Or prepare a solution of sal am moniac, to which add zinc filings or zinc foil until a sediment is formed. Bring this solution to a boil, and im merse the articles until a sufficient coating is formed.
Brazing. — Copper may be coated with brass by boiling the articles in a mixture of argol amalgam, 1 part; zinc, 1 part; muriatic acid, 2 parts, diluted with sufficient water to cover the articles. Copper kettles or other utensils may be coated internally by filling them with this liquid and boil ing them for a time.
Or articles of copper or brass may be given a superficial coating of brass by heating them and exposing them to the fumes of melted zinc. This method is employed to make imi tation gold wire, and also for cheap jewelry, as it gives a higher luster than solid brass.
To Color Brass Gold.— Mix equal parts of muriatic acid and alum with warm water, and steep the articles in the mixture for a few seconds.
To Whiten Brass and Copper.—Mix equal parts of white tartar alum and grain tin. Add water and boil the articles in the mixture. They acquire a coating of tin which will take a high polish like silver.
Or dissolve 4 ounces of chromate of tartar in 1 gallon of boiling water; add 2 ounces of tin salt dissolved in 16 ounces of cold water. Boil, strain, and pour in a thin stream into a ves sel containing 12 ounces of hyposul phite of soda dissolved in 1 quart of water. Bring to a boil and filter.
Articles dipped in this solution take on a series of brilliant metallic lus ters which vary with the time they remain immersed. These range from light yellow to dark gold or reddish brown.
Black Dip for Brass.—Dip the ar ticle in tincture of iron. Let dry and dip in an infusion of tincture of nut galls.
Or carbonate of copper, 1 ounce; aqua ammonia, 5 pounds; water, 10 pounds. Suspend the articles in this mixture, remove, and polish with felt.
Bronzing for Metals.—Bronze when exposed to the air becomes covered with a green coating of a basic cop per carbonate, which protects it from further corrosion. As this coating is much admired, it may be produced artificially in various ways and of different tints and shades as may be desired. _
The solutions for this purpose vary according to the metals to be bronzed and the colors wanted.
To Bronze Zinc. — To 6 pints of muriatic acid add 2 pounds of oxide of iron and 1 pound of yellow arsen ic. Mix well, let stand 48 hours, and shake frequently. It is then fit for use.
Clean the articles perfectly free from grease, dip in this mixture, and jet stand two hours or until black.
Remove and rinse in boiling water. Then apply any good liquid blacking or paste and polish with a brush. Use black lead on the polishing brush to darken the color. Lacquer the ar ticle, and the color will remain for years. All art bronzes are made from zinc and treated in this way.
Or muriatic acid, 1 pint; water, 3 pints; chrome alum, 45 grains. Clean, and dip until colored. Polish with lacquer.
Or, for bronze tints on zinc or iron, dissolve 2 ounces of hyposulphite of soda and 3 ounces of acetate of lead in 3 pints of water. Iron dipped in this becomes blue; zinc becomes cop per colored; brass becomes red, deep blue, or light blue.
Bronzing for Brass. — Vinegar, 5 gallons; blue vitriol, l pounds; muriatic acid, 3 pints; corrosive sub limate, 2 grains; sal ammoniac, 1 pound; alum, 4 ounces. Mix togeth er with gentle heat, dip the articles until the desired tint is secured, rinse in boiling water, and polish with felt and lacquer if desired.
Or warm the article and wash with a hot solution of sal ammoniac. Let stand over night in a solution of 2 ounces of verdigris, 1 ounce of am monium chloride, and 6 ounces of vin egar diluted with water.
Or hyposulphite of soda, 2 ounces; acetate of lead, 3 ounces; water, 3 pints. This gives brass a red, deep blue, or light-blue tint.
To Color Bronze Green. — To 1 quart of strong vinegar add ounce of mineral green, ounce of raw um ber, ounce of sal ammoniac, I ounce of gum arabic, and ounce of cop per. Boil in a little water over a slow fire 2 ounces of French berries and 3 ounces of green oats until their strength is extracted. Add this liquor to the mixture, bring all to a boil, cool, and strain through flannel. Or the oats may be omitted.