IIRC it is sulpherous, but I'm in no wise certain.
All I know is it's not the above mentioned substance.
Not sulphuric acid by any chance?
4,611 posted on 06/27/2006 12:56:29 PM PDT by Irish_Thatcherite
(A vote for Bertie Ahern is a vote for Gerry Adams!| IRA supporters on FR are trolls, end of story!)
I *could* always google "copper, brass, patina, chemical"
4,613 posted on 06/27/2006 1:03:59 PM PDT by King Prout
(many complain I am overly literal... this would not be a problem if fewer people were under-precise)