Antiques, their restoration and preservation / by A. Lucas.

  • Alfred Lucas
Date:
[1932]
Catalogue details

Licence: In copyright

Credit: Antiques, their restoration and preservation / by A. Lucas. Source: Wellcome Collection.

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    if the action is allowed to continue too long, or if the operation is often repeated with the same vessel, this will soon be destroyed. Instead, how¬ ever, of an aluminium vessel, a large piece of aluminium may be placed in contact with the silver object in a porcelain basin filled with sodium carbonate solution. This, though largely consisting of silver chloride, also contains compounds of copper originating in the copper alloyed with the silver. When the silver is of poor quality and contains a large pro¬ portion of copper the corrosion may be of a green colour and the object may look so like corroded copper or bronze that it will often be mistaken for these metals, and it is not until it has been cleaned that its true nature will become manifest.1 As already stated, two excellent solvents for silver chloride are ammonia and potassium cyanide respectively, which have been recommended for removing tarnish. But with any corrosion greater than tarnish, simple rubbing of the surface with a dilute solution of the solvent would be useless, and it becomes necessary to soak the object in the solution and to leave it for several hours at least and possibly for days. Under these conditions the use of potassium cyanide is not advisable, for not 1 Several such cases have occurred in the author’s experience. Slight Corrosion
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