electroplating

[Eng. electro, and plat ing. A means of covering a metal or a metallic surface by exposure in a bath of a solution of a metallic salt, which is decomposed by electrolytic action. In 1800 Mr. Cruickshank, and in 1801 Wollaston, both English, made discoveries which led the way to electroplating. It was not, however, till 1838 that Mr. Spencer gave it a practical bearing by making casts of coin and casts in intaglio from the matrices thus formed. Profe or Jacobi, of Dorpat, in Ru ia, an independent inventor, in the same year also produced much-admired electroplated articles. The proce , briefly described, is as follows: The voltaic current employed is supplied by a constant battery, such as Daniell's or Bunsen's. In the simple form, the galvanic current is produced in the same ve el in which the metallic deposit is effected. The outer ve el of gla , stoneware, or wood, contains a solution of the metallic salt-say sulphate of copper. A smaller ve el of unglazed porcelain contains diluted sulphuric acid. A plate of zinc, forming the positive pole, is suspended in the acid solution, and connected with two copper medals by means of a copper wire. Electrolysis ensues, the copper in the solution is deposited on the medal which forms the negativo pole, and the strength of the solution is maintained by suspending a bag of crystals of sulphate of copper in the bath. In the