the process of engraving metal plates by means of an acid. The plate is cleaned and covered with an etching ground, which is a composition of Egyptian asphaltum, virgin wax and Burgundian pitch. This protects the surface from the action of the acid. The design is then cut through this coating with steel tools, called etching needles, and the plate is placed in a weak solution of nitric acid. The acid eats on "bites," the design in the plate. The different degrees of light and shade are produced by etching some portions of the plate more than others. After the lines which require but little etching have been formed, that portion of the plate is again covered with etching ground and the action of the acid on it stopped. Some of the finest works are reproduced by combining etching and engraving in the preparation of the plates. See ENGRAVING; ZINC ETCHING.