Place the soup bones, onion, celery, carrots, garlic, salt and water into a large crockpot. Turn on the low setting and simmer for 24 hours.
After the 24 hour slow simmer, turn off the crock pot and ladle the broth through a fine mesh strainer and a layer of cheesecloth into a stockpot.
Allow to cool and refrigerate for at least 6 hours.
Once the fat has risen to the top of the stockpot, remove it and proceed with the canning process.
Reheat the broth over medium heat.
Prepare the pressure canner by filling the canner with 2 inches of water. Bring to a boil.
Wash the jars, lids, and rings in hot soapy water.
Fill each clean jar with broth (use a food funnel for easy filling), leaving 1/2 inch headspace.
Wipe the jars with a clean, dry paper towel. Place the lids on the jars and tighten the rings.
Place the jars into the canner, close the lid, and allow the canner to steam for 10 minutes.
Place the regulator on and allow the pressure to rise to 10 pounds. Once it has reached 10 pounds, set a timer for 20 minutes. Watch the pressure gauge, if it drops, increase the heat, if it gets too high, lower the heat.
After 20 minutes, turn off the heat and allow the canner to drop in pressure naturally.
Once the pressure is down to zero, remove the lid and remove the jars with a jar lifter onto a towel lined cutting board. Allow the jars to rest on the cutting board for 12 hours before labeling and dating. Store in a cool, dry place. If any jars do not seal, refrigerate and use first.