Pick over, wash, and drain currants. Put into a preserving kettle, adding a few at a time, and mash. Cook one hour, strain through double thickness of cheese-cloth. Return to kettle, add sugar, heat to boiling-point, and cook slowly twenty minutes. Add one quart raspberries when syrup again reaches boiling-point, skim out raspberries, put in jar, and repeat until raspberries are used. Fill jars to overflowing with syrup, and screw on tops.