A stock cooked for so long that it moonlights as a broth. Gather the ingredients for Brown Beef Stock, White Veal Stock, Pork or Ham Stock, Poultry Stock, or Brown Poultry Stock. At least half the bones should be rich in collagen (such as chicken feet, turkey wings, pork neck bones, veal knuckles, and oxtails). Set the vegetables and herbs aside, and roast or blanch the bones as directed. Place the bones in a stockpot and add cold water to cover by 3 inches. Bring to a low simmer and skim any scum that rises to the top for the first hour. Partially cover and simmer gently until the bones begin to disintegrate when prodded with a spoon, at least 10 hours for poultry and veal and up to 16 hours for beef and pork bones. Check the water level every 2 hours and add boiling water as needed to keep the bones submerged (for beef bones, you may have to add up to 12 cups water). Add the vegetables and herbs for the last hour of cooking. Strain, cool, skim off any fat, and store as directed.