Grape jelly

Ingredients: 
1. 1 1/2 kg green grapes
2. 2 tsp fruit pectin crystals     
3. 5 c granulated sugar
4. 1 litre water
       
Method: 
1. Boil crushed grapes with water on low heat for 15 minutes. 
2. Put in muslin cloth. Let drip, until juice measures 4 cups.
3. In a pot, bring juice and pectin to boil. Stir in sugar; boil vigorously, stirring for 10 minutes.
4. Remove from heat. Let cool. 
5. Pour into canning jar.