Skin the peaches by plunging them into boiling water. Remove the pit, cut the peaches into rather large quarters. Put 1/4 the sugar and 1 cup of water into the preserving pan. When boiling fiercely, put in the peaches, raspberries and lemon juice. Cook over a brisk heat for 15 minutes, skim. Meanwhile, combine the remaining sugar with the product chosen to thicken the jam, according to the instructions. Add to the jam, cook for a further 8 to 10 minutes, stirring constantly. Remove from the heat, wait for a few minutes before pouring into jars.
