The wood which God showed Moses, that with it he might sweeten the waters of Marah, is called _alvah_, Exod. xv, 25. The word has some relation to aloe; and some interpreters are of opinion that Moses used a bitter sort of wood, that so the power of God might be the more remarkable. Mr. Bruce mentions a town, or large village, by the name of Elvah. It is thickly planted with trees; is the _oasis parva_ of the ancients; and the last inhabited place to the west that is under the jurisdiction of Egypt. He also observes that the Arabs call a shrub or tree, not unlike our hawthorn, either in wood or flower, by the name of elvah. “It was this,” say they, “with which Moses sweetened the waters of Marah; and with this, too, did Kalib Ibn el Walid sweeten those of Elvah, once bitter, and give the place the name of this circumstance.” It may be that God directed Moses to the very wood proper for the purpose. M. Neibuhr, when in these parts, inquired after wood capable of this effect, but could gain no information of any such. It will not, however, from hence follow that Moses really used a bitter wood; but, as Providence usually works by the proper and fit means to accomplish its ends, it seems likely that the wood he made use of was, in some degree at least, corrective of that quality which abounded in the water, and so rendered it potable. This seems to have been the opinion of the author of Ecclesiasticus, xxxviii, 5. That other water, also, requires some correction, and that such a correction is applied to it, appears from the custom in Egypt in respect to that of the Nile, which, though somewhat muddy, is rendered pure and salutary by being put into jars, the inside of which is rubbed with a paste made of bitter almonds. The first discoverers of the Floridas are said to have corrected the stagnant and fetid water they found there, by infusing in it branches of sassafras; and it is understood that the first inducement of the Chinese to the general use of tea, was to correct the water of their ponds and rivers.