Blackberries. Sugar.

The uncultivated berry is the best for making jelly and should be rather underripe. Put the berries into a stone jar, stand in a pan of cold water, cover the top of the jar and boil slowly until the berries are quite soft. Now strain the juice, and to each pint allow one pound of sugar. Pour the juice into a porcelain-lined pan and boil for twenty minutes.

Heat the sugar, add it to the boiling juice, and stir until the sugar is thoroughly dissolved, then allow to boil again, pour into hot jelly glasses and seal.

Another Method: Instead of cooking the berries, put them through a food chopper, strain the juice and throw away the seeds, then boil the juice.