From The Virginia Housewife Or, Methodical Cook by Mary Randolph:
“Raspberry Vinegar. Put a quart of ripe red raspberries in a bowl; pour on them a quart of strong well-flavored vinegar and let them stand 24 hours, strain through a bag, put this liquid on another quart of raspberries, which strain in the same manner, and then on a third quart; when this last is prepared, make it sweet with pounded loaf (granulated) sugar; refine and bottle it. It is a delicious beverage mixed with iced water.”