Core and chop the apples and put them in a saucepan with 4 cups of water. Bring to a boil over high heat, then reduce heat, cover, and simmer for 15 minutes stirring occasionally.
Remove from heat and mash the apples. Transfer mashed apples to a dampened jelly bag or flour sack towel. Hang up and let it drip into bowls for at least 2 hours or until it stops dripping.
Prepare the calcium water by mixing 1/2 cup of water with 1/2 teaspoon of Pomona's calcium powder. Set aside for later and refrigerate leftover calcium water for future use.
Sterilize the mason jars by boiling them in the water canner for 10 minutes. Then take off the heat.
In a separate bowl, mix 1 cup of sugar with 4 teaspoons of Pomona's pectin.
After 2 hours of dripping, mix 4 cups of apple juice, 1/4 cup lemon juice, and 4 teaspoons of calcium water in a medium saucepan.
Bring juice to a boil over high heat and then very slowly whisk in the sugar and pectin mixture. Stir constantly and vigorously for 1 to 2 minutes until all the pectin and sugar is dissolved. Once the jelly returns to a full boil, remove it from the heat.
Remove your jars from the canner and ladle hot jelly into the hot jars leaving 1/4 inch of headspace at the top. Add the lids and screw the bands on until fingertip tight.
Lower the filled jars carefully into the canner. Add the cover and bring the water to a rolling boil and process for 10 minutes (adjusting for altitude). Turn off the heat, remove the cover, and sit for an additional 5 minutes.
Remove the jars carefully and let them cool for 12 to 24 hours. Then check that the lids have sealed, label the jars, and store.