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Ash, Manna | | Name : | Ash, Manna | | Botanical : | Fraxinus ornus | | Synonyms : | Flake Manna. | | Family : | Oleaceae | | Parts Used : | Concrete exudation. | | Description : | A foreign species of Ash (Fraxinus ornus, Linn.), the South European Flowering Ash, a small tree indigenous to the coasts of the Mediterranean from Spain to Smyrna, yields from its bark a sugary sap called Manna, used in pharmacy.
The tree blossoms early in summer, producing numerous clusters of whitish flowers; in this country it only attains a height of 15 or 16 feet.
To-day, the Manna of commerce is collected exclusively in Sicily, from cultivated trees, exported from Palermo. The trees are grown in plantations placed about 7 feet apart. When from eight to ten years old, when the trunk is at least 3 inches in diameter, the collection of Manna is begun. In July and August, when the trees have ceased to put forth leaves freely, a vertical series of oblique incisions are made in the bark on alternate sides of the trunk. Dry, warm weather is essential for a good crop of the Manna which exudes. The larger pieces of incrustation that form, and which are collected in September and October, when the heat has begun to moderate, are known as Flake Manna, and this is the best. It is put on the market in long pieces or granulated fragments of a whitish and pale yellow colour, irregular on one side and smoother and curved on the other, rarely more than 1 inch broad and 2 to 3 inches or more long.
The pieces adhering to the stem after the finer pieces have been gathered are scraped off and form part of the small Manna of commerce. The pieces that form on the lowest incisions, or the pieces that are collected on tiles placed under the tree, and known as 'gerace,' are less crystalline, more glutinous, and are in moist adhesive masses of a dark brown colour. These are less esteemed. | | Constituents : | Manna of the best quality dissolves in about 6 parts of water, forming a clear liquid. It has no bitterness or acridity.
The chief constituent of Manna is a peculiar, crystallizable, sweet principle called Mannite or Manna Sugar, present to the extent of about 70 per cent. It also contains a fluorescent body named Fraxin, which occasionally gives a greenish colour to Manna and on which is thought to depend its purgative property. Some true sugar and a small quantity of mucilage are also present.
Mannite is white, inodorous, crystallizable in semi-transparent needles of a sweetish taste, soluble in 5 parts of cold water, scarcely soluble in cold alcohol, but readily dissolved by alcohol when hot and deposited when cool. Unlike sugar, it is incapable of undergoing vinous fermentation. | | Uses : | Manna has a peculiar odour and a sweetish taste.
It was formerly used in medicine as a gentle laxative, but is now chiefly used as a children's laxative or to disguise other medicines.
It is a nutritive and a gentle tonic, usually operating mildly, but in some cases produces flatulence and pain.
It is still largely consumed in South America and is official in the United States Pharmacopoeia.
It is generally given dissolved in water or some aromatic infusion, but the best Flake Manna may be administered in substance, in doses of a teaspoonful up to 1 or 2 oz.
Usually it is prescribed with other purgatives, particularly senna, rhubarb, magnesia and the neutral salts, the taste of which it conceals while it adds to the purgative effect.
For infants, a piece about the size of a hazel-nut is dissolved in a little warm water and added to the food. To children, 30 to 60 grams may be given dissolved in warm milk or a mixture prepared with syrup, or syrup of senna and dill water.
Syrups of Manna are prepared with or without other purgatives.
Manna is sometimes used as a pill excipient, especially for calomel.
Under the name of Dulcinol, a mixture of Manna and common salt has been recommended by Steinberg in 1906 as a sweetening agent in diabetes, the dose 1/2 to 1 OZ.
The Codex of the British Pharmacopceia contains a Syrup of Manna to be prescribed as a mild laxative for children, in the proportion of 1 part of Manna to 10 of water.
The Compound Syrup of Manna of the B.P. Codex is stronger than the Syrup of Manna and contains Senna and fennel in addition, the dose being 1 to 4 fluid drachms. |
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