Maintaining the proper ratio of bones to water is crucial for making an excellent-quality stock. For beef, veal, poultry, or game stocks, here’s the basic rule of thumb: To make 1 gallon of stock, use 8 pounds of bones, 6 quarts of water, 1 pound mirepoix and 1 standard bouquet garni. It is important to combine the bones with cool water and bring the water slowly to a boil, but then to reduce the heat to a simmer if the stock continues to boil. Any blood or impurities will cloud the stock. Constant skimming of the impurities will determine how clear the final stock is. After 1 hour, add the flavoring ingredients. Spices and herbs will generally release their flavor sufficiently after about 15 to 30 minutes. Other flavoring ingredients can be added to simmer as well (ginger, mushrooms, tomatoes, wines, etc.). Brown stocks generally take about 6 to 8 hours of simmering time. White and brown poultry stocks should be allowed a minimum of 3 hours, and vegetable or seafood stocks need about 1 hour. Many chefs will take a finished stock and use it as a flavorful poaching liquid or as a base in soups and stews. Beef and chicken stocks can be reduced by a little over a half — to a “demi-glace” — at which point they are thicker and have a more concentrated flavor. Demi-glaces are often used as a base for sauces. If a demi-glace is reduced again — roughly by half — it will thicken to a gelatinous consistency when cool. This is called a “glace” and can also be used as the foundation of a sauce or in other recipes where an intense, rich flavor is called for.