(From the Syriac term mana, a gift; as it is supposed to be the food bestowed by God on the children of Israel). Manna Calabrina, ros Calabrinus, aeromeli, alusar, drosomeli; and when of a rosy colour, nuba.
The miraculous food bestowed on the children of Israel is said to have been more probably sugar than manna, as it exuded on the reeds and grass; but it fell also on the stones, and was mouldy and fetid if kept beyond the day, except that day was the sabbath. It could therefore be neither, but a miraculous substance, of which we can form no idea.
The officinal manna has been supposed to be an exudation from the fraxinus ornus Lin. Sp. Pl. 1510; but on this subject authors speak with indecision and doubt. In fact it is produced from the fraxinus with the rounded leaf: the leaf of the f. ornus is smaller and pointed. Later naturalists have called these species the f. rotundifolia; and a full description of the tree is given in the Memoirs of the Society of Agriculture at Paris (an. 1788, trimestre dhyver) by Gaspard Carramone, who has examined it on the spot. We shall only transcribe from this memoir the distinction between the true species and the common ash.
The common ash is found in flat marshy places, particularly near the sea: the ornus, by which he means the round leaved ash, on the clifts of mountains. The surface of the bark of the former has not the white spots so conspicuous on that of the hitter. The leaves of both are decompounded, but the last foliole of the common ash is always larger than the lateral folioles, which is not the case with the true manna tree. In the latter the leaf is unbroken and oval; in the former dentelated, and a long ellipsis.
The Calabrians distinguish different sorts of manna; the manna di spontana, which exudes spontaneously; m. forzatella, that which is procured by incision; m. di fronde, which exudes from the leaf; m. di corpo, which proceeds from the body of the tree. Manna flows spontaneously from the 20th of June to the end of July, from twelve at noon to the evening, in the form of a clear fluid. It is collected on the following morning if the night is fair, for otherwise it is washed off by the rain. This, when hard, is the picked manna, or the sorted manna of the shops. About the end of July, when the spontaneous exudation has ceased, incisions are made in the body of the tree, when more copious exudations take place, which fall to the ground like masses of wax. This, when dry, becomes reddish or brown, and is full of impurities.
What is collected from the leaves is styled grain manna, in little masses, about the size of a millet seed, and is found in the months of July and August. The Calabrians sometimes introduce a straw into the incisions, and the manna flows through and around it like stalactites, sometimes in very large pieces. This is very white and pure, called manna in tears. Many other species of the ash afford manna, and it has lately been found in asparagus, by M. Robiquet, Annales dchimie, vol. 55.
Manna resembles sugar in taste, but greatly differs from it in many other respects. Its sweetness is in a very small degree owing to its truly saccharine particles; for it admits only of a partial fermentation, and the product, though slightly vinous, never resembles alcohol (Dupuy-tren et Thenard, Annales de Chimie, Juillet, 1806). Ardent spirit dissolves a large portion of manna, which is almost wholly deposited in cooling, so as to fill the vessel with the precipitate, and with nitric acid, a large proportion of mucous acid is produced. It is chiefly, therefore, a mucous substance; and these experiments explain why, even in large doses, it does not produce heartburn, or prove in any degree inconvenient during pregnancy.
The finer manna of commerce is in oblong, roundish, single pieces; or in stalks, moderately dry, friable, of a whitish or pale yellowish colour, light, and somewhat transparent; internally it is seemingly composed of fine capillary crystals. The inferior kinds are moist, unctuous, brown, mixed with small pieces of wood and other impurities, and in irregular lumps; the manna di corpo before described.
The whitest, driest, lightest, purest, the most crystalline, and that slightly pungent to the taste, is preferred. The manna in flakes is supposed to be the best, but the smaller pieces are as good, if white, or of a pale yellow colour, very light, of a sweet not unpleasing taste, and free from impurities. The fat honey like manna hath either been exposed to moist air, or is damaged by sea water, or a mixture of oily substances.
Manna is often adulterated by compositions of coarse sugar, starch, and some purgative medicine, as scam-mony; but the fraud is discovered by the taste, weight, compactness, want of transparency, and its chemical affinities.
This concreted juice liquefies in a moist air, dissolves readily in water, and, by the help of heat, in rectified spirit, leaving only the impurities. A great part of the saturated spirituous solution separates on cooling, concreting into a flaky mass, of a snowy whiteness, and a very grateful sweetness: the remaining fluid, when inspissated, is unctuous, dark coloured, and disagreeable.
Manna is one of the mildest purgatives, and may be given with great safety to children and pregnant women, to the delicacy of whose frames and situation it is particularly adapted; it is an useful auxiliary to the purgative neutral salts, sheathes acrimony, is beneficial in coughs and disorders of the breast, particularly such as are attended with fever and inflammation, and in bilious complaints; but is apt to create flatulencies and cholics, which are prevented by a warm carminative. It purges in doses of from i. to ij. and this quality is increased by a small addition of cassia. When administered in bilious disorders, Geoffroy recommends quickening it with a small proportion of antimonium tartarizatum, to evacuate the bilious serum without nauseaor colic. Sydenham recommends the addition of lemon juice to manna, as a remedy for the gravel, and adds, that the acid renders the manna a quicker purgative, diminishing at the same time the nausea which it sometimes excites, renders it easy on the stomach. In bilious complaints tamarinds are usefully joined with manna. In the gravel, the hooping cough, and when all possible irritation -should be avoided, the manna may be given in milk. Modern practice does not very often employ this medicine alone, for the dose is so large as to cloy the stomach, and produce nausea. See Raii Historia; Tourne-fort's and Lewis's Mat. Med.; Neumann's Chemistry.
Manna thuris. See Olibanum.
Manna tereniabin, and trangebin. See Al-hagi.