1318. Phosphate of lime is a combination of phosphoric acid and lime, one proportion of each. It is a compound insoluble in pure water, but soluble in water containing any acid matter. It forms the greater part of calcined bones. It exists in most excrementitious substances, and is found both in the straw and grain of wheat, barley, oats, and rye, and likewise in beans, peas, and tares, and in the ashes of most kinds of wood. It exists in some places in these islands native, but only in very small quantities. Phosphate of lime is generally conveyed to the land in the form of bones, but it also enters into the composition of all other organic manures.