Wash fruit, soak 8 hours in the 4 c of water. Place over heat in water in which it has been soaked; simmer until very soft; rub through coarse sieve, return pulp to heat; when it reaches boiling point, add sugar and simmer gently for 40 to 45 minutes, stirring almost constantly as it scorches very easily. Add cinnamon while cooking. Pour into sterilized half-pints to within 1 cm of top. Put on cap, screw band firmly tight. Process in boiling water bath ten minutes.