Placed in the oil burner reservoir and require no water. Can also be used to generally fragrance any room. They are normally used in oil burners, but are less messy as they don't need oil or water. Just put a spoonful of granules in the burner and replace them when they're used up.
Chase away cigarette odour by placing a few granules in ashtrays; freshen bathrooms and closets with a little bowl of granules, use them like potpourri.