COLORING.
The most satisfactory color that can be given copper is a bronze which comes naturally if left to come in contact with varying atmospheres. If the object has a good polished surface in the first place the color seems to become richer as time goes on.
A color that is satisfactory in many cases is obtained in the following way:
Place in a porcelain dish and bring to a boiling heat, liver of sulphur, 1 oz., and water, 1 qt. Dip the object to be colored in this solution while hot and then rinse in clean water. This gives the object a very dark color. Take a little powdered pumice stone on a piece of cloth and rub over the surface lightly bringing the copper color to the surface where desired.
A greenish color is given copper by submitting the object to the fumes of spirits of ammonia.
Beautiful colors are obtained by heating the object to different degrees, over a gas plate, but these results are not permanent.