Here's an update on this bottle. It was sent to me by my friend and your's Michael Polak. His price listing in his books are a bit suspect but this is his opinion on the bottle;
Rich,
Sorry that I haven't answered you sooner but I've been in the middle of updating the bottle book to the 5th Edition and then a bunch of business travel-now I'm playing e-mail catch-up. This bottle is really interesting. I've seen these types of bottles before in Europe, specifically Spain, and your guesss was a good one. They were used by the church for holy water but also by the military as a first-aid water/medicine bottle. If you take a look at the chain, you'll notice that the design is a heavy Spanish style. I'm not sure why the bottle had the chain except to keep it from being taken since it was the property of the church or the government. I would guess the time frame would be even late 1700's to early 1800's. Value is tough but since it appears to be in good condition, I would estimate $1-2K.
Good Bottle Hunting,
Mike.