I found out today that there used to be a liqueur/cordial called Ros Solis, containing extracts from Drosera rotundifolia. I did a little research and found the following passage in From The House And Farm Accounts Of The Shuttleworths of Gawthorpe Hall, In the County of Lancaster at Smithils and Gawthorpe, From September 1582 to October 1621 (pp 939-940):
Rosa Solis or Rossolis. This name belongs both to a plant and to a liqueur or distilled water. Of the plant two kinds are described, the ros solis major and minor; in English the great and little sun-dew, also youth-wort and in the north of England red-rot, because it rotteth sheep, and in Yorkshire, moor-grass. It is sometimes named salsi rosa, of the dew which hangeth upon it when the sun is at the hottest. The distilled water herof that is drawn forth with a glass still, is of a glittering yellow colour like gold, and coloureth silver put therein like gold. It is a searing and caustic herb, and very much biting. It strengtheneth and nourisheth the body, especially if it be distilled with wine, and that liquor made therof which the common people do call rosa solis. If any be desirous to have the said drink effectual for the purpose aforesaid, let them lay the leaves of rosa solis in the spirit of wine, adding thereto cinnamon, cloves, maces, ginger, nutmegs, sugar, and a few grains of musk; suffering it so to stand in a glass close stopped from the air, and set in the sun by the space of ten days more: then strain the same and keep it for use. (Ger.) Leigh states that ros solis is very common in our Lancashire mosses, and carries a pellucid mucilage, in which, he presumes, consists its virtues in atrophies. Mark. gives a recipe “To make a cordial rosa solis.” Rossolis was a liqueuor so called from the plant ros solis, or rosée du soleil (sun-dew). It was so great a favourite with Louis XIV. that a particular sort was called Rossolis du Roi. (Planché) In C. C. Dic. the ingredients were 8 handfuls of the herb, in a gallon of brandy, 3 lb sifted fine sugar, 3 pints of milk-water, 1 oz. powdered cinnamon, 1 oz. white sugar-candy, 4 grains musk;p all strained through a cloth. In Dolby’s Cooks’ Dic. rossolis seems to have merely retained the name and not the substance or essense. It consists of pickled ornage flowers, musk, roses, cinnamon, and cloves, with fine sugar, and distilled spirit of jessamine; then colored crimson with cochineal. In the Accounts, in August 1612, aqua vitæ [it is doubtful whether this was brandy, or a cordial fermented water, made of beer strongly hopped] and rosa solis cost 17d.; November, to my mistress for rosa solis and aqua vitæ at several times, 10s.; also a bottle of rosa solis, 6s. 2d.; December, three quarts of aqua vitæ for my mistress, 5s.; rosa solis 3s.; January 1613, rosa solis for my mistress, 16d.; and delivered to my mistress to buy rosa solis and aqua vitæ, 10s.; and in May 1617, a quart of rosa solis to my mistress, 3s.