It is one thing to have a bottle that is amethyst from decades of sunlight, but what it basically does is ruin any value. As far as nuking that is more less used for ripping people off by convincing them of the extraordinarily rare color. You can turn your commons into amethyst, but you should...
It was probably filled in long ago for safety and sanitation reasons. It is worth digging down a few feet if not the whole way down. If the owner and you are sure it was the privy, then it is certainly worth digging. Best of luck and please let us know with pictures ect.
Value depends on the collector. Names of States, Cities, and Towns can sell very easily. If I had to put a value on the bitters bottle without knowing if it is actually a rare one, I would say $30 ish. Does it have any other writing on it?
You might be on top of a gold mine. Those two bottles are beautiful and highly collectible. When it gets warmer you should really dig and poke around thoroughly. I will put it this way. Some people dig for years before they find a bitters bottle like that.
Ahh good piece of info thank you. I actually thought at first it might of been a repro because of how modern the lettering pattern is. Very futuristic looking med.