Put the water and rose leaves into a pan, cover and boil until the rose leaves go almost a white color. Then add the sugar and boil with the lid off until the syrup thickens. Dissolve the lemon salt cubes in 1/8 glass water (or add the lemon juice to the water), pour this into the pan after the syrup has thickened, bring to the boil once, remove from heat, and with a perforated spoon remove the foam on the syrup. Pour the jam into a bowl, and after it has completely cooled down, put into a jaar and close the lid tightly. Eat as desired.