Transformation (Istihala)

196. If a Najis thing undergoes such a change, that it assumes the category of a Pak thing it becomes Pak, this process is called Istihala; for example, if a Najis wood burns and is reduced to ashes, or a dog falls in a salt-marsh and transforms into salt, it becomes Pak. But a thing does not become Pak if its essence or category does not change; like, if wheat is ground into flour, or is used for baking bread, it does not become Pak.