The aloe is a plant of the Monogynia order, belonging to the Hexandria class. The medical substance called aloes, is the inspissated juice of the plant. There are three sorts of this, viz. socotrina, hepatica, and cabal-lina. The first of these, which is considered the best, comes from the island Socotora, whence its name. It is of a glossy appearance, and in a slight degree pellucid; if reduced to powder, it is of a bright golden colour. The hepatica is so called from its liver colour, and is chiefly brought from Barbadoes in large gourd shells. Its taste is intensely bitter and nauseous. The caballina is principally used as a medicine for horses, from which circumstance it derives this appellation. It is coarser and more impure than the others, and has a rank strong smell. The three varieties have, however, all been obtained from the same plant, at Morviedro, in Spain. The first, from the liquid which flows spontaneously from the incised leaf; the second, from the juice afterwards extracted by pressure; and the third, by mixing the expressed juice with the dregs of the former.

Pure aloes are nearly soluble in water and in alcohol.

They are powerfully aperient, and in large doses produce much irritation; small doses are tonic and aperient.