I asked the same question about seals and bottles to the Scotch Whisky Heritage Centre in Edinburgh and they said it wasn't bottled. In the 18th Century, it was casked and dispensed from liscenced premises into any suitable container available. Bottling was not done until the 19th Century.
There are basically three types of stone inclusion that you are likely to find in glass artifacts.
1. Refractory: i.e. fireclay or sillimanite etc. eroded from the pot or tank by the molten glass. These can be white or off white, or greenish brown especially if iron is present in any quantity...
Does anybody know how Scotch Whisky bottles were sealed in the late 18th Century?
I assume that a straight cork would be used, but was anything else added, e.g. wax.
and were the corks ever tied or wired down to the neck-ring? Any information would be appreciated.