Place the bones in the Crock-Pot. Add the celery, carrots, onion, and garlic.
Fill the Crockpot with water. Cook on high for 2 hours. Then reduce heat and cook on low for 10 – 12 hours.
Strain the liquid. Save any bits of meat to use later in soup, but discard the bones and veggies.
Cool the broth in the refrigerator.
Remove any fat that collects on the top. Then line a colander with cheesecloth or a flour sack towel and strain the broth one more time.
Ladle the broth into jars and use a pressure canner to can the broth.
If you do not want to can your broth or do not have a pressure canner, you can freeze it in 1 and 2 cups portions. Just be sure to leave 1 inch of room in the container because the broth will expand when frozen.
Notes
You can use leftover bones from roasts and prime rib in this recipe. If your bones have not been previously cooked, you need to roast them at 350 degrees for 1 hour.