Links to related information on other sites:

The Care of Silver 
http://www.bishopmuseum.org/research/pdfs/cnsv-silver.pdf

The Care and Preservation of Historical Silver 
http://www.thehenryford.org/explore/artifacts/silver.asp

2.11 Evaluation of Abrasive Materials for the Cleaning of Silver Objects 
http://www.getty.edu/conservation/science/abstracts/2.11.html