Dissolve five cents' worth of sulphate of copper in just as little water as possible. Solder smoothly, polish very bright with a cloth, and with a stick wet the solder with the solution and it will turn copper-color. It can be improved by polishing with bronze powder.
(2) To color tin solder yellow, it is best first to prepare a saturated solution of copper vitrol in water, dip an emery stick into it and touch the soldered part with it. Then take a piece of wire and touch the part again with this, by which a coppering takes place. To turn this yellow, take one part of a saturated solution of vitriol of zinc in water mixed with two parts of a copper vitriol solution, brush the coppered spot and touch with a zinc rod. A brass precipitate will result. The color may be still further improved by burnishing with gold powder and polishing with polisher.
When copper is soldered and the solder is to be colored like the surrounding copper, this can be done by moistening the solder with a saturated solution of vitriol of copper, and then touching the solder with an iron or steel wire. A thin skin of copper is precipitated, which can be thickened by repeating the process several times.
A valuable compound for hardening steel consists of:
1-3 Ammonium Chloride, 1-3 Borax, also a trace of Silicic Acid.
Clean the article thoroughly by a treatment in a bath of muriatic acid, 1 part; water, 4 parts, to remove all scale. Wash in hot water and tumble in sawdust wet with a solution of sulphate of copper in water, to which add as much sulphuric acid as is equal to the weight of the dry sulphate of copper. Use about two ounces of each to a gallon of water. You may also copper work that cannot be easily tumbled by dipping in the above solution hot. The work must be clean and free from grease.
To form copper nitrate dissolve the copper in nitric acid, concentrating the solution in a copper kettle.
A copper powder is prepared by putting a strip of sheet-zinc in a saturated solution of blue vitriol compounded with the same volume of hydro-chloric acid. The precipitation of the copper is as a fine powder, which, after the supernatant is decanted, is washed first with a weak solution of alcohol and then with a stronger one, quickly, to prevent oxidation.
Copper resinate is produced as follows: Dissolve 8.55 kilogrammes of ammonia soda (18 per cent.) in 90 liters of water, and heat the whole to a boil. Now throw in gradually and in small quantities 45 kilogrammes of good resin, stir diligently, and allow to boil until the resin has completely dissolved and has transformed into resin soap. Next dissolve 23.4 kilogrammes of copper sulphate (blue vitriol) in 18 liters of boiling water, and pour the resin soap into it. The cupric resinate now separates as a thick mass, which floats on the liquid. Gather, press out in a cloth, and dry, whereupon the resinate will be ready for use.