Rinse berries under cold running water and tear stalks off. Then mill berries or mash them. Add 1,5 l of cold water, add citric acid, piece of cinnamon and cloves, stir occasionally and let stand for 24 minutes.
Strain juice, weighten, add the same amount of sugar. Add benzoic acid and stir until sugar melts.
Fill sirup in clean bottles. Finally add 1 teaspoon of rum in each bottle. Close well and store in cold and dark.