosides ; chinovose, obtained b.v the decomposition of chino- vite, a constituent of cinchona bark. d-g!ucose (dextrose, grape sugar or starch sugar), see Glucose; d-mannose (mannose. isoman- nose or serainose), obt.ained by the oxidation of mannite and by the hydrolysis of various vege- table materials; d-galactose (see below). l-glucose, 1-niannose, 1-galactose, d-gulose. 1-guIose, d-idose, 1-id- ose, d-talose, and 1-talose, ob- tained syntheticall.v. d-fructose (levulose or fruit sugar; see below); sorbinose, from mountain ash berries. I-fructose, obtained synthetically. Chondroglucose, crocose, eucalyn, hederose, indiglucin, locaose, paraglucose, phlorose. ecammo- nose, skimminose. solanose, tew- tlkose (forms 5 to 6% of the milk of the Egyptian buffalo), and wine sugar. a-rhamno-hexose and /3.rhamno- hexose, obtained synthetically. Six heptoses and a methyl deriva- tivehavebeen prepared synthet- ically. Four octoses and a meth.vl deriva- tive have been prepared in the laborator.v. Two have been produced artifici- ally. 2. Derivatives of hex- Sucrose (cane sugar, saccharose, OSes, CijHj^On. saccharon, or saccharobiose), lactose (milk sugar, lacbobiose. or lacton), and liialtose (malto- biose, malt sugar, amylon, dl- glncou. ptyalose, r cerealose); see below). Trehalose (mycose, .trehabiose) from ergot and other fungi ; isomaltose from malted grain ; melibiose, formed together with d-fructose by careful hydrolysis of raffinose : turanose, formed together with d-glucose by hydrolysis of melecitose; cyda- mose, from cyclamen tubers ; agavose, from the juice of the agava; and several produced synthetically by Fischer. III. All are derivatives of the hexoses, II. 1. Derivatives of pen- toses, C,„H„0„. Disaccharides Di-arabinose or arabinon. ob. tained from arabinic acid (meta- pectic acid). Trisacchabides Rattinose (melitriose, nielitose, goesypose, or cotton sugar; see below); melecitose (melecitriose), from the manna of I'inus Iiirix ; Btachyoee, from the tubers of Stachys tuberifera ; gentianose, from the roots of Gentiann. lutea; lactosinose (lactosin), from the roots of certain plants of the order Caryophyllaceje ; and sec- alose, from unripe rye. Sucrose, Cane Sugar, oe Saccharose. This is commercially the most important sugar. It and the products of its hydrolysis, 'invert sugar,' and the sugars that compose 'invert sugar' (d-glucose and d-fructose) are the most impor- tant sugars, considered from the point of their wide distribution in fruits and vegetables used for food by man and the lower animals. (For the commercial sources of cane sugar, sec Sugar, Manufacture of.) White granulated sugar, whether made from sugar-cane or beet roots, contains between 99 and 100 per cent, of pure sucrose or cane sugar. In many plants it is found associated with 'invert sugar,' which seems to be changed to cane sugar during tie process of ripening. When cane sugar is hydro- lyzed by the action of acids or enzymes, each molecule yields one molecule of d-glucose and one molecule of d-fructose. a mixture called 'invert sugar,' as explained above. Cane sugar is readily crystallized in the form of monoclinic hemiliedral tables which contain no water of ci-ystallization. These crystals are well exemplified in loaf sugar, rock candy, and granulated sugar, the coarseness of which de- ])cnds upon tlie size of the crystals. It dissolves in about one-half of its weight of water and is much more soluble in hot water; it is dissolved with diiiicultv in strong alcohol. Its specific gravity is 1.006. It melts at 160° C. (320° F.), and with care may be cooled to a colorless glass- like mass; if the temperature is somewhat higher the solidified mass is colored and constitutes the so-called 'barley sugar.' At 200° C. (392° F.) decomposition and marked coloration begin, cara- mel is formed, and as the heat is continued gases are evolved and finally only a black cliar re- mains. Sucrose unites with the oxides of cal- cium and other metals to form saccharates, which are of importance as a means of separating sugar from beet-root molasses. While cane and other sugars in dilute solutions are very prone to vmdergo fermentation and change, they pos- sess considerable antiseptic power in concentrated solution, which is utilized in dried fruits, pre- serves, etc. Levulose, d-FRUCTOSE, or Fruit Sugar. This occurs in almost all sweet fruits with d-glucose.