"This sap is just a raw ingredient, it is useless as it is to an alchemist. So what we want to do is make it safe for consumption or direct use on wounds. As you know it can be used to make a paste that soothes pain, but that is useless to open wounds or internal pain." The old man held one of the vials of oozing vine sap and poured it in to the empty cauldron. "The heat we will use will need to be low. We want to cause the different things that make the sap up to separate and not cook." He slowly heated the cauldron and added a small amount of water. The rules with the extraction skill is simple, it's not a magic that instantly separates something. You need to have the things you wish to separate under the correct conditions. This can only be found by experimenting. The best alchemists could take the poison out of any liquid or herbs." The old man watched the heat intently.