A manual on dental metallurgy / by Ernest A. Smith.

  • Smith, Ernest A. (Ernest Alfred)
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: A manual on dental metallurgy / by Ernest A. Smith. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    vinegar, with access of air, it becomes gradually coated with a layer of green verdigris. It is superficially oxidised when heated in air, and at a bright red heat the alloy fuses, a proportion of the zinc burning away. The alloy is readily soluble in nitric acid. Impression trays, matrices, and a number of other dental appliances are made of German silver. c \(t Nickel Plating.—This is the process by which articles of iron, copper, and other metals are coated with metallic nickel by means of an electric current in a manner similar to gold and silver plating. The solution usually employed is the double sulphate of nickel and ammonia. It is of great importance that the articles to be coated should be absolutely clean and that any existing film of nickel should be entirely removed, the cleaning of the article being even more important in nickeling than in silvering or gilding. Small articles are frequently cleaned by rubbing with fine emery cloth, but a chemical method is more often employed, which consists in dipping the articles for a brief period into an acid bath. On account of its ^tre-mo hardnrnn the nickel deposit cannot bft T-mmishpf] j[jjse deposits of ffold and silver: it is essential, therefore, that thft articles be well polished before immersion in the plating solution. After polishing every trace of grease is removed by dipping in a solution of potash; then, after a thorough rinsing in water, the article is transferred to the plating bath and connected with the negative pole of a suitable battery, a plate of pure nickel being connected with the positive pole. Generally speaking, from half an hour to four hours will suffice for the deposition. Q
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