the ingredients in a large stock pot (or divide the ingredients over multiple pots if more glace is being prepared). Place
the pot(s) over high heat and bring to a boil. When the liquid begins to boil, gradually reduce the heat to produce a very low boil. As all
the contents come up to heat, the level of the heat under the pot can be set fairly low to maintain the low boil. When the water initially comes to a boil, a gray scum will rise to the top. This should be skimmed from the surface with a small ladle or spoon. As the cooking
proceeds, the scum will be replaced by yellow fat. This should also be carefully skimmed from the surface. Once the low boil is established at low heat, I check the pot and skim the surface only about once an hour.