You may have noticed that many of the recipes on this site involve cognac. From time to time, I (Doctor Cognac) find myself faced with inquiries from readers who wonder what to do if they lack the spirit. I'm ashamed to say that I've always been unable to provide a good answer to this question--until today. Just follow along below (I recommend going the route of the ether, not the prunes).
To sixty gals. of pure proof spirits add one pound of sweet spirit of nitre, one pound of cassia-buds, ground, one pound of bitter almond meal (the cassia and almond meal to be mixed together before they are put to the spirits), two oz. of orris root, sliced, and about thirty or forty prune-stones; a little butyric ether or spirit of prunes may also be added; stir them all well together two or three times a day, for three days or more; let them settle, then add one gal. of the best white wine vinegar, and if you wish to have it better than domestic brandy is in general, add to every four gals. one gal. of foreign brandy, and you will obtain a mixture nearly equal to the foreign produce.
From the same publication, you will find plenty of tips on how to dilute foreign spirits with domestics as well. Just keep my name out of it, I have enough business in front of the French courts as it is.