a name given by the French engineers to a kind of mortar, which they use in raising the foundations of masonry under water. It consists of twelve parts of pozzolans or Dutch tarrafs, six of good sand, nine of unflaked lime, thirteen of stone splinters about the size of an egg, and three of tile-dust or cinders, or scales of iron out of a forge; this being well worked together, is left to stand for about 24 hours, or till it becomes so hard as not to be separated without a pick-axe.