Original Receipt in 'The Art of Cookery Made Easy and Refined' By John Mollard (Mollard 1802)TARRAGON VINEGAR.
Put into a stone jar half a pound of fresh gathered tarragon leaves and two quarts of best common vinegar, and let them ferment a fortnight; then run it through a flannel bag, and add to it a quarter of an ounce of isinglass dissolved in cyder. Put it into a clean jar, let it stand till fine, pour it off, put it into small bottles, cork them close, and set them in a dry place.