Just looking at the information you provided, the double headed eagle, the letter D year letter and the maker's mark TB. Educated guess. I believe the silver salt could be Dutch. Double headed eagle town mark of Middelburg used 18th century. Maker's mark T.B
for: Toussaint Brunel, registered in Middelburg 1758- 1791. The year letter D for Middelburg 1767.
Again proper images are required also for confirmation. For information how to attach embedded images:viewtopic.php?f=5&t=42199&p=118986#p118986