After extensive testing, I found that chicken bones are the worst for making any type of broth or gelatin. They don't gel up and generally there's less nutrition in them.

My best advice would be to go to your butcher, ask for NECK bones or FEET (actual pigs feet or beef feet bones.) Most butchers throw this stuff away and you will be able to get it for pennies on the dollar or even for free. Every few weeks, I go to my butcher and ask him for bones and he gives me a huge bag of them. I have an entire shelf in my freezer devoted to bones. I have lamb neck bones, lamb knee bones, pigs feet, and beef neck bones.) Every time I use these to make my broth, my bone broth gels up and I make quality gelatin. Ideally, you want bones with a bit of meat on them and bones with visible cartilage and marrow.

If you want to make a good bone broth or gelatin:

1. Place the bones in a pie tin or cooking tray and place it in the oven and roast at 200 degrees for 30 minutes.
2. Get enough bones to fill the entire bottom of a crockpot with. You should not be able to see the bottom of the pot.
3. Smash some of the softer bones with a hammer. Alternatively, you can ask your butcher to cut them open for you so the marrow is exposed.
4. Place all of the bones in the crockpot.
5. Fill up the crockpot almost entirely with water. Leave about an inch from the top so it doesn't boil over.
6. Add 1 tablespoon ACV or balsamic vinegar for every 2 cups of water.
7. Add generous amounts of Himalayan crystal salt or celtic sea salt.
8. Add a few tablespoons of garlic powder or one clove of garlic.
9. Add fresh or dried anise.
10. Add a "twig" of rosemary. Dried rosemary works too.
11. Add a generous amount of black peppercorns. If you want an antioxidant boost, add a small amount of turmeric. The turmeric and pepper work in a synergistic manner.
12. Bring to a slow boil and keep it like that for a few minutes.
13. After a few minutes, you should see an off-white foam rising to the top. Get a ladle and skim the scum out quickly.
14. Reduce heat as much as possible and keep it simmering gently for at least 4 hours. Do NOT keep the broth boiling. You can even do it overnight. I have a gas stove and my house never blew up when making bone broth for extended periods of time.

I do bone broth once a week because I like to make a chicken soup from it that becomes a quick and easy meal for me during the week.

After cooking a small chicken, I'll pick off all the skin and meat that I can, but I don't spend a lot of time on it, so there may be some meat left. I put the carcass in a pot and cover with enough filtered water to cover. I add a splash of apple cider vinegar, as well as some peppercorns and sea salt. The vinegar will you get the most from the bones and marrow. I bring it to a boil and once there, let it boil only for about 5 minutes. I then turn it down to simmer for 12-24 hours depending on how much I have cooking. You can even do this in the crock pot. Check out this link for perpetual bone broth: http://nourishedkitchen.com/perpetual-soup-the-easiest-bone-broth-youll-make/ This is something I will do sometime when I don't have small kids around.

Once the broth is made, I strain out the chunks and return the broth to the pot. Then I add cooked chicken, celery, onion, carrots, minced garlic, and salt and pepper. I cook this until the carrots are softened. Voila, chicken soup!

If you are talking about the amount of meat that is on a chicken foot (or backs/wings), don't worry about it. Anyway, meat adds some flavor to the broth -- so far as I know (but am waiting to be corrected) the reason people generally remove the meat first is to eat it. Once you make broth, the meat will be too tough to eat. If all I have is bare bones, I usually add a few wings or backs anyway.

My recipe:

Put bones & parts in crockpot with 1 or 2 carrots, 1 or 2 stalks celery, 1 onion cut into 8ths, 10-15 peppercorns. Cover w/ water, cook on low 10-12 hours, add bay leaf, cook a couple more hours. Strain, chill overnight and scrape off fat if desired.

Mollyboo is right that the vinegar will help to get all the minerals out of the bones, but I don't like the flavor so I skip it.

Editing: now I see that you said chicken legs, not chicken feet. The problem with legs is just that you will need lots of them to get enough bones. I'd tend to cook those any way you like to eat them, save the bones, and keep doing that until you have the equivalent of a pot full of bones. If you want a broth that gels nicely, add a few chicken feet, if you want more flavor, add backs/wings.

I made the bone broths and turned out great. I made half of it into chicken soup and I am saving the other half for another time. Does anyone know if I can freeze the broth, or how long it keeps in the fridge?