Manna is properly a gum, and is honey-like juice concreted into a solid form, seldom so dry but it adheres more or less to the fingers in handling: its colour is whitish, yellowish, or brownish, and it has in taste the sweetness of sugar, and with it a sharpness that renders it very agreeable: we are supplied with manna from Calabria and Sicily, which is the product of two different trees, but which are of the same genus, being both varieties of the ash: when the heats of summer are free from rain, the leaves, the trunks, and branches of both these trees, exsudate a white honey juice, which concretes into what we call manna, forming itself as it runs, and according to its different quantity, into small roundish drops, or long flakes: what flows out of the leaves of these trees is all natural, but the Italians procure a forced kind by wounding the trunks and branches: the finest manna of all is that which oozes naturally out of the leaves in August, after the season of collecting the common manna is over: the French have another sort of manna, produced from the larch tree, of a very different genus of the ash, and the very tree which produces oil of turpentine; this is called Briançon manna, from the country where it is produced: our black thorn, or sloe tree, sometimes yield a true manna from the ribs of the leaves in Autumn, but it is in a very small quantity: there is another sort called the manna Persia, produced from a small prickly shrub about four or five feet high, growing in Egypt, Armenia, Georgia, and Persia. The Hebrews, who had been acquainted with the last mentioned sort of manna, when they found a miraculous food in the desert resembling it, did not scruple to call it manna: this was a conjecture the more natural to them, as they saw plainly that this descended from the heavens in form of a dew, and concreted into the globules in which they found it; and the received opinion at the time was, that the Oriental manna was formed in the same manner; that it was a dew from the clouds concreted on the plant, none supposing, in those early times, that it was the natural juice of the shrub upon which it was found: it is however evident, that this was not of the nature of manna, because it melted away as the sun grew hot, whereas manna hardens in that heaet. It is but lately that the world was convinced of the mistake of manna being an aërial produce, by an experiment being made by covering a tree with sheets in the manna season, and the finding as much manna on it afterwards as on those which were open to the air and dew. Manna is celebrated, both by the ancients and moderns, as a gentle and mild cathartick. Hill.
It would be well inquired, whether manna doth fall but upon certain herbs, or leaves only. Bacon's Nat. Hist.
The manna in heaven will suit every man's palate. Locke.