Of course all the rough parts must be smoothed up with a file; then use emery paper or emery cloth to rub out the file marks and finally finish off the surface by polishing it with crocus 23 put on with a cloth.

Coloring Metals

Many things that you make of metal can be greatly improved in appearance by coloring them.

22 Machine screws and bolts for model work can be bought of Luther H. Wightman, Boston, Mass.

23 Crocus is a powder made of iron rust.

Bluing Steel

First polish the articles and clean them by immersing them in a hot solution of caustic soda. Now put the screws, or whatever it is you want to blue, in an iron pan half full of dry, clean sand and heat them over a fire.

Keep moving the articles around with a pair of tweezers until they are the color you want them and then drop them into clean oil.

Bluing Brass

Polished pieces of brass can be given a fine color by putting them in a solution made as follows:

Stir 1 1/2 drams of antimony sulphide,24 2 ounces of calcined soda in 3/4 of a pint of water; to this solution add 2 1/4 drams of kermes. Stir well, filter it and then mix it with 2 1/4 drams of tartar, 5 1/2 drams of hyposulphite of soda dissolved in 3/4 pint of water when it is ready to use.

Giving Brass a Green Color

Make a solution of 2 ounces of copper sulphate, 1/2 an ounce of sal ammoniac and 25 ounces of water. Suspend the articles to be greened in the solution and boil it until you get the color you want.

Giving Brass a Dull Look

First clean the articles thoroughly; then mix 1/4 ounce of iron rust and 1/4 ounce of white arsenic in 4 ounces of muriatic acid. Use a brush and paint the articles with this solution until it takes on the proper dull appearance. Then wipe it off, oil, dry and lacquer it.

24 This and all other chemicals can be bought of Eimer and Amend, Fourth Ave. and 18th Street, New York.

Frosting Brass Articles

Hang the brass articles in a boiling solution of caustic potash, wash them off in clean water and dip them in nitric acid until the oxide is gone, wash them again and throw them in sawdust to dry; heat them a little and lacquer while they are warm.