I first take metallic sheets, preferring for the purpose iron, as this metal is the only one, except the precious metals, which is without action on the silver salts generally used, as also the other chemicals; but other metallic or mineral sheets may be used, and I do not, therefore, confine myself specially to any particular metal. Upon each of the sheets is prepared a black japanned or varnished surface, such as is used by tinners or japanners for coating metallic and other surfaces. The japan or varnish may be made and applied as follows:--Take one quart of raw linseed oil; add to this two ounces of asphaltum and sufficient umber, or lamp black, to give the desired shade. Boil these ingredients until a portion dropped on a cool surface will remain in a round spot without flowing away. It is then thick enough to use. If it should be too thick, it can readily be thinned with spirits of turpentine. Apply the japan to the sheets or plates with a brush, and after allowing it to stand a short time, until the marks of the brush disappear, place the sheets or plates in a drying oven and submit them to heat until the surface will bear the finger to be drawn over it without bringing off the japan; it may, if found necessary, be coated again and treated in a similar way, and finally polished with rotten-stone and oil, or other polishing material. Other ingredients may be used in making the japan, such as mastic, lac or copal varnish, and other shades of coloring matter may be used. By collodion I mean any solution of gun-cotton or pyroxyline; and by a solution of salt of silver, I mean any of the salts thereof which can be used in photography for obtaining positive impressions by a camera. A japanned surface may be prepared on glass, or on leather and other fibrous materials. Or glass may be made black by means of coloring matter introduced or embodied with the glass, so as to be _in_ instead of _on_ the glass. But foreseeing the difficulty of embracing all these applications in one application, I do not desire to have them so considered; but reserve the right to hereafter apply for such application of my general principle as I may deem essential, or of sufficient importance to be protected by Letters Patent. And it might be proper to add, that vulcanized gutta-percha or indurated rubber may be used as the basis upon which, or in which the japanned surface may be made. The invention, however, consists mainly on the surface, so that a silver picture may be made upon it, said surface forming the background of the picture. The ingredients for fixing and developing the positive impression, upon the japanned surface may be the same as those heretofore essayed by me in a former application, and need not again be repeated here. Though other chemicals, or other proportions of the same chemicals, may be used.