'Simmering Granules' are a natural salt based product with added fragrance for use in burners/diffusers.  Simmering Granules are safe, clean and simple to use.  No water is required in the well of the burner, just a couple of teaspoons of Simmering Granules, which will gradually release their scent over several hours.  When the fragrance has evaporated, the Simmering Granules residue can be easily disposed of.