Mulberry Jelly

From 1922:

Carefully examine the fruit, and reject any that are mouldy or unsound. Put the berries on the fire in a clean preserving pan with just a little water at the bottom to keep from burning. Boil for about 45 minutes, or until all juice is extracted from the berries. Pour through a colander, and then through a clean towel. Let it drip through the last of its own accord. Do not press or squeeze it, or your jelly will be cloudy. Next day measure the juice to put it on to boil. To every pint of liquid allow 1 lb. of sugar. Add the sugar when the liquid boils, and stir until it melts. Then cease stirring, and bring quickly to a boil. Boil fast for about an hour or until a little tried on a plate will jelly.