Lastly, Kühnemann (1875) extracted from barley a crystallized dextrogyrate sugar, and (1876) an amorphous lævogyrate mucilaginous substance Sinistrin ([see p. 692]); according to that chemist, dextrin is altogether wanting in barley.
Barley when malted loses 7 per cent.; it then contains 10 to 12 per cent. of sugar, produced at the expense of the starch; before malting, no sugar is to be found.
Uses—Barley as a medicine is unimportant. A decoction is sometimes prescribed as a demulcent or as a diluent of active remedies. An aqueous extract of malt has been employed.
OLEUM ANDROPOGONIS.
Oleum Graminis Indici; Indian Grass Oil.
Botanical Origin—Among the numerous species of Andropogon[2703] which have foliage abounding in essential oil, the following furnish the fragrant Grass Oils of commerce:—
1. Andropogon Nardus L.,[2704]—a noble-looking plant, rising when in flower to a height of 6 or more feet, extensively cultivated in Ceylon and Singapore for the production of Citronella Oil.
2. A. citratus D.C.,[2705] Lemon Grass,—a large coarse glaucous grass, known only in a cultivated state, and very rarely producing flowers. It is grown in Ceylon and Singapore for the sake of its essential oil, which is called Lemon Grass Oil, Oil of Verbena or Indian Melissa Oil; it is also commonly met with in gardens throughout India and is not unfrequent in English hothouses. In Java it is called Sireh.
3. A. Schœnanthus L.,[2706] a grass of Northern and Central India, having leaves rounded or slightly cordate at the base, yielding by distillation the oil known as Rúsa Oil, Oil of Ginger Grass or of Geranium.
History—The aromatic properties of certain species of Andropogon were well known to Rheede, Rumphius, and other early writers on Indian natural history; and an oil distilled from the Sireh grass in Amboyna was known as a curiosity as early as 1717.[2707]