Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
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Electro-Metallurgy (Galvanoplasty or Electrotype)
Galvanoplasty or Electrotype, is the art of cold casting of metals by the agency of electricity.
Its applications are extensive. It is used to multiply engravings and photographs; to cover the faces of types with harder metal; to deposit gold, silver, and alloys on other metals, etc. The process types with harder metal to deposit gold, silver, pends upon the fact that an electrical current passed through a metallic solution properly prepared, will cause a decomposition of the solution ; the metal being deposited upon any conducting body attached to the negative pole (cathode) of a ) of a voltaic cell or battery. This is the pole attached to the zinc plate in all cases.
The Battery.
The term battery is properly applied to several voltaic cells united. Frequently, however, it is used to designate a single cell. The forms usually employed in practice are Smee's, Daniell's, and the nitric acid battery. In order to avoid conto avoid confusion, the following points must be well underwell understood. In all the batteries named, there are two plates and av exciting fluid. One of these plates is of zinc, which must be amalgamated by dipping it into weak sulphuric acid and rubbing the surface with mercury; or better still, immersing the whole plate in a bath of mercury. This must be repeated from time to time, when the battery is in use. This zinc plate is alone acted on by the exciting fluid. It is called the positive plate. Attached to it is a binding screw, by which a wire may be connected with the plate. This screw, or the end of the attached wire, is called the pole or electrode.
The name of the pole is opposite to that of the plate. The positive pole or anode being attached to the negative plate, and the negative pole or cathode to the positive (zinc ) plate.
The Decomposing Cell.
Usually the liquid to be decomposed (electrolyte) is kept in a separate vessel, and the current conveyed to it by wires. To the anode is usually The stones of more diluted color, such as the attached a piece of metal of the same character