This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
Beautiful colorations, resistive to light, may be given to metals by the following method:
The metallic objects are immersed in a colorless varnish with pyroxyline, and dried in a current of hot air at 176° F. When the varnish is sufficiently dry, the objects are bathed for a few minutes in a 2 per cent alcoholic solution of alizarine or of a color of the same group. By washing with water the yellowish color covering the object on coming from the coloring bath passes to the golden red.
To redden copper hang it from a few minutes to an hour, according to the shade wanted, in a 5 to 10 per cent solution of ferrocyanide of potassium in water. By adding a little hydrochloric acid to the solution the color given to the copper may be made to assume a purple shade. On removing the copper, dry it in the air or in fine sawdust, rinse, and polish with a brush or chamois leather, after drying it again.
To blue copper or brass any one of the following recipes may be used:
Dip the article in a solution of 2 ounces of liver of sulphur and 2 ounces of chlorate soda in 1,000 ounces of water.
Dip the article in a solution of ferrocyanide of potassium very strongly acidulated with hydrochloric acid.
Stir the article about constantly in a solution of liver of sulphur in 50 times its weight of water.
The point of fusion of common metals is as follows: Antimony, 808° F.; aluminum, 1,160° F.; bismuth, 517° F.; copper, 1,931°F.; gold, 1,913° F.; iron, 2,912° F.; lead, 850° F.; nickel, 2,642° F.; platinum, 3,225° F.; silver, 1,750°F.; tin, 551°F.; zinc, 812°F. Mercury, which is normally fluid, congeals at 38° below zero, F., this being its point of fusion.