Hi Norman,
If Mr Domenech dates it as 1800ish, then that is the date we should go with. One thing is certain, you got your money's worth and I am envious!
You may care to read the history of Alpacca/Nickel Silver in this Wikipedia article:
http://en.wikipedia.org/wiki/Nickel_silver#History
Plase keep us posted re whatever else you find out about this most interesting piece.
Cheers
Chris