Camphor and Silver Tarnish

Name: Susan
Status: other
Grade: other
Location: NY

Question: Many years ago, when I worked at the New-York Historical
Society, the displays of large silver trophies, tea sets etc. were
set up in almost air tight cases and camphor cakes were tucked into
the cases in September. The silver was still bright in June when the
museum closed for the summer. Why does camphor work this way?
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Susan,

The case were air tight.  So the only oxygen that could react with the 
silver was locked/sealed in in September.  The seals prevented any additional 
oxygen from entering the cases.  Apparently the camphor reacts with the 
oxygen faster than the oxygen reacts with silver.  Once the oxygen combined 
with the camphor, it couldn't react with the silver.  What gases were left 
in the cases?  Mostly nitrogen, a little argon and even less carbon dioxide. 

Warren Young
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