Wash the jars you are going to use. They need to be sterilized even if they are already clean. Running them through the dishwasher is a simple way to do this.
Fill your water bath canner about half full with water and set aside. Put a metal kitchen spoon in the freezer to check consistency of jam later.
Blanch your peaches in boiling water for 30-45 seconds per batch, and then plunge them into an ice water bath as each batch finishes. Slip the skins from the fruit.
Peel peaches. Chop into medium-small chunks. As you chop, stir in 1 cup of the sugar to keep peaches from browning.
Measure pectin into a small bowl and the remaining 9 cups of sugar into another. Place peaches, raspberries, lemon juice and butter in a large pot on high. Use an immersion blender to puree jam until it reaches the consistency you desire.
Turn water bath canner on high and bring to a boil.
Slowly add pectin to fruit stirring constantly. Bring the fruit mixture to a full boil, then add the sugar. Stir until it returns to a boil, then boil 1 minute continuing to stir constantly. The jam will look thin even though it is ready. If you want to know how thick it will set up after it's cool dip the frozen spoon into the jam for a moment and then run your finger down the spoon.
Us a wide funnel to fill pint or half pint jars. Leave 1/4" - 1/2" headspace.
Wipe the rim of the jar down with a clean, damp towel to make sure it is perfectly clean, then place a lid and ring on the jar.
Place your jars in the water bath canner. Make sure there is enough hot water to cover the jars by 2". Bring the canner back up to a full boil and boil for the recommended processing time.
Pints and half-pints of need to be processed a minimum of 10 minutes in a water bath canner. If you live above 1,000 feet you need to add more time to adjust for altitude. For 1,001 - 3,000 feet add 5 minutes. For 3,001 - 6,000 feet add 10 minutes. For 6,001 - 8,000 feet add 15 minutes. For 8,001 - 10,000 feet add 20 minutes.
Remove your jars to clean towels after processing and allow the lids to pop down - no poking!
When the lids have sealed your jam is ready to store.