One of the constituent acids of oil obtained by the action of superheated steam.

Characters.-A yellowish oily liquid, odourless, tasteless, neutral in reaction. Sp. gr., .800 to .810. Insoluble in water ; soluble in alcohol, chloroform, benzol, benzin, turpentine, and fixed oils. It dissolves most metallic oxides, forming indefinite solutions of oleates in excess of oleic acid.

Non-officinal Preparations of Oleic Acid. Oleate of Mercury; Oleate of Lead; Oleate of Zinc ; and various ointments and plasters.

Action And Uses

Oleic acid is much more readily absorbed by the skin than the fixed oils from which it is derived, and preparations made with it as the solvent or basis have a high penetrating power. The oleate of mercury is now extensively employed.

Manna-Manna.-A concrete saccharine exudation from the stem of Fraxinus Ornus. and F. rotundifolia. Obtained by making incisions in the stems of the trees, which are cultivated for the purpose, chiefly in Calabria and Sicily.

Characters.-In stalactiform pieces from one to six inches in length, and one or two inches in width, uneven, porous, and friable, curved on one side, of a yellowish-white colour, with a faintly nauseous odour, and a sweetish taste.

Composition.-Manna consists principally of about 70 per cent. of mannite, C3H703, common sugar, and extractive matter. Mannite does not undergo vinous fermentation.

Dose.-60 gr. to 1 oz.

Action And Uses

Manna is a mild laxative, commonly given to children for constipation, because not unpleasant and easily dissolved in milk.