Peel the cherries, wash and drain them. Select the raspberries, wash and also drain. Mash the cherries lightly and put them into the fruit basket of the steam juicer.
Add the raspberries. Fill the water pot with water, bring to the boil and place the juice pot with the fruit on top. Bring to the boil and juice for about 45 minutes over medium heat. Drain the juice once in a while.
Let the juice cool down. Remove 3/4 litre of juice, add jam sugar and lemon juice and bring to the boil while stirring. Cook for 4 minutes until bubbly. Gelling test: Put some jelly on a flat plate.
It must not melt any more. Otherwise, add some preserving sugar. Then add cognac and skim the jelly. Pour it hot into prepared glasses and close them well.