Soak the gelatine in cold water. Remove the gelatine from the water and squeeze out the excess moisture. Place the gelatine in a large saucepan with the sugar,citric acid and water. Stir over a gentle hear until the sugar has dissolved. Stop stirring and bring the mixture to the boil. Boil steadily for 20 minutes. Add the rosewater and leave the mixture to stand for 15 minutes. Pour half of the mixture into an oiled 18cm square tin. Put in a cold place to set.