For pickling casting to remove the scale prepare a bath in a vessel (lined with lead) of 3 parts muriatic acid to 1 of water, and leave from five to twenty minutes.
To pickle particles of German silver, first dip them in a compound of 12 parts of water and 1 part of nitric acid. The next step is to quickly immerse them in a compound of equal parts of sulphuric acid and nitric acid, and then rinse them in water, finally drying them in pine sawdust. This is a delicate operation, and very great care should be taken to see that the acid is not too strong or that the articles do not stay in the bath too long, as in either case great loss and damage would ensue by the dissolution of the metal. To stop the articles from rusting, wash them repeatedly with clean water and dry carefully.
To pickle zinc, scour it with sand and powdered pumice and apply a solution of potassium-ammonium tartrate thickened with sufficient clay to form a fluid paste. After allowing a few hours to elapse rub the articles with a brush dipped from time to tine into fine sand wet with the pickle.
93 6-10 parts Copper, 6 4-10 parts Zinc.
To plate with platinum, the clean metallic surface is planished and rubbed with a solution of 1 part platinum chloride, dissolved in 15 parts alcohol, and 50 parts ether, and when dry polished in a warm place with a dry cotton or woolen cloth. Bad places in platinum plating may be made good in a similar manner. The coating resembles steel in appearance, and imparts to bronze, brass or copper utensils a fine platinum surface.
To make plumber's soil, boil glue slowly in water until it is all dissolved. This, of course, will give you a thin solution of glue. Then stir in enough lamp-black to make the mass the consistency of paste, simmering the paste over a slow fire for the space of half an hour. Pursue the following method in testing your compound: Apply it with a brush to a piece of lead and allow it to get cool; then bend the lead backward and forward in the hand in order to judge of its adhesiveness. If it cracks while the lead is undergoing the process, there is too much glue in the compound, and it is n. g. If, on the other hand, it does not crack and adheres to the lead, it is all right.
For polish for pressed articles of brass, use an agent consisting of equal volumes of ox-gall and water boiled together. Keep the fluid, when cold, in a well-corked bottle, and, when using same, pour it into a glass or porcelain vessel.
Polish antimony with burnt magnesia upon soft leather or with fine jewelers' rouge.
Polishing balls for silver are given their form by means of an agglutinant. It is made by thoroughly stirring together 5 parts of whiting and 2 parts of yellow tripoli and working the mixture together with a solution of 1 part gum-arabic in 12 parts of water, until it becomes a stiff paste, and this is formed into balls (with the hands) about as big as the egg of an ordinary pigeon. These balls should be dried in moderately warm room, and after their perfect calidification should be packed in tin foil.