Every thing that may abide the fire, ye shall make it go through the fire, and it shall be clean: nevertheless it shall be purified with the water of separation: and all that abideth not the fire ye shall make go through the water.
Anything that can survive being burned should be passed through fire; it will be clean. However, it must also be purified using separate water. Anything that doesn't survive the fire must be passed through this water.