Wow! That's just an incredible find. What does the seal say? I think you're right...snuff, but are you sure it is English...may be Continental (Dutch or similar)? I'd guess 1800-1840 or so?
I pick this bottle up at our bottle show about 20 years ago from a friend. It does have a chip in the lip but you don't come a cross a bottle like this. The name on the seal is F. D. BRETT.
This bottle was dug up at one of the first trading post in the port of Honolulu by Paul Kaneshiro. I also dug at this spot and was member of the bottle club and Paul is still actively involve with the club. A lot of black glass was dug at this spot and I was into black glass and gin bottles at the time. At the end of our Bottle Shows I ask Paul if he had any black glass he pulled this bottle still covered in dirt from the dig the night before. He said it had a chip on the lip and said he tried finding the chip after finding the bottle.