Etching is the only kind of engraving which can conveniently be done directly from nature. The choice of subjects is the most important point, as, although etching is admirably adapted for trees and vegetation in all its forms, and for picturesque buildings and animals, it is not so well suited for the representation of figures, or for other subjects which require deli- ' cate gradations of tones. For anything that can be expressed by lines, etching is very successful, but it is not easy of application to tones. In working from nature, the shading, in addition to giving the light and dark tints, should also be used to indicate the form and texture of the surface, the lines being drawn in a direction to indicate form as well as tint. Several plates, ready grounded, may be carried in a small grooved box to keep them apart; if only one plate is intended to be used, it can be carried between two light boards, but must not be allowed to touch them. This can be avoided by fixing small pieces of modelling wax at the corners of the plate. If intended to be etched on Hamerton's positive process, the drawing board, with the well in it, must be taken, and the necessary hydrochloric acid and chlorate of potash in two stoppered bottles. These can be mixed with water when required.
Dry point is frequently used in the finishing of etched plates. The dry point is an ordinary steel etching needle, sharpened in a peculiar manner with a sharp rounded cutting edge, and used without either etching ground or acid bath. By using this tool on the bare copper, a burr is raised, which catches the ink, and in printing gives the desired effect of a line with a delicate gradation. The more perpendicular the needle is held the less burr there will be raised; by inclining the hand to the right the burr will be increased, if the pressure on the tool remaius the same. Practice enables an etcher to regulate the pressure on the tool; but if the pressure used has raised too strong a burr, it can be partially or entirely removed by using a sharp scraper worked at right angles to the line. If it is desired to see the progress of the work, rub a mixture of tallow and lampblack over the plate; remove what is superfluous with a soft rag; the effect of the etching can then be fairly judged of. Dry point etching can now be made to give a large number of impressions, by having the plate protected with a coating of steel applied by galvanism.
To efface faulty work, use sand-papers of several degrees of coarseness; the coarsest first, then the scraper; finally, rub over with willow charcoal and olive oil. This leaves the plate fit to be etched upon; if, however, it should be hollowed out by this process, mark the spot on the back of the plate by means of callipers. Lay the face of the plate on a block of polished steel, and give it two or three blows on the back with a rounded hammer. The engravers' copper planers will do this work with more precision and skill than can easily be acquired by ordinary etchers. A passage that has been over-bitten may be easily reduced by being rubbed with willow charcoal and olive oil, which merely reduces the copper without injuring the lines, except the very pale ones; these must be etched over again. It is better to have the plate over-bitten than not enough, as the former is more easily remedied than the latter.
Stippling is also executed on the etching ground by dots instead of lines made with the etching needle, which, according to the intensity of the shadow to be represented, are made thicker and closer. The work is then bit-in.
Etching on Steel is executed much in any other country, it is known under the more common names of chipped or crystalline glass, and the operation of manufacture "glass chipping." It has a remarkable appearance, being covered with fern-like figures, no two of which exactly resemble each other, differing in both shape and form. To those unacquainted with the method of producing this glass - and there are very few that have any conception of how it is made - the process of manufacturing is very puzzling.