Epsoak Epsom Salt. Premium quality Epsom Salt (magnesium sulfate). Packaged in a 10 pound resealable bulk bag. Natural white color. Standard, medium grain. USAGE INSTRUCTIONS: For a relaxing soak - Add two cups of Epsom Salt to a warm bath (for a standard-sized bathtub). Soak for at least 12 minutes. Relieving tired feet - Soak tired, aching feet in warm water to which a handful of Epsom Salt has been added. Rinse with cool water. INGREDIENTS: Magnesium Sulfate.