The second group of sugars, namely, those which are incapable either directly or in directly of undergoing fermentation, are of less practical importance than cane sugar, grape-sugar, or milk-sugar.
/wain, or inosite (derived from the Greek is, gen. (nos, muscle), is represented by the formula Ci2Hia0i2 4Aq. It occurs as a normal constituent in the juice of the heart, and of the involuntary or unstriped muscles, and has also been found in the tissues of the lungs, spleen, liver, kidneys, and brain, and in the urine in Bright's disease and dia betes. It has been recently shown that it is identical with the substance previously known as pluiseo-mannite, which is readily obtained from the unripe seeds of the com mon kidney-bean (phaseolus vulgaris). It forms colorless efflorescent prisms, which lose four equivalents of water at about 210°. When mixed with decaying cheese and chalk, it becomes gradually converted into lactic and butyric acids. Scyllite is a saccharine matter closely resembling inosite, and occurring in various organs of several plagiostom ous fishes, and especially in the kidneys of the rays and skate. It differs, however, from inosite in its crystalline form, and in its containing no water of crystallization. Its composition is unknown. Sorbin, or sorlrite (C19111;022), derives its name from its oc currinff in the juice of the berries of sorbus aucuparia, the service tree, and may be obtained in colorless transparent rhombic octahedra. It reduces oxide of copper to the suboxide (Trommer's test), and is of a sweetish taste.
Closely allied to the sugars, but differing from them in their chemical composition (inasmuch as they do not contain hydrogen and oxygen in the proportions to form water), are marmite (Cialli40,2), obtained from manna, the inspissated juice of the fraxinus ornus, but also occurring in celery, onions, asparagus shoots, laminaria saccharata and other sea-weeds, certain fungi, the juice which exudes from apple and pear trees; dulcite (Cialli 40 2), the product of an unknown Madagascar tree; quercite (C12E1120,0), obtained from acorns; and pinite (Ci21L20,o), from pinus lambertiana, a tree growing in Aus tralia and California. All these bodies are crystalline, and sweet to the taste.
Although chemists have hitherto looked upon the sugars as organic compounds, with out any recognizable radical, and from their composition have termed them carbo hydrates, " the researches of Berthelot render it probable that the sugars as well as marmite, and the bodies allied to it, are polyatomic alcohols, like glycerine, for he has found that they possess the power of entering into combination with various acids, with elimination of water, in some cases yielding colligated acids analogous to the tannic, and in others furnishing neutral bodies, closely allied to the fats." Miller's Organic Chemistry,
2d ed. p. 72.
Among the various chemical purposes to which the phenomenon of circular polari zation may be applied, we may especially mention its use in determining the quantity of any kind of sugar in solution. While some sugars give a right-handed rotation, others give a left-handed rotation, and each sugar exerts a definite amount of rotatory power. following are the rotatory powers of the chief varieties of sugar, equal weights of each being dissolved in an equal bulk of water, and the temperature being 56° : Cane-sugar (Ciall,101) right 73° '8 Trehalose (C,2Hii011) " 220° Melezitose 0 i) .1 Mycose (C1.1111011) " 193° • Inverted sugar (C1211'20'2) left 28° Grape-sugar (C,2112011) right 57°'4 Milk-sugar (C12111201) " 56° Sorbin (C12E112012) left 46°•9 • For details regarding the apparatus to be employed, and the method of using it, we may refer to Miller's Cheini0 Physics, 3d ed. p. 204; and to a memoir by Clerget in the Ann. de Chimie, iii., xxvi. 175. This method has been applied to determine the amount of sugar in diabetic urine, to ascertain the quantity of sugar which remains in the unfer mented state in wines, and to other similar purposes. As, however, the process is one of extreme delicacy, this method must be used with great caution.
manufacture of sugar from the sugar-cane and other sources is now one of the largest branches of human industry, but this great development is of comparatively recent date; and although there are evidences of its very high antiquity in India and China, sugar appears only to have been vaguely known to the Greeks and Romans. It is mentioned by Theophrastus as "honey in reeds; " and Lucan has the fol lowing line, which indicates a knowledge of its existence, but merely as a curious fact: Quique bibunt tenera dulces ab arundine succos.