Re: salt vinegar reaction on silver

Try this first on some silver article of lesser value than the 
Morgan,such as a silver spoon, etc.

1. In a glass or stainless steel container make a hot solution of sodium 
carbonate [washing soda]about 5 %- it doesnt need to be boiling, just 
hot. In this place the silver article and piece of aluminum metal, a 
piece of a sheet or a nail. The aluminum and the aluminum MUST be in 
close physical contact.  After a few minutes remove the silver, rinse, 
and examine.

2. Query a silversmith or dealer in fine silverware, or a coin dealer 
[not the one you want to sell the coin to]. 

3. Try a commercial silver cleaner or tarnish remover [with no 
abrasive],  such as TARNEX.

Regards from C. A. Crutchfield