Compiled by Ivor Hughes

Manna is the dried exudation of Fraxinus Ornus Linne (Tarn. Oleaceae). Manna yields not less than 75 per cent, of anhydrous alcohol-soluble extractive, using 90 per cent, alcohol." U. S.
Manne, Fr. Cod.; Manna, P. G., It.; Mana, Sp.

The term "manna" is applied to saccharine exudates from various trees. The official variety occurs on the manna ash, Fraxinus Ornus The term " manna" has also been applied to certain substances which have no relation to true manna, notably to the lichen, Lecanora esculenta, which at times has suddenly fallen like rain over immense tracts of country, from Persia to the African Sahara.

It occurs in the form of small roundish lumps, from the size of a pin's head to that of a pea, yellowish or grayish externally and whitish within, hard, inodorous, and insipid. It has been affirmed that this lichen does not contain starch, but it is really used as an article of food, and good bread is said to have been made out of it. (Nature, Jan., 1891.) It is probable that it is the manna of Scripture. In the Chemist & Druggist, xcii, p. 750, E. M. Holmes interestingly discusses the source of Biblical manna and expresses the belief that it was a fungus similar to that found in Central Africa in the district of Tanganyika.

Fraxinus Ornus, or the European flowering ash, is a tree of moderate height, usually from twenty to twenty-five feet, with opposite, petiolate, pinnate leaves, composed of three or four pairs of leaflets, and an odd one at the end. The leaflets are oval, acuminate, obtusely serrate, about an inch and a half in length, smooth, and of a bright green color. The flowers are white, and usually expand with the leaves. They grow in close panicles at the extremities of the young branches, and have a very short calyx with four teeth, and four linear-lanceolate petals. The manna ash is a native of Southern Europe and is largely cultivated in Italy and Sicily. It yields manna after the eighth year, and continues to yield it for ten or twelve years, when it is usually cut down and young sprouts are allowed to grow up from the root. (Stettner, A. Pharm., liii, 194.) During the hot months the juice exudes spontaneously from the bark, and concretes upon its surface, but, as the exudation is slow, it is customary to facilitate the process by making deep longitudinal incisions on one side of the trunk. In the following season these are repeated on the other side, and thus alternately for the whole period during which the tree yields manna. Straw or chips are frequently placed so as to receive the juice, which concretes upon them. The manna varies in its character according to the mode of collection, the nature of the season, and the period of the year at which the exudation takes place. For information on manna collection in Sicily, see notes by J. S. Ward. (P. J., 1893, 381.) Ebert (Zeit. Oest. Apoth. Ver., xlvi, p. 427) has contributed a very able paper, containing citations of all the literature up to 1908, regarding the origin and pharmaeognosy of the different varieties of manna. Probably the most comprehensive monograph on the ash manna is that of Tschirch in his large work entitled " Handbuch der Pharmakognosie" Band II, p. 103. In commerce the following varieties are distinguishable :

1. FLAKE MANNA, or Manna canulata (cannel-lata), is the purest variety, and is chiefly obtained from Palermo. It exudes spontaneously, or from incisions, during the hottest and driest weather in July and August. According to Stettner, it is furnished by the upper incisions upon the trunk, while the lower incisions yield the inferior varieties. It is in irregular, elongated, flattened, 3-sided pieces, often several inches long, resembling stalactites, rough, light, porous, brittle, whitish or yellowish-white, and frequently concave on the surface by which they were attached to the trunk, and which is often soiled by impurities, sometimes by adherent fragments of the bark. The entire pieces vary from 10 to 25 cm. in length and constitute the " long flake manna" of commerce. When broken, these pieces exhibit a crystalline or granular structure. This variety is sometimes in small pieces, generally less than an inch in length, when it is called " small flake manna."

2. MANNA IN SORTS, Manna communis, is next in quality, and is collected in Italy and Sicily in September and the beginning of October, when the heat of the weather has begun to moderate. The juice does not now concrete so readily, and a portion, falling on the ground at the root of the tree, becomes more or less mixed with impurities, and forms imperfectly solid masses, which require to be further dried in the sun. Manna in sorts consists of whitish or yellowish fragments, similar to the pieces of flake manna, but much smaller, mixed with a soft, viscid, uncrystallized brownish matter.

Most of the world's supply of manna is yielded by five Italian provinces. Flake manna is produced in Capaci, Geraci and Frassino, these yielding in order 62.15 per cent., 62 per cent., and 47 per cent, of mannite. Manna in sorts is produced in Capaci, Geraci and Castelbuono, yielding respectively 37 to 55 per cent., 37 per cent., and 28 to 30 per cent, of mannite. Manna is shipped to the United States in cases from Palermo, Italy, only the large and small flake varieties being imported at present. The chief past adulterants for manna have been glucose, sucrose and bread crumbs.

Fictitious Manna.� Attempts have been made to counterfeit manna, but the facility of detection renders such frauds unprofitable, and they are not often practised. R. P. Thomas described (A. J. P., xxiv) a sophisticated manna which differed from the genuine drug both in sensible and in chemical properties, not even containing mannite. Baume describes a method in which common manna is purified so as to resemble flake manna. It consists in dissolving common manna in a little water, allowing the liquid to settle, decanting it in order to separate the impurities, then inspissating it so that it will congeal on cooling, and immersing threads in the inspissated liquid, several times successively, in the manner practised by candle makers. It may be still further purified by the use of animal charcoal. Thus prepared, it contains less mannite than flake manna, and less of the nauseous principle, but is said not to operate less effectively as a laxative.

Description and Physical Properties.� In irregular, more or less elongated, flattened, 3-sided pieces; externally yellowish-white; friable; internally nearly white, porous and crystalline in appearance; odor slight; but characteristic ; taste sweet, slightly bitter and faintly acrid. Also in irregular masses, consisting in part of brittle or soft fragments from yellowish-white to yellowish-gray in color. The quantity of these yellowish-white fragments must not be less than 40 per cent, of the whole.

Assay.� Proceed as directed under alcohol-soluble extractive, using boiling 90 per cent, alcohol, by volume, and filter rapidly through purified cotton while hot, washing the cotton with boiling alcohol. U. S.

Manna has a slight, peculiar odor, and a sweet taste, which in the impure kinds is also very nauseous, but in the finest flake manna scarcely so much so as to be disagreeable. Its sp. gr. is 0.834. It melts with heat, and takes fire, burning with a blue flame. When pure it is soluble in three parts of cold and in its own weight of boiling water. From a boiling saturated aqueous solution it separates in partially crystalline masses on cooling1. Alcohol also dissolves it. Boiling alcohol will dissolve 15 parts of manna, and upon cooling deposit beautiful crystals of mannite.

Constituents.� Manna is variable in its constituents. The principal constituent, mannite, ranges from 30 to 90 per cent., the lower percentage being in the poorer varieties and the higher percentage in the better varieties of this drug. Sucrose and invert sugar ranges in amounts from 2 per cent, to 30 per cent., the higher amounts being in the lower grades of manna. There is also present gum, dextrin and traces of citric acid, and fraxin. Tanret, after an exhaustive investigation of manna, reported the following carbohydrates as having been identified by him: Mannite, dextrose, levulose, mannotetrose, and mannotriose. The manna which occurs in tears and distinct fragments is much higher in mannitol than other grades.

The greenish color of certain pieces of manna is produced by fraxin, C16H18O10, a glucoside closely resembling aesculin. Fraxin crystallizes in colorless prisms, easily soluble in hot water and in alcohol, and has a faintly astringent and bitter taste. By diluted acids it is resolved into fraxetin, C10H8O5, and glucose, C6H1806. Even its diluted solutions are fluorescent.

Mannite (mannitol or hexanhexol) is white, inodorous, crystallizable in semi-transparent needles, of a sweetish taste, soluble in five parts of cold water, scarcely soluble in cold alcohol, but readily dissolved by that liquid when hot, and deposited when it cools. Its composition is C6H14O6, and it is considered as belonging to the class of hexatomic alcohols. It was discovered by Proust in manna in 1806. With lime, barium and strontium oxides, it forms definite compounds, soluble in water, and precipitable from their aqueous solutions by alcohol. It does not reduce an alkaline solution of copper oxide; and a test of its purity is thus presented. Emil Fisher has shown that there are three mannites obtainable; the ordinary mannite is the dextrorotatory variety, and is always obtained in the reduction of a-mannose with sodium amalgam; a laevorotatory variety is obtained by the reduction of l-mannose; and an inactive mannite is obtained from the inactive mannose. These three physical isomers differ slightly in their fusing points and crystalline form. The native variety may be obtained by boiling manna in alcohol, allowing the solution to cool, and redissolving the crystalline precipitate; pure mannite is now deposited.

Another method is to dissolve flake manna in water, precipitate by solution of lead subacetate, filter, throw down the excess of lead by sulphuric acid, evaporate the solution, and mix with alcohol. On cooling, the mannite is deposited. (Bonsall, A. Pharm., cxxxiv, 70.) Mannitol occurs in the larch, celery and sugar cane in small amounts. Agaricus integer contains 20 per cent, of mannitol. When heated mannitol yields two anhydrides, mannitan, C6H12O5, and mannide, C6H10O4. There are four stereo-isomerides known. They are dulcitol, sorbitol, talitol and iditol. Dulcitol occurs in a number of plants naturally, the others are synthetic products. Mannitol hexanitrate is described under Nitrated Alcohols, Part II. It is said to be gently laxative in the dose of from one to two ounces (31-62 Gm.).

Manna, when long kept, acquires a deeper color, softens, and ultimately deliquesces into a liquid, which on the addition of yeast undergoes the vinous fermentation. This is probably owing to its conversion into sugar by the absorption of enough oxygen to cause it to pass over into some variety of glucose or fermentable sugar. That which is driest resists this change the longest. It is said that manna recently gathered is less purgative than it afterwards becomes.

A number of exudates from other sorts of trees have from time to time appeared in the markets under the name of manna; these false mannas are to-day of no commercial importance but the following are those which in the past have had more or less prominence; for further information concerning these see U. S. D., 20th ed., p. 685

.European False Manna, or Briangon Manna, an exudation from the common European larch (Larix europaea, or Pinus Larix), differs chemically from ordinary manna in containing no mannite. Berthelot (1859) found in it a sugar, melezitose.

California Manna, or Father Picolo's Manna. � Proust (1806) alluded to a manna mentioned by Father Picolo as being deposited on a species of grass in California. J. TJ. Lloyd (A. J. P., 1897, 337) believes Picolo's manna to be a saccharine deposit, caused by aphides on Phragmites communis. It is apparently still collected by the Indians.

Turkish Manna is a sweet product obtained from Echinops persica Fisch., and is obtained by treating the cocoons of a coleopterous insect (Larinus maculatus) with hot water, filtering and crystallizing the sugar. From it Berthelot (1857) obtained sugar, trehalose. Pinus Cedrus, of Mount Lebanon, yields a similar product, which has some repute in Syria as a remedy in phthisis. (P. J., xiii, 411.) In the neighborhood of Diarbekir, in Asiatic Turkey, a saccharine substance, known as Diarbekir Manna, is found on the leaves of dwarf oaks, from which it appears to be exuded. Quercus Valonea Kotschy, and Q. persica Jaub. et Spach, yield " oak manna," through insect agency.

Persian Manna.� Several manna-like exudates are, or were, produced in Persia. Of these, Gez has been identified (C. D., 1894) as being derived from the Astragalus anisicanthus (Fam. Leguminosae). Chirkhest appears to come from the Salix fragilis L. and perhaps other species of willow.

Taranjabiti, or Alhagi Manna, is yielded by the camelthorn, Alhagi Camelorum Fisch., in Persia and Afghanistan, and probably by Alhagi Maurorum Tournefort, a leguminous thorny shrub abundant in India � if indeed the two species be distinct. According to A. Villiers, it is nearly pure melezitose. (P. J., 1876.)

Gazanjabin, or Tamarisk Manna, is yielded by Tamarix gallica var. mannifera Ehrenberg (Fam. Tamariscinae).

Several sweet exudates have been sold in the Indian bazaars. Of these the most important is the Shirkoit, or Oriental Manna. By Haussknecht it is referred to Atraphaxis spinosa; but J. E. T. Atchison states that it is yielded by the Cotoneaster nummularia Fisch. et Mey., a tall, stout shrub, whose smaller branches in July become covered with an exudation. Bamboo Manna, or tab ashir, is obtained from the surface of the stems of the Bambusa stricta Roxb. (Fam. Graminae).

Australian Mannas. � A manna-like exudation on the Eucalyptus viminalis Labill., growing in New South Wales, contains melitose. (See A. J. P., xxviii, 157.) Lerp is produced upon the leaves of Eucalyptus dumosa, when very small, and sometimes appears spread over large extents of country like a kind of snow. Myoporum platycarpum R. Brown, the sandalwood- or dogwood-tree of Australia, exudes an exceedingly sweet and pleasant manna, which is much used as an article of food, the product containing nearly 90 per cent, of mannite. F. W. Passmore obtained from Eucalyptus Gunnii Hook., a sugar termed melitriose. (P. J., 1891, 718.)

Blue Grass Manna is, according to R. T. Baker (Journ. and Proc. Boy. Soc. New South Wales, xxx, 1897), produced in the form of nodules at the nodes of the stems of the blue grass Andropogon annulatus. It contains numerous crystals of mannite, amounting, according to the analysis of H. G. Smith, to 50 per cent.

Uses. � Manna is a gentle laxative, usually operating mildly, but in some cases producing flatulence and pain. It is usually 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. It is usually given dissolved in water or some aromatic infusion; but the best flake manna may be administered in substance. Manna forms a combination with iron, which it preserves against oxidation. (See P. J., March, 1873.) Under the name of dulcinol a mixture of mannite and common salt has been recommended by Sternberg (D. M. W., 1906, p. 1707) as a sweetening agent in diabetes.

Dose, half to one ounce (15.5-31 Gm.).

Off. Prep.� Infusum Sennae Compositum, N. F.; Syrupus Mannae, N. F.

See also the sweetners .. Fraxus ornus L. Martindales 24th in the site library.