To give iron a dead black color, clean all grease and dirt from the metal, and apply the following solution either with a brush or by dipping. Mix together thoroughly 1 part bismuth chloride, 2 parts mercuric bichloride, 1 part copper chloride, 6 parts hydrochloric acid, 5 parts alcohol and 52 parts water. As soon as these parts are thoroughly mixed, the compound is ready for use. After applying the compound, the iron is placed in boiling water and allowed to remain for one-half hour, the water being kept at the same temperature. Repeat this operation until the color is deep enough, then fix the color by placing the iron for a short time in a bath of boiling oil. After removing, heat in an oven until the surplus oil is all driven off. Urbana, Ill. T. E. O'Donnell.
A fine black coat is produced on steel if treated in the following manner: An oxidized skin is first produced in some suitable manner on the surface of the steel; this is converted into black oxide by means of hot water and continued until the coat of oxide is thick enough. Then the articles are dipped in lukewarm water to remove any acid or salty particles, and then some olive oil is poured over the whole. D.
The pieces to be blackened should first be polished with No. 120 emery cloth. After polishing, the surfaces should be cleaned carefully, and then the work placed over the fire and drawn evenly to a second blue. Then, the work is dipped in lard or sperm oil, from which it is immediately removed, and all loose oil shaken off. This prevents the forming of blisters. An old piece of rubber, for instance a piece of old garden hose, is then placed on the fire, and as it bums, the work is held over the flame and smoke that comes from the rubber, until it is covered with a thick coat of black soot. The work is then removed from the fire, and permitted to cool off slowly. When cool, it is rubbed with an oiled cloth. All this must be done in one heat.
Tarrytown, N. Y. E. W. Norton.
Heat the article to a low heat and dip into a solution of nitrate of copper, made by dissolving copper in nitric acid. Then heat the piece dipped over a spirit lamp or Bunsen burner until from greenish color it finally turns black. H. A. Sherwood.
The scale is varnished over with a little thin shellac varnish, so as to sink into all the cuts. When this is dry, a black varnish of lampblack and shellac is spread on, so as to fill all the cuts. This is allowed to thoroughly dry. When hard, the work is driven in the lathe, and the superfluous varnish polished off with fine flour emery cloth until only that in the cuts is left. This gives a very distinct marking and fine finish to scale. F. H. Jackson.
Angelica. N. Y.